Anesthesia Outside the Operating Room

45 Anesthesia Outside the Operating Room




THE APPROACH TO PROVIDING ANESTHESIA outside the operating room (OR) for children (also known as non–operating room anesthesia [NORA] or off-site anesthesia) varies greatly among organizations and even from one anesthesia provider to another. NORA practice is not as standardized as anesthesia delivered within the OR setting. As such, it is a difficult topic to cover using an evidence-based approach. Although most anesthesiologists would agree (generally) on the optimal methodology for delivering anesthesia to a 2-year-old child for inguinal hernia repair, much more variability (in terms of drugs used, airway management techniques, and general organization) exists in providing anesthesia for a magnetic resonance imaging (MRI) scan. This issue is made even more confusing by the fact that procedures that are performed with sedation in one institution may be accomplished with general anesthesia in another. Furthermore, a procedure that is performed under sedation with an anesthesia provider in one institution may have sedation provided by a specialist other than an anesthesiologist at a different institution.1


The discussion of anesthesia services outside the operating room must also include the recognition that the level of sedation or anesthesia for a given child at any moment during a procedure is often a matter of some conjecture. Almost any procedure that involves pain, or the requirement for absolute movement control in a child, necessitates deep sedation or general anesthesia. The distinction between these two states—defined by the presence or absence of movement in reaction to painful stimuli—is often difficult to determine.2 For anesthesiologists, the difference between these two states is more of semantic interest than practical importance. Anesthesia services are often requested outside the OR when sedation is actually what is required. Finally, anesthesia is often provided outside of the OR for patients with significant comorbidities undergoing routine procedures. Many of these children would be managed with sedation by other specialists were it not for the complexity of the coincident condition(s). Comorbid conditions that require referral to an anesthesiologist vary with institutions but common (generally accepted) examples include:



With these considerations in mind, this chapter focuses on issues specifically related to the delivery of anesthesia and deep sedation outside of the OR provided by anesthesiologists. Issues concerning minimal, moderate, and deep sedation, as well as issues involving care by providers other than anesthesiologists, are covered Chapter 47.



Standards and Guidelines


Anesthesia outside of the OR must meet the same standards as anesthesia given in the OR. Specifically, Medicare’s Conditions for Participation for hospitals are enforced by The Joint Commission (TJC) regardless of location of care. The Conditions for Participation are principles that are articulated to surveyors as instructions in the Interpretive Guidelines published in January, 2011, and available at www.cms.gov/SurveyCertificationgeninfo/dounloads/SCLetter11_10.pdf. These guidelines describe appropriate training, credentialing, and oversight of sedation and anesthesia providers and some of the specific requirements for care documentation. The ASA has developed templates for the required policies that help institutions meet the standards of the new Interpretive Guidelines. These resources can be downloaded from the ASA website at www.asahq.org. With particular reference to NORA, there are several notable templates, as follows:



1. Preanesthesia Evaluation Policy, Form and Note (template)


Within 48 hours immediately before the delivery of the first dose of medication for the purpose of inducing anesthesia, a qualified practitioner must perform a pre-anesthesia evaluation of the patient that includes, at a minimum: a) a review of the medical history, including anesthesia, drug and allergy history, and b) an interview, if possible, given the patient’s condition, and examination of the patient. In addition, the following must be reviewed and updated within 48 hours prior to anesthesia:


a) Notation of the anesthesia risk. b) Identification of potential anesthesia problems. c) Additional pre-anesthesia data or information, if applicable and as required in accordance with standard practice prior to administration of anesthesia (i.e., stress tests). d) Development of the plan for the patient’s anesthesia care, including the type of medications for induction, maintenance and postoperative care and discussion with the patient (parents) of the risks and benefits of the delivery of anesthesia.


2. Intraoperative record policy. Standard data elements and timing must be included in the intraoperative record—just as in the OR.


3. Postanesthesia Evaluation Policy, Note and Form (template)


A postanesthesia note must be completed within 48 hours after surgery. The person completing the evaluation does not have to be the person who delivered the anesthetic. The elements of the postanesthesia note include assessment of the following: a) respiratory function, b) cardiovascular function, c) mental status, d) temperature, e) pain, f) nausea and vomiting, and g) postoperative hydration.


NORA Services must be organized in such a way as to meet the Conditions for Participation (and thus TJC) standards mentioned earlier, just as they are met in the OR environment. Depending on how NORA is organized in a particular institution, this can be challenging. The departments that require anesthesia services must appreciate the need to meet these standards and allow for the infrastructure to meet or exceed them, particularly in the preanesthesia and postanesthesia timeframes.



Off-Site Anesthesia: Structure


Anesthesia services outside of the OR can be organized in various ways. In some institutions these services are organized through an off-site anesthesia unit or sedation unit. These units have the advantage of providing all anesthesia-related care through one location that contains all of the personnel and equipment required for anesthesia. Ideally, these units provide for preanesthesia assessment, induction, procedure location, and a recovery area. Children may be transported to remote locations when equipment (such as MRI) cannot be brought to the sedation unit. The advantages of this organizational scheme are clear. The uniform environment leads to maximum consistency in the equipment and personnel that interact with children and their families and thus adds to safety, efficiency, parent satisfaction, and effectiveness of care. Many experts (along with TJC) advise the formation of specialty teams or microsystems for provision of anesthesia out of the OR. Microsystems are coordinated groups of professionals who deliver a specific service, to achieve the best outcomes by developing reliable, efficient, and responsive systems that have the capability of meeting the individual needs of one child, continually improving care for the next child, and creating a great place to work for all staff. The sedation microsystem should be made up of pediatric anesthesiologists and nursing, technical, and administrative personnel who are familiar with the service and dedicated to this care.3 The microsystem can provide structure and expertise for this care. As members gain expertise and comfort with the off-site environment, their care is consistent and reproducible, leading to less confusion with other services. Such systems of care lead to improved effectiveness (decreasing failed anesthesia and sedation cases) and improve patient and family and staff satisfaction.46


Another option for anesthesia organization outside the OR is the use of standard same-day unit admission and assessment services and postanesthesia care unit recovery capability while providing induction and procedural anesthesia at the site of the procedure (e.g., endoscopy suite or hematology and oncology unit). This organizational paradigm makes use of existing anesthesia ancillary services but often requires patient transport before and after anesthesia.


Finally, anesthesia services outside of the OR may be primarily organized at the site of procedural care. Most typically these services are organized in radiology departments or gastrointestinal procedure suits, where a majority of pediatric sedation and anesthesia takes place outside of the OR. For this organizational setup, the procedure unit itself may be outfitted for admission and preanesthesia assessment. An anesthetizing location can be provided and recovery of children can be accomplished in a space contiguous within the immediate location of the procedural equipment. This kind of organization is most common in children’s hospitals, where high volumes of procedures are performed in a given location such as the MRI scanner.7 In locations such as this, where anesthesia services are required on a daily basis for a multitude of children, the investment in the infrastructure for anesthesia support services makes economic sense in addition to optimizing patient care.



Personnel Requirements


The environment and the demands of providing anesthesia outside of the OR are unique regardless of the specific organization that has been chosen for NORA. To create the kind of functioning sedation microsystem discussed earlier, several common themes lead to optimal safety and effectiveness of off-site anesthesia care:



1. Anesthesia providers should rotate on this service and have a frequency of experience with the environment and ancillary personnel that allow familiarity among the anesthesiologists, nurse anesthetists, respiratory therapists, registered nurses, patient care technicians, biomedical engineers, and child life specialists. This familiarity should be based on a common understanding of the routines and protocols for standard procedures and a common agreement on the goals of the service.


2. Effective and efficient communication among personnel is critical to optimize outcomes. Logically, help from all members of the care team, including the supervising anesthesiologist, should be available within time frames that would allow optimal outcomes for children with critical events—specifically within 3 to 4 minutes. The use of cell phones, Internet phones, or other devices to optimize communication in NORA locations is often helpful.


3. The ancillary personnel in each location must be familiar with the needs and processes of providing anesthesia to children.


4. Equipment and monitoring standards should mimic that of the OR environment (see later discussion). Anesthesia carts and machine preparation and setup should mirror the OR environment as much as possible to maximize the similarity to the most common workspace. It is critical to have a system that allows appropriate restocking and security of anesthesia carts in all of the off-site locations. All off-site carts should include a full range of drugs, intravenous equipment, fluids, and airway equipment such as tracheal tubes, laryngeal mask airways (LMAs), laryngoscopes, oral and nasal airways, masks, and suction equipment in sizes that would fit all possible pediatric age groups.


5. Scheduling off-site anesthesia resources is complex and personally demanding. Timing for some procedures is inexact. In addition, anesthesia time requirements can vary with the child and the associated pathology. Success is enhanced by focusing the task of scheduling NORA procedures with one individual (or a small group) (similar to scheduling cases for the OR) who intimately understands the process involved in anesthesia. This type of organization allows the NORA service to have one focal point for communication between the individuals who perform procedures and the anesthesia service, thus maximizing communication among services and minimizing incorrect assumptions of staffing or timing for procedures.



Specific Environmental Requirements


Equipment (see earlier discussion) and monitoring standards (see later discussion) must meet those of the main OR environment. Regardless of whether the anesthetizing location is inside or outside the OR, the ASA has established minimum standards for equipment, monitors, and conditions of anesthesia delivery. These guidelines may, of course, be exceeded at any time based on the judgment of the involved anesthesia personnel. The ASA specifically requires that remote locations must have two sources of oxygen (O2) (preferably a central source of piped O2 and a backup E cylinder), suction, an anesthesia machine if administering inhalational anesthetics, a scavenging system for waste anesthetic gases, a self-inflating hand resuscitator bag able to deliver 90% O2 and positive-pressure ventilation, standard of care monitors and equipment,7,8 and sufficient electrical outlets, illumination, and space. The ASA Standards for Basic Anesthetic Monitoring include the following:



In addition, it is important to make further adaptations in the non-OR setting. Duplicates of critical equipment, such as laryngoscope handles and blades, should be immediately available. In the MRI unit, it is essential to have MRI-compatible laryngoscope blades and handles, as well as compatible monitoring devices. Each site should be carefully evaluated for important items, such as presence or absence of wall-delivered gases (O2, nitrous oxide [N2O], and air), location of suction equipment, and Ambu bag. Every site must have backup gas supplies. If pipeline O2 is not available, O2 should be drawn from H cylinders (6600 L) rather than the smaller E tanks (659 L).


Many off-site areas do not have wall suction, especially in the MRI environment. MRI-compatible wall suction is not widely available. An alternative method for providing suction in the MRI suite is to mount a suction canister with 30 feet of suction tubing outside the scanner room.9 The suction tubing can then be threaded through a hole in the console wall to access for use in the MRI unit.


Scavenging systems should be carefully evaluated in out of OR locations. When passive scavenging is not possible, active scavenging may be developed by using the wall-source vacuum or wall suction canisters. Ideally, a scavenging system dedicated solely to waste gases should be present.


Electrical circuitry in off-site locations must be upgraded to meet OR standards. Specifically, although the outlets tend to be grounded and hospital grade, plug and outlet incompatibility may be a problem. Adapters and conversion plugs must be available. Although off-site locations tend not to have as great a risk of electrical shock or electrocution to the child as in the OR, it is important to remember that these sites do not have line-isolation monitors. In the event of excessive leakage of current, the anesthesiologist would not be warned. Although the National Electrical Code no longer requires line-isolation monitors in nonflammable anesthetizing locations, it is strongly recommended in areas with multiple power sources. To ensure child and health care personnel safety, biomedical engineers must be attentive to the safe maintenance of all electrical equipment.


It is in the nature of off-site anesthesia that the physical environment and practice patterns are typically that of another medical specialty. It should also be noted that these other specialties practice under standards developed by their own professional organizations that apply to the procedures within their locations reflecting the different procedure goals. The varying specialties involved include (but are not limited to) gastroenterology, dentistry, cardiology, oncology, intensive care, emergency medicine, and radiology.10 Anesthesia providers who work in these environments are well served by familiarizing themselves with the standards for the given specialty area they are working in, as published on the individual websites for the various professional organizations.



Quality Assurance of Anesthesia Services and Outcome in the Off-Site Areas


This chapter reviews issues related to care delivered by members of anesthesiology departments outside of the OR. In this case the quality improvement (QI) and assurance (QA) activities center in the anesthesiology department. Issues relating to sedation services provided by other services are discussed in Chapter 47. Just as is the case in the OR, it is important to have a consistent tracking tool to follow all clinically important complications. Each department can set its own thresholds for review; however, certain incidents logically require inquiry, as follows11:



Many institutions choose to follow other outcomes such as prolonged nausea and vomiting after anesthesia or O2 desaturation events. Regardless of the data that the QI committee chooses to review, the process should include anesthesiologists, nurses, and other technical personnel who are routinely involved in anesthesia care and support. It is particularly important to note that in the case of off-site anesthesia, it is critical to include members of the departments that are served by the service in the quality improvement process. The timing of QI meetings depends on the number and acuity of the non-OR anesthesia provided at a given institution. Review committee meetings should be considered not just an opportunity to evaluate complications but also a forum for exchange of ideas, expertise, and information that can lead to improvements in patient care.



Anesthesia versus Sedation for Non–Operating Room Procedures and Tests in Children


Anesthesiologists can deliver either deep sedation or anesthesia for procedures outside of the OR. The choice of whether to deliver general anesthesia with a secured airway (tracheal tube or LMA) using potent inhalational anesthetics versus deep sedation with facemask O2 and propofol infusion depends on many factors, including the child’s comorbid conditions, the procedure, and the experience and comfort level of the anesthesia provider. Several reviews are available on this topic. For MRI scans, propofol sedation has been suggested as an (overall) safe and effective option in children with airway pathologic conditions or who are premature or very young.12 Similarly, multiple reports have recommended both propofol sedation and general anesthesia with tracheal intubation (GETA) techniques for endoscopies.13,14


No clear evidence exists on which to conclude that one technique is specifically better than another for procedures in which both techniques are effective and safe, such as MRI or endoscopy procedures. Recognizing this fact, it is still important for anesthesiologists to avoid providing GETA in every case (ignoring the possible advantages that deep or moderate sedation could provide in terms of rapidity of emergence and lack of side effects). It is appropriate to carefully evaluate the nature of the sedation/anesthesia provided in the non-OR setting and consider all of the possible implications of a given technique. For instance, how efficient and effective is the care that is provided? How well does the care provided meet the requirements of the procedure in terms of pain and movement control? What are the nature and rapidity of the emergence from sedation or anesthesia and the time that children should remain in the hospital or ambulatory unit between emergence and discharge after a specific procedure with a given technique? Only after careful analysis can guidelines be established for the optimal technique for a given procedure.15


When delivering general anesthesia to children out of the OR, the risk benefit of instrumenting the airway must be carefully evaluated. The LMA is perhaps most useful in the MRI or computed tomography (CT) setting because it maintains spontaneous ventilation, enables the anesthesiologist to monitor ETco2 continuously and provides a clear airway in a child who may otherwise have obstruction with a natural airway. With the LMA in place, the child can be maintained with a relatively low level of anesthesia, allowed to breathe spontaneously, and then rapidly awakened at the conclusion of the scan. After the LMA is placed, anesthesia can be provided with either a continuous infusion of propofol or with a low-dose inhalation agent (sevoflurane 1.5% in 50% N2O/O2). In some circumstances, the LMA may provide a suitable airway in children with bronchopulmonary dysplasia, cystic fibrosis, severe asthma, or active respiratory issues. In children with upper respiratory tract infections, the incidence of mild bronchospasm, laryngospasm, breath holding, and major O2 desaturation (less than 90%) in those whose airway was managed with an LMA was reduced compared with those whose airway was managed with a tracheal tube.16 Similarly, the use of LMAs in ex-preterm infants with bronchopulmonary dysplasia resulted in less coughing and wheezing and greater hemodynamic stability than in those managed with tracheal tubes. In children who underwent a vitrectomy for retinopathy of prematurity, the time to discharge after an LMA was less than that after a tracheal tube.17 LMAs provide more hemodynamic stability during their removal than during tracheal extubation and thus the former may be useful in children with hemodynamic instability.18


Others think any instrumentation of the airway theoretically increases the risk of triggering airway reflexes or regurgitation compared with no airway instrumentation. In healthy children, some clinicians prefer a deep sedation technique, for example, for brain MRI that includes a propofol infusion, an optimally positioned upper airway (with a roll under the cervical spine and the neck extended) and noninvasive monitoring (nasal capnometry supplemented with oximetry, an electrocardiogram, and noninvasive blood pressure).19 Some note that the majority of children do not require an airway during deep sedation for medical procedures. However, in some (e.g., those with excess secretions or upper airway obstruction during the sedation), the following algorithm of airway intervention may be followed to relieve the obstruction: reposition the head and shoulders, insert an oral airway, insert a nasal airway, place an LMA, and finally, if the LMA fails to clear the airway, place a tracheal tube.



Logistics of Managing Acute Emergencies and Cardiopulmonary Arrest Outside the Operating Room


Although the actual management of a cardiopulmonary arrest should not vary between the OR setting and the non-OR setting, the logistics of performing a resuscitation may be challenged by unanticipated factors, such as personnel who may not be familiar with code situations, an environment that makes performing a resuscitation difficult, or equipment that may be unsafe if used in the particular location (e.g., the MRI environment). It is important that all personnel in the off-site location be familiar with the location and operation of the code cart. The anesthesia cart and the code cart in the off-site location should be stocked in the same precise configuration as all others throughout the hospital and ORs. Standardizing the code carts throughout the hospital ensures that all ancillary personnel can be helpful in locating critical items. If the code cart is kept locked, the key or access code must be readily accessible and in a location that is known to all essential personnel. A hard board on which chest compressions may be performed should also be readily available. Each off-site location should have an identified and rehearsed routine for announcing a code situation and summoning aid. The use of human patient simulation can be very helpful in testing the team response to critical events. Simulators can be used in place in off-site locations to replicate critical events and evaluate the ability of the care team and backup systems to resuscitate a patient. Blike and colleagues used exactly this methodology to document significant variation in the ability of rescuers to resuscitate children from sedation or anesthesia critical events in locations outside the OR.20


Of all the non-OR environments in which anesthesiologists are asked to provide care, the MRI scanner poses a unique challenge for cardiopulmonary resuscitation. The MRI environment is divided up into four zones that correlate with the intensity of the magnetic field and the risk to children and health care providers. These zones are delineated in Table 45-1.


TABLE 45-1 Descriptions of the American College of Radiology’s Four Zones in the Magnetic Resonance Imaging Suite























ACR Zones Occupants Hazards
Zone I General public Negligible
Zone II Unscreened MRI patients Immediately outside area of hazard
Zone III Screened MRI patients and personnel Potential biostimulation interference, access to magnet room
Zone IV Screened MRI patients under constant direct supervision of trained MRI personnel Biostimulation interference, radiofrequency heating, missile effect, cryogens

ACR, American College of Radiology; MRI, magnetic resonance imaging.


From the Joint Commission International Center for Patient Safety. Available at: www.acr.org/~/media/ACR/Documents/PDF/QualitySafety/MR%20Safety/SafeMR07.pdf.


In 2009 the ASA published a report titled Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging: A Report by the American Society of Anesthesiologists Task Force on Anesthetic Care for Magnetic Resonance Imaging.21 This document advises that in the case of a medical emergency in a patient within the scanner, the anesthesia providers should (1) initiate cardiopulmonary resuscitation while immediately removing the patient from zone IV, (2) call for help, and (3) transport the patient to a previously designated safe location in proximity to the MRI suite. This designated location should contain a defibrillator, vital signs monitors, and a code cart with all resuscitation drugs, airway equipment, O2, and suction. Other acute emergencies that are unique to the MRI environment include a “quench” or a fire in the scanner. Quenching occurs when the liquid that cools the magnet boils off rapidly and results in helium escaping from the cryogen bath. The magnetic field of the magnet is rapidly decreased because the coils in the magnet cease to be superconducting and become resistive. In addition to performing the institution’s protocol in reaction to either of these events, the ASA consultants involved in writing the advisory agree that in the event of a quench, (1) the child should be removed from zone IV immediately and (2) O2 should be administered immediately; (3) because of the powerful magnetic field that can exist after a quench or a fire, emergency response personnel should be restricted from entering zone IV.



Difficult Airway Management in the Non–Operating Room (Off-Site) Environment


Two potential difficult airway scenarios may occur in non-OR locations: the child with a known difficult airway and the child with an unrecognized difficult airway. Extensive literature addresses these scenarios, but logic would dictate that children who were preidentified as having potentially difficult airways should have their airways secured in the controlled environment of the OR. Regardless of an anesthesiologist’s comfort level and familiarity with the intended off-site environment, the critical backup personnel and the full array of airway equipment are not always available in remote locations. It is important to note that a fiberoptic bronchoscope and light source are not MRI compatible. It is easier to perform a fiberoptic intubation or to have the fiberoptic equipment readily available in an OR. In this environment, both the nursing and anesthesia support staff (technicians, other anesthesiologists, and otolaryngologists) are readily available and prepared to provide assistance. After intubation, the child may be safely transported to the off-site location for subsequent care.


The more difficult scenario is that of the unrecognized difficult airway22; this scenario may best be handled by establishing a local management protocol that can be activated when the situation arises. Each institution has peculiar equipment, space, and personnel resources. NORA leaders should establish a local protocol for management of the unanticipated difficult airway in an off-site location. In some cases this might involve bringing advanced airway management equipment to the location in a rapid, organized manner. In other cases the best option would include “temporizing” management with alternative airway devices and transporting the child to a location where a definitive airway can be placed in a controlled manner. For this reason, it is important to have alternative airway devices such as LMAs stocked in all anesthesia carts that are designated for off-site locations. In the event that the lungs cannot be ventilated or the trachea intubated, the LMA can provide a lifesaving temporary airway until more definitive action can be taken.23,24



Specific Locations for Non–Operating Room Anesthesia



Computed Tomography


CT involves ionizing radiation and can provide a good modality for differentiating between high-density (calcium, iron, bone, contrast-enhanced vascular and cerebrospinal fluid [CSF] spaces) and low-density (O2, nitrogen, carbon in air, fat, CSF, muscle, white matter, gray matter, and water-containing lesions) structures. Because the scan time for current devices is brief, with actual imaging time ranging from 5 to 50 seconds per sequence, many children are able to tolerate CT without sedation or anesthesia. In cases in which anesthesia is required, it is often for those who have a fragile or unstable respiratory or cardiovascular status. Anesthesia or sedation is often required for children who are unable to cooperate (cognitively impaired children and those younger than 2 to 3 years of age) or require CT emergently. Emergent indications for CT include head trauma, unstable respiratory status in need of a pulmonary diagnosis, unexplained changes in mental status, or neoplasm workup in severely debilitated children. Anesthesia management is also necessary with a potentially unstable airway (peritonsillar abscess, anterior mediastinal mass, craniofacial anomaly, tracheoesophageal fistula, uncontrolled vomiting, or gastroesophageal reflux), or the need for breath holding during acquisition of images (three-dimensional dynamic airway studies) (Figs. 45-1 and 45-2). Some CT units are particularly concerned about children moving when contrast is injected (because of dose restrictions the contrast injection cannot be repeated) and therefore request anesthesia services for any child they cannot confidently predict will stay motionless for the study.




Children with Down syndrome present a particular area of interest for the anesthesiologist working with the CT scanner. These children pose a unique risk for atlantoaxial instability and may require a head or neck CT to evaluate cervical and temporomandibular anatomy, recurrent sinusitis, or choanal atresia. The incidence of atlantoaxial instability varies from 12% to 32%.25 Many children with Down syndrome require cervical spine radiographs before entering grade school or participating in the Special Olympics. Usually, the parents know the outcome of these tests and can relay the results of cervical spine radiographs. These studies alone do not indicate to the practitioner whether the child is at risk of dislocation.23 Rather, it is the presence of neurologic signs or symptoms that would herald a spine that is “at risk”: abnormal wide-based gait, incontinence, increased clumsiness, fatigue with ambulation, complaints of numbness, tingling in an extremity, weakness of an extremity, or a new preference for sitting games. In infants, these clinical signs may be difficult to assess. In younger children, developmental milestones (e.g., crawling, sitting up, reaching for objects) should be evaluated. Physical signs may include clonus, hyperreflexia, quadriparesis, neurogenic bladder, hemiparesis, ataxia, and sensory loss. Children with atlantoaxial instability on a radiograph are at less risk for dislocation if they do not exhibit any signs or symptoms of instability. Children who are capable of following commands are asked to perform full neck flexion and extension maneuvers to determine whether pain, sensory, or motor manifestations of cord compression develop.


Perhaps the most controversial issue facing anesthesiologists with regard to CT scans is the issue of oral contrast for CT. Because children lack abundant retroperitoneal fat, they do not have the natural contrast needed to elucidate abdominal images. For this reason, children may be required to ingest (orally or via nasogastric tube) diatrizoic acid (Gastrografin) to opacify the stomach and bowel. Oral contrast is useful in the identification of an intraabdominal abscess, mass, fluid collection, bowel injury, pancreatic injury, or other traumatic injury. The oral contrast comes as Gastrografin 3% and may be diluted to a 1.5% to 2.5% strength concentration. Gastrografin 3% is the full-strength concentration; in this undiluted form, Gastrografin is hypertonic (2200 mOsm/L). At this concentration, it can cause pulmonary edema, pneumonitis, osmotic effusions, and death if aspirated. Fortunately, when Gastrografin is administered to children for CT it is diluted to 1.5% to 2.5% strength, which is thought to be much less dangerous if aspirated. The volume of oral contrast that is administered can be quite large. Neonates typically receive 60 to 90 mL. Infants between 1 month and 1 year of age may receive up to 240 mL. Children between the ages of 1 and 5 years receive between 240 to 360 mL of contrast medium. Risk is introduced when these children require anesthesia within an optimal window after ingestion (usually 30 minutes to 1 hour after receiving the contrast agent) to enhance visualization. By most fasting guidelines (nil per os [NPO]), Gastrografin consumption within 1 to 2 hours of an anesthetic or sedation does not fall within the usual NPO guidelines. Yet, the scan must be completed while the Gastrografin is present in the gastrointestinal tract. Despite the large volume of Gastrografin that may be ingested, there does not appear to be a significant aspiration risk in this population, and many anesthesiologists do not secure the airway with a tracheal tube (Fig. 45-3). A review of the pediatric and adult literature confirms that over the last 35 years only a few case reports have been published of aspiration syndrome attributed to Gastrografin, all in extremely high-risk patients.2426 Several investigators have evaluated this issue from different perspectives. In one study, a cohort of 50 patients who received oral contrast after blunt abdominal trauma were evaluated for radiologic evidence of aspiration pneumonia or clinical complications of aspiration.27 Some of the patients received general anesthesia, and some were neurologically impaired (including several with increased intracranial pressure). In this very high-risk group, only one patient had a question of aspiration on a chest radiograph after the CT scan, and that patient did not develop pulmonary symptoms. Another study evaluated the volume of gastric contents of 365 patients undergoing deep sedation or general anesthesia for abdominal CT scans.25 Gastric contents exceeded 0.4 mL/kg in 49% of those who received gastric contrast. Two cases of vomiting were recorded. None of the patients in the study developed clinical evidence of aspiration. When dilute Gastrografin is used, the risks associated with pulmonary aspiration appear to be small, even in children who are moderately to deeply sedated.28

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May 25, 2016 | Posted by in ANESTHESIA | Comments Off on Anesthesia Outside the Operating Room
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