RESUMEN
Background: The induction of anaesthesia with propofol is associated with pain on injection and a significant decrease in arterial blood pressure. In this study, we compared the effect of micro-biological filter to the pretreatment with ephedrine intravenously on the incidence and severity of propofol - induced pain and on the hernodynamic responses to propofol
Patients and methods: Three hundred and seventy five [375] adult patients, of both sexes, aged 20-60 years with average weight 50-90 kg, ASA physical status I or II who were scheduled for elective day case surgery were included. Patients were randomly allocated into one of three groups. Group I [n = 125] received 2ml 2% lidocaine before propofol 1% injection. Group II [n = 125] received 50ug/kg ephedrine diluted with 0.9% normal saline in a 2ml solution before propofol 1% injection. Group III [n = 125] unmodified propofol 1% was administered through a 0.22 um filter unit [Millex[r] GS]. Induction of anaesthesia was achieved by 2.5 mg/kg propofol 1% at a rate of 40 mg per 10 seconds as recommended by the manufacturer. An independent blind observer immediately asked the patient to grade the degree of pain experienced on propofol injection on a 4 point verbal rating scale (VRS). The grades of the VRS were no pain, mild, moderate or severe pain. Induction was achieved by iso-flurane 2.5 volume% in 8L oxygen per minute. Three minutes later, an appropriate size of laryngeal mask airway [LMA] was inserted. Heart rate and non invasive mean arterial blood pressure were recorded as follows before induction of anaesthesia [baseline], 1 and 3 minutes after propofol injection and then at 1,3,5 and 10 minutes after LMA placement
Results: overall 28.8% of patients in group III experienced pain on injection of propofol compared to 46.4% in group I and 44% in group II [P< 0.05]. One patient [0.8%] complained of severe pain on injection of propofol in group III compared to 8.8% of patients in group I and 6.4% in group II [P < 0.05]. The decrease in the heart rate and mean arterial blood pressure was significantly less in group II compared to group I and III at 1 and 3 minutes after propofol injection and at 1 and 3 minutes after LMA placement
Conclusion: A microbiological filter provides a non-pharmacological alternative to lidocaine-propofol mixture for reducing the incidence and intensity of propofol-induced pain. Pretreatment with a small dose of ephedrine [50microg/kg] does not reduce the heart rate or mean arterial blood pressure after injection of propofol