Patient preparation and principles of sedation in gastrointestinal endoscopy

Published on 13/02/2015 by admin

Filed under Gastroenterology and Hepatology

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1847 times

28 Patient preparation and principles of sedation in gastrointestinal endoscopy

Case

A 67-year-old male with a past history of mitral valve stenosis and insulin-dependent diabetes mellitis with moderate renal impairment requests his primary care physician to organise colon cancer screening. An open-access colonoscopy is arranged.

The patient presents for the procedure with moderate dehydration following preparation with three sachets of sodium phosphate solution. The patient is noted to be hypoglycaemic, having taken his usual dose of insulin that morning. He requests antibiotic prophylaxis for the procedure (as he has been told always to request this prior to invasive procedures). He is angry when this is refused and becomes more agitated when the consultant acquiesces and asks the nurse to prepare 1 g of ampicillin.

He is sedated with midazolam and fentanyl. During the procedure he receives oxygen supplementation but no capnography or pulse oximetry. He is uncomfortable during the procedure and complains that he is not ‘asleep’. He is given three further doses of midazolam, initially becoming more agitated, but eventually settling. After several minutes the nurse notes that he does not appear to be breathing. The medical emergency team is called but takes 5 minutes to respond. He is given flumazenil and becomes extremely agitated and tremulous. It is then noted that he takes valium for anxiety and temazepam at night.

This patient, although an extreme example, illustrates some of issues of appropriate preparation for an endoscopic procedure. The patient was given inappropriate bowel preparation, no instruction on the management of his insulin and no information about what to expect during the procedure. The proceduralist was correct not to recommend antibiotics, but his reasoning should have been explained and discussed rather than simply agreeing with the request and ordering penicillin without discussion. He had not had a chance to adequately discuss his history with the proceduralist, who did not know that he was allergic to penicillin, nor that he was on regular benzodiazepines. He was subsequently over-sedated for the procedure and had inadequate non-invasive monitoring.

‘Open access’ endoscopic services are relatively common, but if this type of service is to utilised it is paramount that the proceduralist have effective measures in place in order to obtain appropriate informed consent and identify patients for whom special issues regarding preparation are required. In short, the patient must understand the procedure and the proceduralist must understand the patient.

Introduction

Gastrointestinal endoscopy is an important tool in the diagnosis and treatment of many diseases. A broad range of endoscopic procedures are now commonly performed in addition to conventional diagnostic gastroscopy and colonoscopy, including endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasound, and insertion of percutaneous endoscopic gastrostomy. In addition, gastrointestinal haemorrhage is often managed endoscopically, and colonic or upper gastrointestinal tract polyps can be resected via endoscopic mucosal resection. The volume of endoscopic procedures performed demands that these procedures are as safe as possible. The American Society of Gastrointestinal Endoscopy has published excellent guidelines covering all aspects of patient preparation and sedation.

This chapter deals with several of the most important aspects of providing a safe endoscopic practice: preprocedure patient assessment, management of anticoagulation, antibiotic prophylaxis and intraprocedural sedation.

Preparing Patients for Endoscopy

Informed consent

Law suits against gastroenterologists are not uncommon, and in many Western countries most endoscopists can expect to be sued during their career. Endoscopic procedures are inherently dangerous and complications will occur. However, a poor clinical outcome of itself does not equate to negligence or malpractice. Many actions could be prevented (or at least effective defended) by the gastroenterologist taking care to obtain informed consent. Although this does not defend against poor medical practice, it ensures that the patient is responsible for key management decisions.

Informed consent is a process, not a signed piece of paper. It requires that the patient understands the procedure, likely outcomes, potential complications and alternative management strategies. Provision of information to patients prior to the procedure is an important step, but never supplants the opportunity to discuss the procedure with the proceduralist. The type of sedation planned should also be discussed, including the risks of sedation. With regard to conscious sedation many patients will complain about awareness during the procedure unless forewarned that the aim is comfort and not unconsciousness. The patient’s expectations should be explored, and the possibility mentioned that the procedure may not be successful or solve the patient’s problem (missed lesions at colonoscopy are a relatively frequent cause of litigation).

Bowel preparation for colonoscopy

The quality of the bowel preparation prior to colonoscopy is critical in order to provide good views during endoscopy, and thus minimise the risk of missed lesions due to poor endoscopic views. The importance of this is illustrated by the fact that adequate bowel preparation is often included as a quality indicator in colonoscopy. The preparation is often regarded as unpleasant, and many patients are more concerned about the preparation than the actual procedure. As such, detailed explanation both verbally and written is important in order for this to be performed correctly and safely. If the bowel preparation is inadequate, the procedure may need to be deferred. It is important for patients to be informed that they should drink clear fluids only on the day prior to the procedure in addition to the bowel preparation in order to prevent dehydration, and to improve the effectiveness of the bowel cleansing. In addition, mobilising during the preparation may improve the effectiveness of the preparation, especially in the elderly.

The two main constituents widely used for bowel preparation are non-absorbed, isotonic solutions such as polyethylene glycol and low volume hypertonic solutions such as sodium phosphate and sodium picosulfate. Polyethylene glycol is an osmotic laxative that contains electrolytes in order to balance electrolyte shifts; as such it can be regarded as isoosmotic. It is mixed in a large quantity of water; for example the patient may need to drink a total of 3–4 L of fluid. This is usually taken the day prior to the procedure, but if a morning procedure it should be given as a ‘split’ preparation, where part of the preparation is given on the morning of the procedure. This may improve the effectiveness and tolerability of the preparation; however, it needs to be taken at least 4 hours prior to the procedure in order for the stomach to be empty, to reduce the risk of gastric aspiration.

Sodium phosphate (NaP)-based solutions work via a hyperosmotic mode of action, and can be given in much smaller volumes of water. As such, NaP is often tolerated better by patients. It can be combined with a polyethylene glycol-based regimen in order to improve tolerability and reduce volume. The NaP-based solutions do have some risks, including sudden fluid shifts within the body and precipitating acute phosphate nephropathy. Therefore, it should be avoided in the elderly and in patients with congestive heart failure or renal failure. In addition, caution is required if patients have an increased risk of electrolyte disturbance such as those with cirrhosis, small or large bowel dysmotility or other preexisting electrolyte imbalances.

The sodium picosulfate (Picoprep) preparation has no risk of phosphate nephropathy. Patients should be encouraged to drink fluids liberally during hypertonic-based bowel preparation. Patients with known or suspected inflammatory bowel disease may not be suitable for NaP-based preparations, due to an increased risk of causing preparation-related colonic inflammation compared to polyethylene glycol-based solutions.

Endoscopic retrograde cholangiopancreatography

Patients undergoing ERCP will be exposed to ionising radiation. Therefore women of childbearing age should have pelvic shielding during the procedure. If there is any possibility of pregnancy a serum or urinary β-human chorionic gonadotropin should be checked. Contrast medium in the bowel lumen can obstruct views of the biliary system, so patients who have recently had a CT scan with contrast or a barium study should have a plain abdominal x-ray to ensure the biliary system is not obscured. As iodinated contrast is used to inject into the biliary system, a history of iodine allergy or hyperthyroidism should be elicited, though history of a contrast allergy is not an absolute contraindication as the risk of an allergic reaction during ERCP is extremely low. Patients with biliary obstruction should receive prophylactic antibiotics prior to the procedure. Due to the risk of bleeding with sphincterotomy of the ampulla of Vater, elective patients on clopidogrel should ideally withhold this medication for 7–10 days if feasible. The risk is lower with aspirin (all therapeutic endoscopy can be performed on aspirin). Discussion with the patient’s cardiologist is prudent if there is uncertainty whether it is safe to withhold these medications. Coagulopathy should be reversed if present; patients on warfarin may need to change to low-molecular-weight heparin prior to the procedure depending upon the indication. The decision when to reinstitute anticoagulant therapy following therapeutic procedures such as ERCP and colonic polypectomy is a difficult one and should be individualised in consultation with the patient’s cardiologist.

Antibiotic prophylaxis

Advice regarding antibiotic prophylaxis prior to endoscopic procedures was significantly updated in American Society for Gastrointestinal Endoscopy guidelines (2008) based on the recognition from the American Heart Association that bacterial endocarditis from endoscopic procedures was exceedingly rare. For the majority of patients undergoing endoscopic procedures, including those with prosthetic heart valves or congenital cardiac abnormalities, antibiotic prophylaxis to prevent bacterial seeding was no longer recommended. There are however, certain situations in which the risk of infective complications (which may be local rather than systemic) is increased and antibiotics are warranted; these are listed in Box 28.1.

Box 28.1 Antibiotic prophylaxis for endoscopy

All patients prior to insertion of percutaneous endoscopic gastrostomy

Endoscopic ultrasound:

• guided puncture of cystic lesions; or
• pseudocyst drainage.

ERCP:

• bile duct obstruction in absence of cholangitis, only if incomplete drainage is anticipated (e.g. hilar stricture, primary sclerosing cholangitis).1

All patients with cirrhosis with acute GI bleeding (intravenous ceftriaxone from admission)

All patients with cholangitis require antibiotics; patients with biliary obstruction without cholangitis undergoing ERCP require antibiotics only if incomplete drainage is anticipated. Similarly, patients with diffuse sclerosing cholangitis should receive periprocedural antibiotics. There is insufficient evidence to recommend antibiotic prophylaxis for endoscopic ultrasound-guided aspiration of solid lesions, though it is warranted for cystic lesions or pseudocyst drainage.

Disease-specific issues

Patients can take their normal medications several hours prior to the procedure with a sip of water. The management of patients taking antiplatelet agents or anticoagulants is a complex issue, and should be in accordance with published guidelines. These guidelines take into account whether the procedure is elective or an emergency procedure, the indication for the antiplatelet agent or anticoagulant, and the bleeding risk related to the procedure. A suggested algorithm for management of patients requiring anticoagulation is outlined in Figure 28.1.

image

Figure 28.1 Guidelines for the management of patients on warfarin or clopidogrel undergoing endoscopic procedures. AF = atrial fibrillation; EMR = endoscopic mucosal resection; ERCP = endoscopic retrograde cholangiopancreatography; EUS = endoscopic ultrasound; FNA = fine needle aspiration; INR = international normalised ratio; LMWH = low-molecular-weight heparin; PEG = percutaneous endoscopic gastroenterostomy; VTE = venous thromboembolism.

From Veitch AM, Baglin TP, Gershlick AH, et al. Guidelines for the management of anticoagulant and antiplatelet therapy in patients undergoing endoscopic procedures. Gut 2008; 57:1322–1329.

The management of patients with diabetes mellitus will depend upon whether they have type 1 or type 2 diabetes, and on whether they are diet-controlled or on diabetic medications or insulin. Patients with type 2 diabetes are more easily managed as they can generally withhold their medications or insulin on the morning of the procedure. If undertaking bowel preparation on the previous day, similar withholding or reduction in dosage is appropriate. For type 1 diabetes the management is more complicated as some maintenance insulin is required in order to avoid the risk of precipitating ketoacidosis. Involvement of the patient’s diabetic specialist may be useful, and in some situations admission to hospital early on the day of the procedure or even the night before the procedure for an insulin/dextrose infusion may be appropriate. Diabetic patients should be first on elective morning endoscopy lists in order to minimise fasting and disruption of glycaemic control.

Principles of Anaesthesia for Endoscopy

Introduction

The anaesthetic management of a patient undergoing an endoscopic procedure should take into account a number of factors including the type of procedure, the patient characteristics and their wishes, and the expertise and preferences of the proceduralist and staff members.

Patients may have comorbidities that increase the risk of sedation, especially in the older age group. Gastroenterologists need to be comfortable assessing patients for their anaesthetic requirements prior to a procedure in addition to managing their primary gastroenterological problem. Depending upon the facility in which procedures are performed, the anaesthetic (which may also be referred to as ‘sedation’ with the exception of general anaesthesia) may be given by the proceduralist with the assistance of nursing staff, a nurse anaesthetist or by a dedicated anaesthetist. There is wide variation between different countries regarding sedation management; it is a reflection of cultural expectations, health insurance structure and workforce training (e.g. nurse anaesthetists are common in some countries but not others).

The aim of anaesthesia is to provide a comfortable experience for the patient during the procedure, and to keep the patient still to enable the procedure to be performed. Sedation can be divided into different categories according to the depth of sedation. The American Society of Anaesthesiologists provides the following categorisation (see Table 28.1). The term ‘moderate sedation’ is being increasingly used instead of the potentially confusing term ‘conscious sedation’. Note that patients can move between different sedation states quickly, and proceduralists targeting a level of sedation should be competent at managing patients who enter the next deeper level of sedation. Assessment of the depth of sedation can be difficult as there is no widely accepted objective measure of the depth of sedation. A study of 80 patients sedated for endoscopy with the view to moderate sedation with midazolam and meperidine (pethidine) showed that 68% of patients entered a period of deep sedation at some point during their procedure.

Table 28.1 Clinical states of sedation (American Society of Anaesthesiologists)

Sedation level Characteristics
Minimal sedation Normal response to verbal stimulation.
Moderate sedation Purposeful response to verbal or tactile stimulation. Spontaneous ventilation is adequate and no airway intervention is required.
Deep sedation Purposeful response only after repeated or painful stimulation. Spontaneous ventilation may be inadequate, and airway intervention may be required.
General anaesthesia Unrousable, even with painful stimuli. Airway intervention is often required and spontaneous breathing is usually inadequate. Cardiovascular compromise may occur.

Patient assessment

The assessment of a patient initially comprises a thorough history of comorbidities, exercise tolerance and medications (including over-the-counter remedies and allergies). History of tobacco, alcohol and illicit drugs should be elicited, as should difficulties related to previous anaesthetics. A focused cardiorespiratory examination should be performed for all patients, especially to detect occult valvular disease. Of particular interest is the use of potent thienopyridine antiplatelet agents such as clopidogrel and prasugrel, and anticoagulants such as warfarin.

A useful guide for assessing anaesthetic risk has been developed by the American Society for Anaesthesiology (Table 28.2). Patients with an ASA status greater than III should be managed by an anaesthetist.

Table 28.2 American Society of Anaesthesiologists (ASA) classification of anaesthetic risk

Class  
I The patient is normal and healthy
II Mild systemic disease that does not limit activity (e.g. controlled hypertension)
III Moderate or severe systemic disease that does not limit activity (e.g. stable angina, diabetes mellitus with systemic sequelae)
IV Severe systemic disease that is a ‘constant threat to life’ (e.g. end-stage renal failure, severe cardiac failure)
V Patient is morbid and at substantial risk of death within 24 hours (whether the procedure is performed or not)
E Emergency status: add this as a suffix for emergency cases (e.g. IIIE)

For some patients with significant comorbidities, liaison with the patient’s treating specialist may be useful. For example, if a patient with reduced exercise tolerance due to emphysema has not been reviewed by a respiratory physician for a long period of time, it would be reasonable for the respiratory physician to review the patient in order to optimise his or her periprocedural status and to help stratify the anaesthetic risk.

Patients who should be sedated by an anaesthetist

There is a group of patients in whom the risks of sedation are significantly increased, and for whom it is more appropriate for an anaesthetist to deliver sedation. This includes patients with severe comorbidities such as cardiac, pulmonary or renal disease who have an ASA grading over III (see Table 28.2). In addition, patients with abnormalities of the oropharynx, neck or airway are at increased risk of airway problems if oversedation occurs (see Box 28.2). Patients at extremes of age, who abuse alcohol or other drugs, are pregnant or who are planned for a procedure of long duration or in which deep sedation is required are also suitable to be referred to an anaesthetist. In addition, those with a high risk of having a large residual gastric content such as patients with a small bowel obstruction should be managed by an anaesthetist due to the increased risk of aspiration.

Box 28.2 Patients at increased risk of airway management problems

• History of sleep apnoea, stridor, or snoring
• Oral abnormalities such as loose teeth, small oral opening (less than 3 cm), or macroglossia
• Neck problems such as cervical spine disease or trauma, limited neck extension, obesity involving the neck and facial structures, short neck, tracheal deviation
• Previous airway problems in an anaesthetic
• Dysmorphic facial features such as in Pierre-Robin syndrome
• Jaw abnormalities such as micrognathia

Logistics of administering sedation

The logistics of administering sedation are very important, and if performed inadequately can create an unsafe situation with significant potential of an adverse event occurring. These issues include monitoring of the patient during and after the procedure, administration of anaesthetic agents, training and level of staffing, and protocols for managing emergencies. Communication between the proceduralist and nursing staff is critical in order to clearly communicate orders relating to sedation, and also to feed back to the proceduralist changes in the patient’s status that require attention. All staff should feel comfortable vocalising concerns about a patient’s status if they feel that the safety of a patient has been compromised, and not feel that doing so is inappropriate due to issues of hierarchy or seniority.

Monitoring of patients

All patients should be monitored during sedation in order to detect complications of sedation and allow early management of these problems. The most common adverse event during endoscopy is the development of respiratory depression and hypoxia due to the administration of sedative agents. In addition to respiratory effects, sedation can cause cardiovascular depression so blood pressure and heart rate should be monitored as well.

Pulse oximetry

Pulse oximetry is a non-invasive way of measuring arterial oxygen saturation (SaO2) by the use of a probe that measures the light signal transmitting through tissue and the pulsatile volume changes that occur. Because the oxyhaemoglobin dissociation curve is sigmoid in nature, the partial pressure of oxygen is maintained reasonably high when the SaO2 is above 90%; however, it quickly drops when the SaO2 drops below 90%. In this range, small drops in SaO2 correspond to large drops in oxygen partial pressure and are a signal that rapid attention to oxygen delivery and ventilation is required. Notably, pulse oximetry does not work as well when tissue perfusion is poor, such as when hypotension occurs during a procedure; low oxygen saturation should prompt a recheck of the blood pressure (the cuff should be on the opposite arm to avoid reducing perfusion to the pulse oximeter). Most importantly, there is a significant delay between hypoventilation (or apnoea) and reduction in SaO2.

Capnography

Although pulse oximetry provides some indication of when hypoxia has occurred, it is a relatively blunt tool to detect hypoventilation and apnoea, which can be further masked by the use of supplemental oxygen. An excellent way to monitor for hypoventilation is to use non-invasive capnography, which measures CO2 concentration in the vicinity of expired air. This is graphically represented as an oscillating line as the patient breathes in and out and the CO2 concentration changes. The actual CO2 level estimated is not critical. Rather, capnography demonstrates in real time that the patient is breathing. Capnography enables hypoventilation and apnoea to be detected immediately as reflected by a lack of oscillation in expired carbon dioxide (CO2). A capnograph probe can be used attached to a Hudson mask, and even attached to nasal prongs.

Blood pressure monitoring

Monitoring of blood pressure is best achieved via the use of an inflatable blood pressure cuff which is able to be automatically inflated at periodic intervals. Guidelines from the American Society of Gastrointestinal Endoscopy suggest measuring the blood pressure before the procedure, at the commencement of the procedure, at every 5 minutes during the procedure then at intervals in the recovery room. Ideally, the most recent blood pressure reading should be displayed on the screen of an electronic ‘mini-monitor’. The blood pressure cuff should not be placed on the same arm as the intravenous cannula or the pulse oximeter to prevent flow of sedation, and false pulse oximeter readings. For some patients, especially for those with a cardiac history such as arrhythmias or if deep sedation is performed, additional monitoring of an electrocardiography trace may be useful.

Medications used in sedation

Drugs used for sedation have a number of common properties. These drugs are often synergistic when used together rather than being cumulative, and as such care should be taken when drugs are coadministered. A given dose of a sedative can have a wide variation in sedative effect in different patients, so careful titration of dosages is important to avoid oversedation—there is no such thing as a ‘standard dose’. In addition, the peak effect of a medication may be delayed, and over-frequent administration of doses can also lead to oversedation, especially in the recovery room. It should be remembered that the key end point of sedation is patient comfort rather than complete unconsciousness, and in some situations it is perfectly reasonable for the patient to be awake during the procedure. Patient expectation is essential here—patients often complain of awareness during endoscopic procedures because they had the misconception that they would undergo general anaesthesia.

Unsedated endoscopy

Unsedated endoscopy can be performed in patients who have a high risk related to sedation or prefer not to be sedated; in some European and Asian countries less than 25% of patients are sedated for routine upper gastrointestinal endoscopy. This may reduce costs and risks associated with procedures, and enables patients to ‘walk out’ of the procedure room without the need for a recovery period; patients can go back to work with minimal disruption. This may be particularly useful in regions where mass screening for oesophageal or gastric cancer is practised. Since most patients find unsedated endoscopy disagreeable, the use of an ultra-thin endoscope or transnasal endoscope may make this more tolerable.

Benzodiazepines and opiates

A combination of a benzodiazepines and an opiate is commonly used for sedation during endoscopy. These drugs have the advantage of availability of reversal agents in the event of oversedation. Commonly used benzodiazepines include midazolam and diazepam. Midazolam has a more rapid onset, shorter half-life; produces less thrombophlebitis; and has better amnesic properties compared to diazepam. It should be remembered that benzodiazepines may lead to paradoxical agitation. The amnesic effect of benzodiazepines is very useful to minimise postprocedure distress, though this effect is very variable and should not be relied upon.

Commonly used opiates include fentanyl and meperidine (pethidine). Fentanyl, though more expensive, is a better agent than meperidine; it has a shorter half-life, produces less nausea and fewer allergic reactions and does not cause local injection site reactions.

Propofol

Propofol is an anaesthetic agent that acts by causing the release of gamma amino butyric acid in the brain. It is increasingly used in endoscopy due to its attractive properties such as rapid onset and offset, shortened recovery time, and fewer effects on neuropsychiatric functioning postprocedure. The half-life is 1–4 minutes, and the onset of sedation is within 30–60 seconds. Propofol is regarded as having a ‘narrow therapeutic window’ that can result in rapid depression to deep sedation or even general anaesthesia. In addition, hypotension can occur due to decreased systemic vascular resistance and negative cardiac inotropy. It has been approved by the US Food and Drug Administration for use by anaesthetists, but it is commonly used ‘off label’ by endoscopists for sedation. A meta-analysis of randomised controlled trials comparing propofol use during endoscopy to combined midazolam and opiates suggested that there were no differences in hypoxaemia, hypotension, the proportion of patients reporting pain or physician satisfaction, though patient satisfaction was higher in the propofol group. Furthermore, in contrast to benzodiazepines and narcotics there is no reversal agent. This means that a practitioner using propofol must be prepared to artificially ventilate an apnoeic patient for up to several minutes if necessary.

Generally propofol should not be used as a single agent as its analgesic effects are minimal, and it combines well with use of a small dose of opiate with or without a benzodiazepine at the beginning of the procedure.

Droperidol

Droperidol is a dopamine receptor antagonist in the same class as haloperidol, which has been used as an adjunct in patients who are difficult to sedate. However, it has a risk of cardiac arrhythmias, especially in higher doses and in patients with prolonged Q-T duration, and should be used with caution. Furthermore, it is long-acting, requiring a long recovery phase, and causes unpleasant dysphoria in many patients. For these reasons it is rarely used.

Pharyngeal anaesthesia

Topical anaesthetic throat sprays are sometimes used to suppress the gag reflex and so to facilitate upper endoscopic procedures. These agents are effective for up to an hour, though they may impair pharyngeal coordination. Therefore, patients should be warned not to eat or drink for at least 1 hour postendoscopy. There is conflicting data regarding the benefit of anaesthetic throat sprays as an adjunct to conventional sedation, though some clinicians use it routinely for all procedures. There is a risk of rare but potentially severe reactions such as methemoglobinemia. One approach is to limit its use to patients in whom minimal sedation or unsedated endoscopy is performed.

Intravenous cannulas and supplemental oxygen

The administration of sedative agents should be by means of a conveniently and securely placed intravenous cannula. ‘Butterfly needles’ may cut tissue out of the vein during the procedure and should not be used. Intravenous fluids can be useful in some cases, such as if the patient is dehydrated due to bowel preparation or due to fasting, if the patient has renal impairment, or if hypotension occurs during the procedure. Oxygen can be administered via nasal prongs when upper endoscopy is performed, and via a Hudson mask for colonoscopy.

Management of oversedation

Oversedation as manifested by reduced conscious state and respiratory depression or apnoea may initially manifest as a drop in oxygen saturation, though ideally it should be detected earlier by the clinical assessment of responsiveness (if conscious sedation is used), respiration or capnography. Initial management depends upon the degree of respiratory depression. This includes increasing supplemental oxygen (which may be administered via a Hudson mask rather than via nasal prongs), patient stimulation, airway management with the use of a ‘jaw thrust’ manoeuvre, and possibly withdrawal of the endoscope if gastroscopy is being performed. If these measures fail to resolve the situation, bag-and-mask ventilation should be performed and reversal medication such as flumazenil (for benzodiazepines) or naloxone (for opiates) should be administered. It should be noted that the half-life of these reversal agents is shorter than the active drugs, leading to the possibility that patients can slip back into deep sedation after the procedure. In practice this is a rare phenomenon. If the situation is deteriorating or additional help is required urgently, early notification of a medical emergency team is appropriate.

Staffing

The level of staffing depends upon the procedure being performed, but should ideally include a nurse to assist with the procedure such as the use of biopsy forceps, and a nurse allocated to monitor the patient and administer sedation. Training of staff with regard to the principles behind the use of sedative agents and management of oversedation is important, and regular training or education sessions should be attended. There should be at least one practitioner who has advanced resuscitation skills (such as endotracheal intubation, defibrillation and usage of resuscitation medications) available within 1–5 minutes. If propofol is used, a practitioner with experience in advanced life support should be dedicated solely to sedation and patient monitoring. Recently, the Australia and New Zealand College of Anaesthetists, Gastroenterology Society of Australia and Royal Australian College of Surgeons have prepared a statement on appropriate staffing for different patient settings and anaesthetic agents. A regularly checked resuscitation trolley or kit should be available with equipment for endotracheal intubation, and a defibrillator should be available within several minutes. However, the vast majority of adverse events are related to oversedation and will respond promptly to bag and mask ventilation.

Specific situations

In the case of acute upper tract gastrointestinal haemorrhage, sedation of the patient during endoscopy must take into account the increased risk of aspiration. An estimate of this risk can be made on clinical criteria such as presentation (haematemesis versus melaena), the amount of bleeding, the haemoglobin and the haemodynamic status. If the patient is thought to have a high risk of aspiration, sedation should be delivered by an anaesthetist with prophylactic endotracheal intubation. Administration of a prokinetic agent (such as intravenous erythromycin) half an hour before the procedure may aid in gastric emptying. Intensive resuscitation including administration of blood products prior to the procedure is important to minimise anaesthetic risks, though in some cases if bleeding is ongoing it may not be possible to normalise the haemodynamic status and the procedure should be performed emergently.

For patients presenting with an oesophageal foreign body, the risk of pulmonary aspiration of saliva or food contents is significantly increased. As such, for most patients endotracheal intubation should be performed prior to the procedure. Alternatively, the use of an overtube in the upper oesophagus may protect the airway.

Key Points

• Informed consent is critical to any endoscopic procedure. It is not merely a signed document, but rather a process whereby the patient comes to understand the indication and nature of a procedure as well as its risks, benefits and alternatives. There must be an opportunity for questions to be addressed.
• Adequate bowel preparation for colonoscopy is essential to reduce missed lesions. Hyperosmolar solutions such as sodium phosphate or sodium picosulfate-based preparations are usually better tolerated, but may lead to dehydration and must be used with caution in the elderly and those with renal impairment.
• Antibiotic prophylaxis is probably overused, but is important for ‘high risk’ patients undergoing ‘high risk’ procedures as well as mandatory for a few specific procedures (such as percutaneous endoscopic gastroenterostomy placement and drainage of pancreatic fluid collections).
• Diabetic patients comprise a special group requiring individualisation of their preparation for procedures, especially for those taking insulin.
• All endoscopic procedures can be safely performed while a patient is on aspirin.
• Therapeutic procedures such as polypectomy of significant polyps, stricture dilation and biliary sphincterotomy should not be preformed within a setting of anticoagulants such as warfarin or the newer antiplatelet agents such as clopidogrel. The management of these patients on these agents is complex and requires balancing the risk of the procedure and the potential consequences of cessation of the medication.
• A specific situation of note is the management of clopidogrel in patients with a recent coronary stent (especially a drug-eluting stent). The management of these patients must be done in collaboration with their cardiologist.
• All patients should undergo non-invasive monitoring during any sedated procedure including pulse, blood pressure and pulse oximetry. Capnography is very useful for those undergoing deep sedation in order to detect apnoea early.
• During any sedation an appropriately trained health professional whose sole purpose is to monitor the patient’s wellbeing must be present.
• The mainstay of endoscopic sedation is a combination of short-acting benzodiazepine and narcotic. For both of these drug classes an effective, immediate reversal agent is available and must be on hand.
• Propofol is used to provide ‘deep sedation’, never ‘conscious sedation’, and must only be used if staff are trained in advanced airway management.

Further reading

[Anonymous]. Practice guidelines for sedation and analgesia by non-anesthesiologists. Anesthesiology. 2002;96(4):1004-1017.

Australia and New Zealand College of Anaesthetists, Gastroenterology Society of Australia and Royal Australian College of Surgeons. PS9: guidelines on sedation and/or analgesia for diagnostic and interventional medical or surgical procedures, February 2008. Online.

Banerjee S., Shen B., Baron T.H., et al. Antibiotic prophylaxis for GI endoscopy. Gastrointest Endosc. 2008;67(6):791-798.

Burton J.H., Harrah J.D., Germann C.A., et al. Does end-tidal carbon dioxide monitoring detect respiratory events prior to current sedation monitoring practices? Academic Emergency Medicine. 2006;13(5):500-504.

Carbonell N., Pauwels A., Serfaty L., et al. Erythromycin infusion prior to endoscopy for acute upper gastrointestinal bleeding: a randomized, controlled, double-blind trial. Am J Gastroenterol. 2006;101(6):1211-1215.

Cohen L.B., DeLegge M.H., Aisenberg J., et al. AGA Institute review of endoscopic sedation. Gastroenterology. 2007;133(2):675-701.

Eisen G.M., Baron T.H., Dominitz J.A., et al. Guideline on the management of anticoagulation and antiplatelet therapy for endoscopic procedures. Gastrointest Endosc. 2002;55(7):775-779.

Evans L.T., Saberi S., Kim H.M., et al. Pharyngeal anesthesia during sedated EGDs: is ‘the spray’ beneficial? A meta-analysis and systematic review. Gastrointest Endosc. 2006;63(6):761-766.

Ladas S.D., Aabakken L., Rey J.F., et al. Use of sedation for routine diagnostic upper gastrointestinal endoscopy: a European Society of Gastrointestinal Endoscopy survey of McQuaid KR, Laine L. A systematic review and meta-analysis of randomized, controlled trials of moderate sedation for routine endoscopic procedures. Gastrointestinal endoscopy. 2008;67(6):910-923.

National Endoscopy Society members. Digestion. 2006;74(2):69-77.

Patel S., Vargo J.J., Khandwala F., et al. Deep sedation occurs frequently during elective endoscopy with meperidine and midazolam. Am J Gastroenterol. 2005;100(12):2689-2695.

Rex D.K. Review article: moderate sedation for endoscopy: sedation regimens for non-anaesthesiologists. Alimentary Pharmacology & Therapeutics. 2006;24(2):163-171.

Robin C., Trieger N. Paradoxical reactions to benzodiazepines in intravenous sedation: a report of 2 cases and review of the literature. Anesth Prog. 2002;49(4):128-132.

Sorbi D., Gostout C.J., Henry J., et al. Unsedated small-caliber esophagogastroduodenoscopy (EGD) versus conventional EGD: a comparative study. Gastroenterology. 1999;117(6):1301-1307.

Vargo J.J., Zuccaro G.Jr., Dumot J.A., et al. Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy. Gastrointest Endosc. 2002;55(7):826-831.

Veitch A.M., Baglin T.P., Gershlick A.H., et al. Guidelines for the management of anticoagulant and antiplatelet therapy in patients undergoing endoscopic procedures. Gut. 2008;57(9):1322-1329.

Related posts:

Nausea and vomiting Loss of appetite and loss of weight Heartburn, regurgitation and non-cardiac chest pain Lumps in the groin and hernia Rectal/perianal mass and colorectal cancer Perianal pain