Post operative nausea and vomiting (PONV) has significant impact on patients and heath care providers ¹. Despite impressive advances in the field of anaesthesia 20-30% of patients continue to experience PONV within the first 24 hours ².

The vomiting reflex may be excited by many stimuli most of which are operative ³. Some of the factors associated with PONV are patient predisposition, surgical site related, opiods administration and anaesthetic drugs used. Ophthalmic surgeries are associated with increased incidence of nausea and vomiting ⁴. Nausea and vomiting can induce ketosis in diabetic patients undergoing vitrectomy for advanced diabetic retinopathy ⁵.

Droperidol is frequently used in the United States of America and Europe as a prophylactic drug against PONV ^6-7. It is a well-tolerated drug, inexpensive, and has few side effects. The Food and Drug Administration had mandated that the manufacture or the generic formulation of droperidol place a black box warning regarding the risk of serious proarrhythmogenic effects ⁸.

The aim of this study was to study the safety and efficacy of droperidol in relieving PONV in diabetic patients undergoing pars plana vitrectomy.

A prospective randomised double blind study. 120 patients were enrolled in the study. All of them underwent pars plana vitrectomy at King Hussein Medical Center, Ophthalmology Department in the period between May 2004 and October 2005.
All patients had standard three port pars plana vitrectomy due to advanced diabetic retinopathy. Patients were divided into two groups; the first group was given low dose droperidol (10 micrograms/kg diluted in 10 millilitres normal saline 0.9%) ten minutes before the end of surgery. The control group was given 10 millilitres of normal saline 0.9% as a placebo.

Randomisation was done by sealed envelope technique. Patients receiving antiemetic or patients who were suffering from nausea or vomiting during the last two weeks before surgery were excluded from the study. All patients fasted starting from 10 pm, the night before the surgery.

General anaesthesia was standardised. After insertion of an intravenous line, fentanyl (1-2 microgram/kg) and propofol (2mg/kg) were used for induction. Laryngeal mask was used and vecuronium (0.1mg/kg) was used as muscle relaxant. Neuromuscular monitoring was done. Drugs were repeated as indicated to reduce the need for an antagonising neuromuscular agent (atropine 0.5mg and neostigmine 0.1mg/kg). Anesthesia was maintained using sevoflurane at an end expiratory concentration of 1%. The lungs were ventilated with O2/N2O in a fraction of 0.3: 0.7 using fresh gas flow at 1 litre /minute. Ventilation was adjusted to keep end tidal carbon dioxide within the normal range (36-40mmHg). No local anaesthesia was given by the surgeon.

Vital signs were regularly monitored. Two hours after recovery, patients were transferred to the surgical word. Patients were monitored for the occurrence of nausea and emetic episodes defined as retching or vomiting at 2, 4, 6, 12, 24 hours. Medical records were screened for PONV. Nausea and vomiting was assessed on a rating scale as: 0 - no nausea, no vomiting, 1 - nausea without vomiting (mild), 2 -nausea with vomiting less than three times (moderate), 3 -nausea with vomiting more than three times (severe).

120 patients were enrolled in the study. The mean age was 66.4 years. Females slightly outnumbered males (62 vs. 58).

Table I shows demographic data and patient characteristics. There is no relevant difference among the groups.

The number of patients suffering from nausea and vomiting was significantly lower in the droperidol group than in the placebo group (25% vs. 38.3%, P value < 0.01).

Table III shows the incidence of side effects. There was no increase in the incidence of arrhythmias or cardiovascular side effects with droperidol. 0.5% of the droperidol group experienced mild restlessness. Headache was more frequent in the placebo group. Intraocular bleeding was diagnosed in three patients in the droperidol group and five patients in the placebo group.

Opiods were not used as they may sensitise the vestibular apparatus and affect the incidence of postoperative nausea and vomiting ⁹.

In this study droperidol has been shown to be effective in reducing PONV in vitreoretinal surgery compared with placebo. This is in accordance with previous studies in ophthalmic surgery ^10-11. More patients in the control group experienced PONV; this was statically significant (p value < 0.01). The incidence of severe nausea and vomiting was 5% in the droperidol group and 13.3% in the placebo group. (See Table II for more details).
There were no significant side effects including neurological and extrapyramidal problems.
Restlessness, though, was more prevalent in the droperidol group but it was not statically significant (0.3<p<0.5). Headache was significantly less in the droperidol group (0.05<p<0.02); this was true for mild to moderate headache but not for severe headache. Droperidol seemed to be protective against headache.

As the Food and Drug Administration mandates that manufactures droperidol place black box warning regarding the risk of proarrhythmogenic effects. We observed patients thoroughly for cardiac side effects. There was no significant difference in cardiac status among the two groups. Our results confirmed what was reported in a study done by Henzi and his colleagues ¹².

All patients who had postoperative intraocular bleeding had PONV or retching. Patients with intraocular bleeding who didn't receive droperidol slightly outnumbered those who received it but this was not significant (0.3<p<0.5).
In conclusion, droperidol is a cost effective drug compared with other antiemetic therapy ¹³. It is considered to be an efficacious and safe drug to be used in patients undergoing vitreoretinal surgery.

Table 1. Patient characteristics and demographic data.

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Table 2 Incidence and severity of post operative nausea and vomiting during 24 hours observation period.

* P value < 0.01

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Table 3 Incidence of side effects.

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