異氟醚
異氟醚是獸醫學中廣泛使用的**吸入性全身麻醉劑**。 主要臨床特點包括： - **心血管安全性**：與舊型藥物（如氟烷）相比，其心肌抑制和兒茶酚胺致敏作用較小。 - **器官安全性**：肝臟代謝極少（僅約0.17%），對於已有肝腎疾病的病患是安全的選擇。 - **臨床要點**：雖然新型藥物（如七氟醚）能更快改變麻醉深度且面罩誘導更平順，但異氟醚在獸醫麻醉中仍是高度可靠且具成本效益的常規用藥。
作用機制: The exact mechanism of inhalant anesthetics remains partially understood, but they are believed to act on the **lipid matrix of neuronal membranes** and interact with various ligand-gated ion channels (e.g., **GABA_A receptors**) in the brain and spinal cord. Key physiological effects: - **CNS**: Reversible depression, altered temperature regulation, increased cerebral blood flow. - **Cardiovascular**: Dose-dependent hypotension (primarily via **vasodilation** rather than direct myocardial depression). - **Respiratory**: Dose-dependent respiratory depression. > **MAC (Minimum Alveolar Concentration)** values: Dog = 1.5%; Cat = 1.2%; Horse = 1.31%.
各物種劑量
- Anesthesia · 5% induction; 1.5-2.5% maintenance · Inhalation · Continuous · As needed · Concentrations are dependent upon fresh gas flow rate
- Anesthesia · 0.5-3%, inhaled · Inhalation · Continuous · As needed
- Maintenance of surgical anaesthesia · MAC is approximately 1.6% · Inhalational · Continuous · Duration of surgery · Adjust based on individual requirement and premedication.
- Anesthesia · Starting isoflurane at 1-2% · Inhalation · Continuous · As needed · After premed with medetomidine. Use a non-rebreathing system.
- Anesthesia · 4% · Inhalation · Continuous · As needed · Small birds can be anesthetized safely in 15-30 seconds
- Anesthesia · Induction occurs within 1-2 minutes at a concentration of 3-5%. Maintenance at 1.5-2% · Inhalation · Continuous · As needed · Anesthetic of choice for birds. Recovery is very rapid.
- Anesthesia (Mice, Rats, Gerbils, Hamsters, Guinea pigs, Chinchillas) · Induction: 2-3%, maintenance: 0.25-2% · Inhalation · Continuous · As needed · Using a non-rebreathing system
- Anesthesia · Give 5% isoflurane and oxygen in a clear plastic bag or induction chamber. Maintenance levels are 3-5% (if isoflurane used alone). · Inhalation · Continuous · As needed · Induction time may take 30-60 minutes. Can be shortened with ketamine premedication.
- Anesthesia · Maintenance is usually 1.5-3%. · Inhalation · Continuous · As needed · Anesthetic gas of choice for reptiles.
- Anesthesia · 5% induction; 1.5-2.5% maintenance · Inhalation · Continuous · As needed · Concentrations are dependent upon fresh gas flow rate
- Anesthesia · 0.5-3%, inhaled · Inhalation · Continuous · As needed
- Induction of anaesthesia (unpremedicated) · 3-5% expired concentration · Inhalational · Continuous until induced · As needed · Adjust based on individual requirement and premedication.
- Maintenance of surgical anaesthesia · MAC is approximately 1.2% · Inhalational · Continuous · Duration of surgery · Administration of other anaesthetic agents and opioid analgesics reduces the dose requirement. Adjust to clinical depth.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- History or predilection towards malignant hyperthermia
- Known susceptibility to malignant hyperthermia
不良反應
- Dose-related hypotension
- Respiratory depression
- Nausea and vomiting
- Ileus
- Minimal cardiodepression
- Rare arrhythmias
- Dose-dependent hypotension (due to vasodilation, particularly in skeletal muscle)
- Dose-dependent respiratory depression
- Arrhythmias (less arrhythmogenic than halothane, but possible under certain conditions)
- Hypothermia
藥物相互作用
- Aminoglycosides · Additive neuromuscular blockade may occur
- ACE Inhibitors or Hypotensive Agents · Concomitant use may increase risks for profound hypotension
- Lincosamides · Additive neuromuscular blockade may occur
- Non-depolarizing Neuromuscular Blocking Agents · Additive neuromuscular blockade may occur · moderate
- Succinylcholine · May induce increased incidences of cardiac effects (bradycardia, arrhythmias) and malignant hyperthermia in susceptible patients
- Sympathomimetics (dopamine, epinephrine, etc.) · May result in arrhythmias, though isoflurane sensitizes the myocardium less than halothane. Use with caution and intensive monitoring.
- Sedatives (e.g., alpha-2 agonists, phenothiazines) · Reduces the concentration of isoflurane required to achieve surgical anaesthesia (MAC reduction). · moderate
- Opioid agonists · Reduces the concentration of isoflurane required to achieve surgical anaesthesia (MAC reduction). · moderate
- Nitrous Oxide (N2O) · Reduces the concentration of isoflurane required to achieve surgical anaesthesia. · moderate
監測
- Respiratory and ventilatory status
- Cardiac rate and rhythm
- Blood pressure (particularly in 'at risk' patients)
- Level of anesthesia
- Respiratory rate, rhythm, and depth (capnography/ETCO2 recommended)
- Heart rate and rhythm (ECG)
- Blood pressure (Doppler or oscillometric)
- Oxygen saturation (Pulse oximetry/SpO2)
- Body temperature
- Anaesthetic depth (eye position, palpebral reflex, jaw tone)
過量
Overdose risks are increased with intermittent positive pressure ventilation. Profound hypotension may occur, which usually responds to IV fluids but may require the use of vasopressors.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。