The Practice of Pediatric Anesthesia

Published on 05/02/2015 by admin

Last modified 22/04/2025

Print this page

This article have been viewed 1380 times

1 The Practice of Pediatric Anesthesia

Charles J. Coté, Jerrold Lerman, Brian J. Anderson

IN THIS CHAPTER WE outline the basis of our collective practice of pediatric anesthesia. These basic principles of practice can be applied regardless of the circumstances; they provide the foundation for safe anesthesia.

Preoperative Evaluation and Management

Parents and Child

Anesthesiologists must assume an active role in the preoperative assessment of children. Ideally, the anesthesiologist performing the preoperative evaluation will also anesthetize the child. A complete medical and surgical history; family history; medical record review; evaluation and review of laboratory, radiologic, and other investigations; and physical examination are performed on every child who is to be anesthetized (see Chapter 4). When appropriate, the child should receive preoperative medical therapy to optimize his or her medical condition or conditions (e.g., children with seizure disorders or reactive airway disease) before receiving anesthesia. In addition, the emotional state of the child and family must be considered and appropriate psychological and, if necessary, pharmacologic support provided. The anesthesia team, working in concert with surgical colleagues, nursing, and child-life specialists, should find appropriate and creative techniques (e.g., use of videotapes, booklets, hospital tours, and trained paramedical personnel) to prepare the child and family. The marked increase in the number of outpatient surgical procedures has reduced the time available for interaction among the anesthesiologist, the family, and the child. Despite this reduced contact time, these support techniques should not be neglected.

Familiarity with a child’s clinical and psychological status as well as the parental concerns is essential to delivering quality anesthesia care. To achieve the very best outcome for each child, it is essential to meet with the child and the parents (or caregiver or legal guardian) together and establish rapport preoperatively. There are many developmental issues that surround the hospital experience: for example, teenagers fear loss of control, awareness, and pain; younger children fear mutilation from their surgery; and toddlers fear separation from their parents (see Chapter 3). However, for children who are old enough to understand (usually age 5 years and older), it is reasonable to explain in simple terms what anesthesia involves and what will transpire on entering the operating room. It is vital to speak directly to the child because he or she is the person having the surgery. Children at the age of reason have the same fears as adults, but have greater difficulty articulating them. It is important to explain the differences between “sleep” from anesthesia medicine and the sleep they get at home. Even if they undergo anesthesia for hours, they will feel as if they were unconscious for only the time it takes to blink the eyelids once. Many children are also fearful of awakening during the surgery and others are fearful of not awakening at the end of surgery. Children require reassurance that they will not feel anything during surgery, that they will not wake up during the procedure, and that they will awaken at the conclusion of the surgery.

The possibility of postoperative pain and the relief the child will receive in the form of nerve blocks and analgesics must be clearly presented to the child and the parents. It is also important to explain to the child and the family what they can anticipate on entering the operating room and to explain the special monitoring you, as the anesthesiologist, will provide for the child. A simple explanation of the monitors can be very reassuring to parents and interesting for many children. For example, the pulse oximeter can be described as a “Band-Aid−like device” that lights up red and measures the oxygen in the bloodstream during anesthesia and recovery; the blood pressure cuff can be characterized as an “arm hugger” or “muscle tester”; and the electrocardiogram leads can be called “little sticky things that don’t hurt so we can watch the heart beat.” Simple descriptions of the measurements may also be soothing. For example, you can say: “We measure the oxygen you (your child) are (is) breathing, we measure the amount of the anesthesia medicines you (your child) are (is) breathing, and we measure the carbon dioxide you (your child) are (is) breathing so as to ensure that your (your child’s) breathing is just right throughout the anesthesia.” Sometimes asking teenagers if they have studied carbon dioxide in school science class helps them to better understand the monitors and provides reassurance, as well as making it more interesting. The detail with which this is presented will vary from family to family and child to child as well as with the anesthesiologist’s understanding of the needs of the child and family. By the end of the interview, however, the child and the parents should understand that you will be providing the quality of care that ensures the child’s safety during anesthesia, thus reducing the child’s and parents’ anxiety. Explanation is also needed to describe how anesthesia will be induced, although the degree of detail used will again depend on the developmental level of the child. For young children, one can describe a plan to breathe “laughing gas” through a flavored mask, with a flavor that he or she chooses. Older children can be given the option of an intravenous (IV) induction, with nitrous oxide by mask to establish IV access painlessly; or if they are afraid of needles, they might be given the option of an inhalational induction.

If parents are to be present during induction, it is essential to describe to them how they can assist in comforting the child and prepare them for what they might observe and experience to avoid any misconceptions. Parents should not be pressured into feeling that they must be present for induction. It must be clear that, if at any time during the induction there is a new or additional risk to the child, they may be asked to leave the operating room and will be escorted to the parent waiting room. Remind them that their presence at induction is for their child’s benefit and is a privilege, not a right. Thus, if there are issues with a difficult airway, if a rapid induction of anesthesia is needed, or if the child is very young, it would be inappropriate for the parents to be present and not in the child’s best interest for physicians and nurses to be distracted at a time when everyone’s attention needs to be focused on the child.

It is helpful and essential to explain to the parents specific changes in the child that might be observed at the time of anesthetic induction:

1. As your child is anesthetized, the eyes may roll up: “You might see your child’s eyes roll up and this is completely normal and happens to all of us when we fall asleep; it is just that we are not looking for it.”

2. “As people fall asleep they often make snoring noises and other noises from their throat; if your child does this it is completely normal.”

3. “As the anesthetic reaches the brain, the brain sometimes gets excited and causes movement of the arms and legs that are without purpose, or it may cause them to turn their head from side to side. This means the anesthetic is having its effect and even though your child appears to be partly awake, he (or she) has received enough anesthesia to ensure that he (or she) does not remember this.”

4. “If your child becomes frightened, we will increase the amount of the anesthesia medicine rapidly and calm your child as quickly as possible.”

5. If the child is to have an IV induction, then informing the parents that the child might suddenly look pale and that the start of anesthesia will be very rapid is also helpful so as to avoid confusion about what the parents will observe.

These preemptive explanations are important to undermine the parents’ anxiety at a time when you need to focus on the child. It is common for parents to decline to be present during induction once they hear these explanations. Finally, it is prudent to reassure the parents that for surgeries that are emetogenic and in children who have been or are prone to emesis, that appropriate prophylactic therapy will be administered before the child recovers. Similarly, explain to them that if pain is anticipated, it will be managed aggressively in the operating room and in the recovery room. Anesthesiologists can provide valuable assistance in this respect because of their knowledge of the pharmacology of sedative and opioid medications (see Chapter 6), as well as their ability to perform neuraxial and peripheral nerve blocks (see Chapters 41 to 43). The possible need for postoperative intensive care, including assisted ventilation, should be anticipated and fully discussed with the parents and child (if the child is of an appropriate age). If special monitoring is required in the operating room or postoperatively, this should be explained and the child assured that the IV catheters, airway devices, and all invasive monitoring devices will be placed after induction of anesthesia to avoid causing discomfort and will be removed as soon as the child’s postoperative condition permits.

The anesthesiologist who sits down, who speaks slowly and clearly while answering questions, and who is neither distracted nor in a rush to leave, presents a very different image to the child and parents from the anesthesiologist who stands tapping his or her toes, speaks quickly, and has one foot pointed toward the door. Details regarding the anesthetic should not be recited in a cold and technical manner, but rather with communication that addresses the parents’ and the child’s questions and concerns. This dialogue is frequently afforded too little time, leaving the parents and child insecure and apprehensive, their questions unanswered. Body language is especially important during this preoperative interview. If the family speaks a different language than the anesthesiologist, then a medical interpreter should be sought.

The Anesthesiologist

Anesthesiologists must fully understand the proposed surgical or investigative procedure to facilitate the planning of an appropriate level of monitoring and selection of anesthetic drugs and technique. The anesthesiologist must anticipate the needs of the surgeon or proceduralist in terms of positioning the child, the need for or avoidance of muscle relaxants, considerations regarding specific procedures (e.g., the surgeon’s need for motor and sensory evoked potentials may influence choices of anesthetic technique), IV fluid and blood product management (see Chapters 8 and 10), as well as the need for strategies to alleviate perioperative pain and anxiety. For complex cases, the anesthesiologist and surgeon should formulate a plan preoperatively and explain the plan to the parents and child. All important medical issues that require clarification should be investigated during the preoperative evaluation and planning process. It is useful to discuss your concerns with the appropriate medical consultants (e.g., the neurologist for the management of seizure medications in the perioperative period, the hematologist for the child with hemophilia, and others as indicated). To maximize the benefit from these consultations, it is important to focus on the specific anesthetic or medical issue of concern. Consultant recommendations must be carefully reviewed and should reflect the consultant’s understanding of the anesthesia process and what it is that you require regarding the child’s medical condition that will assist you in the delivery of anesthesia (see Chapters 11, 14, 22, 25, 26, and 28).

All children should be fasted preoperatively. Infants must receive special consideration; prolonged abstinence may lead to dehydration or hypoglycemia (see Chapters 4 and 8). Children may surreptitiously circumvent the preoperative fasting orders, especially if the period of fasting is prolonged or other children in the vicinity are in possession of food. One must always be prepared for the possibility of a full stomach and its sequelae. For example, the risk of pulmonary aspiration of gastric contents is increased in some children (e.g., who are obese and who had previous esophageal surgery, difficult intubation, or hiatal hernia). In these children, the anesthetic management should be modified to minimize the risk of regurgitation and aspiration. Preoperative consideration must be given to proper psychological support, appropriate premedication, and the timing of the premedication (see Chapters 3 and 4). Psychological support of the child and parents must never be neglected, no matter how calm they might appear. Premedication may be administered on the ward or in the waiting area; however, once any medication is administered, the child must be observed for compromise in cardiopulmonary function. If the child is premedicated on the ward, transport to the operating room must be undertaken with caution and with appropriate monitoring. A critically ill child must be accompanied by skilled staff who will ensure continued infusion of vasoactive medications and who are skilled in the management of any emergencies that could arise during transport (see Chapter 38). In some, premedication may be omitted because of the critical nature of a child’s illness or because a child is especially cooperative.

Informed Consent

The benefits and risks of the anesthetic procedure must be presented in clear, easily understood terms. At the same time, it is important not to present this in a manner that unduly frightens the child or parents. The details of such a presentation will depend, in part, on the severity of the underlying medical and surgical conditions and how these affect anesthetic management and the planned procedure. Thus, risk can be presented in general terms, such as:

“The risks of anesthesia are generally proportional to the health of the child. For example, if a child has a heart, lung, or kidney disorder, etc., then the risk from anesthesia is increased. In your child’s case these are our concerns” (and then elaborate the particular patient’s issues, such as reactive airway disease, apnea of prematurity, etc.). “Knowing these problems ahead of time may reduce the anesthetic risk for your child because we can modify our anesthetic prescription according to your child’s specific needs. However, there is always the possibility of allergic or unusual responses to anesthetic medications that we cannot predict, and that is why I shall carefully observe and monitor your child as I have described.”

We are designing the “anesthetic prescription” specifically for the particular needs of their child, and this notion should be described exactly this way to the parents. We are physicians and not technicians, and just as the pediatrician writes a prescription for antibiotics, anesthesiologists write the treatment prescription for anesthesia and administer it.

If a child is critically ill or has a disease process that is an immediate threat to his or her life, then this must be explained to the family. If a parent asks about the mortality risk, then all one can say is that the mortality related to anesthesia in most advanced countries is very small, less risky than crossing a busy thoroughfare on foot. Statistically, the incidence varies from one in several hundred thousand for healthy children undergoing routine procedures to a much greater rate for those who are critically ill. Nonetheless, the mortality for any specific child cannot be predicted with certainty. Recent concerns regarding possible anesthetic agent–induced neurotoxicity (see Chapter 23) has become a common question from parents of neonates or toddlers. Again, reassurance regarding the lack of substantive human data, the importance of our monitors, and our experience will help allay their concerns.

Operating Room and Monitoring

For the anesthesiologist to successfully carry out a proposed anesthetic plan, the child’s medical record must be examined for pertinent information before induction of anesthesia. For children who have already been assessed preoperatively, the record should be reviewed again for new information that may have been added since the initial evaluation. It is most important that the child’s identification bracelet is checked, especially if the anesthetizing team is different from the preoperative evaluation team. A “time-out” and checklist for nurses, surgeon, and anesthesiologist to confirm the child’s name, the planned surgical procedure, and the site of the surgical procedure (right or left side or bilateral); airway concerns; the need for prophylactic antibiotics; allergies and anaphylaxis; and availability of special equipment and large IV access are also reviewed. This review constitutes a vital safety net that we provide in the operating room (Fig. 1-1). All equipment for induction and maintenance of anesthesia, including suction and all necessary monitoring devices, must be functioning and reliable (see Chapter 51). Equipment must be checked by the anesthesia team before induction of anesthesia.

FIGURE 1-1 WHO Surgical Safety Checklist.

(From World Health Organization, Geneva, 2009. Available from: http://www.who.int/patientsafety/safesurgery/en/)

The monitoring should be appropriate for the child’s clinical condition and surgical procedure. In every situation, basic monitoring is essential; to this are added special monitoring devices as they become necessary. The basic monitors are the anesthesiologist’s eyes, ears, and hands, which confer the ability to observe a child’s color and chest movements, to listen for heart tones and breath sounds, and to palpate the arterial pulse and temperature of the skin. A precordial or esophageal stethoscope is a very useful and simple device that allows constant assessment of heart tones and the quality of breath sounds even when our attention is focused away from physiologic monitors. All children, except those undergoing the briefest noninvasive procedures, should have IV access to allow for fluid administration and to provide a route for rapid and predictable drug administration. If IV access is already in place, it is essential to ensure its functionality and size before anesthesia is induced. Fluid replacement with balanced salt solution is particularly important in children who have undergone prolonged fasting or who have ongoing third-space losses, although glucose-containing solutions may be preferable under specific circumstances (see Chapter 8). Continuous monitoring of the electrocardiogram, temperature, inspired oxygen concentration, oxygen saturation, expired carbon dioxide, and intermittent blood pressure determination are considered routine. Expired carbon dioxide monitors (especially those that display the waveform) and pulse oximetry are extremely important in the early detection of potential anesthetic-related events that, if undetected, could result in serious morbidity or mortality. Identifying the anesthetic agent and monitoring its concentration breath by breath is also helpful but not mandatory. The role of wakefulness-monitoring devices in children remains unestablished, especially in children who are younger than 2 years of age (see Chapters 6 and 51). Near infrared spectroscopy is being used increasingly during cardiac surgery; it provides a useful monitor of cerebral (i.e., organ) oxygenation.

Invasive hemodynamic monitoring (e.g., direct arterial blood pressure, central venous pressure) may be required for major surgery if extensive blood loss or major fluid shifts are anticipated, or if a child is medically unstable. Urine output provides indirect data of the intravascular volume and organ perfusion in the presence of normal renal function. Monitoring urinary output is particularly useful for prolonged operations, for procedures involving major blood loss, when there is the potential for rapid or massive blood loss, when wide variations in blood pressure and fluid balance can be anticipated, or during induced hypotensive anesthesia. In general, if a particular variable would be monitored in an adult, then the same approach should be adopted for a child.

Invasive monitoring procedures are sometimes forsaken in a child because inexperience with pediatric techniques causes the anesthesiologist to dismiss these procedures as being “excessive.” These monitors, however, allow the accurate measurement of blood pressure, cardiac output, filling pressures, and cardiac and pulmonary function. In turn, they provide a safe mechanism for assessing the response to pharmacologic interventions, as well as the responses to administration of blood products, fluids, and vasoactive medications (see Chapter 48).

A cautionary note: With increased sophistication in monitoring, anesthesiologists have become more distanced than ever from their patients. Relying totally on mechanical monitoring devices to detect clinical abnormalities is dangerous. The focus must always be on the child and the surgical field. Monitors may fail, and if the anesthesiologist focuses attention on the monitor in an effort to interpret it, rather than attending directly to the child, the child may suffer. This is the reason that a precordial stethoscope is so useful; strong heart sounds in the face of failed monitors provides some degree of assurance that the child is not in severe trouble. Disabling monitor alarms for an extended period of time is a serious breach of safety and practice standards. One of the editors knows of a child for whom all monitor alarms and sounds were disabled during anesthesia, who was discovered dead at the conclusion of the procedure after an unrecognized, unintended tracheal extubation. Most importantly, the tone of the pulse oximeter should be audible by everyone in the operating room to detect decreasing oxygen saturation.

Induction and Maintenance of Anesthesia

Significant differences in the physiology and behavior of a child, especially a neonate, in comparison with an adult, mandate that the anesthesiologist not consider a child merely a small adult. In an infant, the rate of uptake of inhalation anesthetic agents is more rapid than in an adult. An infant’s response to most oral and IV medications is also different; therefore, if changes need to be made, the inspired concentration of an inhalation agent should be adjusted more gradually and the doses of medication diluted and titrated more carefully than in older children and adults (see Chapter 6).

In principle, the approach to an anesthetic procedure in a child is similar to that in an adult. In practice, however, it is often advisable to modify the sequence of application of monitoring devices. In a relatively stable child, induction of anesthesia may proceed with only a pulse oximeter and possibly a precordial stethoscope, while the remaining monitors are applied after induction. This sequence often avoids a prolonged preparation phase during which a child may have more time to become anxious and distressed. In critically ill children, however, omitting some monitors in order to avoid upsetting them is imprudent, especially if it compromises the child’s well-being during anesthesia. In a struggling, upset child, some monitors may display accurate measurements before induction of anesthesia, whereas others do not. The pulse oximeter may not provide reliable measurements in a struggling child until the finger or toe is relaxed.

Clinical Monitors

In children as in adults, monitoring begins with the basic observations of a child’s general condition: the heart rate, blood pressure, respirations, and temperature. The most important aspect of basic monitoring consists of using the senses of sight, hearing, and touch to integrate all the data provided by patient observations and the monitors.

Sight

Constantly observing a child’s chest excursions (depth and symmetry), the color of the nail beds, oral mucosa, and capillary refill provides vital information about the adequacy of ventilation and perfusion. Observation of the surgical field provides an immediate indication of the extent of fluid shifts and blood loss, the color of the blood in the surgical field, evidence of muscle relaxation, depth of anesthesia, and various physiologic problems that may occur during the surgery (e.g., surgical retraction causing venous obstruction).

Hearing

Constantly listening to the pitch of the pulse oximeter as well as the heart tones and breath sounds through a precordial or esophageal stethoscope provides instant and continuous feedback about oxygenation (pulse oximeter), heart rate and rhythm, an impression of the cardiac output (changes in intensity of heart sounds), and the adequacy of ventilation (wheezing, stridor, laryngeal spasm, no air exchange). This information is particularly helpful in diagnosing arrhythmias, hypovolemia, anesthetic overdose, and airway obstruction. It may also be helpful to listen to the sounds of surgery, such as the sudden change in the noise of the suction device with rapid blood loss or the surgeon’s comments regarding technical difficulties with the procedure.

Touch

Intermittently examining a child—especially palpating peripheral pulses and the skin—provides information that may confirm the auditory input about heart rate, cardiac output, blood pressure, perfusion, and temperature.

Airway and Ventilation

The most important consideration in the safe practice of pediatric anesthesia is attention to the adequacy of the airway. Airway obstruction occurs readily because of the unique characteristics of the infant and child airway (see Chapter 12). Thus the anesthesiologist must maintain constant vigilance of the airway to ensure that it remains clear at all times. Airway obstruction may lead to hypoventilation, although the causes of hypoventilation may be central (opioids or inhalation agents) or peripheral (muscle relaxants) in origin. Thus anesthesiologists must always place emphasis and attention on constantly monitoring the adequacy of ventilation, particularly when administering anesthesia via a facemask. This is necessary because the expired carbon dioxide tension may underestimate the true carbon dioxide tension as a result of a poor mask fit with air leaks, in combination with an obstructed airway. The capnogram is usually very accurate during mask anesthesia with a circle breathing circuit. Failure to detect an appropriate end-tidal carbon dioxide tension suggests inadequate ventilation, a mask leak, or reduced pulmonary blood flow, with the result that the child’s condition may deteriorate from lack of an adequate airway or dilution of the anesthetic gas concentrations.

Although it is desirable to optimize ventilation by maintaining an arterial carbon dioxide pressure within the normal range (35 to 45 mm Hg), most healthy infants and children are not harmed by mild to moderate overventilation; however, severe underventilation has more serious implications.

Constantly monitoring the inspired concentration of oxygen, the expired concentration of carbon dioxide, and the oxygen saturation is a valuable adjunct to the senses of sight, hearing, and touch. Failure to ventilate adequately is probably the most important factor in the morbidity and mortality of children undergoing anesthesia.