Chapter 91

### INTRODUCTION

Sedation and analgesia comprise a wide range of states; from anxiolysis to general anesthesia. The American Society of Anesthesiologists (ASA) has defined four levels of sedation: minimal, moderate, deep, and general. These levels are defined by four physiologic responses: responsiveness, airway, spontaneous ventilation, and cardiovascular function (see Chapter 90). Given the wide range of environments and settings that anesthesia can be delivered, the ASA developed guidelines to guide the practice of sedation and analgesia by non-anesthesia providers.

### PREPROCEDURAL ASSESSMENT

A thorough preprocedural and major organ diseases assessment of a patient is one of the best tools to anticipate and minimize potential morbidity and mortality in the delivery of an anesthetic. Providers need to be aware of previous sedation-related adverse events of the patient’s medical history, including current drug regimen, allergies, Nil per os (NPO) status, and pregnancy status. A thorough physical examination includes the patient’s weight, vital signs, pain level, oxygen saturation, airway assessment, general neurologic status, and level of consciousness; in particular, factors such as sleep apnea history, receding chin, obesity, small mouth opening, and limited neck extension which can be associated with difficult airway management. Preoperative studies are guided to more thoroughly assess preexisting medical conditions and their impact on sedation/analgesia. The evaluation needs to be updated immediately before sedation is started.

#### Patient Selection Criteria

The goal of the preprocedural assessment is to identify “at risk” patients for whom the delivery of moderate sedation by non-anesthesia personnel may or may not be appropriate. A helpful tool in this assessment is the ASA classification system. Patients classified as ASA Class III-V and patients with special needs may not be candidates for sedation by non-anesthesiologists. These patients require further consultation with appropriate subspecialists and/or anesthesiologists to ensure safe and effective sedation. If a difficult airway is anticipated, providers should refer to an anesthesiologist.

#### Patient Preparation

Patients should have the anesthesia plan thoroughly explained to them, with all risks, benefits, and alternatives to sedation and analgesia. They should be informed of the preoperative guidelines to fasting and their importance in reducing the risk of pulmonary aspiration of gastric contents. Pros and cons of sedation should be weighed in patients with recent oral intake and with other risk factors for regurgitation (such as emergency procedure, trauma, and decreased level of consciousness, obesity, and intestinal obstruction); particularly determining target levels of sedation, delay of procedure, or protection of trachea by intubation.

#### Monitoring

The key to avoiding complications is early recognition of adverse effects of sedative medications. These include respiratory or cardiovascular impairment or cerebral hypoxia. For moderate and deep sedation, the patient’s level of consciousness, ventilation, oxygenation, and hemodynamic measures should be recorded at a minimum during the following five components of the case: (1) preprocedural; (2) during administration of sedative-analgesic medications; (3) every 5 minutes ...

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