Introduction: Cardiovascular instability in inhalation injury is two-fold. First, pronounced pro-inflammatory state with higher intravascular volume needs and risks of controlled ventilation. Second, airway narrowing, patient-ventilator dys-synchrony, elevated intrathoracic pressures and alveolar hyperinflation decrease right and left heart preload consequent to auto-PEEP. Hypotension in phase with ventilation may indicate auto-PEEP. High index of suspicion for auto-PEEP as a proximate cause of cardiovascular instability is appropriate to prevent harm in this vulnerable population.
Description: A 39-year-old male experienced superficial burn (less than 3% TBSA) consequent to a house fire. Grade-3 inhalation injury was identified and he was intubated for controlled ventilation. Central venous and arterial catheterization was initiated for vascular access and intra-arterial monitoring. Large volumes of crystalloid were administered for hypotension consequent to insensible losses and vasoplegia concurrent with pro-inflammatory state. Agitation/ventilator dys-synchrony was treated with midazolam/fentanyl followed by cis-atracurium. Hemodynamic indices were derived from the intra-arterial waveform. Hypotension and decreased cardiac output/cardiac index and stroke volume occurred in peak inspiration. Pro-inflammatory state normally causes supra-normal cardiac indices. Evaluating patient-ventilator interface and ventilator graphics identified auto-PEEP (7-10 cm H2O), resolved by titrating ventilator flow rates and mitigating patient-ventilator dys-synchrony. Blood pressure and hemodynamic indices recovered to patient-specific baselines. Ventilator support and mechanism-based care for inhalation injury was titrated downward with final liberation from ventilator support and discharge.
Discussion: Inhalation injury with airway edema, hypoxemia/hypercarbia and pro-inflammatory state risks patient-ventilator dys-synchrony, auto-PEEP and hypotension. Early recognition of patient-ventilator dys-synchrony and auto-PEEP identifies causes of cardiovascular instability and treatment opportunities. This case illustrates interdisciplinary care and leveraging ventilator graphics analysis with real-time hemodynamic indices facilitating rapid identification and management of unstable cardiac state due to auto-PEEP.
