mechanical ventilators


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  • The goals of mechanical ventilation include: adjusting alveolar ventilation to bring pH and PaCO 2 within the patient’s normal range, improving oxygenation to acceptable levels given the age of the patient and disease process, and decreasing the work of breathing. Before we move on with our discussion of mechanical ventilation, we should take a look at how spontaneous breathing occurs.
  • Vital capacity – amount of air displaced by maximal exhalation. Minute ventilation -Volume of air expired per minute
  • Negative-pressure ventilation mimics spontaneous ventilation. A negative extrathoracic pressure applied to the chest wall increases the volume of the thoracic cage. This results in a negative intrathoracic pressure gradient and causes air to enter the lungs. One advantage of negative-pressure ventilation is that it requires no artificial airway. It is used mainly for chronic care of patients with neuromuscular disorders such as ALS, MS, etc. Some adult polio victims and kyphoscoliosis patients still use the iron lung. Other examples of negative-pressure ventilators are the pulmowrap and chest cuirass. Almost all ventilators currently being used in hospitals today are positive-pressure ventilators.
  • Combination of machine and spontaneous breath.mandatory breaths delivered when pt effort determine the TV and rate
  • used in the spontaneous breathing patient who may or may not be intubated. It can be administered also via face mask.
  • Let’s turn our focus to ventilator alarm management, including high and low airway pressure alarms, rate alarms, and volume alarms. Alarms warn the clinician about technical and patient conditions that can negatively impact the ventilator’s ability to provide support. Alarms can be audible and/or visual, depending on the severity of the alarm condition. Alarms can only provide warning if set appropriately. When a ventilator alarm is activated, the clinician needs to respond, identify the alarm parameter that has been violated, and institute corrective action. Since many different situations can cause an alarm condition, the clinician should employ a systematic approach to troubleshoot the problem. All clinicians need to be familiar with ventilator messages and alarms, and must be able to troubleshoot. If you can not readily identify the problem and the patient is in distress, disconnect the patient from the ventilator and provide manual ventilation.
  • mechanical ventilators

    1. 1. Mechanicalventilation
    2. 2. VentilationVentilation: Ventilation or breathing is the process of moving air into and out of the lungs.Mechanical ventilation: It is a process of giving artificial respiration through the device “Mechanical ventilator”.
    3. 3. Mechanical ventilator It is a device to inflate the lungs artificially by positive pressure.
    4. 4. Goals of Mechanical Ventilation Adjust alveolar ventilation pH, PaCO2 Improve oxygenation Assess with pulse oximetry Decrease work of breathing
    5. 5. Indications for mechanical ventilation  Cardiac diseases:- Cardiogenic shock.  Central Nervous system diseases:-  Cerebral trauma.  Cerebrovascular accident.  Spinal cord injury.
    6. 6.  Neuro muscular diseases:- Guillian –Barre syndrome. Multiple sclerosis. Poliomyelitis. Musculoskeletal diseases:- Kyphoscoliosis. Myasthenia gravis
    7. 7.  Others:- Trauma like rib fractures, head injury, facial trauma. Surgery like cardiac surgery, pulmonary and gastro intestinal surgery.
    8. 8. Clinical IndicatorsRespiratory assessment  Respiratory rate > 35 bpm  Negative inspiratory force < -25 cm H2O  Vital capacity < 10 ml/kg  Minute ventilation < 3 lpm or > 20 lpmGas exchange  PaO2 < 60 mm Hg with FiO2 > 50%  PaCO2 > 50 mm Hg (acute) and pH < 7.25
    9. 9. Types of Mechanical ventilators Negative-pressure ventilators Positive-pressure ventilators
    10. 10. Negative-pressure ventilators Negative pressure applied to chest wall increases the volume of the thoracic cage Mimics spontaneous ventilation Negative intrathoracic pressure gradient causes air to enter lungs No need for artificial airway Used mainly for chronic care of patients with neuromuscular disorders Examples: iron lung, pulmowrap, chest cuirass
    11. 11. Positive-pressure ventilators Intrathoracic pressure remains positive throughout respiration Force oxygen into the patients lungs through an endotrechial or tracheostomy tube to initiate respiration. Gas is distributed to non- dependent, less-perfused lung regions
    12. 12. Terms related to mechanicalventilation Respiratory rate (f): Number of breaths per minute (10 to 20 bpm). Tidal volume (VT): Volume of air inhaled /exhaled during each respiratory cycle ( 7 to 12 ml/kg). Minute ventilation (VE): Volume of air expired per minute. (VE=VT x f; 6 to 8L/min). Fraction of inspired oxygen(FIO2) - :amount of oxygen delivered to the patient. It can range from 21% (room air) to 100%.
    13. 13.  I:E Ratio - The inspiratory time compared to the expiratory time; I + E = total cycle time. (1:2 or less). Maximal Inspiratory pressure (MIP): Maximal negative pressure generated during inhalation.(15 -20cmH2O) Flow rate: Flow rate is the speed with which the tidal volume is delivered. (40 to 100 L/min).
    14. 14.  Cycling: what cycles, or changes, the ventilator from one phase of the respiratory cycle to the other. (volume, time, pressure, flow ). Positive end expiratory pressure(PEEP): keeps the air way open at the end of expiration ; 5 to 20 cms of H2O.
    15. 15. Classification of PPV Pressure cycled ventilators- ventilator pushes air until a preset pressure is reached. It is used for short periods such as in the post anesthesia care unit and for respiratory therapy.
    16. 16.  Volume- cycled ventilator: ventilators pushes air into the lungs until preset volume is delivered. Time-cycled ventilators: ventilators pushes air into lung until a preset time has elapsed. It is used primarily in pediatric and neonatal population.
    17. 17. Modes of Mechanical ventilationMode - how the machine will ventilate the patient in relation to the patients own respiratory efforts.The manner or method of support provided by the ventilator.
    18. 18. ASSIST CONTROL MODE(AC)• Most commonly• As a resting mode, in which ventilator takes over the work of breathing for the client.• Machine initiated and /patient initiated breaths.• A preset tidal volume and respiratory rate are delivered.
    19. 19. INTERMITTENT MANDATORY VENTILATION(IMV)  ventilator delivers a preset number of mechanical breaths.  allows the client to breath spontaneously in between with no assistance from the ventilator and at varying tidal volume.
    20. 20. SYNCHRONIZED INTERMITTENT MANDATORY VENTILATION (SIMV)  Delivers preset breaths that are synchronized with the patient’s spontaneous breaths.  preferred mode of weaning.
    21. 21. INVERSE RATIO VENTILATION (IRV) Normal inspiratory :expiratory ratio is reversed to 2:1 or greater (the maximum is 4:1). Longer inspiratory time increases the amount of air in the lungs at the end of expiration Improves oxygenation by reexpanding collapsed alveoli.
    22. 22. PRESSURE SUPPORT VENTILATION (PSV)  Preset pressure augments the patients spontaneous inspiration effort and decreases the work of breathing  Patient completely controls the respiratory rate and tidal volume.
    23. 23. CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP)  Keeps the alveoli open during inspiration and prevents alveolar collapse during expiration.  Used in the spontaneous breathing patient.  Used as a method for weaning patients from mechanical ventilation.  Improves gas exchange and improves oxygenation.  Normal range for CPAP is 5 to 15 cm of H2O.
    24. 24. Ventilator Alarms
    25. 25. Low pressure alarmtriggered by air leaks.Causes Patient disconnection Circuit leaks -mainline connections to humidifiers, filters Exhaled valve leaks: leaking valves, improperly connected valves Airway leaks: inadequate cuff inflation, leak in pilot balloon, rupture of tube /cuff
    26. 26. High airway pressureTriggered when resistance to ventilation is highCauses Ventilator problems:Inappropriate settings, excessive tidal volume, ventilator malfunction – rare Circuit problemsFluid pooling in circuit/ filter,kinking of circuit Endotracheal tube obstructionDue to sputum, kinking, biting Increased airway resistanceBronchospasm, decreased respiratory system compliance, decreased chest wall compliance
    27. 27. Apnea alarmsActivated when no exhalation is detected for a selected time period (e.g., 20 seconds)causes Patient apnea, disconnection, system leaks, inadequate machine sensitivity, Inappropriately set apnea parameters Can be accompanied by low pressure / low minute ventilation alarms
    28. 28. Complications of positive pressure ventilation. (PPV) Pneumothorax:Pleural pressure increases, and collapses the lung, causing Pneumothorax. Volu-pressure trauma/Barotrauma: the lung injury that occurs when large tidal volumes are used to inflate non compliant lungs (eg.ARDS). This results in alveolar fracture and movement of proteins and fluid into the alveolar spaces.
    29. 29.  Alveolar hypoventilation: caused by inappropriate ventilator setting, leakage of air from ventilator tubing or around ET tube and tracheotomy cuff, lung secretions or obstruction, and low ventilation perfusion ratio.
    30. 30.  Alveolar hyperventilation: Respiratory alkalosis can occur if the respiratory rate and tidal volumes are set too high. Ventilator-associated Pneumonia: because ET or tracheostomy tube bypasses normal upper air way defenses.
    31. 31.  Sodium and water imbalance: fluid retention occurs after 48 to 72 hours of PPV. It is associated with decreased urinary out put increased sodium retention. Fluid balance changes is due to the decreased cardiac output.
    32. 32.  Neurologic system: Increased intrathoracic pressure impedes venous drainage from the head. This increases the cerebral blood volume and causes a rise in intra cranial pressure. Gastro intestinal system: the ventilated patient is at the risk of developing stress ulcers and GI bleeding.
    34. 34. Hand Hygiene• Wash hands before  Use sterlium or direct contact. 40% of alcohol based infections are hand rub in transmitted by the between hands of Hospital staff procedure or as required.
    35. 35. Recording of vital signs:• Record vital signs. {Assess for hypotension, tachycardia, Tachypnoea }• Observe respiratory pattern & Auscultate lung sounds.• Observe for breathing pattern in relation to ventilatory cycle.• Assess for changes in mental status and LOC.• Continuous pulse oximetry.• Observe ABG for abrupt changes or deterioration as required.
    36. 36. Endotracheal tube care:• Introduce an oropharyngeal airway.• Maintain inflation of the cuff at 15 to 20 mmHg.• Institute Endotracheal suctioning as appropriate.• Administer humidified oxygen before suctioning to loosen secretions.• Change Endotracheal tapes every 24 hours.• Inspect the skin and oral mucosa.
    37. 37. S
    38. 38. • Stop feeding during 30 – 60 minutes before suctioning & chest physiotherapy.• Observe the type, color & amount of secretion, notify the changes.• Avoid drawing of arterial blood sample immediately after suctioning.• Watch for side effects: hypoxemia, bradycardia, hypotension.
    39. 39. Oral hygiene:• Provide careful oral hygiene• Apply lubricant to lips to prevent drying, cracking and excoriation.• Rotate the ET tube from one corner of mouth to the other side atleast every 24 hours.
    40. 40. Arterial Blood Gas analysis:• ABG reflects oxygenation adequacy of gas exchange in the lungs & Acid-base status.• Avoid taking sample immediately after suctioning, nebulisations and baging.• While drawing blood prevent entry of air in syringe.• Send immediately ABG sample to laboratory..
    41. 41. Maintain Nutritional needBasal energy expenditure calculation [Harris Benedict equation]Men : 66.47 + (13.75×W) + (5×H) - (6.76 ×A) Kcal/DayFem. : 65.51 + (9.56×W) + (1.58×H) - (4.68 ×A) Kcal/Day[W=Weight of Pt., H=Height of Pt., A=Age of Pt.]# High protein, High fat & Low carbohydrates diet can bebeneficial.# Add mineral supplements to the diet especially magnesium &phosphorus. These are essential for energy production &respiratory muscle function.
    42. 42. Positioning:• Turn and reposition the patient every 2nd hourly.• Positioning prevents complications such as pneumonia and atelectasis.
    43. 43. Personal hygiene:• Frequent oral hygiene must be done.• Eye care to be given every 4th hourly to prevent corneal ulcers and dryness of conjunctiva.• Provide skin care.• Provide catheter care using sterile technique.
    44. 44. Allaying anxiety & fear:• Explain all the procedures to the patient & relatives to win their confidence.• Talk and clear the doubts of patient & attainders. Never ignore there feelings.• Use therapeutic touch.• Encourage the family members to visit the patient as per hospital policy.
    45. 45. Care of ventilator circuit:• Keep the water level in humidifier in normal limit.• Humidification during mechanical ventilation required to prevent hypothermia, inspissations of airway secretions, destruction of airway epithelium & atelectasis.• A heated humidifier should be set to deliver an inspired gas temperature of 33 -/+ 2˚C.• The temperature of inspired gas should not exceed 37˚C at the airway threshold.• Sterile water should be used only.
    46. 46. • Condensation from the patient circuit should be considered infectious waste and should never be drained back in to the humidification reservoir.• Change the circuit when it is visibly soiled or mechanically malfunctioning.• Bacterial filters should not be used for more than 48 hours.• Use universal precautions when involved in circuit changes.
    47. 47. Care of ventilator alarms:• Never Shut Alarms Off – Alarm system must be activated and function at all time. It is acceptable to silence alarms for a preset delay while suctioning and during oxygen flush before suctioning.• If equipment failure is suspected and unable to determine the cause of alarm, Manually ventilate the patient with resuscitation bag until the problem is corrected.
    48. 48. VENTILATOR CARE BUNDLEAcc to IHI “bundle” is a group of evidence –based care components for a given disease that ,when executed together ,may result in better outcomes than if implemented individually.
    49. 49. VENTILATOR CARE BUNDLEIt includes : DVT prophylaxis(unfractioned heparin,elastic stockings,pneumatic compression,elevation of affected extrimity,gentle foot & leg exercise,fluid administration) GI prophylaxis(H2 blocker /proton pump inhibitor) Head of bed elevated to 30-45
    50. 50. Daily sedation vacation /daily spontaneousbreathing trialSkin safety (manage pressure,adequatenutrition,wound assessment & wound care)Fall prophylaxis