The Effect of Intrathecal Morphine Dose on Outcomes After Elective Cesarean Delivery: A Meta-Analysis
Bibliographic record
Abstract
BACKGROUND: The intrathecal morphine dose achieving optimal analgesia for cesarean delivery while minimizing side effects has not yet been deduced. In this meta-analysis, our objective was to determine whether low- or high-dose intrathecal morphine provides acceptable duration and intensity of analgesia with fewer side effects. METHODS: A literature search (PubMed, EMBASE, MEDLINE, Scopus, Web of Science, and CINAHL) was performed to identify randomized controlled trials involving patients undergoing elective cesarean delivery under spinal anesthesia comparing low-dose (LD; 50-100 μg) morphine with higher dose (HD; >100-250 μg). The primary outcome was the time for first request for supplemental analgesia. The secondary outcomes included pain scores, morphine use, maternal side effects (vomiting and pruritus), and Apgar scores. Mean differences (MDs) and odds ratios (ORs) were calculated using random effects modeling with 95% confidence intervals (CIs). RESULTS: Eleven articles met our inclusion criteria. Four hundred eighty patients were recruited in all study groups (233 patients in the HD and 247 in the LD groups). The mean time to first analgesic request was longer (MD, 4.49 hours [95% CI, 1.85-7.13]; P = 0.0008) in the HD group compared with the LD group. Pain scores (0-100 scale) at 12 hours (MD, 2.54 [95% CI, -2.55 to 7.63]; P = 0.33) as well as morphine consumption at 24 hours (MD, 1.31 mg [95% CI, -3.06 to 7.31]; P = 0.42) were not significantly different. The incidence of nausea or vomiting (OR, 0.44 [95% CI, 0.27-0.73]; P = 0.002) and pruritus (OR, 0.34 [95% CI, 0.20-0.59]; P = 0.0001) was lower in the LD group. The incidence of Apgar scores <7 at 1 minute was not different between groups (OR, 1.11 [95% CI, 0.06-20.49]; P = 0.94). CONCLUSIONS: This meta-analysis shows that HDs of intrathecal morphine prolong analgesia after cesarean delivery compared with lower doses. The MD of 4.5 hours (95% CI, 1.9-7.1 and 99% CI, 1.0-8.2 hours) of pain relief must be balanced against the increased risk of maternal pruritus and vomiting. Results from this study can be used by clinicians to weigh the benefits and potential side effects of using HDs of intrathecal morphine for cesarean delivery.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.014 | 0.026 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.017 | 0.056 |
| Bibliometrics | 0.004 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".