Oxytocin injection after Caesarean delivery: intravenous or intramyometrial?

Abstract

Purpose: To determine, after Caesarean delivery, uterine contractility and blood pressure following intravenous (iv) and intramyometrial (imy)injection of oxytocin. Methods: In a double-blind clinical trial 40 parturients scheduled for elective Caesarean section with spinal anaesthesia were randomized into two equal groups. One litre Ringer's lactate was administered iv before intrathecal injection of 1.7 ml bupivacaine 0.75% and 0.3 mg morphine. All patients received simultaneous iv and irny injections after removal of the placenta. Patients in Group I received 5 IU (I 0 IU'ml -~) oxytocin iv and 2 ml saline imy; Group 2 patients received 0.5 ml saline iv and 20 IU oxytocin into the myometrium. Baseline systolic blood pressure (SBP) and heart rate were measured before delivery and at one minute intervals for 15 min after injection of study solutions. Uterine contractility was assessed at I, 2, 4, 6, 8, 10 and 15 min after oxytocin injection. Haemoglobin concentration before surgery and on first post-operative day was also recorded. Results: Mean decrease in systolic blood pressure (SBP) one minute after oxytocin was 8.4 mmHg in Group I vs 14.6 mmHg in Group 2 (P < 0.001 ). Systolic blood pressure returned to baseline two minutes after oxytocin in Group I and after three minutes in Group 2. Uterine contractility and change in haemoglobin concentration were similar in both groups. Conclusion: Intramyometrial administration of 20 IU oxytocin after Caesarean delivery is associated with more severe hypotension than is iv injection of 5 IU oxytocin. Route of oxytocin injection did not affect uterine tone. R&ultats : La baisse moyenne de la tension art&ielle systolique (TAS), une minute apr& rinjection d'ocytocine, Etait de 8,4 mmHg dans le groupe I vs 14,6 mmHg dans le groupe 2 (P < 0,001 ). Egalement apr& rocytocine, il a fallu deux minutes pour le groupe I et trois minutes pour le groupe 2 avant de retrouver la tension art&ielle de base. La contractilitE uterine et le changement dans la concentration d'hEmoglobine ont EtE similaires dans les deux groupes. Conclusion : IJadministration intramyom&riale de 20 UI d'ocytocine aprEs une c&arienne est associEe ~ une hypotension plus sEv&e qu'avec une injection iv de 5 UI d'ocytocine. La voie d'administration de rocytocine n'a pas affectE la tonicitE uterine.

Randomized double‐blind comparison of the effects of intramyometrial and intravenous oxytocin during elective cesarean section

“…The obstetrician was allowed to freely carry out a uterine massage. Uterine tone was assessed on a 10‐point linear analog scale (0 = floppy, 10 = maximum contraction) at 2, 4, 6, 8, 10, 15, and 20 min after the injection. Moreover, we defined SBP that decreased below 20% of the value at the time of uterine incision as hypotension.…”

“…group was 2.73 mmHg lower than that of the i.m.y. group (β error = 0.2, P = 0.05, for a two‐tailed unpaired t ‐test), on the basis of a previous study . Those authors compared i.m.y.…”

“…oxytocin, few have addressed the effects of intramyometrial (i.m.y.) administration of oxytocin . In a clinical study, Dennehy et al .…”

Ocitocina em cesarianas: qual a Melhor Maneira de Utilizá-la?

“…Após a publicação de relatos de óbito materno advindo da utilização inadequada da ocitocina 38 , os autores observaram uma mudança na conduta clínica desses anestesiologistas, já que a partir de então apenas 23% mantinham a conduta anterior 41 . Em relação à via de administração, apesar da via intramiometral promover contratilidade uterina eficiente como a via venosa, ela determina maiores alterações hemodinâ-micas (hipotensão arterial e taquicardia) o que pode ser prejudicial em pacientes com baixa reserva cardíaca ou hipovolêmicas 42 . A ocitocina não é o único uterotônico disponível, porém a restrição aos demais agentes ocorre devido aos efeitos colaterais que eles determinam.…”

“…After reports of maternal death due to the inadequate use of this drug 38 , the authors observed a change in the clinical conduct of these anesthesiologists, because only 23% of them maintained the older conduct 41 . Regarding the route of administration, although the intramyometrial administration promotes uterine contractility as efficiently as the intravenous route, it causes more hemodynamic changes (hypotension and tachycardia), which can be detrimental in patients with low cardiac reserve or hypovolemic 42 . Oxytocin is not the only uterotonic available; however, there are restrictions to the other agents due to their side effects.…”