Intraluminal pressure readings during the establishment of a positive 'tamponade test' in the management of postpartum haemorrhage

Objective To investigate the proposed mechanism by which intrauterine balloons achieve their tamponade effect of creating an 'intrauterine pressure that is greater than the systemic arterial pressure'. Design To determine the intraluminal pressures within a Bakri balloon during the establishment of a positive 'tamponade test' in the management of postpartum haemorrhage. To correlate these intraluminal pressures with contemporaneous readings of blood pressure recordings as documented from the operating theatre anaesthetic charts. Setting An obstetric unit (approximately 2400 births) in Wollongong, New South Wales, Australia. Sample Two women in whom first-line uterotonics were unsuccessful and who required a Bakri balloon to control postpartum haemorrhage secondary to an atonic uterus. Methods A DigiMano (Netech Corporation, Farmingdale, NY, USA) pressure recorder was attached via a three-way tap to a Bakri balloon. Anaesthetic charts of the two cases were reviewed retrospectively. Main outcome measures Intraluminal pressure readings were recorded after each 50-ml aliquot of normal saline had been insufflated into the balloon whilst the next aliquot was being prepared. Results There is a curvilinear relationship between the intraluminal pressure and the balloon volume. The pressure does not exceed the systolic blood pressure of the patient at the time of establishment of a positive tamponade test. Conclusions The intraluminal pressure within the tamponade balloon does not exceed the systolic blood pressure of the patient when a positive tamponade test is established.