TY - CHAP M1 - Book, Section TI - Adjuncts to Anesthesia A1 - Butterworth IV, John F. A1 - Mackey, David C. A1 - Wasnick, John D. PY - 2022 T2 - Morgan & Mikhail’s Clinical Anesthesiology, 7e AB - KEY CONCEPTS Diphenhydramine is one of a diverse group of drugs that competitively blocks H1 receptors. Many drugs with H1-receptor antagonist properties have considerable antimuscarinic, or atropine-like, activity (eg, dry mouth) or antiserotonergic activity (antiemetic). H2 blockers reduce the perioperative risk of aspiration pneumonia by decreasing gastric fluid volume and raising the pH of gastric contents. Metoclopramide increases lower esophageal sphincter tone, speeds gastric emptying, and lowers gastric fluid volume by enhancing the stimulatory effects of acetylcholine on intestinal smooth muscle. Ondansetron, granisetron, tropisetron, and dolasetron selectively block serotonin 5-HT3 receptors, with little or no effect on dopamine receptors. Located peripherally and centrally, 5-HT3 receptors appear to play an important role in the initiation of the vomiting reflex. Ketorolac is a parenteral nonsteroidal anti-inflammatory drug that provides analgesia by inhibiting prostaglandin synthesis. Clonidine is a commonly used antihypertensive agent, but in anesthesia, it is used as an adjunct for epidural, caudal, and peripheral nerve block anesthesia and analgesia. It is often used in the management of patients with chronic neuropathic pain to increase the efficacy of epidural opioid infusions. Dexmedetomidine is a parenteral selective α2-agonist with sedative properties. It appears to be more selective for the α2-receptor than clonidine. Selective activation of carotid chemoreceptors by low doses of doxapram stimulates hypoxic drive, producing an increase in tidal volume and a slight increase in respiratory rate. Doxapram is not a specific reversal agent and should not replace standard supportive therapy (ie, mechanical ventilation). Naloxone reverses the agonist activity associated with endogenous or exogenous opioid compounds. Flumazenil is useful in the reversal of benzodiazepine sedation and the treatment of benzodiazepine overdose. Aspiration does not necessarily result in aspiration pneumonia. The seriousness of the lung damage depends on the volume and composition of the aspirate. Patients are at risk if their gastric volume is greater than 25 mL (0.4 mL/kg) and their gastric pH is less than 2.5. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1190604998 ER -