Insertion of the endotracheal tube, laryngeal mask airway and oesophageal-tracheal Combitube. A 6-month comparative prospective study of acquisition and retention skills by medical students.

OBJECTIVE: To assess the ability of medical students to learn and retain skills of airway manipulation for insertion of the endotracheal tube, the laryngeal mask airway (Laryngeal Mask Company, Henley-on-Thames, UK) and the oesophageal-tracheal Combitube (Kendall-Sheridan Catheter Corp., Argyle, NY, USA). METHODS: A 6-month prospective study was conducted among fifth-year medical students attending a 3-week clerkship in the Division of Anesthesiology and Critical Care Medicine in the Soroka Medical Center. All the students viewed a demonstration of insertion technique for the endotracheal tube, the laryngeal mask airway and the Combitube, followed by formal teaching in a mannikin. At the end of the program, the insertion skills were demonstrated in the mannikin, the success rate on the first attempt was registered and the students were requested to assess (by questionnaire) their ability to execute airway manipulation (phase 1). Six months later, the students were requested to repeat the insertion technique, and a similar re-evaluation applied (phase 2). RESULTS: The success rate, during the first phase, at first attempts was 100% for the laryngeal mask airway and the Combitube, compared to 57.4% for the endotracheal tube (P < 0.02), and 92.6%, 96.2% and 62.9% (P < 0.02) respectively for the second phase of the study. CONCLUSION: Learning and retention skills of medical students, in a mannikin, are more accentuated with the laryngeal mask airway and the Combitube than seen with an endotracheal tube.

Should disclosure of the danger of awareness during general anesthesia be a part of preanesthesia consent?

Awareness during anesthesia (AGA) is known as an intraoperative incident which could lead to a series of untoward effects, among them symptoms compatible with the posttraumatic stress syndrome (PTSS). Incidence of AGA ranges between 0.1% and 0.7%, most of the reports indicating a 0.2% rate of all general anesthesias. Nevertheless, some patients are considered to be in a higher than usual risk for developing this incident. The list of AGA high-risk situations include caesarian section, open heart surgical procedures, marked obesity, major trauma with hemodynamic instability and chronic use of drugs, alcohol or tobacco smoking. The usual preanesthetic informed consent does not mention AGA among the possible undesired effects of general anesthesia, neither in Israel nor in other parts of the world. This paper rises the question of the indication to discuss the AGA matter, as part of the informed consent, with any patient who is prone develop it in a significant higher percentage than the general population. The topic can be discussed by the primary care physician or by the surgeon, but this represents the obvious task of the anesthesiologist during his/her first contact with the patient before anesthesia and surgery. It is the authors belief that a preoperative discussion on AGA might substantially reduce the magnitude of repercussions of AGA among high-risk patients to develop this anesthetic complication.

Vocal cord paralysis as a consequence of peritonsillar infiltration with bupivacaine.

Reduction of postoperative pain is an important goal in the perioperative management of tonsillectomy patients. This is particularly the case for children, who often exhibit resistance to intramuscular or rectal administration of drugs. Peritonsillar bupivacaine infiltration, a relatively safe method of pain control, is in some centers frequently used by otolaryngologists for pain relief. We present the case of a 5-year-old girl who developed bilateral vocal cord paralysis following preoperative peritonsillar bupivacaine infiltration. After an uneventful tonsillectomy and extubation, stridor and respiratory distress developed. Bilateral vocal cord paralysis was seen on laryngoscopy. The patient was reintubated and five hours later was successfully extubated without further sequelae. Anesthesiologists and surgeons should be aware of this uncommon complication than can occur with the use of peritonsillar bupivacaine infiltration for pain control in tonsil surgery.

Can pediatric anesthesiologists detect an occluded tracheal tube in neonates?

UNLABELLED: To determine whether pediatric anesthesiologists can reliably detect occluded tracheal tubes, 18 pediatric anesthesiologists who were blindfolded and fitted with earplugs manually ventilated the lungs of 16 neonates. Consent was obtained from the parents of the neonates. All auditory signals from the monitors were silenced. Six conditions were studied (for 3 min each) in random order: three models of Ayre's t-piece with the Jackson Rees modification and two fresh gas flows (FGF) (2 and 6 L/min). During each condition, the tracheal tube was clamped at five predetermined but randomized times. The volume/pressure relationships of the three t-piece models were determined. Tube occlusions were detected more frequently at a low FGF (82%) than at a high FGF (64%) (P < 0.001). Experienced anesthesiologists (>8 yr experience) detected occlusions (83%) more frequently than less experienced (<2 yr experience) anesthesiologists (63%) (P < 0.027). There was no interaction between FGF and experience. The type of circuit did not affect the detection rate. We conclude that during isolated hand ventilation with the t-piece, pediatric anesthesiologists can detect >80% of occluded tubes provided they use a low FGF or have >8 yr experience, but only 60% of occluded tubes at high FGF or if they have <2 yr experience. IMPLICATIONS: Hand ventilation of the lungs in neonates has been used to detect changes in respiratory compliance, but laboratory models have failed to demonstrate its usefulness. We determined that pediatric anesthesiologists could detect 83% of tracheal tube occlusions in neonates if either the fresh gas flow was 2 L/minor the pediatric anesthesiologist was experienced (> 8 yr).

Use of EEG spectral edge as index of equipotency in a comparison of propofol and isoflurane for maintenance of general anaesthesia.

Propofol and isoflurane were compared for haemodynamic stability and recovery time as main anaesthetic agents for maintenance in a total of 43 ASA I and II patients in uncomplicated operations lasting at least 30 min. The premedication (oral diazepam), induction (thiopentone-fentanyl-suxamethonium) and maintenance protocol (N2O-O2 2:1 litre min-1, fentanyl and vecuronium in incremental doses) were identical for all patients. In one group of 20 patients, propofol was used in continuous intravenous (i.v.) infusion (starting dose 3 mg kg-1 h-1), while in the second group of 23 patients, isoflurane was administered in a starting concentration of 1%. To improve the equipotency of the two agents in all cases the dose of the main anaesthetic was titrated to keep the EEG 90% spectral edge frequency (SEF-recorded by processed EEG monitor) between 8 and 12 Hz. Mean blood pressure (BP) and heart rate (HR) deviations of +/- 20% from the baseline were recorded. The incidence of mean blood pressure deviations/case in the propofol group was less than half of those occurring in the isoflurane group (0.45 vs. 0.96 P = 0.04). The mean duration of blood pressure deviation from baseline value was 5.5 min in the propofol group vs. 16.8 min in the isoflurane group (P = 0.01). The recovery intervals were significantly shorter in the propofol group (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Event-related brain potentials (P300) and neuropsychological deficit in patients with focal brain lesions.

Sixteen patients with chronic focal brain lesions were investigated with an acoustic P300 test and psychological tests of spatial abilities (Maze Tracing Speed Test, Form Board Test), cognitive speed (Sequential Number Connection Test), categorization (Figure Sorting Test), verbal fluency and vigilance. Neither the psychological battery nor P300 analysis discriminated frontal from retrorolandic brain lesions. Abnormalities of P300 significantly correlated with impairments in those psychological tests which had a spinal component in common. We suggest that abnormality of the P300 with focal brain damage rather indicates higher mental function impairment than direct effects of the lesion.