Influence of high altitude after a prior ascent on physical exhaustion during cardiopulmonary resuscitation: a randomised crossover alpine field experiment.

BACKGROUND: Performing cardiopulmonary resuscitation (CPR) inevitably causes significant physical, as well as psychological stress for rescuers. Physical activity at high altitude, a hypobaric and hypoxic environment, similarly adds to the level of stress and causes multiple physiological changes. Continuous measurement of pulse rate serves as an objective measure of fatigue during CPR. We therefore aimed to investigate rescuers' heart rates as a measure of physical strain during CPR in a high-altitude alpine environment to provide a better understanding of the physiological changes under these very special conditions. METHODS: Twenty experienced mountaineers performed basic life support (BLS) on a manikin for 16 min, both at baseline altitude and at high altitude (3454 m) following a quick and exhausting ascent over 1200 m. Sequence of scenarios was randomised for analysis. Heart rate was continuously measured and compared between baseline and high altitude by absolute differences and robust confidence intervals. RESULTS: During CPR at baseline, the average heart rate increased from 87 bpm (SD 16 bpm) to 104 bpm [increase 17 bpm (95% CI 8.24-24.76)], compared to an increase from 119 bpm (SD 12 bpm) to 124 bpm [increase 5 bpm (95% CI - 1.59 to 12.19)] at high altitude [difference between two groups 32 bpm (95% CI 25-39)]. Differences between periods of chest compressions and ventilations were very similar at baseline [19 bpm (95%CI 16.98-20.27)] and at high altitude [20 bpm 95% CI 18.56-21.44)], despite starting from a much higher level at high altitude. The average heart rates of rescuers at high altitude at any point were higher than those at baseline at any other point. CONCLUSION: Performing BLS CPR causes exhaustion both at base level and at a high altitude. A further increase during CPR might imply a physiological reserve for adapting to additional physical exertion at high altitude. Phases of ventilation are much needed recovery-periods, but heart rates remain very high. Subjective measures of exhaustion, such as the BORG-scale, might lead to rescuers' overestimation of their own performance.

Arterial stiffness in acute coronary syndrome as a potential triage tool: a prospective observational study.

BACKGROUND: Diagnosis and percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) are time-sensitive. Triage and algorithms identify patients at high-risk. However, additional prediction tools are warranted for prioritized care based on predicted coronary pathologies and PCI complexity. Pulse-wave velocity (PWV) is a non-invasive measurement related to cardiovascular morbidity, and their exact value in ACS evaluation is unclear. METHODS: In patients undergoing coronary angiography (CA) and - if warranted - PCI for ACS evaluation at a tertiary university hospital in Vienna, Austria, brachial-ankle (ba)PWV and carotid-femoral (cf)PWV were prospectively measured from January 2020 to January 2021. RESULTS: PWV was measured in 58 patients (60.3% male; 65 [61-69] years). Risk prediction scores (GRACE, CRUSADE, TIMI), cardiac enzymes, and fraction of patients with a three-vessel disease were significantly higher in the pathological PWV ranges. Adjusted for age and comorbidities, baPWV independently predicted the LAD being relevantly stenotic (crude OR=1.416 [1.143-1.755], P=0.001; adjusted OR=1.340 [1.039-1.727], P=0.024; cut-off 15.5 m/s in CART-analysis), being the culprit lesion (crude OR=1.320 [1.094-1.594], P=0.004; adjusted OR=1.311 [1.037-1.657], P=0.024; cut-off 15.5 m/s), and being totally occluded (crude OR=1.422 [1.113-1.818], P=0.005; adjusted OR=1.677 [1.189-2.366], P=0.003; cut-off 19.6 m/s). Moreover, CA or PCI complexity were associated with higher PWV. CONCLUSIONS: Pathological PWV as a surrogate for arterial stiffness, polyvascular disease and a larger atherosclerotic burden was associated with GRACE, CRUSADE, and TIMI scores, and PCI duration and complexity. BaPWV independently predicted relevant LAD pathologies, and is suggested as a potential novel triage and prioritization tool for suspected NSTE-ACS in emergency departments.

Impact of more conservative European Society of Cardiology guidelines on the management of patients with acute chest pain.

OBJECTIVE: Early diagnosis or rule-out of acute coronary syndrome (ACS) is a key competence of emergency medicine. Changes in the NSTE-ACS guidelines of the European Society of Cardiology (ESC) in 2015 and 2020 both warranted a henceforth more conservative approach regarding high-sensitivity troponin t (hsTnt) testing. We aimed to assess the impact of more conservative guidelines on the frequency of early rule-out and prolonged observation with repeated hsTnt testing at a high-volume tertiary care emergency department. PATIENTS AND METHODS: We conducted a pre- and post-changeover analysis 3 months before and 3 months after transition from less (hsTnt cut-off 30 ng/L, 3-hour rule-out) to more conservative (hsTnt cut-off 14 ng/L, 1-hour rule-out) guidelines in 2015, comparing proportions of patients requiring repeated testing. RESULTS: We included 5442 cases of symptoms suspicious of acute cardiac origin (3451 before, 1991 after, 2370 (44%) female, age 55 (SD 19) years). The proportion of patients fulfilling early-rule out criteria decreased from 68% (2348 patients) before to 60% (1195 patients) with the 2015 guidelines (P < .01). Those requiring repeated testing significantly (P < .01) increased from 22% (743 patients) to 25% (494 patients). Positive results in repeated testing significantly (P = .02) decreased from 43% (320 patients) to 37% (181 patients). Invasive diagnostics were performed in 91 patients (2.6%) before and in 75 patients (3.8%) after (P = .02) the guideline revision. CONCLUSION: The implementation of the more conservative 2015 ESC guidelines led to a minor rise in prolonged observations because of an increase in negative repeated testing and to an increase in invasive procedures.