On the Operation of Transfusion in Obstetric Practice: With Description of a More Convenient Transfusion-Apparatus

Abstract

<b>Rationale</b>. Inhibition of slowly adapting stretch receptors (SARS) inhibits the cough reflex (CR), but it is not clear whether SARS stimulation facilitates CR and/or expiration reflex (ER). The issue is relevant to the long term understanding of chronic cough because those mechanisms that regulate cough are poorly understood. The <b>aim of the study</b> was to demonstrate whether SARS stimulation by continuous positive airway pressure (CPAP) alters CR and/or ER in the rabbit. <b>Methods</b>: 5 rabbits were anesthetized and tracheostomized. The trachea was exoposed to punctuate mechanical stimuli at control and with 4-5 hPa CPAP. 24 stimulations were aimed in each condition in each animal. CR and ER were identified from airflow and volume signals, diaphragmatic and abdominal muscle electrical activity. The reflexes were defined as a forced expiratory effort preceded (CR) or not (ER) by an augmented inspiration. Mixed responses were differentiated from the pattern of the first breath as ER/CR and CR/ER. <b>Results:</b> 241 stimulations, evenly distributed in inspiration and expiration, were obtained at control (n = 121) and on CPAP (n = 120). The overall incidence of positive responses significantly increased from 66% at control to 85% on CPAP (p = 0.0005). Incidence of ER, CR or CR/ER was not significantly altered. In contrast the mixed ER/CR response significantly increased from 14% at control to 38% on CPAP (p = 0.0005). <b>Conclusions</b>. SARS stimulation up regulates airway defensive reflexes, namely ER/CR. Thus SARS appear to sensitize preferentially those ER-facilitated coughs. It is speculated that a proper identification of airway defensive responses in patients may be relevant to a better understanding of chronic cough.