Critical Analysis of Guidelines for Providing Sedation to Patients Undergoing Gastrointestinal Endoscopy Procedures.

In spite of growing numbers of gastrointestinal endoscopic procedures performed under deep sedation, guidelines are lacking. Hypoxemia and aspiration continue to be the main source of morbidity. Anesthesia providers have tried to address these concerns by modifying their technique and employing newer or improvised devices. In addition, preprocedural evaluation poses many challenges. In many centers, workload pressures determine the time available to perform such an evaluation. A comprehensive history and examination similar to a major surgical procedure is often not possible. As a result, a focused history and examination is essential. This should be followed by an appropriate explanation of risks before obtaining consent. A plan should be in place to manage complications such as aspiration. This paper provides a succinct review of the above aspects. Copyright:

INTRODUCTION

Among all the medical procedures (surgical and nonsurgical) performed in the world, gastrointestinal (GI) endoscopies form the single largest group. In 2017, a total of 51.5 GI endoscopic procedures were performed in the USA alone.[1] Although sedation protocols have varied, propofol remains the most commonly used agent. In addition, the versatility of the modern endoscopist is only limited by the ever-enlarging array of tools at his disposal. Endobariatrics and submucosal resection of a variety of lesions are some such examples.

Unfortunately, advancements in interventions have not kept pace with similar progress in the sedation. Absence of sufficient research and a constant struggle to both own propofol administration privileges as well as to find alternative sedation methods has only added to the confusion. Biased reporting of the research by self-interested groups and societies has further complicated the picture. After failing to seize control over propofol use in GI endoscopic procedures due to the risk of apnea, many other approaches were made to secure propofol administration rights indirectly. First of such effort was an attempt to get fospropofol approved for administration by the gastroenterologists. This prodrug of propofol has similar pharmacodynamic and pharmacokinetic properties. In addition to some unpleasant side effects such as burning sensation in the perineum, apnea and need of airway support were frequent with propofol. As a result, the Food and Drug Administration could not approve its usage by practitioners with insufficient airway management skills, which included gastroenterologists. The second such attempt was approval of Sedasys (R). It should have been clear to the manufacturers that propofol was not the appropriate drug for patient-controlled sedation in procedures where the depth of sedation was similar to general anesthesia.[2] In fact, objective measurements using SedLine (a depth of sedation monitor) have proved that more than 50% of the time, patients undergoing colonoscopy are experiencing either deep general anesthesia or general anesthesia. Inevitably, patients drift into such depths of sedation and endoscopists expect such a degree of sedation from their anesthesia providers. This is even more true in patients undergoing advanced endoscopic procedures. After aggressive marketing and lack of any meaningful marketing results, Johnson and Johnson decided to withdraw the device from the market.[345]

The efforts of GI community have not stopped. The latest effort seems to be focused on finding alternative to propofol in the form of remimazolam.[678]

Instead of trying to establish hegemony by one group, a coordinated effort by both anesthesia and GI endoscopy societies to devise guidelines for safe practice of sedation will go a long way in improving safety of endoscopy practice. Nearly, all guidelines for sedation and anesthesia in GI endoscopy are written by gastroenterologists with no anesthesia provider included in these committees. The evidence used to provide these guidelines comes from the studies conducted by the GI community and published in premier GI endoscopy journals. Even with regard to use of propofol, experience is from endoscopist-guided propofol sedation. The following paragraphs discuss the existing guidelines and their application to patients undergoing endoscopy under sedation. Our own proposed recommendations are incorporated as deemed necessary.

FASTING GUIDELINES

The standard American Society of Anesthesiology (ASA) guidelines are recommended by all the societies with regard to fasting requirements. Nevertheless, majority of the patients are not aware of the 2-h clear fluid rule and continue to present to our endoscopy centers having not consumed any fluids for over 8 h. Those undergoing colonoscopy are particularly vulnerable to hypotension either before or during the procedure. In addition, the incidence of syncope at the time of cannulation could increase. As a result, there needs to be better communication between the health care providers and patients to stress this area and encourage them to drink clear fluids until 2 h before procedure.

Often patients present in endoscopy suite with chewing gum in their mouth. Although our results showed gastric volumes in patients chewing gum were statistically higher, the differences were small difference to have any clinical relevance. As a result, patients who chewed gum inadvertently prior to the procedure should not be denied or delayed administration of sedative and anesthetic medications.[9] Although ASA fasting guidelines are silent on this aspect,[10] the European Society of Anaesthesiology fasting guidelines do not recommend cancellation for chewing gum.[11]

The fasting requirements in patients with achalasia should be dictated by both past experience (of caring that patient) and the disease severity. In those with severe disease, a prolonged fasting, especially to solids and semisolids, is appropriate. In a study of patients, wherein such extended fasting was not implemented, 2 of 22 patients had significant aspiration.[12] One should have a low threshold to intubate these patients.

In spite of all the precautions, occasional patients aspirate both during colonoscopy and upper GI endoscopy. It is important to have a plan to deal with these situations. During upper GI endoscopy, if an anesthesia provider finds unexpected gastric contents and they are liquid, they can be suctioned (without any evidence of aspiration), and the procedure may continue. However, if the contents cannot be easily suctioned, the procedure should be delayed to another day. In a colonoscopy, any evidence of aspiration (such as biliary secretions either in the nose or mouth) should call for stopping of the procedure followed by waking the patient. The patient should be evaluated for clinical signs of aspiration, and a chest roentgenogram obtained if necessary. In the absence of any clinical or radiological signs of aspiration, the patient may be discharged and instructed to report to the emergency room if they develop any signs and symptoms of aspiration such as fever, cough, chest pain and shortness of breath. However, if there are any clinical signs of aspiration, the patient should be admitted for further evaluation and appropriate management.

The following are the predictors for aspiration in patients presenting for GI endoscopy

Achalasia

History of severe gastroesophageal reflux disease

Hiatal hernia

Stricture esophagus

History of esophagectomy

Gastroparesis

Postpyloric obstruction

Zenker's diverticulum.

AIRWAY MANAGEMENT

Availability of an extensive array of airway management options creates the need for guidelines to use them. Hypoxemia and aspiration continue to be major causes of morbidity and mortality.

Administration of supplemental oxygen via nasal cannula continues to be the most common method in patients undergoing colonoscopy. Considering that the anesthesia providers have exclusive control over the airway, this is appropriate. Patients with morbid obesity will benefit from a nasopharyngeal airway which is less stimulating than oropharyngeal airway, in the event of desaturation. I any event, the depth of sedation should be tailored such that patients can protect the airway, if ever there is passive regurgitation. Hypoventilation and carbon dioxide absorption can potentially increase blood CO2 which can render the patients restless. Special sampling devices (such as Smart CapnoLine Plus O2 nasal cannula) are available for sampling the end-tidal gases and should be used.[13]

The airway management of patients presenting for upper GI endoscopy, especially those planned for advanced endoscopic procedures is far more challenging and complicated. However, a vast array of devices is available. In addition, many improvisations with existing devices can cut the costs and be as effective.

High-flow nasal cannula supportive oxygen therapy is useful and should be employed in patients undergoing both routine and advanced upper GI endoscopic procedures. A recent randomized single-blinded study of 1994 outpatients undergoing routine gastroscopy with propofol sedation decreased the incidence of both and severe hypoxia.[14] LMA® Gastro™ Airway (Teleflex Medical, Athlone, Ireland) is another device available to reduce the incidence of hypoxemia in patients undergoing upper GI endoscopy. It allows for esophageal intubation while providing an unobstructed airway and positive pressure lung ventilation with clinically satisfactory seal pressures.[15] However, it requires deeper levels of sedation similar to general anesthesia, and as a result, is useful in selected patients such as those with anticipated difficult airways. Alternatively, endotracheal intubation might be preferable.

Nevertheless, majority of GI endoscopies (both upper and colonoscopy) continue to be safely performed with a standard nasal cannula with supplemental oxygen. If airway difficulties are anticipated, it is safer to employ more definitive airway like an endotracheal tube than intermediate measures.

ENDOTRACHEAL INTUBATION IN PATIENTS UNDERGOING ADVANCED ENDOSCOPIC PROCEDURES

At the hospital of the University of Pennsylvania, we have guidelines to select patients who are unsuitable for deep sedation and as a result, are more appropriately performed under general anesthesia with endotracheal intubation. These could be found in Table 1.

Table 1

Indications for endotracheal intubation in patients presenting for advanced gastrointestinal endoscopy including endoscopic retrograde cholangiopancreatography

Parameter	Grade	Score
BMI	<25	0
	25-35	1
	>35	2
Timing of the procedure	Elective	0
	Urgent/>17:30 weekends/holidays	1
Aspiration risk	NPO/−GERD	0
	+GERD/history aspiration/NG or GI bleed	1
Hemodynamics/cardiac status	Stable	0
	Unstable/sepsis	1
Airway as assessed by Mallampati score	≤2	0
	>3	1

Any score equal or >4, or if the patient is known to have a full stomach or gastric outlet obstruction should warrant strong consideration for securing the airway, irrespective of the score. If uncertain of GI status, a consultation with GI attending is advised. There is no substitution, however, to the thoughtful evaluation and judgment of the anesthesia team. GI=Gastrointestinal, BMI=Body mass index, GERD=Gastroesophageal reflux disease, NG=Nasogastric, NPO=Nil per os

PATIENT SELECTION AND COMMON COMORBIDITIES

With an increase in the number of endoscopy procedures in the USA, especially screening colonoscopy, the need for centers which can perform these procedures has gone up. Clearly, the responsibility to formulate policies and ensuing their compliance is the responsibility of the joint commission in the USA and similar regulatory bodies in other countries. Yet, we consider that the following category of patients should concern the anesthesia providers working in such areas. It is impossible to provide an all-inclusive list. However, an effort is made to address common situations, as they concern endoscopy sedation.

Uncontrolled diabetes

Currently, there are no clear guidelines as to the levels of blood sugar or hemoglobin A1c (HbA1c) that call for cancellation of scheduled procedures.[161718] Hyperglycemia is clearly known to increase the risk of surgical site infections, delayed wound healing, and increases length of hospital stay in patients undergoing surgery. By treating high blood sugar, one can decrease such complications. However, too rigid a control is detrimental. No prospective randomized studies have determined the importance of preoperative control of blood sugar and clinical outcome.

In patients undergoing endoscopy, the implications are different. Complications such as surgical site infections and delayed wound healing are not applicable. Nearly, all the patients are likely to get back to their basal preoperative status within minutes after the endoscopy procedure. As a result, an anesthesia provider could be more liberal both regards to patients' blood sugar levels and historical HbA1c levels. However, levels that are clearly unacceptable (such as a blood sugar of 400% mg) require further evaluation. Testing for ketones bodies and osmolarity for complications such as hyperosmolar hyperglycemic state (high blood sugar with high osmolarity without significant ketoacidosis) or diabetic ketoacidosis may be appropriate.

Patients with fast atrial fibrillation

Preoperative atrial fibrillation can be paroxysmal, persistent, and permanent. From the anesthesia provider's perspective, ventricular rate is far more important than any anticoagulation regimen that chiefly influences the endoscopist in terms of the procedure. Nevertheless, a joint decision is needed, especially if the patient needs either endotracheal intubation or insertion of a nasopharyngeal airway. The ventricular rate influences hemodynamic status. In the presence of anticoagulation and the procedure is clearly needed, insertion of devices such as nasopharyngeal airway should be avoided.

There is no agreement as to the acceptable preoperative heart rate, so also the preferred rate-control intervention. A lenient rate control (<100 bpm) might be acceptable in patients presenting for GI endoscopy.

Frequently, atrial fibrillation is noticed for the first time either during the endoscopic procedure or immediately after the procedure. Majority of the patients presenting in an endoscopy center have risk factors for Afib, both cardiac such as myocardial infarction, cardiomyopathy, hypertension, valvular disease, heart failure, and noncardiac such as diabetes, obesity, alcohol intake (“holiday heart syndrome”), hyperthyroidism, and chronic obstructive pulmonary disease.[1920] It is natural for the patients to blame the anesthesia/anesthesia provider for such complications. If symptomatic, they need appropriate management. If asymptomatic, our approach is to reassure the patient and impress on the likelihood of paroxysmal Afib that might have manifested during the perioperative period. A cardiology consult is essential before the patient is discharged. The patient might be placed on blood thinners pending a complete evaluation.

Uncontrolled hypertension

Similar to the rate control for Afib and optimum glycemic control in patients with diabetes, there is no agreement regarding the acceptable levels of blood pressure control in patients presenting for surgery. Considering the relatively less invasive nature of endoscopic procedures, it might be unacceptable to cancel these patients exclusively for reasons of high blood pressure. Hypertension is not regarded as a risk factor that should lead to deferring or canceling surgery as per the American College of Cardiology/American Heart Association Guidelines on Perioperative Evaluation and Care for Non-Cardiac Surgery,[21] so also the European Society of Cardiology/European Society of Anaesthesiology guidelines.[22] Unless there are associated symptoms suggesting ongoing end-organ-related symptoms such as myocardial ischemia or severe headache, there is no justification for canceling a scheduled endoscopy case purely based on the preprocedure blood pressure reading.[23]

Patients on dialysis

Recently dialyzed patents are more likely to experience hypotension at induction of anesthesia.[2425] These patients are both hypovolemic and have lower oncotic pressure, that leads to further depletion of intravascular volume. In addition, they are likely to be vasodilated. Propofol, the most common agent used in endoscopy causes vasodilation along with intrinsic myocardial depression. In addition to intraoperative hypotension, these patients are prone to immediate postprocedure hypotension as well. Although procedures with minimal physiologic perturbations (like GI endoscopy) are not associated with increased risk for any postoperative complication regardless of the interval between completion of hemodialysis and induction of general anesthesia, in our hospital, elective endoscopic procedures are delayed if the interval between dialysis and procedure is >2 days or <1 day. Recent serum electrolytes should be reviewed. If the trends are on the higher side, preprocedural serum potassium levels should be obtained. A serum potassium is ≥5.5 mEq/L calls for dialysis and rescheduling. In general, parents on dialysis benefit from a reduction sedative, anxiolytic, or analgesic medications. Our guidelines for approaching patients on dialysis are found in Table 2.

Table 2

Guidelines for preoperative evaluation in patients with chronic kidney disease or end-stage renal disease undergoing elective outpatient procedures

Purpose: Reduce perioperative morbidity and mortality and streamline preoperative evaluation to avoid day of procedural delays or cancellation

Scope: Applies to all endoscopists, anesthesia providers, and perioperative nurses

Recommendations: This policy applies to patients with CKD or ESRD who are scheduled for elective endoscopic procedures

Patients with ESRD should receive hemodialysis the day prior to elective endoscopic procedure

Patients who are scheduled for the procedure on Monday, who normally receive dialysis on Saturday, may maintain their normal schedule

Patients who are scheduled for the procedure and who normally receive dialysis M/W/F should have their dialysis schedule changed to receive dialysis on Saturday

Patients undergoing peritoneal dialysis should continue their treatment through the night before the procedure

Patients with ESRD or moderate-to-severe CKD should have a basic metabolic panel as close to the time of the procedure as possible, ideally within 2-4 weeks before the scheduled procedure

A basic metabolic panel or serum potassium may be drawn on the day of the procedure if no recent labs are available or at the discretion of the anesthesia team

Inpatients who are under the care of a nephrologist and are deemed to be stable can have endoscopy on the day of their hemodialysis if anesthesia and endoscopist are in agreement. CKD=Chronic kidney disease, ESRD=End-stage renal disease

History or ongoing drug abuse

As a result of legalization of marijuana use in many states across the USA, patients are more forthcoming about its use. Euphoria, sedation, relaxation, and altered spatial and/or temporal perception are some of the acute marijuana effects that involve the central nervous system. While tachycardia, vasodilation, and orthostasis are part of acute cardiovascular effects, bronchodilation, hyperreactivity, and airway edema are the results of effects on respiratory system. On the positive side, it has anti-nausea properties in short time, although it causes hyperemesis with chronic use. Atherosclerosis, chronic bronchitis, emphysema, and tolerance to CNS acute effects are its chronic side effects. Cannabis withdrawal syndrome is known to occur within a day of cessation for high-dose chronic cannabis users and may take weeks to fully resolve. Irritability, anger, aggression, anxiety, nervousness, insomnia, disturbed dreams, restlessness, depressed mood, anorexia, weight loss, abdominal cramping, tremors, sweating, fevers, chills, and headache are some of the features of withdrawal syndrome.[26]

In terms of anesthesia interaction, there is an increased risk of myocardial infarction within 1 h after use. Both acute and chronic administration leads to significantly higher induction doses of propofol.[27] Airway hyperreactivity is to be expected. Cross tolerance to analgesics is possible with likelihood of heightened pain perception.

Nevertheless, if a patient is found to be using/abusing marijuana, a more detailed history and examination is warranted. However, cancellation is rarely necessary in patients who are solely on marijuana. Attention should be paid to both propofol dose (that may be increased) and postoperative analgesia needs.

Patients with pacemaker/an implantable cardioverter defibrillator

Patients with cardiac implantable electronic devices (CIED) often present in endoscopy centers including for endoscopic electrosurgery. These include snare polypectomy, endoscopic submucosal dissection, and endoscopic retrograde cholangiopancreatography with endoscopic sphincterotomy. Adverse events from endoscopic electrosurgery in patients with CIED is rare suggesting that this procedure is safe.[28] Cases of tachyarrhythmias are reported as a result of electrosurgery. Preprocedural evaluation of the type of device, location of the device, reason for device implantation, and patient dependency are necessary. Bipolar cautery is preferred. Application of a magnet over the pulse generator depends on the type of device. Preprocedural interrogation or inactivation of CIEDs and postprocedural evaluation by an expert are based on the manufacturer's recommendations and in consultation with the electrophysiologist.

Morbid obesity

The implications of morbid obesity for patients undergoing GI endoscopy are slightly different than those presenting for surgery in an operating room. While airway management is likely to be more definitive in patients undergoing surgery, often it is unprotected in patients undergoing GI endoscopy. By appropriate modification of airway, it is possible to reduce the incidence of hypoxemia events to those similar to patients who are of normal weight. We have shown that by using a nasopharyngeal airway connected to a Mapelson breathing system and occasional jet ventilation, upper GI endoscopies including advanced endoscopic procedures can be performed safely.[29] Such a device modification is seen in Figures 1 and 2. However, sedating these patients for a colonoscopy may be more challenging. These patients, especially in the presence of obstructive sleep apnea are prone to hypoxemia and aspiration. Certainly, conscious sedation is safely performed in patients with obstructive sleep apnea without increased intraprocedural complications (hypoxemia and airway maneuvers).[30]

Figure 1

Nasopharyngeal airway – Mapelson breathing system assembly

Figure 2

Nasopharyngeal airway – Mapelson breathing system assembly in use

Preprocedural evaluation and consenting

Based on our extensive experience, we determine that the following should be part of any explanation to patients undergoing GI endoscopy.

“We plan to administer propofol for your procedure with or without fentanyl or any additional drugs as deemed necessary. They will be administered by an experienced anesthesia provider, myself or one of my colleague. You should be asleep in about 30 s and the procedure itself takes about-minutes. We keep a close watch on your oxygen, carbon dioxide, electrocardiogram (EKG), blood pressure, etc., The procedure itself might take minutes. Typically, you will be awake in about 5 min after the procedure and 30 min after that will be ready to go home. Although generally very safe, there are two important risks you need to be aware of. The first is the risk of aspiration, wherein you may inhale your own secretions, blood or vomitus. It can lead to pneumonia and may require hospitalization. The second is hypoxemia, wherein your oxygen levels may drop. Part of my job is to evaluate the likelihood of developing such adverse events and I do not see (or discuss and document if there are any) anything that stands out.” I am happy to answer any questions you may have.

“Here is the consent form, feel free to read it. By signing you are allowing us to administer sedation and do whatever it takes to keep you safe.”

MONITORING

In 2018, American Society of Anesthesiologists, the American Association of Oral and Maxillofacial Surgeons, American College of Radiology, American Dental Association, American Society of Dentist Anesthesiologists, and Society of Interventional Radiology together published practice guidelines to assist the practitioners involved in providing Moderate Procedural Sedation and Analgesia. Continual monitoring of ventilatory function (unless precluded or invalidated by the nature of the patient, procedure, or equipment) with capnography to supplement standard monitoring by observation and pulse oximetry is one of their recommendations.[31] Depending on the choice of airway, it may not be easy to obtain end-tidal gas sample to monitory capnography.[32] Continual monitor blood pressure (e.g., at 5-min intervals) and heart rate during GI endoscopy procedures is standard of care.

In the absence of a reliable end-tidal carbon dioxide monitor, one can use impedance pneumogram [Figure 3] or acoustic respiratory monitor. Impedance pneumogram does not detect breathing against a closed glottis and as a result, patients may desaturate with the tracing displaying ongoing respiratory efforts. This monitor depends on the chest expansion and contraction to detect respiration. The distance between the EKG electrodes widens with each breath that changes the impedance, which gets detected as respiratory effort.

Figure 3

Impedance pneumogram during an esophagogastroduodenoscopy

Acoustic respiration rate monitoring uses a piezoelectric acoustic sensor placed on the neck to detect breath sounds from which respiration rate is derived.[33] It is found to be accurate for assessment of respiration rate and to have similar or better sensitivity and specificity for detection of apnea compared to capnometry and impedance pneumography in the setting of upper GI endoscopy.

Venous air embolism was detected in 2.4% (20 patients) of a total of 843 ERCP procedures that were performed over a 15-month period at the Hospital of the University of Alabama at Birmingham, Birmingham, Alabama. Precordial Doppler ultrasound is likely to detect them and is recommended during high-risk therapeutic procedures.[3435]

SETTING UP THE PROCEDURE ROOM

For the safe administration of deep sedation, we think that the following minimum should be available at all times. In addition, an anesthesia machine should be available, although not in every endoscopy room.

Drugs

Propofol (Drawn up)

Atropine or glycopyrrolate (Drawn up)

Succinylcholine (Drawn up)

Ephedrine (Drawn up)

Phenylephrine (Drawn up)

Epinephrine (Prefilled).

Equipment

Mapelson C breathing system (tested and deployable immediately)

LMA, ET tube

Oral airways

Nasopharyngeal airway

Face mask (opened and attached to breathing system).

The remaining setup is as per the standard for any anesthesia/deep sedation case.

CONCLUSIONS

Evidence-based recommendations are lacking in the area of GI endoscopic sedation. As these procedures are on an increase globally. It is essential that anesthesia providers have some strategies to guide the periprocedural evaluation, sedation administration, monitoring, and postoperative management. We have provided guidelines based on the best available evidence and our own practice.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.