Acute Asthma Exacerbation Clinical Pathway – PICU – Mechanical Ventilation

Acute Asthma Exacerbation Clinical Pathway – PICU

Mechanical Ventilation

Components of Care Considerations
Consider Mechanical Ventilation

Requires intubation with induction/sedation for endotracheal tube placement

  • Changes in Physiology
    • Passive exhalation
    • Less negative intrapleural pressures = more airway collapse
    • Requires additional intrathoracic pressure
  • Associated with increased risk of
    • Air leak syndrome (pneumothorax)
    • Cardiac arrest (decreased preload with significant respiratory acidosis)
Ventilator Diagnostics
  • Maneuvers to Aid in the Assessment
    • Intrinsic PEEP: A measure of the degree of “air trapping”
    • Plateau pressure (PPLAT): A measure of the pressure applied to small airways and alveoli
    • Comparing the PPLAT to the peak inspiratory pressure can yield important information in determining the presence of
      airway resistance vs. poor compliance
    • A large gradient between the two pressures is indicative of primary airway resistance
    • Drager Evita V500 Procedure
Ventilator Strategies
  • Considerations
    • Many asthmatics do not have ARDS, and do not require low tidal volume ventilation
    • Large tidal volume, low respiratory rate ventilation minimizes dead space fraction
    • Above-mentioned diagnostics help choose initial ventilator settings
    • Diagnostics are available on the on ICU ventilator, limitations exist in anesthesia machines
Strategies of Invasive Mechanical Ventilation
Controlled Ventilation
  • May be indicated if:
    • PPLAT > 30 cm H2O
    • Ventilator dyssynchrony
    • Significant hypoxemia
Spontaneous Breathing
  • Adequate oxygenation
  • Pressure support (PS) ventilation with PEEP allows child to dictate an I:E ratio that is potentially more synchronous
  • Intrinsic PEEP may be beneficial in the selection of PEEP when unable to trigger
    the ventilator
  • May also stent open small airways
Bronchodilation Therapies
Analgesia and Anxiolysis
  • Refer to PICU Sedation Pathway
  • There is no evidence that ketamine provides bronchodilation in any mechanism other than endogenous
    catecholamine release
  • If using isoflurane, consider stopping other analgesic and anxiolytic medications
    • When weaning isoflurane, restart or increase these infusions
Neuromuscular Blockade
  • Under most circumstances, a neuromuscular blocking agent is required for the placement of endotracheal tube.
    This precludes spontaneous breathing.
  • If on controlled ventilation, an infusion of nondepolarizing muscle relaxant can aid in oxygenation and
    pulmonary compliance.
ECMO Consult
  • Consult ECMO team for all intubated children with status asthmaticus
  • Consider initiation for ECMO in the setting of
    • Air leak syndrome (pneumothorax, pneumomediastinum)
    • PPLAT greater than 30 cm H2O
    • Refractory hypoxemia and/or significant acidosis
  • ECMO Activation and Initiation Job Aid
Consider Isoflurane
  • Discontinue all other inhaled therapies at the time of isoflurane initiation
  • Consider reinitiation of inhaled therapies when weaning isoflurane
Requirements
  • Anesthesia machine
  • Anesthesia consultation
  • Considerations of significant vasodilation
Population Persistent poor air entry despite maximum medical therapy and optimal mechanical ventilation support
Timing of Initiation Intubated with persistent wheeze despite maximally tolerated albuterol
Dosing Age dependent; discuss with anesthesia
Monitoring
  • Blood q2–4hr
  • BMP, Mg, Phos q6–12hr
De-escalation
Once Extubated
  • Typically, most children qualify for complete cessation of all analgesic and anxiolytic infusions
  • Follow Critical severity guidance