Blood gas parameters during cardio-pulmonary resuscitation in a post hoc analysis-porcine study with data pooled from two studies: increased acidosis with repeated adrenaline injections compared to a control group during prolonged advanced life support.

BACKGROUND: Cardiopulmonary resuscitation (CPR) guidelines recommend an injection of 1 mg of adrenaline every 3-5 min in a cardiac arrest situation. Adrenaline increases return of spontaneous circulation (ROSC) and induces a more acidotic state in cardiac arrest situations. Blood gas analysis is a useful tool to assess the metabolic state during CPR.Most experimental studies have been conducted with a single injection of adrenaline. However, little is known about how blood gas parameters are affected by repeated adrenaline injections during prolonged CPR. METHODS: This was a pooled post-hoc analysis from two studies, in which repeated injections of adrenaline and saline as a control were administered during 16- or 21-min of CPR according to current guidelines. Sixty pigs were induced with cardiac arrest, randomised to either adrenaline or saline. Arterial blood gases were drawn at baseline, after the second and fourth injection of adrenaline/saline, and after 5 and 10 min of ROSC. The analysis included pH, Base excess, Bicarbonate, lactate, partial pressure of carbon dioxide, partial pressure of oxygen, oxygen saturation, haemoglobin, and potassium. RESULTS: Sixteen/twenty-four animals (66.7%) obtained ROSC in the control group and 17/36(47.2%) in the adrenaline group (ns). Adrenaline resulted in significantly lower pH, base excess, and bicarbonate higher lactate, carbon dioxide, haemoglobin and potassium, compared to a control-group among animals that achieved ROSC, but not in non-ROSC groups. CONCLUSION: Repeated adrenaline injections was associated with a more acidotic profile and higher potassium and haemoglobin levels in animals that achieved ROSC during prolonged CPR compared with the control-group. However, this was not seen in the non-ROSC groups.