Updates in respiratory ICU


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Updates in respiratory ICU

  1. 1. Clinical Year Review :Critical Care By Gamal Rabie Agmy , MD , FCCP Professor of Chest Diseases ,Assiut University
  2. 2. Early tracheostomy versus Late Tracheostomy ◙ A 2005 meta-analysis of 5 studies (n=406) concluded that early tracheostomy reduced need for mechanical ventilation and ICU days. ◙ The Timing of Tracheotomy in Critically Ill Patients Undergoing Mechanical Ventilation:A Systematic Review and Meta-analysis of Randomized Controlled Trials Chest December 2011, Vol 140, No. 6 The timing of the tracheotomy did not significantly alter important clinical outcomes in critically ill patients
  3. 3. Novel Modes of Mechanical Ventilation Mashael Al-Hegelan, Neil R. MacIntyre Semin Respir Crit Care Med. 2013; 34(4):499-507.
  4. 4. Novel Strategies Addressing the Challenge of Balancing Gas Exchange versus VILI Airway Pressure Release Ventilation Airway pressure release ventilation (APRV, also known as BiLevel (Covidien, Boulder, CO) and Bi-phasic (CareFusion, Yorba Linda, CA), among other trade names) is a time-cycled, pressure-targeted form of ventilatory support. APRV is actually a variation of pressure-targeted SIMV that allows spontaneous breathing (with or without pressure support) to occur during both the inflation and the deflation phases. APRV uses a prolonged inspiratory time producing so-called inverse ratio ventilation (IRV with I:E ratios of up to 4 or 5:1). Spontaneous breaths thus now occur during this prolonged inflation period.
  5. 5. Novel Strategies Addressing the Challenge of Balancing Gas Exchange versus VILI High-frequency Oscillatory Ventilation High-frequency oscillatory ventilation (HFOV) uses very high breathing frequencies (120 to 900 breaths per minute [bpm] in the adult) coupled with very small tidal volumes (usually less than anatomical dead space and often less than 1 mL/kg at the alveolar level) to provide gas exchange in the lungs. The putative advantages to HFOV are twofold. First, the very small alveolar tidal pressure swings minimize cyclical overdistension and derecruitment. Second, a high mean airway pressure can also prevent derecruitment.
  6. 6. Novel Strategies Addressing the Challenge of Balancing Gas Exchange versus VILI Adaptive Support Ventilation Adaptive support ventilation (ASV) is an assist-control, pressure-targeted, time-cycled mode of ventilation that automatically sets the frequency-tidal volume pattern according to respiratory system mechanics to minimize the ventilator work. Conceptually, this minimal ventilator work may translate into minimal stretching forces on the lungs, which may, in turn, reduce VILI. .
  7. 7. Novel Modes Addressing Improved Patient Ventilator Interactions Volume Feedback Control of Pressure-Targeted Breaths As noted previously, pressure-targeted breaths with variable flow features often synchronize with patient flow demands better than fixed flow, volumetargeted breaths. A drawback to pressure targeting, however, is that a tidal volume cannot be guaranteed. The most common approach is to use a measured volume input to manipulate the applied pressure level of subsequent pressure-targeted breaths.When these breaths are exclusively supplied with time cycling, the mode is commonly referred to as pressureregulated volume control (PRVC), although there are several proprietary names (e.g., Autoflow [Draeger, Andover, MA], VC+ [Covidien], Adaptive Pressure Ventilation [Hamilton Medical Inc., Reno, NV]). When these breaths are supplied exclusively with patient-triggered, flow-cycling characteristics, the mode is commonly referred to as volume support (VS). Some ventilators will switch between these two breath types depending on the number of patient efforts. Both animal and human studies have shown that these feedback algorithms function as designed
  8. 8. Novel Modes Addressing Improved Patient Ventilator Interactions Enhancements on Volume Feedback Control of Pressure-targeted Breaths Airway occlusion pressure (P0.1), oxygen saturation (SpO2) and end-tidal CO2concentration have been incorporated into PRVC and VS mode-control algorithms to adjust either the target VT or the breath-delivery pattern. The one system that is commercially available uses end tidal CO 2 and respiratory rate along with the tidal volume to adjust the applied inspiratory pressure.[76] Known by the proprietary trade name SmartCare
  9. 9. Novel Modes Addressing Improved Patient Ventilator Interactions Proportional Assist Ventilation Proportional assist ventilation (PAV) is a novel approach to assisted ventilation that uses a clinicianset "gain" on patient-generated flow and volume.PAV uses intermittent controlled "test breaths" to calculate resistance and compliance.
  10. 10. Novel Modes Addressing Improved Patient Ventilator Interactions Neurally Adjusted Ventilatory Assistance Neurally adjusted ventilatory assistance (NAVA) utilizes a diaphragmatic electromyographic (EMG) signal to trigger and govern the flow and cycle of ventilatory assistan] The EMG sensor is an array of electrodes mounted on an esophageal catheter that is positioned in the esophagus at the level of the diaphragm. Ventilator breath triggering is thus virtually simultaneous with the onset of phrenic nerve excitation of the inspiratory muscles, and breath cycling is tightly linked to the cessation of inspiratory muscle contraction. Flow delivery is driven by the intensity of the EMG signal.
  11. 11. Transthoracic Chest Sonography in Critical Care
  12. 12. Ultrasound profiles. Lichtenstein D A , Mezière G A Chest 2008;134:117-125
  13. 13. Tissue pattern representative of Alveolar Consolidation Presence of hyperechoic punctiform representative images of air bronchograms Pleural effusion Lower lobe
  14. 14. Updates in ARDS Berlin definition: ―Acute lung injury‖ no longer exists. Under the Berlin definition, patients with PaO2/FiO2 200-300 would now have ―mild ARDS.‖ Onset of ARDS (diagnosis) must be acute, as defined as within 7 days of some defined event, which may be sepsis, pneumonia, or simply a patient’s recognition of worsening respiratory symptoms. (Most cases of ARDS occur within 72 hours of recognition of the presumed trigger.) Bilateral opacities consistent with pulmonary edema must be present but may be detected on CT or chest Xray. There is no need to exclude heart failure in the new ARDS definition
  15. 15. Updates in ARDS The new criterion is that respiratory failure simply be ―not fully explained by cardiac failure or fluid overload An ―objective assessment―– meaning an echocardiogram in most cases — should be performed if there is no clear risk factor present like trauma or sepsis
  16. 16. ARDS Severity PaO2/FiO2* Mortality** Mild 200 – 300 27% Moderate 100 – 200 32% Severe < 100 45% *on PEEP 5+; **observed in cohort
  17. 17. Mechanical Ventilation in ARDS: 2012 Review The protocol from the ARMA trial can serve as a guide to performing low tidal volume ventilation for mechanically ventilated patients with ARDS: Start in any ventilator mode with initial tidal volumes of 8 mL/kg predicted body weight in kg, calculated by: [2.3 *(height in inches - 60) + 45.5 for women or + 50 for men]. Set the respiratory rate up to 35 breaths/min to deliver the expected minute ventilation requirement (generally, 7-9 L /min) Set positive end-expiratory pressure (PEEP) to at least 5 cm H2O (but much higher is probably better), and FiO2 to maintain an arterial oxygen saturation (SaO2) of 88-95% (paO2 55-80 mm Hg). Titrate FiO2 to below 70% when feasible (though ARDSNet does not specify this). Over a period of less than 4 hours, reduce tidal volumes to 7 mL/kg, and then to 6 mL/kg.
  18. 18. Mechanical Ventilation in ARDS: 2012 Review Ventilator adjustments are then made with the primary goal of keeping plateau pressure (measured during an inspiratory hold of 0.5 sec) less than 30 cm H2O, and preferably as low as possible, while keeping blood gas parameters ―compatible with life.‖ High plateau pressures vastly elevate the risk for harmful alveolar distension (a.k.a. ventilator-associated lung injury, volutrauma).
  19. 19. Mechanical Ventilation in ARDS: 2012 Review If plateau pressures remain elevated after following the above protocol, further strategies should be tried: Further reduce tidal volume, to as low as 4 mL/kg by 1 mL/kg stepwise increments. Sedate the patient (heavily, if necessary) to minimize ventilator-patient dyssynchrony. Consider other mechanisms for the increased plateau pressure besides the stiff, noncompliant lungs of ARDS.
  20. 20. Mechanical Ventilation in ARDS: 2012 Review Permissive hypercapnia Permissive hypoxaemia
  21. 21. Limitations in Use of Plateau Pressure for ARDS Obesity — may have higher plateau pressures at baseline and during ARDS than non-obese patients. Esophageal manometry is considered superior to plateau pressures through its measurement of transpulmonary pressure, considered a more precise measure of potentially injurious pressures in the lung. Because it is invasive and the probes are prone to migration, esophageal manometry is not widely used.
  22. 22. High vs. Low PEEP in ARDS A strategy employing higher PEEP along with low tidal volume ventilation should be considered for patients receiving mechanical ventilation for ARDS. This suggestion is based on a 2010 meta-analysis of 3 randomized trials (n=2,229) testing higher vs. lower PEEP in patients with acute lung injury or ARDS, in which ARDS patients receiving higher PEEP had a strong trend toward improved survival. However, patients with milder acute lung injury (paO2/FiO2 ratio > 200) receiving higher PEEP had a strong trend toward harm in that same meta-analysis. Higher PEEP can conceivably cause ventilator-induced lung injury by increasing plateau pressures, or cause pneumothorax or decreased cardiac output.
  23. 23. Predicting Survival and Outcomes After ARDS A ―high risk‖ patient profile with a 52% mortality was identified of severe ARDS (PaO2/FiO2 ratio < 100) with either a high corrected expired volume >= 13 L/min, or a low static compliance < 20 mL/cm H2O. Reviews of ARDS outcomes suggest that most people who survive ARDS recover pulmonary function, but may remain impaired for months or years in other domains, both physically and psychologically.
  24. 24. Alternative / Rescue Ventilator Modes & ECMO in ARDS Some patients with severe ARDS develop severe hypoxemia or hypercarbia with acidemia despite optimal treatment with low-tidal volume mechanical ventilation. In these situations, alternative, salvage or ―rescue‖ ventilator strategies are often employed. Their common goal is to maintain high airway pressures to maximize alveolar recruitment and oxygenation, while minimizing alveolar stretch or shear stress. The most commonly used alternative ventilatory strategies are high-frequency oscillatory ventilation (HFOV) or airway pressure release ventilation (APRV or ―bilevel‖).
  25. 25. Surviving Sepsis Campaign: International Guidelines for Management of Severe Sepsis and Septic Shock: 2013 Critical Care Medicine, February 2013 • Volume 41 • Number 2 (http://links.lww.com/CCM/A615)
  26. 26. 1-early quantitative resuscitation of the septic patient during the first 6 hrs after recognition (1C); 2-blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); 3-administration of broad-spectrum antimicrobials therapy within 1 hr of recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy;
  27. 27. 4-reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); 5-infection source control with attention to the balance of risks and benefits of the chosen method within 12 hrs of diagnosis (1C); 6-initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1C)
  28. 28. 7-initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients) (1C); 8- norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥ 65 mm Hg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG);
  29. 29. 10- dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output or b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); 11-avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C);
  30. 30. 12-avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); 13-low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C)
  31. 31. 14-prone positioning in sepsis-induced ARDS patients with a Pao2/Fio2 ratio of ≤ 100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients 15-avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 hrs) for patients with early ARDS and a Pao2/Fio2 < 150 mm Hg (2C); 16-a protocolized approach to blood glucose management commencing insulin dosing when two consecutive blood glucose levels are > 180 mg/dL, targeting an upper blood glucose ≤ 180 mg/dL
  32. 32. 17-prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); 18-oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 hrs after a diagnosis of severe sepsis/ septic shock (2C);