Cuffed vs. uncuffed tracheal tubes in children: a randomised controlled trial comparing leak, tidal volume and complications.

Cuffed tracheal tubes are increasingly used in paediatric anaesthetic practice. This study compared tidal volume and leakage around cuffed and uncuffed tracheal tubes in children who required standardised mechanical ventilation of their lungs in the operating theatre. Children (0-16 years) undergoing elective surgery requiring tracheal intubation were randomly assigned to receive either a cuffed or an uncuffed tracheal tube. Assessments were made at five different time-points: during volume-controlled ventilation 6 ml.kg-1 , PEEP 5 cmH2 O and during pressure-controlled ventilation 10 cmH2 O / PEEP 5 cmH2 O. The pressure-controlled ventilation measurement time-points were: just before a standardised recruitment manoeuvre; just after recruitment manoeuvre; 10 min; and 30 min after the recruitment manoeuvre. Problems and complications were recorded. During volume-controlled ventilation, leakage was significantly less with cuffed tracheal tubes than with uncuffed tracheal tubes; in ml.kg-1 , median (IQR [range]) 0.20 (0.13-0.39 [0.04-0.60]) vs. 0.82 (0.58-1.38 [0.24-4.85]), respectively, p < 0.001. With pressure-controlled ventilation, leakage was less with cuffed tracheal tubes and stayed unchanged over a 30-min period, whereas with uncuffed tracheal tubes, leakage was higher and increased further over the 30-min period. Tidal volumes were higher in the cuffed group and increased over time, but in the uncuffed group were lower and decreased over time. Both groups showed an increase in tidal volumes following recruitment manoeuvres. There were more short-term complications with uncuffed tracheal tubes, but no major complications were recorded in either group at long-term follow-up. With standardised ventilator settings, cuffed tracheal tubes produced better ventilation characteristics compared with uncuffed tracheal tubes during general anaesthesia for routine elective surgery.

Monitoring temperature in children undergoing anaesthesia: a comparison of methods.

Children undergoing anaesthesia are prone to hypothermia. Perioperative monitoring of patient temperature is, therefore, standard practice. Postoperative temperature is regarded as a key anaesthetic performance indicator in Australian hospitals. Many different methods and sites of temperature measurement are used perioperatively. It is unclear to what degree these methods might be interchangeable. The aim of this study was to determine the relationships between temperatures measured at different sites in anaesthetised children. Two hundred children, 0 to 17 years, undergoing general anaesthesia for elective non-cardiac surgery, were prospectively recruited. Temperature measurements were taken in the operating theatre concurrently at the nasopharynx, tympanic membranes, temporal artery, axilla and skin (chest). Patient age and weight were documented. Temperatures varied according to site of measurement. The mean difference from nasopharyngeal temperature to temperatures at left and right tympanic, temporal, axillary and cutaneous sites were +0.24°C, +0.24°C, +0.35°C, -0.38°C and -1.70°C, respectively. Levels of agreement to nasopharyngeal temperature were similar at tympanic, temporal and axillary sites. Tympanic and temporal temperatures were superior to axillary temperatures for detection of mild hypothermia (<36°C). Skin temperature showed a large variation from nasopharyngeal measurements. Our findings indicate that measured temperatures vary between sites. Understanding these variations is important for interpreting temperature readings.

Paediatric cardiomyopathy and anaesthesia.

'Cardiomyopathy' (CM) is defined by the World Health Organization as 'a disease of the myocardium associated with cardiac dysfunction'. In a child, it is associated with a significant risk for anaesthesia. In addition, cardiac arrest under anaesthesia has been attributed to an undiagnosed CM. Care of these patients is complicated by the fact that there are several different forms of CM that have differing anaesthesia management goals, aimed at maintaining the patient's baseline haemodynamic variables of preload, heart rate, contractility, and afterload. With the emergence of new diagnostic tools, together with advances in cardiac imaging and improved treatment modalities (such as ventricular assist devices), the anaesthetic management of a child with a CM is evolving. This review describes the different forms of the disease in terms of pathology, aetiology, and clinical presentation. Dilated, hypertrophic, and restrictive CM are the most common forms. We examine recent advances in therapy, including the management of severe end-stage disease, while highlighting the specific anaesthetic considerations for children with each type of CM.

Fibreoptic assessment of paediatric sized laryngeal mask airways.

Laryngeal mask airways (LMA) are commonly used in paediatric anaesthesia. A well-placed LMA should provide a direct view of the vocal cords facilitating bronchoscopy or fibreoptic intubation. The aim of this audit was to assess the bronchoscopic view of the glottis obtained through an LMA with regard to its size. We prospectively assessed the position of LMAs in relation to the glottic aperture in 350 children (zero to seven years) undergoing elective fibreoptic examination of the upper and/or lower airways. Following induction of anaesthesia and positioning of the LMA, a fibreoptic evaluation of the view of the glottis was performed (complete, partial or no visualisation). Chest movement on manual ventilation was judged as good in the majority of patients and adequate for the remainder. No overt signs of airway obstruction were noted in any patient. However, a complete view of the glottic aperture was present in only 50% of size 1 LMAs, 57.5% of size 1.5, 72.7% of size 2 and 77.8% of size 2.5. The epiglottis impinged on the LMA opening, partially obstructing the view of the glottis in 36.3% of size 1 LMAs, 31.5% of size 1.5, 21% of size 2 and 17.8% of size 2.5. In 13.7% of size 1 LMAs, 11% of size 1.5, 6.3% of size 2 and 4.4% of size 2.5, the epiglottis was completely downfolded, obstructing the view of the glottic aperture. The findings indicate that even if ventilation is judged as adequate, smaller paediatric LMAs are more commonly associated with suboptimal anatomical positioning with partial obstruction of the glottic aperture than larger LMAs, and therefore may require repositioning more often.

rFV11a and paediatric open-heart surgery: thrombosis in the cardiopulmonary bypass circuit in spite of adequate markers of anticoagulation.

Recombinant activated factor V11 (rFV11a) is a relatively new procoagulant agent and its place in surgical practice continues to be investigated. We report the use of rFV11a to help manage bleeding in the operating theatre in a neonate, following weaning from cardiopulmonary bypass for arterial switch procedure, when bleeding continued in spite of maximal medical therapy and apparent exclusion of a surgical cause of bleeding. In this patient administration of rFV11a failed to facilitate haemostasis and cardiopulmonary bypass was re-instituted allowing location and repair of a small awkward surgical source. Separation from this additional 20 min of bypass was successful but a large thrombus was noted in the membrane oxygenator of the extracorporeal circuit in spite of the presence of adequate 'laboratory' markers of anticoagulation in the pump blood. No adverse sequelae to the patient occurred.

Pressure volume curves of paediatric laryngeal mask airways.

Hyperinflation of the laryngeal mask airway cuff may exert high pressure on pharyngeal and laryngeal structures. In vitro data show that high intra cuff pressures may occur when inflated to only 30% of the manufacturer's recommended maximum inflation volume. We prospectively assessed the pressure volume curves of paediatric sized laryngeal mask airways (size 1-3) in 240 consecutive children (0-15 years). Following laryngeal mask airway insertion the cuff was inflated with 1-ml increments of air up to the maximum recommended by the manufacturer. After each ml cuff pressure was measured. At the end all cuff pressures were adjusted to 55 cmH(2)O. The maximum recommended volume resulted in high intracuff pressures in all laryngeal mask airway brands and sizes studied. Approximately half the maximum volume produced a cuff pressure > or = 60 cmH(2)O. This occurred in all brands and all sizes studied. We recommend that cuff manometers should be used to guide inflation in paediatric laryngeal mask airways.

Laryngeal mask airway and tracheal tube cuff pressures in children: are clinical endpoints valuable for guiding inflation?

We prospectively assessed common clinical endpoints for their usefulness in avoiding hyperinflation of the cuffs of laryngeal mask airways (slight outward movement) and tracheal tubes (disappearance of an audible leak around the cuff during manual ventilation < 20 cm H(2)O) in 640 children. Cuff pressures were measured at induction and immediately before emergence from anaesthesia. With the laryngeal mask airway (sizes 1-4), the median cuff pressures ranged from 90 to > 120 cm H(2)O at induction and 105 to > 120 cm H(2)O before emergence. With tracheal tubes (sizes 3-7 mm), median cuff pressures were 40-60 cm H(2)O at induction and 45-70 cm H(2)O at emergence. With the use of nitrous oxide a consistent rise in cuff pressure was observed between the first and second readings whereas cuff pressures remained constant when nitrous oxide was not used. The use of clinical endpoints alone was associated with significant hyperinflation of cuffs with both devices in almost all patients, with an exacerbation when nitrous oxide was used. In order to avoid unnecessary cuff hyperinflation in laryngeal mask airways and tracheal tubes, the routine use of cuff manometers is mandatory in children.

Patterns of sevoflurane use in a children's hospital: the effects of a simple educational intervention.

We conducted a prospective observational study of sevoflurane use over a four-week period at our tertiary referral children's hospital. Sevoflurane vaporisers were weighed before and after all general anaesthesia sessions and anaesthesia time intervals recorded. Midway through the audit, the initial findings were presented to the department with a brief reminder of ways to reduce sevoflurane use. These included recommendations for fresh gas flows and use of alternative agents during maintenance. Sevoflurane use then continued to be audited over a further two-week period. Anaesthesia in induction rooms accounted for 60% of total sevoflurane use but involved only 15% of total general anaesthetic time. Thus sevoflurane was used eight times faster in the induction rooms when compared to operating theatres. There was a 53% reduction in the rate of use of sevoflurane after the educational intervention, with an 87% reduction in in-theatre use and a 31% reduction in induction room use. This represents a potential saving of $108,120 per annum in our institution. Workloads before and after the educational intervention were comparable. A more complete cost benefit analysis of this initiative would include the costs of alternative agents and any clinical disadvantages incurred and would be seen in the context of the overall health budget. This was beyond the scope of this project. Clinicians can be relatively complacent about financial accountability. In this study, a simple educational reminder halved sevoflurane use in the short term. This study suggests that specific reminders or recommendations about anaesthetic technique in the induction rooms may be indicated.

Caudal anaesthesia as a treatment for penile ischaemia following circumcision.

We report an ischaemic penile glans following circumcision and a dorsal penile nerve block in a 9-year-old boy. Ischaemia of the glans penis is a rare complication associated independently with both circumcision and dorsal penile nerve blocks. There are a number of pathophysiological mechanisms of this ischaemia and its management is varied and not well recorded. We report the successful management of this complication using a caudal epidural block and also discuss technical aspects of penile nerve blocks.