An investigation to augment cough response in anesthetized dogs

首先，我们验证了咳嗽时胸内支气管收缩的假设。在气管造口犬中，用球囊末端导管连续测量第五代支气管的直径。所有犬在咳嗽爆发期支气管收缩。然后对狗进行迷走神经切除术，并通过连续施加气道正负压来模拟咳嗽。当支气管收缩时，爆发力峰值明显降低，节段支气管气道压力减小。这些发现提示支气管收缩通过将阻塞点移动到近端气道而增加咳嗽。在第二项研究中，我们研究了增强咳嗽的方法。咳嗽引起机械刺激气管分叉使用导线插入低颈部。在气管刺激同时进行声带机械刺激时，咳嗽强度参数（平均胸膜压、平均呼气流量）增加。静脉注射氨茶碱后引起咳嗽时，咳嗽强度的参数也增加。我们推测，在麻醉狗的神经输入从上呼吸道增强咳嗽反应。

Firstly we tested the hypothesis that the intrathoracic bronchi constrict during cough. In the tracheostomized dogs, diameter of the fifth-generation bronchus was continuously measured with a balloon-tipped catheter. The bronchus constricted in explosive phase of cough in all the dogs. Then the dogs were vagotomized and the cough was simulated by sequential application of positive and negative airway pressures. The peak explosive flow significantly decreased and airway pressure in the segmental bronchus became smaller when the bronchi were constricted. These findings suggested that bronchial constriction augments cough by moving choke point to proximal airway.In the second study we investigated method to augment cough. Coughing was elicited with mechanical stimulation of tracheal bifurcation using a wire inserted through low neck. When mechanical stimulation of vocal chord was applied concurrently with tracheal stimulation, the parameters of cough strength (mean pleural pressure, mean expiratory flow) increased. The parameters of cough strength also increased when cough was elicited after intravenous aminophylline. We speculated that in the anesthetized dog neural inputs from the upper airway augment cough response.