Neil A. Chambers

Risk assessment for respiratory complications in paediatric anaesthesia: A prospective cohort study

BACKGROUND Perioperative respiratory adverse events in children are one of the major causes of morbidity and mortality during paediatric anaesthesia. We aimed to identify associations between family history, anaesthesia management, and occurrence of perioperative respiratory adverse events. METHODS We prospectively included all children who had general anaesthesia for surgical or medical interventions, elective or urgent procedures at Princess Margaret Hospital for Children, Perth, Australia, from Feb 1, 2007, to Jan 31, 2008. On the day of surgery, anaesthetists in charge of paediatric patients completed an adapted version of the International Study Group for Asthma and Allergies in Childhood questionnaire. We collected data on family medical history of asthma, atopy, allergy, upper respiratory tract infection, and passive smoking. Anaesthesia management and all perioperative respiratory adverse events were recorded. FINDINGS 9297 questionnaires were available for analysis. A positive respiratory history (nocturnal dry cough, wheezing during exercise, wheezing more than three times in the past 12 months, or a history of present or past eczema) was associated with an increased risk for bronchospasm (relative risk [RR] 8.46, 95% CI 6.18-11.59; p<0.0001), laryngospasm (4.13, 3.37-5.08; p<0.0001), and perioperative cough, desaturation, or airway obstruction (3.05, 2.76-3.37; p<0.0001). Upper respiratory tract infection was associated with an increased risk for perioperative respiratory adverse events only when symptoms were present (RR 2.05, 95% CI 1.82-2.31; p<0.0001) or less than 2 weeks before the procedure (2.34, 2.07-2.66; p<0.0001), whereas symptoms of upper respiratory tract infection 2-4 weeks before the procedure significantly lowered the incidence of perioperative respiratory adverse events (0.66, 0.53-0.81; p<0.0001). A history of at least two family members having asthma, atopy, or smoking increased the risk for perioperative respiratory adverse events (all p<0.0001). Risk was lower with intravenous induction compared with inhalational induction (all p<0.0001), inhalational compared with intravenous maintenance of anaesthesia (all p<0.0001), airway management by a specialist paediatric anaesthetist compared with a registrar (all p<0.0001), and use of face mask compared with tracheal intubation (all p<0.0001). INTERPRETATION Children at high risk for perioperative respiratory adverse events could be systematically identified at the preanaesthetic assessment and thus can benefit from a specifically targeted anaesthesia management. FUNDING Department of Anaesthesia, Princess Margaret Hospital for Children, Swiss Foundation for Grants in Biology and Medicine, and the Voluntary Academic Society Basel.

Impact of laryngeal mask airway cuff pressures on the incidence of sore throat in children

Background:  Hyperinflation of laryngeal mask airway cuffs can cause harm to the upper airway mainly by exerting high pressures on pharyngeal and laryngeal structures thus impairing mucosal perfusion. Although cuff manometers can be used to guide the monitoring of cuff pressures, their use is not routine in many institutions. In a prospective audit, we assessed the incidence of sore throat following day‐case‐surgery in relation to the intracuff pressure within the laryngeal mask airway.

Monitoring electrical skin conductance: a tool for the assessment of postoperative pain in children?

Background:Monitoring changes in electrical skin conductance has been described as a potentially useful tool for the detection of acute pain in adults. The aim of this study was to test the method in pediatric patients. Methods:A total of 180 postoperative pediatric patients aged 1–16 yr were included in this prospective, blinded observational study. After arrival in the recovery unit, pain was assessed by standard clinical pain assessment tools (1–3 yr: Face Legs Activity Cry Consolability Scale, 4–7 yr: Revised Faces Scale, 8–16 yr: Visual Analogue Scale) at various time points during their stay in the recovery room. The number of fluctuations in skin conductance per second (NFSC) was recorded simultaneously. Results:Data from 165 children were used for statistical analysis, and 15 patients were excluded. The area under the Receiver Operating Characteristic curve for predicting moderate to severe pain from NFSC was 0.82 (95% confidence interval 0.79–0.85). Over all age groups, an NFSC cutoff value of 0.13 was found to distinguish between no or mild versus moderate or severe pain with a sensitivity of 90% and a specificity of 64% (positive predictive value 35%, negative predictive value 97%). Conclusions:NFSC accurately predicted the absence of moderate to severe pain in postoperative pediatric patients. The measurement of NFSC may therefore provide an additional tool for pain assessment in this group of patients. However, more research is needed to prospectively investigate the observations made in this study and to determine the clinical applicability of the method.

Tramadol vs morphine during adenotonsillectomy for obstructive sleep apnea in children.

Background:  Optimal analgesia for children undergoing adenotonsillectomy for obstructive sleep apnea (OSA) is controversial. Tramadol may represent a superior choice over morphine in this group, with a potential to cause less postoperative sedation and respiratory depression. Optimal perioperative analgesia may allow expensive and time‐consuming preoperative work‐up and postoperative monitoring to be rationalized.

Reduced air leakage by adjusting the cuff pressure in pediatric laryngeal mask airways during spontaneous ventilation

Background:  Optimal inflation of the laryngeal mask airway (LMA) cuff should allow ventilation with low leakage volumes and minimal airway morbidity. Manufacturer’s recommendations vary, and clinical end‐points have been shown to be associated with cuff hyperinflation and increased leak around the LMA. However, measurement of the intra‐cuff pressure of the LMA is not routine in most pediatric institutions, and the optimal intra‐cuff pressure in the LMA has not been determined in clinical studies.

Induction of anesthesia in a combative child; management and issues

A developmentally delayed, 13‐year old autistic boy required management of multifocal cerebral and pulmonary tumors, involving several anesthetics over a 4‐month period. At each anesthetic he refused premedication, displayed increasing anxiety and became more combative. With parental guidance and involvement, a variety of anesthetists tried a range of techniques to achieve induction, each ultimately resorting to the use of physical restraint. Principles essential to the care of such a child include early recognition, parental support, multi‐disciplinary planning of procedures requiring general anesthesia, continuity of anesthesia care, and clear guidelines about the perioperative management of uncooperative children, including the ethical use of restraint.

Airway management of three cases of congenital cervical teratoma

Cervical teratomas are rare congenital tumors derived from all three germ cell layers. The vast majority are histologically benign, but the significant size they may attain can potentiate life‐threatening upper airway obstruction. All cases require the specialist airway skills of the pediatric anesthetist. This may be planned, in the case of antenatally diagnosed lesions, when the pediatric anesthetist is part of a multidisciplinary team involved in an EX utero Intrapartum Treatment (EXIT) or Operation On Placental Support (OOPS) procedure, or when a neonate is undergoing elective excision in the early neonatal period as definitive treatment. Alternatively the anesthetist may be called upon urgently to secure a compromised airway immediately postpartum when no antenatal diagnosis has been made. Furthermore, after elective surgical excision, airway compromise is possible, which may again require anesthetic intervention. The aim of this study is to report the authors’ experience in managing the airway in three cases of congenital cervical teratoma in the study institution over the last 24 months. These cases highlight the possible airway scenarios that may confront the anesthetist in the immediate postpartum, elective surgery and postoperative stages and the variety of techniques that may be employed in order to overcome the potential difficulties encountered.

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 cmH2O. 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 ≥ 60 cmH2O. 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.

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.

Traumatic aneurysm of the internal carotid artery in an infant: a surprise diagnosis

Isolated aneurysm of the extracranial section of the internal carotid artery has been reported in children but never, to our knowledge, in an infant. It can represent a major anaesthetic challenge with compromise of both airway and cerebral perfusion and the associated risks of rupture. We report on an 11‐month‐old infant, who had undergone an examination under anaesthesia of her nose and throat for epistaxis and gastrointestinal endoscopy due to apparent gastrointestinal bleeding shortly before presenting to us with signs of rapidly progressive upper airway obstruction. Emergency examination under anaesthesia revealed a large pulsatile mass in the posterior nasopharynx which, on subsequent radiological investigation, was revealed to be a large pseudoaneurysm of the right internal carotid artery, obstructing distal flow. An apparently minor episode of trauma had occurred around the time of the first nosebleed; she had allegedly fallen onto her face with a spoon in her mouth.