Evaluation and Preparation of the Pediatric Patient for Surgery

Surgery is one of the most stressful and frightening times in the lives of both children and parents.¹

The pediatric anesthesiologist plays a pivotal role in 178providing the patient and family with appropriate information in a compassionate way, and in deciding which interventions will best prepare both the child and the parent for surgery. In this article we will describe the steps in preoperative evaluation and overall preparation of pediatric surgery patients.

A thorough preoperative evaluation and preparation of the child is essential and starts with obtaining the medical history of the child including the birth and neonatal history, experience with previous anesthetics and a family history of medical problems. Specific queries should focus on anesthetic-related disorders such as postoperative emesis, malignant hyperthermia, opioid-related hypersensitivity, or pseudocholinesterase deficiency.² The time of the last meal and liquid intake must also be obtained.³

The standard physical examination should involve all systems: cardiac, pulmonary, abdominal, head, eyes, ears, nose, throat, skin, and neurologic examination. Pediatric anesthesiologists will place particular emphasis on the airway and pulmonary system examination. The examination of the airway with determination of the Mallampati class will help the anesthesiologist to anticipate a potentially difficult airway and have a plan for its management including the availability of appropriate equipment.² In children with a history of prior asthma or a recent upper respiratory infection (URI), careful auscultation of the lungs will help the anesthesiologist to decide whether or not to postpone the procedure. Most children undergoing surgery are healthy, but in tertiary care centers, it is not unusual to care for chronically ill children with various implanted medical devices such as gastrostomy and tracheostomy tubes, cardiac pacemakers, defibrillators, neurological stimulators, ventriculoperitoneal shunts, dialysis, or vascular access catheters.⁵ Proper functioning of these devices must be confirmed and special precautions taken during surgery including disabling the device if necessary.179

Preoperative laboratory studies such as complete blood counts, clotting functions, routine urine, electrocardiograms, and chest X-rays are usually unnecessary for the otherwise healthy child. If the surgery has the potential for blood loss requiring transfusions, a baseline hemoglobin and hematocrit may be warranted along with the appropriate type and cross matching of blood products in keeping with the maximum surgical blood ordering schedule for that procedure. Some institutions routinely perform a pregnancy test in adolescent postmenarche females. The pediatric anesthesiologist has to exert special effort to uphold patient confidentiality and observe the local medicolegal regulations.⁶

A large prospective cohort study of over 17,000 children showed that 6.6% had at least one intraoperative respiratory event and children with a URI were 8.9 times more likely to have such an event [odds ratio (OR) 8.94; 95% confidence interval (CI) 6.14–13.22].⁷ Endotracheal intubation in a child with URI symptoms further increased the risk of events to 11 times than in children without URI.⁷ Other cohort studies suggest a two- to threefold increase in transient desaturation in the perioperative period, but differences in definition of URI and desaturation makes it difficult to compare studies.⁸ A single study that distinguished minor desaturations (<95%) from major desaturations (<85%) found no association between URI and the more significant events.⁹ No relationship between URI symptoms and laryngospasm and bronchospasm was found in a prospective cohort study of over 1,000 children. However, the likelihood of breath holding and cough were increased.¹⁰

The ex-premature infant has an increased risk of postoperative apnea as shown in both retrospective and prospective studies. Coté pooled individual patient data from 255 former premature infants in eight prospective studies and calculated the probability of postoperative apnea occurring using a logistic regression model. The likelihood of apnea was inversely related to both gestational age and postconceptional age. In preterm infants who were not anemic and had no apnea in the recovery room, the risk of apnea was less than 5% at 48 weeks postconceptual age (PCA) with a gestational age of 35 weeks or at 50 weeks PCA and 32 weeks gestation. However, the risk of apnea was less than 1% only when the PCA was 54 weeks with a 35 week gestational age or at PCA of 56 weeks and gestational age of 32 weeks. A hematocrit less than 30% was significantly correlated with the likelihood of apnea, particularly in those children greater than 43 weeks after conception.¹³ Assuming no apnea was witnessed in the PACU and the hematocrit was greater than 30%, the risk of apnea in a 60-week postconception infant undergoing herniorrhaphy would be less than 0.05%. There are data to suggest that intravenous (IV) caffeine reduces this risk. However, these are old studies from 1995 when current drugs such as sevoflurane, propofol, and regional anesthesia were not used as often as today. The recommendation of keeping such children in hospital for 24 hours for respiratory monitoring is well-established and recently re-examined using data from the general anesthesia versus spinal regional anesthesia (GAS study).¹⁴

Obstructive sleep apnea can result in serious cardiac, pulmonary, and central nervous system impairment and may resolve with tonsillectomy.¹⁶ However, a small subpopulation is at high risk for postoperative upper airway obstruction and the risks factors include age less than 2 years, craniofacial anomalies, obesity, failure to thrive, neuromuscular disorders, cerebral palsy, respiratory distress index more than 40, and lowest oxygen saturation less than 70%. These children are more susceptible to respiratory depressant effects of opioids and may need only 10% of the usual dose. Such patients should be admitted for overnight observation. They may need bilevel positive airway pressure, nasal airway, and supplemental oxygen in the PACU and in rare cases are left intubated till the airway swelling reduces. Preoperative history and physical examination may identify such subjects.^15,16

The principles for the evaluation and preparation of premature infants remain the same as in older children. However, there will be a greater focus on cardiorespiratory and central nervous system with careful consideration for possible congenital heart disease. These children are often unstable and the major problems of transporting them to the operating room without an untoward event are clinically significant.¹⁷ There is a need to understand that drug pharmacokinetics differs in neonates because of increased total body water compared to older children, and drug doses will require to be adjusted for immaturity of enzyme systems. It is beyond the scope of this article to discuss this in depth and readers are referred to textbooks and review articles.²

Studies have well-established that the emptying time of the stomach for clear liquids is short and the residual gastric contents after a period of withholding clear liquids for 2 hours is the same as longer periods of withholding fluids. Breast milk, however, requires to be withheld for a minimum of 3–4 hours. Solid foods should be withheld for longer periods of time. This has improved parental satisfaction without altering the incidence of pulmonary aspiration.³

Kain et al. estimated that 50–75% of children in the United States will experience fear and anxiety before procedures.^18,19182

They noted that approximately 50% of all children had negative behavioral changes such as new onset anxiety, night time crying, enuresis, separation anxiety, temper tantrums, and sleep or eating disorders up to 2 weeks or longer after surgery.¹⁹ However, findings of these studies suggest that we should examine if changes in our practice can reduce or prevent such negative behavioral changes with appropriate preparation of the child prior to surgery.

There are many nondrug interventions that have been employed to reduce patient and parent anxiety prior to surgery. One of the most common interventions is the use of parental presence during induction (PPI). Studies have shown that the older children with a mild temperament along with a parent of low trait anxiety have the best reduction in anxiety when PPI occurs.^20,21,26 In a randomized trial, PPI has not been shown to be helpful in reducing the child's anxiety scores at introduction of the mask, compared to oral midazolam, although it did result in better parental satisfaction.^25,29,30 The claimed advantages of PPI of anesthesia include minimizing the need for premedication and avoiding a dramatic separation. The disadvantages associated with PPI include disruption of the OR routine, compromising sterility, a possible adverse reaction of a parent, stress for anesthesiologist, with a potential for complications, and medical legal implications.

Other more traditional interventions focus on educating the child and the parent. This is not a new concept and started in the 1970s with modeling programs using books, video games, and puppet shows. In the 1990s, family centered care was initiated. In 2007, Kain et al. performed a randomized trial that determined family centered preparation improved overall perioperative outcomes in 408 children randomly assigned to one of four groups.²² The primary outcome measured was preoperative anxiety levels using the mYPAS and the secondary outcome measured was parental anxiety measured using the State Trait Anxiety inventory (self-report anxiety instrument). This study showed parents and children in the ADVANCE group (Anxiety Reduction, Distraction, Video education, Adding parents to the experience, No excessive reassurance, Coaching parents and Exposure to mask for practice) had lower anxiety levels in the holding areas than all other groups.²² When considering the implementation of such a program, one must consider the cost and time commitment of personnel.

Some studies have advocated teaching medical staff and parents' behavior that would minimize the pediatric patient's anxiety. Interventions that increased anxiety included excessive reassurance, bargaining, allowing the child to dictate the timing of induction.³¹ The staff should be educated to inform the child what will happen in specific terms of what would be done (e.g., placing mask on the face), where and how long it will last, and how it would feel including any pressure or discomfort (e.g., smell of the inhaled agent).²²184

A number of creative methods of distracting the child have worked well in reducing anxiety and improving the perioperative experience of both the child and the parent. These include magic tricks, toys, stories, video games, cartoons viewed on TV screens, phones, iPad apps, etc.³² They noted that video games were more effective at reducing anxiety upon entry to the operating arena compared to no intervention. However, midazolam provided the greatest reduction in anxiety compared to the handheld video game. In another study, music therapy was ineffective.³³

The most commonly used medication to decrease the anxiety felt by the pediatric patient prior to surgery is the water-soluble benzodiazepine midazolam, which can be given by the IV, intramuscular (IM), intranasal (IN), oral (per os), or rectal routes (Table 2).³⁴ Unfortunately, intranasal midazolam causes discomfort from a burning sensation when sprayed on the nasal mucosa. Midazolam premedication decreases the incidence of negative postoperative behaviors such as night time crying and awakening in children.^19,23,34 In clinical practice, it is essential to choose the timing of separation when blood levels are at the highest for best effects, but there remains a small group of patients who do not respond to oral midazolam premedication. Studies have shown this is not due to lower blood levels but may be related to the inherent temperament of the child. Combinations of midazolam with other drugs may be required for these patients but the potential for respiratory depression increases when opioid and midazolam combinations are used.

Another premedication often used for preoperative anxiety is ketamine, a phencyclidine derivative with antagonist activity toward the N-methyl-D-aspartate receptor.³⁵ This drug also has analgesic, amnestic, and anesthetic effects.³⁶ Ketamine can be given intramuscularly, intravenously, or orally.^35,37 The bioavailability of IM ketamine is approximately 93% compared to 17% for the oral route, making the quicker onset with the IM route useful in the clinical scenario of an out of control child. The preservative in ketamine has potential neurotoxic effects, and so the nasal route is not recommended unless preservative-free ketamine is used. Due to several potential negative effects of ketamine, its use is typically relegated to the combative, developmentally delayed child who has not responded to midazolam and needs to be transported to the operating room for a safe induction of anesthesia. The disadvantages associated with ketamine include increased oropharyngeal secretions, psychomimetric side effects (hallucinations, nightmares), and postoperative nausea and vomiting.^35,37 The typical dose of ketamine used for preoperative sedation is as low as 2 mg/kg and as high as 7 mg/kg IM to allow for adequate sedation within 3–5 minutes. When given orally, the dose of 5–6 mg/kg will sedate most children in approximately 10 minutes.^35,37

The alpha 2 agonist, clonidine has been shown to be effective in sedating patients, reducing anxiety, salivation, gastric acid production, sympathetic effects, postoperative nausea, and vomiting.³⁸ The benefits of clonidine are outweighed by the very long time to peak effect, with peak plasma concentration occurring 60–90 minutes after oral administration.³⁹ This would require drug administration at least 1 hour in advance, which can challenge the efficiency of operating rooms with rapid turnover rates.

Dexmedetomidine is a more selective alpha 2 agonist with a shorter elimination half-life than clonidine. It has both sedative and analgesic properties that have been shown to be beneficial in the prevention of preoperative anxiety and reducing the incidence of ED.^40,41 Dexmedetomidine has the advantage of being an odorless and tasteless drug that produces reasonable sedation, with minimal respiratory depressant effects.⁴² Bradycardia, hypotension, and hypertension occur to varying degrees depending on the age of the child. It has been used widely for sedation, analgesia, and in children with neurological diseases, such as mitochondrial disorders.^41,43–45 The main disadvantage of dexmedetomidine for premedication is the 45–60 minutes time needed to achieve a clinical effect 186after oral intake. Such a prolonged amount of time can be quite problematic and impossible to employ in a busy day surgery setting. The drug has a long half-life and can delay emergence.⁴⁵

The use of anticholinergics such as atropine and glycopyrrolate in premedication has decreased over time. They were initially routinely used in the ether era when excessive secretions were a major problem. With the advent of halothane the secretion problem was decreased, but bradycardia and arrhythmias were not uncommon, leading many pediatric anesthesiologists to continue their routine use.⁵⁰ Anticholinergic premedication was administered primarily in otorhinolaryngology, oral surgery, ophthalmology, and bronchoscopy procedures to inhibit excessive secretions, prevent vagal reflexes, and avoid laryngospasm.⁵¹ However, cardiovascular depression and perioperative arrhythmias decreased with the widespread use of sevoflurane. One study compared the metabolic and clinical responses of 76 children receiving atropine plus meperidine, glycopyrrolate plus meperidine, or diazepam premedication to placebo. The increased oxygen consumption and energy expenditure with anticholinergics were not considered clinically significant in children older than 4 years of age. However, the increased heart rate was deemed inappropriate for routine clinical purposes.⁵¹ A survey of Finnish anesthesiologists indicated that the use of anticholinergic premedication 187decreased from 50 to 33% over an 8-year period.⁵² Malik and colleagues studied 1,000 patients to determine the effectiveness of anticholinergics in reducing airway secretions for flexible bronchoscopy and noted that such premedication might reduce airway secretions.⁵³ However, there continued to be more hemodynamic variation with anticholinergic premedication compared to placebo. In the last few years, dexmedetomidine has started to be used more extensively, particularly in children undergoing adenotonsillectomy. Studies have shown that administration of anticholinergic drugs to children receiving dexmedetomidine has been associated with hypertension.^40,42,45 The routine use of anticholinergics for all children is no longer recommended, but these drugs may have a role to play in cases where surgical stimulation is likely to result in vagal responses, e.g., strabismus surgery.

Adequate preparation of the pediatric patient for surgery allows the anesthesiologist to have a medically optimized and psychologically ready patient. The thorough history and physical exam and use of pharmacological and or nonpharmacological interventions to combat preoperative anxiety will lead to a smooth induction and may result in smooth emergence and PACU stay. Preoperative anxiety is a phenomenon that affects most of our patients. As perioperative specialists, we must understand the various components of preoperative anxiety. We are challenged and obligated to provide both the child and the parent a stress free, pleasant perioperative experience. We should use all of our pharmacological and nonpharmacological resources for distracting the child. Many children's hospitals in the United States have Child Life Specialists present to minimize preoperative anxiety and reduce negative postoperative behaviors. However, these programs as stated before are expensive. Despite the production pressures in busy operating theater suites, the anesthesiologist must be flexible, compassionate, and willing to adjust his or her approach to improve the child and the family's experience during this stressful period.