Most anesthesia-related morbidity is respiratory in nature. There is an increased incidence of respiratory adverse events in children who have a current or recent upper respiratory tract infection (URTI). Complications include bronchospasm, laryngospasm, desaturation, coughing, and stridor. It is clear that children with current severe URTI, systemic illness or signs of lower respiratory tract infection should have elective surgery postponed. A high risk of perioperative adverse events is present in the first 2 weeks after a URTI (Von Ungern-Sternberg et al. 2010). Children with URTI greater than 2 weeks prior to surgery have a low risk of perioperative respiratory events, and surgery can be undertaken. As children have six or more URTI a year, it is difficult to find a window of opportunity when they are free of URTI. For children with mild current or mild recent URTI less than 2 weeks prior to surgery, it may be appropriate to proceed for practical reasons. This approach accepts that there is an increased risk of adverse respiratory complications. Other risk factors for perioperative respiratory complications include underlying asthma, chronic lung disease of prematurity, or other chronic lung disease such as cystic fibrosis. Atopy, a strong family history of atopy, and exposure to second-hand smoking have also been found to be associated with increased risk (Von Ungern-Sternberg et al. 2010). For these children respiratory function should be optimized prior to elective surgery, and a lower threshold for postponing surgery in the presence of a URTI should be exercised. In particular, asthma should be well controlled before surgery. In children with underlying cardiac disease or chronic lung disease of prematurity, a more conservative approach is warranted as even minor respiratory complications can have potentially catastrophic consequences.

Any decision whether or not to proceed when a child has a URTI needs to involve informed consent with the parents as well as discussion with the surgeon. Other factors such as the age of the child and the nature and urgency of the surgery need to be considered. The threshold for cancellation may need to be lower in hospitals that do not look after pediatric patients on a regular basis or that do not have backup to manage complications. Anesthesia management should be tailored to minimize risk. An anesthetist with ongoing experience in pediatric anesthesia is important in minimizing risk. See Table 2.2.

Children with congenital heart disease are another group at risk of cardiorespiratory complications in the perioperative period. This group should be referred for review. Echocardiography should be sought to assess ventricular systolic and diastolic function, intracardiac shunts, valvular dysfunction, and pulmonary hypertension. The child with a previously undiagnosed murmur presents a different challenge. Generally, children with asymptomatic murmurs who are active and keep up with their peers without shortness of breath, fatigue, cyanosis, and without difficulty feeding or failure to thrive (infants) will tolerate general anesthesia for minor surgery. Any children who are symptomatic or undergoing major surgery should be reviewed prior to surgery. All children with high-grade murmurs, diastolic murmurs, or pansystolic murmurs should also be reviewed prior to surgery. Other signs, such as reduced femoral pulses or signs of cardiac failure should be sought. Consideration should be given to indications for antibiotic prophylaxis in children with cardiac lesions.

Underlying syndromes can present multiple challenges for anesthesia. These include airway anomalies, respiratory disease, and cardiac, musculoskeletal, and renal abnormalities. A group of syndromes are associated with difficult airway and difficult intubation. These include Pierre Robin sequence, Treacher Collins syndrome, Beckwith-Wiedemann syndrome, the mucopolysaccharidoses (e.g., Hunter syndrome, Hurler syndrome, Sanfilippo syndrome), and Goldenhar syndrome, also known as Oculo-Auriculo-Vertebral (OAV) syndrome. Characteristic airway features of many of these syndromes are small mouth opening, small and recessed mandible, and a relatively large tongue. In the mucopolysaccharidoses, tissue deposits in the airway and elsewhere increase over time such that the airway becomes progressively more difficult to manage. Many syndromes have associated congenital cardiac anomalies which may or may not have required surgery. Neuromuscular and musculoskeletal abnormalities can present challenges for vascular access and positioning. Abnormalities involving the chest wall can result in restrictive lung defect and respiratory failure. Bulbar dysfunction can lead to swallowing difficulties and a tendency to recurrent aspiration further compromising respiratory function. Generalized muscle weakness or myopathy leads to sensitivity to the respiratory depressant effects of sedative, anesthetic, and analgesic agents. Some patients may require postoperative ventilation, or noninvasive respiratory support, or at the very least continuous pulse oximetry and apnea monitoring.

Malignant hyperthermia (MH) is an autosomal dominant pharmacogenetic condition. When susceptible patients are exposed to suxamethonium and volatile anesthetic agents, a hypermetabolic cascade commences in skeletal muscle. This results in rhabdomyolysis, hyperthermia, and lactic acidosis with hypercarbia. The condition is often fatal when not recognized and treated promptly. Genetic testing will provide a diagnosis in 50 % of cases (Ungern-Sternberg and Habre 2007). In vitro contracture testing of muscle biopsy is the diagnostic test. However, this can only be performed in older children because of the size of the muscle biopsy required. A trigger-free anesthetic should be used in all patients with a diagnosis of MH or with a family history of MH. Central core disease, multi-minicore disease, nemaline rod myopathy, Evan’s myopathy, and King-Denborough syndrome are associated with malignant hyperthermia (MH). The muscular dystrophies (Duchenne muscular dystrophy and Becker dystrophy) can result in rhabdomyolysis with exposure to volatile anesthetic agents and suxamethonium. Hyperkalemic cardiac arrest can result. Volatile anesthetic agents should be avoided or used with extreme caution in these patients. Suxamethonium is contraindicated.