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[Morphine analgesia by the intrathecal route]
Abstract:
30 patients for whom an epidural injection using local anaesthesia was hazardous (deformed spine) or contra-indicated (allergic to local anaesthetic agents) received an injection of 0.008 mg cm-1 of morphine chlorhydrate intrathecally. Residual pain scored from 0 to 5 was 2.5 after 10 minutes and 1.5 after 25 minutes. Thereafter there was only a simple ache which was well tolerated right up to the time of delivery. Uterine action was not changed, which allowed 27 labours to be completed vaginally, of which 23 were without forceps. There was no haemodynamic change or respiratory depression, either immediately of later, in the mother nor in the infant (there were 26 Apgar scores of 9 or more). The ratio of plasma concentrations of morphine between the mother and the fetus using radio-immunological assays was inverted as time passed. These were at 6 mg ml-1 or less, which explains the medullary characteristic of the analgesia and the absence of general repercussions. The safety that is offered by the poor diffusion of substance between the fetus and the mother and the ability to prevent secondary effects (pruritus and headache) are features that make intrathecal analgesia and interesting alternative to a conduction block in labour.
Insights
Intrathecal morphine provided effective labor analgesia for 30 patients unsuitable for epidural anesthesia. This method ensured maternal and fetal safety, with minimal side effects, offering a viable alternative for pain management during childbirth.
Area of Science:
- Obstetrics and Gynecology
- Anesthesiology
- Pharmacology
Context:
- Epidural anesthesia using local anesthetics poses risks for patients with spinal deformities or local anesthetic allergies.
- Alternative labor analgesia methods are needed for specific patient populations.
Purpose:
- To evaluate the safety and efficacy of intrathecal morphine for labor analgesia in patients with contraindications to epidural anesthesia.
Summary:
- Thirty patients received intrathecal morphine (0.008 mg cm-1) due to contraindications for epidural anesthesia.
- Effective pain relief was achieved, with residual pain scores decreasing significantly within 25 minutes.
- No adverse maternal or fetal hemodynamic or respiratory effects were observed; 26 infants had Apgar scores of 9 or more.
- Uterine activity remained unchanged, facilitating vaginal delivery in 27 cases (23 without forceps).
- Low maternal-fetal morphine plasma concentration ratios (<6 mg ml-1) correlated with central analgesia and absence of systemic effects.
Impact:
- Intrathecal morphine offers a safe and effective alternative to conventional epidural analgesia for specific laboring patients.
- The method demonstrates favorable maternal and fetal safety profiles, including minimal systemic absorption and side effects.
- This approach supports successful vaginal deliveries and can reduce the need for operative interventions.