Impact of physical fitness and biometric data on the quality of external chest compression: a randomised, crossover trial
1 Department of Anaesthesiology, Emergency and Intensive Care Medicine, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
2 Department of Anaesthesia and Intensive Care Medicine, Evangelisches Krankenhaus Weende, Göttingen, An der Lutter 24, 37075 Göttingen, Germany
3 Department of Orthopaedics and Trauma Surgery, University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany
4 Department of Anaesthesia, HELIOS-Klinikum, Emil-von-Behring, Berlin, Walterhöfer Straße 11, 14165 Berlin, Germany
5 Department of Anaesthesiology, Emergency and Intensive Care Medicine, Section of Sports Medicine, Georg-August University of Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
6 Department of Anaesthesia, Paediatric Intensive Care and Emergency Medicine, Children's Hospital auf der Bult, Janusz-Korczak-Allee 12, 30173 Hannover, Germany
BMC Emergency Medicine 2011, 11:20 doi:10.1186/1471-227X-11-20Published: 4 November 2011
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.
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.
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.
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.