The pediatric postanesthesia care unit (PACU) is a noisy and chaotic environment. Nurses are attempting to calm crying toddlers, parents are being educated, physicians are being summoned for discharge orders, and the phones ring continuously with reports of available inpatient beds. Monitor alarms are artifactually ringing, and entire families gather in their child’s room to watch the latest reality television show. But lying beneath the din, some children are in pain, or nauseated, or unconsciously screaming for no reason whatsoever. Some children may even become deeply hypoxic. Such is the daily routine in a busy children’s hospital PACU.
Routine Postoperative Care
Each child’s vital signs shall be fully monitored until they have regained their baseline neurologic and cardiorespiratory status. Continuous pulse oximetry is vital because the most important postoperative complication is upper airway obstruction, which rapidly leads to hypoxemia. Upper airway obstruction can be detected even faster using continuous capnography, but most PACUs do not yet use the technology to monitor end-tidal carbon dioxide in an awake and spontaneously breathing child. Continuous electrocardiogram (ECG) monitoring is only necessary in select cases, depending on the patient’s clinical status. The child’s temperature should be obtained on arrival in the PACU and monitored at regular intervals until discharge. Hypothermia is common in small children who may require a warming blanket postoperatively. Hyperthermia is occasionally seen in some children as a result of iatrogenic overheating in the operating room (OR), or other unknown factors related to the surgical procedure. It is never an initial presenting feature of malignant hyperthermia, unless accompanied by other signs and symptoms of hypermetabolism. Supplemental oxygen administration should be guided by pulse oximetry. In some centers, children are discharged from the phase 1 acute PACU to the phase 2 recovery area (day surgery unit) after regaining consciousness and maintaining stability of vital signs without oxygen supplementation. In other centers, these two phases are combined into one area where the patient stays until discharge home or to an inpatient care area.
Discharge Criteria
Many pediatric centers have established specific physiologic parameters that classify the stages of emergence after general anesthesia. These criteria are used to determine readiness for discharge to the hospital ward or to home. Most pediatric centers use discharge criteria first described in 1975 by David Steward, who modified the standard Aldrete recovery score for use in children ( Table 31.1 ).
| Patient Sign | Ocular Effects | Score |
|---|---|---|
| Consciousness |
|
|
| Airway |
|
|
| Movement |
|
|
The Steward score uses levels of consciousness and airway patency, to a total score of six used to establish appropriate readiness for discharge. However, the relationship of this score to other outcome variables, such as oxyhemoglobin value, has not been established. In most pediatric centers, there are additional discharge requirements that include adequate hydration, pain control, and control of nausea and vomiting. Gradual oral intake of fluids is allowed but not encouraged or required for discharge home. Urinary voiding is also not required for discharge home unless specified by the surgeon based on the procedure.
Postoperative Complications
Nausea and Vomiting
Postoperative nausea and vomiting (PONV) are probably the most common complications after general anesthesia in children. Although PONV is not life-threatening, it causes profound discomfort to the child and their family and has been demonstrated to be a primary factor in patient dissatisfaction. Certain types of procedures, such as ENT, ophthalmologic, and orthopedic, increase the risk for PONV. Anesthetic risk factors include use of inhaled anesthetics and opioids. Patient-related factors include previous PONV, history of motion sickness, and age greater than about 3 years. The incidence of PONV can be decreased by use of propofol instead of inhaled agents, avoidance of opioids, use of regional anesthesia, limiting postoperative oral intake, increasing intravenous hydration, and prophylactic administration of antiemetic medications. Combination (multimodal) therapy with different classes of antiemetics more successfully prevents PONV than one type of antiemetic alone. Intraoperative evacuation of gastric contents does not reduce PONV in adults but has not been studied in pediatric patients. Children with protracted PONV are admitted to continue IV access to provide fluids and analgesics.
Serotonin Antagonists
Serotonin (5-HT 3 ) antagonists significantly reduce the incidence and severity of vomiting in the first 24 hours after surgery and are the first-line medications because of their favorable benefit-to-risk ratio. Although there are several different varieties of serotonin antagonists, ondansetron is the oldest and most widely studied in children and is available as a generic preparation. Newer variants may have a longer duration of action than ondansetron. Doses of ondansetron probably do not need to exceed 0.05 mg/kg. Children that develop PONV despite receiving ondansetron prophylaxis usually do not respond to additional doses but may respond to another type of serotonin antagonist.
Dexamethasone
Dexamethasone is a glucocorticoid steroid that effectively prevents and treats PONV. Combination therapy along with a serotonin antagonist is more effective than when either is administered alone, and is indicated in children at high risk for PONV. Dose ranging studies demonstrate inconsistent results. Most pediatric anesthesiologists use a dose of 0.1 to 0.5 mg/kg. Side effects of dexamethasone include hyperactivity, insomnia, and increased appetite. Dexamethasone may cause tumor lysis syndrome in patients with leukemia, and thus, should be avoided in these patients.
Nonpharmacologic Treatment of PONV
Acupuncture, acupressure, and electrical stimulation at the Nei-Guan (P6) point on the wrist (slightly proximal to the distal skin crease of the wrist on the ulnar side) have been shown to decrease the incidence of PONV in children but these methods have not been adopted in most centers.
Stridor
Inspiratory stridor in the postoperative period (also called postintubation or postextubation croup) is an indication of upper airway swelling, usually below the glottis. It is presumed to be caused by tracheal mucosal edema related to pressure from a cuffed or uncuffed endotracheal tube. The exact location of the swelling is unknown but presumed to be located at the level of the rigid cricoid ring. In a past era (before the 1990s), the incidence of postintubation croup was about 1%, but in the present era, it is much less than that. This decrease is largely because of the use of nonreactive endotracheal tubes, recognition of keeping the endotracheal tube cuff pressure low, and increased use of the laryngeal mask instead of an endotracheal tube. When it occurs, it rarely causes oxyhemoglobin desaturation. If the child with stridor underwent surgery of the upper airway or neck, immediate surgical consultation is warranted. Initial management strategies include administration of supplemental oxygen, repositioning the head or neck, administration of dexamethasone (if not already given for PONV prophylaxis), and, if severe, or if oxygen saturations are declining, nebulized racemic epinephrine. If stridor is progressive and associated with a worsening SpO 2 despite the aforementioned therapies, tracheal intubation is indicated, and ENT consultation is required to help with diagnosis and further management. In mild cases that require minimal intervention, the child can be discharged home when the stridor has abated, as long as there is no evidence of oxyhemoglobin desaturation (e.g., below 96%) without oxygen supplementation.
Inhaled racemic epinephrine (supplied as a 2.25% solution) provides topical vasoconstriction and shrinks edematous tracheal tissue. The dose is 0.05 mL/kg (maximum dose 0.5 mL) diluted in 3 mL of normal saline. It is administered as a nebulized solution every hour if needed, based on clinical symptoms and sympathomimetic side effects. Administration of racemic epinephrine usually constitutes mandatory overnight or prolonged hospital observation because of its limited duration of effects and possible recurrence of airway obstruction.
Emergence Delirium
Emergence delirium (ED) is a state of inconsolable agitation shortly after waking up from general anesthesia. It is characterized by unremitting crying, tachycardia, pupillary dilatation, disinterest in drinking, and the inability to be consoled by the presence of parents. Although essentially a benign condition, it is extremely disconcerting to parents and even PACU staff. The Pediatric Anesthesia Emergence Delirium (PAED) scale was created and validated to measure ED in children, and has mainly been used as a research tool. It consists of five reliable indicators of ED: (1) lack of eye contact with the caregiver; (2) nonpurposeful actions; (3) lack of awareness of surroundings; (4) restlessness; and (5) inconsolability.
The precise cause is unknown but is thought to represent a state of residual anesthetic agent in the brain that causes disinhibition. “Stormy inductions” and maintenance of general anesthesia with sevoflurane or desflurane increase the incidence of emergence delirium. Administration of intraoperative propofol, fentanyl, morphine, and α 2 -adrenergic agonists (e.g., clonidine and dexmedetomidine ) have been shown to decrease the incidence of ED. Once ED occurs, it is treated by having the child fall asleep by reducing external stimuli (e.g., lights out) and swaddling the child in a warm blanket. This may be facilitated by administration of small amounts of morphine, propofol, or dexmedetomidine. Once asleep, these children will typically awaken in about an hour in a more normal state of grogginess.
The most important aspect of emergence delirium is to differentiate it from serious events, such as hypoxemia and pain that need prompt treatment.
Hyponatremia
In some children, postoperative dilutional hyponatremia (<125 mEq/L) results from hypotonic fluid administration combined with high antidiuretic hormone (ADH) levels. Acute hyponatremia can lead to the development of cerebral edema. Symptoms include confusion and lethargy but can be as severe as seizures, coma, or death if sodium levels drop below 115 mEq/L. Because postoperative hyponatremia is associated with the use of hypotonic intravenous maintenance fluid, only isotonic fluids are recommended in children in the immediate postoperative period, unless otherwise indicated by the clinical situation.
References
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