© Borgis - Nowa Medycyna 2/2017, s. 73-85
Risk assessment and monitoring in an adult patient for analgosedation during colonoscopy
Ocena ryzyka i monitorowanie u dorosłego pacjenta do analgosedacji podczas kolonoskopii
The Department of Anaesthesiology and Intensive Therapy, Saint Anna Traumatology Hospital, Mazovian Rehabilitation Centre „STOCER” Sp. z o.o., Warsaw
Head of Department: Elżbieta Kurmin-Gryz, MD
Analgosedacja to stan obniżonej świadomości pacjenta wywołany podaniem leku lub leków anestetycznych. Celem analgosedacji podczas kolonoskopii jest zapewnienie pacjentowi komfortu i poprawa warunków zabiegu endoskopowego, w szczególności bolesnego zabiegu leczniczego. Ważne jest, aby uświadomić sobie to, że częstość powikłań po endoskopii rośnie wraz z zastosowaniem analgosedacji. Dlatego należy rzetelnie ocenić ryzyko zastosowania analgosedacji przed wykonaniem zabiegu endoskopowego i zastosować odpowiednie monitorowanie pacjenta podczas kolonoskopii. Należy również zapewnić dostępność odpowiednio wyszkolonego zespołu anestezjologicznego i odpowiednio wyposażyć pracownię endoskopową w sprzęt anestezjologiczny. Najlepszym sposobem analgosedacji do kolonoskopii jest zindywidualizowanie analgosedacji dla konkretnego pacjenta uwzględniające: stan kliniczny pacjenta, jego poziom lęku, jak i rodzaj oraz czas trwania planowanego zabiegu kolonoskopowego. Leki anestetyczne używane w analgosedacji tłumią czynność układu nerwowego, układu sercowo-naczyniowego i układu oddechowego, przy czym stopień tłumienia może być dla niektórych pacjentów groźny. Celem pracy jest przedstawienie sposobów zwiększenia bezpieczeństwa pacjentów poddawanych kolonoskopii przez ocenę ryzyka analgosedacji, monitorowanie pacjenta podczas analgosedacji oraz w sali poznieczuleniowej.
Analgosedation is an anaesthetic drug-induced state of reduced consciousness. The purpose of analgosedation in colonoscopy is to increase patient’s comfort and improve endoscopic performance, especially in painful therapeutic procedures. It is important to realise that the rate of endoscopic complications is increased when analgosedation is used. Therefore, a thorough pre-procedural risk evaluation and intra-procedural monitoring of the patient should be performed. Properly trained anaesthesiological team and emergency equipment should be available. The best approach to analgosedation in colonoscopy is to choose a regimen for an individual patient, tailored according to the clinical risk assessment and the anxiety level of the patient, as well as to the type and duration of planned colonoscopy procedure. Agents used for analgosedation suppress central nervous, cardiovascular and respiratory function, and the varying degree of suppression may be fatal in certain patients. The aim of this article is to provide an overview and a brief summary of preanalgosedation risk assessment and patient monitoring during and after analgosedation to maintain patient safety.
Emotional excitation, which derives from CNS, endocrine and sympathetic activity, enhances the perception of pain. Elimination of shock and confusion as well as measures to calm the patient are important elements of treatment. This aspect is particularly important in colonoscopy. Patients usually report in the morning on the day of procedure, they receive no premedication and, following medical history collection and a brief introductory conversation, they undergo colonoscopy. They are usually discharged home several hours later. The current method of colonoscopy uses flexible devices made of elastic glass fibres as a basic optical element. This ensures practically full field of vision, as well as significantly enhances patient comfort during endoscopy and reduces procedure-related complications. Analgosedation may be defined as consciousness suppression induced by an anaesthetic agent(s). A recent survey-based research has shown that in most cases colonoscopy is performed using analgosedation (1-3). Anaesthetic agents used in analgosedation for endoscopy vary depending on the clinical centre. In some centres only one agent is used, whereas in other centres analgesics are combined with anaesthetics. Colonoscopy is most often performed in a patient in left side-lying position. During the examination, patients may change their position to supine or even right side-lying position. Colonoscopy and sigmoidoscopy are the most reliable methods in the diagnosis of colonic and rectal diseases. Indications for colonoscopy are presented in table 1. Administration of analgesics and anaesthetics enhances patient’s tolerance of discomfort and pain, thereby improving diagnostic and therapeutic endoscopic findings (4). Proper analgosedation ensures patient’s comfort and allows for cooperation with the endoscopist. It also allows for the maintenance of defensive airway reflexes and stable spontaneous breathing. This level of analgosedation was defined by the American Society of Anesthesiologists (ASA) as moderate (5) (tab. 2). Although centrally acting analgesics and anaesthetics suppress CNS function in a dose-dependent manner, there is an interindividual variability in the susceptibility to different medications; therefore the level of analgosedation may change rapidly, ranging from minimal sedation to general anaesthesia. Unintentionally deep sedation may impair respiratory and circulatory function, and thus put some patients at danger. The incidence of dangerous cardiovascular and respiratory complications during analgosedation in endoscopic procedures is estimated at 0.54% (6), with mortality rates of 0.05% (7). Patients undergoing elective endoscopic procedures under analgosedation should be subject to a thorough assessment, including medical history and current clinical condition. When monitoring a patient during analgosedation for colonoscopy, attention should be paid to respiratory and cardiovascular instability.
Tab. 1. Indications for colonoscopy
1. faecal occult blood
2. blood in the stool in the absence of evidence for the anal or rectal source of bleeding
3. tarry stools after excluding the source of bleeding in the upper gastrointestinal tract
4. unexplained iron deficiency
5. abnormalities in contrast infusion (contrast filling defect, a narrowing)
6. exclusion of synchronous cancers and polyps in patients with confirmed colorectal polyps and/or cancer
7. chronic diarrhoea of unknown origin
8. selected patients with altered rhythm of bowel movements and an increased risk of colorectal cancer
9. inflammatory bowel diseases if the diagnosis and determination of the extent of lesions affects the procedure
1. polyp removal
2. inhibition of bleeding due to developmental vascular abnormalities
3. foreign body removal
4. decompression of acute bowel subobstruction or torsion
5. dilation of stenosis
6. palliative treatment of inoperable stenosis or tumour bleeding
1. a history of colorectal cancer or adenomatous colon polyps
2. a family history of colorectal cancer not associated with polyposis
3. colorectal cancer in a first-degree relative under the age of 55 years or in more than one family member
4. long-term (more than 7-10 years) history of ulcerative colitis with extensive lesions, with collection of multiple biopsy specimens to detect dysplasia; inflammation limited to the left colon, no need for such intensive supervision
5. colonoscopy in patients over 50 years of age, every 10 years until the age of 70 years or once in lifetime
Tab. 2. American Society of Anesthesiologists classification for sedation
| ||Depth of sedation|
|response assessment||maintained response to verbal instructions||somnolence, maintained response to voice and pain if needed ||asleep, difficult to arouse, maintained response to pain stimulus||unconscious, not arousable, no response to pain stimulus|
|airways||no effects||no intervention is needed||intervention may be needed||intervention is often needed|
|spontaneous respiration||no effects on spontaneous respiration||efficient spontaneous respiration||moderately impaired spontaneous respiration|
|inefficient spontaneous respiration, assisted ventilation is needed|
|cardiovascular function||no effects||usually not impaired||usually not impaired||possible impairment|
Each patient should undergo a preliminary medical history evaluation and physical examination to determine indications and exclude potential contraindications for colonoscopy. Colonoscopy requires appropriate preparation involving bowel cleansing or refraining from consuming meals, which is important for patients with diabetes, cardiovascular insufficiency and renal failure, where modification of recommendations may be necessary. All patients should be informed on the benefits and the risks associated with the proposed procedure, give their oral and written consent for the procedure and receive guidelines on the preparation for the examination. Since a number of anaesthetics used in analgosedation have a narrow safety margin, patients often respond differently to the same anaesthetic doses, which requires increased vigilance when evaluating the general condition of a patient prior to colonoscopy using analgosedation.
Medical history and current health status
Preparation of a patient for sedation and general anaesthesia as well as the risk of general anaesthesia are assessed by an anaesthetist. Patients with comorbidities should be evaluated at appropriate time before the procedure. Medical history evaluation should exclude or confirm significant heart and lung disease, sleep apnoea and snoring, difficult previous intubation, epilepsy or other neurological condition, previous adverse effects of sedation and general anaesthesia, currently used medications, hypersensitivity to medications or food products, alcohol or psychoactive substance abuse, a recent meal within the last 6 hours and ingestion of clear liquid within the last 2 hours, nausea and vomiting suggesting an increased risk of aspiration. Physical examination should assess the state of consciousness, vital functions and body weight; determine the presence of obesity, ascitic fluid, gastrointestinal obstruction and increased abdominal circumference, which increase the risk of pulmonary aspiration. Medical history collection and physical examination should be followed by ASA classification, and the obtained score should be documented in the anaesthesia record. Special attention should be paid to patients with ASA score of 3 and above, Mallampati score of 3 and 4, a history of adverse reactions during sedation, inadequate sedation using standard doses of sedatives, a history of difficult intubation, alcohol and psychoactive substance abuse, sleep apnoea, indications for emergent endoscopy, as well as those undergoing a particularly technically difficult and long-lasting endoscopic procedure.
Antithrombotic and antiplatelet agents
Acetylsalicylic acid used as primary prevention of cardiovascular events should be discontinued 5-7 days before the procedure. For secondary prevention, discontinuation of acetylsalicylic acid (5-7 days before the procedure) as well as clopidogrel and ticlopidine (7-10 days before the procedure) is recommended. Temporary treatment with low molecular weight heparin should be considered in this group of patients. If the patient requires dual antiplatelet therapy, the mode of pre-procedural preparation should be consulted with a cardiologist. Treatment with acenocoumarol and warfarin should be discontinued 4-5 days before the procedure and heparin should be administered (8, 9).
Airway assessment should be based on Mallampati classification (fig. 1) to identify patients at an increased risk of difficult tracheal intubation. The Mallampati score is a four-point scale determining intubation difficulty based on the anatomy of the oral cavity. The distances between the uvula, the fauces and the soft palate are taken into account. High class (Mallampati class IV) indicates potentially difficult intubation. The score was introduced by Mallampati et al. in 1985 (10). This four-point scale includes the following scoring: class 1 – visible soft palate, uvula, pharynx, tonsils; class 2 – visible soft palate and uvula; class 3 – visible soft palate and base of uvula; class 4 – soft palate not visible at all. Other anatomical features may also impede positive inspiratory pressure ventilation and endotracheal intubation and these include obesity, short thick neck, cervical spine diseases, anatomical pathologies of the mouth, mandible and oral cavity, as well as reduced submental- discoid distance. Particular caution should be used in patients with ASA class 3 or above, Mallampati score of 3 and 4, a history of adverse reactions during sedation, inadequate sedation with standard doses of sedatives, a history of difficult intubation, alcohol or psychoactive substance abuse, sleep apnoea, indications for emergent endoscopy, as well as those undergoing a particularly technically difficult and long-lasting endoscopic procedure. It should be noted that some technically difficult colonoscopy procedures may require general anaesthesia with tracheal intubation.
|visible pillars, soft palate and uvula||visible soft palate and uvula||only soft palate visible||soft palate not visible|
Fig. 1. Mallampati classification system
Presedation fasting for colonoscopy
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