Author(s): MORGADO, J.P., BHUDARALLY, M.1, FEBRA, C.2, ATALAIA, T.3, PEREIRA, H.1,2, GUERRA, J.3, PALMEIRA, A.1, ALEIXO, P.1, Institution: UNIVERSIDADE LUSÓFONA DE HUMANIDADES E TECNOLOGIAS, Country: PORTUGAL, Abstract-ID: 313

INTRODUCTION:
The guidelines of the American Heart Association and the European Resuscitation Council (ERC) (Perkins et al., 2021) for improving Cardiopulmonary Resuscitation (CPR) procedures applied to cases of cardiopulmonary arrest have recently been updated. During these procedures, chest compressions (CT) are essential to maintain continuous blood supply to the heart and brain (Chi et al., 2008). Depending on the clinical scenario, a resuscitator can perform CPR kneeling (patient on the floor outside the hospital setting) or standing (with or without a stool, with the patient on a bed in an emergency unit).
Kinematic analysis of the resuscitated patient in two situations with different bed heights (63 cm and 37 cm) revealed that there were no differences in the compression forces and their depths (Chi et al., 2008) compared. On the other hand, another study (Parent-Nichols et al., 2021) also analysed the effects of bed height on the resuscitators kinematics during standing CPR.
According to the ERC guidelines, the resuscitator who performs CT should be resuscitated at least every 2 minutes. If there is fatigue and/or less effective CT, the resuscitator should be surrendered earlier.
Our purpose was to compare the physiological impact of a Cardiopulmonary Resuscitation protocol performed with the patient on beds of different heights: 80 cm and 42 cm.
METHODS:
Four certified female first aid trainers with more than 5 years experience (46.0 ± 7.48 years; height 163.1 ± 3.57 cm; 80.0 ± 4.82 kg) carried out a CPR protocol of 5 periods of chest compressions interspersed with 2 minutes of recovery in 2 scenarios with different bed heights: 80 cm (H80) and 42 cm (H42). Heart rate (HR) was monitored throughout the protocol and lactatemia was analysed during the recovery periods.
Nonparametric Wilcoxon test for related samples was used to compare mean values of H80 and H42. Statistical significance was set at p<0.050.
RESULTS:
There was a tendency towards higher average values in response to H80 compared to H42 for blood lactate (H80: 4.81±1.97; H42: 2.93±0.67; p=0.068), HRTCavg (H80: 129.5±17.1; H42: 116.8±17.1; p=0.068), HRTCmax (H80: 139.9±19.1 ; H42: 126.3±20.4; p=0.068), FCCTmin (H80: 106.6 ±15.7; H42: 99.0±14.1; p=0.273) e HRRec (H80: 113.9±20.2; H42: 105.7±17.1; p=0.465).
CONCLUSION:
Higher patient bed heights (80 cm) seem to induce more resuscitator fatigue in CPR processes than lower heights (42 cm), considering the physiological indicators of lactatemia and mean and maximum exertional HR and recovery HR.
Physiological characterisation of effort and recovery will be great tools for deepening knowledge about optimising processes during CPR.
Fitness level may be a factor to determine chest compression duration and the levels of physical function, muscle strength, mass and morphology tend to decline with ageing. Future studies may adress the impact of an exercise intervention programme on the CC efficiency and induced fatigue in first aiders.