Mild respiratory depression common after epidural morphine for C-section
Mild respiratory depression appears to be common in women given epidural morphine after caesarean delivery, a new study suggests.
Researchers prospectively assessed 100 women scheduled to undergo elective caesarean section delivery and to receive postoperative 3 mg epidural morphine. All participants were fitted with the Nellcor respiratory rate monitoring system. Respiratory depression was defined as both bradypnoea and oxygen desaturation for more than 1 minute.
Of the participants, 42 (mean age, 32.4±4.9 years) did not experience respiratory depression. These patients tended to be younger than those with the condition (n=47; mean age, 34.5±4.6 years; p=0.04). Both groups of participants had a median of 38 gestational weeks (p=0.45) and were of comparable body mass indices (26.5±3.6 vs 25.1±3.1 kg/m2; p=0.06).
There were 46 cases (52 percent) of mild and one of moderate respiratory depression. There were no reports of severe respiratory depression. The median time to the first depression event from morphine administration was 3.2 hours.
Over a median monitoring duration of 19.0 hours, 85 percent (n=76) of the participants developed at least one episode of bradypnoea (respiratory rate ≤10 breaths per minute) while 12 percent (n=11) experienced moderate desaturation.
Intramuscular tramadol was administered in 13 patients for pain relief, but no one required supplemental opioids. There was also no need for supplemental oxygen or naloxone. The proportion of patients with respiratory depression remained stable until the point of first ambulation.
Univariate analysis showed that aside from patient age, body mass index, gestational week, intraoperative fluid volume, or the use of medications such as tramadol or droperidol were not potential predictive factors for the development of respiratory depression.