Chapter 24 General Anesthetics and Therapeutic Gases PDF

24 Chapter GENERAL PRINCIPLES OF SURGICAL ANESTHESIA Hemodynamic Effects of General Anesthesia Respiratory Effects of General Anesthesia General Anesthetics and Therapeutic Gases...

24 Chapter GENERAL PRINCIPLES OF SURGICAL ANESTHESIA Hemodynamic Effects of General Anesthesia Respiratory Effects of General Anesthesia General Anesthetics and Therapeutic Gases Jerry Ingrande, Matthew L. Pearn, and Hemal H. Patel INHALATIONAL ANESTHETICS Pharmacokinetic Principles Specific Inhalational Agents Hypothermia Nausea and Vomiting ANESTHETIC ADJUNCTS Other Emergent and Postoperative Phenomena Benzodiazepines α2 Adrenergic Agonists ACTIONS AND MECHANISMS OF GENERAL ANESTHETICS Analgesics The Anesthetic State Neuromuscular Blocking Agents Mechanisms of Anesthesia Anesthetic Administration in Special Populations Anatomic Sites of Anesthetic Action THERAPEUTIC GASES PARENTERAL ANESTHETICS Oxygen Pharmacokinetic Principles Carbon Dioxide Specific Parenteral Agents Nitric Oxide Novel Parenteral Anesthetics Helium Hydrogen Sulfide General anesthetics depress the CNS to a sufficient degree to permit the generally must be assisted or controlled for at least some period dur- performance of surgery and unpleasant procedures. General anesthetics ing surgery. The gag reflex is lost, and the stimulus to cough is blunted. have low therapeutic indices and thus require great care in administra- Lower esophageal sphincter tone also is reduced, so both passive and tion. The selection of specific drugs and routes of administration to pro- active regurgitation may occur. Endotracheal intubation has been a major duce general anesthesia is based on the pharmacokinetic properties and reason for a decline in the number of aspiration deaths during general on the secondary effects of the various drugs. The practitioner should anesthesia. Muscle relaxation is valuable during the induction of general consider the context of the proposed diagnostic or surgical procedure and anesthesia where it facilitates management of the airway, including endo- the individual patient’s characteristics and associated medical conditions tracheal intubation. Neuromuscular blocking agents commonly are used when choosing appropriate anesthetic agents. to effect such relaxation (see Chapter 13). Alternatives to an endotracheal tube include a face mask and a laryngeal mask, an inflatable mask placed General Principles of Surgical Anesthesia in the oropharynx forming a seal around the glottis. Airway management techniques are based on the anesthetic procedure, the need for neuro- The administration of general anesthesia is driven by three general muscular relaxation, and the physical characteristics of the patient. objectives: 1. Minimizing the potentially deleterious direct and indirect effects of anes- Hypothermia thetic agents and techniques. Patients commonly develop hypothermia (body temperature