LAUSR

Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Fonden In critically ill patients with cardiogenic shock, neurohormonal activation is higher in females compared with males. Whether this is the case in patients resuscitated from out of hospital cardiac arrest (OHCA) is not known and whether sex-based differences relate to achieving mean-arterial-pressure (MAP)-target has not previously been described. This was an investigator-initiated, randomized, controlled study of targeted MAP (63 vs 77 mmHg) and PaO2 (9-10 vs 13-14 kPa) interventions in 789 comatose OHCA (of presumed cardiac origin) patients. Patients underwent serial hemodynamic assessments with pulmonary artery catheter at time of insertion, 6 h, 12 h, 24 h, 36 h and 48 h. Among parameters recorded were heart rate (HR), cardiac output (CO) and central venous pressure (CVP), from which cardiac index (CI) and systemic vascular resistance index (SVRI) were derived. Patient characteristics included sex for stratification, age, time to return of spontaneous circulation (ROSC) and initial electrocardiographic (ECG) rhythm. Hemodynamic parameters from 729 patients were analysed, of which 138 (19%) were female and 591 (81%) were male. Both groups had a median age of 64 years, with median time-to-ROSC of 19 minutes in females versus 18 minutes in males. In females versus in males, SVRI and HR were higher (fig.1,2). There were no differences among sexes with regards to CI, MAP, or dose of noradrenaline. At 12 hours, median SVRI in females was 755 dyn·s/cm5·m2 (inter-quartile ratio, IQR 569-931) versus 554 dyn·s/cm5·m2 (IQR 441-684) in males (P<0.0001). At the same point in time, median HR was 71 beats/minute (bpm) in females (IQR 59-82) versus 62 bpm (IQR 54-74) in males (P<0.0001). Lastly, 12-hour median CI was 1.82 L/min/m2 (IQR 1.54-2.40) in females versus 1.95 L/min/m2 (IQR 1.63-2.43) in males (P=0.1303). Female comatose OHCA patients had higher SVRI and HR during the first 48 hours of ICU admission, without difference in MAP or vasopressor requirement. Sex specific physiological mechanisms may be involved in maintaining vascular resistance.