Practical Clinical Anesthesia Handbook

Author: Song Defu (Editor) / Country:
Publisher:
Publish Date: 2004-03-01
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Six. Propofol Intravenous Anesthesia Propofol is a hypnotic intravenous anesthetic. Its characteristics include rapid onset, strong hypnotic effect, short duration, and quick recovery.
1. Anesthesia Methods (1) Anesthesia Induction: Induction drugs for general anesthesia in various surgical disciplines. Due to its minimal impact on the circulatory system, it can be used as an induction agent for patients with shock and poor cardiac function, as well as cardiovascular surgery patients. The adult dose is 0.3 mg/kg (0.1–0.4 mg/kg). (2) Anesthesia Maintenance: Pure intravenous propofol anesthesia is suitable only for short procedures. For medium to long surgeries, it must be combined with other intravenous anesthetics, inhaled anesthetics, or other anesthesia methods to meet surgical needs. The adult dose remains 0.3 mg/kg (0.1–0.4 mg/kg).
2. Indications (1) General anesthesia induction, often used in combination with muscle relaxants for tracheal intubation, commonly employed in cardiovascular surgery and critical cases, as well as anesthesia induction and maintenance for patients with poor cardiac function. (2) Short procedures, such as induced abortion and incisional drainage. (3) Special examinations, such as gastroscopy, bronchoscopy, and endoscopic examinations. (4) Adjunctive anesthesia, such as spinal anesthesia and various nerve block anesthetics.
3. Contraindications (1) Severe diabetic patients. (2) Patients with hyperkalemia.
4. Precautions (1) Propofol has no analgesic effect and requires the use of fentanyl or pethidine to enhance analgesia for complete anesthesia. Muscle relaxants are necessary for thoracic and abdominal surgeries. (2) It has a synergistic effect with succinylcholine, so they should not be used together. However, a single dose of succinylcholine can be administered before tracheal intubation. (3) Muscle tremors may occur during anesthesia and can be prevented or treated with diazepam, fentanyl, or droperidol. (4) Non-emulsion formulations may cause significant pain at the injection site. (5) There is a hypothesis that prolonged use of propofol inhibits adrenal cortical function, but this remains under investigation and is still controversial.
Seven. Procaine Intravenous Anesthesia Procaine is an ester-based local anesthetic.
1. Anesthesia Methods (1) After rapid induction of tracheal intubation with intravenous anesthetics and muscle relaxants, anesthesia is maintained. In the first hour, 1% procaine 250–300 mL and pethidine 100–200 μg are administered. (2) Thereafter, 1% procaine solution is infused at a rate of 100–200 mL/h. (3) If the surgery extends, the hourly dose of procaine should be gradually reduced. Pethidine and propofol may be added if necessary. (4) Combination with other drugs, such as intravenous anesthetics, inhaled anesthetics, analgesics, and muscle relaxants. Non-depolarizing muscle relaxants are infused, while depolarizing muscle relaxants are administered intermittently to maintain anesthesia.
2. Precautions (1) Procaine cannot be used alone for intravenous anesthesia and must be used in combination with other anesthetics. (2) If the anesthesia is shallow, procaine cannot be used to deepen it; other anesthetic drugs must be used instead. (3) If the anesthesia is too deep, it may cause hypotension, decreased pulse pressure, and tachycardia. The drug should be stopped immediately, and pressor drugs should be administered. (4) If unexplained decreases in blood oxygen partial pressure and SpO2 occur during anesthesia, the infusion of procaine should be stopped immediately. The mechanism of this phenomenon is still under investigation. (5) Excessive procaine dosage may lead to convulsions. In cases of severe acute toxicity, pure oxygen should be administered, and 2.5% thiopental sodium or a muscle relaxant should be given intravenously to control symptoms. Procaine infusion should be stopped immediately; otherwise, respiratory and cardiac arrest may occur.
Eight. Neuroleptanalgesia
1. Anesthesia Methods (1) Common formulations of the neuroleptanalgesic mixture: A unit is prepared by mixing 5 mg of droperidol with 0.1 mg of fentanyl (a 50:1 ratio), known as the fentanyl-droperidol combination. (2) Anesthesia Induction: 5 mg of droperidol and 0.1–0.2 mg of fentanyl are administered intravenously. Dosage should be reduced for elderly or frail patients. Better results are achieved when combined with other intravenous drugs, such as diazepam or propofol. The use of the fentanyl-droperidol combination alone is not ideal due to the significant impact of high droperidol dosage on blood pressure. (3) Anesthesia Maintenance: The fentanyl-droperidol combination is added as needed based on the patient's condition and pain response, with 0.5 units added every 30–60 minutes. Most clinical practitioners now advocate adding only fentanyl to facilitate recovery.
2. Indications (1) Surgery in various disciplines and locations. (2) Debridement and skin grafting for severe burns. (3) Various endoscopic examinations and contrast studies. (4) Adjunctive anesthesia for local anesthesia, nerve blocks, and epidural anesthesia. (5) Patients requiring prolonged mechanical ventilation postoperatively for respiratory support. (6) Sedation for ICU patients.
3. Contraindications (1) Short procedures. (2) Infants and children. (3) Cesarean delivery. (4) Patients with Parkinson's disease or epilepsy. (5) Severe respiratory insufficiency and bronchial asthma.
4. Precautions (1) If droperidol dosage exceeds 25 mg and extrapyramidal symptoms occur, 15 mg of promethazine may be administered intravenously, or 5–10 mg of chlorpromazine or 5–10 mg of diazepam to control symptoms. (2) Other precautions are the same as those for fentanyl.