Serial assessments of cardiac output and mixed venous oxygen saturation in comatose patients after out-of-hospital cardiac arrest

Abstract

Aim To assess the association with outcomes of cardiac index (CI) and mixed venous oxygen saturation (SvO2) in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA). Methods In the cohort study of 789 patients included in the “BOX”-trial, 565 (77%) patients were included in this hemodynamic substudy (age 62 ± 13 years, male sex 81%). Pulmonary artery catheters were inserted shortly after ICU admission. CI and SvO2 were measured as soon as possible in the ICU and until awakening or death. The endpoints were all-cause mortality at 1 year and renal failure defined as need for renal replacement therapy. Results First measured CI was median 1.7 (1.4–2.1) l/min/m2, and first measured SvO2 was median 67 (61–73) %. CI < median with SvO2 > median was present in 222 (39%), and low SvO2 with CI < median was present in 59 (11%). Spline analysis indicated that SvO2 value < 55% was associated with poor outcome. Low CI at admission was not significantly associated with mortality in multivariable analysis (p = 0.14). SvO2 was significantly inversely associated with mortality (hazard ratioadjusted: 0.91 (0.84–0.98) per 5% increase in SvO2, p = 0.01). SvO2 was significantly inversely associated with renal failure after adjusting for confounders (ORadjusted: 0.73 [0.62–0.86] per 5% increase in SvO2, p = 0.001). The combination of lower CI and lower SvO2 was associated with higher risk of mortality (hazard ratioadjusted: 1.54 (1.06–2.23) and renal failure (ORadjusted: 5.87 [2.34–14.73]. Conclusion First measured SvO2 after resuscitation from OHCA was inversely associated with mortality and renal failure. If SvO2 and CI were below median, the risk of poor outcomes increased significantly. Registration The BOX-trial is registered at clinicaltrials.gov (NCT03141099, date 2017–30–04, retrospectively registered). Graphical abstract

Blood Pressure Target in Out-of-Hospital Cardiac Arrest With Preexisting Heart Failure: (Don’t) Go With the Flow?

“…7 The BOX investigators have demonstrated in another analysis of their trial that the first mixed venous oxygen saturation after resuscitation from OHCA was inversely associated with mortality and renal failure. 8 It is, therefore, somewhat disturbing that the higher MAP target in patients with heart failure was associated with a 2.73 higher odds for the need of renal replacement therapy; yet the current analysis was grossly underpowered to assess this end point. Trends in lactate, urine output, or biomarkers for organ dysfunction offer important complementary information to help interpretation of hemodynamics.…”

Impact of Blood Pressure Targets in Patients With Heart Failure Undergoing Postresuscitation Care: A Subgroup Analysis From a Randomized Controlled Trial

“…In patients with cardiac arrest, the weakened myocardium could be more prone to post-OHCA myocardial dysfunction. CI is not associated with clinical outcomes 30,[33][34][35] ; however, the response of this myocardium to increased afterload and vasopressor stress, indicated by changes in CI with higher vasopressor doses, provides valuable mechanistic insights. Although the sample size is small for conclusive clinical outcomes, this information is hypothesis generating for future hemodynamic studies of effects of MAP and vasopressor manipulation.…”

“…29 A previously investigated interobserver variation demonstrated low bias and high reproducibility. 30 In Odense, continuous cardiac output measurement was obtained through intermittent blood heating, with the response detected by a thermistor located at the catheter's tip. 31 Previous studies have shown excellent correlation, accuracy, and precision among different methods of cardiac output measurement.…”

“…An analysis of the prognostic value of low cardiac index has previously been published from the BOX trial cohort regardless of heart failure status. 30 Transthoracic echocardiography was performed according to the departments standard of care by experienced cardiologists with the patient in supine position tilted 15° toward left to allow for acquisition of apical views. Images were stored for offline analysis using Philips Xcelera analysis software (Philips Healthcare).…”

Lower versus higher blood pressure targets in comatose patients resuscitated from out‐of‐hospital cardiac arrest—Protocol for a secondary Bayesian analysis of the box trial

“…[4][5][6] Pilot studies have suggested that higher mean arterial pressure (MAP) post-OHCA, typically achieved using vasopressors like noradrenaline, may reduce brain injury. [7][8][9][10] However, vasopressors carry risks such as cardiac arrhythmias, myocardial ischemia, and increased afterload, and are associated with adverse outcomes. 11 No firm conclusion on the benefits and harms of a lower vs. a higher blood pressure target has been drawn for patients admitted to the ICU after OHCA.…”