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Ventilator Emergencies

Acute Desaturation

High Peak Airway Pressure

Low Minute Volume

Circuit Disconnect

High Minute Volume

Acute Desaturation

  • Don PPE

    • DO NOT RUSH - Ensure PPE is donned correctly!​

    • D for Danger comes before ABC​

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  • Optimise oxygenation

    • Boost FiO2 to 100%​

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  • Confirm tube placement and patency

    • Assess for chest rise and fall

    • Check capnograph trace 

      • Confirms correct tube placement

    • Check tube position

      • Has it moved?​

    • Suction endotracheal tube

      • Confirms ETT patency

      • May clear sputum/secretion obstruction

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  • Exclude ventilator cause

    • Check tidal volumes

      • Volume control mode:​

        • Ensure tidal volume delivered matches pre-set tidal volume​

        • Inadequate delivery suggests leak or pressure limiting

          • Ventilator will cease breath delivery if it reaches a pressure limit​

          • Check pressure limit (is it set too low? Should be > 35 cmH2O)

          • If pressure limiting; switch to HIGH PEAK PRESSURE ALGORITHM

      • Pressure control mode:

        • Assess delivered tidal volumes​

        • Worsening lung compliance or airway resistance will result in fall in tidal volume for a given pre-set pressure

    • If in doubt about ventilator functioning, disconnect and manually bag patient

      • Ensure 100% oxygen supply and PEEP valve attached​

      • DO NOT DISCONNECT VENTILATOR OR TRIAL BAG VENTILATION IN A COVID-19 PATIENT

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  • Assess Patient:

    • Auscultate for air entry bilaterally, added sounds, focal changes

    • Send ABG to confirm non-invasive oxygen saturation

    • Observe capnograph trace

      • Waveform trace may suggest aetiology; Eg. airway obstruction, spontaneous breathing, etc.​

    • Urgent CXR

      • Pulmonary oedema, Pneumothorax, focal collapse/consolidation, ETT position​

      • Bedside lung ultrasound may also rapidly identify certain pathology

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  • Call for help early!

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  • Other Management options to consider:

    • Increase sedation/paralysis​

      • Ventilator dysynchrony​

      • Patient biting on ETT

      • Improve chest wall compliance

      • Reduce total metabolic requirements

    • Insertion of bite block

    • Re-positioning

      • Patient will oxygenate better with good lung down (if unilateral pathology)

        • Due to increased perfusion (due to gravity) of lower lung leading to improved V/Q matching

    • Increase mean airway pressure

      • Increase PEEP​

      • Increase inspiratory time

    • Treatment of underlying cause

      • Diuresis

      • Bronchodilators, steroids​​

      • Intercostal catheter insertion

      • Antibiotics

    • Advanced management options

      • Proning​

      • Bronchoscopy

      • Prostacyclin

Acute Desaturation

High Peak Airway Pressures (> 35 cmH2O)

  • Don PPE

    • DO NOT RUSH - Ensure PPE is donned correctly!​

    • D for Danger comes before ABC​

​

  • Call for help early!

​

  • Optimise oxygenation

    • Boost FiO2 to 100%​

​

  • Confirm tube placement and patency

    • Check capnograph trace (if utilised) - confirms correct tube placement

    • Check tube position

      • Has ETT migrated further in?​

    • Suction endotracheal tube

      • Confirms ETT patency

      • May clear sputum/secretion obstruction

​

  • Reduce tidal volume to minimum (4 - 8 ml/kg IBW)

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  • Increase Sedation and consider paralysis

    • Bolus sedation (eg. 20mg propofol, 1-3x)​

    • Paralysis: rocuronium or vecuronium or cisatracurium

      • Requires deep sedation​

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  • Perform plateau pressure measurement

    • Airway pressure following > 1 second inspiratory hold manouvre​

    • Represents alveolar pressure during no-flow state rather than pressure generated by flow against bronchiole airway resistance​

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Plateau Pressure > 30 cmH2O (or unable to complete inspiratory hold)

  • If concurrent significant haemodynamic instability; immediately disconnect patient from ventilator

    • DO NOT DISCONNECT A SUSPECTED OR CONFIRMED COVID-19 PATIENT 

      • In that case, place ventilator in standby mode for 30 seconds

      • Alternatively, reduce respiratory rate to 6 breaths per minute

  • Prolong Expiration - Reduce respiratory rate / prolong I:E ratio (> 1:3)

    • Elevated pressure may be due to breath stacking/dynamic hyperinflation​

      • Occurs where inspiration begins before patient has fully eliminated breath (expiration is a passive process)​​

        • Gas accumulates within lungs

      • May occur if expiratory time too short (eg. Inappropriately high respiratory rate set, tachypnoea) or in airways obstruction

      • Give bronchodilators for bronchospasm

  • Reduce tidal volumes

    • In a patient with significantly reduced lung compliance (eg. ARDS), low tidal volumes may be tolerated, assuming adequate oxygenation can be achieved​​​

  • Investigate and treat other causes:

    • CXR and/or lung US (if competent)​

    • Exclude:

      • Pneumothorax​

      • Endobronchial intubation

        • Usually R main bronchus​

      • Lobar collapse

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Plateau Pressure < 30 cmH2O​

  • Check for circuit obstruction

  • Check for tube-biting or patient-ventilator dysynchrony

    • Treat with sedation boluses and/or increase sedation rate​

      • Eg. 20mg propofol bolus, may be repeated up to 3 times​

  • Assess for evidence of bronchospasm

    • Wheeze, saw-tooth capnograph trace​

    • Treat with bronchodilators +/- corticosteroids

    • Reduce respiratory rate

      • Especially if any evidence of inadequate expiratory time/development of dynamic hyperinflation

  • In bronchospastic patients, high peak airway pressures may be tolerated if plateau pressures remain < 30 cmH2O

    • Requires frequent monitoring of plateau pressures

    • High pressures should only be tolerated if DISCUSSED WITH ICU CONSULTANT!

High Peak Airway Pressures

Low Minute Volume

  • Don PPE

    • DO NOT RUSH - Ensure PPE is donned correctly!​

    • D for Danger comes before ABC​

​

  • If associated with acute desaturation:

    • Follow acute desaturation algorithm​​

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  • If mandatory ventilation:

    • In volume control mode, high peak airway pressures may cause ventilator to pressure limit and dump the breath

      • Follow the high peak airway pressure algorithm​

    • In pressure control mode, falling respiratory system compliance will result in a falling tidal volume for a given pressure delivered

      • Increase pressure control (within appropriate limits - ie. total pressure < 30 cmH2O) 

      • Discuss early with ICU registrar/consultant​

  • If spontaneously ventilating

    • Check tidal volumes​

      • If low, may require increased pressure support (pressure above PEEP that assists during inspiration)​

    • Check respiratory rate

      • If bradypnoeic, switch to SIMV (mandatoy mode) and assess sedation requirements

        • May require more sedation to tolerate mandatory mode

        • May require less sedation to improve spontaneous ventilation

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Low Minute Volume

Circuit Disconnect

  • Don PPE

    • DO NOT RUSH - Ensure PPE is donned correctly!​

    • D for Danger comes before ABC​

    • In suspected or confirmed COVID-19 patients, N-95 masks AND eye protection are required since mechanical ventilation is an aerosolising mechanism

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  • Replace connection if easily identifiable​

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  • In COVID 19 patients, if disconnection not easily identifiable; whilst assessing for circuit disconnect:

    • Clamp endotracheal tube​

    • Place ventilator in standby mode

    • Before recommencing ventilation, check circuit from patient to ventilator to ensure nil disconnections

Circut Disconnect

High Minute Volume / High Respiratory Rate

  • Don PPE

    • DO NOT RUSH - Ensure PPE is donned correctly!​

    • D for Danger comes before ABC

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  • Obtain ABG​​

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  • Metabolic or Respiratory Acidosis

    • Elevated minute ventilation is an appropriate physiologically response to acidosis

    • Confirm ventilatory plan with ICU registrar/consultant 

      • Spontaneous tachypnoea is usually undesirable in a mechanically ventilated patient​

    • Consider increasing mandatory respiratory rate in patients with large tidal volumes

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  • Metabolic or Respiratory Alkalosis

    • Elevated minute ventilation is inappropriate in this setting

    • Consider aetiology:

      • Fever​

      • Pain

      • Brain injury / neurological impairment

      • Respiratory pathology

      • Mixed acid-base disorder

    • These patients likely require increased sedation +/- paralysis​​

High Minute Volume

       Author: Dr. Ryan Slack, Peer Reviewer: Dr. James Douglas / Dr Irma Bilgrami Date: 06/04/20

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