Smoking increases the requirement for rocuronium

Purpose

To compare the potency of rocuronium in non-smokers and smokers during general anaesthesia.

Methods

In a randomized, open clinical study, 40 patients, 17–62 yr of age, were anaesthetized with propofol, alfentanil and nitrous oxide in oxygen. After obtaining individual dose-response curves for rocuronium, bolus doses of rocuronium were given to maintain neuromuscular block at 90–99% for 60 min. Evoked adductor pollicis electromyography (EMG) was used to monitor neuromuscular block.

Results

The ED₉₅ values (± SEM) for rocuronium were 460.5 ± 28.9 and 471.5 ± 22.1 μg·kg^?1 for nonsmokers and smokers, respectively (P:NS). However, doses of rocuronium to maintain 90–99% neuromuscular block (± SEM) were 620.1 ± 46.7 and 747.4 ± 56.0 μg·kg^?1·hr^?1 for non-smokers and smokers, respectively (P = 0.0504).

Conclusion

The results may indicate increased metabolism of rocuronium in smokers rather than increased requirement of rocuronium at the receptor site.     

Sevoflurane and isoflurane impair edrophonium reversal of vecuronium-induced neuromuscular block

Purpose

A dose-response relationship study for edrophonium to examine the modification of volatile anaesthetics on reversal of vecuronium block.

Methods

One hundred and twenty ASA (I–II) patients were anaesthetized with sevoflurane, isoflurane (I minimum alveolar anaesthetic concentration [MAC] end-tidal concentration), or fentanyl-diazepam anaesthesia, in combination with 66% nitrous oxide (n = 40 for each group). The evoked electromyogram (EMG) response of the abductor digiti minimi was monitored at 20 sec intervals following train-of-four (TOF) stimulation of the ulnar nerve. The initial neuromuscular block was produced by vecuronium 100 μg · kg^?1. When the amplitude of the first response (T₁) had spontaneously recovered to 10% of the control, edrophonium (0, 125, 400, 700 or 1000 μg · kg^?1; eight patients each) was randomly administered, and the ratio of the fourth TOF to the first response (TOFR ) was monitored at one minute intervals for 10 min.

Results

Sevoflurane and isoflurane impaired the edrophonium-assisted TOFR recovery in an edrophonium dose and time dependent manner. The dose-response curves at 10 min exhibited a greater shift to the right in the sevoflurane and isoflurane groups than in the fentanyl-diazepam-nitrous oxide group (P < 0.05). Higher ED₅₀ values (the edrophonium dose required to obtain TOFR value of 50%) in the sevoflurane (> 1000 μg · kg^?1) and isoflurane groups (851 · μg · kg^?1) were observed than in the fentanyl-diazepam-nitrous oxide group (339 μg · kg^?1) (P < 0.05).

Conclusion

One MAC sevoflurane and isoflurane anaesthesia impair edrophonium reversal of vecuronium block to a similar degree.     

Effect of different anesthetic agents on oculocardiac reflex in pediatric strabismus surgery

Purpose

The oculocardiac reflex (OCR) occurs frequently during pediatric strabismus surgery. The aim of this study was to assess the effects of various anesthetic regimens on the incidence of OCR during the surgery.

Methods

Two hundred and eighty children, 1 to 9 years old, undergoing elective strabismus surgery, were randomly assigned to eight groups; ketamine-sevoflurane (KS), ketamine-desflurane (KD), ketamine-propofol (KP), ketamine-remifentanil (KR), midazolam-sevoflurane (MS), midazolam-desflurane (MD), midazolam-propofol (MP), and midazolam-remifentanil (MR). No premedication was given. Anesthesia was induced using ketamine 1 mg·kg^?1 or midazolam 0.15 mg·kg^?1 with 66% N₂O in O₂. Laryngeal mask airways (LMAs) were placed with rocuronium 0.5 mg·kg^?1. Anesthesia was maintained with sevoflurane 2–3 vol. %, desflurane 5–6 vol. %, propofol 7–8 mg·kg^?1·h^?1, or remifentanil 0.75 µg·kg^?1 over 1 min, followed by a continuous infusion of remifentanil 0.5 µg·kg^?1·min^?1 with 66% N₂O in O₂. Heart rate (HR) was recorded during extraocular muscle (EOM) manipulation. OCR was defined as a reduction in HR of more than 20% induced by the traction of an EOM.

Results

In patients given ketamine, OCR occurred more frequently in the KP (65.7%) and KR (62.9%) groups than in the KD (29.4%) and KS (37.1%) groups (P < 0.05). In patients given midazolam, OCR occurred more frequently in the MP (54.3%) and MR (60.6%) groups than in the MD (36.4%) and MS (31.4%) groups (P < 0.05).

Conclusion

Propofol or remifentanil anesthesia was associated with a higher incidence of OCR during pediatric strabismus surgery than sevoflurane and desflurane anesthesia, when either ketamine or midazolam was used as an induction agent.     

Propofol, but not thiopentone or etomidate, enhances isoflurane-induced coronary vasodilatation in dogs

Purpose

To test the hypothesis that thiopentone, propofol, and etomidate alter the coronary vascular effects of abruptly administered isoflurane.

Methods

Dogs (n = 6) received inspired isoflurane 5% in the presence of thiopentone (20 mg·kg^?1 induction dose and 20 mg·kg^?1·hr^t-1 infusion), propofol (5 mg·kg^?1 induction dose and 40 mg·kg^?1·hr^?1 infusion), etomidate (2 mg·kg^?1 induction dose and 5 mg·kg^?1·hr^?1 infusion), or isoflurane (1.0 MAC) anaesthesia in a random fashion. Haemodynamics were assessed in the conscious state, during baseline anaesthesia, and at 30 sec intervals for five minutes after beginning isoflurane 5%.

Results

Rapidly administered isoflurane caused greater (P < 0.05) reductions in coronary vascular resistance in thiopentoneor propofol-than in isoflurane-anaesthetized dogs. Isoflurane produced greater (P < 0.05) increases in the ratio of coronary blood flow velocity to pressure-work index (an index of myocardial oxygen consumption; +109 ± 19 % during isoflurane alonevs + 182 ± 27 % change from baseline during propofol and isoflurane) consistent with relatively greater direct coronary vasodilatation during baseline propofol than during baseline isoflurane anaesthesia. Isoflurane caused larger increases in coronary blood flow velocity in dogs anaesthetized with etomidate concomitant with higher coronary perfusion pressure and pressure-work index than in those anaesthetized with isoflurane alone.

Conclusions

The results suggest that thiopentone, propofol, and etomidate each uniquely modify the coronary vascular responses to abrupt administration of high inspired concentrations of isoflurane in chronically instrumented dogs.     

Bradycardia produced by pyridostigmine and physostigmine

Purpose

The bradycardia produced by pyridostigmine and physostigmine in an animal model of acute cardiac denervation was examined according to its relation to cholinesterase inhibition and sensitivity to block by cholinergic receptor antagonists.

Methods

Cats were anaesthetised, vagotomised and propranolol-treated. Heart rate was continuously recorded. Erythrocyte cholinesterase activity of arterial blood was measured using a radiometric technique. Nicotinic and muscarinic M₁ receptors were blocked with hexamethonium and pirenzepine, respectively. M₂ receptors were blocked with gallamine, pancuronium and AFDX-116.

Results

With pyridostigmine and physostigmine, the dose-response relationship for the decrease in heart rate (ED₅₀ 1.05 ± 0.25 and 0.198 ± 0.03 mg·kg^?1, respectively) was shifted to the right of that for the inhibition of cholinesterase activity (ED₅₀ 0.094 ± 0.03 and 0.032 ± 0.01 mg·kg^?1, respectively). The decrease in cholinesterase activity reached a plateau at a cumulative dose of 0.56 ± 0.08 and 0.32 ± 0.08 mg·kg^?1, respectively. In contrast, there did not appear to be a plateau in the bradycardic effect. The bradycardia produced by pyndostigmine and physostigmine was blocked by hexamethonium (ED₅₀ 10 ± 1.3 and 15.3 ± 2.4 mg·kg^?1, respectively), pirenzepine (ED₅₀ 68 ± 16 and 138 ± 32 μg·kg^?1. respectively), gallamine (56 ± 11 and 67 ± 17 μg·kg^?1, respectively ), pancuronium (32 ± 10 and 30 ± 4 μg·kg^?1, respectively), and AFDX-116 (31 ± 4 and 28 ± 4 μg·kg^?1, respectively).

Conclusion

The bradycardia produced by reversible anticholinesterase drugs containing a carbamyl group is not dearly related to the degree of cholinesterase activity, and has a low sensitivity to nicotinic and muscannic M₁ and a high sensitivity to muscarinic M₂ receptor antagonists.     

Prolonged mivacurium infusion in young and elderly adults

Purpose

This study was designed to evaluate phanmacodynamically and phamnacokinetically if the cis-cis isomer of mivacurium contributed to neuromuscular block during prolonged infusions lasting more than four hours in young adult and elderly (> 60 yr) patients.

Methods

The mechanomyogramic neuromuscular response of the adductor pollicis was recorded in 32 adults 18–59 yr. and 19 elderly (> 60 yr.) patients dunng N₂O:O₂:opioid anaesthesia. The mivacurium infusion rate was adjusted to maintain single twitch depression at 95 ± 4% of control. Blood samples were taken every 30 min to determine the plasma concentration of cis-cis isomer of mivacurium. At the end of the surgical procedure, patients were allowed to recover spontaneously to at least 25% of control twitch response.

Results

The mean mivacurium infusion requirement to maintain 97 ± 1 (mean ± SD)% depression of the twitch response was 6.0 ± 0.4 μg· kg^?1· min^?1 in young adults, and 4.3 ± 0.3 μg· kg^?1· min^?1 in elderly patients (P < 0.001). The infusion requirement in patients with low plasma cholinesterase activity was the lowest 2.4 ± 1.2 μg· kg^?1· min^?1. Plasma cis-cis isomer concentrations reached peak levels within one-two hours and remained relatively constant throughout the duration of infusion even in patients with tow cholinesterase activity. There was no relationship between duration of infusion, plasma concentrations of cis-cis isomer and the early recovery indices of mivacurium (up to 25%). Neuromuscular transmission recovered adequately with or without antagonism in all patients.

Conclusion

When the mivacurium infusion was titrated to maintain 95 ± 4% twitch depression, the plasma concentration of the cis-cis isomer did not increase during prolonged infusions (four hours) and neuromuscular transmission recovers satisfactorily.     

Preoperative ketorolac increases bleeding after tonsillectomy in children

Purpose

To compare the incidence of vomiting following codeine or ketorolac for tonsillectomy in children.

Methods

We had planned to enrol 240 patients, aged 2–12 yr undergoing elective tonsillectomy into a randomized, single-blind study in University Children’s Hospital. The study was terminated, after 64 patients because interim analysis of the data by a blinded non-study scientist concluded that the patients were at undue risk of excessive perioperative bleeding. After induction of anaesthesia by inhalation with N₂O/halothane or with propofol 2.5?3.5 mg· kg^?1 iv, the children were administered 150 μg· kg^?1 ondansetron and 50 μg · kg^?1 midazolam. Maintenance of anaesthesia was with N₂O and halothane in O₂. Subjects were administered either 1.5 mg · kg^?1 codeine im or 1 mg· kg^?1 ketorolac iv before the commencement of surgery. Intraoperative blood loss was measured with a Baxter Medi-Vac® Universal Critical Measurement Unit. Postoperative management of vomiting and pain was standardized. Vomiting was recorded for 24 hr after anaesthesia. Data were compared with ANOVA, Chi-Square analysis and Fisher Exact Test.

Results

Thirty-five subjects received ketorolac. Demographic data were similar. The incidence of vomiting during the postoperative period was 31% in the codeine-group and 40% in the ketorolac-group. Intraoperative blood losses was 1.3 ± 0.8 ml · kg^?1 after codeine and 2.2 ± 1.9 ml · kg^?1 after ketorolac (mean ± SD) P < 0.05. Five ketorolac-treated patients had bleeding which led to unscheduled admission to hospital, P < 0.05, Exact Test.

Conclusion

Preoperative ketorolac increases perioperative bleeding among children undergoing tonsillectomy without beneficial effects.     

40 Hz Auditory steady-state response and EEG spectral edge frequency during sufentanil anaesthesia

Purpose

The auditory steady-state evoked response (ASSR) is an evoked potential which provides a sensitive measure of the effects of general anaesthetics on the brain. We used pharmacokinetic-pharmacodynamic (PK-PD) modelling to compare the effects of sufentanil on the amplitude of the ASSR with its effect on spectral edge frequency (SEF) of the electroencephalogram.

Methods

Nine patients scheduled for elective cardiac surgery participated. Midazolam (70 μg·kg^?1 im) was given 60 min before entering the operating room. Anaesthesia was induced with 5 μg·kg^?1 sufentanil at a rate of 0.83 μg·kg^?1·min^?1. The ASSR, SEF and plasma sufentanil concentrations were measured for 30 min ater induction of anaesthesia before surgery. The half-life between the central and effect site compartments (t_1/2K_eo), the 50% inhibitory concentration (IC₅₀) and the slope factor (gamma) were computed.

Results

The amplitude of the ASSR increased during the first three minutes of infusion of sufentanil by up to 40%. This was followed by a rapid decrease between the fourth and fifth minutes to 16% of baseline. The SEF decreased progressively during the first five minutes of infusion to 18% of baseline. Both measures subsequently showed modest recovery. The parameters gamma, IC₅₀ and t_1/2K_eofor ASSR were (mean ±SD) 6,0 ±3.7, 2.1 ±1,2 ng·ml^?1 and 7.3 ±2.4 min. For SEF the values were 5.9 ±5.2, 1.4 ±0.7 ng·ml^?1 (P < 0.05 compared with ASSR) and 6.8 ±2,4 min.

Conclusion

The sensitivity of ASSR to sufentanil is less than that of the SEF.     

Pharmacokinetics of doxacurium during normothermic and hypothermic cardiopulmonary bypass surgery

Purpose

To compare the pharmacokinetic behaviour of doxacurium in patients undergoing normothermic or hypothermic cardiopulmonary bypass (CPB) for coronary artery bypass graft surgery.

Methods

Twenty patients in two equal groups were studied. Anaesthesia was induced with sufentanil and midazolam after a standard premedication. Doxacurium was administered at 3 × ED₉₅ (80μ·kg^?1), and anaesthesia was maintained with 0.5 μg·kg^?1 hr^?1 sufentanil, 0.05 mg·kg^?1 midazolam and isoflurane 0.5–1%. Systemic temperature for patients in the normothermic and hypothermic groups was maintained at 33–36C and 26–30C respectively. Timed blood and urine samples were collected and pharmacokinetic parameters were estimated using a non-compartmental approach.

Results

For the normothermic and hypothermie groups, terminal elimination half-life (t_1/2B) was 100.1 ± 28 and 183.8 ± 60 min (P < 0.05) respectively, elimination half-life during the CPB phase (T_1/2 CPB) 114.5 ± 10 and 183.8 ± 60 min (P < 0.05), mean residence time 108.8 ± 25 and 164.8 ± 34 min (P < 0.05) and apparent volume of distribution at steady state 0.20 ± 0.03 and 0.26 ± 0.04 L·kg^?1 (P < 0.05). Compared with the hypothermie group, the normothermic group had a higher rate of renal clearance (1.40 ± 0.4 vs 0.93 ± 0.3 ml·min^?1·kg^?1;P < 0.05) and a higher value for renal clearance as a percentage of the total clearance (76.2 ± 10 vs 58.3 ± 20%).

Conclusion

The elimination rate of doxacurium during normothermic CPB is faster than that in hypothermic CPB.     

Comparison of nifedipine and metoprolol on collateral coronary blood flow in a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia

Purpose

This study compared the effects of nifedipine and metoprolol on collateral-dependent myocardial blood flow in a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia.

Methods

Collateral coronary circulation was induced in 15 three-week-old piglets by banding of the proximal left anterior descending coronary artery (LAD). After 8–10 wk, the distal LAD was ligcted and the open-chest pigs were randomized to receive infusions of either saline, nifedipine (5 μg·kg^?1 · min^?1) or metoprolol (10 μg · kg^?1 · min^?1) for 30 min during isoflurane anaesthesia (2%). Transient ischaemia was induced by 30 secocclusion of the left circumflex artery. Arterial blood pressures, heart rate and regional myocardial blood flow (radio-labelled microspheres technique) were measured at the end of drug infusion (baseline) and one minute after transient ischaemia.

Results

No differences in the blood flow to the collateral-dependent (CD) myocardium or haemodynamic variables were observed at baseline among the three groups. Following transient ischaemia, in the nifedipine but not in the metoprolol group, blood flow to the CD myocardium was reduced by 28 ± 24% in the epicardium (P< 0.05) and 56 ± 20% in the endocardium (P< 0.01), resulting from intercoronary and transmural steal. This was associated with a moderate increase (10%, P< 0.05) in the heart rate in the nifedipine group.

Conclusions

In a swine model of chronic coronary obstruction and acute ischaemia during isoflurane anaesthesia, the collateral coronary blood flow was maintained in the presence of metoprolol, but reduced in the presence of nifedipine following transient ischaemia due to intercoronary and transmural steal.     

RETRACTED ARTICLE: Effective dose of granisetron for preventing postoperative emesis in children

Purpose

This study was to identify the minimum effective dose of granisetron, a selective 5-hydroxytryptamine type 3 receptor antagonist, to prevent postoperative vomiting in children who have undergone strabismus repair, tonsillectomy or tonsillectomy with adenoidectomy.

Methods

In a randomized, double-blind fashion, 80 healthy children aged 4–10 yr were assigned to receive either placebo (saline) or granisetron in a dose of 20, 40 or 80 μg· kg^?1 iv immediately following the induction of anaesthesia. All subjects received a standardized anaesthetic, which consisted of sevoflurane in nitrous oxide and oxygen. Rescue antiemetics were administered if two or more episodes of vomiting occurred. Postoperative pain was treated with acetaminophene pr or pentazocine iv. During the first 24 hr after anaesthesia, the frequencies of retching and vomiting were recorded in a standardized fashion by nursing staff while subjects were in a hospital.

Results

There were no differences among four treatment groups with regard to subject characteristics, surgical procedures, anaesthetic and postoperative management or adverse effects. The frequencies of these symptoms were as follows: 65%, 60%, 20% and 15% after administration of placebo, granisetron 20, 40 or 80 μg· kg^?1. Three children who had received either placebo or granisetron 20 μg · kg^?1 required another rescue antiemetic drug, whereas none who had received granisetron 40 or 80 μg · kg^?1 needed rescue drugs.

Conclusion

Granisetron 40 μg · kg^?1 is an effective antiemetic for preventing retching and vomiting following strabismus repair and tonsillectomy in children. Increasing the dose to 80 μg ·kg ^?1 provided no demonstrable benefit in reducing postoperative emesis.     

Remifentanil-Propofol- Anästhesie bei Bandscheibenoperationen: ein Vergleich mit einer Desfluran-N2O- Inhalationsanästhesie Effekte auf Hämodynamik und Aufwachverhalten

Zusammenfassung Fragestellung: Unterscheidet sich eine totale intraven?se An?sthesie mit Propofol (P) und Remifentanil (R) von einer Inhalationsan?sthesie mit Desfluran (D) und Lachgas (L) bei lumbalen Bandscheibenoperationen hinsichtlich der Steuerbarkeit der Narkose, der Beeinflussung h?modynamischer Parameter, des Aufwachverhaltens und des postoperativen Analgetikabedarfs der Patienten? Methodik: 50 Patienten (ASA I–II, 18–65 Jahre) wurden randomisiert entweder einer P/R- oder D/L-Gruppe zugeteilt. Nach standardisierter Narkoseeinleitung (1 μg/kg Remifentanil, 1,5 mg/kg Propofol, 0,1 mg/kg Cisatracurium) wurde die An?sthesie in der D/L-Gruppe bedarfsadaptiert mit Desfluran in 50% N₂O und in der P/R-Gruppe mit 2 mg/kg/h Propofol und 0,5 μg/kg/min Remifentanil aufrechterhalten, wobei die Remifentanildosis nach 15 min halbiert wurde. Am Operationsende unmittelbar vor der Umlagerung in die horizontale Rückenlage wurde die Zufuhr der An?sthetika abrupt unterbrochen und folgende Aufwachzeiten erfa?t: Eintritt Spontanatmung (V_T>4 ml/kg), Extubation, Augen?ffnen, richtiges Benennen von Namen und Geburtsdatum und der Analgetikabedarf der ersten 2 postoperativen Stunden im Aufwachraum. Ergebnisse: Die Patienten der D/L-Gruppe reagierten auf den Intubationsreiz und die Hautinzision mit signifikanten Blutdruckanstiegen und zeigten signifikant h?here Herzfrequenzwerte, w?hrend ansonsten die h?modynamischen Parameter w?hrend des Narkoseverlaufs vergleichbar waren. Die Patienten der P/R-Gruppe erreichten signifikant früher eine stabile Spontanatmung (3,2 vs. 6,4 min), konnten früher extubiert werden (3,8 vs. 9,5 min), ?ffneten früher die Augen (3,0 vs. 11,5 min) und waren eher in der Lage, ihren Namen und Geburtsdatum zu benennen (4,8 vs. 14,3 min), wiesen aber auch signifikant h?ufiger Muskelzittern auf. Keine signifikanten Unterschiede fanden sich im Analgetikabedarf sowie in der Inzidenz von übelkeit und Erbrechen. Schlu?folgerung: Die Patienten erwachen aus der TIVA mit Propofol/Remifentanil schneller als aus der Desfluran/N₂O-Narkose und erreichen schneller ein h?heres Vigilanzniveau, wobei die geringe Intensit?t postoperativer Wundschmerzen nach Bandscheibenoperationen kein aufwendiges Konzept zur postoperativen Analgesie erfordert.      

Prostaglandin E1 attenuates the hypertensive response to tracheal extubation

Purpose

Tracheal extubation causes hypertension and tachycardia, which may cause imbalance between myocardial oxygen demand and supply in patients at risk of coronary artery disease. We conducted a randomized, controlled study to evaluate the effects of 0.05 or 0.1 μg · kg^?1 · min^?1 prostaglandin E₁, (PGE₁) iv on haemodynamic variables occurring during tracheal extubation and emergence from anaesthesia and compared them in patients receiving either lidocaine or saline.

Methods

Eighty ASA physical status I patients undergoing elective surgery were enrolled in the current study. Anaesthesia was maintained with sevoflurane 1.0%–2.5% (ET concentration) and nitrous oxide 60% in oxygen. Muscle relaxation was achieved with vecuronium. The patients were randomly assigned to receive one of four treatments (n = 20 each): saline (control), 0.05 μg · kg^?1 · min^?1 PGE₁, 0.1 μg · kg^?1 · min^?1 PGE₁, or 1 mg · kg^?1 lidocaine. PGE₁ was infused from completion of surgery until five minutes after tracheal extubation. Changes in heart rate (HR) and blood pressure (BP) were measured during and after tracheal extubation.

Results

In the control group, the HR, systolic BP, and diastolic BP increased during tracheal extubation. Administration of 0.1 μg · kg^?1 · min^?1 PGE₁ and 1 mg · kg^?1 lidocaine attenuated the increases in BP although 0.05μg · kg^?1 · min^?1 PGE₁ failed to do so. The inhibitory effect of the 0.1 μg · kg^?1 · min^?1 PGE₁ on BP was similar to that of lidocaine 1 mg · kg^?1 iv. The increase in HR was attenuated by lidocaine but not by PGE₁.

Conclusion

The intravenous infusion of 0.1 μg · kg^?1 · min^?1 PGE₁ given during emergence from anaesthesia and tracheal extubation is a useful method for attenuating the hypertension associated with noxious stimuli during this period.     

Improved postoperative analgesia with isoflurane than with propofol anaesthesia

Purpose

The impact of hypnotic drugs on postoperative analgesia has not been evaluated. We compared the influence of the maintenance of anaesthesia with either propofol or isoflurane on postoperative pain.

Methods

Forty ASA 1 -2 women, undergoing cosmetic abdominoplasty were randomized to receive either 6–12 mg·kg^?1·hr^?1 propofol iv (P, n = 20) or MAC 1 -1.5 isoflurane inhalation (Iso, n = 20). The lungs were ventilated with N₂O 60% and O₂ 40%, and I μg·kg^?1 fentanyliv provided intraoperative analgesia. Before surgical closure, 2 g propacetamoliv were administered. Postoperative analgesia was provided after hourly assessment of pain (VAS 0–100 mm), with 10 mg nalbuphineiv if VAS ≥ 50 mm, during the eight hours after surgery. Sedation score (awake 0 to unrousable 4) was also recorded. Analgesia satisfaction score (nil 0 to excellent 4) obtained from the patient on discharge.

Results

Sedation scores were similar in both groups except in the first postoperative hour, when it was higher in the Iso group. The VAS at rest (15.4 ± 18.6 vs 29.7 ± 19.8 mm,P = 0.0001) and nalbuphine requirements (0.13 ± 0.35vs 0.70 ± 0.80 doses,P = 0.004) were lower in the Iso group during the first six hours, although emesis was more frequent than in P (60vs 25%; P = 0.03). The incidence of analgesia satisfaction score (≥3) was similar between the two groups (P: 95; Iso: 75%).

Conclusion

These results suggested that isoflurane anaesthesia provides better analgesia than propofol anaesthesia in the first six hours after abdominoplasty.     

Neuromuscular effects of 600 μg·kg−1 of rocuronium in infants during nitrous oxide-halothane anaesthesia

Rocuronium bromide (Zemuron) is a new steroidal nondepolarizing neuromuscular blocking drug. We were interested in determining the effect of a bolus of rocuronium in infants during halothane anaesthesia as we did previously in older children. Eighteen infants (2-11 months) received a bolus of 600 μg·kg^?1, which is equal to twice the dose of rocuronium estimated to produce 95% depression of neuromuscular function (ED₉₅) in children (2-12 yr). Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Time (mean ± SEM, range) from administration of 600 μg·kg^?1 rocuronium to 90% (B₉₀) and 100% (B₁₀₀) neuromuscular block was 37 ± 2 (20-60) s and 64 ± 10 (20-180) s, respectively. The time to recovery of neuromuscular transmission to 10% (T₁₀) was 35.3 ± 3.0 (20.7-57.8) min and to 25% of baseline (T₂₅) was 41.9 ± 3.2 (24.3-67.7) min. The recovery index (T₂₅-T₇₅) was 26.6 ± 2.7 (11.7-44.5) min, and the time to recovery of the train-of-four ratio (T₄/T₁) ± 0.75 was 82.1 ± 6.9 (53.2-138.3) min. The plasma concentration of rocuronium when T₁ had recovered to about 30% was 654 ± 34 (417-852) ng·ml^?1 which is similar to that observed in children. Six-hundred μg·kg^?1 of rocuronium has a rapid onset of effect in infants and prolonged duration of action in infants compared to children.     

Low incidence of the oculocardiac reflex and postoperative nausea and vomiting in adults undergoing strabismus surgery

Purpose

To investigate the incidence of the oculocardiac reflex (OCR), and of postoperative nausea and vomiting (PONV) in adults undergoing strabismus surgery.

Methods

Adults (18 86 yr) undergoing inpatient strabismus surgery received 10 μg·kg atropine and 10 μg·kg alfentaniliv and were randomly allocated to: (A) 5 mg·kg^?1 thiopentoneiv, isoflurane/N₂O maintenance; (B) 3 mg·kg^?1 propofoliv. propofol/N₂O maintenance (10–14 mg·kg^?1hr·t-1); © 3 mg·kg^?1 propofoliv, propofol/air/O₂ maintenance (10–14 mg·kg^?1·hr^?1). Analyses were with the number-needed-to-treat/harm.

Results

In 97 adults the absolute nsk of OCR (13–20%) and PONV (21–31% after 24 hr) was low. with no differences between groups. Number-needed-to-treat to prevent PONV with propofol with or without N₂O compared with thiopentone-isoflurane was 7 to 11. Number-needed-to-harm for one OCR with propofol compared with thiopentone-isoflurane was 17.

Conclusion

Adults undergoing strabismus surgery with prophylactic atropine had a low risk of OCR and PONV independent of the anaesthetic technique used.     

Postoperative analgesia with “3-in-1” femoral nerve block after prosthetic hip surgery

Purpose

To evaluate the efficacy of a single shot “3-in-1” femoral nerve block for prosthetic hip surgery in association with general anaesthesia on post-operative analgesia.

Methods

Forty patients, ASA 1 to 3, received sham block or “3-in-1” femoral nerve block, following Winnie’s landmarks with a nerve stimulator, and 40 ml bupivacaine 0.5% with epinephrine were injected after induction of anaesthesia. Vecuronium, 0.1 mg· kg^?1, was added after performing the block and anaesthesia was maintained with isoflurane, oxygen 40% and nitrous oxide 60%. Fentanyl, 1.5 μg· kg^?1, was administered before incision to all patients. Heart rate, blood pressure, fentanyl requirements and F_ETiso were measured throughout surgery. During the post-operative period, 75 mg diclofenacim and/or 0.1 mg· kg^?1 morphine sc were administered when pain score was > 3/10 and repeated when necessary. Pain scores at first analgesic intervention, at 24 hr and 48 hr as well as diclofenac and morphine requirements after surgery were recorded.

Results

There was no difference in anaesthetic requirements during surgery. The time from performance of sham or “3-in-1” femoral nerve block to the first analgesic intervention (261 ± 49 min versus 492 ± 40 min,P < 0.05) and time from extubation to the first analgesic intervention (61 ± 44 minvs 298 ± 39 min,P < 0.05) were prolonged in the study group. However, pain scores and the analgesic requirements in the postoperative periods (24 and 48 hr) were similar.

Conclusion

There is a short-term benefit during the first few postoperative hours in using a single shot “3-in-1” femoral nerve block to complement general anaesthesia for elective hip surgery.     

Intubating conditions and neuromuscular block after divided dose mivacurium or single dose rocuronium

Purpose

To evaluate the tracheal intubating conditions and neuromuscular blocking charactenstics of divided dose mivacurium or single dose rocuronium.

Methods

Thirty-two patients undergoing elective surgery were studied. Anaesthesia was with propofol 2 mg · kg^?1, followed by an infusion of l50 μg · kg^?1 · min^?1. Patients were randomized to receive either mivacurium-0.15 mg · kg^?1 followed 30 sec later by 0.1 mg · kg^?1, or rocuronium-0.9 mg · kg^?1, followed 30 sec later by placebo. Tracheal intubating conditions were assessed 90 sec after the initial dose of relaxant by an anaesthetist who was unaware of patient group. The electromyographic (EMG) response of the first dorsal interosseus muscle to ulnar nerve train-of-four was measured.

Results

Successful tracheal intubation was performed in all patients after both mivacurium and rocuronium. Intubating conditions (jaw relaxation, open visible vocal cords) were judged to be good-excellent in all but one patient before insertion of the tracheal tube. However, patients receiving mivacunum were more likely to experience coughing and bucking after tracheal tube insertion (10/16 patients) than those receiving rocuronium (3/16 patients, P < 0.05). No patient in the rocuronium group experienced moderately vigorous coughing and bucking after insertion of the tracheal tube vs six patients in the mivacurium group (P < 0.05). Time to 10 and 25% recovery of neuromuscular function was faster (P < 0.05) after divided dose mivacunum (20 ± 1 and 23 ± 1 min, respectively) than after rocuronium (45 ± 5 and 57 ± 8 min, respectively).

Conclusion

The results suggest that, during conditions of the study, divided dose mivacurium is not recommended for a 90-sec tracheal intubation in patients where moderate coughing and bucking is deemed unacceptable.     

Pharmacodynamic behaviour of rocuronium in the elderly

This study compared the potency and time course of action of rocuronium (ORG 9426) in elderly and young patients during nitrous oxide-opioid anaesthesia. One hundred ASA physical status I– II patients (60, âgéd 65–80 yr, and 40, âgéd 20–45 yr) were studied by measuring the force of contraction of the adductor pollicis in response to train-of-four stimulation of the ulnar nerve. After induction of anaesthesia with thiopentone and maintenance with N₂O/O₂ and fentanyl, rocuronium 120,160, 200, or 240 μg · kg ^?1 was administered to determine dose-response curves. When maximum block had been obtained,further rocuronium to a total of 300 μg · kg ^?1 was given. Additional doses of 100 μg · kg^?1 were administered when the first twitch height (T₁) had recovered to 25% control. At the end of surgery neuromuscular blockade was allowed, whenever possible, to recover spontaneously until T₁ was 90% of control before administration of neostigmine. There was no difference in the potency of rocuronium in the elderly and the younger patients. The ED₅₀ was 196 ±8 (SEE for the mean) in elderly,vs 215 ±17 iμg · kg ^{? 1} in young patients (NS). When individual cumulative dose-response curves were constructed, the ED₅₀ was 203 ± 7(SEM) and 201 ± 10 μg · kg ^{? 1} in the elderly and the young respectively (NS). However, the onset of maximum neuromuscular block was slower in the elderly 3.7 ±1.1 (SD) vs 3.1 ± 0.9 min, P < 0.05). The time to 25% T ₁ recovery was longer in the elderly (11.8 ± 8.1 vs 8.0 ± 6.5 min,P <0.05) as was the recovery index, time from 25 to 75% T₁ recovery (15.5 ± 6.2 vs 11.2 ± 4.9 min, P< 0.05). The duration of neuromuscular block after each maintenance dose was longer in the elderly (P <0.01) and increased gradually with time. It is concluded that rocuronium is an intermediate-acting neuromuscular blocking drug with a similar potency in elderly and young patients, but the onset and recovery of neuromuscular blockade are slower in the elderly.     

Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED₅₀ doses (mean ± SD) being 149 ± 36 μg˙kg^?1 in infants, 205 ± 52 μg˙kg^?1 in children and 169 ± 47 μg˙kg^?1 in adults (P<0.05 between infants and children) and the ED₉₅ doses being 251 ± 73 μg˙kg^?1, 409 ± 71 μg˙kg^?1 and 350 ± 77 μg˙kg^?1, respectively (P<0.05 between all groups). The emg recovery following an average 94.5 ± 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED₉₅ dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.