Extubation

  • Just as important as knowing when and how to put a patient on a ventilator:
    • It is important to know when and how to remove them from this support:
      • Also known as “weaning
  • An adage from Critical Care is that preparation for extubation:
    • Starts as soon as the patient is intubated
  • With COVID-19:
    • The patients are generally requiring prolonged periods of intubation:
      • With many reports quoting 10 to 14 days
  • Regardless, the onus falls on the clinicians caring for any mechanically ventilated patient to assess the patient’s daily for signs of stability or improvement:
    • With any signs of improvement, assessment for extubation readiness should begin
  • Patients’ conditions should be assessed continually:
    • And once gas exchange and compliance improve:
      • The level of support can be reduced
  • For most patients, the first step in moving towards extubation readiness is:
    • To move from assist control ventilation to pressure support ventilation:
      • Pressure support ventilation:
        • Allows for spontaneous ventilation
          • The patient engages their diaphragm and sets their own respiratory rate, flow, and tidal volume
  • The following ventilator screen illustrates a patient who is ready to be changed to pressure support:
    • The patient was arousable with:
      • Lightening sedationhas
      • Has good pulmonary mechanics as indicated by:
        • The low PIP of only 22 with a TV of 400, has a low PEEP requirement, and is only on 50% FiO2
    • On these settings, the patient’s ABG was also reassuring, at 7.37/38/110:
      • Note:
        • In addition to changing to pressure support, the FiO2 could also be decreased to 40% given the more than adequate PaO
  • Once the patient has been placed on pressure support:
    • Physiological measurements including:
      • MIP (maximal inspiratory pressure),
      • frVt (respiratory frequency to tidal volume ratio, or
      • Rapid shallow breathing index
        • and others can be used to assess a patient’s readiness to wean
  • If the following criteria are met:
    • The patient should undergo a spontaneous breathing trial (SBT) to determine if they are ready to attempt extubation
  • Criteria for Performing Spontaneous Breathing Trial:
    • Improvement of underlying condition that led to intubation
    • Relative hemodynamic stability
      • HR < 130 beast per minute
      • Mean arterial pressure (MAP):
        • Adequately supported on a stable dose of vasopressors
      • Presence of a cough reflex:
        • Often elicited by suctioning
      • Burden of secretions that can be handled by cough strength:
        • Patients with a robust cough will be able to clear more secretions
      • Adequate oxygenation:
        • Usually SpO2 > 90% on 40% FiO2 and PEEP ≤ 8
      • Ability to maintain the current oxygenation status once extubated
      • Adequate ventilation:
        • pH > 7.3 with a PCO2 near baseline
        • Minute ventilation that a patient can maintain after extubated:
          • Usually < 12 L/min
      • Minimal ventilator settings:
        • On pressure support ≤ 10 cmH2O
        • On PEEP ≤ 8 cmH2O
        • Maintaining tidal volumes ≥ 5 mL/kg PBW
        • Respiratory rate < 35
        • FiO2 ≤ 50%
  • The following screen shows a patient on pressure support, 10/5 (10 cm H20 driving pressure over 5 cm H2O of PEEP):
    • This patient is marginal, as the tidal volume with 10 cm H2O of driving pressure is 400, which is acceptable, but the respiratory rate is 30:
      • The patient should be assessed for non-pulmonary causes of tachypnea:
        • Such as pain, anxiety/agitation, fever, etc
      • It is reasonable to decrease the pressure support of 10 cm H2O and reassess both the tidal volumes and respiratory rate
      • It is difficult to predict how patients will do; often the best course is to give them a trial and assess
  • Spontaneous breathing trials are used to:
    • Assess a patient’s readiness to wean by removing ventilation support for 30 minutes and evaluating the patient’s ability to breathe on their own during this time
    • There are many ways to perform SBTs, including:
      • Pressure support of 5/5, 0/5, and 0/0, as well as “T-piece trials” in which the patient is taken off the ventilator and supported with blow-by humidified oxygen
      • Each approach has its proponents, and institutional guidelines vary
        • The most important concept to consider is the available respiratory support options once the patient is intubated, and ensure they are able to pass with that level of support
  • Criteria for Passing Spontaneous Breathing Trials:
    • Clinical Appearance:
      • No evidence of respiratory distress:
        • Cyanosis
        • Diaphoresis
        • Accessory muscle use
        • Grimacing
    • Pulmonary mechanics
      • Ratio of respiratory rate : tidal volume:
        • Less than 105
      • Respiratory rate less than 30 breaths per minute
      • Tidal volume less than 5 mL/kg PBW
    • Oxygenation and ventilation:
      • SpO2 ≤ 50%
      • PaC02 ≤ 50mmHg or a
      • pH ≥ 7.3 or decrease in pH of ≤ 0.07
    • Hemodynamics:
      • Change in SBP to > 90 or < 180 mmHg
      • HR < 130 beats per minute
      • New dysrhythmias
  • The screen below demonstrates a patient who is doing well on an SBT:
    • They are on pressure support, 5/5, and have large tidal volumes of 735 mL, indicating good compliance
    • They are breathing at a slow rate of 14, and they are on a low FiO2 of 25%
    • This patient would be an excellent candidate for extubation, assuming there are no other barriers
  • If a patient’s spontaneous breathing trial is successful, the next step is to assess for other barriers to extubation
  • A helpful approach is to go head to toe:
    • Head:
      • Is the patient awake, following commands?
        • If not, does the clinician believe s/he will be able to cough and protect the airway?
      • Is the patient calm or agitated?
        • If agitated, does it seem related to the ETT?
        • Is there a plan for agitation management?
      • Is pain adequately controlled without inducing somnolence or apnea?
  • Face/Neck:
    • Any facial trauma?
      • Tongue or lip swelling?
        • Note:
          • This may be seen in a patient who was previously proned
    • Was the patient a difficult intubation?
      • Note:
        • Does not preclude extubation, but all clinicians should be aware
    • Does the patient have a cuff leak?
  • Chest:
    • Does the patient have any chest trauma/other pathology (eg, rib fractures, etc) that may preclude adequate breathing?
  • Abdomen:
    • Any planned procedures or diagnostics that should happen before extubation?
    • What is the nutrition plan after extubation?
    • Should an NG tube be placed for tube feeds before extubation?
      • Note:
        • Most patients with prolonged intubations have oropharyngeal muscle weakness for days after extubation, precluding normal feeding
  • If there are no barriers to extubation, the patient may be extubated:
    • In preparation, gather supplies that would be needed for oxygenation post-extubation (nasal cannula, oxygen mask, CPAP or BPAP, etc.), as well as supplies that would be needed to intubate the patient again if extubation fails:
      • Endotrachial tubes (ETTs) of appropriate sizes
      • Bag mask with positive end expiratory-pressure (PEEP) valve
      • Airway bougies
      • Tube exchangers
      • Traditional direct laryngoscope
      • Video laryngoscope
      • Flexible bronchoscope
      • Drugs needed for induction
      • Suction catheter
  • For extubation:
    • Put the patient in an upright, seated position
    • Suction the ETT and oral cavity
    • Remove all secretions above the ETT cuff using subglottic suction, if available, or insert a small bore catheter on the side of the ETT for removal of secretions above the ETT cuff
    • Remove the ETT from the holder
    • Ask the patient to take a deep breath and exhale
    • During exhalation, deflate the cuff and smoothly remove the ETT
      • Note:
        • If an orogastric tube is present, it will be removed alongside the ETT and may need to be replaced by a nasogastric tube, if the patient is not ready for oral intake of medications and nutrition
    • Suction the oral cavity
    • Ask the patient to take a deep breath and cough out all secretions
    • Provide supplemental oxygen through a nasal cannula, oxygen mask, etc., as appropriate
    • After extubation, it is important to monitor the patient carefully:
      • Make sure they have adequate oxygenation and provide supplemental oxygen as appropriate
      • If necessary, consider CPAP/BPAP if a patient requires additional support
      • Use bronchodilators as needed, provide secretion management, maintain airway hydration and patent central airway, and encourage patient behaviors that reduce the potential for re-intubation:
        • Coughing
        • Deep breathing
        • Sitting up
        • Moving around if appropriate
  • Risk factors that suggest a patient will need to be re-intubated include:
    • Pneumonia
    • Weak cough
    • Frequent suctioning
    • Rapid shallow breathing index > 58 breaths per minute per liter
    • Positive fluid balance in the 24 hours prior to extubation

Extubation process and post-extubation recommendations modified from Saeed F, Lasrado S. Extubation. [Updated 2019 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539804/

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