Optimizing sedation following major vascular surgery: a double-blind study of midazolam administered by continuous infusion

A randomized, double-blind study was undertaken to determine the dose requirements, recovery characteristics, and pharmacokinetic variables of midazolam given by continuous infusion for sedation in patients following abdominal aortic surgery. Thirty subjects, 50–75 yr, scheduled to undergo aortic reconstructive surgery, entered the study. Following a nitrous oxide-isoflurane-opioid anaesthetic technique, patients were randomly allocated to receive one of three loading doses (0.03, 0.06 or 0.1 mg · kg^?1) and initial infusion rates (0.5, 1.0 or 1.5 μg · kg^?1 · min^?1) of midazolam, corresponding to groups low (L), moderate (M) and high (H). The infusion of midazolam was adjusted to maintain sedation levels of “3, 4 or 5,“ which permitted eye opening in response to either verbal command or a light shoulder tap, using a seven-point scale ranging from “0” (awake, agitated) to “6” (asleep, non-responsive). Additionally, morphine was given in increments of 2.0 mg iv prn for analgesia. On the morning after surgery, midazolam was discontinued, and the tracheas were extubated when patients were awake. Blood samples were taken during, and at increasing intervals for 48 hr following discontinuation of the infusion, and analyzed by gas chromatography. The desired level of sedation was maintained during more than 94% of the infusion period in all three groups, with a maximum of three dose adjustments per patient, for treatment which lasted 16.3 ± 0.6 hr. There was, however, an increase in both the infusion rates and mean plasma concentrations from Group L to Group H (P < 0.05), which corresponded to an inverse relationship of morphine requirements during the period of sedation (P < 0.05, Group H vs Group L). Optimal midazolam infusion rates and resulting plasma concentrations at the times the infusions were discontinued (in parentheses) were as follows — Group L: 0.60 ± 0.18 μg · kg^?1 min^?1 (76 ± 32 ng · mL^?1), Group M: 0.90 ± 0.52 μg · kg^?1 · min^?1 (133 ± 71 ng · mL^?1), and Group H: 1.34 ± 0.69 μg · kg^?1 · min^?1 (206 ± 106 ng · mL^?1). Times to awakening were longer in Group H: 3.1 ± 3.4 hr, than in Group L: 1.1 ± 0.8 h, P < 0.05. Pharmacokinetic variables were found to be dose- independent over the range of infusion rates. Mean values were t_1/2β = 4.4 ± 1.5 hr, CL = 5.94 ± 1.69 mL · min^?1 · kg^?1, Vd = 3.13 ± 1.07 L · kg^?1. It is concluded that midazolam, infused between 0.6–0.9 μg · kg^?1 · min^?1, provides a stable level of sedation, when administered in conjunction with intermittent iv morphine following AAS. This sedation technique, which costs $1.65 ± 0.73 hr^?1 ($Can), is associated with rapid recovery and minimal side effects.     

RETRACTED ARTICLE: Optimal anti-emetic dose of granisetron for preventing post-operative nausea and vomiting

In order to determine the optimal effective dose of granisetron for preventing postoperative nausea and vomiting, the drug was administered in doses of either 20, 40 or 60 μg sd kg^?1. The efficacy of granisetron was evaluated in a randomized, double-blind comparison with placebo in 100 patients undergoing general anaesthesia for major gynaecological surgery. The patients received a single dose of either granisetron or placebo (saline) iv immediately after recovery from anaesthesia. The effects were assessed during the 24 hr after recovery from anaesthesia by means of a nausea and vomiting score; 0 = no emetic symptoms, 1 = nausea, 2 = vomiting. The treatment groups were similar for patient characteristics, surgical procedures and anaesthetics administered. The mean scores were 0.7, 0.6, 0.2 and 0.2 after administration of placebo, granisetron 20, 40 and 60 μg · kg^?1, respectively. Granisetron 40 μg · kg^?1 was as effective as 60 μg · kg^?1 and both resulted in reduction of the scores compared with placebo and granisetron 20 μg · kg^?1 (P < 0.05). In conclusion, granisetron 40 μg · kg^?1 is considered to be the appropriate dosage for preventing postoperative emesis after anaesthesia.     

Oral midazolam premedication for children with congenital cyanotic heart disease under-going cardiac surgery: a comparative study

To determine whether oral midazolam is a safe and effective alternative to our current standard premedication for children with cyanotic congenital heart disease (CCHD), 30 children aged 1–6 yr, scheduled for elective cardiac surgery, were studied. The children were randomly assigned to one of two groups: Group I received oral midazolam 0.75 mg · kg^{? 1} 30 min before separation from their parents in the surgical waiting area, and Group II received oral or rectal pentobarbitone 2 mg · kg^{? 1} at 90 min, and morphine 0.2 mg· kg^{? 1} and atropine 0.02 mg· kg^{? 1} im at 60 min before separation. Heart rate, haemoglobin oxygen saturation (SpO₂) and anxiolysis and sedation scores were recorded at four times during the study: at baseline (immediately before premedication), immediately after administration of the premedication, at separation of children from parents in the waiting area and at the time of application of the face mask in the operating room. We found that in Group I, anxiolysis improved at separation from parents compared with baseline (P < 0.05) and sedation increased both at separation and on mask application (P < 0.05), whereas in Group II anxiolysis did not change at any time and sedation increased only at separation (P < 0.05). Intramuscular injection of morphine produced a transient decrease in mean SpO₂ (from 84% to 76%) (P < 0.05) that did not occur after ingestion of oral midazolam. The results of this study indicate that oral midazolam is a safe and effective replacement for the standard premedication for children with CCHD undergoing cardiac surgery and avoids the decrease in SpO₂ associated with im injections.     

The pharmacodynamics and pharmacokinetics of Org 9426, a new non-depolarizing neuromuscular blocking agent,in patients anaesthetized with nitrous oxide,halothane and fentanyl

The pharmacodynamics and pharmacokinetics of a new non-depolarizing neuromuscular blocking agent, Org 9426, were investigated. Ten patients undergoing elective head and neck surgery and anaesthetized with nitrous oxide, halothane and fentanyl, received a bolus dose of Org 9426 (I mg · kg^?1, 3 × ED₉₀). The isometric contractions of the adductor pollids muscle following ulnar nerve stimulation (0.1 Hz and intermittent TOF) were measured. Blood and urine were sampled over 8 and 24 hr, respectively. Concentrations of Org 9426 and its possible metabolites in plasma and urine were determined using HPLC. Pharmacokinelic variables were calculated by iterative linear least square regression analysis. Intubation conditions were excellent one minute after administration at a neuro-muscular block of 88 (13)% (Mean (CV)). Onset time until maximum block, duration until 25% recovery of twitch height, and recovery from 25 until 75% of twitch height were 1.7 (32), 53 (19) and 20 (37) min, respectively. The TOF reached a ratio of 0.7 after 87 (19) min. Half lives were 1.8(33), 19(34), 131 (62) min, respectively, in a three exponential decay; distribution volume at steady-state and plasma clearance were 0.264 (56) L · kg^{? 1} and 4.0 (21) ml · kg^{? 1} · min_{? 1}, respectively. Plasma concentration at 25% recover)1 of the twitch height was 1.0 mg · L^{? 1}. Within 24 h, 33 (37)% of Org 9426 was excreted unchanged in the urine. Metabolites were absent both in plasma and urine. We conclude that the difference in potency between Org 9426 and vecuronium is similar to the difference between their effective concentrations. Org 9426 mimics vecuronium in its time-course of action and pharmacokinetic behaviour and produces excellent intubaling conditions one minute following the administration of I mg · kg^{? 1}.     

Upper airway obstruction during midazolam sedation: modification by nasal CPAP

We examined the depressant effect of midazolam on respiration in 21 healthy women undergoing lower abdominal surgery with spinal anaesthesia. Airway gas flow, airway pressure, and the sound of snoring were recorded together with arterial oxygen saturation (SpO₂. After spinal anaesthesia was established, subjects were deeply sedated with pentazocine 15 mg followed by incremental doses of midazolam 1 mg iv up to 0.1 mg · kg^?1. When SpO₂ decreased to < 90% or snoring and/or apnoea was observed, continuous positive airway pressure applied through the nose (nasal CPAP) was increased until the respiratory deterioration was reversed. While one patient remained free of respiratory events, the other 20 patients were successfully treated with nasal CPAP restoring normal SpO₂ (95.5 ± 1.7%) without snoring. Stepwise reduction of nasal CPAP determined the minimally effective CPAP to prevent snoring to be 5.1 ±2.1 cm H₂O. Further reduction of nasal CPAP induced snoring in 15 patients and obstructive apnoea in five patients with the latter accompanied by a severe reduction of SpO₂ (87.4 ± 6.1%). Patients with apnoea were older than those who snored (P < 0.05). We conclude that upper airway obstruction contributes considerably to decreases in SpO₂ during midazolam sedation for spinal anaesthesia.     

Preoperative anxiety: detection and contributing factors

The purpose of this study was to determine whether there is a correlation between anxiety the night before surgery and that existing immediately preoperatively, whether anaesthetists can detect preoperative anxiety and to establish the presence of any factors that might assist in the determination of preoperative anxiety. Anxiety was measured objectively using the Spielberger State-Trait Anxiety Inventory (STAI), and the Multiple Affect Adjective Check List (MAACL). Anxiety was found to be higher infemales and those not having had a previous anaesthetic, and to remain constant from the afternoon before surgery to the immediate preoperative period. Anaesthetists were found to be poor assessors of anxiety unless they specifically questioned their patients about this.     

Midazolam coinduction does not delay discharge after very brief propofol anaesthesia

Previous reports have demonstrated synergism of midazolam and propofol for induction of anaesthesia in humans. We tested the hypothesis that in the presence of alfentanil, the combination of midazolam with propofol for a very brief operative procedure would not affect the recovery phase. During pre-oxygenation, 64 outpatients scheduled for dilatation and curettage received placebo, or low-dose midazolam (0.03 mg · kg^?1), or high-dose midazolam (0.06 mg · kg^?1) iv, in a randomized double-blind manner. They then received alfentanil 10 μg · kg^?1 iv, followed by titrated doses of propofol iv for induction and maintenance of anaesthesia. Ventilation with 70% N₂O in O₂ by mask was controlled to achieve a PETCO₂ 30–40 mmHg. Outcome measures were: propofol dose (induction and maintenance), time until eye-opening to command, and time to discharge-readiness. Propofol induction dose was decreased by increasing doses of midazolam (P = 0.00005). Midazolam delayed time to eye-opening (P = 0.02) but not time to discharge-readiness. This study had an 80% power to detect a 39 min difference in time to discharge-readiness. We conclude that midazolam propofol co-induction in the presence of alfentanil delays eye-opening, but does not delay discharge after anaesthesia.     

Anaesthetic management of acute blunt thoracic trauma

Sunnybrook Health Science Centre is an adult regional trauma unit serving metropolitan Toronto and environs. We undertook a nvo-year retrospective review of patients admitted to our institution with blunt thoracic trauma. Three hundred and thirty-three patients with blunt trauma and an injury severity score (ISS) greater than 17 required emergency surgery. Of these, 208 had blunt thoracic injuries while 125 did not have chest injuries. Both groups were similar with respect to age but patients with thoracic trauma had a greater ISS. (P < 0.05) and greater intraoperative mortality (P < 0.01). The aetiology of the intraoperative deaths with one exception was exsanguination. Emergency thoracotomy or sternotomy indicated a poor prognosis with a mortality rate of 80%. The most common intraoperative problem was an elevated airway pressure. Awake intubation was undertaken in 77.5% of patients requiring anaesthesia and surgery because of the potentially compromised airways and difficult intubations due to the nature of the associated injuries. Finally, 74% of patients undergoing urgent surgery required mechanical postoperative ventilation. The presence of blunt chest trauma should be considered a marker of the severity of injury sustained by the patient.     

Propofol or midazolam for short-term alterations in sedation

It is often necessary to adjust a patient’s sedation level while they are in the intensive care unit. The purpose of this study was to compare propofol with midazolam for controlling short-term alterations in sedation. Twenty-three patients undergoing an interactive procedure, physiotherapy, during mechanical ventilation of the lungs were studied. The patients were randomly assigned to receive infusions of propofol or midazolam for sedation. Sedation was assessed using the method of Ramsay, where 3 is drowsy responding only to commands; and 5 is asleep with a slow response to light glabellar tap. Prior to physiotherapy sedation was deepened from 3 to 5 by increasing the sedative infusion rate, and level 5 was maintained during physiotherapy by adjusting the infusion rate whenever necessary. After physiotherapy, the sedative dose was reduced until level 3 was again achieved. During physiotherapy, sedation level 5 was achieved for 53.9% of the time with propofol but for only 25.7% with midazolam (P < 0.01). After physiotherapy, those patients sedated with propofol re-awakened to level 3 faster (8.3 ± 2.3 min, mean ±SE) than those receiving midazolam (92.8 ± 35.0 min, P < 0.05). After physiotherapy, a further 1.8 ± 0.5 dose adjustments were required to the midazolam infusion while only 0.4 ± 0.2 adjustments were required to the propofol infusion (P < 0.05). During physiotherapy 3.0 ± 0.5 dose adjustments to the propofol dose were required compared with 3.6 ± 0.5 adjustments to the midazolam dose (NS). It is concluded that, during a standardized stimulus, physiotherapy, propofol infusion allowed a desired sedation score to be maintained for more of the time than did infusion of midazolam. Subsequently, when the infusion rates were reduced, less time was taken to re-awaken to baseline levels after physiotherapy, with fewer adjustments to the infusion rate, in those patients receiving propofol than midazolam.     

Anaesthesia for coronary artery bypass surgery supplemented with subarachnoid bupivacaine and morphine: a report of 18 cases

We report our experience, with general anaesthesia (GA) supplemented with subarachnoid bupivacaine and morphine for coronary artery bypass surgery (CABG) in 18 patients. Fifteen patients were male, and mean age was 62 yr. Anaesthesia (GA) was induced with alfentanil 97 ± 22 μg · kg^{? 1} and midazolam 0.04 ± 0.02 mg · kg^{? 1} supplemented with a muscle relaxant, and maintained with isoflurane (0.25–0.5%) in oxygen throughout surgery. Spinal anaesthesia (SA) was then performed at a lumber level using hyperbaric bupivacaine (23–30 mg) and/ or lidocaine (150 mg) with morphine (0.5–1 mg). Pooled data showed the following haemodynamic results (P < 0.05). Induction of GA produced a decrease in mean arterial pressure (MAP). Addition of SA produced a decrease in heart rate. Heart rate and MAP did not change with sternotomy. Phenylephrine support of arterial blood pressure was used at some time during operation in 17 patients. Supplementation of GA was minimal. Patients received 2.7 ± 0.7 coronary grafts. Operating room time was 3.9 ± 0.6 hr. Postoperative analgesic requirements were minimal, and in half of the patients tracheal extubation occurred on the day of surgery. Complications included one myocardial infarction, one resternotomy, a metabolic encephalopathy in a dialysis- dependent patient, and one case of herpes labialis. No patient recalled intraoperative events. Combined GA with SA may be an effective technique for CABG surgery. Further study of the cardiovascular, neurological and metabolic effects of the technique is required.     

Premedication of children with oral midazolam

In a randomized, double-blind, placebo-controlled study, the safety, efficacy and feasibility of oral midazolam premedication in children were evaluated in an ambulatory surgery unit. Eighty unmedicated children (ASA PS I or II, ages 1-6 yr) were randomly assigned to one of four groups receiving midazolam 0.5, 0.75, or 1.0 mg.kg-1 or a placebo 30 min before separation from parents. Heart rate, systolic blood pressure, arterial oxygen saturation, respiratory rate, sedation and anxiolysis scores were recorded before premedication, every five minutes for 30 min and then during induction of anaesthesia and recovery. We found that heart rate, systolic blood pressure, arterial oxygen saturation and respiratory rate were unchanged during the study. Sedation and anxiolysis scores in the midazolam-treated groups were greater than those in the placebo group and that anxiolysis at the time of separation from the parents was judged excellent in 80-90% of the children who received midazolam. However, sedation and anxiolysis did not differ among the three midazolam groups. Mean times to discharge from hospital were similar for all four groups. The side effects, loss of balance and head control, blurred vision and dysphoric reactions were observed only in the 0.75 and 1.0 mg.kg-1 midazolam groups. We conclude that oral midazolam 0.5 mg.kg-1 is a safe and effective premedication and that 0.75 and 1 mg.kg-1 while offering no additional benefit, may cause more side effects.     

Intrathecal meperidine for elective Caesarean section: a comparison with lidocaine

The purpose of this study was to determine the efficacy of intrathecal meperidine in patients undergoing Caesarean section, and also to compare meperidine with heavy lidocaine. Fifty fall-term pregnant women, ASA physical status I or II, presenting for elective Caesarean section under spinal anaesthesia were randomly divided into two groups with 25 in each, to receive either intrathecal meperidine or lidocaine. All patients received premedication with oral ranitidine, 150 mg, the night before surgery, and again two hours before surgery. Patients in the meperidine group were also given metoclopramide iv 10 mg one hour before surgery. After iv 20 ml·kg^?1 Ringer’s lactate, patients were given either 5% meperidine 1 mg · kg^?1 or 5% heavy lidocaine 1.2 to 1.4 ml intrathecally. The sensory and motor blockades in all except two patients in each group who required sedation at the time of skin incision were adequate for surgery. None of the mothers suffered from any major side effects. The incidence of hypotension was higher in the lidocaine group than in meperidine group (P < 0.05). Pruritus and drowsiness were more common in meperidine group than in lidocaine group (P < 0.01). All the newborns in both groups cried immediately after birth and had an Apgar scope > 7. The mean duration of postoperative analgesia was six hours in the meperidine group and one hour in the lidocaine group (P < 0.01). Postoperative analgesia requirement was less in the meperidine than in the lidocaine group (P < 0.01). It is concluded that intrathecal 5% meperidine in a dose of 1 mg·kg^?1 is superior to 5% heavy lidocaine because of the prolonged postoperative analgesia. The commercial 5% solution of meperidine can be used, without addition, for this purpose.     

Propofol anaesthesia in paediatric ambulatory patients: a comparison with thiopentone and halothane

The purpose of this study was to evaluate the haemodynamic changes during induction, as well as the speed and quality of recovery when propofol (vs thiopentone and/or halothane) was used for induction and maintenance of anaesthesia in paediatric outpatients. One hundred unmedicated children, 3–12-yr-old, scheduled for ambulatory surgery were studied. The most common surgical procedures performed were eye muscle surgery (42%), plastic surgery (21%), dental restoration (15%), and urological procedures (15%). The children were randomized to an anaesthetic regimen for induction/maintenance as follows: propofol/propofol infusion; propofol/halothane; thiopentone/halothane; halothane for both induction and maintenance. Succinylcholine 1.5 mg · kg^?1 was used to facilitate tracheal intubation and N₂O/O₂ were used as the carrier gases in each case. All maintenance drugs were titrated according to the clinical response of the patient to prevent movement and/or maintain BP ± 20% of baseline. Two patients (4%) who received propofol expressed discomfort during injection. The mean propofol dose required to prevent movement was 267 ± 83 μg · kg^?1 · min^?1. The overall pattern of haemodynamic changes, as well as awakening (extubation) times were not different among the four groups. Children who received propofol recovered faster (22 vs 29–36 min) (P < 0.05), were discharged home sooner (101 vs 127–144 min) (P < 0.05), and had less postoperative vomiting (4 vs 24–48%) (P < 0.05) than all others. There were no serious complications or adverse postoperative sequelae in any of the patients in the study. It is concluded that induction and maintenance of anaesthesia with propofol is a well-tolerated anaesthetic technique in children, and is associated with faster recovery and discharged as well as less vomiting than when halothane is used.     

Oral ondansetron decreases vomiting after tonsillectomy in children

Vomiting is a common, unpleasant aftermath of tonsillectomy in children. Intraoperative intravenous ondansetron (OND) reduces vomiting after this operation. Our doubleblind, placebocontrolled, randomized investigation studied the effect of the oral form of OND on vomiting after outpatient tonsillectomy in children. We studied 233 healthy children age 2–14 yr undergoing elective tonsillectomy. Subjects were given placebo (PLAC) or OND 0.1 mg · kg^?1 rounded off to the nearest 2 mg one hr before surgery. Anaesthesia was induced with either propofol or halothane/N₂O. Vecuronium 0.1 mg · kg^?1 was administered at the discretion of the anaesthetist. Anaesthesia was maintained with halothane/N₂O, 50 μg · kg^?1 midazolam iv and 1–1.5 mg · kg^?1 codeine im. At the end of surgery, residual neuromuscular blockade was reversed with neostigmine and atropine. All episodes of inhospital emesis were recorded by nursing staff. Rescue antiemetics in the hospital were 1 mg · kg^?1 dimenhydrinate ivfor vomiting × 2 and 50 μg · kg^?1 droperidol iv for vomiting × 4. Parents kept a diary of emesis after discharge. Postoperative pain was treated with morphine, codeine and/or acetaminophen. The two groups were similar with respect to demographic data, induction technique and anaesthesia time. Oral OND (n = 109) reduced postoperative emesis from 54% to 39%, P < 0.05. This effect was most dramatic inhospital, where 10% of the OND-patients and 30% of the PLAC-group vomited, P < 0.05. The OND-subjects required fewer rescue antiemetics, 7% vs 17%, P < 0.05. In conclusion, oral ondansetron decreased the incidence of vomiting after outpatient tonsillectomy in children.     

Oral clonidine premedication reduces vomiting in children after strabismus surgery

This is a prospective randomized double-blind trial conducted to determine whether preoperative orally administered clonidine causes or potentiates postoperative vomiting in 140 children (3–12 yr) undergoing strabismus surgery. They were all inpatients and classified randomly into four groups (n = 35 each); placebo (control), diazepam 0.4 mg · kg^?1, clonidine 2 μg · kg^?1, and clonidine 4 μg · kg^?1. These agents were administered 93–112 min (mean: 100 min) before the anticipated time of induction of anaesthesia. All children received inhalational anaesthesia with halothane and nitrous oxide in oxygen.’ Muscle relaxation in all patients was obtained with vecuronium and residual neuromuscular blockade was antagonized with neostigmine and atropine before tracheal extubation. Diclofenac suppository was prescribed to prevent postoperative pain. No opioids or postoperative antiemetics were administered. All children remained in hospital for two days postoperatively. The incidence and frequency of vomiting were compared in the groups with Kruskall-Wallis Rank test. Clonidine 4 μg · kg^?1 caused a lower incidence and frequency of vomiting than did placebo and diazepam (incidence and frequency: 11% and 1,37% and 3, and 34% and 2 in clonidine 4 μg · kg^?1, placebo, and diazepam, respectively; P < 0.05 for clonidine 4 μg · kg^?1 vs placebo and diazepam). However, lowdose clonidine was ineffective. These data suggest that preanaesthetic medication with clonidine 4 μg · kg^?1 may be useful for preventing emesis following strabismus surgery. This property of clonidine indicates that it may be superior to other sedative premedicants such as diazepam and midazolam.     

Oral midazolam premedication in children: the minimum time interval for separation from parents

To determine the minimum time interval between oral midazolam (0.5 mg· kg^?1) premedication and separation from parents that ensures a smooth separation, 30 children were assigned randomly to one of three groups (ten children per group). The groups differed only in the time interval between administration of midazolam and separation from their parents: 10, 20 or 30 min. Heart rate, systolic blood pressure, and sedation and anxiolysis scores were assessed before midazolam premedication (baseline), at the time of separation from parents, and during the application of a face mask at the induction of anaesthesia. We found that heart rate and systolic blood pressure changes were similar for all three groups throughout the study period. Sedation scores at the time of separation from parents and on application of the mask for all three groups were greater than baseline values. Sedation scores at separation did not differ among the three groups. Anxiolysis values did not differ from baseline values at any time for all three groups. We conclude that children may be separated from their parents as early as ten minutes after receiving oral midazolam, 0.5 mg · kg^?1.     

A comparison of morphine-perphenazine and midazolam on preoperative sedation and arterial oxygen saturation

The effectiveness of midazolam and a mixture of morphine-perphenazine premedication to produce sedation and their effects on preoperative oxygen saturation (SaO2) were examined. Eighty-five patients whose SaO2 measured with a pulse oximeter was greater than 90% and who were not receiving narcotic sedatives or oxygen were randomized to three groups. Each patient had his SaO2 recorded before premedication with placebo (saline), midazolam 0.08 mg.kg-1 or morphine 0.15 mg.kg-1 with perphenazine 2.5-5.0 mg im. From 30-90 min later, prior to anaesthesia SaO2 was repeated, and a sedation score was obtained by a blinded observer using a seven point scale. Median sedation scores were greater for midazolam (4) than for morphine-perphenazine (2) and placebo (1) (P less than 0.0001). As well, there was a decrease in the SaO2 in the morphine-perphenazine group (1.7 +/- 2.7%, P less than 0.001) but not in the midazolam and placebo groups (0.1 +/- 2.3%, -0.8 +/- 2.1%). In conclusion midazolam produced greater sedation than morphine-perphenazine and placebo without effect on SaO2 whereas morphine-perphenazine showed a decrease in SaO2 preoperatively.     

Rapid tracheal intubation with atracurium: the timing principle

The “Timing Principle” utilises a single bolus of nondepolarising neuromuscular blocking drug followed by thiopentone given at the onset of clinical weakness. The purpose of this study was to compare the intubating conditions after succinylcholine and after atracurium used according to the “timing principle.” Eighty patients were randomly assigned to four groups of 20. Three study groups were given atracurium 0.5, 0.75 or 1 mg · kg^?1 (Groups I, II and III respectively) and the control group (Group IV) received succinylcholine 1.5 mg · kg^?1. The study groups received fentanyl 1 μg · kg^?1, atracurium three minutes later, followed by thiopentone 4–6 mg · kg^?1 at the onset of ptosis. The control group had a defasciculating dose of atracurium (0.025 mg · kg^?1) and fentanyl (1 μg · kg^?1) followed by thiopentone (4–6 mg · kg^?1) and succinylcholine three minutes later. The trachea was intubated one minute after thiopentone was given. The intubating conditions were then graded by a laryngoscopist who was unaware of the induction sequence. All patients were interviewed on the day after surgery. Intubation scores of patients in Group I were worse than in Groups II, III and IV (P < 0.005) but there were no differences between Groups II, III and IV. The technique was not associated with severe haemodynamic changes. All patients, except one were able to cough well after administration of atracurium, before induction of anaesthesia with thiopentone. Patients were generally satisfied with this method of induction. It is concluded that atracurium, when used according to the timing principle, can be an alternative to succinylcholine during rapid-sequence induction.     

Propofol for pulsed dye laser treatments in paediatric outpatients

Pulsed dye laser is a new treatment for port-wine stains, congenital lesions in the cutaneous vascular plexus. We report our anaesthetic experience with paediatric outpatients treated in the dermatology clinic. From April to November 1993, 48 ASA 1 children were anaesthetised for a total of 105 consecutive laser treatments. The youngest was eight months old, the oldest was 12 yrs old and most of the sessions (43%) were done for children aged from two to four years. Each received acetaminophen (10 mg · kg^?1 po) before treatment. A propofol infusion was chosen for anaesthesia to achieve early discharge and to reduce the incidence of postoperative emesis. The infusion was adjusted to maintain blood pressure within 20% of baseline and to keep the child immobile. The dose was progressively reduced during the procedure from 400 μg · kg^?1 · min^?1 to 100 μg · kg^?1 · min^?1. Fentanyl (2 μg · kg^?1 iv) was added for analgesia. Respiration was spontaneous through a nasopharyngeal airway (air in oxygen 40%). Anaesthesia proceeded uneventfully in all cases and lasted for 15–30 min (63% of treatments), 30–45 min (28%) or 45–60 min (9%) according to the size of the lesion. The mean stay in the recovery room was 25.1 min and none of the patients experienced emesis. Our experience shows that general anaesthesia with propofol supplemented with fentanyl offers a rapid onset and awakening, a painless treatment and an immobile child. It is a safe solution to alleviate pain from repeated painful procedures even in small children under two years of age.     

Nicardipine and verapamil attenuate the pressor response to laryngoscopy and intubation

In a prospective, double-blind study, we compared the efficacy of iv nicardipine hydrochloride and verapamil hydrochloride in attenuating the cardiovascular responses to laryngoscopy and tracheal intubation, in 45 patients undergoing elective surgery with general anaesthesia. Patients were allocated randomly to one of three groups of 15 patients. Patients in Group I received saline while those in Groups II and III received nicardipine hydrochloride, 0.03 mg · kg^{? 1} or verapamil hydrochloride, 0.1 mg · kg^{? 1} iv three minutes before laryngoscopy and intubation. Patients in Group I showed the greatest increase in SBP 25.4 ± 2.2 mmHg and HR 35.7 ± 3.8 beats · min^{? 1} at one minute after intubation (P < 0.001), and these changes persisted throughout the study period albeit with decreasing magnitude. After drug administration, patients in Groups II and III demonstrated increases in HR of 26 ± 2.4 and 15.1 ± 2.2 beats · min^{? 1} and decreases in SBP of 24.8 ± 2.0 and 18.8 ± 2.4 mmHg respectively (P < 0.001). It is concluded that nicardipine and verapamil are effective in attenuating pressor responses to laryngoscopy and intubation but did not control the tachycardia.