The implantable Doppler system is more effective than the conventional methods used to monitor free flap perfusion. The mean flap salvage rate with the implantable Doppler was 21 percentage points higher (81.4 vs. 60.4). The excess cost compared to conventional methods was about CAD 120 per patient (about EUR 94). However, this excess cost can be compensated or even reversed, depending on the initial flap salvage rate in the health facility and the type of free flap (buried vs. non-buried).

-Bussière, Pierre-Hugues Fortier, and Jean-Paul Praud. Laryngeal chemoreflexes induced by acid, water, and saline in nonsedated newborn lambs during quiet sleep.

No abstract

It has been suggested that reflux laryngitis (RL) is involved in apneas-bradycardias of the newborn. The aim of the present study was to develop a unique RL model in newborn lambs to test the hypothesis that RL enhances the cardiorespiratory components of the laryngeal chemoreflexes (LCR) in the neonatal period. Gastric juice surrogate (2 ml of normal saline solution with HCl pH 2 + pepsin 300 U/ml) (RL group, n = 6) or normal saline (control group, n = 6) was repeatedly injected onto the posterior aspect of the larynx, 3 times a day for 6 consecutive days, via a retrograde catheter introduced into the cervical esophagus. Lambs instilled with gastric juice surrogate presented clinical signs of RL, as well as moderate laryngitis on histological observation. Laryngeal chemoreflexes were thereafter induced during sleep by injection of 0.5 ml of HCl (pH 2), ewe's milk, distilled water or saline into the laryngeal vestibule via a chronic, transcutaneous supraglottal catheter. Overall, RL led to a significantly greater respiratory inhibition compared with the control group during LCR, including longer apnea duration (P = 0.01), lower minimal respiratory rate (P = 0.002), and a more prominent decrease in arterial hemoglobin saturation (SpO(2)) (P = 0.03). No effects were observed on cardiac variables. In conclusion, 1) our unique neonatal ovine model presents clinical and histological characteristics of RL; and 2) the presence of RL in newborn lambs increases the respiratory inhibition observed with LCR, at times leading to severe apneas and desaturations.

Our laboratory previously reported that active glottal closure was present in 90% of spontaneous central apneas in premature lambs while maintaining a high-apneic lung volume (Renolleau S, Letourneau P, Niyonsenga T, and Praud JP. Am J Respir Crit Care Med 159: 1396-1404, 1999.) The present study aimed at testing whether this mechanism limits postapnea oxygen desaturation. Four premature lambs were instrumented for recording states of alertness, thyroarytenoid muscle and diaphragm electromyographic (EMG) activity, nasal airflow, lung volume changes, and pulse oximetry. One thousand four hundred fifty-two spontaneous central apneas (isolated or during periodic breathing) were analyzed in nonsedated lambs. Apneas, with high lung volume maintained by active glottal closure, were compared with apneas, with a tracheostomy opened at apnea onset. Oxygen desaturation slopes were lower when high-apneic lung volume was actively maintained during both wakefulness and quiet sleep. Furthermore, oxygen desaturation slopes were lower after isolated apneas with continuous thyroarytenoid EMG during wakefulness, compared with apneas with noncontinuous thyroarytenoid EMG (= glottis opened shortly after apnea onset). These results highlight the importance of maintaining high-alveolar oxygen stores during central apneas by active glottal closure to limit desaturation in newborns.