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Biomedical subjects

Jonathan L Benumof

Publications and source records attributed to Jonathan L Benumof.

At least 19 recordsLinked to original sources
PubMed2005

The esophageal-tracheal combitube resistance and ventilatory pressures.

STUDY OBJECTIVE: To measure resistance of the Combitube, a supraglottic ventilatory device used in the management of the patients with difficult airways, and its influence on delivered ventilatory pressures. DESIGN: Prospective study. SETTING: University-affiliated hospital. PATIENTS: A total of 20 patients with ASA status I or II who were scheduled for elective knee arthroscopy. INTERVENTIONS: (Part 2 of the study) After induction of general anesthesia and insertion of the Combitube, mechanical ventilation was initiated. Airway pressures were measured using fluid-filled pressure lines at the Y-piece (P(Y-piece)) of the breathing system and in the oropharynx (P(oropharynx)) at a position 2 cm beyond the second proximal anterior hole of the Combitube. These pressures were simultaneously recorded and the pressure curves were compared. MEASUREMENTS: (Part 1 of the study) Resistance of the esophageal and the tracheal lumen of the 37-F Combitube and standard endotracheal tubes (with internal diameters of 6, 7, and 8 mm) was compared ex vivo with a Datex AS/3 monitor. Ventilation conditions were kept constant at a tidal volume of 0.5 L, frequency of 10 breaths per minute, and ramp flow waveform and peak flow of 1 L/s. MAIN RESULTS: Resistance of standard endotracheal tubes was inversely proportional to their diameters (16, 11, and 7 cm H(2)O/L per second for the tubes with internal diameters of 6, 7, and 8 mm, respectively). The resistance of the Combitube's tracheal lumen was 12 cm H(2)O/L per second. There was a significant difference in peak respiratory pressures between P(Y-piece) and P(oropharynx) (40 +/- 5 and 23 +/- 5 cm H(2)O, respectively). CONCLUSIONS: The Combitube has significant airflow resistance that should be considered when patients are mechanically ventilated because the delivered oropharyngeal pressure is significantly lower than the pressure measured at the anesthesia breathing system.

Adult↗
PubMed2004

Pressure on the face while in the prone position: ProneView versus Prone Positioner.

STUDY OBJECTIVE: To measure the surface pressure on the face of a patient placed in the prone position with the most commonly used prone positioning devices, a non-face-contoured positioner (PP) and a new face-contoured device (PV). DESIGN: Prospective, randomized comparison. SETTING: Operating room in an American academic medical center. SUBJECTS: 35 randomly recruited adult volunteers. INTERVENTIONS: Surface pressure on the face was measured in awake subjects placed in the prone position, with the head and neck in the position of most comfort, using both the PP and PV devices. MEASUREMENTS: Surface pressure was obtained using an array of small transducers imbedded in a thin cushion that was interfaced between the face and positioning device. The amount of extension or flexion of the head on the neck was estimated using an angular measurement of eye-ear line and horizontal line. MAIN RESULTS: The average surface pressure on the face was less with the PV than with the PP (21 +/- 3 mmHg vs. 27 +/- 5 mmHg; p < 0.0001). The number of areas where pressure exceeded 30 mmHg and 50 mmHg was lower for the PV than the PP (15 +/- 7.5 areas vs. 19 +/- 7.2 areas > 30 mmHg; p < 0.05; 5.2 +/- 3.3 areas vs. 9.0 +/- 5.0 areas > 50 mmHg; p < 0.0001). Pressure on the chin increased with extension of the head or neck (p < 0.05) with both devices. CONCLUSIONS: Surface pressure on the face in the prone position is 29% higher with the non-face-contoured PP than with the face-contoured PV. The number of areas on the face where the surface pressure is greater than 50 mmHg is 80% higher with the PP than the PV. Small degrees of head extension increases pressure on the chin. Both devices produce areas of pressure, typically over the chin, which may be associated with local skin damage. Keeping the head and neck in a non-flexed, non-extended position may minimize pressures.

Equipment Design↗
PubMed2003

Airway problems and new solutions for the obstetric patient.

Anesthesia-related complications are the sixth leading cause of pregnancy-related maternal mortality in the United States. Difficult or failed intubation following induction of general anesthesia for cesarean delivery remains the major contributory factor to anesthesia-related maternal complications. Although the use of general anesthesia has been declining in obstetric patients, it may still be required in selected cases. Because difficult intubation in obstetric anesthesia practice is frequently unexpected, careful and timely preanesthetic evaluation of all parturients should identify the majority of patients with difficult airway and avoid unexpected difficult airway management.

Adult↗
PubMed2003

An initially unnoticed piece of nasal jewelry in a parturient: implications for intraoperative airway management.

The literature documenting the anesthetic implications of body piercing consists only of a few case reports that focus exclusively on interference with airway management by oral jewelry. To date, no case reports documenting anesthetic problems resulting from the presence of nasal jewelry have been reported. We present a case of a parturient who presented for an emergency cesarean section with nasal jewelry in situ, which was unnoticed preoperatively and then became externally loosened intraoperatively. This situation necessitated fiberoptic examination of the nasopharyngeal and oropharyngeal cavities and radiologic imaging studies to rule out aerodigestive tract aspiration of retained and missing piece(s) of the jewelry. Based on this experience, we now advise all laboring parturients with nasal or oral jewelry in situ to remove the hardware on admission to Labor and Delivery for safety precautions.

Adolescent↗
PubMed2003

Rebound hyperkalemia after cessation of intravenous tocolytic therapy with terbutaline in the treatment of preterm labor: anesthetic implications.

Beta-adrenergic agents have been widely used in obstetrics to attenuate premature labor (termed tocolytic therapy), delay delivery, allow fetal maturation, and thereby reduce neonatal morbidity and mortality. Hypokalemia is a common side effect during beta-adrenergic tocolytic therapy for the treatment of preterm labor. Although rebound hyperkalemia after cessation of tocolytic therapy with ritodrine has been reported, there have been no reports of hyperkalemia occurring after the cessation of beta-adrenergic tocolytic therapy with terbutaline for preterm labor; we report such a case.

Adult↗
PubMed2002

Obstructive sleep apnea in the adult obese patient: implications for airway management.

Adult obese patients with suspected or sleep test confirmed OSA present a formidable challenge throughout the perioperative period. Life-threatening problems can arise with respect to tracheal intubation, tracheal extubation, and providing satisfactory postoperative analgesia. Tracheal intubation and extubation decisions in obese patients with either a presumptive and/or sleep study diagnosis of OSA must be made within the context that there may be excess pharyngeal tissue that cannot be visualized by routine examination, and the literature indicates an increased risk of intubation difficulty. Regional anesthesia for postoperative pain control is desirable (although such management is not necessary or possible for many of these patients). If opioids are used for the extubated postoperative patient, then one must keep in mind an increased risk of pharyngeal collapse and consider the need for continuous visual and electronic monitoring. The exact management of each sleep apnea patient with regard to intubation, extubation, and pain control requires judgment and is a function of many anesthesia, medical, and surgical considerations.

Anesthesia↗
PubMed2002

Current status of the Combitube: a review of the literature.

The Combitube (Tyco-Healthcare-Kendall-Sheridan, Mansfield, MA) is an easily inserted and highly efficacious device to be used as an alternative airway whenever conventional ventilation fails. The Combitube allows ventilation and oxygenation whether the device locates in the esophagus (very common) or the trachea (rare). In this report, we review studies that suggest the Combitube is a valuable and effective airway in the emergency and prehospital settings, in cardiopulmonary resuscitation, in elective surgery, and in critically ill patients in the intensive care unit. Also reviewed are studies that demonstrate the superiority of the Combitube over other supraglottic ventilatory devices in resuscitation with respect to success rates with insertion and ventilation. Contrary to the Laryngeal Mask Airway, the Combitube may help in patients with limited mouth opening. The Combitube may be of special benefit in patients with massive bleeding or regurgitation, and it minimizes the risk of aspiration.

Emergencies↗
PubMed2002

Tongue piercing and obstetric anesthesia: is there cause for concern?

The practice of oral tissue piercing, until recently, has been limited mainly to various native tribes in Africa. However, in recent years, body piercing (including oral tissue piercing), has become increasingly popular in the United States and Europe. We present a case of an obstetric patient who presented for emergency postpartum surgery with fixated tongue jewelry in situ, which resulted in trauma to the tongue and difficult airway management. The difficult airway management consisted of tongue bleeding at the time of laryngoscopy and tongue edema at extubation. We consider these two events to be near misses of "cannot intubate" and "cannot ventilate" situations, respectively. Because the popularity of body piercing is increasing in our society, it is reasonable to expect that the incidence of oral jewelry interference with airway management will also increase. Based on this experience, we advise laboring patients with oral jewelry to remove the hardware before receiving anesthesia for safety reasons.

Adult↗