Transport to the Care Unit

Transport from the operating room to the PACU should be carried out under the direct supervision of a trained expert. The security and patency of the airway, intravenous and arterial lines, drains, and urinary catheters should be checked before transport. The security and patency of the tracheal tube (if the airway remains intubated) or laryngeal mask airway, all intravenous lines, the arterial line, chest tubes, drains, and the urinary catheter should be checked before transport. Children should be in presentable condition (e.g., removal of blood and secretions) before and kept normothermic during transport to the PACU or PICU.

Unless children are awake, with protective airway reflexes intact, or unless there is a specific contraindication, it is sensible to transport extubated children in the lateral position (i.e., tonsillectomy recovery position) so that the tongue lies away from the larynx, and secretions and vomitus leave the mouth rather than enter the larynx, causing aspiration or airway obstruction. To assess ventilation and maintain a patent airway with the child in the decubitus position, we recommend applying the thumb to the forehead to extend the neck and holding the fingers (the finger tips are the most sensitive part of the hand) over the mouth (or nose) to feel for exhalation. A precordial stethoscope may also be used to auscultate respirations. If the child is breathing room air, a pulse oximeter can indicate oxygenation and serve as a crude measure of ventilation because desaturation will occur quickly if hypopnea develops. However, if oxygen is provided to the child, the oximeter can no longer serve as a guide to ventilation, because desaturation will not occur until a sustained apnea occurs. For sleepy children, the precordial stethoscope and portable oxygen saturation monitor can trend ventilation, oxygenation, and the heart rate within the previously described provisos. We recommend that children in a potentially unstable condition be transported with a pulse oximeter, capnogram, an electrocardiographic (ECG) monitor, and a blood pressure cuff or a transduced arterial line. The monitoring lines, intravenous drips, infusion pumps, and other equipment should be clearly labeled and simplified before transport. For sick children, those with intubated tracheas, and children with potentially difficult airways, an appropriate resuscitation bag, facemask, oral airway, oxygen tanks (oxygen levels should be checked), functioning laryngoscopes, tracheal tube, and medications (including atropine and succinylcholine) should be carried en route to the PACU or PICU. A tackle box containing all of this equipment is helpful, especially when children are transported to the PICU in an elevator. Children receiving vasoactive drugs require infusion pumps so that these agents can be continuously administered at precise titrated rates.

Transport to the PACU or PICU is a time of potential danger. Distance and duration of travel should be minimized. When designing pediatric perioperative areas or reallocating space, strong emphasis should be placed on ergonomics.

A child often appears awake after the stimulation of tracheal extubation and transfer to the stretcher but may subsequently become obtunded and obstruct the airway during transit to the PACU or PICU. Just as frequently, children may become restless during transit. Although restless behavior has many causes, hypoxia should never be overlooked. The guard rails on the stretcher should always be raised when the child is in it. Most importantly, the anesthesiologist must remain vigilant throughout the transfer.

Arrival in the Care Unit

On arrival in the PACU, attention should first be directed to the airway, ensuring it is patent and not obstructed; to the color of the lips and mucous membranes; to the oxygen saturation; and to the adequacy of ventilation, perfusion, and central nervous system function. Admission heart rate, blood pressure, oxygen saturation, respiratory rate, and temperature should be recorded on arrival. The nurse-to-patient ratio should be 1 to 1 for sick children and 1 to 2 or 1 to 3 for routine cases. Supplemental oxygen is administered as indicated, recognizing the limitations of the monitors to detect ventilation in such cases. Many children object to having an oxygen mask fixed to their faces; a funnel-type mask or open hose with large flow rates may be less objectionable (although less optimal). Thereafter, report should be given to the nurses and physicians in attendance. Ideally, the nurses taking care of the child postoperatively are already familiar with the child and family from the preoperative setting.

The standardized transfer of care report should include, at a minimum, the child’s name, institutional identification code, age and gender, preoperative vital signs, and specific circumstances, such as a language barrier or developmental delay. The size and location of catheters, a description of the child’s current problem, medical history, medications, allergies, operative procedure, and pertinent surgical problems should be outlined. The anesthetic should be summarized and include the premedication and anesthetic agents used at induction and for maintenance, techniques used, reversal of neuromuscular blockade (i.e., adequacy of the train-of-four response), estimated blood loss, fluid replacement (including amount and type of solution), urine output, and vasoactive drugs, bronchodilators, and intraoperative medications (e.g., antibiotics) used. Regional anesthesia issues, such as epidural use and location, drug choice and concentration, use of adjuvants, effective level of analgesia, and drug infusion rate should be clearly communicated. Administration of analgesics (time and dose), local blocks and wound infiltration with local anesthetics, problems with surgery or anesthesia (e.g., difficult intravenous access, difficult intubation, intraoperative hemodynamic instability, cardiac changes), and potential problems in the PACU should be listed.

The anesthesia team must remain with the child until he or she has stable vital signs and the PACU team is comfortable and ready to assume responsibility for the child. Physicians who will be in charge of taking care of the child in the PACU after the anesthesia team leaves must be clearly identified by name, and ways to reach them (e.g., pager number) must be given to surgeons, anesthesiologists, and regional block and pain services.

All children should be monitored continuously in the PACU. At the very least, this should include continuous pulse oximetry and intermittent noninvasive blood pressure and temperature monitoring. Most PACUs also monitor the electrocardiogram continuously, although some limit this to children with cardiac disease or complex multiple-organ disease. During emergence, many children are so active that it is impossible to maintain the monitoring devices in place. If the child is not hypoxic and is sufficiently awake to remove the monitors, he or she probably does not require the monitors any longer. If the child falls back to sleep, then a pulse oximeter probe should be reapplied, particularly for at-risk children such as those with obstructive sleep apnea. For a child who is physically or mentally challenged, it may be necessary to apply light restraints until he or she is oriented and awake.

Pharmacodynamics of Emergence

Emergence from anesthesia is faster after a relatively insoluble inhalational anesthetic agent such as sevoflurane or desflurane than it is after a more soluble agent such as halothane.³ However, the clinical importance of these differences may be minimal and vary with the duration of anesthesia and the coadministered medications. Differences in the times to discharge from the PACU and the hospital between inhalational agents are even more difficult to detect when specific comparisons are made because so many other factors, such as pain management, agitation, availability of hospital beds, and family circumstances, affect discharge readiness.

The age of the child exerts a minimal influence on the wash-out of inhalational anesthetic agents and has little impact on the rapidity of emergence, although age may be a factor for infants younger than 1 year of age.⁴ However, the overall clinical implications of age-related differences in emergence are exceedingly difficult to detect.⁵ The speed of emergence correlates more closely with the duration of anesthesia. The greater the duration of anesthesia, the more the tissue compartments become filled with these anesthetics and the more time it takes to eliminate these anesthetics and for the child to recover. For example, emergence from 30 minutes of sevoflurane anesthesia is significantly faster than emergence from 2 hours of anesthesia, which is more rapid than from 8 hours of anesthesia.⁶ This relationship between emergence time and the duration of anesthesia has less relevance as inhalational anesthetics have become less soluble (e.g., desflurane).

Emergence from intravenous agents can vary significantly from that of inhalational agents. Several studies have evaluated the quality and rapidity of emergence after intravenous anesthetic agents compared with that after inhalational agents. For outpatient surgery, emergence after propofol anesthesia is as rapid as that after sevoflurane but with far less agitation and pain behaviors.^7,8 The recovery characteristics of propofol with remifentanil total intravenous anesthesia have been compared with those after desflurane inhalational anesthesia. Recovery is as rapid as that after desflurane with nitrous oxide, with a similar incidence of nausea and vomiting but with much less agitation.⁹

Midazolam is rarely used for maintenance of anesthesia but is often used as an oral or intravenous premedication for anxiolysis and amnesia in the preinduction period. There is evidence that the addition of midazolam in the preinduction period to an inhalational or propofol anesthetic may delay early emergence after brief anesthesia. However, this effect of midazolam is attenuated after anesthesia of greater duration, or when considering late emergence, this effect is minimal.¹⁰ Midazolam does not affect the incidence of postoperative agitation.^11,12

Emergence Agitation or Delirium

Emergence agitation (i.e., emergence delirium [Videos 46-1 and 46-2]) was first described in a large cohort of postsurgical patients almost 40 years ago.¹³ From a clinical perspective, it is often impossible to differentiate pure agitation from delirium. Delirium implies a specific set of thought disorders and hallucinations based on the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). Despite numerous investigations, differentiating emergence delirium from postoperative pain has also proved difficult. Emergence delirium usually manifests as thrashing, disorientation, crying, and screaming. The child is unable to recognize parents, familiar objects, or surroundings; is inconsolable; and talks irrationally during early emergence from anesthesia. Emergence delirium occurs more often in children (rate of 10% to 20%) than in adults, particularly in those younger than 6 years of age.^14,15 It may in part reflect differences in clearance of insoluble inhalational agents from the central nervous system.

An emergence delirium scale has been developed and validated that may provide clinicians and investigators with a tool to differentiate emergence delirium from pain.¹⁶ Tables 46-4 and 46-5 show two scoring systems used to evaluate emergence behaviors in children. In evaluating emergence delirium with the Pediatric Anesthesia Emergence Delirium (PAED) scale after anesthesia, preliminary evidence suggested that values greater than 10 were consistent with emergence delirium in 37% of patients,¹⁷ although that cutoff value has not been useful for others.¹⁸ Later evidence suggested that values greater than 12 provided greater sensitivity and specificity.¹⁷ In the PICU, evidence suggests that a PAED score greater than 8 predicts emergence delirium.¹⁹

TABLE 46-5 Postanesthesia Behavior Assessment Scale

^*A higher postanesthesia behavior assessment (PABA) score is associated with a greater degree of postanesthetic distress.

From Przybylo HJ, Martini DR, Mazurek AJ, et al. Assessing behavior in children emerging form anaesthesia: can we apply psychiatric diagnostic techniques? Pediatr Anesth 2003;13:609-16.

Our understanding of emergence delirium or agitation continues to evolve, but it is clear that it occurs after surgical procedures and after procedures that are free from pain, such as magnetic resonance imaging.^14,20,21 Emergence delirium appears to occur more frequently after use of less-soluble inhalational anesthetics such as sevoflurane and desflurane than after more-soluble inhalational anesthetics such as halothane and isoflurane,^22,23 even though some data suggest otherwise.²⁴ There may be a greater incidence of emergence delirium after painful procedures; emphasizing the difficulty separating agitation due to pain from agitation due to the direct effects of the inhalational agents on the sensorium.²⁵ Emergence delirium occurs more commonly in children younger than 6 years of age than in older children, usually lasts 5 to 15 minutes, and resolves spontaneously if the children are left undisturbed or they are held by their parents.¹⁴

Several strategies have been used to decrease the duration and intensity of emergence delirium. Effective regional analgesia, opioids, ketamine, α₂-agonists, and propofol can prevent or treat emergence delirium. Low-dose fentanyl (2 µg/kg intranasally or 1 to 2 µg/kg intravenously) decreases the duration and intensity of emergence delirium,²⁶ even in the absence of significant painful stimuli.²⁰ Other adjunctive agents used to treat this phenomenon include ketorolac and acetaminophen (for myringotomy with ventilation tube placement) and midazolam; the effectiveness of midazolam, however, has been mixed.^27,28 Dexmedetomidine can decrease the incidence of emergence delirium,^29,30 but the cost-effectiveness of this treatment compared with others requires evaluation. Administration of propofol by continuous infusion or by bolus at the end of surgery appears to be preventative,^31,32 although these findings have not been consistent.¹⁸ The induction dose of propofol administered at the start of the case does not appear to prevent postoperative emergence delirium.³³ Regional analgesia in the form of caudal blocks can reduce the incidence of emergence delirium, although this effect is probably related to improved pain control, which eliminates pain as a source of agitation.^34,35

Although there is no evidence of long-term consequences, in the current era of fast-tracking anesthesia, emergence delirium can represent a significant time expenditure for nurses in the PACU. Discharge from the PACU may be delayed while waiting for the delirium to wane or for the effects of the interventional drugs to dissipate. Injury to the child who is extremely agitated is a concern. Parental satisfaction decreases when severe emergence delirium occurs. Although the impact of extreme delirium is not fully known, evidence suggests that the incidence of postoperative maladaptive behaviors increases among children who experience marked emergence delirium.³⁶

Criteria for Extubation

In most cases, extubation may be safely performed in the operating room. However, a child’s condition may necessitate delayed extubation at a more appropriate time in the PACU or PICU. There is widespread agreement that children who have been anesthetized with a full stomach, children at risk for airway obstruction, those with difficult airways, premature infants, and other infants predisposed to apnea should be awake before extubation of the trachea is attempted. Beyond this, the timing of extubation is a matter of individual judgment. For example, the practice at some institutions is to extubate the trachea when a child is awake and demonstrating eye opening and other purposeful movements; the practice at others is to extubate while the child is under a deep plane of inhalational anesthesia. Clinicians report only rare problems with either approach. Most clinicians agree that either approach is preferable to extubating the trachea during a very light plane of anesthesia, when laryngospasm is more likely and vomiting may occur while protective reflexes are impaired.

Extubation in the Operating Room or Postanesthesia Care Unit

Immediately after extubation, oxygen should be administered, and the child should be observed for adequate ventilation, satisfactory oxygen saturation, color of the mucous membranes, and laryngospasm or vomiting. Transport of children should not be undertaken until the patency of the airway and the adequacy of oxygenation and ventilation have been confirmed in the form of stable and satisfactory oxygen saturation and adequate respiratory effort. Our criterion for transporting the child from the operating room to the PACU without oxygen is a stable oxygen saturation of 95% or greater while breathing room air. If the child cannot sustain this level of oxygen saturation, more time for recovery in the operating room is taken, or the child is transported with supplemental oxygen and a means for providing positive-pressure ventilation.

For children who are extubated in the PACU, respiratory insufficiency is the most worrisome and most frequent complication. It comprises approximately two thirds of critical perioperative events when it is associated with emergence from anesthesia.³⁷ Respiratory insufficiency may manifest in the form of difficulty breathing, or it may be more subtle as anxiety, unresponsiveness, tachycardia, bradycardia, hypertension, arrhythmia, or seizures. Cardiac arrest is a late manifestation. When any of these conditions are present, respiratory insufficiency must be considered as the root cause. Hypoxemia, hypoventilation, and upper airway obstruction are the three most common adverse respiratory events that occur in children in the PACU, and this is particularly true for children after tonsillectomy complicated by obesity and possible obstructive sleep apnea and for those who have undergone diagnostic bronchoscopy.

Hypoxemia

Hypoxemia may result from hypoventilation, diffusion hypoxia, upper airway obstruction, bronchospasm, aspiration, pulmonary edema, pneumothorax, atelectasis, or rarely from postobstructive pulmonary edema or pulmonary embolism. Hypoxia occurs more rapidly and may be more profound during emergence from general anesthesia because general anesthesia inhibits the hypoxic and hypercapnic ventilatory drive, reduces functional residual capacity, and alters hypoxic pulmonary vasoconstriction. Shivering may further increase oxygen consumption by a factor of two to five^38,39 and exacerbate hemoglobin desaturation.

Postoperative hemoglobin desaturation is more common in children with or recovering from an active upper respiratory tract infection due to increased airway reactivity, atelectasis, and increased secretions than in children without a history of upper respiratory tract infection.^40,41 In neonates, hypoxia increases ventilation for approximately 1 minute but then depresses the respiratory drive (i.e., respiratory rate and tidal volume).⁴² The ventilatory response to hypoxia in formerly preterm infants with severe bronchopulmonary dysplasia who sustained an hypoxic injury is delayed for several months, placing them at particular risk for desaturation in the perioperative period.⁴³

Hypoventilation

Minute ventilation is the product of tidal volume and respiratory rate. It decreases when tidal volume, respiratory rate, or both values decrease. Hypoventilation leads to hypercarbia and promotes alveolar collapse, known as atelectasis. Severe hypoventilation causes respiratory acidosis, hypoxemia, carbon dioxide narcosis, and apnea. The ventilatory response to carbon dioxide depends on the child’s age. For example, during halothane anesthesia and spontaneous ventilation, 3.7% inspired carbon dioxide triggers no ventilatory response in infants younger than 6 months of age, but it triggers a 34% increase in minute ventilation in infants and children older than 6 months of age.^44,45

Hypoventilation results from a decrease in ventilatory drive, insufficiency of the muscular system, or mechanical effects. Inhalational anesthetics, opioids, benzodiazepines, and other sedating medications decrease the ventilatory drive in children in a dose-dependent manner. At particular risk for postoperative hypoventilation are children with underlying disturbances in respiration, such as infants with apnea of prematurity (formerly preterm infants of less than 60 weeks postconceptual age [PCA]); those with central nervous system injury such as head injury, strokes, and intracranial surgery; and obese children, especially those with obstructive sleep apnea (OSA). Some of these children require prolonged observation in a setting with continuous monitoring capabilities.

Muscular weakness may contribute to respiratory insufficiency. Preexistent muscular disease (e.g., muscular dystrophy) and inadequate reversal of neuromuscular blockade, electrolyte abnormalities, neurologic disorders, drugs, infection, and endocrine disease may impair the respiratory effort sufficiently to cause hypoventilation and respiratory insufficiency.

Respiratory insufficiency may result from upper airway obstruction. Airway obstruction is a feature in children with known airway problems due to congenital anomalies of the face (particularly those with midfacial hypoplasia as in trisomy 21, achondroplasia, and Crouzon disease) and obese children with a history of OSA. Inadequate analgesia can lead to splinting and hypoventilation, which may depress oxygen saturation.

Airway Obstruction

Among the most common and serious problems in the PACU is an extrathoracic airway obstruction. Clinical hallmarks of airway obstruction include hemoglobin desaturation with inspiratory stridor, inspiratory retraction, and paradoxical chest wall motion. Common interventions include stimulating the child, repositioning, suctioning, performing a jaw thrust, insertion of an oral or nasal airway, and application of positive end-expiratory pressure (PEEP) (see Fig. 12-10). If these measures fail, patency of the upper and lower airways should be considered because gas exchange may be compromised by laryngospasm, subglottic narrowing as the result of edema, bronchospasm, atelectasis, or tracheal secretions. Incomplete recovery from general anesthesia or neuromuscular blockade, wound hematoma, and vocal cord paralysis may also lead to upper airway obstruction.

If the airway is not cleared by any of the previously described maneuvers, placement of a tracheal tube preceded by administration of oxygen by mask with continuous positive airway pressure and indicated medications may be necessary. Postobstructive pulmonary edema is a complication of acute upper airway obstruction and the relief of chronic airway obstruction after tonsillectomy. The mechanism appears to be generation of extreme negative intrathoracic pressure against a closed glottis or obstructed airway and its sudden release, resulting in a dramatic increase in pulmonary blood flow and causing noncardiogenic or neurogenic pulmonary edema. This complication should be suspected when significant hypoxia, persistent tachypnea, or tachycardia follows a prolonged episode of laryngospasm, airway obstruction, or tonsillectomy and the child has pink, frothy secretions. Treatment of noncardiogenic pulmonary edema includes tracheal intubation, positive-pressure ventilation with PEEP, 100% oxygen to maintain an adequate oxygen tension, furosemide, and morphine. Furosemide (1 to 2 mg/kg) should be given immediately intravenously because it is thought to act instantaneously by decreasing venous return to the heart by direct venodilatation.^46–48

Postintubation croup or subglottic edema has been associated with factors such as traumatic intubation, tight-fitting tracheal tubes, multiple intubation attempts, coughing with an in situ tracheal tube, a change in the child’s position during surgery, prolonged duration of intubation, surgery of the head and neck, and a history of croup.⁴⁹ Treatment should be initiated with the inhalation of cool mist. If the symptoms do not abate, nebulized epinephrine should be administered, although its effects are temporary and its repeated use may be followed by rebound edema. The use of nebulized epinephrine indicates the need for a prolonged period of observation. Outpatients may have to be admitted to the hospital overnight or observed for an extended period.

Respiratory Effort

If the airway is patent, attention turns to the adequacy of ventilatory effort. Residual neuromuscular blockade can be diagnosed by observation (i.e., the patient’s ability to lift extremities against gravity or perform a sustained head lift) and quantitatively by assessment with a peripheral nerve stimulator. Depending on the severity and the clinical situation, this condition may be treated with supplemental doses of reversal agents or ventilatory assistance. If the respiratory rate is slow, suggesting opioid-induced respiratory depression, titrated incremental doses of naloxone (0.01 to 0.1 µg/kg) reverses the respiratory depression without precipitating acute anxiety, pain, or pulmonary edema. If naloxone is effective, continuous monitoring of respiratory status is advised because naloxone has a short half-life of 20 minutes. The same effective total dose should be given intramuscularly to prevent recrudescence of the opioid-induced respiratory depression. Residual sedation after benzodiazepines may be antagonized with flumazenil.

Children who have an adequate airway and adequate muscular strength may experience difficulty breathing because of pain, restriction from bandages or casts, abdominal distention, pneumothorax, atelectasis, aspiration pneumonitis, or cardiogenic or postobstructive pulmonary edema. In most cases, the history and physical examination focus the differential diagnosis, and when necessary, investigations that include a chest radiograph, blood gas analysis, and possibly invasive hemodynamic monitoring can identify the underlying cause and determine an effective treatment.

Discharge of Preterm Infants from the Postanesthesia Care Unit

Preterm infants (<37 weeks gestation at birth) are at risk for apnea after sedation and general anesthesia.^50,51 As the PCA (i.e., age since conception) increases, the risk for apnea decreases.⁵² Guidelines are lacking because there are inadequate randomized, controlled trials and underpowered institutional studies, and apnea has been reported even after more modern anesthetic agents (i.e., desflurane and sevoflurane). However, it is recommended that formerly preterm infants who are 55 to 60 weeks PCA who are not anemic and not experiencing apnea be observed for an extended period and, if stable, later discharged. Infants younger than 55 weeks PCA, those who are anemic (hematocrit <30%), and those with ongoing apnea should be admitted for monitoring.^53–59 Prophylactic administration of caffeine (10 mg/kg intravenously) may reduce the risk of apnea after general anesthesia for infants at high risk,^60,61 although it should not supplant postoperative admission and monitoring. Administration should be discussed with neonatologists, because it does not change management (i.e., infants are monitored in the hospital), and the administration of caffeine resets the number of apnea or bradycardia-free days (i.e., used as a discharge criterion for preterm infants) to zero. Preterm infants younger than 55 weeks PCA, particularly those with anemia or those with major cardiorespiratory or neurologic disorders, should be admitted and monitored for at least 12 apnea-free hours after general or regional anesthesia or sedation (see Chapter 4).^54,62

Although preterm infants who undergo surgery under spinal anesthesia have fewer respiratory and cardiovascular complications compared with those undergoing general anesthesia,^54,55,58,61 the infants remain at risk for apnea. It is unknown whether the risk is greater after a spinal anesthetic without supplemental sedation (with no other medication given) than the preoperative baseline risk. Similarly, caudal anesthesia has been reported as an effective alternative to spinal anesthesia in preterm infants undergoing herniotomy.^62,63 Infants who have received a spinal anesthetic supplemented with ketamine or midazolam are at greater risk for apnea than those who received no supplemental sedation. Despite evidence of a reduced risk of apnea after regional anesthesia^61,64 and no postdischarge complications on the day of surgery in some institutions,^61,65 there is insufficient evidence to make general recommendations regarding this practice. Our recommendation is to admit and monitor these infants.

Full-term neonates typically have a reduced risk of apnea and bradycardia after general anesthesia compared with preterm infants. Opinions vary on the minimum PCA for ambulatory surgery in infants 44 to 50 weeks PCA; many children’s hospitals admit all full-term neonates (<28 days of age) for overnight monitoring after general anesthesia, although this is not evidence-based practice. All full-term infants with a history of apnea and bradycardia or those who have siblings with sudden infant death syndrome should be observed for an extended period or admitted for overnight monitoring after general anesthesia.

Bradycardia

Bradycardia is the most common dysrhythmia in children and requires immediate attention because of its association with decreased cardiac output. Until proved otherwise, the most common cause of bradycardia in infants and children is hypoxemia. Other possible causes for the bradycardia include vagal responses (e.g., passage of a nasogastric tube), medications (e.g., neostigmine, β-adrenergic blockade, high spinal blockade, opioids such as fentanyl), increased intracranial pressure, and high neuraxial anesthetic block. The definition of bradycardia depends on the age of the child; the incidence decreases with increasing age (see Chapter 2).

Treatment is directed at correcting the underlying cause, including the administration of oxygen and ensuring a patent airway. Bradycardia should be immediately treated with oxygen and, if necessary, with ventilation. If intervention with oxygen does not immediately restore the heart rate, atropine (0.02 mg/kg) should be administered; and if no response is observed within 30 seconds, administration of epinephrine (2 to 10 µg/kg) is indicated. For symptomatic bradycardia (e.g., hypotension, decreased level of consciousness), immediate administration of epinephrine is indicated. If there is no response to epinephrine, chest compressions should be instituted and standard cardiopulmonary resuscitation algorithms followed (see Chapter 39).

Tachycardia

Tachycardia is an important postoperative sign that is a marker for one of several disorders, such as inadequate cardiac output or oxygen delivery, or it may be a response to pain or a direct drug effect (e.g., epinephrine, atropine). Tachycardia may occur in response to hypoxemia, hypercarbia, hypovolemia, hypervolemia, emergence delirium, anxiety, sepsis, fever, a full bladder, a previously unrecognized cardiac conduction abnormality (see Chapters 14 and 16), or heart failure. The threshold for diagnosing tachycardia varies with the age of the child, and the threshold decreases with age.

Treatment is directed at correcting the underlying cause. Occasionally, children present with a sustained tachycardia unrelated to the previously described conditions that is refractory to the usual therapy. A cardiac consultation is required to investigate and identify less common causes, such as an aberrant conduction system or ectopic foci as a source of supraventricular tachycardia (SVT). SVT, which is defined as more than 220 beats/min in infants and more than 180 beats/min in children, may be treated with adenosine when there are no other symptoms. However, SVT with accompanied hypotension or decreased level of consciousness may require cardioversion. Children who have had prior cardiac surgery are particularly at risk.

Other Arrhythmias

With the exception of bradycardia and tachycardia, postoperative arrhythmias are rare in children. Isolated premature ventricular or atrial beats may be observed in the PACU and, unless they progress, are not important. Multifocal premature ventricular beats are uncommon in children. They may occur as a result of inadequately treated pain, cardiac conduction defects, or in rare instances, may be a harbinger of malignant hyperthermia (see Chapters 14, 16, and 40), acute rhabdomyolysis with hyperkalemia, inadequately treated pain, a congenital conduction defect, or a structural cardiac defect. Electrolyte and arterial blood gas status should be checked. Children with known congenital heart disease should have continuous ECG monitoring in the PACU (see Chapters 14 and 16); all arrhythmias should be recorded and a cardiologist consulted because this may be the first manifestation of a developing ectopic focus.

Blood Pressure Control

Incidence of Postoperative Nausea and Vomiting

Postoperative nausea and vomiting (PONV) is one of the most bothersome adverse effects of anesthesia and surgery. Unlike adults, most children are unfamiliar with and have never experienced nausea. It is unlikely that they will warn the PACU personnel that they are nauseated. In children, vomiting and complaining about a “sore tummy” are likely the first and only manifestations of gastrointestinal upset. Among children, PONV is inversely related to age.⁶⁶ The incidence of PONV is small in very young children, increases throughout childhood, and reaches a zenith in adolescents, for whom the incidence exceeds that for adults.⁶⁶

The type of surgery influences the incidence of PONV. The incidence of PONV in children is greatest after tonsillectomy, strabismus repair, hernia repair, orchiopexy, microtia, and middle ear procedures.⁶⁷ Before puberty, there are no gender-related differences in PONV; after puberty, girls experience much more PONV than boys. The medical complications of PONV include pulmonary aspiration, dehydration, electrolyte imbalance, fatigue, wound disruption, and esophageal tears. PONV can produce psychological effects that may produce anxiety in the children and parents and lead them to avoid further surgery. The cost implications of PONV can be major because of delayed recovery and discharge, increased medical care, and reoperation. Although these problems are seldom life-threatening, the cumulative costs in terms of prolonged PACU stays, unplanned admissions, and patient dissatisfaction are serious.⁶⁸

Evidence-Based Consensus Management

Management of PONV is complex, and many treatment strategies have been formulated (Fig. 46-1). Most have been shown to be effective in one study or another. However, the superiority of some treatments over others has not been established, in part because of study design flaws such as inadequate dosing, small sample sizes, or various periods of observations and data collection; some studies monitored PONV only during the first few hours after surgery, whereas others monitored the children for 24 to 48 hours after surgery. To make sense of the conflicting data that exist, a consensus-based management strategy for the prevention and management of PONV has been devised.⁶⁹ These guidelines advise first identifying the children at significant risk for PONV as outlined earlier; prophylaxis for PONV is recommended for children in high-risk categories. Studies frequently focus on postoperative vomiting as the primary outcome because nausea may be difficult to identify in children.

FIGURE 46-1

Treatment strategies for postoperative nausea and vomiting (PONV).

The consensus guidelines recognize that the choice of anesthetic can influence the incidence of PONV in children. Propofol-based anesthesia during operations associated with a large incidence of PONV dramatically reduces the incidence of PONV compared with isoflurane-based anesthesia, even when both groups are given prophylactic 5-hydroxytryptamine type 3 (5-HT₃) receptor inhibitors.⁷⁰ Similarly, multimodal therapy that is a combination of PONV treatment strategies is more effective than a single-treatment strategy.⁷¹ For instance, the combination of propofol anesthesia plus ondansetron has been shown to significantly reduce the incidence of PONV compared with the use of propofol alone (7% versus 22%).⁷² The combination of dexamethasone and ondansetron is more effective than either intervention in isolation and permits the dose of ondansetron to be reduced by 50%.⁷³ A slightly more contentious effect has been the elimination of nitrous oxide, which decreases the incidence of PONV among those undergoing highly emetogenic surgery, with a number needed to treat of only five patients.⁷⁴ However, that meta-analysis also revealed a 2% incidence of awareness under anesthesia if nitrous oxide was omitted.⁷⁴

Other strategies recommended to decrease the rate of PONV include the use of the smallest dose of opioids that still provides adequate pain control and the use of regional anesthesia if possible. The use of nonopioids such as acetaminophen, ketamine, and ketorolac should be considered. Adequate parenteral hydration and avoidance of early postoperative fluid ingestion can reduce the incidence of PONV (see Chapter 4).

Prophylactic Therapy

Ondansetron has been studied extensively and shown to decrease early and late PONV at doses of 50 to 100 µg/kg.⁷⁵ Because the 5-HT₃ receptor antagonists as a group have greater efficacy in the prevention of vomiting than nausea, they are the drugs of first choice for prophylaxis in children. Dexamethasone also is effective in decreasing PONV.⁷⁶ Administration of dexamethasone alone or in combination with other antiemetics can extend the period of effective treatment up to 24 hours. In a systematic review, Steward and associates demonstrated that children who received a single dose of dexamethasone (0.15 to 1 mg/kg) were two times less likely to vomit after tonsillectomy and adenoidectomy than those who did not receive dexamethasone.^77,78 In a randomized, prospective dose-finding study of dexamethasone administered to children undergoing tonsillectomy, there was no difference in the incidence of vomiting after prophylactic doses of dexamethasone between 0.0625 and 1.0 mg/kg (see Fig. 31-5)⁷⁹; a similar trial has not been conducted in the PACU for children who are already vomiting. Before the black box warning was added for droperidol, it was also recommended for prophylaxis of PONV in the United States,⁸⁰ but for medicolegal reasons alone, it is no longer a first-tier antiemetic. Droperidol is commonly used in low doses, which limit extrapyramidal and sedation side effects.

Adequate fluid resuscitation plays in important role in PONV prevention. Children given 10 mL/kg of lactated Ringer’s solution during strabismus correction had more PONV than those given 30 mL/kg (54% versus 22%).⁸¹

The most effective prophylaxis strategy in children at moderate or high risk for PONV is to use combination therapy that includes hydration, a 5-HT₃ receptor antagonist, and a second drug such dexamethasone. Antiemetic rescue therapy should be administered to children who vomit after surgery. An emetic episode more than 6 hours postoperatively can be treated with any of the drugs used for prophylaxis except dexamethasone and transdermal scopolamine.⁸²

Pain Management in the Postanesthesia Care Unit

Acute postoperative pain management strategies are discussed in detail in Chapter 43. A child’s level of pain (or the perception of pain) changes more rapidly in the PACU than in any other unit of the hospital. Frequent and consistent use of pain scores for children of all ages, including those with developmental disabilities, is essential. Many pain scales have been validated for use in children. More important than the specific scale employed, the scale should be used consistently and follow simple principles. For instance, children who are verbal and developmentally appropriate should be encouraged to describe their pain using a self-report scale (e.g., Oucher scale). Young children or those without verbal skills should be assessed using an objective pain behavior scale (e.g., Face, Legs, Activity, Cry, Consolability [FLACC] scale).^85,86 Just as important is the consistent application of protocols to treat pain; treatment of a given pain level should not vary from shift to shift or from one nurse to another.⁸⁷

As with other areas of pediatric pain control, a multimodal approach to postoperative pain is recommended. A plan for pain management should be discussed among the family, surgical team, and anesthesia team before surgery.⁸⁸ Depending on the surgery, the plan may include any or all of the following: acetaminophen, nonsteroidal agents, local anesthesia, nerve blocks, regional anesthesia, clonidine, opioids, patient-controlled analgesia, and patient-controlled epidural analgesia.

Acetaminophen and nonsteroidal drugs act through inhibition of prostaglandins and their metabolites. Most of these drugs are given orally and should be given preoperatively or intraoperatively to be effective in the PACU. Occasionally, they may be indicated in the PACU if they were not administered before arrival. Oral acetaminophen (15 mg/kg) or ibuprofen (10 mg/kg) has been shown to decrease opioid requirements by 20% to 30% after a variety of surgical procedures. Intravenous acetaminophen has become available in the United States for children 2 years of age or older, and it is likely to become a popular analgesic for mild to moderate pain in the PACU and as an opioid-sparing drug.^89,90 The U.S. Food and Drug Administration (FDA) has approved the use of intravenous acetaminophen for children 2 years or older for the treatment of mild to moderate pain or fever. The intravenous dose of 15 mg/kg every 6 hours is recommended for patients weighing less than 50 kg and should be administered over 15 minutes.⁹¹ Studies on intravenous formulations of propacetamol and paracetamol have mostly been conducted in the European Union since drug approval in 2002. Several randomized, controlled studies and meta-analyses have demonstrated efficacy of intravenous administration in adults and children for the treatment of mild to moderate pain or fever.^92,93 It is effective as an adjuvant to other analgesic modalities for moderate to severe pain.⁹⁴

Acetaminophen can also be given rectally in doses of 35 to 45 mg/kg; however, because absorption varies and is delayed (i.e., peak concentration at 60 to 180 minutes after rectal administration), this route is not recommended for use in the PACU.⁹⁵ Because of the pharmacokinetics of the rectal route, a greater interval (6 hours) between doses is recommended, and subsequent doses are reduced (20 mg/kg) so that the total dose per 24 hours does not exceed 100 mg/kg.⁹⁶ There are no data to provide guidance for rectal acetaminophen beyond 24 hours. If a child has received rectal acetaminophen, the first oral dose should be delayed until 6 hours after the rectal dose.

The nonsteroidal antiinflammatory drug ketorolac can decrease opioid requirements by approximately 30%. The recommended dosage is 0.2 to 0.5 mg/kg, which is given intravenously every 6 hours.⁹⁷ Caution is warranted in postoperative children with significant bleeding or a history of renal insufficiency. The manufacturer recommends limiting the total doses to 15 mg for children weighing less than 50 kg and to 30 mg for children weighing more than 50 kg.⁹⁸

Opioids are indicated during the immediate postoperative period for any procedure in which moderate or severe pain is not being managed by other means. Morphine, fentanyl, and hydromorphone have a long history of safe use for infants and children in the PACU. Repeated doses of meperidine are not recommended for children because of the potential for seizures from epileptogenic metabolites (e.g., normeperidine).⁹⁹ Opioid dosing should be initiated according to body weight, physiologic development, underlying medical or surgical conditions, coadministered medications, and severity of pain. The goal should be effective and rapid pain relief. Subsequent dosing of the medications should be titrated based on response to the initial dose. Administration of multiple, small, ineffective doses results in prolongation of pain, stress, and anxiety without improving the safety of care provided. With this caveat in mind, patient-controlled analgesia and patient-controlled epidural analgesia (see Chapters 41 and 43) may be used in the PACU environment, but either intervention should be started only after acute pain has been adequately treated. The small doses administered by patient-controlled analgesia typically are not adequate to completely treat acute postoperative pain and may add to a sense that the method is not working for a given child.¹⁰⁰

Regional analgesia is a common mode of intraoperative pain control in the child that extends into the PACU (see Chapters 41 to 43). The PACU personnel need to know how well it is working, and this assessment can be approached in a systematic manner.

The regional block should be placed in a manner that provides analgesia for the surgical incision site and visceral pain. Evidence that the regional block is effective should first be detected during surgery. If the regional block is effective, the anesthetic requirements are usually reduced. For instance, a caudal block is not effective for a midabdominal incision unless the catheter has been threaded to the region of the incision or relatively large volumes of local anesthetic have been administered. The addition of hydrophilic opioids or clonidine may extend the level of analgesia to some extent over the course of several hours; however, a block that is many dermatome segments away from the site of the surgical incision is unlikely to remain adequate for long. The addition of opioids to an epidural or spinal block increases the risk of pruritus, urinary retention, and emesis. Similarly, visceral pain such as bladder spasms (which have thoracic innervation) or the sore throat after intubation are not attenuated by a lumbar epidural catheter and must be managed by other measures.¹⁰¹

The anesthesiologist must verify that the catheter is in the epidural space. Older children can be questioned about their sensation level using ice or other cold sensation to determine the level of sympathectomy. Preverbal or developmentally disabled patients require some other objective form of confirmation. Previous reports have focused on electrical stimulation through the epidural catheter at the time of catheter placement to determine the level of insertion.¹⁰² Ultrasound methods for detecting epidural catheter placement have been described.¹⁰³ Perhaps most practical in the PACU may be radiographic confirmation of the dermatome level of the tip of the catheter, often with the use of an appropriate contrast material (i.e., epidurogram) to ensure appropriate placement in the epidural space.^104,105 A small amount (<1 mL) of contrast (e.g., Omnipaque 180 or 240) can be infused into the catheter while one radiograph is taken to confirm placement (see Fig. 41-7).¹⁰⁵

Temperature Management

Intraoperative normothermia is key to maintaining a normal temperature postoperatively. Hypothermia is associated with discomfort, bleeding, infections, altered metabolism of drugs, delayed return of cognitive functions, and prolonged recovery.^106–110 Because about 90% of heat loss occurs through the skin, only heat exchange through the skin provides an adequate way of warming children. This method of warming is enhanced by the vasodilation properties of most anesthetic agents. Forced-air warming blankets are the most effective way of maintaining body temperature in children.¹¹¹ Given the vasoconstriction that occurs after anesthesia, attempts at warming are less effective postoperatively than intraoperatively, and most of the detrimental physiologic changes have already taken place. A growing body of literature documents the detrimental effects of hypothermia and shows that it is best when children arrive in the PACU with a normal body temperature.

Infants and children may suffer burns from overly aggressive rewarming measures. This is particularly true for nonverbal children, children who are somnolent, and children who have decreased sensation due to disease or use of regional anesthesia techniques. Recommendations from manufacturers and recent literature should be carefully reviewed before instituting routine use of warming devices.

Discharge Criteria

The recovery process and discharge criteria vary from institution to institution. Various criteria are used to determine readiness for discharge from the PACU. Some institutions require an assessment by a physician before discharge for all patients, but others require an evaluation only if routine discharge criteria are not met. The modified Aldrete scale is the most common system used to assess discharge readiness, but specific criteria depend on the particular situation or environment to which the child will be discharged. For example, a child with a slight degree of postextubation croup or stridor may be discharged for monitoring on a pediatric floor or ICU, but the same child is not discharged to parental care and a 2-hour drive home. The criteria for discharge of children to a general inpatient setting are summarized in Table 46-6. For outpatients, these criteria hold, and the additional criteria outlined in Table 46-7 usually must be met before discharge.

TABLE 46-6 Discharge Criteria for Inpatients

TABLE 46-7 Discharge Criteria for Outpatients

Traditionally, pediatric patients have been allowed to recover in a first-stage recovery unit until the airway was considered stable, consciousness is regained, baseline motor activity is confirmed, vital signs are stable, and oxygen saturation values are stable in room air (or at baseline) without respiratory support (unless needed at baseline). Pain should be well controlled. Children then can be transferred to a second-stage recovery unit, where more complete recovery takes place with a reduced nurse-to-child ratio, until children have met criteria for adequate hydration, minimal emesis, appropriate wound status, good vital signs, and appropriate ambulation and mental status.

The requirements for children to eat, drink, and void before leaving the secondary recovery area significantly delay discharge. Efforts should be made to reinstate volume homeostasis during surgery, negating any physiologic imperative for oral intake in the immediate postoperative period. Postoperative maintenance fluids should consist of isotonic rather than hypotonic solutions for those expected to remain as inpatients to reduce the risk of hyponatremia (see also Chapter 8).¹¹² Other than children who are at high risk for urinary retention (e.g., history of urinary retention, urethral surgery), there is little evidence that discharge before voiding results in readmission for voiding problems, and this requirement is therefore no longer part of standard discharge criteria.¹¹³ Children who have received a caudal block for surgery are likewise at low risk for urinary retention as long as opioids have not been added to the caudal medication.¹¹⁴

Although there are few data on the current status of recovery processes across the country, there appears to be a trend toward one-stage (fast-track) recovery for pediatric outpatients.^115,116 This process allows selected children to bypass the first-stage recovery and go directly to the second-stage unit based on appropriate level of consciousness, physical activity, vital signs, respiratory status, and pain control (Table 46-8). This approach has proved successful and quite safe, although appropriate attention to issues such as pain control must be addressed when initiating such a program.

TABLE 46-8 Discharge Criteria for Fast-Tracking

MAP, Mean arterial pressure; PACU, postanesthesia care unit.

^*Pediatric patients must score 14 to bypass the phase 1 (PACU) recovery unit to be admitted directly to the step-down care unit.

From White PF, Song D. New criteria for fast-tracking after outpatient anesthesia: a comparison with the modified Aldrete’s scoring system. Anesth Analg 1998;88:1069-72.