Sub-hypnotic Dose of Propofol as Antiemetic Prophylaxis Attenuates Intrathecal Morphine-induced Postoperative Nausea and Vomiting, and Pruritus in Parturient Undergoing Cesarean Section

A Randomized Control Trial

Sylvanus Kampo; Alfred Parker Afful; Shiraj Mohammed; Michael Ntim; Alexis D. B. Buunaaim; Thomas Winsum Anabah


BMC Anesthesiol. 2019;19(177) 

In This Article


Obstetrics and gynecological surgeries, including cesarean section, are associated with the incidence of PONV as high as 60–83% most especially when no prophylactic antiemetic is provided.[16] This may be due to multiple complex factors such as; stimulation of uterus, broad ligament, vagina, and cervix, which may induce vomiting through afferents signals to the spinal cord along hypogastric and pelvic plexus. Surgical pain increases the circulating catecholamines, which cause PONV by stimulating area poster. Other nonanesthetic causes include surgical bleeding, medications, such as antibiotics and early motion at the end of surgery or history of motion sickness. Few anesthetic causes of PONV include hypotension, increased vagal activity, administration of neuraxial or parenteral opioids, and the addition of phenylephrine or epinephrine to local anesthetics. Also, peak block height ≥ T5, use of procaine, baseline heart rate ≥ 60 beats/min.

This study was designed to test the hypothesis that propofol use as antiemetic prophylaxis prevents intrathecal morphine-induced postoperative nausea and vomiting, as well as pruritus in parturients undergoing a cesarean section. The following principal observation emerged: First, the data indicated that sub-hypnotic dose of propofol was equally effective as metoclopramide in the prevention of PONV in parturients undergoing cesarean section under spinal anesthesia with intrathecal morphine. Second, the data showed that sub-hypnotic dose of propofol significantly reduced the incidence of postoperative pruritus following intrathecal morphine used. Some variables in this current study were kept constant for all study groups; the type of surgery, anesthesia technique, anesthetic drugs, and the level of the spinal block was all standardized, including postoperative analgesics. Duration of anesthesia and surgery were comparably the same, and there was no significant difference between age, weight, and BMI of patients from individual study groups. These, therefore, suggested that the significant difference in incidence and severity of PONV between study groups were solely attributed to the drugs tested.

Factors noted to induce emesis during cesarean delivery under spinal anesthesia includes; peritoneal traction, exteriorization of the uterus, fundal pressure during delivery of the baby and hypoxia associated with hypotension following spinal anesthesia. Pusch et al.[17] noted that emetic symptoms were reduced in patients who developed post-spinal hypotension after being given 100% oxygen, thus, implicating hypoxemia at the emetic center as a probable causative factor. This study recorded no significant changes between the groups concerning maternal blood pressure, pulse rate, respiratory rate, and oxygen saturation. The amount of ephedrine used for the treatment of hypotension was also similar between the groups. No intraoperative emesis was recorded from the study groups.

Metoclopramide is an inexpensive generic drug. As a benzamide, it acts on Dopamine 2 receptor to prevent the stimulation of the vomiting center. Its effectiveness as prophylaxis has also been confirmed.[18] Propofol is well known for its role in decreasing the incidence of PONV when used at a sub-hypnotic dose. However, the exact mechanism by which propofol prevents emesis is unknown. It has been postulated to be an antagonist at the 5HT3 receptor. Other reports suggest that the antiemetic effect of propofol is due to modulation of the subcortical pathways.[19] Patients who received propofol experienced a significant reduction in nausea and vomiting compared with patients treated with placebo. A survey demonstrated that 86% of patients who received a sub-hypnotic dose of propofol recorded no symptoms of emetic after surgery.[20] Emerging evidence also indicates that propofol, given at sub-hypnotic dose significantly decreases the incidence of emetic episodes in patients undergoing cesarean delivery with spinal anesthesia. In a study by Song et al.[16] it was demonstrated that propofol given after sevoflurane and desflurane anesthesia for outpatient laparoscopic cholecystectomy significantly decreased the incidence of PONV compared with control. Similarly, reports suggest that low-dose of propofol (0.5 or 1 mg/kg) administration at the end of surgery effectively reduce the incidence of PONV within 2 h postoperatively in highly susceptible women undergoing a laparoscopy-assisted vaginal hysterectomy and receiving opioid-based PCA.[21] In this present study, it was realized that 105 (91.30%) from the propofol group experienced no incidence of PONV compared with 7 (6.09%) parturient from the control group, a similar observation Chatterjee et al.,[22] Apfel et al.[23] and Warltier et al.[24] have also earlier submitted. Comparing the episodes and severity of PONV, the data from this study suggested that parturient who received metoclopramide (10 mg) experienced less incidence of PONV than those who received sub-hypnotic dose of propofol (0.5 mg/kg). However, the used of rescue antiemetic was higher in the metoclopramide group compared with the propofol group.

Pruritus is one of the most common adverse effects of intrathecal morphine. It is most challenging to treat and respond poorly to conventional antihistamine treatment.[25] Therefore, it remains a significant challenge for the anesthesiologist. Existing reports indicate that a low dose of propofol could alleviate morphine-induced pruritus without disrupting intrathecal morphine analgesia.[26–28] In this study, it was noted that sub-hypnotic dose of propofol decreased the incidence of pruritus compared with metoclopramide, an observation Liu et al.[29] has earlier reported. This emerging evidence, therefore, suggested that a low dose of propofol as antiemetic prophylaxis attenuate not only PONV but also, morphine-induced pruritus.