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.