Mortality associated with anaesthesia: a qualitative analysis to identify risk factors.

From a prospectively defined cohort of patients who underwent either general, regional or combined anaesthesia from 1 January 1995 to 1 January 1997 (n = 869 483), all consecutive patients (n = 811) who died within 24 h or remained unintentionally comatose 24 h after anaesthesia were classified to determine a relationship with anaesthesia. These deaths (n = 119; 15%) were further analysed to identify contributing aspects of the anaesthetic management, other factors and the appropriateness of care. The incidence of 24-h peri-operative death per 10 000 anaesthetics was 8.8 (95% CI 8.2-9.5), of peri-operative coma was 0.5 (0.3-0.6) and of anaesthesia-related death 1.4 (1.1-1.6). Of the 119 anaesthesia-related deaths, 62 (52%) were associated with cardiovascular management, 57 (48%) with other anaesthetic management, 12 (10%) with ventilatory management and 12 (10%) with patient monitoring. Inadequate preparation of the patient contributed to 30 (25%) of the anaesthesia-related deaths. During induction of anaesthesia, choice of anaesthetic technique (n = 18 (15%)) and performance of the anaesthesiologist (n = 8 (7%)) were most commonly associated with death. During maintenance, the most common factors were cardiovascular management (n = 43 (36%)), ventilatory management (n = 12 (10%)) and patient monitoring (n = 12 (10%)). In both the recovery and the postoperative phases, patient monitoring was the most common factor (n = 12 (10%) for both). For cardiovascular, ventilatory and other anaesthetic management, human failure contributed to 89 (75%) deaths and organisational factors to 12 (10%). For inadequate patient monitoring, human factors contributed to 71 (60%) deaths and organisational factors to 48 (40%). Other contributing factors were inadequate communication (30 deaths (25%) for all four aspects of the anaesthetic management) and lack of supervision (particularly for ventilatory management). Inadequate care was delivered in 19 (16%) of the anaesthesia-related deaths with respect to cardiovascular management, in 20 (17%) with respect to ventilatory management, in 18 (15%) with respect to patient monitoring and in 23 (19%) with respect to other anaesthetic management.

Anaesthesia for day care surgery, patient selection, evaluation, preoperative preparation and selection of drugs.

Paediatric patients are a challenge to the anaesthetist because of their specific differences in behaviour, physiology, pharmacology, congenital anomalies and pathology. The number of day care paediatric patients show a steady increase. It is important that anticipated anaesthetic problems are solved or prevented by a good preoperative evaluation and preparation. Adequate psychological preparation and parental presence on induction and recovery have been shown to be a very good, if not the best premedication especially for toddlers. Relaxation of fluid restriction has led to more cooperation of the paediatric patient. Provided physicians, anaesthetists, surgeons and nurses share the same positive view on day care surgery, the facility will be greatly appreciated by both children and their parents.

Patient controlled analgesia in children and adolescents: a randomized controlled trial.

In children, patient controlled analgesia (PCA) and continuous infusion (CI) of morphine are well established methods of relieving postoperative pain. This study was designed to assess the efficacy of PCA plus background infusion (BI) (15 microg x kg(-1) x h(-1) and bolus doses of 15 microg x kg(-1) with a lock-out interval of 10 min) with CI (20 to 40 microg x kg(-1) x h(-1)) in terms of analgesia, morphine needs and side-effects. A stratified randomized controlled trial was carried out. 47 children aged 5-18 years undergoing major elective lower/upper abdominal or spinal surgery were allocated. The magnitude of surgery was assessed by the Severity of Surgical Stress scoring (SSS) system. Pain was assessed by self-report every three h. Side-effects compatible with morphine as well as morphine consumption were recorded. Morphine consumption was significantly increased in the PCA group compared with the CI group. Moreover, morphine consumption was associated with SSS, independent of the technique of administration. There were no significant differences between groups in pain scores or in the incidence of side-effects.

Safety and efficacy of semi-closed circle ventilation in small infants.

The purpose of this clinical trial was to investigate the safety and efficacy of semi-closed circle ventilation of the Dräger anaesthesia ventilators (Cicero, Cato), using a fresh gas flow (FGF) of 600 ml.min-1. Twenty infants, weighing less than 6000 g, without cardiorespiratory abnormalities who required general anaesthesia of at least 30 min were included. The FGF was reduced to 600 ml.min-1 after 10 min of denitrogenation with a FGF of 4 to 61.min-1. The composition of the FGF (600 ml.min-1) was calculated as follows: oxygen necessary for consumption (60 ml.min-1) plus the remaining FGF in a 1:2 relationship for oxygen. The inspiratory nitrogen fraction was calculated to exclude accumulation. Inspiratory fractions of O2 and N2O plus inspiratory and endtidal CO2 partial pressures and noninvasive oxygen saturation were the control parameters. The gas concentrations (O2 and N2O) remained within safe limits. Hypoxic gas concentrations were not observed. Neither nitrogen nor CO2 accumulated in the circle system. In conclusion, low flow anaesthesia can be performed safely in infants under 6000 grams with the Dräger Cicero and Cato anaesthesia ventilators.

Dutch case-control study of anaesthesia-related morbidity and mortality. Rationale and methods.

To date, anaesthesia-related mortality, morbidity and risk factors have almost exclusively been studied qualitatively rather than quantitatively. Therefore, knowledge of the relative risk associated with many anaesthesia-related factors is still lacking. Recently, a quantitative study of the determinants and prevention of morbidity and mortality in anaesthesia was started in the Netherlands. Its objective is to study severe peri-operative morbidity and mortality as a function of anaesthesia-related risk factors. The study is designed as a case-control study within a prospectively defined cohort. The cohort comprises all patients undergoing an anaesthetic procedure, either general, regional or a combination, in one of 61 hospitals between 1 January 1995 and 1 January 1997. A 'case' is a patient who dies within 24 h of undergoing an anaesthetic procedure or who remains comatose 24 h after an anaesthetic procedure. A 'control' patient is a randomly chosen patient who has undergone anaesthesia and is matched for gender and age. The present report discusses the study protocol.

Forces applied during laryngoscopy in children. Are volatile anaesthetics essential for suxamethonium induced muscle rigidity?

Increased masticatory muscle tone after administration of suxamethonium has been demonstrated in children when combined with volatile anaesthetics. Whether volatiles are a prerequisite for this phenomenon is not known. In this study upper airway muscle tone, including the tone of the masticatory muscles, was determined in 54 children (age range 2-15 years), anaesthetized with propofol, fentanyl and nitrous oxide and avoiding any use of volatiles. The children were either relaxed with suxamethonium (n = 26) or vecuronium (n = 28). The forces applied during laryngoscopy were used to quantify upper airway muscle tone and were significantly greater in the suxamethonium group than in the vecuronium group: maximally applied force was 25 N versus 21 N (P = 0.008), and mean applied force was 16 N versus 13 N (P = 0.006), respectively. The results of this study indicate that upper airway muscle tone increases after administration of suxamethonium in children independent of the presence of volatile anaesthetics. Moreover, increased muscle tone had no effect on the difficulty of laryngoscopy or the intubation conditions. Increased masseter muscle rigidity after suxamethonium could be due to the very unique characteristics of this muscle.

Complications of rigid laryngo-bronchoscopy in children.

Twenty-five complications (of which 2 were lethal) occurred in 1332 rigid laryngo-bronchoscopies performed under general anesthesia in the Sophia Children's Hospital during an 8 year period (1982-1990). The nature and circumstances of these complications were studied retrospectively. Important intraoperative complications were hemorrhage and cardiac arrhythmia; postoperative complications were intoxication and respiratory complications. Three risk factors: tetralogy of Fallot, biopsy/drainage, and extraction of an aspirated foreign body appeared to be significantly associated with complications. The results of this study were compared with those reported in studies of rigid and flexible laryngo-bronchoscopies in children.

Propofol requirements for induction of anesthesia in children of different age groups.

To demonstrate any age-related differences in propofol requirements for induction of anesthesia, 150 healthy children aged 3-5 yr (n = 50), 6-9 yr (n = 50), and 10-15 yr (n = 50) scheduled for outpatient surgery were randomly assigned to receive an induction dose of propofol of 1.5, 2.0, 2.5, 3.0, or 3.5 mg/kg. To limit pain during injection, alfentanil (5 micrograms/kg) was administered before the propofol. Patients were classified as asleep or not asleep 30 s after the propofol. Incidence of excitation, injection pain, and apnea during induction of anesthesia were noted; arterial blood pressure and heart rate were recorded for 5 min after induction. More than 95% of the children were asleep in the dose groups receiving > or = 2.5 mg/kg. The number of patients falling asleep after receiving 1.5 mg/kg of propofol increased significantly with increasing age (P < 0.05); the difference between the oldest and the youngest age groups was the most significant (P < 0.05). Significant decreases in mean arterial blood pressure and heart rate occurred after induction in all dose and age groups without any systematic intergroup differences. Apnea occurred more frequently in older children (P < 0.01) and with larger doses (P < 0.01). The most frequent side effect was erythema near the site of injection, and its occurrence was dose dependent. The authors conclude that 2.5 mg/kg of propofol, if preceded by 5 micrograms/kg of alfentanil, is an appropriate induction dose for children aged 3-15 yr and that the sleep response to 1.5 mg/kg is more in older children.

[Pediatric anesthesiology]. / Kinderanesthesiologie.

Paediatric anaesthesia varies from anaesthesia administered to the adult. No one would now doubt the value of paediatrics as a separate specialty- but what of its various branches? In the instance of anaesthesia it is believed that a very good case indeed can be made for a distinct specialty, because in paediatric anaesthesia the infant's needs are fundamentally different from those of the adult. It is not simply a question of adjusting doses or the parameters of ventilation to a scale related to weight or surface area. The anatomy, physiology, biochemistry, pharmacology and pathology of the infant generally and of the neonate in particular differ greatly from those of the adult. Each type of surgery has its special problems, and again these are different when applied to the infant. In this paper a few of the differences with their implications on anaesthetic practice are emphasized. Last but not least the psychological responses of infants and children of various ages to anaesthesia are explained.