Pediatric anesthesia

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Chapter 11 Pediatric anesthesia

Fatima Ahmad, MD

Pediatric ambulatory surgery has a long-standing record of safety, as children generally represent a healthy cohort of the patient population. However, some children have complex syndromes and major morbidity. Additionally, there are many pediatric surgical procedures that do not require postoperative hospitalization and can be done efficiently in an ambulatory set up. The success is highly dependent on a team approach where child life specialists, perioperative nurses, surgeons, and anesthesiologists all work together to achieve the best results by making the experience comfortable, non-threatening, and pleasant for both the parents and the children.

Psychologically also, ambulatory surgery is more suitable for children as they recover from surgery in the comfort and security of their home environments as compared to more stressful inpatient hospital surroundings.[1] The downside of efficiency and cost-effectiveness of pediatric ambulatory surgery is the recruitment of increasing numbers of patients with chronic medical problems. Careful patient selection by the anesthesiologist is crucial to continue this record of safety. Although the incidence of life-threatening complications in this population is low, some perioperative issues may require overnight hospital admission.

Pediatric anesthesia is considered a distinct subspecialty due to significant anatomic and physiological differences between children of different ages and adults. The most important anatomic characteristics in children that are relevant to anesthesia are related to airway. Their large tongue size relative to oral cavity can easily lead to airway obstruction in the presence of sedation, as natural muscle tone may be reduced. Being obligate nose breathers, any unfavorable upper airway conditions like inflammation or excessive secretions can make the work of breathing difficult. The pliability and smaller diameter of the trachea makes it more prone to occlusion if the neck is overly extended or flexed. Even a small amount of swelling of tracheal mucosa can lead to significant obstruction in airflow. The selection of an appropriately sized endotracheal tube and ensuring an airleak around the tube cuff is important for this reason. Another measure is to consider using the LMA whenever appropriate. This can help avoid tracheal irritation, although increased attention should be given to avoiding abundant pharyngeal secretion or gastric regurgitation.

Physiologically, the pediatric cardiovascular system is prominent by its many characteristics that differ from adults. The pediatric cardiac compliance is low as compared to adults, so cardiac output is highly dependent on the heart rate. Bradycardia in a child usually results from hypoxia, and by lowering cardiac output, it can create a dangerously hypoxic low output state. In addition, with the rib cage being unable to increase the anteroposterior diameter and small, overcrowded abdomen hindering the diaphragm’s ability to move downward, the pulmonary reserve becomes very limited.

Children are also easily susceptible to hypothermia due to limited fat reserves and larger surface area to volume ratio. Special efforts are mandatory to keep them normothermic.

Pharmacokinetics of various drugs differ significantly in children as compared to adults. This may be due to immaturity of enzyme systems and clearance mechanisms and altered protein binding during the first 1–2 years of life, leading to increased bioavailability and prolonged half-life of certain drugs. In children above this age, the dose need of hypnotic agents and inhalational agents is increased as compared with adults, whereas the need for opioids is approximately similar per kg of weight.

Due to some of the factors mentioned above, the safe provision of anesthetic care is highly dependent on the clinical skills of the anesthesiologist. Credentialing criteria for personnel providing pediatric anesthesia at free-standing surgery centers may differ from hospital setups as situations differ with respect to immediate availability of skilled help. The American Society of Anesthesiologists Statement on Practice Recommendations for Pediatric Anesthesia[2] clearly delineates the criteria required to be privileged to perform pediatric anesthesia. In addition, PACU nurses skilled in taking care of pediatric patients should be available on facility. PALS certification for these nurses is highly recommended. In addition to skilled personnel, the facility should be equipped with state-of-the-art specialized pediatric equipment and drugs. These include items for airway management, positive pressure ventilation systems, and temperature maintenance devices, intravenous fluid administration supplies, monitoring equipment per ASA standards, specialized difficult airway management devices, and pediatric crash carts, among others.

Common pediatric ambulatory surgeries

The commonly performed procedures in ambulatory surgery centers are listed below.

ENT surgeries, i.e., myringotomy and tube insertion, tonsillectomy, adenoidectomy, frenulectomy.

Dental surgeries.

General and urologic surgeries, i.e., inguinal herniorrhaphy, circumcision, orchiopexy, hypospadias repair.

Gastrointestinal endoscopies.

Ophthalmologic procedures, strabismus repair.

Orthopedic surgeries on extremities.

Plastic cleft lip repair and removal of skin lesions.

Patient selection and commonly faced challenges

Similar to preoperative evaluation of patients getting surgeries in the hospital setup, outpatient pediatric evaluation should be focused on a detailed health assessment, physical examination and necessary lab work.

In many surgery centers, a preliminary telephone screening is done by a nurse as soon as the surgery is booked and the anesthesiologist reviews the data. Most of the children are ASA physical status 1 or 2 and this initial review is sufficient. For ASA physical status 3 patients, this initial screening helps to determine if further referral to a primary physician is indicated for optimization for their clinical conditions. On the day before surgery they are called again to reinforce fasting guidelines and to determine if there is a change in their conditions. These calls help to reduce cancellations on the day of surgery when the patient is thoroughly evaluated again by the anesthesiologist performing the case. Some of the common controversies and challenges faced in pediatric population are discussed below.

Upper respiratory tract infection (URI)

Children with symptoms of URI have increased risk of respiratory complications including laryngospasm,[3] bronchospasm,[4] and postoperative oxygen desaturation.[5] The URIs can result in airway hyperactivity that lasts for up to 6 weeks after infection.[6] Generally, afebrile patients with uncomplicated URI, clear secretions, and no major comorbid conditions are safe to proceed.[7] The sick febrile child with purulent secretions, persistent cough, lethargic appearance, and lower respiratory symptoms, such as wheezing, should, if possible be postponed for at least 4 weeks,[6] or referred to an inpatient setting if the surgery is needed sooner. In patients with nasal congestion and slight non-productive cough for procedures requiring intubation, other risk factors such as history of asthma, prematurity, parental smoking, and surgery on the airways should be taken into account. The anesthetic management should focus on minimizing secretions, adequate hydration, and avoidance of airway stimulation under light anesthesia.[6]

Patient age and history of prematurity

Full-term infants can be done as outpatients once they are 2–4 weeks of age.[8] By this time, symptoms of physiologic jaundice have decreased, ductus arteriosus has closed, pulmonary vascular resistance has reached a normal level and risk of postoperative apnea has declined. Preterm infants have increased risk of apneic events in the immediate postoperative period and require at least 12-hour monitoring for up to 60 weeks of post-conceptual age.[9] The risk is increased if there is a history of episodes of apnea at home, anemia, and neurological and chronic lung diseases.[10]

Children with obstructive sleep apnea (OSA)

OSA is mostly seen in children presenting for tonsillectomy and adenoidectomy. It is characterized by complete or partial upper airway obstruction during sleep, resulting in hypoxia and hypercarbia and pulmonary hypertension in severe cases. The severity of hypoxemia, hypocarbia, and apnea/hypopnea events on polysomnographic testing relates to increased risk of postoperative respiratory complications. All children with OSA may not have undergone polysomnography and screening tools can be developed according to ASA guidelines.[11] These should focus on BMI, neck circumference, anatomical nasal obstruction, craniofacial abnormalities, tonsillar hypertrophy, history of loud snoring, breath-holding (apnea) during sleep, interrupted sleep, and daytime sleepiness. The risk of postoperative respiratory complications, including fatal events, is higher in children with severe OSA.[12]

These children have increased sensitivity to anesthetic agents, including opioids. They are usually not good candidates for outpatient surgeries, especially tonsillectomy and adenoidectomy procedures, as prolonged continuous monitoring may be required. Children younger than 3 and 2 years of age presenting for tonsillectomy and adenoidectomy, respectively, are also at higher risk for respiratory complications and should not be done in an ambulatory setting.[13]

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Jan 21, 2017 | Posted by in ANESTHESIA | Comments Off on Pediatric anesthesia
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