Ten rules for optimizing ventilatory settings and targets in post-cardiac arrest patients

Abstract

Cardiac arrest (CA) is a major cause of morbidity and mortality frequently associated with neurological and systemic involvement. Supportive therapeutic strategies such as mechanical ventilation, hemodynamic settings, and temperature management have been implemented in the last decade in post-CA patients, aiming at protecting both the brain and the lungs and preventing systemic complications. A lung-protective ventilator strategy is currently the standard of care among critically ill patients since it demonstrated beneficial effects on mortality, ventilator-free days, and other clinical outcomes. The role of protective and personalized mechanical ventilation setting in patients without acute respiratory distress syndrome and after CA is becoming more evident. The individual effect of different parameters of lung-protective ventilation, including mechanical power as well as the optimal oxygen and carbon dioxide targets, on clinical outcomes is a matter of debate in post-CA patients. The management of hemodynamics and temperature in post-CA patients represents critical steps for obtaining clinical improvement. The aim of this review is to summarize and discuss current evidence on how to optimize mechanical ventilation in post-CA patients. We will provide ten tips and key insights to apply a lung-protective ventilator strategy in post-CA patients, considering the interplay between the lungs and other systems and organs, including the brain.

Keywords: Brain injury; Cardiac arrest; Lung-protective ventilation; Mechanical power; Mechanical ventilation.

Fig. 1

Variation of tidal volume in function of variation of driving pressure. In this figure, we reported variation of ΔV_T in function of the variation of ΔP (ΔΔP) at different static compliances of the respiratory system (20, 30, 40, 50, 60 mL/cmH₂O). The respiratory rate varies according to the formula of Costa et al. Basal V_T is assumed to be 7 ml/kg of predicted body weight (70 kg)

Fig. 2

Variation of minute ventilation in function of variation of driving pressure. In this figure, the minute ventilation (V_E) varies in function of the variation of driving pressure ΔP (ΔΔP) with (1) fixed respiratory rate to 10 breaths/min on the left, and (2) variable respiratory rate according to the formula by Costa et al. on the right. Basal V_E is assumed to be 7 ml/kg of predicted body weight (70 kg) multiplied by 10 breaths/minute = 4.9 L/min

Fig. 3

Variation of mechanical power in function of variation of driving pressure. In this figure, the variation of mechanical power (ΔMP) in J/min changes in function of the variation of driving pressure ΔP (ΔΔP) with (1) fixed respiratory rate to 10 breaths/min on the left, and (2) variable respiratory rate according to the formula by Costa et al. on the right. The figure depicts the variation at different compliances of the respiratory system (20, 30, 40, 50, 60 mL/cmH₂O). Basal MP is assumed to be calculated on a tidal volume (V_T) of 7 ml/kg of predicted body weight (70 kg) and PEEP = 0 cmH₂O, according to the formula of MP in pressure control ventilation = 0.098 × respiratory rate × V_T × (PEEP + ΔP)

Fig. 4

Ten key rules for optimizing ventilator setting in post-CA patients according to an organ protective mechanical ventilation strategy. V_T = tidal volume, PBW = predicted body weight, PEEP = positive end-expiratory pressure, RR = respiratory rate, ΔP = driving pressure, MP = mechanical power, PaO₂ = arterial partial pressure of oxygen, PaCO₂ = arterial partial pressure of carbon dioxide, TTM = target temperature management, MAP = mean arterial pressure, CA, cardiac arrest