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.

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.

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.

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).