IPPVcomplications of ventilation Haemodynamic complications

Venous return is dependent on passive flow from central veins to right atrium. As right atrial pressure increases secondary to the transmitted increase in intrathoracic pressure across compliant lungs, there is a reduction in venous return. This is less of a problem if lungs are stiff (e.g. ARDS) although it will be exacerbated by the use of inverse I:E ratio and high PEEP. As lung volume is increased by IPPV the pulmonary vasculature is constricted, thus increasing pulmonary vascular resistance. This will increase diastolic volume of the right ventricle and, by septal shift, impedes filling of the left ventricle. These effects all contribute to a reduced stroke volume. This reduction can be minimised by reducing airway pressures, avoiding prolonged inspiratory times and maintaining blood volume.

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