Sternal wall pressure comparable to leaning during CPR impacts intrathoracic pressure and haemodynamics in anaesthetized children during cardiac catheterization

Aim: Force due to leaning during cardiopulmonary resuscitation (CPR) negatively affects haemodynamics and intrathoracic airway pressures (ITP) in animal models and adults, but has not been studied in children. We sought to characterize the effects of sternal force (SF) comparable to leaning force on haemodynamics and ITP in anaesthetized children. Methods: Children (6 months to 8. yrs) presenting for routine haemodynamic cardiac catheterization with anaesthesia and mechanical ventilation >6 months after cardiac transplant were studied. Haemodynamics and ITP were measured before and during incremental increases in SF of 10% and 20% body weight. Results: 20 subjects (5.4±1.7yrs of age and 18.3±3.3kg) were studied. Mean right atrial pressure (6.5±2.6 at baseline vs. 7.7±2.6 at 10% SF vs. 8.6±2.7mmHg at 20% SF), mean pulmonary capillary wedge pressure (10.2±2.9 at baseline vs. 11±3.3 at 10% SF vs. 11.8±3.4mmHg at 20% SF) and ITP (16.3±3.2 at baseline vs. 17.9±3.9 at 10% SF vs. 19.5±4cm H₂O) all increased significantly with incremental SF (p<0.001 for all). Aortic systolic pressure (85±10mmHg at baseline vs. 83±10mmHg at 10% SF vs. 82±10mmHg at 20% SF, p=0.014) and coronary perfusion pressure (42±7mmHg at baseline vs. 39±7mmHg at 10% SF vs. 38±7mmHg at 20% SF, p<0.001) both decreased significantly with incremental SF. Conclusions: In asymptomatic, anaesthetized children after cardiac transplantation, sternal forces comparable to leaning previously reported to occur during CPR elevate ITP and right atrial pressure and decrease coronary perfusion pressure. These haemodynamic effects may be clinically important during CPR and warrant further study.