Intraoperative vs postoperative morphine improves analgesia without increasing PONV on emergence from ambulatory surgery

Effect of Analgesia Administration Timing on Early Post-operative Period Characteristics: A Randomized, Double-blind, Controlled Study

This study investigated the effect of time of analgesia administration in 64 patients undergoing total abdominal hysterectomy. Patients received standard general anaesthesia and were divided randomly into two equal groups. At the time of fascia closure, patients in the intra-operative (Iop) group received 0.5 mg/kg pethidine intravenously. On arrival in the post-anaesthesia care unit, the same dose of pethidine was given to patients in the post-operative (Pop) group. All patients then used a patient-controlled analgesia pump to administer pethidine analgesia as required. Times to extubation, response to verbal stimulation and orientation, post-operative pain scores and analgesic consumption were recorded. Times to extubation and response to verbal stimulation were significantly longer in the Iop group. Pain scores, analgesic consumption and additional analgesic requirements were significantly higher in the Pop group in the first 2 h post-operatively. In conclusion, intra-operative administration of pethidine provided better pain management than post-operative administration.

Practice trends in use of morphine for control of intraoperative pain: An audit

Background:

When using morphine as the sole analgesic during conduct of anesthesia, the fear of its adverse postoperative effects primarily sedation and respiratory depression may impede adequate dosing and analgesia.

Aim and Objectives:

This audit aims to explore the dosing schedules of morphine used during general anesthesia in our institution and to analyze whether the fear of major side effects leads to suboptimal dosing of morphine with inadequate pain relief.

Materials and Methods:

All subjects scheduled for surgery under general anesthesia wherein morphine was used exclusively for intraoperative analgesia were included in the audit. The audit proforma was completed by the attending anesthesiologist wherein the study period extended from beginning of anesthesia to immediate postoperative period.

Result:

The study population comprised of 158 patients having mean age 33 ± 14 years and mean weight 52 ± 14 kg. The dose of morphine administered at induction varied widely from 0.05 to 0.3 mg/kg i.v. The VAS (Visual Analogue Scale) score in immediate postoperative period varied from 0 to 10 (mean 1.7 ± 2.0) and sedation score from 1 to 5 (mean 3.94 ± 1.05). Inadequate analgesia with a VAS score ≥4 was seen in 15% patients. Morphine dosage of >0.1 mg/kg was associated with highly significant increase in quality of postoperative analgesia with VAS score <4, and an increase in sedation with sedation score ≤3 (P value < 0.01). However, none of the patients required active intervention for cardiorespiratory support.

Conclusion:

The practice of dosing morphine in our institution is highly variable with doses ranging from 0.05 to 0.3 mg/kg. This results in inadequate analgesia in 15% patients in postoperative period. Titrating the dose of morphine to expected pain levels inflicted upon by surgical procedures may result in better pain control and less sedated patients postoperatively.

The potential for mu-opioid receptor agonists to be anti-emetic in humans: a review of clinical data

In animal models of vomiting, mu-opioid (MOP, OP(3)) receptors mediate both emesis and anti-emesis. mu-receptors within the blood-brain barrier, mediating anti-emesis, are more rapidly accessible to lipid-soluble mu-opioid receptor agonists such as fentanyl than to morphine, and fentanyl has broad-spectrum anti-emetic effects in a number of species. Whether a similar situation exists in humans is not known. A search was performed for clinical studies comparing the emetic side effects of opioids administered peri-operatively in an attempt to identify differences between morphine and more lipid-soluble mu-receptor-selective agonists such as fentanyl. Overall, the evidence appears to suggest that fentanyl and other phenylpiperidines are associated with less nausea and vomiting than morphine, but not all studies support this, and fentanyl-like drugs are associated with nausea and vomiting per se. Good evidence, however, exists to show that fentanyl and alfentanil do not cause more nausea and vomiting than the ultra fast-acting remifentanil. Because remifentanil is cleared rapidly post-operatively, such trials suggest that the emetic side effects of fentanyl and alfentanil are minimal. The clinical evidence, although limited, is at least consistent with the possibility that central mu-opioid receptors may mediate anti-emesis in humans. It is possible that the role of mu-opioid agonists in anti-emesis may become clearer in the future as a result of the use of peripheral mu-opioid receptor antagonists.

Morphine delays discharge following ambulatory surgery: a prospective institutional study

INTRODUCTION

Morphine is used regularly in day surgery despite its known side-effects. We assessed whether this delayed discharge.

PATIENTS AND METHODS

100 patients were divided into 2 groups: 50 patients received morphine and 50 patients received non-morphine analgesia. Demographic data and reasons for delayed discharge were recorded.

RESULTS

73% of all major cases received morphine compared to only 19% of minor cases. Operative and recovery times were significantly greater in the morphine group. 58% of patients given morphine had a delayed discharge compared to 14% of patients not given morphine.

CONCLUSIONS

Morphine use in day surgery is associated with increased operating and recovery times and higher rates of delayed discharge.