Propofol and alfentanil total intravenous anaesthesia: a comparison of techniques for major thoracic surgery.

BACKGROUND: Previous work has highlighted the disadvantages of propofol as a sole agent for total intravenous anaesthesia (TIVA). This randomised study investigated three combinations of propofol and alfentanil as TIVA for major thoracic surgery. METHODS: In 73 patients undergoing elective thoracic surgery, anaesthesia was conducted either with sodium thiopentone induction and inhalational maintenance (incorporating isoflurane) or with TIVA using propofol with alfentanil (by infusion at one of two rates or in incremental doses). Vital signs and recovery characteristics were recorded. RESULTS: There were no significant differences in heart rate or blood pressure between groups during either induction or maintenance. Depth of anaesthesia was controlled satisfactorily in all groups. Recovery characteristics were similar between treatment groups, although there was a trend towards earlier orientation in the group which received the highest infusion rate of alfentanil. CONCLUSION: Continuous infusions of propofol and alfentanil provide safe and reliable TIVA for major thoracic surgery. TIVA was found to be a satisfactory technique in more elderly patients than previously described. The higher of the two alfentanil infusion rates may result in a better combination of propofol and alfentanil with respect to recovery times than the lower.

Low gastric intramucosal pH: incidence and significance in intensive care patients.

Monitoring of gastric intramucosal pH (pHi) is advocated in critical illness to detect tissue acidosis due to regional hypoperfusion. However, the number of patients who may benefit from such monitoring remains unclear and the relationship between low pHi and outcome requires further definition. Sixty consecutive patients with Acute Physiology and Chronic Health Evaluation (APACHE II) scores < 30 were studied throughout ICU stay to investigate the incidence of low pHi (< 7.32 for > or = 1 hour), its relationship to outcome, and temporally associated clinical events. pHi was measured 2 to 6 hours post-ICU admission and 8-hourly thereafter. Forty-four patients (73%) exhibited low pHi. Fourteen patients died in ICU with 13 deaths occurring in the low pHi group (P = 0.05). Length of ICU stay was greater in the low pHi group (P = 0.02). The development of low pHi was temporally associated with maximal sepsis score, weaning from assisted ventilation and commencement of enteral feeding.

Investigation of a nosocomial outbreak of Pseudomonas aeruginosa pneumonia in an intensive care unit by random amplification of polymorphic DNA assay.

From July to September 1993 in the intensive care unit of the Royal Victoria Hospital there were 10 cases of pneumonia associated with sputum culture of Pseudomonas aeruginosa. The isolates had an identical biotype and pyocine typing profile. The same strain of P. aeruginosa was recovered from the sink plug-hole in two rooms, and the tap handles and ventilator tubing in a third room. All strains were retrospectively typed by the random amplification of polymorphic DNA (RAPD) method using a 26-mer oligonucleotide primer, and were identical in profile. Recommendations to medical and nursing staff included secretion isolation precautions, terminal disinfection after patient discharge, use of disposable vinyl gloves by hospital staff for all body substance contacts, thorough handwashing with 4% chlorhexidine gluconate before and after dealing with all patient contacts, and prompt, appropriate antibiotic treatment for P. aeruginosa pneumonia. RAPD is a simple and effective method to determine the relatedness of P. aeruginosa isolates, and typing results are available within a single working day; thus dramatically increasing its clinical relevance over existing molecular methods.

Correction of splanchnic oxygen deficit in the intensive care unit: dopexamine and colloid versus placebo.

Correction of the splanchnic oxygen deficit indicated by low gastric intramucosal pH (pHi < 7.35) appears to reduce ICU mortality. Dopexamine hydrochloride is in clinical use for this purpose but its efficacy has not been fully investigated. We report the results of a prospective, randomized, placebo-controlled study with a crossover design to assess the efficacy of dopexamine in correcting low pHi. Twelve patients in whom pHi < 7.32 was detected during eight-hourly monitoring were randomized to receive either incremental dopexamine (4-6 micrograms/kg/min) with colloid or 5% dextrose for three hours prior to crossover. There was no difference in pHi between treatments despite cardiovascular effects during dopexamine infusion. There was, however, a time-related increase in pHi suggesting a beneficial effect of conventional therapy. Dopexamine hydrochloride at 4-6 micrograms/kg/min in conjunction with colloid is not a clinically useful therapy to correct the splanchnic oxygen deficit indicated by low pHi.

Does the choice of the neuromuscular blocking agent affect the cardiovascular response to intubation?

Heart rate and arterial pressure changes induced by tracheal intubation, 3 min after administration of atracurium, vecuronium, tubocurarine, pancuronium or alcuronium, have been studied under thiopentonenitrous oxide-oxygen anaesthesia supplemented by either 0.5% halothane or fentanyl 2 micrograms kg-1. Pancuronium and alcuronium were associated with the greatest increase in heart rate and tubocurarine with the greatest decrease in arterial pressure prior to intubation. Following intubation, all groups, with the exception of tubocurarine showed a similar and significant rise in heart and arterial pressure when compared with control values. The cardiovascular response to intubation, particularly the effect on heart rate, was less marked when fentanyl was given at induction and was short lived with atracurium and vecuronium. Although those patients who received tubocurarine showed no significant rise in arterial pressure following tracheal intubation, this was due to significant hypotension occurring in this group prior to intubation.

Age and nature of operation influence the pharmacokinetics of midazolam.

The pharmacokinetics of midazolam were studied in surgical patients given 0.3 mg kg-1 i.v. for either the induction of anaesthesia, or postoperative sedation following cardiopulmonary bypass. The short elimination half-life of midazolam (2.4 h in patients less than 50 yr undergoing minor surgery) was significantly, although not markedly, prolonged with age (4.1 h in patients greater than 50 yr undergoing minor procedures) and by the nature of the operation (3.8 h after major operative procedures). These changes were the result of alterations in clearance and volume of distribution with age, and in volume of distribution with nature of operation.

Pharmacokinetics of diazepam and midazolam when used for sedation following cardiopulmonary bypass.

The water-soluble benzodiazepine, midazolam, was compared with diazepam for postoperative sedation in patients following cardiopulmonary bypass. Midazolam in repeated doses produced a stable plasma concentration within 4 h, showed no tendency to cumulation and was cleared rapidly following discontinuation. Similar doses of diazepam given with the same frequency produced plasma concentrations which were still increasing at the time of discontinuation and which were still greater than their baseline values 24 h later.

Vecuronium and atracurium in the elderly: a clinical comparison with pancuronium.

The intubating conditions, time to complete block and duration of clinical relaxation were observed in a group of 101 elderly patients (aged over 65 years) following pancuronium 0.1 mg kg-1, vecuronium 0.1 mg kg-1 or atracurium 0.5 mg kg-1. The intubating conditions in the three groups were similar when assessed at 2 min following relaxant administration. The time to complete block was shortest with vecuronium (4.3 min) in comparison to atracurium (5.0 min) and pancuronium (6.0 min), but the differences were not statistically significant. The duration of clinical relaxation, however, was significantly shorter with vecuronium (37 min) and atracurium (35 min) in comparison to pancuronium (99 min).

Failure of two benzodiazepines to prevent suxamethonium-induced muscle pain.

In a randomised double-blind trial carried out on fit, unpremedicated patients undergoing standard minor operations with early postoperative mobility, using a standard form of anaesthesia, pretreatment with diazepam 0.15 mg/kg or midazolam 0.1 mg/kg failed to reduce significantly the incidence of postoperative muscle pains following suxamethonium 1 mg/kg. By contrast, tubocurarine 0.05 mg/kg proved to be effective as a pretreatment. Neither benzodiazepine influenced the incidence or severity of fasciculations seen with suxamethonium or the duration of neuromuscular block. Tubocurarine virtually abolished visible fasciculation and, in the dose used, reduced the intensity and duration of the neuromuscular block. There were no clinically significant changes in serum potassium, creatinine phosphokinase or aldolase after suxamethonium, although 5 out of 47 showed an atypical rise in creatinine phosphokinase.