Effect of dopexamine on calculated low gastric intramucosal pH following valve replacement

Gastric tonometry was used to study the possible effect of dopexamine infusion on a low calculated intramucosal pH (pH_i) as a sign of splanchnic ischemia.
Measurements were made during surgery and for approximately 18 hours postoperatively on 19 non-selected adult patients undergoing valve replacement. Patients developing a postoperative pH_i >7.30 were randomized to receive dopexamine (2 μg · kg^-1 min^-1) or placebo in a double blind fashion. Eighteen patients wore randomized, 10 to receive dopexamine and 8 to placebo.
The calculated pH_i remained unchanged for the first 2 hours in both groups. After 4 hours a significant ( P <0.05) decrease in pH_i was noted in the dopexamine group which remained significantly below the placebo group during the monitoring period. The dopexamine treated patients had a significantly longer period of low pH_i but the pH-gap i.e. the difference between arterial pH and pH_i did not differ between the two groups. Patients with postoperative complications, defined as infections (2), myocardial infarction (1), single- (2) or multiple organ failure and death (1), did not have longer periods with pH_i below 7.30. In these patients, however, a pH-gap >0.12 occurred more often than in those without complications, indicating that an increased incidence of complications was related to a pH-gap >0.12.
It is our opinion that true mucosal ischemia is best detected by estimating the difference in carbon dioxide tension between arterial blood and mucosa. This can be expressed either directly as PCO₂-gap (P_tonCO₂-P_aCO₂) or indirectly as pH-gap.     

Differential effects of dobutamine, dopamine, and noradrenaline on splanchnic haemodynamics and oxygenation in the pig

Supranormal oxygen (O₂) transport may benefit critically ill patients. Catecholamines are clinically employed for this purpose. However, their effects on splanchnic haemodynamics and oxygenation are not well defined. The effects of dobutamine (DOBU), dopamine (DOPA), and noradrenaline (NA) on splanchnic blood flows (electromagnetic flow probes), O₂ deliveries and uptakes (catheterisation of portal and hepatic veins) were studied in nine anaesthetised (ketamine/flunitrazepam), ventilated, paralysed, and laparotomised pigs. All three catecholamines (DOPA at 15 μg·kg^-1 · min^-1, DOBU at 13 μg · kg^-1 · min^-1, NA at 0.4 μg · kg^-1 · min^-1) significantly ( P <0.05) increased cardiac output and systemic O₂ delivery. Only DOPA increased small intestinal and total hepatic blood flows, and O₂ deliveries, and decreased O₂ extractions. The same parameters did not change during DOBU. During NA, total hepatic blood flow and O₂ delivery decreased, and hepatic O₂ extraction increased. During all three catecholamines, small intestinal and total hepatic O₂ uptakes did not change significantly. Whereas hepatic arterial blood flow decreased during both DOPA and NE, portal venous flow increased during DOPA. These data suggest that in the experimental model used splanchnic O₂ supply and O₂ reserve capacity appear improved by DOPA, unaffected by DOBU, and impaired by NA.     

Contradictory effects of dopamine at 32°C in pigs anesthetized with ketamine

Background: In critically ill patients who were surface cooled to 332C, we have observed that dopamine sometimes causes a substantial decrease in blood pressure. The present study was designed to compare the effects of dopamine in normothermia to those seen after surface cooling to 32C.
Methods: Seven pigs with a mean body weight of 21 kg were anesthetized with ketamine and muscle relaxation was induced with pancuronium. They were mechanically ventilated and given dopamine infusions (5 and 12 μg · kg^-1 min^-1) in normothermia and after surface cooling by cold water immersion to a central blood temperature of 320C (range 31.6–32.6C).
Results: In normothermia, dopamine at a dose of 5 μg · kg^-1 min^-1 increased mean arterial blood pressure (MAP) by 16% ( P < 0.01) and cardiac output (CO) by 9% ( P =0.051); at 12 μg kg^-1 min^-1 dopamine increased MAP by 26% ( P < 0.01) and CO by 18% ( P < 0.01). In hypothermia, MAP and CO did not change at an administration rate of 5 μg kg^-l · min^-1; at 12 μg · kg^-1 min^-1 CO was unchanged but MAP was significantly reduced by 15% ( P < 0.01).
Conclusion: Dopamine increased CO and MAP in normothermia but not at 32C, where there was even a significant reduction of MAP in this porcine model.     

Intestinal Vascular Responses to Dopamine During Fentanyl-Nitrous Oxide Anaesthesia, Supplemented with Dixyrazin

Intestinal haemodynamics in response to continuous i.v. administration of dopamine were investigated in cats anaesthetized with fentanyl-nitrous oxide either with or without supplement of dixyrazin. A dose-dependent vasodilatation was observed in the dopamine dose range 2.5–35 μg-kg^-1 min ^-1 and the subsequent maximal intestinal blood flow increase was 121%. No net intestinal vasoconstriction was evident even at the largest dopamine doses, although the vascular response reached a plateau at 17.5 μg-kg^-1 min^-1. Control experiments during chloralose anaesthesia gave similar results. Changes in mean arterial pressure and heart rate were small. Renal blood flow was virtually unchanged at dopamine doses below 10 μg-kg^-1 min^-1, while renal vasoconstriction was evident following dopamine doses above that level. The addition of i.v. dixyrazin (0.15-0.30 mg kg^-1) to the fentanyl-nitrous oxide anaesthesia substantially potentiated the intestinal vasodilator response to i.v. dopamine and the maximal blood flow increase was 183% at 10–15 μg kg^-1 min^-1. In vitro experiments using mesenteric resistance vessels from the rat demonstrated a dose-dependent relaxation to dopamine. At very large doses this response was counteracted, but not reversed into vasoconstriction by dopamine-induced a-adrenergic stimulation.     

Interstitial fluid accumulation does not influence oxygen uptake in the rabbit small intestine

Crystalloid resuscitation increases interstitial fluid volume. Intestinal ischemia and impaired barrier function may contribute to the precipitation of multiple organ failure. Accordingly, the intestine was chosen as target organ to test whether interstitial oedema impairs oxygen extraction by the tissue.
The portal vein in anaesthetized rabbits was partially obstructed for 30 min along with an intravenous infusion of 0.9% saline 60–90 ml kg^-1 (oedema group, n = 7). Total water content of the small intestine increased from 3.4 ml g^-1 dry weight in control (n = 8) to 3.9 ml g^-1 in the oedema group ( P = 0.049). Small intestinal O₂ uptake was calculated from the arteriovenous O₂ content and electromagnetic flow measurements in the superior mesenteric artery. Mesenteric flow was reduced stepwise by a snare occluder around the artery. Intestinal oxygen-ation was monitored indirectly as well, by means of mesenteric venous lactate, arterial base excess and by mucosal pH (pH_i) assessed tonometrically.
The oxygen extraction ratios were similar in the oedema and control group at similar oxygen supplies. After a 45 min flow reduction to 15% of baseline mesenteric venous lactate and pH_i did not differ between the groups. pH; averaged 7.31 and fell to 6.74. Below an intestinal O₂ uptake of 2.5 ml min^-1, pH_i correlated somewhat better with O₂ uptake (r=0.66) than did arterial base excess (r=0.50).
The results indicate that acute elevation of extracellular volume to the extent in the present study, does not impede oxygen uptake in the gut.     

Multiple Dose Kinetics of Ketobemidone in Surgical Patients

Twelve patients scheduled for major abdominal surgery were selected for a study of the kinetics of ketobemidone during the day of surgery and in a follow-up study 3–5 days after surgery. In six patients ketobemidone was administered as ketobemidone plain and in the other six, it was given as Ketogin®, a combination formula containing a spasmolytic substance in addition to ketobemidone. Plasma samples were collected for approximately 24 h following induction of anesthesia, during which time multiple doses of ketobemidone were administered. A single-dose study was performed 3–5 days after surgery using the same drug. No significant differences were found between the two formulations of ketobemidone. Plasma clearance did not change significantly between the two periods of study, being 18.0±4.4 ml · kg^-1 · min^-1 peroperatively and 21.7±7.6 ml · kg^-1 · min^-1 postoperatively. Peroperative V_{d area} was significantly larger than post-operative V_{d area}, 5.84±2.621 · kg^-1 and 3.63±0.381 ·; kg^-1, respectively. T1/2 terminal decreased from 3.84±1.6 h peroperatively to 2.06±0.44 h postoperatively.     

Cardiovascular depression by isoflurane and concomitant thoracic epidural anesthesia is reversed by dopamine

Interactive effects between exogenous dopamine (DA) and isoflurane (I) combined with thoracic epidural blockade (TEA) were studied in dogs during chloralose anesthesia. The I–TEA intervention per se decreased heart rate (HR; 28%), mean arterial pressure (MAP; 63%), cardiac output (CO; 54%), left ventricular dP/ dt (LVdP/dt; 75%) and LVdP/dt/systolic arterial pressure (SAP; 42%). Prior to the I–TEA intervention , dopamine increased MAP, CO, LVdP/dt, LVdP/dt/SAP and stroke volume (SV) already at the dose 10 μg–kg^-1. min^-1 and, additionally, increased mean pulmonary artery pressure (MPAP) at the dose 20 μg–kg^-1. min^-1. During the I–TEA intervention , the DA–induced increases in MAP and systemic vascular resistance (SVR) were significantly higher than prior to I–TEA, as indicated by significant ANOVA interactive effects. At the dose 10 μg–kg^-1 min^-1, DA restored MAP, CO, LVdP/dt, LVdP/dt/SAP and SV to levels found before the I–TEA intervention, while HR was restored first at the dose 20 μg–kg^-1 –min^-1. At the dose 20 μg–kg^-1–min^-1, DA also increased MAP (39%), LVdP/dt (119%), LVdP/dt/SAP (73%), SVR (28%) and MPAP (70%) above levels prior to I–TEA. To conclude, exogenous dopamine effectively and dose–dependently counters cardiovascular depression induced by the anesthetic technique of combining I and TEA. The pressor and systemic vasoconstrictor actions of dopamine are potentiated by conjoint administration of I and TEA.     

Intramuscular dexmedetomidine premedication—an alternative to midazolam-fentanyl-combination in elective hysterectomy?

Sedation, anxiolysis, intubation responses and fentanyl anaesthetic requirements were investigated in a double-blind, randomized study in twenty ASA I-II elective hysterectomy patients. Ten patients received dexmedetomidine 2.5 μg kg^-1 i.m. 60 min before induction and saline placebo i.v. 2 min prior to induction (= DP group). Ten patients received midazolam 0.08 mg kg^-1 i.m. 60 min and fentanyl 1.5 μg kg^-1 i.v. (= MF group) 2 min before induction of anaesthesia with thiopentone 4 mg kg^-1. Anaesthesia was maintained with 70% nitrous oxide in oxygen and with fentanyl 2 μg kg^-1 i.v. increments according to predetermined criteria. Both premedications induced sedation ( P < 0.01 in both groups) and anxiolysis ( P < 0.01 in DP vs <0.05 in MF group) without any differences between the groups. Haemodynamic changes following tracheal intubation did not significantly differ between the groups. Intraoperatively systolic and diastolic arterial pressure were 15% and 13% lower in DP group ( P < 0.01 and P < 0.05 for drug effect), the mean heart rate was approximately 9 beats min^-1 lower in DP group (n.s.). Fentanyl was required more often in MF group: median 3.5 (QD 1.5) vs. 2.5 (QD 0.5) times in DP group ( P < 0.05), the total amount being 57% smaller in DP group: 0.03 (QD 0.01) vs. 0.07 (QD 0.02) μg kg^-1 min^-1 ( P < 0.05). Postoperative course and analgesic requirements were similar in both groups. Dexmedetomidine premedication may offer an alternative to current anaesthesia practice in elective hysterectomy.     

Effects of organic nitrate vasodilators on platelet function before and after cardiopulmonary bypass

Various in vitro , ex vivo and in vivo tests have shown that organic nitrates attenuate platelet function. Because organic nitrates are commonly administered to patients undergoing cardiac surgery, the postoperative bleeding tendency observed in these patients might be strengthened by nitrates. Therefore, we compared the acute effects of nitroglycerin (0.5 μg kg^-1 min^-1) and isosorbide dinitrate (0.5 or 2.5 ng kg^-1 min^-1) with those of placebo on platelet function both before and after cardiopulmonary bypass in 40 patients undergoing coronary artery bypass grafting (CABG). Bleeding time, platelet retention on glass beads, i.e. platelet adhesiveness, and thromboel-astograph tracings were used as indicators of platelet function. Although nitroglycerin and isosorbide dinitrate induced significant haemodynamic changes, e.g. decreases in arterial and pulmonary arterial pressure, they had no significant effects on the indices of platelet function. We conclude that, when given in haemodynamically effective doses, neither nitroglycerin nor isosorbide dinitrate have any measurable acute effect on platelet function as evaluated with on-site tests in patients undergoing CABG surgery.     

A comparison of the effects of fentanyl and propofol on left ventricular contractility during myocardial stunning

Background : The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could protect the heart and improve recovery of ventricular contractile function in open-chested dogs.
Methods : Twenty adult beagles were acutely instrumented, under halothane anaesthesia, to measure ECG; aortic, left ventricular pressures; cardiac output; coronary flow; and segmental lengths in the regions perfused by the left anterior and left circumflex coronary arteries. After surgery and a stabilisation period halothane anaesthesia was terminated and fentanyl (100 μg. kg^-1 bolus followed by 2 μ.kg^-1·min^-1 infusion; n=10) or propofol (5 mg. kg^-1 bolus followed by 0.3 mg· kg^-1 min^-1 infusion; n=10) anaesthesia commenced. After a stabilisation period the LAD coronary artery was occluded for 10 min and then reperfused for 3 h. Measurements were taken throughout the protocol.
Results : We found no significant difference in recovery of contractile function between propofol and fentanyl as assessed by normalised preload recruitable work area (50±10 vs 47±16%), normalised systolic shortening (36±12 vs 48±14%) and peak left ventricular dP/dt (1665±276 vs 1846±151 mmHg.s^-1) at the end of reperfusion.
Conclusion : We conclude that at the concentration used in this study propofol shows no improvement in contractility during "stunning" when compared to fentanyl.     

The Venturi Anaesthesia Circuit II Carbon Dioxide Production and Gas Flow Requirements

Carbon dioxide production was measured in 20 adult patients undergoing alloplastic operation of the hip. Body weight ranged from 40 to 81 kg. Anaesthesia consisted of lumbar plexus block, i. v. diazepam, pethidine, pavulon and N₂O/O₂ under controlled ventilation. CO₂ production was 2.13 ml kg^-1 min^-1 (interquartile range 2.09-2.23). A fresh gas flow rate of about 30 ml kg^-1 min^-1 was required for the elimination of CO₂ produced when using the Venturi system for inhalation anaesthesia.     

Advantages of Glycopyrrolate over Atropine during Reversal of Pancuronium Block

Atropine 0.015 mg kg^-1 and glycopyrrolate 0.0075 mg kg^-1 were compared as antimuscarinic agents during reversal of pancuronium block with neostigmine 0.03 mg kg^-1 in 30 patients anaesthetized with thiopental—N₂O-fentanyl and undergoing minor surgery. The decrease of heart rate was more pronounced in patients who received atropine-neostigmine. The mean of the lowest heart rate was 44.3 beats min^-1 in the atropine group compared with 54.3 beats min^-1 in the glycopyrrolate group. Five patients treated with atropine-neostigmine developed a transient nodal rhythm as compared with two of those receiving glycopyrrolate-neostigmine (non-significant difference). Recovery from anaesthesia, as assessed by the awakening after the discontinuation of N₂O administration, was more rapid in patients given glycopyrrolate. In conclusion, glycopyrrolate seems to have advantages over atropine when used during reversal of pancuronium block with neostigmine.     

Effects on skeletal muscle oxygenation and capillary blood flow by adenosine-, sodium nitroprusside- and acetylcholine-induced hypotension

Background: Adenosine (ADO)-induced hypotension during diethyl ether anesthesia has been shown to increase skeletal muscle oxygenation. Whether this beneficial effect of ADO hypotension is present also during another anesthetic technique was tested in the present study using ketamine-xylazine anesthesia, and its actions were compared with sodium nitroprusside (SNP) and acetylcholine (ACh) induced hypotension in rabbits.
Methods: Local oxygen pressure and capillary blood flow were measured with a multiwire microelectrode which was placed on the surface of the left vastus medialis muscle. The experiments were performed in three groups, in which either ADO, SNP or ACh was infused into a central vein in a dose that produced a reduction of the mean arterial pressure by 20–25%, to approximately 60 mmHg.
Results: In the ADO group (60–170 μg kg^-1 min^-1) the tissue oxygen pressures increased by 23% while capillary blood flow decreased by 38%. During SNP administration (1–3 μg kg^-1 min^-1) the oxygen pressures decreased by 21% and an increase of 31% in capillary flows was seen. When ACh was infused (1–4 μg kg^-1 min^-1) the oxygen pressures decreased by 21% and, in parallel, capillary blood flow decreased by 50%. During hypotension no low tissue oxygen pressure values (<1.5 kPa) were found in the ADO group, whereas they were present in both the SNP and ACh group.
Conclusion: Compared to sodium nitroprusside and acetylcholine, adenosine appears to have an oxygen-sparing effect in the skeletal muscle during pharmacologically induced hypotension.     

Antinociceptive effect of perioperative adenosine infusion in abdominal hysterectomy

Background: Adenosine (ADO), and stable analogs thereof, have been shown to exert antinociceptive action in cutaneous and deep somatic pain under experimental and clinical conditions in animals and in humans. The aims of this randomized double-blind placebo-controlled study were to evaluate if a low dose of intravenous (i.v.) ADO could reduce the requirements of volatile anesthetic and postoperative opioid in connection to hysterectomy, where visceral nociception significantly contributes to pain.
Methods:
Forty-three women, age 32–65 years, ASA I and 11, scheduled for abdominal hysterectomy, were assigned to receive an i.v. infusion of either adenosine, 80 μg. kg^-1 min^-1, or placebo during surgery. Anesthesia was maintained with isoflurane (ISO)/N₂O/ O₂ inhalation. Postoperatively, a reduced dose of 40 μg. kg^-1. min^-1 was continued for 3 h.
Results: The end-tidal (ET-) IS0 was equal between groups before surgery. During surgery, the IS0 requirement was increased, compared to the preoperative level, in the placebo group, while the requirement declined in the ADO group. The overall IS0 requirement in the ADO group was reduced by 36% (P<0.002). The first 24 h postoperative opioid requirement, with equal resting pain in both groups, was 18% ( P < 0.05)lower in the ADO group.
Conclusion: A low dose of perioperative adenosine infusion in abdominal hysterectomy reduces the requirements of volatile anesthetic and postoperative opioid analgesic.     

Cardiovascular Effects of High-Dose Fentanyl Anaesthesia

An anaesthetic technique using high-dose fentanyl for coronary artery surgery is described. Fentanyl 160 or 70 μg kg^-1 was used as the sole anaesthetic agent, and patients were ventilated with air/O₂ (fentanyl 70 μg kg^-1) or N₂O/O₂ (fentanyl 60 μg kg^-1). Cardiovascular data from 30 patients are presented. Fentanyl caused no significant cardiovascular depression. The only statistically significant changes in cardiovascular parameters were seen in the patients who received fentanyl 60 μg kg^-1. Five minutes after skin incision there was an increase in peripheral resistance. Diastolic pressure was increased following sternotomy. Problems associated with this technique of anaesthesia are a 50% incidence of hypertension following sternotomy (requiring treatment with sodium nitroprusside) and prolonged respiratory depression. The lack of cardiovascular depression produced by fentanyl and the ability of fentanyl to reduce hormonal and metabolic responses to surgery make it a satisfactory technique for cardiac anaesthesia.     

Isosorbide dinitrate does not interfere with heparin anticoagulation:

The possible nitrate-induced heparin resistance was studied intraoperatively in 40 patients undergoing coronary artery bypass grafting. The patients were randomized to receive a continuous infusion of placebo, nitroglycerin (0.5 μg kg^-1 min^-1) or isosorbide dinitrate (0.5 or 2.5 μg kg^-1 min^-1). After the infusion had been administered, prior to the institution of cardiopulmonary bypass, for at least 60 min, porcine intestine heparin 300 I.U. kg^-1 (as divided in two consecutive doses of 100 and 200 I.U. kg^-1, respectively) was administered to achieve systemic anticoagulation. Activated coagulation time values and plasma heparin anti-X_a activity showed no significant differences between the groups before and after the administration of heparin. It is concluded that in doses given in the present study, organic nitrates do not interfere with the anticoagulation effect of large doses of heparin required for the conduction of cardiopulmonary bypass.     

Haemodynamic Responses to Antagonism of Pancuronium and Alcuronium Block

Using non-invasive methods, haemodynamic responses to antagonism of pancuronium (Pc) and alcuronium (Ac) block were compared in patients anaesthetized with thiopental-N₂O-fentanyl and undergoing minor surgery. Neuromuscular block (90%) was maintained with Pc in 10 patients and Ac in 10 patients. After surgery, atropine 0.015 mg kg^-1 and neostigmine 0.03 mg kg^-1 (AN) were given simultaneously. The rate of reversal of the block was equal in the two groups. Between 4 and 16 min after AN, the decrease of heart rate (HR) was more pronounced in patients who had received Pc. The mean of the lowest HR was 43.2 beats min^-1 in the Pc group, compared with 62.0 beats min^-1 in the Ac group. The bradycardia was associated with a moderate decrease in arterial pressure in patients treated with Pc. However, due to an increase in stroke volume, mean cardiac output (CO) was not lower in the Pc group. Some patients treated with Pc developed a temporary nodal rhythm after AN and this was associated with a considerable decrease in CO. It is concluded that, in spite of marked bradycardia during antagonism of Pc block, circulation is well maintained, provided that sinus rhythm is present.     

Dopamine Infusion in Man. Plasma Catecholamine Levels and Pharmacokinetics

Dopamine is widely used in the treatment of hypotensive conditions and/or impending renal failure, but the plasma levels of dopamine and other catecholamines in association with dopamine infusion are not known. Plasma catecholamines and dopamine pharmacokinetics during and after dopamine infusion were therefore studied in man. Two and 5 μg - kg^-1 - min^-1 of dopamine were infused for 30 min in two groups of five patients. Dose-dependent mean steady state levels with fairly large interindividual variations were reached within 5 min. Elimination of dopamine from plasma after termination of infusion had a biphasic course with t 1/2 around 1 min and t 1/2 β about 9 min in both groups. Noradrenaline plasma levels and blood pressure increased significantly in the 5 μg group. It is suggested that the vasoconstriction with deleterious effects on tissue perfusion, seen in conjunction with high-dose dopamine infusion, may be due to increased noradrenaline levels.     

Effects of propofol on the human heart electrical system: a transesophageal pacing electrophysiologic study

Previous studies have shown that infusion of propofol has sometimes been associated with bradyarrhythmias. To evaluate the effects of propofol on the electrical system of the heart, we carried out an electrophysiologic study with transesophageal pacing on ten healthy subjects scheduled for minor elective maxillo–facial surgery. By means of atrial pacing conducted by a progressive increase in stimulation cycles, we determined, in awake patients and during propofol anesthesia (2.5 mg kg^-1 for induction, followed by 100 μg kg^-1 min^-1 for maintenance), the correct sinus recovery time and the eventual appearance of Wenckebach atrio–ventricular block. We did not notice sinoatrial node depression or pathologic increase in the atrio–ventricular conduction.     

Effective dose of granisetron in the reduction of nausea and vomiting after breast surgery

Background: Prophylactic use of granisetron, a selective Shydroxytryptamine type 3 receptor antagonist, reduces the incidence of nausea and vomiting after breast surgery. This study was undertaken to determine the minimum effective dose of granisetron in the reduction of postoperative nausea and vomiting (PONV) in patients undergoing general anaesthesia for breast surgery.
Methods: In a randomized, double-blind manner, 120 female patients aged 42–66 years were assigned to receive either placebo (saline) or granisetron in a dose of 20 μg · kg^-1, 40 μg · kg^-1 and 80 μg · kg^-1 i.v. immediately before the induction of anaesthesia. A standard general anaesthetic technique was employed throughout. The POW and safety assessments were performed continuously during the first 24 h after anaesthesia.
Results: There were no significant differences among the groups with regard to patient demographics, surgical procedures, anaesthetics administered and analgesics given. The incidence of PONV was 47%, 43%, 17% and 17% after administration of placebo and granisetron 20 μg -kg^-1, 40 μg kg^-1 and 80 μg kg^-1, respectively. Granisetron 40 μg kg^-1 was as effective as 80 μ g - kg^-1 and both resulted in significant reductions of the incidence of PONV compared with placebo and granisetron 20 μg kg^-1 ( P < 0.05). No differences in the incidence of adverse events were observed among the groups.
Conclusion: Granisetron 40 μg · kg^-1 appears to be the minimum effective dose for reducing POW in patients undergoing general anaesthesia for breast surgery.