Hemodynamic Effects of a High-Frequency Oscillatory Ventilation Open-Lung Strategy in Critically Ill Children With Acquired or Congenital Cardiac Disease

Abstract

Objectives: To study the hemodynamic consequences of an open-lung high-frequency oscillatory ventilation (HFOV) strategy in patients with an underlying cardiac anomaly with or without intracardiac shunt or primary pulmonary hypertension with severe lung injury.

Design: Secondary analysis of prospectively collected data.

Setting: Medical-surgical PICU.

Patients: Children less than 18 years old with cardiac anomalies (± intracardiac shunt) or primary pulmonary hypertension.

Interventions: None.

Measurements and main results: Data from 52 subjects were analyzed, of whom 39 of 52 with cardiac anomaly (23/39 with intracardiac shunt) and 13 of 52 with primary pulmonary hypertension. Fourteen patients were admitted postoperatively, and 26 patients were admitted with acute respiratory failure. Five subjects (9.6%) were canulated for ECMO (of whom four for worsening respiratory status). Ten patients (19.2%) died during PICU stay. Median conventional mechanical ventilation settings prior to HFOV were peak inspiratory pressure 30 cm H 2 O (27-33 cm H 2 O), positive end-expiratory pressure 8 cm H 2 O (6-10 cm H 2 O), and F io2 0.72 (0.56-0.94). After transitioning to HFOV, there was no negative effect on mean arterial blood pressure, central venous pressure, or arterial lactate. Heart rate decreased significantly over time ( p < 0.0001), without group differences. The percentage of subjects receiving a fluid bolus decreased over time ( p = 0.003), especially in those with primary pulmonary hypertension ( p = 0.0155) and without intracardiac shunt ( p = 0.0328). There were no significant differences in the cumulative number of daily boluses over time. Vasoactive Infusion Score did not increase over time. Pa co2 decreased ( p < 0.0002) and arterial pH significantly improved ( p < 0.0001) over time in the whole cohort. Neuromuscular blocking agents were used in all subjects switched to HFOV. Daily cumulative sedative doses were unchanged, and no clinically apparent barotrauma was found.

Conclusions: No negative hemodynamic consequences occurred with an individualized, physiology-based open-lung HFOV approach in patients with cardiac anomalies or primary pulmonary hypertension suffering from severe lung injury.

Figure 1.

Level and time course of hemodynamic variables including heart rate (A), mean arterial blood pressure (B), central venous pressure (C), and blood lactate (D) during the last 6 hr of conventional mechanical ventilation and the subsequent first 72 hr of high-frequency oscillatory ventilation, stratified by underlying diagnosis (with intracardiac shunt [n = 23], without intracardiac shunt [n = 16], and with primary pulmonary hypertension [n = 13]). “Start” is the first measurement immediately after the recruitment maneuver. Data are depicted as median (25–75 interquartile range). *p < 0.05. CMV = conventional mechanical ventilation, HFOV = high-frequency oscillatory ventilation.

Figure 2.

Level and time course of the percentage of patients who received fluid boluses per day (A) and the cumulative amount of fluid boluses in mL/kg (B), patients on vasoactive support per day (C) and vasoactive score (D) stratified by underlying diagnosis (with intracardiac shunt [n = 23], without intracardiac shunt [n = 16], and with primary pulmonary hypertension [n = 13]). Continuous data are depicted as median (25–75 interquartile range), and categorical data as percent of total. CMV = conventional mechanical ventilation. *p < 0.05.

Figure 3.

Percentage of patients who were on neuromuscular blocking agents (A), mean equipotent dosage of lorazepam (B), and mean equipotent dosage of methadone dosage (C) stratified by underlying diagnosis (with intracardiac shunt [n = 23], without intracardiac shunt [n = 16], and with primary pulmonary hypertension [n = 13]). Continuous data are depicted as median (25–75 interquartile range) and categorical data as percent of total. CMV = conventional mechanical ventilation. *p < 0.05.