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Biomedical subjects

William Rosenblatt

Publications and source records attributed to William Rosenblatt.

4 recordsLinked to original sources
PubMed2006

Effects of altered consciousness on the protective glottic closure reflex.

OBJECTIVES: The sphincteric function of the larynx, essential to lower airway protection, is most efficiently achieved through strong reflex adduction by both vocal folds. We hypothesize that central facilitation is an essential component of a bilateral brain stem-mediated adductor reflex and that its disturbance by altered consciousness or physiologic sleep could result in weakened sphincteric closure. METHODS: In 10 adult pigs the glottic closure response was evaluated under light and deep isoflurane anesthesia. The internal branch of the left superior laryngeal nerve was stimulated through bipolar platinum-iridium electrodes, and recording electrodes were positioned in the ipsilateral and contralateral thyroarytenoid muscles. The force of evoked glottic closure was measured with a pressure transducer positioned between the vocal folds. RESULTS: Consistent threshold responses (>90%) were obtained ipsilaterally from 0.5 to 2.0 minimal alveolar concentration (MAC) anesthesia. However, the contralateral reflex responses declined to 6.4% in successive trials as anesthetic levels approached 1.5 to 2.0 MAC. Furthermore, glottic closing force closely reflected these electromyographic changes, declining from 383 mm Hg at 0.5 to 1.0 MAC to 114 mm Hg at 1.5 to 2.0 MAC. CONCLUSIONS: Alteration of central facilitation by progressively deeper loss of consciousness abolishes a lower brain stem-mediated crossed adductor reflex, predisposing the subject to a weakened glottic closure response.

Anesthesia, Inhalation↗
PubMed2003

Central facilitation of the glottic closure reflex in humans.

The sphincteric function of the larynx, essential to lower airway protection, is most efficiently achieved through strong reflex adduction by both vocal cords. We hypothesize that central facilitation is an essential component of a bilateral adductor reflex and that its disturbance could result in weakened sphincteric closure. Five patients during supraglottic laryngectomy underwent evoked response laryngeal electromyography under 0.5 and 1.0 minimal alveolar concentration (MAC) isoflurane anesthesia. The internal branch of the superior laryngeal nerve was stimulated through bipolar platinum-iridium electrodes, and recording electrodes were positioned in the ipsilateral and contralateral thyroarytenoid muscles. Consistent threshold responses were obtained ipsilaterally from 0.5 to 1.0 MAC anesthesia. However, the contralateral reflex responses approached 0% in successive trials as anesthetic levels approached 1.0 MAC. In human subjects, alteration of central facilitation by deepening anesthesia abolishes the crossed adductor reflex, predisposing to a weakened glottic closure response. A precise understanding of this effect may improve the prevention of aspiration in patients emerging from prolonged sedation or under heavy psychotropic control.

Aged↗
PubMed2002

A multicenter study comparing the ProSeal and Classic laryngeal mask airway in anesthetized, nonparalyzed patients.

BACKGROUND: The laryngeal mask airway ProSeal (PLMA), a new laryngeal mask device, was compared with the laryngeal mask airway Classic (LMA) with respect to: (1) insertion success rates and times; (2) efficacy of seal; (3) fiberoptically determined anatomic position; (4) orogastric tube insertion success rates and times; (5) total intraoperative complications; and (6) postoperative sore throat in nonparalyzed adult patients undergoing general anesthesia, hypothesizing that these would be different. METHODS: Three hundred eighty-four nonparalyzed anesthetized adult patients (American Society of Anesthesiologists physical status I-II) were randomly allocated to the PLMA or LMA for airway management. In addition, 50% of patients were randomized for orogastric tube placement. Unblinded observers collected intraoperative data, and blinded observers collected postoperative data. RESULTS: First-attempt insertion success rates (91 vs. 82%, P = 0.015) were higher for the LMA, but after three attempts success rates were similar (LMA, 100%; PLMA, 98%). Less time was required to achieve an effective airway with the LMA (31 +/- 30 vs. 41 +/- 49 s; P = 0.02). The PLMA formed a more effective seal (27 +/- 7 vs. 22 +/- 6 cm H2O; P < 0.0001). Fiberoptically determined anatomic position was better with the LMA (P < 0.0001). Orogastric tube insertion was more successful after two attempts (88 vs. 55%; P < 0.0001) and quicker (22 +/- 18 vs. 38 +/- 56 s) with the PLMA. During maintenance, the PLMA failed twice (leak, stridor) and the LMA failed once (laryngospasm). Total intraoperative complications were similar for both groups. The incidence of postoperative sore throat was similar. CONCLUSION: In anesthetized, nonparalyzed patients, the LMA is easier and quicker to insert, but the PLMA forms a better seal and facilitates easier and quicker orogastric tube placement. The incidence of total intraoperative complications and postoperative sore throat are similar.

Adolescent↗