Background and objective: To evaluate the ease with which successful insertion of a laryngeal mask airway can be performed in comparison with endotracheal intubation by medical personnel wearing chemical protective equipment.

Methods: Anaesthetists and non-anaesthetists (each n = 20) participated in the prospective comparative trial in an animal laboratory. The time and success rates of laryngeal mask airway vs. endotracheal tube insertions were measured as performed on anaesthetized monkeys.

Results: The results showed that the laryngeal mask airway was inserted more rapidly than the endotracheal tube by both groups (3.6 s and 28.6 s, P < 0.0001). Failed intubation occurred in 35% (anaesthetists) vs. 55% (non-anaesthetists) (P = 0.17).

Conclusions: In view of the 100% success rate of insertion even in unfavourable conditions, the possible role of the laryngeal mask airway in the scenario of a toxic mass casualty event should be considered.

Background and objective: Pain following the injection of propofol is a common problem. It is often treated by the coadministration of intravenous lidocaine. Iontophoresis, which facilitates the delivery of charged molecules such as lidocaine to body tissues, may be a practical alternative to lessen the pain.

Methods: The iontophoretic application of lidocaine was compared with intravenous lidocaine to assess the relative efficacy of reducing pain during propofol administration.

Results: The incidence rate of moderate or severe pain was significantly greater in the iontophoresis group (26.7 compared with 6.9% in the intravenous lidocaine group) (P < 0.05).

Conclusions: The iontophoretic administration of lidocaine 60 mg does not compare favourably with lidocaine 40 mg mixed with propofol for the reduction of pain on administration of propofol.

Background and objective: It was previously reported that topical ketamine inhibits albumin extravasation in a rat chemical peritonitis model. Using the same model, the present study investigated whether intravenous ketamine inhibited this extravasation.

Methods: Twenty-four rats anaesthetized with pentobarbital (75 mg kg−1) were randomly assigned to two groups: ketamine and a 0.9% NaCl (saline) group (n = 12 each). Ketamine 1% or saline 0.1 mL kg−1 min−1 was given intravenously for 60 min to the respective group. After the abdomen had been opened, peritonitis was elicited by topically applying a filter paper containing 0.02 M HCl 0.07 mL onto the surface of the appendix or caecum for 5 min. Fifteen minutes after removal of the filter paper, Evans' blue dye (50 mg kg−1) was injected intravenously. The extravasated dye was colorimetrically quantified by a spectrophotometer at 620 nm.

Results: The infusion of ketamine significantly reduced Evans' blue extravasation: 5.26 (range 4.18–6.34) μg per 100 mg tissue compared with the saline group control: 6.81 (5.93−7.69) μg per 100 mg tissue (P < 0.05).

Conclusions: It is suggested that ketamine anaesthesia may reduce albumin extravasation in inflammatory tissues.

Background and objective: Pharmacokinetics of propofol in rats have usually been described using linear models. Furthermore, there are only a few investigations for a pharmacodynamic model of the electroencephalographic effects of propofol in rats. We investigated pharmacokinetics and pharmacodynamics of propofol in rats with special regard to linearity in pharmacokinetics and development of tolerance.

Methods: Twelve adult male Sprague-Dawley rats received propofol in three successive infusion periods of 30 min each with infusion rates of 0.5, 1 and 0.5 mg kg−1 min−1. Propofol plasma concentrations were determined from arterial blood samples. Pharmacokinetics were tested for linearity using the ratio of the concentrations at the end of the first and second infusion interval as a model independent criterion. Several linear and nonlinear models were investigated with population pharmacokinetic analysis. Pharmacodynamics were analysed using the median frequency of the electroencephalographic power spectrum as a quantitative measure of the hypnotic effect.

Results: Pharmacokinetics were found to be nonlinear and were best described by a two-compartment model with Michaelis-Menten elimination (Vm = 2.17 μg mL−1 min−1, Km = 2.65 μg mL−1, k12 = 0.30 min−1, k21 = 0.063 min−1, Vc = 0.13 L). Acute tolerance to the electroencephalographic effect of propofol was observed. The hypnotic effect was best described by a sigmoid Emax model (E0 = 17.8 Hz, Emax = 17.7 Hz, EC50 = 4.1 μg mL−1, γ = 2.3, ke0 = 0.36 min−1) with competitive antagonism of propofol and a hypothetical drug in an additional tolerance compartment.

Conclusions: For the applied infusion scheme, propofol pharmacokinetics in rats were nonlinear and a development of tolerance to the electroencephalographic effect of propofol was observed during an infusion time of 90 min.

Background and objective: Children are vulnerable to regurgitation with a relatively high incidence of aspiration during general anaesthesia which is attributed to the high intragastric pressure, a short oesophagus, an immature laryngeal reflex and incomplete lower oesophageal sphincter muscle function. Subcutaneous administration of epinephrine is generally used in surgery to decrease bleeding due to local vasoconstriction. The effect of epinephrine on the sphincter muscle tone was investigated during general anaesthesia in children.

Methods: Ten children scheduled for skin graft or plastic surgery of the ear were studied. A gastrointestinal pressure sensor was inserted nasally, and the intraluminal pressures of the lower oesophagus, lower oesophageal sphincter and stomach were monitored under sevoflurane, nitrous oxide anaesthesia. The effect of epinephrine on the lower oesophageal sphincter muscle tone was measured.

Results: The resting pressure of the lower oesophageal sphincter muscle tone significantly decreased from 4.56 ± 1.85 to 3.79 ± 1.11 kPa after 3 μg kg−1 epinephrine for 4 min. The barrier pressure is the difference between the lower oesophageal sphincter and intragastric pressure, and that decreased to 1.23 ± 1.17 kPa from the 2.07 ± 1.77 kPa resting level. The observations implied that epinephrine had a long-lasting relaxing effect on lower oesophageal sphincter muscle in children.

Conclusions: The observations may give some explanation about the mechanism of gastro-oesophageal reflux during general anaesthesia, especially in the participation of the adrenergic receptors.

Background and objective: Excessive alcohol consumption is a major cause for premature death and preventable ill health in the whole population. We set out to audit admissions to the intensive care unit (ICU) of our large teaching hospital with respect to alcohol-related admissions.

Methods: A prospective audit was conducted into alcohol-associated admissions to our university hospital adult ICU over 12 months. The following data were collected for each patient admitted: age, gender, diagnosis and amount of alcohol consumption, APACHE II score, and the probability of death.

Results:Patients with definite alcohol consumption constituted 39.1% (124 patients) of all admissions (317 patients) to the ICU. In Group 1 (89 patients), the admission was directly associated with alcohol consumption, which included heavy alcohol consumption. Group 2 (35 patients) consisted of ‘social drinkers’ and Group 3 was composed of patients who denied any alcohol intake. Group 1 had a high median APACHE II score of 19 (range 4–35) and a significantly higher mortality rate (41.6%) than Group 3 (18.4%, P < 0.001) or the entire sample studied (23.7%,P < 0.001). The results also demonstrated an incidence of pneumonia of 29.2% (26 patients) in alcohol-associated admissions compared with 22.8% (eight patients) in Group 2 and 21.8% (19 patients) in Group 3. Trauma admissions amounted to 11.4% of the patients studied (24/211 patients), 17 (70.8%) of whom were directly associated with alcohol and it included 11 pedestrians.

Conclusions: Alcohol may play a major role in the admission and mortality of ICU patients. Further investigations are warranted because our sample size is so small.

Background and objective: Unilateral paravertebral nerve blockade has been reported to produce excellent afferent nerve block, reduce the incidence of postoperative nausea and vomiting, and reduce hospital stay following inguinal hernia repair. The aim was to compare the use of bilateral paravertebral blocks to regular general anaesthesia for ventral hernia repair.

Methods: Sixty patients were prospectively allocated to receive either bilateral paravertebral nerve blockade (midazolam for block; supplemented with light intraoperative sedation if needed) or general anaesthesia for ventral hernia repair. The end-points of the study were length of hospital stay, postoperative analgesia (visual analogue scale, supplemental opioid requirement) and incidence of postoperative nausea and vomiting.

Results: The duration of hospital stay was observed to be shorter in patients handled with bilateral paravertebral nerve blockade (2.3 [SD 1.3] days) compared with patients receiving general anaesthesia (4.1 (3.0) days). Paravertebral analgesia resulted in both lower visual analogue scores and a significantly reduced need for supplemental opioid administration during the first 48 h postoperatively compared with general anaesthesia (P < 0.001). The rate of postoperative nausea and vomiting in the paravertebral nerve blockade group was only 3.3%, while 26.7% of patients in the general anaesthesia group suffered from postoperative nausea and vomiting (P < 0.05). Paravertebral nerve blockade was associated with good patient acceptance in 90% of patients.

Conclusions: Bilateral paravertebral blockade combined with light intravenous sedation was superior to general anaesthesia for ventral hernia repair. Paravertebral blockade was associated with shorter hospital stay, improved analgesia and less postoperative nausea and vomiting. It is suggested that this technique deserves more widespread use in patients undergoing ventral hernia repair.

Background and objective: To compare the application of the cuffed oropharyngeal airway and the laryngeal mask airway on anaesthetized adult patients undergoing minor outpatient surgery.

Methods: One hundred patients received intravenous fentanyl, propofol and N2O for the induction and maintenance of anaesthesia. The patients were randomly divided into two groups: a cuffed oropharyngeal airway group (n = 50) and a laryngeal mask airway group (n = 50). After insertion of the device, fibreoptic laryngoscopy was attempted and the degree of success scored. We then compared the first application success rate of both procedures while judging airway intervention requirement, fibreoptic scores, adverse airway events and haemodynamic tolerance.

Results: Both devices had an almost similar first-time placement rate (cuffed oropharyngeal airway 84% versus laryngeal mask airway 96%). The cuffed oropharyngeal airway required a higher number of airway interventions (P < 0.001). The laryngeal mask airway had a significantly better fibreoptic view compared with the cuffed oropharyngeal airway (P < 0.001). However, the number of adverse airway events was lower in the cuffed oropharyngeal airway group; there were no significant differences in adverse events and haemodynamic variables between the said two groups.

Conclusions: The results suggest that the cuffed oropharyngeal airway was an effective alternative airway in spontaneously breathing patients during short procedures.