A child often presents for routine surgery with symptoms of an upper respiratory infection (URI) with a range of presenting signs most commonly including rhinorrhea, cough, and fever. Several large prospective studies have shown that the presence of URI symptoms may increase the incidence of laryngospasm by as much as fivefold and bronchospasm by 10-fold. This hyperreactivity of the airway generally persists for much longer after the symptoms have subsided, an observation supported by a number of clinical studies where sophisticated pulmonary functions were performed on human volunteers infected with varieties of respiratory pathogens (4). Diminished ciliary clearance of secretions under anesthesia may be a contributor to the atelectasis, lobar collapse, and desaturation seen in patients with respiratory infections undergoing anesthesia. A variety of factors guide the approach toward patients with a URI, including the patient age, severity of symptoms, color of the nasal discharge, operative procedure and medical history of the child. Most anesthesiologists agree that in the presence of fever, purulent secretion and productive cough, it is prudent to delay an elective surgery for 2 to 3 weeks (5). The airway anatomy of children supports increased caution in younger children, where airway resistance in peripheral airways remains high until the age of 5 (6).

Underlying medical conditions may be critical in predicting not only the potential for untoward reactions, but also in deciding when to accept increased risk of complications when faced with an uncertain benefit. An otherwise healthy child with runny nose and cough for a relatively small procedure not involving the airway generally presents little increased risk. A large number of children may have chronic lingering symptoms or repeated episodes of respiratory-like illnesses, and it is difficult to find a window during which these children are free of a runny nose or cough. In some cases, children would actually benefit from the planned surgical procedure such as placement of myringotomy tubes. Lower airway infections present a much greater risk of intra- and postoperative complications. Bronchitis, respiratory syncytial virus infection, and influenza often require 4 weeks or longer for adequate recovery of lower airway reactivity and secretion clearance.

The ex-premature child with reactive airway disease who has recent onset of rhinorrhea has a greater potential of developing perioperative respiratory complications. Younger children with smaller functional residual capacity and increased oxygen requirements tend to have a higher incidence of desaturation and breath-holding episodes. The type, extent, and urgency of planned surgical procedure are also major factors that affect the outcome.

Newer rapid tests for influenza viruses and Strep A antigen are available and can be performed at the bedside. Results are usually available in 15 to 20 minutes. None of the five currently available rapid influenza diagnostic tests are perfectly sensitive or specific. Up to 30% of patients with influenza may have a negative rapid test. Rapid tests are most useful for diagnosing influenza when the influenza virus is circulating at high levels in the community, at which time a positive test is likely to be true-positive, but a negative test does not rule out influenza.

Because survival of premature babies has improved during the last several decades, a large number of these patients need surgical procedures during their neonatal stay in the neonatal intensive care unit (NICU) and after discharge. Inguinal herniorrhaphy and surgery for retinopathy of prematurity are two such surgeries that are being performed with increased frequency and with a desire to expose these patients to the least amount of time in the hospital environment. These patients present unique challenges for anesthesiologists. Although all patients born before 36 weeks gestation are labeled as premature, “ex-premie” is not a homogeneous group. An infant born at 24 weeks who has spent weeks on a ventilator has different anesthetic concerns from a child born at 32 weeks who only needed supplemental oxygen for few days. Prolonged mechanical ventilation and endotracheal intubation, higher inspired oxygen concentration, and frequent respiratory infections during NICU stay may significantly affect normal lung and tracheal development. These insults affect alveolar growth, decrease capillary proliferation, affect ciliary clearance of secretions, and cause damage to lung architecture. These changes, labeled as chronic lung disease of childhood or bronchopulmonary dysplasia, continue to be of concern for the anesthesiologist for the first few years of the child’s life. Such infants also continue to display airway hyperresponsiveness.

Apnea is defined as absence of air exchange for more than 15 seconds, and in periodic breathing there are pauses in ventilation for 2 to 10 seconds (7). These may be associated with bradycardia and cyanosis, and this combination of apnea and bradycardia is frequently seen in premature infants who are emerging from anesthesia (8) and may extend for the first 24 hours while recovering. Most such episodes are self-limiting and respond to stimulation, but some patients may require mask ventilation and even intubation. The postconceptual age at which these events cease to be a concern and exactly what risk factors play a role are unanswered questions. In the absence of a large, randomized prospective study, the answers to such questions have been sought via meta-analysis performed by Cote et al. (9). They described the risk of apnea in the postoperative period to be inversely proportional to the postconceptual age at the time of anesthesia and surgery. The occurrence of an apneic episode is less than 5% after the postconceptual age of 48 weeks and less than 1% after the postconceptual age of 56 weeks. Anemia was the only consistent risk factor identified in this meta-analysis. Because the consequences of an apneic event happening at home may be devastating, they recommended that all ex-premature babies before the post conceptual age of 55 weeks should be admitted and monitored with pulse oximeter and apnea monitors for the first 24 hours. Intravenous caffeine (10 to 20 mg per dose, dependent on type of preparation) has been shown to reduce these events and is believed to be most effective when given at least 30 to 45 minutes before extubation (10).

The high incidence of inguinal hernia and the high risk of incarceration in premature infants make herniorrhaphy the most common surgical procedure in neonates and infants. Regional anesthesia (spinal or caudal) may offer advantages because there is no airway manipulation and minimal respiratory depression compared with potentially significant untoward results from inhaled and intravenous anesthetic agents. Studies have compared the incidence of apnea after spinal and general anesthesia in former premature infants. In a small prospective study conducted by Welborn et al. (11), no apnea was observed in patients who received only spinal anesthesia, whereas among patients who received general anesthesia, 31% had either prolonged apnea or apnea with bradycardia. Surprisingly, the spinal group who received ketamine for sedation had the highest incidence (89%) of postoperative apnea. However, spinal anesthesia for infants has certain limitations. It is technically difficult to perform and, at best, offers 60 to 70 minutes of surgical anesthesia. Other factors, including whether the hernias are bilateral, patient is male or female, the size of the defect, and the skill and experience of the surgeon, all play into the decision whether spinal anesthesia is preferred over general.

Occasionally, a murmur is detected on auscultation in an otherwise healthy child. Most often innocent murmurs are functional in nature (i.e., they are representative of a flow). Such murmurs, however, need to be distinguished from pathological murmurs. Innocent murmurs are always short, soft, systolic, and do not radiate. A harsh systolic murmur that radiates or changes its nature minimally with change in position is always indicative of cardiac pathology. Similarly, a diastolic murmur is never functional and should be investigated by a cardiologist who will usually rely on echocardiography and an electrocardiogram (ECG) to assist.

Obstructive sleep apnea (OSA) is a common problem in children characterized by frequent episodes of upper airway obstruction during sleep. Snoring is an extremely common finding and may be a sign of OSA. OSA is often associated with episodes of desaturation and hypoventilation of varying degrees and importance. Long-standing hypoxemia and hypercarbia in patients with chronic OSA can lead to pulmonary hypertension and eventually right ventricular failure. Patients suspected of having severe obstructive symptoms with possible cardiac effects should be evaluated with preoperative polysomnography, ECG, and echocardiography. Polysomnography can delineate the severity of OSA in terms of number of significant episodes associated with hypoxemia (described as apnea index). Residual anesthetic gases and sedating pain medications, especially the narcotics, can reduce tone in upper airway muscle thus increasing the potential for significant upper airway obstruction in the postoperative period. Signs may not appear until some time after the anesthesia and surgery, especially after the patient falls asleep. All patients with symptoms of OSA should be monitored (oximetry) until free of the effects of pain medications and residual anesthetic, whereas those patients with severe OSA should be monitored in the intensive care unit.

The prevalence of obesity in the United States and some other countries is continuously increasing (12). Obese children may have many of the same risk factors and conditions as obese adults, and have underlying conditions such as OSA (13), type 2 diabetes (14), exercise intolerance,
or present the anesthesiologist with a difficult airway to manage (i.e., difficult mask ventilation and difficult intubation). Obesity may affect both anesthetic management and outcome. Although these children appear bigger in size than their age-matched cohorts, their behaviors and responses are usually age appropriate. Anesthetic drug dosages should be calculated based on ideal body weight and not the actual body weight.

Children who have complex congenital heart defects require detailed evaluation of their cardiac anatomy. A recent note from his or her cardiologist and an echocardiogram report are usually helpful in highlighting a patient’s cardiac anatomy and function. In the presence of complex cardiac anomalies or because of their age or size, many patients undergo palliative repairs only. A significant number of patients will have residual cardiac defects and many patients may need noncardiac surgeries before their cardiac defects can be repaired. It is vital for the anesthesiologists to understand each patient’s cardiac anatomy and physiology because patients with similar anatomic diagnoses may have very different hemodynamic physiology. No single anesthetic drug or technique is ideal, and yet the challenge for the anesthesiologist is to minimize surgical stress while maintaining hemodynamic stability.

Examples of the need for customized plans are plentiful. Many patients (e.g., patients after Glenn shunt or Fontan procedures) require higher filling pressures to maintain cardiac output. Prolonged fasting and resultant dehydration may precipitate serious hypotension during induction in such patients. Patients who have undergone palliative correction of congenital cardiac defects may have serious deficits in myocardial function. Patients with intracardiac shunts may require manipulation of ventilation and inspired oxygen concentration to balance the pulmonary and systemic blood flow. High inspired oxygen concentration and hypocarbia, which can reduce pulmonary vascular resistance and improve pulmonary blood flow, may be desirable in some patients. However, in patients with large left to right intracardiac shunts (e.g., patients with ASD, VSD, or AV canal defects), high-inspired oxygen and hypocarbia may result in pulmonary overcirculation. Many patients who have undergone palliative repairs may be more prone to develop perioperative arrhythmias.

Not all patients with congenital heart defects require prophylaxis against bacterial endocarditis. Antibiotics should only be used in such patients according to the American Heart Association guidelines (Tables 17-1 and 17-2).

Many parents want to be present by the bedside until their child goes to sleep, either because they believe it will lessen the child’s anxiety or because of their own anxieties. In some cases, the parent believes that they can afford some degree of protection to their child whose well-being is now entrusted to strangers. In many children, presence of a parent can be a great help. In a randomized controlled trial, Kain et al. observed that children older than 4 years of age tend to benefit from parental presence (15,16). However, Palermo et al. demonstrated that parental presence had no impact on infant behavioral distress, parental anxiety, or satisfaction (17). If a decision is made to allow a family member to be present for induction, their role needs to be well defined and they need to be educated about events such as noisy breathing, rolling up of eyes, and excitement during induction. It can sometimes be very distressing for parents to watch such events. An operating room nurse should be designated to escort the parent out of the room as soon the child loses consciousness. If induction is expected to be stormy, if airway problems are anticipated, or if the patient requires a rapid sequence induction, most experts believe that parent presence should be avoided.

Midazolam remains the most commonly used drug for premedication (18). It is usually given orally in the dose of 0.3 to 0.6 mg per kg (max. 20 to 25 mg) and has an acceptable taste (bitter unless mixed with a strongly sweet diluent) and onset of action (15 to 20 minutes). Its short duration of action and easy reversibility with a specific antagonist, flumazenil, make it a drug of choice for the majority of pediatric patients. Most children become amnestic after 10 to 15 minutes, and some may become dysphoric with excitement or inconsolable crying. Very few children demonstrate any untoward respiratory or hemodynamic effects; however, the chance of undesirable physiologic side effects increases in patients with complicating medical conditions.

In some cases, administering anxiolytics and sedatives by the nasal route may be necessary, and will have an onset faster than the oral route. However, intranasal administration can be an unpleasant experience for the child because many medications produce a burning sensation on the nasal and pharyngeal mucosa and may have a very unpleasant taste. When given intravenously, midazolam, fentanyl, and ketamine each can produce sedation in a reliable, rapid fashion.

In the rare case of a combative, noncompliant patient, intramuscular injection of ketamine (3 to 10 mg per kg) is an option, and will have an onset of 10 to 20 minutes. Dosages at the higher end of the range can produce sedation within 5 to 10 minutes, but can delay emergence. Ketamine (intravenous formulation) has also been given orally alone or in combination with midazolam in difficult children. Any patient who receives ketamine is at risk for post-ketamine hallucinations and nightmares. The administration of a benzodiazepine with or immediately preceding ketamine decreases the incidence of these side effects.

Due to anatomic and physiologic differences, airway management of smaller children can be extremely challenging and requires special training and equipment. Understanding the differences between the adult and infantile larynx is essential for safe airway management. The child undergoes continued growth during the initial few years and achieves adult characteristics (but not size) by the time the child is about 8 years of age. Until that time, there are differences in location of the larynx relative to the tongue (more superior and therefore more difficult to visualize) and the angle of the vocal cords (making them less obvious on laryngoscopy). The narrowest part of an infant’s larynx has traditionally been believed to be the subglottic area at the cricoid cartilage. This has recently been challenged with the proposal that the narrowest portion may be the glottis (21). Unlike adults, positioning for intubation in small children does not require elevation of the head (classic sniffing position) because of their larger occiput (larger anterior-posterior dimension). The straight Miller or Wis-hippel laryngoscope blades are the most popular choices to facilitate visualization of the normally anterior infant larynx. After the age of 1 year, either straight or curved (e.g., Macintosh) blades can be used based on one’s own facility with these instruments. Uncuffed endotracheal tubes are usually employed for intubation in neonates, infants, and smaller children. However, cuffed endotracheal tubes may be necessary and can be used safely in patients where higher airway pressure may be required to ventilate the patients.

Difficulty in securing an airway can be anticipated in patients with obvious predisposing factors such as micrognathia, midface hypoplasia, enlarged tongue, limited neck mobility, and facial clefts. However, more subtle signs such as retrognathia in a newborn can easily be missed if the profile of the patient’s face is not carefully examined. The true incidence of an unanticipated difficult airway in pediatric patients is unknown. Employing the Mallampati classification (opening mouth and grading according to how much of the oropharyngeal structures can be seen), which has useful but not absolute predictive value in adults, is impractical in neonates and smaller children. In cases where a difficult airway has been encountered, a detailed note should be written in the patient’s medical record, the parents should be given a copy should be made aware of the situation, including a description of what successful intervention was used. A recent trend is to issue engraved identification bracelets to patients who have a difficult airway to notify health care providers of the potential situation should an emergency arise.

ECG, blood pressure, pulse oximetry, temperature, end-tidal carbon dioxide, and inspired oxygen concentration monitoring form the basic minimum listed in the practice standards of the American Society of Anesthesiologists (ASA) (23) in the United States. Many other countries have advisory or legal bodies that have made similar recommendations. In addition, many institutions routinely monitor inspired and end-tidal concentrations of anesthetic gases, airway pressure, tidal volume, and neuromuscular function.

During the perioperative period, smaller children are at a higher risk for developing hypothermia. Nonshivering thermogenesis is the major source of heat production in neonates. In response to cold, norepinephrine is released that stimulates catabolism of brown fat. Neonates and smaller children have a larger body surface area: body weight ratio. During anesthesia vasodilatation, lack of shivering, and suppression of nonshivering thermogenesis result in rapid loss of heat. Cold intravenous fluids, dry respiratory gases, cold irrigation fluids, and dry cold air of the operating room increase heat loss tremendously. Mild hypothermia of 1°C to 3°C is common after surgery. Moderate or severe hypothermia, however, can have significant consequences leading to increased oxygen consumption, acidosis, platelet dysfunction, increased surgical bleeding, and increased infection rates (24). Hypothermia also may affect drug metabolism, resulting in prolongation of effects of drugs (e.g., the neuromuscular blocking agents). Thus, care should be taken to monitor and maintain core temperature in the perioperative period. Simple measures such as wrapping exposed areas of the body with plastic wrap, increasing the environmental temperature and humidity, using low fresh gas flow, and employing a heat and moisture exchanger (passive humidifier/filter) on the airway can help achieve this. For prolonged and extensive surgeries, forced air warmers, warming blankets, fluid warmers, and overhead radiant heaters are often required.

The function of the neuromuscular junction can be monitored by stimulating directly over a superficial motor nerve with a defined frequency and strength. Monitoring is especially recommended in smaller children and neonates because they are believed to be more sensitive to the effects of neuromuscular blocking agents. In addition, pharmacokinetic differences result in wide variation in duration of action. Dosing of muscle relaxants should be based on monitoring of the neuromuscular junction rather than on the time interval.

Invasive monitoring is usually reserved for patients undergoing a procedure where hemodynamic instability is expected.

Direct intraarterial blood pressure monitoring is often used in patients where a large blood loss is anticipated. Although not supported by study, expected loss of 50% of the calculated blood volume or greater has become the threshold for many pediatric anesthesiologists to elect to use continuous arterial pressure monitoring. The radial artery is the most frequently accessed site; however, the dorsalis pedis, posterior tibial, femoral, and ulnar arteries can also be cannulated for a short period of time with minimal risk of ischemia of the limb. Positioning the catheter in the artery can be challenging, especially in smaller neonates. Doppler-guided needles have recently been made available, and small portable ultrasound units can help locate the vessels and thus avoid a surgical cut down.