[abstract] ASSESSMENT OF ARTERIAL BLOOD GASES AFTER HBO2T: AN OBSERVATIONAL PROSPECTIVE STUDY IN CRITICALLY ILL PATIENTS

Abstract

BACKGROUND: HBO2therapy has previously been linked with the need of an increased inspiratory fraction of oxygen (FIO2) after exposure (Weaver et al. Chest 1994;106:1134-39. Keenan et al.J Crit Care 1998;13(1):7-12).. The purpose of the current investigation was to evaluate the alteration of arterial blood gas (ABG) values in mechanically ventilated intensive-care patients following HBO2T. METHODS: After approval of the study protocol by the local Ethics Committee and obtainment of informed consent, 8 subjects (7m, 1f, 44-70 yr) undergoing HBO2T were enrolled in the study (diagnoses: necrotizing soft tissue infection: 4 pts., burn injury: 2 pts., major abdominal surgery: 2 pts.). All patients were sedated and mechanically ventilated. ABGs were closely monitored in the ICU before, during and 1,2,3,6 hr after HBO2T and after both transports (Table 1). ICU ventilator settings (Evita 4, Drager Corp., Germany) and FIO2 (0.34-0.55) remained unchanged. Transport and chamber ventilator settings were adjusted according to baseline ventilation pattern and airway pressures. Variables of ventilation and vital parameters were recorded. HBO2protocol: 2.35 + 0.15 ATA, isopression phase: 50 min., 2nd session (on average). Statistics: Paired Wilcoxon test. RESULTS: PaO2 during HBO2T: 118.3 (85.7/145.3) kPa. Table 1. Median percent changes (min/max) in comparison to baseline values. ABG 1 hr 2 hr 3 hr 6 hr Transport ICU-chamber Transport Chamber-ICU, pH -0.2 percent,(-1/0.8) +0.1percent, (-2/1) +0.2percent, (-2/1) +0.1percent, (-2/1) +0.1percent, (-2/1) +0.5percent, (-2/1), Oxygen tension (PaO2) -30.2percent, (-36/-4), (P=0.018) -8.8percent, (-32/14),+9.6percent, (-12/28) -2.2percent, (-26/41) +56.0percent, (5/165) +46.9percent (-25/203), CO2-tension (PaCO2) +8.3percent, (-11/17) +2.5percent, (-22/27) -2.2percent, (-13/30) -0.8percent,(-39/34) +2.1percent, (-15/37) -7.2percent(-21/64), Saturation (SaO2) -1.9percent(-8/0), (P=0.028) -0.4percent, (-8/0) +0.2percent, (-1/2) +0.0percent, (-4/2) +0.9percent, (0/2) +1.1percent(-12/207), CONCLUSION: The decrease of PaO2 after HBO2T in ventilated critically ill patients was brief and reversible. Further studies on etiology and dose-dependency are required.