1. The patient has been on mechanical ventilation for 14 days following surgery and is now being considered for weaning and extubation.
2. However, he remains sedated and is difficult to arouse, which will impair his respiratory drive and ability to protect his airway.
3. Additionally, he has edema in his lower limbs and abdomen which may interfere with ventilation and the ability to wean from the ventilator. Gradual reduction of sedation and careful monitoring will be needed.
APRV (Airway Pressure Release Ventilation) is a ventilation mode that applies continuous positive airway pressure (CPAP) for a prolonged high-pressure phase (T high) to recruit and maintain lung volume. It then has a brief low-pressure release phase (T low) where most ventilation and CO2 removal occurs. Compared to conventional ventilation, APRV may cause less ventilator-induced lung injury due to maintaining higher end-expiratory lung volumes without repetitive opening/closing of alveoli. It also allows for spontaneous breathing which improves patient comfort and outcomes. While APRV does not reduce mortality, it can improve other outcomes such as shorter ventilation times and ICU stays.
This document discusses respiratory failure and various modes of mechanical ventilation. It begins by distinguishing between respiratory failure and respiratory insufficiency. It then covers initiating mechanical ventilation using either volume ventilation or pressure ventilation. Various modes are discussed including volume-targeted modes like control, assist, SIMV+PS. Pressure-targeted modes like pressure control ventilation and PSV are also covered. The document discusses the challenges of ventilating ARDS patients and how newer dual modes and closed-loop modes can help minimize ventilator-induced lung injury while maintaining lung recruitment and pressures. It also introduces APRV and bi-level ventilation as newer modes to apply PEEP above the lower inflection point.
Mechanical ventilation provides positive pressure to move gas into the lungs. There are two main types: volume-controlled ventilation which preselects tidal volume and pressure-controlled ventilation which preselects pressure. Modes include controlled mandatory ventilation (CMV), assisted control ventilation (AC), and synchronized intermittent mandatory ventilation (SIMV). Positive end-expiratory pressure (PEEP) is used to prevent alveolar collapse. Weaning involves gradually reducing ventilator support by shifting modes and rates until the patient can breathe independently. Complications include barotrauma, infection, and weakness.
The document discusses the physiology of mechanical ventilation. It begins by describing the historical origins of mechanical ventilation in the 16th century. It then covers the basics of the respiratory system and how positive pressure ventilation works by forcing the lungs to expand during inspiration. The document discusses various pressures, volumes, compliances and resistances involved in spontaneous and mechanically assisted breathing. It covers indications for mechanical ventilation and the goals and potential effects of positive pressure ventilation. Monitoring of the patient on mechanical ventilation is also emphasized.
1. The document discusses various modes of mechanical ventilation including volume control, pressure control, SIMV, and PSV. It describes the settings, parameters, and considerations for each mode.
2. Initial ventilator settings should aim for adequate oxygenation and ventilation while minimizing work of breathing. Settings like tidal volume, respiratory rate, and PEEP are adjusted based on factors like patient size and condition.
3. Weaning from mechanical ventilation involves gradually reducing support through methods like spontaneous breathing trials, decreasing SIMV frequency, and lowering pressure support levels to assess the patient's ability to breathe independently. Readiness criteria and a stepwise protocol are
The document provides an overview of mechanical ventilation, including indications for intubation and ventilation, principles of mechanical ventilation, patterns of assisted ventilation, ventilator dependence and complications, liberation from mechanical ventilation through weaning, and troubleshooting arterial blood gases. Key topics covered include indications for intubation, objectives of mechanical ventilation, strategies for mechanical ventilation including use of airway pressures and compliance, patterns of assisted ventilation such as assist control ventilation and pressure control ventilation, complications of mechanical ventilation, parameters for bedside weaning, and low volume ventilation strategies for ARDS.
1) ARDS is a common and serious condition in the ICU characterized by diffuse lung inflammation and damage to the lungs' ability to oxygenate blood. It can develop due to direct or indirect injury to the lungs from a variety of causes like pneumonia, sepsis, trauma, etc.
2) Mechanical ventilation can further damage injured lungs if not performed carefully. A lung protective strategy using low tidal volumes has been shown to significantly reduce mortality in ARDS patients.
3) Treatment involves identifying and treating the underlying cause, conservative fluid management, nutritional support, and lung protective ventilation with low tidal volumes and adequate PEEP to prevent lung collapse without overdistension.
The document discusses two types of acute respiratory distress syndrome (ARDS) - pulmonary (direct) ARDS and extrapulmonary (indirect) ARDS. It notes key differences in characteristics and responses to mechanical ventilation strategies between the two types. Specifically, extrapulmonary ARDS patients tend to have better responses to higher levels of positive end-expiratory pressure (PEEP) compared to pulmonary ARDS patients. The document also reviews various mechanical ventilation strategies and studies regarding lung-protective ventilation in ARDS.
APRV (Airway Pressure Release Ventilation) is a ventilation mode that applies continuous positive airway pressure (CPAP) for a prolonged high-pressure phase (T high) to recruit and maintain lung volume. It then has a brief low-pressure release phase (T low) where most ventilation and CO2 removal occurs. Compared to conventional ventilation, APRV may cause less ventilator-induced lung injury due to maintaining higher end-expiratory lung volumes without repetitive opening/closing of alveoli. It also allows for spontaneous breathing which improves patient comfort and outcomes. While APRV does not reduce mortality, it can improve other outcomes such as shorter ventilation times and ICU stays.
This document discusses respiratory failure and various modes of mechanical ventilation. It begins by distinguishing between respiratory failure and respiratory insufficiency. It then covers initiating mechanical ventilation using either volume ventilation or pressure ventilation. Various modes are discussed including volume-targeted modes like control, assist, SIMV+PS. Pressure-targeted modes like pressure control ventilation and PSV are also covered. The document discusses the challenges of ventilating ARDS patients and how newer dual modes and closed-loop modes can help minimize ventilator-induced lung injury while maintaining lung recruitment and pressures. It also introduces APRV and bi-level ventilation as newer modes to apply PEEP above the lower inflection point.
Mechanical ventilation provides positive pressure to move gas into the lungs. There are two main types: volume-controlled ventilation which preselects tidal volume and pressure-controlled ventilation which preselects pressure. Modes include controlled mandatory ventilation (CMV), assisted control ventilation (AC), and synchronized intermittent mandatory ventilation (SIMV). Positive end-expiratory pressure (PEEP) is used to prevent alveolar collapse. Weaning involves gradually reducing ventilator support by shifting modes and rates until the patient can breathe independently. Complications include barotrauma, infection, and weakness.
The document discusses the physiology of mechanical ventilation. It begins by describing the historical origins of mechanical ventilation in the 16th century. It then covers the basics of the respiratory system and how positive pressure ventilation works by forcing the lungs to expand during inspiration. The document discusses various pressures, volumes, compliances and resistances involved in spontaneous and mechanically assisted breathing. It covers indications for mechanical ventilation and the goals and potential effects of positive pressure ventilation. Monitoring of the patient on mechanical ventilation is also emphasized.
1. The document discusses various modes of mechanical ventilation including volume control, pressure control, SIMV, and PSV. It describes the settings, parameters, and considerations for each mode.
2. Initial ventilator settings should aim for adequate oxygenation and ventilation while minimizing work of breathing. Settings like tidal volume, respiratory rate, and PEEP are adjusted based on factors like patient size and condition.
3. Weaning from mechanical ventilation involves gradually reducing support through methods like spontaneous breathing trials, decreasing SIMV frequency, and lowering pressure support levels to assess the patient's ability to breathe independently. Readiness criteria and a stepwise protocol are
The document provides an overview of mechanical ventilation, including indications for intubation and ventilation, principles of mechanical ventilation, patterns of assisted ventilation, ventilator dependence and complications, liberation from mechanical ventilation through weaning, and troubleshooting arterial blood gases. Key topics covered include indications for intubation, objectives of mechanical ventilation, strategies for mechanical ventilation including use of airway pressures and compliance, patterns of assisted ventilation such as assist control ventilation and pressure control ventilation, complications of mechanical ventilation, parameters for bedside weaning, and low volume ventilation strategies for ARDS.
1) ARDS is a common and serious condition in the ICU characterized by diffuse lung inflammation and damage to the lungs' ability to oxygenate blood. It can develop due to direct or indirect injury to the lungs from a variety of causes like pneumonia, sepsis, trauma, etc.
2) Mechanical ventilation can further damage injured lungs if not performed carefully. A lung protective strategy using low tidal volumes has been shown to significantly reduce mortality in ARDS patients.
3) Treatment involves identifying and treating the underlying cause, conservative fluid management, nutritional support, and lung protective ventilation with low tidal volumes and adequate PEEP to prevent lung collapse without overdistension.
The document discusses two types of acute respiratory distress syndrome (ARDS) - pulmonary (direct) ARDS and extrapulmonary (indirect) ARDS. It notes key differences in characteristics and responses to mechanical ventilation strategies between the two types. Specifically, extrapulmonary ARDS patients tend to have better responses to higher levels of positive end-expiratory pressure (PEEP) compared to pulmonary ARDS patients. The document also reviews various mechanical ventilation strategies and studies regarding lung-protective ventilation in ARDS.
capnography refers to the noninvasive measurement of the partial pressure of carbon dioxide (CO2) in exhaled breath expressed as the CO2 concentration over time. The relationship of CO2 concentration to time is graphically represented by the CO2 waveform, or capnogram . Changes in the shape of the capnogram are diagnostic of disease conditions, while changes in end-tidal CO2 (EtCO2), the maximum CO2 concentration at the end of each tidal breath, can be used to assess disease severity and response to treatment. Capnography is also the most reliable indicator that an endotracheal tube is placed in the trachea after intubation.
This document discusses mechanical ventilation waveforms. It begins by stating the objectives are to discuss commonly used waveforms, their applications, and combined waveforms. It then provides an outline and introduction on waveforms and how they represent ventilator data graphically over time or against each other. The majority of the document discusses specific commonly used waveforms including pressure-time, flow-time, and volume-time curves and how to interpret each to evaluate the patient and ventilator settings.
This document discusses anesthesia considerations for patients with respiratory diseases. Key points include:
- Patients with respiratory diseases like COPD are at higher risk for postoperative pulmonary complications. Careful preoperative evaluation and optimization is important.
- General risks include older age, smoking history, and type/duration of surgery. Regional anesthesia can help reduce risks when possible.
- Intraoperatively, strategies like lower tidal volumes, PEEP, and careful extubation can help. Postoperatively, techniques like incentive spirometry and ambulation aid lung expansion.
- Diseases discussed in detail include COPD, asthma, bronchitis, emphysema, and restrictive diseases. Management aims to address issues like hypo
1) The document discusses various physiologic variables that can predict a patient's readiness to be weaned from a mechanical ventilator, including the rapid shallow breathing index, maximal inspiratory pressure, and compliance.
2) It contrasts approaches to weaning patients such as a spontaneous breathing trial using T-piece trials or low levels of pressure support, and describes criteria for indicating a successful spontaneous breathing trial.
3) Common reasons for weaning failure include respiratory failure that has not improved, organ system dysfunction, low oxygenation or ventilation status, and lack of an intact airway protective mechanism.
Cardiac output can be measured through various invasive and non-invasive methods. The pulmonary artery catheter using thermodilution is still considered the gold standard but is invasive. Minimally invasive methods include lithium dilution, pulse contour analysis devices, esophageal Doppler, and transesophageal echocardiography. Non-invasive methods include partial gas rebreathing, thoracic bioimpedance, and Doppler ultrasound. The ideal monitor is accurate, continuous, non-invasive and provides reliable measurements during different physiological states.
This document discusses ventilation in obstructive airway diseases. It provides indications and contraindications for non-invasive ventilation (NIV) including criteria such as respiratory rate greater than 25 breaths per minute and moderate to severe respiratory acidosis. NIV can be used to support patients with acute exacerbations of COPD or asthma to reverse respiratory failure. Ventilator settings aim to support gas exchange, reduce work of breathing, and prevent complications. Dynamic hyperinflation can cause auto-PEEP which increases workload and impairs hemodynamics. Settings to treat auto-PEEP include increasing expiratory time, reducing tidal volume, and applying external PEEP.
This document provides an overview of difficult airway management in the ICU. It discusses factors that can lead to difficult intubation in ICU patients such as remote location, unstable physiology, and patient factors. It describes different techniques for managing the difficult airway including anticipated difficult airways, unanticipated difficult airways, and cannot intubate/cannot ventilate scenarios. Equipment for difficult airways is outlined including video laryngoscopes, fiberoptic scopes, supraglottic airway devices, and surgical airway options like needle cricothyroidotomy. Pre-oxygenation techniques and adjuncts to improve laryngoscopy views are also summarized.
Ultrasonography evaluation during the weaning processFadel Omar
Ultrasonography can be useful for assessing cardiac function, diaphragm mobility, pleural effusions, and lung aeration during the mechanical ventilation weaning process. Assessment of left ventricular diastolic function, diaphragm excursion and thickening fraction, size of pleural effusions, and lung ultrasound score can provide information on risks of weaning failure and identify issues like cardiogenic pulmonary edema. Removal of moderate or large pleural effusions may improve chances of successful weaning in patients with respiratory dysfunction. Lung ultrasound before and after spontaneous breathing trials can detect loss of lung aeration associated with post-extubation respiratory issues.
Recruitment Maneuvers in ARDS Dr Chennamchetty Vijay KumarVizae Kumar Chennam
This document discusses recruitment maneuvers for mechanically ventilated patients. It begins with a case study of a patient presenting with respiratory failure. It then provides definitions and the physiological rationale for recruitment maneuvers, including how alveolar collapse occurs in ARDS. Different types of recruitment maneuvers are described, as well as factors that influence their effectiveness. Clinical trials on recruitment maneuvers are summarized, which found no significant reduction in mortality but some improvement in secondary outcomes. Limitations of recruitment maneuvers are discussed, such as potential hemodynamic effects. The document concludes with emphasizing the complexity of lung recruitment and ongoing controversies regarding recruitment maneuvers.
This document discusses the physiology of positive pressure ventilation. It covers:
- The goals and types of mechanical ventilation including positive and negative pressure ventilation.
- Key concepts including pressure gradients, time constants, airway pressures, and the effects of PEEP.
- Modes of ventilation including volume-controlled, pressure-controlled, and how they differ in terms of triggers, limits, and cycling.
- Waveforms including pressure, volume, and flow and how they are used to assess ventilation.
The document provides an overview of the fundamental physics and physiology principles underlying mechanical ventilation.
1) ARDS is characterized by hypoxemia, bilateral lung infiltrates, and respiratory failure not fully explained by cardiac failure. The Berlin definition classifies ARDS as mild, moderate, or severe based on oxygenation levels.
2) Management of ARDS focuses on treating underlying causes, preventing complications, and using ventilator strategies like low tidal volume ventilation to prevent ventilator-induced lung injury.
3) Other ventilator strategies discussed include prone positioning, neuromuscular blockade, recruitment maneuvers, and extracorporeal membrane oxygenation for severe cases, though evidence on benefits is mixed.
This document provides an overview of non-invasive ventilation (NIV). It discusses the history of NIV, types of ventilators and modes used, interfaces, indications and contraindications. Guidelines are provided on how to start and monitor NIV, including adjusting settings based on patient response. Advantages, disadvantages and complications of NIV are reviewed. Applications of NIV for specific clinical conditions like COPD exacerbation and acute cardiogenic pulmonary edema are covered. The document aims to educate medical professionals on best practices for administering and monitoring patients receiving NIV treatment.
1. Separation from cardiopulmonary bypass (CPB) after cardiac surgery is a gradual transition from full mechanical support to spontaneous heart and lung function.
2. During weaning, transesophageal echocardiography provides information to guide decision making. Weaning involves preparing the patient, checking readiness, gradually reducing bypass support while monitoring cardiac function, and treating any failure to wean.
3. Causes of failure to wean include left ventricular failure from issues like graft failure, ischemia, or valve problems, right ventricular failure from causes such as pulmonary hypertension or ischemia, and inappropriate vasodilation from various potential issues.
Critically ill patients requiring noninvasive or invasive ventilation often present to emergency departments, and due to hospital crowding and constrained critical care services, may remain in the emergency department for a prolonged duration. Compared with their intensive care unit counterparts, emergency department clinicians may have variable exposure to management of this patient population and may lack knowledge and expertise, particularly in their
longitudinal management beyond initial stabilization. This
review has discussed several key aspects of management
of noninvasive and invasive ventilation, with a particular emphasis on initiation and ongoing monitoring priorities,
and focused on maintaining patient safety and improving
patient outcomes.
This document discusses ventilation strategies for a patient with acute respiratory distress syndrome (ARDS). It provides details of the patient's initial presentation and management, including mechanical ventilation settings. It describes the rationale for using low tidal volume ventilation to minimize ventilator-induced lung injury. The patient required aggressive management for sepsis and hypoxemia including recruitment maneuvers and increasing PEEP and mean airway pressures. Despite these efforts, the patient could not be weaned from high FiO2 and developed multi-organ failure and died. The document recommends using low tidal volumes, limiting end-inspiratory pressures, adequate PEEP, and considering recruitment maneuvers to optimize ventilation in ARDS.
Non-invasive ventilation (NIV) provides ventilatory support without intubation through a non-invasive interface like a mask. It is used initially to treat type 2 respiratory failure and prevent need for mechanical ventilation. Benefits include avoiding complications of intubation and improving outcomes by reducing mortality, morbidity, ICU/hospital stay, and costs. NIV is appropriate for patients with acute or acute on chronic respiratory failure who are cooperative, hemodynamically stable, and have an adequate cough reflex. Factors determining success include careful patient selection, skilled application and monitoring, and timely transition to invasive ventilation if needed.
The document discusses anesthesia considerations for thoracoscopy and VATS procedures. It covers preoperative assessment and optimization, intraoperative anesthetic management including lung isolation techniques, ventilation strategies, positioning, and management of issues like hypoxemia. Protective lung ventilation principles with low tidal volumes, PEEP, and recruitment maneuvers are emphasized for lung protection during one-lung ventilation.
Noninvasive ventilation (NIV) refers to ventilatory support without an invasive artificial airway such as an endotracheal or tracheostomy tube. NIV can be delivered via nasal or oronasal masks connected to positive pressure ventilators. The document traces the history of ventilation from ancient times to modern NIV techniques. It describes various interfaces, modes of ventilation including CPAP, contraindications, and suitable clinical conditions for NIV support such as COPD exacerbations and cardiac pulmonary edema.
The document discusses ventilation and different modes of noninvasive ventilation. It provides details on:
1) How ventilation works through pressure differences that cause air to flow into and out of the lungs. Different factors like resistance and Boyle's law impact this process.
2) The history and development of noninvasive ventilation, from early negative pressure devices to current use of positive pressure ventilation delivered noninvasively through masks.
3) Modes of noninvasive positive pressure ventilation including volume ventilation, pressure ventilation, bilevel PAP, and CPAP. The benefits and limitations of noninvasive ventilation are also summarized.
This document discusses respiratory failure and mechanical ventilation. It covers three key areas: causes of respiratory failure including neurological, muscular and airway issues; criteria for assessing readiness to wean from ventilation including adequate oxygenation, hemodynamics and mental status; and approaches to weaning including partial ventilator support, controlling factors that increase carbon dioxide levels, and assessing readiness through a rapid shallow breathing index. The goal is to allow patients to gradually interact more with the ventilator as their condition improves and be successfully weaned off mechanical ventilation through a structured process involving trials, communication and ensuring patient stability.
Pediatric ARDS is a common cause of respiratory failure in children. It is defined by acute onset hypoxemia that cannot be explained by cardiac failure, with bilateral lung opacities on chest imaging. Management involves controlling the underlying cause, lung protective ventilation with low tidal volumes, permissive hypercapnia, prone positioning, and consideration of recruitment maneuvers, HFOV, surfactant, inhaled nitric oxide, or ECMO in severe cases. Noninvasive ventilation may be tried initially for mild disease but intubation is often required for more severe pediatric ARDS. The goals of management are to maintain adequate oxygenation and ventilation while minimizing ventilator induced lung injury.
capnography refers to the noninvasive measurement of the partial pressure of carbon dioxide (CO2) in exhaled breath expressed as the CO2 concentration over time. The relationship of CO2 concentration to time is graphically represented by the CO2 waveform, or capnogram . Changes in the shape of the capnogram are diagnostic of disease conditions, while changes in end-tidal CO2 (EtCO2), the maximum CO2 concentration at the end of each tidal breath, can be used to assess disease severity and response to treatment. Capnography is also the most reliable indicator that an endotracheal tube is placed in the trachea after intubation.
This document discusses mechanical ventilation waveforms. It begins by stating the objectives are to discuss commonly used waveforms, their applications, and combined waveforms. It then provides an outline and introduction on waveforms and how they represent ventilator data graphically over time or against each other. The majority of the document discusses specific commonly used waveforms including pressure-time, flow-time, and volume-time curves and how to interpret each to evaluate the patient and ventilator settings.
This document discusses anesthesia considerations for patients with respiratory diseases. Key points include:
- Patients with respiratory diseases like COPD are at higher risk for postoperative pulmonary complications. Careful preoperative evaluation and optimization is important.
- General risks include older age, smoking history, and type/duration of surgery. Regional anesthesia can help reduce risks when possible.
- Intraoperatively, strategies like lower tidal volumes, PEEP, and careful extubation can help. Postoperatively, techniques like incentive spirometry and ambulation aid lung expansion.
- Diseases discussed in detail include COPD, asthma, bronchitis, emphysema, and restrictive diseases. Management aims to address issues like hypo
1) The document discusses various physiologic variables that can predict a patient's readiness to be weaned from a mechanical ventilator, including the rapid shallow breathing index, maximal inspiratory pressure, and compliance.
2) It contrasts approaches to weaning patients such as a spontaneous breathing trial using T-piece trials or low levels of pressure support, and describes criteria for indicating a successful spontaneous breathing trial.
3) Common reasons for weaning failure include respiratory failure that has not improved, organ system dysfunction, low oxygenation or ventilation status, and lack of an intact airway protective mechanism.
Cardiac output can be measured through various invasive and non-invasive methods. The pulmonary artery catheter using thermodilution is still considered the gold standard but is invasive. Minimally invasive methods include lithium dilution, pulse contour analysis devices, esophageal Doppler, and transesophageal echocardiography. Non-invasive methods include partial gas rebreathing, thoracic bioimpedance, and Doppler ultrasound. The ideal monitor is accurate, continuous, non-invasive and provides reliable measurements during different physiological states.
This document discusses ventilation in obstructive airway diseases. It provides indications and contraindications for non-invasive ventilation (NIV) including criteria such as respiratory rate greater than 25 breaths per minute and moderate to severe respiratory acidosis. NIV can be used to support patients with acute exacerbations of COPD or asthma to reverse respiratory failure. Ventilator settings aim to support gas exchange, reduce work of breathing, and prevent complications. Dynamic hyperinflation can cause auto-PEEP which increases workload and impairs hemodynamics. Settings to treat auto-PEEP include increasing expiratory time, reducing tidal volume, and applying external PEEP.
This document provides an overview of difficult airway management in the ICU. It discusses factors that can lead to difficult intubation in ICU patients such as remote location, unstable physiology, and patient factors. It describes different techniques for managing the difficult airway including anticipated difficult airways, unanticipated difficult airways, and cannot intubate/cannot ventilate scenarios. Equipment for difficult airways is outlined including video laryngoscopes, fiberoptic scopes, supraglottic airway devices, and surgical airway options like needle cricothyroidotomy. Pre-oxygenation techniques and adjuncts to improve laryngoscopy views are also summarized.
Ultrasonography evaluation during the weaning processFadel Omar
Ultrasonography can be useful for assessing cardiac function, diaphragm mobility, pleural effusions, and lung aeration during the mechanical ventilation weaning process. Assessment of left ventricular diastolic function, diaphragm excursion and thickening fraction, size of pleural effusions, and lung ultrasound score can provide information on risks of weaning failure and identify issues like cardiogenic pulmonary edema. Removal of moderate or large pleural effusions may improve chances of successful weaning in patients with respiratory dysfunction. Lung ultrasound before and after spontaneous breathing trials can detect loss of lung aeration associated with post-extubation respiratory issues.
Recruitment Maneuvers in ARDS Dr Chennamchetty Vijay KumarVizae Kumar Chennam
This document discusses recruitment maneuvers for mechanically ventilated patients. It begins with a case study of a patient presenting with respiratory failure. It then provides definitions and the physiological rationale for recruitment maneuvers, including how alveolar collapse occurs in ARDS. Different types of recruitment maneuvers are described, as well as factors that influence their effectiveness. Clinical trials on recruitment maneuvers are summarized, which found no significant reduction in mortality but some improvement in secondary outcomes. Limitations of recruitment maneuvers are discussed, such as potential hemodynamic effects. The document concludes with emphasizing the complexity of lung recruitment and ongoing controversies regarding recruitment maneuvers.
This document discusses the physiology of positive pressure ventilation. It covers:
- The goals and types of mechanical ventilation including positive and negative pressure ventilation.
- Key concepts including pressure gradients, time constants, airway pressures, and the effects of PEEP.
- Modes of ventilation including volume-controlled, pressure-controlled, and how they differ in terms of triggers, limits, and cycling.
- Waveforms including pressure, volume, and flow and how they are used to assess ventilation.
The document provides an overview of the fundamental physics and physiology principles underlying mechanical ventilation.
1) ARDS is characterized by hypoxemia, bilateral lung infiltrates, and respiratory failure not fully explained by cardiac failure. The Berlin definition classifies ARDS as mild, moderate, or severe based on oxygenation levels.
2) Management of ARDS focuses on treating underlying causes, preventing complications, and using ventilator strategies like low tidal volume ventilation to prevent ventilator-induced lung injury.
3) Other ventilator strategies discussed include prone positioning, neuromuscular blockade, recruitment maneuvers, and extracorporeal membrane oxygenation for severe cases, though evidence on benefits is mixed.
This document provides an overview of non-invasive ventilation (NIV). It discusses the history of NIV, types of ventilators and modes used, interfaces, indications and contraindications. Guidelines are provided on how to start and monitor NIV, including adjusting settings based on patient response. Advantages, disadvantages and complications of NIV are reviewed. Applications of NIV for specific clinical conditions like COPD exacerbation and acute cardiogenic pulmonary edema are covered. The document aims to educate medical professionals on best practices for administering and monitoring patients receiving NIV treatment.
1. Separation from cardiopulmonary bypass (CPB) after cardiac surgery is a gradual transition from full mechanical support to spontaneous heart and lung function.
2. During weaning, transesophageal echocardiography provides information to guide decision making. Weaning involves preparing the patient, checking readiness, gradually reducing bypass support while monitoring cardiac function, and treating any failure to wean.
3. Causes of failure to wean include left ventricular failure from issues like graft failure, ischemia, or valve problems, right ventricular failure from causes such as pulmonary hypertension or ischemia, and inappropriate vasodilation from various potential issues.
Critically ill patients requiring noninvasive or invasive ventilation often present to emergency departments, and due to hospital crowding and constrained critical care services, may remain in the emergency department for a prolonged duration. Compared with their intensive care unit counterparts, emergency department clinicians may have variable exposure to management of this patient population and may lack knowledge and expertise, particularly in their
longitudinal management beyond initial stabilization. This
review has discussed several key aspects of management
of noninvasive and invasive ventilation, with a particular emphasis on initiation and ongoing monitoring priorities,
and focused on maintaining patient safety and improving
patient outcomes.
This document discusses ventilation strategies for a patient with acute respiratory distress syndrome (ARDS). It provides details of the patient's initial presentation and management, including mechanical ventilation settings. It describes the rationale for using low tidal volume ventilation to minimize ventilator-induced lung injury. The patient required aggressive management for sepsis and hypoxemia including recruitment maneuvers and increasing PEEP and mean airway pressures. Despite these efforts, the patient could not be weaned from high FiO2 and developed multi-organ failure and died. The document recommends using low tidal volumes, limiting end-inspiratory pressures, adequate PEEP, and considering recruitment maneuvers to optimize ventilation in ARDS.
Non-invasive ventilation (NIV) provides ventilatory support without intubation through a non-invasive interface like a mask. It is used initially to treat type 2 respiratory failure and prevent need for mechanical ventilation. Benefits include avoiding complications of intubation and improving outcomes by reducing mortality, morbidity, ICU/hospital stay, and costs. NIV is appropriate for patients with acute or acute on chronic respiratory failure who are cooperative, hemodynamically stable, and have an adequate cough reflex. Factors determining success include careful patient selection, skilled application and monitoring, and timely transition to invasive ventilation if needed.
The document discusses anesthesia considerations for thoracoscopy and VATS procedures. It covers preoperative assessment and optimization, intraoperative anesthetic management including lung isolation techniques, ventilation strategies, positioning, and management of issues like hypoxemia. Protective lung ventilation principles with low tidal volumes, PEEP, and recruitment maneuvers are emphasized for lung protection during one-lung ventilation.
Noninvasive ventilation (NIV) refers to ventilatory support without an invasive artificial airway such as an endotracheal or tracheostomy tube. NIV can be delivered via nasal or oronasal masks connected to positive pressure ventilators. The document traces the history of ventilation from ancient times to modern NIV techniques. It describes various interfaces, modes of ventilation including CPAP, contraindications, and suitable clinical conditions for NIV support such as COPD exacerbations and cardiac pulmonary edema.
The document discusses ventilation and different modes of noninvasive ventilation. It provides details on:
1) How ventilation works through pressure differences that cause air to flow into and out of the lungs. Different factors like resistance and Boyle's law impact this process.
2) The history and development of noninvasive ventilation, from early negative pressure devices to current use of positive pressure ventilation delivered noninvasively through masks.
3) Modes of noninvasive positive pressure ventilation including volume ventilation, pressure ventilation, bilevel PAP, and CPAP. The benefits and limitations of noninvasive ventilation are also summarized.
This document discusses respiratory failure and mechanical ventilation. It covers three key areas: causes of respiratory failure including neurological, muscular and airway issues; criteria for assessing readiness to wean from ventilation including adequate oxygenation, hemodynamics and mental status; and approaches to weaning including partial ventilator support, controlling factors that increase carbon dioxide levels, and assessing readiness through a rapid shallow breathing index. The goal is to allow patients to gradually interact more with the ventilator as their condition improves and be successfully weaned off mechanical ventilation through a structured process involving trials, communication and ensuring patient stability.
Pediatric ARDS is a common cause of respiratory failure in children. It is defined by acute onset hypoxemia that cannot be explained by cardiac failure, with bilateral lung opacities on chest imaging. Management involves controlling the underlying cause, lung protective ventilation with low tidal volumes, permissive hypercapnia, prone positioning, and consideration of recruitment maneuvers, HFOV, surfactant, inhaled nitric oxide, or ECMO in severe cases. Noninvasive ventilation may be tried initially for mild disease but intubation is often required for more severe pediatric ARDS. The goals of management are to maintain adequate oxygenation and ventilation while minimizing ventilator induced lung injury.
The document discusses various topics related to mechanical ventilation including:
1. Ventilation strategies for acute respiratory distress syndrome (ARDS) including low tidal volumes, optimal positive end-expiratory pressure, and prone positioning.
2. Ventilation modes and settings should be tailored to the individual patient's condition and aim to prevent ventilator-induced lung injury.
3. Non-invasive ventilation can be considered for certain patients with COPD or asthma to avoid intubation if criteria are met.
Ventilatory support in special situations balamugeshDang Thanh Tuan
This document summarizes ventilation strategies for different clinical situations including ARDS, COPD, asthma, and bronchopleural fistula. It discusses ventilator settings such as tidal volume, PEEP, FiO2 and prone positioning that are recommended for ARDS. Non-invasive ventilation options for COPD and asthma exacerbations are also reviewed. Intubation criteria and strategies to deliver aerosol treatments during mechanical ventilation are provided. Managing air leak through bronchopleural fistula with techniques like differential lung ventilation or chest tube use is outlined.
This document discusses the management of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). It provides definitions of ALI and ARDS, lists potential causes, and outlines a ventilator strategy focusing on lung protection with low tidal volumes and appropriate positive end-expiratory pressure (PEEP). Monitoring, complications, refractory hypoxia strategies including prone positioning, and general patient care are also addressed.
A 58-year-old smoker presents with worsening shortness of breath and difficulty reclining. On examination, he is in respiratory distress using accessory muscles and has wheezes and rhonchi bilaterally, suggesting airway obstruction. He likely has an acute exacerbation of COPD. The best initial treatments are oxygen, bronchodilators, and steroids to improve his condition.
1) Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition caused by injury to the lungs. It can result from direct lung injury, such as pneumonia, or indirect injury, like sepsis.
2) ARDS progresses through exudative and proliferative phases characterized by fluid accumulation and scarring in the lungs. This impairs gas exchange and causes respiratory failure.
3) Mechanical ventilation is used to treat respiratory failure but can further damage the lungs if not done carefully. The ARDSNet trial showed using low tidal volumes of 6 ml/kg improved survival compared to larger volumes.
Asthma-Non-invasive ventilation critical care seminar.pptxMisganawMengie
This document discusses the use of non-invasive ventilation (NIV) for respiratory failure. It begins by explaining what NIV is and the different types of respiratory failure it can treat. It then describes how NIV works to reduce work of breathing and improve gas exchange. The document outlines the advantages and disadvantages of NIV as well as conditions it can be used for and contraindications. It provides details on different NIV modes, protocols for setup, and guidelines for monitoring patients. Lastly, it discusses the management of acute severe asthma, including indications for mechanical ventilation and initial ventilation goals.
The document provides information about acute respiratory distress syndrome (ARDS). It begins with a brief history of ARDS and provides the clinical definition. It describes the diagnostic criteria and etiology, including that most cases are caused by sepsis, pneumonia, or trauma. It then discusses the normal lung physiology and pathophysiology of ARDS, which involves three phases: exudative, proliferative, and fibrotic. The management section outlines the principles of therapy to provide adequate gas exchange while avoiding secondary injury, including mechanical ventilation protocols, fluid management, and other strategies. It concludes with a discussion of prognosis and recent advances in ARDS management such as protective ventilation strategies.
1. The document discusses acute respiratory distress syndrome (ARDS), describing its pathophysiology, causes, diagnosis, treatment and prognosis.
2. ARDS is characterized by hypoxemia, reduced lung compliance and diffuse pulmonary infiltrates leading to respiratory failure. Common causes include sepsis, pneumonia and trauma.
3. Treatment involves treating the underlying cause, supportive care including mechanical ventilation with low tidal volumes, and managing fluid levels and oxygenation. Prognosis depends on severity of illness, with reported mortality ranging from 41-65%.
The document discusses modern ventilator management. It covers who needs mechanical ventilation and different ventilator modes like ACV, SIMV, and APRV. It discusses setting ventilator parameters like PEEP, oxygen levels and how patient position impacts lung perfusion and ventilation. The document also reviews prerequisites and methods for discontinuing ventilator support, recommending once-daily spontaneous breathing trials.
This document discusses modern ventilator management. It begins by outlining the objectives of identifying who needs mechanical ventilation, understanding different ventilation modes, assessing patients and settings. It then covers who needs ventilation, positioning effects, common modes like ACV and PEEP settings. Advanced modes like APRV are described along with prerequisites and methods for discontinuing ventilation support like spontaneous breathing trials. The key topics of identifying patients for ventilation, understanding different modes, settings and discontinuing support are covered.
Mechanical ventilation provides respiratory support for patients unable to breathe on their own. This document provides guidelines for ventilating pediatric patients, including initial ventilator settings based on age. It describes managing gas exchange issues like hypoxemia and hypercarbia by adjusting settings like FiO2, PEEP, rate and tidal volume. Weaning criteria include an FiO2 requirement of 40% or less and improving clinical status. Complications of ventilation include barotrauma, nosocomial infections, and decreased organ perfusion. The document provides criteria for when not to ventilate patients with very poor prognoses and outlines nursing care responsibilities.
PATHOGENESIS AND MANAGEMENT OF ARDS-2.pptxdevanshi92
1) ARDS results from increased lung vascular permeability leading to accumulation of fluid and protein in the lungs. This causes diffuse pulmonary edema and hypoxemia that is resistant to oxygen therapy.
2) Treatment involves identifying and treating the underlying cause, using mechanical ventilation with low tidal volumes and limiting inspiratory pressures to prevent further lung injury, and maintaining adequate oxygen levels through techniques like PEEP.
3) The ARMA trial showed that a ventilation strategy using low tidal volumes and plateau pressures reduced mortality in ARDS patients, establishing this approach as the standard of care.
1. The document discusses mechanical ventilation, including its history, principles, objectives, modes, settings, complications, and clinical applications.
2. Key points include the various modes of mechanical ventilation like volume controlled, pressure controlled and pressure support. It also outlines objectives, settings, and safety principles of mechanical ventilation.
3. Complications discussed are ventilator-induced lung injury, ventilator-associated pneumonia, and physiological and artificial airway complications. Clinical applications include indications, contraindications and criteria for use of non-invasive positive pressure ventilation.
The document discusses mechanical ventilation, including definitions, types, indications, settings, complications, and nursing management. Mechanical ventilation is a method of positive or negative pressure breathing assistance used when patients cannot maintain adequate oxygen or carbon dioxide levels on their own. The major types are negative pressure ventilation and positive pressure ventilation. Settings control factors like respiratory rate, tidal volume, oxygen concentration, and PEEP. Complications can include hypotension, pneumonia, and increased intracranial pressure. Nurses monitor patients, ventilator settings and alarms, and prevent complications like infection through interventions such as oral care.
indications for intubation and extubation. MV.pptxJoe Poblete
The document discusses mechanical ventilation and its indications, objectives, and settings. Mechanical ventilation provides artificial respiration through a breathing machine when the lungs are not functioning properly. It serves as the energy source for inspiration and provides warmed and humidified gas to the airway. The general goal is to maintain spontaneous breathing whenever possible to prevent muscular atrophy. The document outlines various modes of mechanical ventilation including ACMV, SIMV, PCV, and PSV and provides typical settings for each.
This document provides an overview of respiratory failure, including its definition, types, causes, patient presentation, investigations, management, and complications. There are four types of respiratory failure: type I involves hypoxemic failure due to issues with oxygenation; type II involves hypercapneic failure due to ventilation issues; type III occurs perioperatively due to lung collapse; and type IV is due to respiratory muscle hypoperfusion in shock. The management of respiratory failure involves treating the underlying cause, providing oxygen support, and potentially mechanical ventilation. Outcomes depend on the severity of acidosis and underlying illnesses.
Mechanical ventilation is a method used to assist or replace spontaneous breathing by using physical devices. It can be used to treat acute respiratory failure, provide prophylactic support, or induce hyperventilation. There are two main types: negative pressure ventilation which applies lower pressure outside the chest and positive pressure ventilation which applies higher pressure inside the lungs. Common ventilator modes include assist control, SIMV, pressure control, and pressure support. Proper monitoring, settings, and care are needed to prevent complications while the patient is ventilated.
The document compares mechanical ventilation strategies for acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). For ARDS, the strategies aim to prevent volutrauma and barotrauma by limiting tidal volumes and airway pressures. Positive end-expiratory pressure (PEEP) is used to recruit alveoli and keep airways open. For COPD, the goal is to increase oxygen levels while allowing longer expiration to prevent auto-PEEP. Non-invasive ventilation can help both conditions but invasive ventilation may be needed for severe COPD exacerbations or if non-invasive methods fail.
8. Prolonged sedation, reduces
respiratory drive and prolongs
ventilation. Psychological dependence
on the ventilator follows prolonged
usage.
A number of factors will reduce central
respiratory drive. As CO2 is the main
stimulus for ventilation, the pt’s PaCO2
must be returned to a normal level.
Metabolic or respiratory alkalosis
reduces hydrogen ion concentration in
the brainstem, and thus the stimulus to
breath.
For weaning the patient must be awake
and co-operative and able to protect
his airway.
9.
10. It is essential to rule out the possibility
of a persistent neurological injury such
a phrenic nerve palsy, due to surgery.
Some drugs such as aminoglycosides
can mimic NMBs.
Prolonged critical illness may lead to
the development of a critical illness
polyneuropathy, due to axonal
degeneration.
11. Muscular atrophy due to
malnutrition, prolonged muscle
relaxants or critical illness myopathy
may limit weaning.
12.
13. Chest Wall – flail chest: is the pain under
control?
Does the patient have a compliant chest
wall?
If the patient has to work hard just to lift
the chest wall - for example extensive
edema, large fat pads, tight
dressings, increased abdominal pressure -
due to bowel swelling, packs, blood
etc, then weaning will be very difficult.
Pleural effusions – are they present, can
they be drained? Does the patient have a
chest drain in – is there much coming in.
14. Airways – airway obstruction – mucus
plug, excessive secretions or
bronchospasm? Is there laryngeal edema
Abdomen: does the patient have a
compliant abdominal surface. The
presence of ascites, distended
bowel, abdominal hypertension, packs or
tight surgical dressings may interfere with
ventilation.
15. Avoid being drawn into the “minute volume
looks”
the ability to ventilate is related to
alveolar ventilation, not minute ventilation.
16. “Why A patient's PaCO2 so high when
he has a minute ventilation of 20 liters
per minute?"
17. Clearance of carbon dioxide is determined
by the alveolar ventilation and the
physiologic dead space.
This is a common trap to fall into:
confusing alveolar ventilation (difficult to
measure) with minute ventilation (always
measured). The difference between the
two is determined by the anatomical dead
space.
BEWARE OF TACHYPNEA WITH SMALL
TIDAL VOLUMES
18. Patient A
taking 20 breaths of 500ml tidal
volume.
Patient B
taking 50 breaths of 200ml tidal
volume.
19. Pt. A has a normal blood gas.
Pt. B has a significant respiratory
acidosis.
Vd/Vt ratio
Patient A Vd/Vt < 30%
Patient B Vd/Vt 75%.
????
In the case of patient B, 75% of his
respiratory effort is being
wasted, leading to severe muscular
fatigue and acidosis.
20. Alveolar dead space:
A patient can be receiving tidal
volumes of 500ml and still have a dead
space / tidal volume ratio of 75%.
How???
Alveolar dead space is caused by
increased volume of zone 1 (zone 1 is
where alveolar pressure exceeds the
perfusion pressure to the lung unit:
alveoli are ventilated but not perfused):
21. Zone 1:
PA > Pa > Pv
Zone 2:
Pa > PA > Pv
Zone 3:
Pa > Pv > PA
22.
23. Hypoperfusion - low pulmonary
blood volume-pressure leads to
underperfusion of non dependent
lung segments.
Overdistension of lung by
excessive PEEP
Vd/Vt = PaCO2 - PetCO2/PaCO2
27. The patient is able to ventilate
The patient is able to oxygenate
The patient is able to protect his
airway
28. Alveolar Ventilation keeps
PaCO2 < 50 mmHg
Production of CO2 can be controlled by
reducing the carbon load in the diet (high
fat),
minimize agitation,
pain,
fever,
shivering
muscle workload.
29. diffusion abnormalities,
ventilation-perfusion mismatch,
dead space and shunt
persistent lower respiratory tract
infection,
alveolar edema,
airway/lobar collapse,
lung fibrosis
30.
31. The commonest cause of airway collapse
is absorption atelectasis, distal to mucus
plugs
Good quality of chest physiotherapy is
required to mobilize secretions
If the patient is requiring moderate to high
levels of PEEP to oxygenate , then
weaning is unlikely.
32. A source of ventilation-perfusion
mismatch: this leads to hypoxemia and
hypercarbia.
Tremendously difficult to reinflate:
leading to a huge increase in the work
of breathing & oxygen consumption.
33.
34.
35.
36. How much to give ?
Insufficient PEEP is of little benefit.
Excessive PEEP problems:-
barotrauma
wasted ventilation
Increased intrathoracic pressure
Ideal level of PEEP is that which prevents
derecruitment of the majority of
alveoli, while causing minimal over
distension
37. Auto-PEEP is gas trapped in alveoli at
end expiration, due to inadequate time
for expiration, bronchoconstriction or
mucus plugging.
It increases the work of breathing.
39. Controlled Ventilation
Partial ventilator
support
The objective of PVS is to allow the
patient to interact with the ventilator as
the neuro-mechanical cause of respiratory
failure resolves. The disease process and
ICU interventions (sedation), do not allow
for immediate movement from full support
to extubation.
40. Although partial support modes are
widely used, there is no evidence that
they are superior to multiple daily T-
piece trials. The most effective method
of PVS is targeted pressure support.
SIMV + PS
Pressure Assist control
PSV
41. Ensure that patient is suitable for
weaning
Communicate to the patient
Conduct the trials early in the
morning, when the patient is fully
rested and there is a full supporting
staff available.
During these trials the patient should
be awake and co-operative, afebrile and
on minimal pressor support
42. Place the patient in the upright or semi-
upright position and explain what you
are attempting to do.
Suction out the tube, airway and
oropharynx.
44. Criteria Description
Objective o Adequate oxygenation (eg, PaO2 >60 mm Hg on FIO2 > 0.4; PEEP <5cm
measurements H2O; PaO2/FIO2 >150–300);
o Stable cardiovascular system (HR <140; stable BP; (no or minimal
vasopressors)
o Afebrile (temperature < 38 C)
o No significant respiratory acidosis
o Adequate hemoglobin
o Adequate mental status (arousable, no continuous sedative Infusions)
o Stable metabolic status (acceptable electrolytes)
Subjective
clinical o Resolution of disease acute phase; physician believes discontinuation
assessment possible; adequate cough reflex
45.
46.
47. Two parts to weaning:
weaning to partial ventilator support
weaning to discontinuation.
There is little evidence that partial
modes are more effective than T-piece
trails.
Of these modes, pressure support is
the best.
48. If it is possible to wean a patient to
extubation, but the patient cannot
protect his airway.
It is best to perform tracheotomy.
49. It may be difficult to wean a patient if
ongoing inflammatory processes
persist in the lungs:
consolidation
fibrosis
auto-PEEP
diffusion defects
50. A 77 year old male F/c Lapratomy.
Complicated by perioperative
MI, systemic sepsis required insertion of a
pulmonary artery catheter, volume loading
and vasopressors, and moderate renal
dysfunction, with s.creatinine 3.3.
He is now at 14 days postop on ventilator
Currently he is difficult to arouse, on a
sedation of fentanyl 50μg/hr & medazolam
His temperature is 37.8.
Pulse is 76 and regular, B.P. is 130/70 and
CVP is 12.
51. lungs are clear on auscultation, CXR reveals
some patchy infiltrates, atelectasis and a left
sided pleural effusion. On SIMV rate
8, pressure support 16 and PEEP 5
cmH2O, FIO2 35% . ABG :- pH 7.52, PaO2
72, PaCO2 44, BE +8, SaO2 94%.
Abdomen is tense, with a wound closed with
tension sutures and two drains, currently
draining very little.
LFT: normal except for an albumin of 1.6 . He
has edema of lower limb, sacral and scrotal
area.
His fluid balance is even over the past five
days.
Hb 8.1, WBC 18.5, Plat 1.2 Lac, Na 148, K
3.1, Urea37,Creat 1.2, MgSO4 3.2, PO4 1.5, Ca
2.0.
The patient is completing a 14 day course of
ampi., genta. & metronidazole.
52. CNS – he remains sedated with
medazolam and fentanyl. These will both
reduce level of consciousness and impair
central respiratory drive. These agents
must be aggressively weaned.
PNS – although he has only been
ventilated for two weeks, he is doing little
work himself, and may have some
muscular atrophy. In addition, the
combination of a low serum
potassium, magnesium and phosphate
need to be supplemented for muscular
function.
53. CVS – the patchy infiltrates on CXR and
the history of MI are worrisome, this
indicates that this patient will not easily
tolerate the autotransfusion associated
with moving from positive to negative
pressure ventilation. It is essential to do
an echocardiogram, assess cardiac
performance and consider the use of an
agent that remodels the ventricle and
reduced preload and afterload – an ACE
inhibitor. We must be cautious in this
circumstance with the history of renal
failure. Alternative therapies would be the
introduction of either nitrates or
dobutamine in the hours peri-extubation.
54. Renal – renal function is reasonably good now,
metabolic alkalosis indicate sodium
bicarbonate use – seen in the high serum
sodium. This alkalosis can be corrected with
judicious use of sodium chloride (the chloride
will correct the alkalosis by returning to
electro-neutrality) or increasing enteral free
water delivery.
Gastrointestinal/Abdomen – a tense tight
abdomen will interfere with diaphragmatic
excursion, and thus respiratory mechanics.
We have little control over this. It is worth
asking, nonetheless, with a tense abdomen
and nothing draining, if the drains are
blocked. Does the patient have ascites? If so,
it may be worth draining this to reduce intra-
abdominal pressure.
55. Extremities – peripheral edema and a low
serum albumin, as the patient probably also
has soggy lungs, from sepsis induced
capillary leak (low oncotic pressure and fluid
extravascation). There is little that can be
done about this edema, the fact that it is
resistant to diuretics is interesting. Has the
patient been given adequate prophylaxis
against deep venous thrombosis and
pulmonary embolism?
Pulmonary function – the x-ray findings
indicate patchy consolidation (difficult to
oxygenate) and a pleural effusion (difficult to
ventilate). The effusion can be drained if
necessary. Think for a possible nosocomial
pneumonia – because of persistent
leucocytosis, lung infiltrates and a low grade
temperature.
56. The patient has not been covered for
pseudomonas or MRSA pneumonia, and it
is essential to rule out this possibility by
performing a broncho-alveolar lavage at
this time. How long have the pt’s lines
been in – is that the source?
This patient will probably tolerate a
pressure support mode of ventilation fairly
well, although his electrolytes and acid
base status require correction. If there is
no movement towards minimal ventilator
settings within 48 hours, a prolonged
wean is probably likely (due to low
physiological reserve) and the patient will
require a tracheostomy.
57.
58. Cardiovascular – pulmonary edema due to left
ventricular failure or volume overload decreases
lung compliance and will make weaning more
difficult. When mechanical ventilation is
discontinued, significant physiological changes
occur which will influence cardiovascular
performance: change from positive pressure to
negative pressure ventilation, reduced mean
intrathoracic pressure, increased preload and
afterload. This may lead to critical loading of
myocardial fibers and provoke ischemia – failure
and edema.
Gastroinestinal – recurrent aspiration
pneumonitis, ascites or abdominal wounds leading
to diaphgramatic splinting. Abdominal distension
or hypertension, for any reason (massive fluid
resuscitation, surgical packs etc), will reduce
chest wall compliance and lead to failure to
ventilate.
59. Nutrition -protein malnutrition leading to
muscular atrophy, which affects the
diaphragm and intercostals.
Acid base – metabolic alkalosis, particularly
due to use of diuretics reduces respiratory
drive. Conversely, muscles perform poorly in
an acidic environment. Metabolic acidosis is
caused by excessive amounts of measured
anions (chloride) or unmeasured anions
(lactate - from hypoperfusion), ketones and
renal acids.
Electrolytes–
hypophosphatemia, hypomagnesemia, hypokal
emia, hypocalcemia: these all affect muscular
function and protein metabolism.
60. Endocrine – muscle weakness due to
hypothyroidism or steroid induced
myopathy.
Oxygen delivery capacity – the
circulating hemoglobin concentration:
anemia increases respiratory drive and
cardiac output in order to maintain
oxygen delivery.
Pain control – it is very difficult to wean
patients who are in pain, particularly
from upper abdominal or thoracic
surgery or injuries. If a patient has a
flail chest, it may be necessary to
insert a thoracic epidural prior to
extubation
62. The Cuff leak test:
The ventilator is used in Assist Control mode
with a tidal volume of 10-12ml/kg. The expired
tidal volume is measured with the cuff inflated.
The cuff is then deflated and after elimination of
artefacts due to cough, four to six consecutive
breaths are used to compute the average value
for the expiratory tidal volume. The difference in
the tidal volumes with the cuff inflated and
deflated is the leak. A value of 130ml (12% of
inspiratory tidal volume) gave a sensitivity of
85% and a specificity of 95% to identify patients
with an increased risk of post extubation stridor.
63. Cough / Leak test: In spontaneously
breathing patients
The tracheal cuff is deflated and monitored
for the first 30 seconds for cough. Only
cough associated with respiratory
gurgling (heard without a stethoscope and
related to secretions) is taken into
account.
The tube is then obstructed with a finger
while the patient continues to breath. The
ability to breathe around the tube is
assessed by the auscultation of a
respiratory flow.
Editor's Notes
Approximately 50% of the time a patient spend on a mechanical ventilator is in the process of weaning
opposite way to which we commencement of mechanical ventilation.
ETT blockage, if no proper care.
The amount of sedatives used must be minimized and the patient wakened daily.
by using a nerve stimulator
Have you ever tried to inflate a completely deflated balloon: it’s really difficult to inflate initially, then you feel a give and the rest is a cinch! Inflating alveoli is like this. A more appropriate approach would be to let the balloon (alveolus) deflate to just above the point where inflation becomes easy (the lower inflection point of the pressure-volume curve), then reinflation is much less work. This is the concept behind CPAP
Increased intrathoracic pressure will have adverse effect on CVS
Less useful in Pt. on prolonged ventilation & in elderly.
Unless the patient is being ventilated for post-operative care, in which case the lungs are usually normal,
Describe how you would evaluate this patient for weaning from mechanical ventilation?