A comparison of the intubating and standard laryngeal mask airways for airway management by inexperienced personnel

Twenty-four inexperienced participants were timed inserting the intubating laryngeal mask airway and the laryngeal mask airway in 75 anaesthetised subjects. Adequacy of ventilation was assessed on a three-point scale. The pressure at which a leak first developed around the device's cuff was also measured. There was no significant difference in insertion time or the likelihood of achieving adequate ventilation between devices. However, the intubating laryngeal mask airway was better at providing adequate ventilation without audible leak (58/75 (77%) vs. 42/75 (56%); p = 0.009). The median (range [IQR]) pressure at which an audible leak developed was higher for the intubating laryngeal mask airway, 34.5 (14-40 [29-40]) cmH2O, than for the laryngeal mask airway, 27.5 (14-40 [22-33]) cmH2O (p < 0.001). The intubating laryngeal mask airway is worthy of further consideration as a tool for emergency airway management for inexperienced personnel.

Changes in brain natriuretic peptide concentrations following open cardiac surgery with cardioplegic cardiac arrest

Elevated brain natriuretic peptide (BNP) concentration in peripheral blood reflects impaired cardiac ventricular function. We investigated the release pattern of BNP following cardioplegic cardiac arrest during heart surgery. In particular, we sought to discover whether there is an increase in peripheral BNP concentrations following reperfusion of the ischaemic heart. A secondary aim of the study was to investigate whether allopurinol, an anti-oxidant, has any effect on BNP release. A total of 29 patients scheduled for elective coronary artery bypass grafting were recruited, of whom 12 were randomly allocated to receive allopurinol with their pre-medication. Blood specimens were taken at six time points from the indwelling arterial catheter, the first before surgery and the last 2 h following the termination of cardiopulmonary bypass (CPB). BNP was found to decrease markedly when the aortic cross clamp was applied and the heart was isolated from circulation (P=0.0001). There was a slight increase in BNP following cross clamp release and myocardial reperfusion (P=0.04). A more substantial increase occurred with weaning from CPB when ventricular filling occurred (P=0.0015). Only the final BNP value, 2 h after CPB, was elevated compared with baseline (P=0.0013). Allopurinol had no demonstrable effect on changes in BNP.

The implications of HIV for the anaesthetist and the intensivist

The acquired immune deficiency syndrome has reached pandemic proportions. Anaesthetists should be aware of the implications of dealing with increasing numbers of both diagnosed and undiagnosed, symptomatic and asymptomatic, human immunodeficiency virus-infected patients in the fields of intensive therapy, operating theatre anaesthesia, obstetrics and pain management. With recent advances, important insights have been gained into the pathogenesis of human immunodeficiency virus. Molecular techniques allow quantification of viral burden, and together with CD4 T-lymphocyte count, prognosis and response to therapy can be evaluated. New drugs and therapeutic regimens have improved prognosis for those who are infected with the virus and vertical transmission of infection from mother to infant can be minimised. Should accidental occupational exposure to the virus occur, a prophylactic regimen of antiretroviral drugs can be administered in an attempt to prevent subsequent human immunodeficiency virus infection.

Comparison of laryngeal mask and intubating laryngeal mask insertion by the naïve intubator

Seventy-five inexperienced participants were timed inserting the laryngeal mask airway (LMA) and the intubating laryngeal mask (ILM) in one of five cadavers. Adequacy of ventilation was assessed on a three-point scale depending on chest expansion and air leak. Participants were also asked to intubate the trachea via the ILM. The ILM was inserted faster than the LMA (P < 0.05) with a greater proportion achieving adequate ventilation after their first attempt (P < 0.05). Tracheal intubation via the ILM was completed successfully by 67% (52 of 75) of participants. In a questionnaire, participants stated that the ILM was easier to use and the preferred device in an emergency. The results suggest that inexperienced practitioners should use the ILM rather than the LMA for emergency ventilation.

The intubating laryngeal mask airway compared with direct laryngoscopy

We have compared the ability of naïve intubators to intubate the trachea using a laryngoscope and an intubating laryngeal mask airway (ILMA) after receiving basic training, in a randomized, prospective, crossover study in 60 patients. Ventilation of the lungs via the ILMA was also compared with ventilation with a face mask. There was no significant difference in successful intubation between the techniques (38 of 89 with the ILMA and 33 of 93 with direct laryngoscopy; ns). In patients in whom participants failed in their intubation attempts with the ILMA, investigators achieved success in 89% (16 of 18). Satisfactory ventilation was more common with the ILMA (50 of 51) than with the face mask (43 of 60) (P = 0.0001). A total of 98% (89 of 91) of ILMA were inserted successfully, with a mean insertion time of 19.6 s, and 78% (69/89) of these insertions were achieved in less than 26 s. The ILMA may be useful for emergency oxygenation and ventilation, but these results do not support its use for intubation by those not trained in advanced airway management and ILMA use.

Awake intubation of the difficult airway with the intubating laryngeal mask airway

The intubating laryngeal mask airway is a new device that facilitates intubation of the trachea. We assessed its use in 15 awake patients in whom we anticipated difficulty with tracheal intubation; we would otherwise have secured the patients' airways using a fibreoptic bronchoscope. All patients were sedated and had their airways anaesthetised with local anaesthetic. The tracheas of all 15 patients were successfully intubated. The mean time from start of sedation to successful intubation was 10.8 min. The mean time from completion of sedation and airway local anaesthesia to tracheal intubation was 2.8 min. Patients remained haemodynamically stable throughout, peripheral oxygen saturation was maintained and there were no obvious cases of pulmonary aspiration. Most patients complained of sore throat and hoarseness. We have demonstrated through this descriptive study that the intubating laryngel mask airway may, in certain circumstances, be used as an alternative to the fibreoptic bronchoscope.

Convection warmers--not just hot air

We sought to determine whether the forced air convection warmers (nine Bair Huggers, Augustine Medical, and one Warm Touch, Mallinkrodt Medical) used in our operating theatres could be a source of microbial pathogens. Agar plates were placed directly in the air stream of the warmers. Four of these grew potentially pathogenic organisms. When the warmers were set to blow through perforated blankets, no growth occurred. Three of the warmers were swabbed and sites of colonisation were found in their hoses. After fixing a microbial filter to the end of the hose, organisms were no longer detectable. We conclude that these warming devices are a potential source of nosocomial infection. They should only be used in conjunction with perforated blankets, should have their microbial filters changed regularly and their hoses sterilised. The inclusion of a microbial filter into the nozzle of the hose could be incorporated into the design of the warmer.