Effects of rescuer position on the kinematics of cardiopulmonary resuscitation (CPR) and the force of delivered compressions.

BACKGROUND: Depending on the clinical setting, rescuers may provide CPR from a kneeling (if the patient is on the ground) or standing (if the patient is in a bed) position. The rescuer position may affect workload, and hence rate of fatigue and quality of CPR.

PURPOSE: This study evaluates how three common rescuer positions affect the kinematics of CPR and the force of delivered compressions.

METHODS: Subjects were 18 health care providers experienced in CPR. Each participant performed CPR from three different positions: kneeling beside the Resusci Anne manikin placed on the floor (F); standing beside the manikin placed on a Table 63 cm in height (H), and standing beside the manikin placed on a Table 37 cm in height (L). The compression to ventilation ratio was 15:2. CPR duration was 5 min for each position, with a rest period of 50 min in-between. The order of position was randomised. The manikin was equipped with a six-axial force load cell to collect 3D compression forces at a sampling rate of 1000 Hz. An eight-camera Motion Analysis Digital System was adopted to collect 3D trajectory information. Data were compared using crossover-design analysis of variance (p<0.05 was regarded as statistically significant). Ratings of Perceived Exertion (RPE) were measured by modified Borg scale.

RESULTS: Significant differences were observed in the head, shoulder, lower trunk, hip and knee angles between the three methods. Lower trunk flexion angle (degrees) for H, L, and F were -14.52+/-1.13, -28.83+/-1.75, and 14.39+/-1.14, respectively. Hip flexion angle for H, L, and F were -16.21+/-3.30, -42.59+/-4.75, and -47.39+/-4.36, respectively. However, compression force (N) in H, L, and F were 455.8+/-17.6, 455.7+/-14.0, 461.5+/-13.5, respectively (p>0.05). Compression depths (mm) were: 43.5+/-3.4, 42.0+/-5.4, 44+/-5.2, respectively (p>0.05). Compression frequencies (times/min) were: 117.9+/-12.4, 116.6+/-13.4, 108.8+/-11.7, respectively (p>0.05). No differences were found between the three positions for RPE.

CONCLUSIONS: In this study, while the kinematics of CPR differed significantly with varying rescuer position, these differences did not affect the compression force, depth and frequency as performed by experienced providers.