Quality and Safety Corner

Prescreening of Patients for Pediatric Procedural Sedation

Cheri LandersBy Jocelyn Grunwell, MD and Pradip P. Kamat, MD

What is Pre-screening?
Pre-screening can be defined as a triage system for thoroughly evaluating pediatric patients.  Pre-screening helps to determine which children are appropriate candidates for procedural sedation provided by a pediatrician who subspecializes in intensive care, emergency care, or hospital medicine.  After careful assessment, there are some children who will require that an anesthesiologist manage their airway during sedation.

Why is Pre-screening Needed?
The demand for pediatric procedural sedation is increasing. Given the shortage of pediatric anesthesiologists, pediatricians from critical care, emergency care and hospitalist subspecialities must fill the void. While these physicians can recognize and manage airway issues that may arise during deep sedation, they do not have the same training or tools for airway management that an anesthesiologist has in the operating room. For example, the anesthesiologist can quickly intubate the trachea of a patient due to deterioration from airway obstruction; however, the same resources are not necessarily readily available during routine pediatric sedation outside the operating room.  Therefore, patient selection is a critical element in the provision of safe procedural sedation outside the operating room.

How is Pre-screening Accomplished?
Sedation pre-screening focuses on identifying potential risk factors that lead to difficulty with airway management and hemodynamics during procedural sedation.  Anticipating problems before they arise is a hallmark of providing safe care during procedural sedation.  In order to select the optimal sedation candidate, the sedation provider must complete an evaluation that includes the patient’s clinical history, medications, and diagnoses that require the scheduled imaging or procedure under sedation. The evaluation must include a physical exam with special attention given to the airway, lungs, heart and neurologic status. Most institutions providing pediatric procedural sedation have compiled a list of “red flags” from experience, and there are conditions that put patients at high risk for complications during sedation. At our institution, once an order is placed for a patient under seven years of age to have an imaging study or a procedure, a sedation nurse screens the patient for the high-risk conditions shown in Table 1. If a patient is noted to have any of the high-risk characteristics, or if there is uncertainty about a patient’s ability to safely undergo procedural sedation, the nurse refers the case to a sedation doctor who may discuss the suitability of sedation with a cardiologist, pulmonologist or neurologist.

Table 1

Following the initial screening by the sedation nurse, an ASA class is assigned to further define the patient’s current disease state. The ASA classification system is shown in Table 2.  ASA class I and II patients are suitable for most sedation providers, and some high-volume programs may be able to accommodate ASA class III patients; however, performing sedation on ASA class III patients requires providers with appropriate advanced training in critical and emergency care with appropriate airway handling skills. Patients who are designated as ASA IV and above are best cared for by an anesthesiologist.

Table 2

Once a patient is determined by pre-screening to be a candidate for procedural sedation, a sedation nurse will call the parents and give detailed instructions including nil-by-mouth (NPO) guidelines and medication use prior to the scheduled sedation date.

Our sedation service uses the AAP NPO guidelines. Although the NPO status is controversial in emergent scenarios, physicians providing sedation must weigh the risks and benefits before sedating a patient who is not NPO, as these patients are at high risk for aspiration.  On the day of the sedation, the sedation provider performs a history and a physical exam. Table 3 provides a useful mnemonic to remember the most important elements of the patient’s history.

Table 3

A physical exam focusing on airway, respiratory, cardiac and neurologic systems is performed. Attention should be paid to baseline vital signs.  An airway assessment should include careful examination of the head, neck, and nose, and any dysmorphic features such as mid-face hypoplasia, receding mandible, short neck, large tongue, and small mouth opening should be noted. These factors can indicate airway difficulty with bag mask ventilation or intubation. The Mallampati classification, while neither specific nor sensitive, relates the tongue size to the pharyngeal size, and a consultation with an anesthesiologist is strongly suggested for patients with a Mallampati class IV.

Table 4

In any laboratory investigations, such as a complete blood count (required for leukemia patients undergoing a lumbar puncture or bone marrow aspirate) or chemistry panel (required for patients needing IV contrast), the results should be available prior to sedation for a procedure. If an EKG, an echocardiogram, or a sleep study is required, then sedation should be postponed until the results from these studies are obtained.  Discussion with the radiologist or the radiology technician will help with appropriate advance planning about the use of intravenous contrast or radioisotope that needs to be injected prior to sedation. Injection of contrast or an isotope should only occur AFTER the patient is deemed to be a sedation candidate. This practice prevents parental frustration, inefficient use of the radiology and sedation team’s time, and the waste of expensive study reagents and time lost on the MRI scanner.

What Are Some Challenges Faced by Sedation Teams?
Sometimes, despite pre-screening, a patient is determined not to be a suitable candidate for procedural sedation following completion of the history and physical exam by the sedating physician. Pressure is often placed on the sedation physician to provide sedation for high-risk patients by the patient’s parents and from the referring doctors who want the radiology imaging or procedure performed.  Parents have often arranged an absence from work and may have travelled long distances to bring their child to the hospital for procedural sedation.  The anesthesiologist may be too busy to accommodate the patient on the same day. 

What Are Some Risk Factors that Require Special Consideration?

Obesity:  Children with body mass index (BMI) > 95% are at a higher risk for complications during sedation than children with a BMI in the recommended range.  Obese children can obstruct their airway, be difficult to BMV, have decreased lung compliance, and be difficult to intubate. Furthermore, they may have other complications associated with obesity, such as hypertension, diabetes and cardiac issues. What is unknown is whether a BMI threshold exists for referring obese patients to an anesthesiologist for sedation.

Snoring and Obstructive Sleep Apnea (OSA): Whether a patient snores is a frequent pre-screening question used to determine a patient’s suitability for sedation.  This is an imperfect screening question as not all patients who snore carry the diagnosis of OSA. At our institution, patients with a sleep study proven diagnosis of OSA are referred to an anesthesiologist due to the high risk of airway obstruction and complications with procedural sedation.

Upper Respiratory Tract Infection (URI)/Allergic Rhinitis: URIs due to viruses are very common in infants and children during the winter months, and symptoms from allergic rhinitis tend to flare during the spring and fall months.  Studies have shown increased odds of failing sedation when a patient has an URI. The risk of complications during sedation is increased when a patient with an URI or allergic rhinitis is exposed to parental smoking, especially when patient is given an inhaled anesthetic. At our institution, if a patient presents with symptoms of an URI, cough, or purulent rhinitis, then the patient is rescheduled for the imaging study or procedure with sedation three to four weeks from the onset of symptoms.

Metabolic Disorders and Inborn Errors of Metabolism: Medications such as propofol may not be appropriate for procedural sedation in patient’s with mitochondrial diseases. Furthermore many patients with genetic syndromes are on special formulas and nocturnal continuous feeding. These patients may not be the best candidates for “run of the mill” NPO instructions and may need to be admitted the day before sedation to be started on special customized intravenous fluids including lipids.  Finally, there is concern about the neurotoxicity of certain anesthetic/sedation agents in children. Animal studies have shown that Ketamine can cause neuronal apoptosis.

Summary
Sedation teams cannot sedate all patients requesting sedation.  Pre-screening helps to refer patients at high risk for complications of procedural sedation to an anesthesiologist.  Appropriate pre-screening not only aids in the selection of optimal sedation candidates, but also increases the likelihood of completing the radiologic imaging study or procedure safely and successfully. The training of the schedulers and sedation nurses in proper pre-screening methods can increase the efficiency of a sedation service by reducing errors in pre-screening that miss high-risk patients who should have been referred to an anesthesiologist and result in last-minute cancellations.

References:

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