多沙普侖
多沙普侖（Doxapram）是一種中樞神經系統（CNS）和呼吸興奮劑。在獸醫學中，它主要用於麻醉期間或麻醉後的呼吸刺激，以加速甦醒。它在輕度麻醉下**評估喉部功能**（如診斷喉頭麻痺）時也具有獨特的價值，因為它能刺激深吸氣動作，使杓狀軟骨的運動更容易被觀察評估。 > **臨床重點：** 過去常規將此藥物（通常經舌下或臍靜脈給藥）用於難產或剖腹產後新生兒的呼吸急救。**但目前此用法備受爭議。** 多沙普侖會顯著增加心肌與腦部的耗氧量，對於已經處於缺氧狀態的新生兒可能會造成損害。現今的新生兒急救指南強烈建議優先使用清除呼吸道、提供氧氣以及正壓人工呼吸（機械性通氣支持），而非依賴此類中樞興奮藥物。
作用機制: Doxapram is a generalized CNS stimulant. Its respiratory effects are primarily driven by: 1. **Direct stimulation** of the **medullary respiratory centers**. 2. **Reflex activation** of peripheral **carotid and aortic chemoreceptors**. This dual action leads to transient increases in tidal volume and respiratory rate. > **Mechanistic Note:** While doxapram increases respiratory effort, it simultaneously increases the overall work of breathing, metabolic rate, and carbon dioxide production. Consequently, it does not reliably improve arterial oxygenation, which is why it cannot replace mechanical ventilation in severely hypoxic patients.
各物種劑量
- Gas anesthesia recovery · 1.1 mg/kg IV · IV · May repeat in 15-20 minutes if necessary · Adjust dosage for depth of anesthesia, respiratory volume and rate.
- Barbiturate anesthesia recovery · 5.5-11 mg/kg IV · IV · May repeat in 15-20 minutes if necessary · Adjust dosage for depth of anesthesia, respiratory volume and rate.
- To initiate or stimulate respirations in neonates after caesarian section or dystocia · 1-2 drops (1-2 mg) SC or sublingually · SC/SL · Once · Depending on severity of respiratory crisis.
- To stimulate respiratory function in neonates · 0.1 mL (2 mg) IV (IM or SL also possible) · IV/IM/SL · Once · Most likely to be beneficial to increase efforts in neonates with low-frequency, gasping, erratic pattern of breathing after receiving oxygen therapy.
- Primary apnea in asphyxic calves when intubation and mechanical ventilation are not feasible · 2 mg/kg IV · IV · Once · Contraindicated in premature calves or other patients with clinical signs indicative of lung immaturity.
- Primary apnea in newborn calves · 2 mg/kg IV · IV · Once
- Halothane, methoxyflurane anesthesia recovery · 0.44 mg/kg IV · IV · May repeat in 15-20 minutes if necessary · Adjust dosage for depth of anesthesia, respiratory volume and rate. ARCI UCGFS Class 2 Drug.
- Chloral hydrate ± magnesium sulfate anesthesia recovery · 0.55 mg/kg IV · IV · May repeat in 15-20 minutes if necessary · Adjust dosage for depth of anesthesia, respiratory volume and rate. ARCI UCGFS Class 2 Drug.
給藥途徑
禁忌症
- Patients receiving mechanical ventilation
- Hypersensitivity to doxapram
- Seizure disorders
- Head trauma or cerebrovascular accidents (CVA)
- Uncompensated heart failure
- Severe hypertension
- Respiratory failure secondary to neuromuscular disorders
- Airway obstruction
- Pulmonary embolism
- Pneumothorax
- Acute asthma
- Dyspnea
- Hypoxia not associated with hypercapnia
- Premature calves or patients with clinical signs of lung immaturity
不良反應
- Hypertension
- Arrhythmias
- Tachycardia
- Seizures (at high doses)
- Hyperventilation leading to respiratory alkalosis
- Increased myocardial oxygen demand
- Reduced cerebral blood flow
- Skeletal muscle hyperactivity
藥物相互作用
- General Anesthetics (e.g., halothane, enflurane) · Doxapram may increase epinephrine release and sensitize the myocardium to catecholamines. Use should be delayed for ~10 minutes after discontinuing these anesthetics.
- Muscle Relaxants · Doxapram may mask the effects of muscle relaxant drugs.
- Sympathomimetic Agents · Additive pressor (blood pressure increasing) effects may occur.
監測
- Respiratory rate and effort
- Cardiac rate and rhythm
- Blood gases (if available and indicated)
- CNS level of excitation and reflexes
- Blood pressure (if indicated)
過量
The reported LD50 for IV administration in neonatal dogs and cats is approximately 75 mg/kg. **Clinical signs of overdosage include:** - Respiratory alkalosis - Hypertension - Skeletal muscle hyperactivity - Tachycardia - Generalized CNS excitation, including seizures **Treatment:** Treatment is primarily supportive. Drugs such as short-acting IV barbiturates may be used to help decrease CNS hyperactivity. Oxygen therapy may be necessary.
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