The Value of Combining Carbon Dioxide Gap and Oxygen-Derived Variables with Lactate Clearance in Predicting Mortality after Resuscitation of Septic Shock Patients

Background. Achieving hemodynamic stabilization does not prevent progressive tissue hypoperfusion and organ dysfunction during resuscitation of septic shock patients. Many indicators have been proposed to judge the optimization of oxygen delivery to meet tissue oxygen consumption. Methods. A prospective observational study was conducted to evaluate and validate combining CO2 gap and oxygen-derived variables with lactate clearance during early hours of resuscitation of adults presenting with septic shock. Results. Our study included 456 adults with a mean age of 63.2 ± 6.9 years, with 71.9% being males. Respiratory and urinary infections were the origin of about 75% of sepsis. Mortality occurred in 164 (35.9%) patients. The APACHE II score was 18.2 ± 3.7 versus 34.3 ± 6.8 ( p < 0.001 ), the initial SOFA score was 5.8 ± 3.1 versus 7.3 ± 1.4 ( p = 0.001 ), while the SOFA score after 48 hours was 4.2 ± 1.8 versus 9.4 ± 3.1 ( p < 0.001 ) in the survivors and nonsurvivors, respectively. Hospital mortality was independently predicted by hyperlactatemia (OR: 2.47; 95% CI: 1.63–6.82, p = 0.004 ), PvaCO2 gap (OR: 2.62; 95% CI: 1.28–6.74, p = 0.026 ), PvaCO2/CavO2 ratio (OR: 2.16; 95% CI: 1.49–5.74, p = 0.006 ), and increased SOFA score after 48 hours of admission (OR: 1.86; 95% CI: 1.36–8.13, p = 0.02 ). A blood lactate cutoff of 40 mg/dl at the 6th hour of resuscitation (T6) had a 92.7% sensitivity and 75.3% specificity for predicting hospital mortality (AUROC = 0.902) with 81.6% accuracy. Combining the lactate cutoff of 40 mg/dl and PvaCO2/CavO2 ratio cutoff of 1.4 increased the specificity to 93.2% with a sensitivity of 75.6% in predicting mortality and with 86.8% accuracy. Combining the lactate cutoff of 40 mg/dl and PvaCO2 gap of 6 mmHg increased the sensitivity to 93% and increased the specificity to 98% in predicting mortality with 91% accuracy. Conclusion. Combining the carbon dioxide gap and arteriovenous oxygen difference with lactate clearance during early hours of resuscitation of septic shock patients helps to predict hospital mortality more accurately.

Cardiac and skeletal muscle predictors of impaired cardiorespiratory fitness post-anthracycline chemotherapy for breast cancer

This study aimed to characterize peak exercise cardiac function and thigh muscle fatty infiltration and their relationships with VO2peak among anthracycline-treated breast cancer survivors (BCS). BCS who received anthracycline chemotherapy ~ 1 year earlier (n = 16) and matched controls (matched-CON, n = 16) were enrolled. Resting and peak exercise cardiac function, myocardial T1 mapping (marker of fibrosis), and thigh muscle fat infiltration were assessed by magnetic resonance imaging, and VO2peak by cycle test. Compared to matched-CON, BCS had lower peak SV (64 ± 9 vs 57 ± 10 mL/m2, p = 0.038), GLS (− 30.4 ± 2.2 vs − 28.0 ± 2.5%, p = 0.008), and arteriovenous oxygen difference (16.4 ± 3.6 vs 15.2 ± 3.9 mL/100 mL, p = 0.054). Mediation analysis showed: (1) greater myocardial T1 time (fibrosis) is inversely related to cardiac output and end-systolic volume exercise reserve; (2) greater thigh muscle fatty infiltration is inversely related to arteriovenous oxygen difference; both of which negatively influence VO2peak. Peak SV (R2 = 65%) and thigh muscle fat fraction (R2 = 68%) were similarly strong independent predictors of VO2peak in BCS and matched-CON combined. Post-anthracyclines, myocardial fibrosis is associated with impaired cardiac reserve, and thigh muscle fatty infiltration is associated with impaired oxygen extraction, which both contribute to VO2peak.

Effect of supplemental dexmedetomidine in interventional embolism on cerebral oxygen metabolism in patients with intracranial aneurysms

Objective To investigate the effect of supplemental dexmedetomidine in interventional embolism on cerebral oxygen metabolism in patients with intracranial aneurysms. Methods Ninety patients who underwent interventional embolism of intracranial aneurysms were equally divided into Group A and Group B. In Group A, dexmedetomidine was injected intravenously 10 minutes before inducing anesthesia, with a loading dose of 0.6 µg/kg followed by 0.4 µg/kg/hour. Group B received the same amount of normal saline by the same injection method. Heart rate (HR), mean arterial pressure (MAP), arterial–jugular venous oxygen difference [D(a-jv) (O2)], cerebral oxygen extraction [CE (O2)], and intraoperative propofol use were recorded before inducing anesthesia (T0) and at five time points thereafter. Results The amount of propofol in Group A was lower vs Group B. At all five time points after T0, HR, MAP, D(a-jv) (O2), and CE (O2) in Group A were significantly lower vs Group B, with significant differences for jugular venous oxygen saturation (SjvO2) and the oxygen content of the internal jugular vein (CjvO2) between the groups. Conclusion Dexmedetomidine resulted in less intraoperative propofol, lower D(a-jv) (O2) and CE (O2), and improved cerebral oxygen metabolism.

Abstract 16032: Determinants of Exercise Capacity Assessed Using Combined Stress Echocardiography and Cardiopulmonary Exercise Testing in Patients Treated for Acute Myocardial Infarction

Introduction: Exercise capacity (EC) after acute myocardial infarction (AMI) influences prognosis, but the causes of its reduction are complex and not sufficiently studied. Methods: We prospectively enrolled consecutive patients who underwent percutaneous coronary intervention for their first AMI without residual coronary stenosis and with left ventricular ejection fraction (LVEF) > 40% more than 4 weeks after the AMI. We performed combined stress echocardiography and cardiopulmonary exercise testing (CPET-SE) using a semi-supine cycle ergometer to determine predictors of EC (peak oxygen uptake [VO 2 ]). Results: Among 81 patients (70% male, mean age 58 ± 11 years), 40% suffered AMI with ST-segment elevation (STEMI), and 60% non-STEMI, LVEF was 57 ± 7%; wall motion score index, 1.18 (IQR 1.06 - 1.31); peak VO 2 , 19.5 ± 5.4 mL/kg/min. Multivariate analysis ( Table ) revealed that parameters at peak exercise: heart rate (β = 0.17, p < 0.001), stroke volume (β = 0.09, p < 0.001), and arteriovenous oxygen difference (β = 93.51, p < 0.001) were independently positively correlated with peak VO 2 , with arteriovenous oxygen difference being its strongest contributor. At rest, left ventricular systolic and diastolic function parameters and the extent of myocardial scarring (wall motion score index) did not predict EC (p > 0.05). Conclusions: In patients treated for AMI with normal/mildly reduced LVEF, EC is associated with peak peripheral oxygen extraction as well as peak heart rate and peak stroke volume. CPET-SE is a useful tool to evaluate decreased fitness in this group.

Whole Body Fat Free Mass and Vo2peak in Recreationally Active Men and Women

BACKGROUND: Vo2peak has traditionally been thought to be regulated by cardiac output and arteriovenous-oxygen difference. A “muscle-centric” view suggests the cardiovascular system is secondarily responsive to the primary driver: active muscle mass.METHODS: A total of 19 recreationally active men (N = 10) and women (N = 9) performed a Vo2peak test, a Vo2peak verification test on an electrically braked cycle ergometer on the same day, and a hydrostatic weighing test to assess fat free mass after providing written informed consent.RESULTS: Vo2peak was significantly higher in men (3.74 ± 0.6 L · min−1) than women (2.22 ± 0.30 L · min−1). Whole body fat free mass explained 91% of the variability in Vo2peak (R2 = 0.91) in the men and women combined, 81% of the variability in Vo2peak in men alone, and 46% of the variability in Vo2peak in women alone. None of these subjects were highly trained.DISCUSSION: Fat free mass, a surrogate for muscle mass, was the primary predictor of Vo2peak in this group of recreationally active men and women. Therefore, it appears that whole body fat free mass (a surrogate for muscle mass) is the primary driver for Vo2peak in these recreationally active men and women. These data have implications as to the type of training NASA personnel should be undertaking: resistance training as opposed to aerobic training.Lambert CP. Whole body fat free mass and Vo2peak in recreationally active men and women. Aerosp Med Hum Perform. 2020; 91(2):102–105.

Severe hypoxia caused by ascending aorta elongation due to aortic arch aneurysm

Patent foramen ovale, sometimes associated with clinical manifestation, is frequently detected during adulthood. Platypnea-orthodeoxia syndrome, a rare condition characterized by dyspnea and hypoxia aggravated in the upright position, is caused by a right-to-left shunt across a patent foramen ovale. We present a case of a 73-year-old man with severe hypoxia caused by an aortic arch aneurysm that distorted the atrial septal geometry and worsened the right-to-left shunt. Clinicians should consider a right-to-left shunt via a patent foramen ovale when an aortic arch aneurysm causes counterclockwise cardiac rotation. Furthermore, the alveolar-arterial oxygen difference can be used to diagnose platypnea-orthodeoxia syndrome.