Impact of physical fitness and biometric data on the quality of external chest compression: a randomised, crossover trial.

BACKGROUND: During circulatory arrest, effective external chest compression (ECC) is a key element for patient survival. In 2005, international emergency medical organisations changed their recommended compression-ventilation ratio (CVR) from 15:2 to 30:2 to acknowledge the vital importance of ECC. We hypothesised that physical fitness, biometric data and gender can influence the quality of ECC. Furthermore, we aimed to determine objective parameters of physical fitness that can reliably predict the quality of ECC. METHODS: The physical fitness of 30 male and 10 female healthcare professionals was assessed by cycling and rowing ergometry (focussing on lower and upper body, respectively). During ergometry, continuous breath-by-breath ergospirometric measurements and heart rate (HR) were recorded. All participants performed two nine-minute sequences of ECC on a manikin using CVRs of 30:2 and 15:2. We measured the compression and decompression depths, compression rates and assessed the participants' perception of exhaustion and comfort. The median body mass index (BMI; male 25.4 kg/m2 and female 20.4 kg/m2) was used as the threshold for subgroup analyses of participants with higher and lower BMI. RESULTS: HR during rowing ergometry at 75 watts (HR75) correlated best with the quality of ECC (r = -0.57, p < 0.05). Participants with a higher BMI and better physical fitness performed better and showed less fatigue during ECC. These results are valid for the entire cohort, as well as for the gender-based subgroups. The compressions of female participants were too shallow and more rapid (mean compression depth was 32 mm and rate was 117/min with a CVR of 30:2). For participants with a lower BMI and higher HR75, the compression depth decreased over time, beginning after four minutes for the 15:2 CVR and after three minutes for the 30:2 CVR. Although found to be more exhausting, a CVR of 30:2 was rated as being more comfortable. CONCLUSION: The quality of the ECC and fatigue can both be predicted by BMI and physical fitness. An evaluation focussing on the upper body may be a more valid predictor of ECC quality than cycling based tests. Our data strongly support the recommendation to relieve ECC providers after two minutes.

Cardiovascular responses during thermoneutral, head-out water immersion in patients with coronary artery disease.

PURPOSE: Water is frequently recommended as a therapeutic medium for cardiac patients. Reports on the cardiovascular response to immersion often differ, however, depending, for instance, if full or partial immersion were considered. The purpose of this study was to examine the cardiovascular responses to 2 immersion protocols in 3 age and gender-matched groups of patients each with a specific coronary artery disease. METHODS: Fifteen patients with coronary artery disease entered water using a stepwise immersion (STEP) protocol (5 stages in 15 minutes) and an immediate, complete immersion (IM) protocol (2 stages in 6 minutes). Cardiac indices were monitored by transthoracic echocardiography. The heart rate was generated from the electrocardiogram, and blood pressure was measured using a manual mercury manometer. RESULTS: The end-diastolic volume, end-systolic volume, stroke volume, and cardiac output decreased during STEP but increased during IM. As a consequence, the preload on the heart was greater during IM. Changes in systolic blood pressure were comparable in the 2 situations. The immersion-related decrease of heart rate was seen during STEP, but not during IM. Nevertheless, the hemodynamic responses to the initial stages of STEP up to the ankle joint were quite similar to those observed during immediate immersion to the neck. CONCLUSION: The cardiovascular responses to IM and STEP differed between protocols and even among subgroups within the same protocol. The findings further suggest that isolated immersion of body extremities can be beneficial to patients with coronary artery disease as preliminary preparation before complete water immersion is undertaken.