Historical reports of outpatient surgery date back to the early twentieth century, when Nicholl reported nearly 9000 operations on ambulatory children at Glasgow’s Royal Hospital for Sick Children (Nicholl, 1909). Other early reports from the United States soon followed, but it was not until the 1970s that studies looking at same-day surgery from a systems perspective were published. In addition to examining the patient population, complication rates and surgical procedures, these reports began to look at issues such as cost and delivery of care, as well as the optimization of the nursing and support staff, organization, and physical plant for outpatient surgery. Attention to these details continues to play a central role in the increased use and success of outpatient surgery. In the current economic climate of health care in the United States, there is and will continue to be a major emphasis on cost savings. In addition to the economic advantages of savings on hospital resources, a primary driving force in the popularity of outpatient surgery is satisfaction of the patient’s parents. There are obvious advantages for many parents and children to avoid overnight hospitalization and to have the child back in a familiar home environment on the same day. The decisions that are made in planning the outpatient system will have a major impact on how parents perceive ease of use and quality of care of the entire system, and, as a result, its success. Factors that are not medical at all (e.g., ease of parking, efficiency of check-in procedures, waiting time, parental presence during induction of anesthesia, and early admission to the postanesthetic recovery unit [PACU]) may make impressions on the parent that are equal to the obvious medical issues, such as complication rates, management of postoperative analgesia, postoperative nausea and vomiting (PONV), and rapid return to the preoperative mental state.

Procedures and patients amenable to outpatient surgery and anesthesia

Many operative procedures are well suited to be performed on pediatric outpatients and all share several common characteristics. They all are peripheral procedures that do not involve major violation of a body cavity. They all have limited duration, generally lasting less than 2 hours, and have minimal or moderate amounts of postoperative pain that can easily be managed after discharge from the PACU with oral analgesics, or by either a single-injection regional block placed at the time of surgery or continuous regional analgesia at home. They do not result in major physiologic perturbations or blood loss, nor do they disturb the ability to take oral fluids and nutrition in the immediate postoperative period. They do not require postoperative monitoring beyond the capability of the parents and home. Commonly performed outpatient procedures are listed and categorized in Table 34-1.

TABLE 34-1 Operations Commonly Performed as Outpatient Surgical Procedures by Specialty

Specialty	Procedures
Otolaryngology	Myringotomy and ventilating tubes, adenoidectomy (see text), tonsillectomy (see text), frenulectomy, branchial cleft cysts, endoscopic sinus surgery, examination under anesthesia including some bronchoscopy
Ophthalmology	Examination under anesthesia, strabismus repair, nasolacrimal duct probe, intraocular lens implantation, trabeculectomy
General pediatric surgery and urology	Herniorrhaphy and hydrocelectomy, orchiopexy, uncomplicated hypospadias, cystoscopy and cystoscopic surgery, circumcision, esophogoscopy, lumps and bumps
Gastroenterology	Endoscopy
Plastic surgery	Cleft lip and some cleft palate repair, placement of tissue expanders, scar revision, minor reconstructive procedures (otoplasty, septorhinoplasty, etc.)
Orthopedics	Hardware removal, casting, percutaneous tenotomy, arthrograms Percutaneous pinnings and simple OFIF
Radiology	Imaging studies, radiation therapy
Dentistry	Extractions, restorations, examinations Nerve treatments, crowns, sealants, and fillings

Contraindications for outpatient anesthesia

There are few firm contraindications to outpatient surgery for amenable procedures, but there are some patients who have medical issues that make it advisable to consider an overnight (“23-hour”) admission rather than discharge on the day of surgery. In the majority of these cases, monitoring is required because of anesthetic-related risks or because of exceptional risks related to the operative procedure or postoperative care in susceptible individuals.

Expremature Infants and Apnea

The risk of postanesthetic apnea in former premature infants has been well described since the early 1980s, when Liu et al. (1983) published the first prospective study of premature infants anesthetized between 41 and 46 weeks’ postconceptional age (postconceptual age equals the gestational age at birth plus an infant’s current age in weeks). The authors compared a group of premature infants with a control group of term infants of similar ages. The incidence of apnea, defined as pauses in breathing lasting greater than 15 seconds, was 20%. Subsequent studies have approximated this incidence, although some have placed the at-risk period as far out as 60 weeks’ postconceptual age (Welborn et al., 1986; Kurth et al., 1987; Warner et al., 1992). It is now established that infants born before 36 weeks’ conceptional age are at some risk of apnea after general anesthesia. It appears that this risk is because of immaturity in the brainstem’s control of breathing after exposure to general anesthetics, and there may be similar risks after exposure to sedative-hypnotic agents and neuroleptic agents such as ketamine. Numerous studies have tried to define the period of susceptibility in the at-risk population. Several investigators have stratified the risk according to postconceptual age and gestational age at birth, and a meta-analysis of eight studies has reported that the postconceptual age required to reduce the risk to less than 1% with 95% confidence was 54 weeks in infants born at 35 weeks’ gestational age and 56 weeks in those born before 32 weeks’ gestation (Malviya et al., 1993; Coté et al., 1995). In this meta-analysis, anemia was also associated with increased apnea risk, particularly in infants older than 42 weeks’ postconceptual age. The patients in the numerous studies that were included in this meta- analysis may not have all been comparable in terms of underlying state of health, so these data (as in all meta-analyses) must be approached with some caution. Several investigators have suggested that the use of regional anesthesia may eliminate the risk, and a few even advocate discharge of these patients on the day of surgery if no other agents have been administered (Veverka et al., 1991; Webster et al., 1991; Sartorelli et al., 1992; Krane et al., 1995). However, uncontrolled case reports of apnea after spinal anesthesia have been published (Watcha et al., 1989; Tobias et al., 1998). Because these are case reports and there were no control pneumograms, it is unknown if the apnea was related to the anesthetic or not, but these reports have still prompted most clinicians and consultants to continue to recommend admission and monitoring of these patients for 24 hours after any anesthetic. Krane et al. (1995), in a prospective randomized controlled study, compared former premature infants receiving general or spinal anesthesia with preoperative and postoperative impedance respirometry, oxygen saturation, and electrocardiography (ECG). In this small sample of 18 patients, no central apnea differences were detected, but the group receiving spinal anesthesia had fewer desaturations and bradycardic events than those receiving general anesthesia. Caffeine, which has a long history of effective use in apnea of prematurity, has also been suggested to increase central respiratory drive after anesthesia in these patients, although it is still not commonly used (Welborn et al., 1988, 1989).

Obstructive Sleep Apnea

One of the most common indications for tonsillectomy is upper-airway obstruction during sleep. In many centers, obstructive sleep apnea (OSA) accounts for 50% or more of all children who come for tonsillectomy and adenoidectomy (Messner, 2003). These children may have abnormal ventilatory responses to both hypoxia and hypercarbia as a result of the chronic exposure to hypoxic and hypercarbic conditions during sleep (Strauss et al., 1999; Kerbl et al., 2001). These responses can take up to several weeks to revert to normal after resolution of the obstruction. There are concerns, therefore, about the ability to maintain adequate ventilation and oxygenation in the period immediately after the exposure to general anesthetics and to opioids given for postoperative analgesia. A study of 15 otherwise healthy children, ages 1 to 18, with mild OSA used preoperative and postoperative pneumograms to assess respiratory status on the night after adenotonsillectomy. Nine of these children received a halothane-based anesthetic, and six received a fentanyl-based technique. The number of obstructive events decreased, and the nadir of oxygen saturation improved from 78% to 92%. The authors concluded that in cases of mild OSA without other underlying disorders, intensive postoperative monitoring is not necessary (Helfaer et al., 1996). In another group of 134 children selected for outpatient tonsillectomy, 83% of whom carried the diagnosis and indication for surgery for OSA, 11 (8.2%) were admitted for inpatient observation after experiencing respiratory problems in the postanesthetic care unit (Lalakea et al., 1999). These patients as a group were significantly younger than those discharged home (an average age of 4 vs. 6.3 years). Preoperative evaluation and assessment of OSA was not described. Most otolaryngologists consider significant (as opposed to mild or moderate) OSA to be a relative contraindication to outpatient management of adenotonsillectomy, especially in children younger than 3 years of age, although in one small study the postoperative complications in these younger children were not related to obstructive events (Slovik et al., 2003). Those investigators suggested that the severity of OSA, rather than a patient’s age, may be a more predictive factor, but this is in conflict with other reports that recommend that an age younger than 3 years should be considered an independent discriminator (Shott et al., 1987; Biavati et al., 1997). One large retrospective analysis of 2315 patients younger than 6 years of age undergoing adenotonsillectomy for OSA found a higher rate of respiratory complications in those younger than 3 years (9.8% vs. 4.9%) (Statham et al., 2006). The only criterion that appears to be unequivocally accurate in the diagnosis and stratification of severity in OSA is polysomnography; neither the history nor pulse oximetry alone is specific or sensitive enough (American Thoracic Society 1996; Schechter, 2002; Subcommittee on Obstructive Sleep Apnea, American Academy of Pediatrics, 2002). In the absence of objective data, it is worthwhile to elicit a history of significant snoring or sleep-disordered breathing during the preoperative interview with the parent. Even though such historical data may not be accurate in all cases, it serves to alert the anesthesiologist to the potential for problems (Sinha et al., 2008).

Recent data on opioids in the patient with chronic hypoxemia are particularly relevant to the child with OSA, whether the child is to undergo tonsillectomy or another surgical procedure. In an animal model, rats exposed to chronic hypoxic conditions had greater respiratory sensitivity to opioids, exhibiting diminished respiratory drive (Moss et al., 2006). Confirming these animal data, children who experienced significant hypoxia during sleep had lower opioid requirements to achieve analgesia after tonsillectomy (Brown et al., 2006). In this prospective study of 22 children with OSA undergoing tonsillectomy, the opioid dose required to achieve equal analgesic scores on a behavioral pain scale was directly correlated with the nadir of their oxygen saturation on the preoperative polysomnogram. Those with the lowest saturations required the least opioid, demonstrating that chronic recurrent hypoxemia during sleep was associated with increased analgesic sensitivity to morphine. The key implication is that not only are ventilatory responses to hypoxia and hypercarbia with opioids blunted, but actual analgesic requirements are less, and lowering opioid and other sedative medication doses still results in adequate analgesia while potentially reducing the risk of untoward effects.

Preoperative evaluation and planning

The evaluation of outpatients for surgical procedures presents a significant organizational challenge to the anesthesiologist. Because one of the primary goals of outpatient surgery is both efficiency and rapid throughput, there is a great disincentive to require preoperative visits before the day of surgery itself. At the same time, an efficient system demands an absolute minimum of cancellations on the day of surgery. Such pressures put both the anesthesiologist and the system as a whole at significant risk of proceeding with cases in which the patient may not be optimally prepared for surgery and anesthesia. There is also the stress of “production pressure”—the urgency to move patients rapidly through the preoperative queue and into the operating room on schedule. This, too, is in competition with the need to provide the best and most complete evaluation and care of the patient. In order to avoid these situations, a system of preoperative screening must be instituted that provides the most accurate, up to date, and complete information so the anesthesiologist may make well-informed decisions about patient management. Fortunately, both technological and nontechnological aids exist to streamline this process.

The implications of cancellation, particularly on the day of surgery, go far beyond the efficiency of the operating room. A survey by Tait et al. (1997) found that nearly half of parents whose children’s operations were cancelled on the day of scheduled surgery missed a day of work, and about half of these went unpaid as a result. Many drove long distances to get to the hospital, and nearly 25% were frustrated or angry as a result of the cancellation. A small number of dissatisfied or angry parents can have an adverse impact on the success of an outpatient surgery program well out of proportion to their numbers, and great attention must be paid to minimizing these events by using systems that work effectively.

In many cases, a preoperative visit to the anesthesiologist is neither practical nor necessary. Because the majority of children who come for same-day surgery are relatively healthy, screening tools that employ methods such as telephone interviews and self-reporting can often be employed. Coordination with the surgeon’s office may reduce both redundancy in paperwork and repeated questioning of the patient’s family. The efficiency in combining surgical, anesthetic, and nursing evaluations can be greatly enhanced if a computerized record is used. With these systems, which are finally beginning to reach maturity after years of development, data from one evaluation can automatically populate another linked database; however, at times implementation of these systems still remains limited, and lack of universal interoperability and poor interface and database design remain major impediments to their acceptance. Nevertheless, at the start of the second decade of the 2000s, progress is being made and it can be expected that increased use of electronic medical records will greatly streamline the evaluation process. Even in the majority of institutions, where paper records still remain the standard, systems using secure e-mail, facsimile, or even common forms can be designed to eliminate redundancy. The elimination of needless paperwork or data entry can be a great aid in increasing patient throughput, as well as reducing the frustration of staff and parents alike.

The initial step in preoperative planning and evaluation begins when the surgeon books the case. This is the first opportunity for the system to alert the anesthesiologist of any unusual conditions or underlying illnesses that the patient may have. A short list of check-boxes on the booking form suffices and need not have any great detail. This information can be reviewed by an anesthesiologist (or, in an electronic system, automatically trigger an alert to a consulting anesthesiologist) to detect any cases that might benefit from especially extensive consultation or planning before the day of surgery.

The surgeon’s office, because it is the initial contact point of the patient’s family with the perioperative system, also provides an excellent opportunity to present the parents with introductory information about the anesthetic. A pamphlet describing generalities such as the role of the pediatric anesthesiologist in caring for the child, fasting instructions, contact numbers, and other information specific to the hospital or outpatient surgical center can be a useful reference for the family. Having a written reference for fasting guidelines is especially helpful, because lack of adherence to these instructions is a common cause of case delay or cancellation. The language should be clear and uncomplicated, and a place for the actual times that the child in question should cease eating and drinking should be provided to eliminate confusion and misinterpretation. It is advisable to set the fasting time based not on the scheduled time of operation but rather on the time of arrival at the preoperative unit. This permits the case to go forward early if the operating room runs ahead of schedule. Parents should be given a number to call both for questions about the anesthetic that they feel cannot wait until the preoperative assessment, and for consultation with an anesthesiologist should an intercurrent illness develop between the time of the visit to the surgeon and the day of surgery.

A preoperative visit to the surgeon alone, however, will not optimize the preoperative evaluation process for the anesthesiologist or for the same-day surgery process as a whole. A case-control study of pediatric outpatient cancellations found that 10% of all day surgery patients at a children’s hospital were cancelled on the day of surgery, and half of those were for preventable reasons. Cancelled patients who had inadequate preoperative preparation were more likely to have been seen only in the surgeon’s office and not in the hospital’s preoperative program (Macarthur et al., 1995). It is clear that further screening is optimal to address general medical and anesthetic concerns.

Background

A short telephone interview with the patient’s parent before scheduled surgery, whether conducted by the anesthesiologist, a physician’s assistant, or a nurse practitioner, can be not only a source of clinical information about the patient and about the parent’s concerns, but can also forestall unanticipated problems that can cause delays, cancellations, or complications on the day of surgery. Knowing in advance, for example, that a child with asthma had a mild upper respiratory infection (URI) the week before surgery, can allow the anesthesiologist to prescribe a short preoperative course of steroids with ample time for the drug to take effect. The child who has sickle cell disease with an active URI, on the other hand, might have surgery postponed, thus saving the parents a trip to the hospital and allowing the schedule to be rearranged before the day begins. A well-organized system for conducting these calls should be established, so patients are not missed and communications with the anesthesiologist scheduled to care for a particular patient can be easily accomplished. It is important to organize the system so that calls are most effective. A study of over 5000 patients conducted at National Children’s Hospital in 1992 found that calls made during the evening were far more likely to successfully reach the parents—not an unexpected finding (Patel and Hannallah, 1992). In Great Britain and in some hospitals in the United States, preoperative clinics rather than telephone screening are used, but this may necessitate an additional visit by the family. The inconvenience may outweigh the advantages of a face-to-face visit for some families, and success may be predicated on ease of use of the system. Preoperative screening and evaluation can also improve throughput on the day of surgery, particularly if there is a long list of short cases, such as myringotomy and ventilation-tube placement. The duration of those cases is so short that the time it takes to do a preoperative evaluation may be longer than the operative time. Saving even 10 or 15 minutes per hour might allow the team to perform an additional operative procedure each hour.

Other methods of communication, including secure websites and e-mail, have been used for similar purposes. The ability for a family to access a secure server and enter preoperative interview information will likely become increasingly attractive in coming years. Although the personal interaction with a knowledgeable professional can never be replaced, certain “boilerplate” data can be entered with great efficiency in this manner, permitting rapid and efficient review by the anesthesiologist. Intranet-based kiosks at the hospital, where patients’ families can use either keyboard or touch-screen technology to enter information that is now entered on paper questionnaires at the time of admission, will become increasingly important modalities as hospitals move from paper-based records to digital ones.

It is particularly important that reports of previous operative procedures or consultations by specialists be made available to the anesthesiologist during the preoperative assessment. A computerized repository of this information is the best solution, because it allows immediate access from any location. However, many institutions have not yet migrated to completely digital medical records, and legacy data from the paper chart must be entered into the electronic chart as scanned documents. Unless all electronic documents are properly tagged or archived in a appropriate folders, they may be difficult to locate. Knowledgeable database professionals, in consultation with the anesthesiology department, must carefully determine a scheme for labeling and retrieving archived documents in advance. If an electronic medical record is not in place, a day-surgery coordinator should have the responsibility of ensuring that necessary outside and internal records are readily available the day before surgery in order to avoid delays. Such information must be immediately accessible to the anesthesiologist on the day of surgery as well.

In some locations, it is common for a child’s pediatrician to be responsible for “clearing” the child for surgery. This can be a considerable help, because the pediatrician often has the best knowledge of the child’s underlying illnesses and conditions. The pediatrician, however, often has little understanding of the issues that are of greatest concern to the anesthesiologist and may actually miss or ignore problems that can impact anesthetic management, to the detriment of the preoperative evaluation process. The anesthetic implications and preoperative optimization of airway anatomy and function, gastroesophageal reflux, upper respiratory illness, and asthma, as well as of syndromes and chronic conditions such as Trisomy 21 and the former premature infant, all may be underappreciated by pediatricians who do not work in the operating room or administer anesthetics and have usually had little or no training in perioperative medicine (Fisher, 1991). Several recent reviews (written by pediatric anesthesiologists) in the pediatric literature have discussed the preoperative screening process and what the pediatrician needs to know about preparing the child for anesthesia (Fisher, 1991; Fisher et al., 1994; Maxwell et al., 1994; Section on Anesthesiology, 1996). If a hospital or surgery center relies on pediatricians as a major link in the preoperative assessment chain, pediatricians must be familiar with this literature and should have ongoing communication with their anesthesiology colleagues. Collaborative efforts, such as continuing medical education conferences and residency training about these topics, can reap significant rewards.

Policies on preoperative testing have been completely reassessed in recent years, and abandonment of the routine use of tests has become the norm. This is driven by both the growing number of studies that demonstrated little or no value in such testing, as well as by economic concerns that mandate the elimination of unnecessary expenditures.

Urinalysis

A 1990 study of nearly 500 children scheduled for elective surgery found abnormalities in 15% of children; however, more than 80% of those were historically known, clinically insignificant, or false positives. The authors concluded that preoperative urinalysis should not be routinely performed on healthy children for preoperative assessment (O’Conner and Drasner, 1990).

Hematocrit and Complete Blood Count

Unless a surgery is expected to result in significant blood loss (highly unlikely for outpatient surgery), the complete blood count (CBC) screening has little or no value (Roy et al., 1990, 1991; Hackmann et al., 1991). Several studies have demonstrated that the presence of mild to moderate anemia has little to no effect on the conduction of anesthesia or outcome in children undergoing same-day surgical procedures. The presence of anemia in former premature infants of fewer than 54 weeks’ postconceptual age has been found to correlate with an increased risk of postanesthetic apnea, and screening for anemia in this population may detect those at increased risk (Welborn et al., 1991). It is not known, however, if the anemia is the cause of increased apnea or only an associated finding. There are no data to determine whether correction of anemia in these patients reduces the risk of apnea. All former premature infants who are at risk should be admitted for postoperative monitoring in any case, thus screening may not alter clinical practice. Children with sickle cell disease (not trait) need to have their hemoglobin level measured, because both management and outcomes of these patients are dependent on an adequate level of hemoglobin A or F (see the following section).

Sickle Cell Testing

In many states, newborns in at-risk populations are screened for sickle cell disease, thus the sickle cell status of all infants and children in those locations is known. In locations where such newborn screening is not universal, it is prudent to obtain sickle cell testing in any infant or child under the age of 3 years of at-risk ethnicity whose status is unknown. Children older than this are likely to have had symptoms if they are affected. In children who do have sickle cell disease, a preoperative hemoglobin level is mandated to determine the need for preoperative transfusion. A large multicenter trial found that simple transfusion, if the hemoglobin was less than 10g/dL, is as effective as exchange transfusion in these patients (Vichinsky et al., 1995) (see Chapter 36, Systemic Disorders). One study has reported that minor surgical procedures like those usually performed on outpatients could be safely performed in patients with sickle cell disease without preoperative transfusion; complication rates were significantly higher in children undergoing abdominal, thoracic, or airway procedures (Griffin and Buchanan, 1993). However, sickle cell trait, which usually does not cause any symptoms or illness, has rarely been associated with the complications of surgery and anesthesia, and hemoglobin determination in these patients is unnecessary (Konotey-Ahulu, 1969; McGarry and Duncan, 1973; Atlas, 1974; Gibson and Love, 1974).

Heart Murmurs and Cardiology Consultation

At least 25% of healthy children have an audible heart murmur at some time during childhood, and the question of when to refer a child to a pediatric cardiologist for the evaluation of a new murmur is often raised during the preoperative evaluation. The vast majority of these are functional (“innocent”) murmurs, not associated with any structural heart disease. Innocent murmurs are soft (less than grade 3), blowing, and loudest along the left sternal border. They tend to decrease or disappear during inspiration. Most congenital heart lesions appear before the first several months of life, so an asymptomatic murmur in an older child is less likely—but not entirely impossible—to be significant. Exceptions include atrial septal defects, small ventricular septal defects, coarctation of the aorta, some valvular lesions that have no hemodynamic symptoms during normal activity, and in rare instances, other lesions. The ability of a pediatric cardiologist to distinguish between a functional murmur and one caused by a structural heart lesion by examination alone was evaluated and found to be high, so more extensive (and expensive) evaluation, such as echocardiography, is rarely necessary (Newburger et al., 1983). If the child is older than 6 months of age, without any symptoms referable to the cardiac system, most skilled clinicians should be able to evaluate these murmurs and rule out hemodynamically significant congenital heart disease. Cardiomyopathy can also bring on a new murmur, so a previously undetected murmur accompanied by symptoms suggestive of impaired myocardial performance or irritability, such as dysrhythmias, especially if it follows a viral illness, should be evaluated by a cardiologist.

Children with some congenital heart lesions require antibiotic prophylaxis for the prevention of endocarditis when undergoing operations during which they will be at risk. In 2007 there was a major revision in the recommendations for antibiotic prophylaxis of congenital heart disease that significantly reduced the number of conditions that require treatment (Box 34-1). The current American Heart Association recommendations are available online at http://circ.ahajournals.org/cgi/reprint/CIRCULATIONAHA.106.18309.. It should be noted that for optimal treatment, the intravenous (IV) antibiotic should be administered 30 minutes before the procedure’s start, which can pose a considerable problem in day surgery when an IV port is not present before induction. Antibiotic prophylaxis is no longer recommended for routine procedures of the gastrointestinal (GI) or genitourinary (GU) tract, but it is still advisable for dental and oral procedures during which there is manipulation of the gingivae and periapical region of the teeth or perforation of the oral mucosa, procedures of the respiratory tract, and procedures on infected skin or musculoskeletal tissues. For these procedures, oral antibiotics can be given 1 hour before the procedure, thereby eliminating the problem of timing. When IV antibiotics are desired, our current practice is to begin their administration as soon as IV access is obtained.

Box 34-1 AHA Recommendations for Antibiotic Prophylaxis for Endocarditis: Cardiac Conditions Associated with a High Risk of Adverse Outcome

Prosthetic cardiac valve

Previous history of infectious endocarditis

Unrepaired cyanotic congenital heart disease, including palliative shunts or conduits

Completely repaired congenital heart disease with prosthetic material or devices, whether placed surgically or by catheter intervention, during the first 6 months after the procedure

Repaired congenital heart disease with residual defects or shunts at the site or adjacent to the site of a prosthetic patch or prosthetic device (that inhibit endothelialization)

Cardiac transplant recipients who develop cardiac valvulopathy

Adapted from Wilson et al.: Prevention of infective endocarditis: guidelines from the American Heart Association, Circulation 115:1736–1754, 2007.

Underlying illnesses and complicating factors

There are numerous underlying conditions that exist commonly in relatively healthy children that do not preclude outpatient surgery but have implications regarding the preoperative preparation and anesthetic management.

Upper Respiratory Tract Infections

Probably the most common problem to confront the anesthesiologist caring for children in outpatient surgery is the child with a URI. Viral respiratory tract illness is virtually ubiquitous in children, particularly during the winter months when close indoor contact in schools and daycare facilities with other children with colds is impossible to avoid. The average preschool child contracts between 6 and 8 URIs per year. Both upper and lower respiratory tract viral infections can increase airway inflammation, irritability, and respiratory tract secretions by mechanisms as diverse as increased production and decreased degradation of tachykinins and other neuropeptides, viral induced damage to M2 muscarinic receptors in the airways leading to vagal-mediated hyperreactivity, and increased volume and viscidity of airway secretions causing subsegmental atelectasis (Empey et al., 1976; Dusser et al., 1989; Williams et al., 1992). Increased airway reactivity and hyperresponsiveness occur in the lower airways even in patients with respiratory viral illness clinically limited to the upper airway and even in those with no history of asthma (de Kluijver et al., 2002). After the apparent resolution of the URI, increased airway hyperresponsiveness and irritability may persist for as long as 8 weeks (Empey et al., 1976; Empey, 1983). In children with underlying respiratory disease, such as asthma, bronchopulmonary dysplasia, or other chronic lung diseases, these responses may be further exaggerated. Other risk factors that may be associated with more serious or common complications are age younger than 1 year and sickle cell disease (Cohen and Cameron, 1991). In what is perhaps one of the most comprehensive investigations of URI and anesthesia, 1078 infants and children were prospectively studied (Tait et al., 2001). Independent risk factors for respiratory complications were endotracheal intubation, history of prematurity, reactive airways disease, parental smoking, airway surgery and nasal congestion, and the presence of copious secretions. Of interest is that a history of prematurity was a risk factor even in children who were several years old and no longer had ongoing problems referable to their premature birth.

Numerous studies have documented that children who either have URIs or who have recently recovered from one have more minor airway complications during or after anesthesia compared with healthy children. Mild oxygen desaturation and coughing, as well as more potentially serious complications such as bronchospasm, laryngospasm, and respiratory failure are particularly likely to occur if the airway is stimulated. Tait and Knight (1987) prospectively studied a large cohort of children undergoing myringotomy and ventilating-tube placement for chronic or recurrent otitis media under general mask anesthesia with halothane. The group that had URIs had no difference in the incidence of respiratory problems, no increase in the severity of respiratory illness, and no increase in the duration of URI symptoms. When compared with matched unanesthetized controls, URI symptoms actually decreased in the group receiving halothane anesthesia. These beneficial results may have been influenced by the effects of myringotomy on the course of the infection, but there is also some laboratory evidence that halothane has viricidal properties in tissue-culture preparations. It is not known if the newer volatile anesthetics have similar effects.

Coté et al., in their investigation of the utility of capnometry and pulse oximetry in detecting adverse events during anesthesia and in a subsequent paper further analyzing these data, found that children with URIs commonly had mild oxygen desaturation both during surgery and in recovery (Coté et al., 1991; Rolf and Coté, 1992). Others have noted that postoperative oxygen requirements in these children are commonly transiently increased (Levy et al., 1992). It is possible that the cause is related to subsegmental atelectasis from increased quantity and viscidity of secretions, and that with deep breathing and coughing after emergence, reexpansion of these segments occurs. In the prospective study previously cited, patients with current or recent URIs had a greater incidence of respiratory complications, including breath-holding and desaturation less than 90%, although none of the complications was associated with long-term sequelae. Both the authors and an accompanying editorial concluded that most children with URIs who were not overtly ill and had no other complicating medical issues could, with judicious attention to anesthetic technique, be safely anesthetized with increased risk for only mild transient sequelae (Coté, 2001; Tait et al., 2001).

Although most children with clinically mild URIs can undergo anesthesia safely, the potential for more serious complications in children with URIs should not be overlooked. A prospective study of over 15,000 children found that children who developed laryngospasm were twice as likely to have a URI (Schreiner et al., 1996). The investigators found that the incidence of laryngospasm was most clearly related to the parent’s subjective assessment of a URI, and that younger age and surgeries involving the airway were additive risk factors. A prospective case-controlled study of 1283 children with URI who underwent general anesthesia found a two- to sevenfold increase in respiratory complications during the perioperative course when compared with their counterparts without URIs (Cohen and Cameron, 1991). The incidence was 11-fold higher if the patient was intubated. A very small minority of children with URIs who do not appear to be ill during the preoperative examination may develop acute respiratory failure after the induction of anesthesia or some time during the anesthetic course. Severe hypoxia, bronchospasm, ventilatory insufficiency, and reduced compliance may occur and may even require postoperative ventilation and critical-care management. Some of these children have an unrecognized underlying lower tract disease, such as pneumonia, and others may experience shunt and ventilation-perfusion mismatching from atelectasis and pulmonary collapse as a result of inspissation of secretions and mucus plugging (Campbell, 1990; Williams et al., 1992). In rare instances, cardiomyopathy may follow viral illness. There are several reports of cardiac dysrhythmias or collapse occurring after induction of general anesthesia that were attributed to postviral myocarditis. The onset of abnormal rhythms on the ECG tracing or sudden deterioration of blood pressure or perfusion should alert the anesthesiologist to this possibility (Brampton and Jago, 1990; Terasaki et al., 1990).

It should be kept in mind that all of the ill patients who are included in these studies had mild to moderate URIs—children who were more severely ill had their surgery cancelled by the clinicians responsible for their care and were never enrolled in the study. Thus, clinical judgment remains crucial in deciding whether or not to cancel a case. Firm criteria for when to proceed and when to cancel are hard to discern, but the most current data suggest that there are several guidelines that can be applied:

• Laboratory tests are usually not useful; clinical impression is more reliable, such as noting the presence of toxicity, fever, purulent nasal discharge, productive cough, or wheezing. If physical examination suggests pneumonia, a chest radiograph may be confirmatory.

• There should be a lower threshold for postponing surgery in patients at increased risk, such as former premature infants, children with underlying pulmonary disease (e.g., asthma or bronchopulmonary dysplasia), infants younger than 1 year of age, and children with sickle cell disease.

• Patients who are to undergo surgery involving the airway should be considered at increased risk.

• If endotracheal intubation can be avoided, it is likely to decrease the risk of complications. Data suggest that the risk of airway complications in children with URIs is least with a conventional face mask, intermediate with a laryngeal mask airway (LMA), and greatest with an endotracheal tube (Tait et al., 1998, 2001). A logistic regression based on retrospective data did not identify any specific clinical factors that were associated with a higher incidence of adverse respiratory events during anesthesia in children with URIs, it but did find an association with endotracheal intubation and to a lesser degree with the use of an LMA, as compared with mask anesthesia (Rachel Homer et al., 2007).

• If a child is deemed too ill for anesthesia and surgery to proceed, it is best to wait 3 to 4 weeks from the resolution of the URI to reschedule the operation to allow for resolution of airway hyperresponsiveness. The aforementioned logistic regression found an increased incidence of adverse airway events if the peak symptoms of the URI had occurred within 4 weeks of the anesthetic (Rachel Homer et al., 2007).

• One should anticipate that the child with a URI might have a modest prolongation in PACU stay because of transient oxygen requirements or other mild respiratory symptoms that can delay discharge.

Asthma

The prevalence and severity of asthma, especially in children, remains a significant health problem in the United States. As of 1998, 6.4% of the U.S. population carried the diagnosis; two thirds of those were children. A more recent assessment of prevalence rates from 1980 to 2007 found that the prevalence plateaued in 1997, but that 9.1% (or 6.7 million) of American children carried the diagnosis (Akinbami et al., 2009). Nearly one-half million patients are hospitalized yearly with exacerbations of asthma, and almost half of those are children. The prevalence has increased by about 60% in the past 20 years before leveling off in the past 10 years. The death rate, although small, more than doubled from 1975 to 1995, but it appears to have stabilized in the past decade. Children with asthma can be safely and effectively anesthetized for same-day surgery, but careful preoperative preparation and evaluation, as well as intraoperative management, are crucial to avoid exacerbations and complications. Although it was previously common to think of asthma in terms of bronchospasm, current definitions of the disease emphasize the role or airway inflammation in pathogenesis, progression, and management. Recent consensus conferences of the National Institutes of Health (NIH) National Heart, Lung, and Blood Institute have defined asthma as a chronic inflammatory disorder of the airways that comprises many cells beyond those structural elements of the airways themselves, including mast cells, eosinophils, and T lymphocytes. The inflammatory processes that are involved in both the pathogenesis of the disorder, as well as in the progression of disease, are now addressed much more effectively in therapy for all patients with asthma and not only those with severe disease. The mainstay of therapy in the past was the chronic use of bronchodilator therapy, with antiinflammatory drugs reserved for the more severe cases; current thinking is that the first line of treatment should target inflammation with drugs such as inhaled steroids and newer drugs targeting inflammatory mediators (see Chapter 36, Systemic Disorders).

Anesthetizing the child with asthma for outpatient surgery involves the same general principles as for inpatient procedures (Pradal et al., 1995). It is critical for the asthmatic patient to closely adhere to their medication regimen before surgery. Inhaled steroids and agents like leukotriene inhibitors and cromolyn all require regular use for efficacy. The patient must use these medicines regularly and faithfully in the days (and weeks) before undergoing anesthesia. For those who have required systemic steroids in the past, a short course of steroids, beginning 24 hours before induction of anesthesia, may be advisable, particularly if intubation of the trachea will be required. Preoperative treatment with a short acting β-agonist such as albuterol may be helpful as well, even if the patient is not symptomatic, because events may occur during surgery that are likely to provoke airway irritability, especially intubation (Maslow et al., 2000). Much like the child with a URI, avoidance of intubation and airway stimulation, if possible, reduces the potential for exacerbation of airway irritability.

Volatile anesthetics, which have bronchodilatory properties, have obvious advantages in the child with asthma. Propofol, which has been shown to relax tracheal smooth muscle in vitro and to decrease airway resistance in subjects with and without asthma during induction of anesthesia, is an excellent choice when an IV induction is used (Pizov et al., 1995; Eames et al., 1996). This effect on airway smooth muscle has been shown to be even greater than that of ketamine and was also demonstrated during maintenance when an infusion was continued during the anesthetic (Pedersen et al., 1993). A propofol-based anesthetic, combined with either regional anesthesia or a non–histamine-releasing opioid, is a good alternative to volatile anesthesia when a total IV technique is indicated or desired. Some caution must be taken with the sulfite-containing preparation of propofol, as one study in adults has demonstrated a significant increase in airway resistance with this formulation compared with the non–sulfite-containing drug, although adverse clinical events have not been often reported despite widespread use (Rieschke et al., 2003).

Emergence from anesthesia is perhaps the most vulnerable period that is faced during the case. Although the stimulation of intubation at induction is unquestionably a time of increased risk, the ability to treat bronchospasm by deepening the anesthetic in response to airway hyperreactivity is not present at emergence. There is, therefore, a significant advantage to deep extubation when a volatile technique is used, because the patient can awaken without the endotracheal tube (a highly potent stimulus to the airway) in place. Judicious timing of extubation during emergence from total IV anesthesia can accomplish the same goal.

The risk from anesthesia in a child with an active exacerbation of asthma is certainly increased, and careful attention must be given to postponing procedures in these patients until baseline control of the disease is regained. The child with severe asthma who is never fully “clear” can still be a suitable candidate for outpatient surgery if the clinical management is optimized; there is aggressive preoperative treatment, such as a short course of systemic steroids, increased bronchodilator therapy, and strict avoidance of airway irritants like tobacco smoke is instituted; and contingency plans for admission are made in the event of an exacerbation.

Diabetes

Type I diabetes in children is relatively common, occurring in approximately 1 in 500 school-aged children, but data on the optimal intraoperative management of children with this disease are scant. Although there are no prospective investigations published in the English language literature on the subject, there are two recent reviews and consensus guidelines on the perioperative management of insulin-dependent diabetes in children that offer excellent and well-reasoned guidance on their care (Rhodes et al., 2005; Betts et al., 2007). Although many of the problems in anesthetizing adults relate to the late complications of this condition (e.g., damage to many end-organ systems and autonomic dysfunction), these problems are less prevalent in children, and the most common issue is that of glucose control. Children with diabetes can be safely anesthetized as outpatients if great care is taken to maintain good glucose homeostasis. The child should observe the usual fasting guidelines for elective surgery and should be scheduled for surgery early in the day. If the child is receiving a split-dose insulin regimen with short- and intermediate-acting insulins, the child may receive half of the usual intermediate- or long-acting insulin dose on the morning of surgery and omit any short-acting insulin (McAnulty et al., 2000; McAnulty and Hall, 2003). For children receiving a basal insulin regimen, there should be no short-acting insulin administered at all on the morning of surgery, but they should be given the usual dose of insulin glargine, an insulin for basal control with no true peak and a very long duration of action of about 24 hours (Chase et al., 2008; Hirsch, 2005). In all cases, the blood glucose level should be checked upon awakening and again 2 to 3 hours later. Intravenous infusions containing 5% glucose have often been recommended for intraoperative fluid management, but it has generally been found easier to use a non–glucose-containing IV fluid into which a glucose-containing IV is “piggybacked.” In this manner, the patient’s fluid requirements and glucose requirements can be independently regulated. Because the most potentially catastrophic complication of diabetes during surgery is unrecognized hypoglycemia, and symptoms of hypoglycemia may be undetectable during anesthesia, blood glucose levels should be checked every 30 to 60 minutes during the procedure. Hypoglycemia should be treated promptly by reducing or stopping any insulin administration and increasing the IV glucose rate, and hyperglycemia (blood glucose levels over 250 mg/dL) should be treated with a continuous insulin infusion titrated to effect, usually beginning at a rate of 0.05 units/kg per hour. The very short duration of action of IV regular insulin (about 5 minutes) makes glucose control much easier with this method (Barnett et al., 1980). The same management scheme is continued in the PACU until the patient is awake and taking oral fluids without difficulty. At that time, a dose of subcutaneous regular insulin can be administered and an oral diet begun. The patient should check blood glucose levels often during the postoperative day, because the stress of surgery often alters insulin requirements. The dose should be adjusted accordingly. The usual insulin regimen can often be restarted on the day after surgery.