Tuesday, 31 August 2010

Abstract

Background: Sustained single operator continuous-external-chestcompressions during cardio-cerebral resuscitation (CCR) are physically demanding. Consequently, physical fatigue might induce inadequate compression rates and/or depths, and might affect the neurological and patient outcome following CCR. It might therefore be hypothesised that high caretaker cardiopulmonary fitness and/or muscle strength delays the development of physical fatigue and thus may improve CCR quality. Materials and methods: Fifteen subjects (12 nurses, 3 physicians, mean age 34±9y, body mass index 24±3kg/m2 , peak oxygen uptake capacity 2884±755mL/min, ventilatory threshold 2061±593mL/min, and maximal hand grip strength 49±11kg) performed a 15-min hands-only CCR session on an adult CCR training manikin, with assessment of compression depth and frequency. During CCR we assessed serial blood lactate concentrations, and provided continuous heart rate monitoring. Maximal and aerobic cardiopulmonary exercise capacity, maximal hand grip and dynamometry strength, and CCR quality correlations were assessed. Results: During CCR blood lactate level increased from 2.3±1.0 to 3.7±2.1mmol/L (p=0.058), and heart rate rose from 48±9 to 69±12% of maximal heart rate (p<0.001). Compression depth decreased significantly from 1 up to 10 min of CCR from 42±7 to 36±11mm (p<0.05), while compression rates during CCR remained stable. Univariate correlations indicated a significant relation between CCR quality and ventilatory threshold (r2=0.45), peak oxygen uptake capacity (r2=0.29), peak cycling power output (r2=0.29), isometric elbow extension peak torque (r2=0.30) (p<0.05). Multivariate regression analysis indicated that the ventilatory threshold was independently related to CCR quality up to the first 3 min (p<0.05), while maximal isometric elbow extension peak torque was independently associated with CCR quality after 10 min (p<0.05). Conclusion: The quality of continuous-external-chest-compressions-only CCR seems to be determined by the aerobic cardiopulmonary fitness (early stage) and muscle strength (late stage) of the CCR performing caretaker.