Maternal collapse: Challenging the four-minute rule.

INTRODUCTION: The current approach to, cardiopulmonary resuscitation of pregnant women in the third trimester has been to adhere to the "four-minute rule": If pulses have not returned within 4min of the start of resuscitation, perform a cesarean birth so that birth occurs in the next minute. This investigation sought to re-examine the evidence for the four-minute rule.

METHODS: A literature review focused on perimortem cesarean birth was performed using the same key words that were used in formulating the "four-minute rule." Maternal and neonatal injury free survival rates as a function of arrest to birth intervals were determined, as well as actual incision to birth intervals.

RESULTS: Both maternal and neonatal injury free survival rates diminished steadily as the time interval from maternal arrest to birth increased. There was no evidence for any specific survival threshold at 4min. Skin incision to birth intervals of 1min occurred in only 10% of women.

CONCLUSION: Once a decision to deliver is made, care providers should proceed directly to Cesarean birth during maternal cardiac arrest in the third trimester rather than waiting for 4min for restoration of the maternal pulse. Birth within 1min from the start of the incision is uncommon in these circumstances.