Jeffrey S. Katz

Difficult airway management practice patterns among anesthesiologists practicing in the United States: have we made any progress?

STUDY OBJECTIVE To determine the extent instruction and practice in the use of airway devices and techniques varies among anesthesiologists practicing in the United States. DESIGN Survey questionnaire. SETTING University medical center. MEASUREMENTS Questionnaires were completed by American-trained anesthesiologists who attended the 1999 American Society of Anesthesiologists (ASA) Annual Meeting. Data collected included demographics, education, skills with airway devices/techniques, management of clinical difficult airway scenarios, and the use of the ASA Difficult Airway Algorithm. MAIN RESULTS 1) DEMOGRAPHICS: 452 questionnaires were correctly completed; 62% attending anesthesiologists, 70% <50 years, 81% males, 44% from academic institutions, 63% >10 years of practice, 81% night duty, 77% board certified. 2) Education: 71% had at least one educational modality: difficult airway rotation, workshops, conferences, books, and simulators. 3) Skills: Miller blade 61%, Bullard laryngoscope 32%, LMA 86%, Combitube 43%, bougie 43%, exchangers 47%, cuffed oropharyngeal airway (COPA) 34%, retrograde 41%, transtracheal needle jet ventilation 34%, cricothyrotomy 21%, fiberoptics 59%, and blind nasal intubation 78%. The average reported use of special airway devices/techniques was 47.5%. 4) Management choices: failed intubation/ventilation: LMA (81%) and for all other situations: fiberoptic intubation. Use of ASA Difficult Airway Algorithm in clinical practice (86%). CONCLUSION Fiberoptic intubation and the LMA are most popular in management of the difficult airway.

Mechanisms of Same/Different Abstract-Concept Learning by Rhesus Monkeys (Macaca mulatta)

Experiments with 9 rhesus monkeys (Macaca mulatta) showed, for the first time, that abstract-concept learning varied with the training stimulus set size. In a same/different task, monkeys required to touch a top picture before choosing a bottom picture (same) or white rectangle (different) learned rapidly. Monkeys not required to touch the top picture or presented with the top picture for a fixed time learned slowly or not at all. No abstract-concept learning occurred after 8-item training but progressively improved with larger set sizes and was complete following 128-item training. A control monkey with a constant 8-item set ruled out repeated training and testing. Contrary to the unique-species account, it is argued that different species have quantitative, not qualitative, differences in abstract-concept learning.

Mechanisms of same/different concept learning in primates and avians

Mechanisms of same/different concept learning by rhesus monkeys, capuchin monkeys, and pigeons were studied in terms of how these species learned the task (e.g., item-specific learning versus relational learning) and how rapidly they learned the abstract concept, as the training set size was doubled. They had similar displays, training stimuli, test stimuli, and contingencies. The monkey species learned the abstract concept at similar rates and more rapidly than pigeons, thus showing a quantitative difference across species. All species eventually showed full concept learning (novel-stimulus transfer equivalent to baseline: 128-item set size for monkeys; 256-item set for pigeons), thus showing a qualitative similarity across species. Issues of stimulus regularity/symmetry, generalization from item pairs, and familiarity processing were not considered to be major factors in the final performances, converging on the conclusion that these species were increasingly controlled by the sample-test relationship (i.e., relational processing) leading to full abstract-concept learning.

Same/different abstract-concept learning by pigeons.

Eight pigeons were trained and tested in a simultaneous same/different task. After pecking an upper picture, they pecked a lower picture to indicate same or a white rectangle to indicate different. Increases in the training set size from 8 to 1,024 items produced improved transfer from 51.3% to 84.6%. This is the first evidence that pigeons can perform a two-item same/different task as accurately with novel items as training items and both above 80% correct. Fixed-set control groups ruled out training time or transfer testing as producing the high level of abstract-concept learning. Comparisons with similar experiments with rhesus and capuchin monkeys showed that the ability to learn the same/different abstract concept was similar but that pigeons require more training exemplars.

The Incidence of Class “zero” Airway and the Impact of Mallampati Score, Age, Sex, and Body Mass Index on Prediction of Laryngoscopy Grade

IMPLICATIONS In an earlier study we proposed the addition of a new airway class, zero (visualization of the epiglottis), to the four classes of the modified Mallampati classification. In this prospective study, 764 surgical patients were assessed with regard to their airway class (including class zero), laryngoscopy grade, and the effect of the airway class and other predictors on the laryngoscopy grade.

Anaesthesia for the achondroplastic dwarf

Abstract MissingOver the past three years, 36 anaesthetics were administered to 27 patients with achondroplastic dwarfism. Twenty-four patients underwent craniectomy for foramen magnum stenosis. Sixteen of the operations were undertaken in the sitting position with nine incidents of venous air embolism (VAE), all of which occurred in patients under 12 years of age.Six major complications occurred: two C-1 level spinal cord infarctions, two brachial plexus palsies, one severe macroglossia, and one accidental extubation.Intravenous access in the small child with achondroplastic dwarfism is made difficult because of the excess, lax skin and subcutaneous tissue.Airway management and laryngoscopy were not difficult and we found that endotracheal tube size was best predicted by the patients weight and not age.Blood loss was 38±9 mg·kg−1 in the prone position (n = 8) and 18±4 mg·kg−1 in the sitting position (n = 16), and was related to the surgical procedure rather than to dwarfism.Our data indicate that complications are more likely to occur in the sitting position, and that these complications are of a serious nature, and every precaution should be taken to avoid their occurrence.RésuméAu cours de trois dernières années, 36 anesthésies ont été administrées à 27 patients atteint nanisme achondro-plasique. Vingt quatre patients ont subi une crdniectomie pour sténose du foramen occipital. Seize de ces opérations ont été accomplies dans une position assise avec neuf incidents d’embolies gazeuse, tous survenant chez des patients dgés de moins de 12 ans.Six complications majeures sont survenues: deux infarcisment de la moelle épinière au niveau de C-1, deux plexus brachial, une macroglossie sévère, et une extuba-tion accidentelle.L’accès intraveineux du patient avec un nanisme achondroplasique est difficile é cause de I’excès de peau et de tissus sous-cutané.La conduite de maintien des voies aériennes et la laryngoscopie riétaient pas difficile et on a trouvé que la grosseur du tube endotrachéal est mieux prédite par le poids du patient plûtot que son ôge. Les pertes sanguines ont été de 38 ± 9ml.kg-1 en position couchie (n = 8) et 18 ±4 ml.kg-1 en position assise (n = 16), et était en relation avec la position chirurgicale plutôt qu’au nanisme. Nos données indiquent que les complications surviennent plus fréquemment en position assise celles ci sont dangeureuses et toutes les précautions doivent étre prises afin d’éviter leur survenue.

Changes in onset time of rocuronium in patients pretreated with ephedrine and esmolol - The role of cardiac output

Background:  We investigated the hypothesis that manipulation of cardiac output (CO) with esmolol (Es) or ephedrine (E) affects the onset time of rocuronium.

The onset time of rocuronium is slowed by esmolol and accelerated by ephedrine.

Administration of ephedrine prior to rocuronium decreases the onset time of neuromuscular blockade from rocuronium by 26%. This effect was attributed to a increased cardiac output. If so, &bgr; adrenergic-blocking drugs, which decrease cardiac output, should prolong the onset time of rocuronium. In a double-blind study, 60 patients were randomly assigned to three groups (n = 20) to receive either 70 &mgr;g · kg−1 of ephedrine, 0.5 mg · kg−1 esmolol or placebo, 30 s before induction of anesthesia. Onset time of rocuronium was defined as the time from the end of its injection to disappearance of all four twitches of the train-of-four. The onset time of rocuronium was significantly shorter after ephedrine (22%) and longer after esmolol (26%), as compared to placebo. No differences were observed among the three groups with regard to heart rate, systolic, diastolic or mean blood pressure. We concluded that a dose of 0.5 mg · kg−1 of esmolol significantly prolongs the onset time of rocuronium with minimal hemodynamic changes. Implications We concluded that a dose of 0.5 mg · kg−1 of esmolol significantly prolongs the onset time of rocuronium with minimal hemodynamic changes.

Difficult airway in obstetric anesthesia: a review.

Failed intubation and ventilation are important causes of anesthetic-related maternal mortality. The purpose of this article is to review the complex issues in managing the difficult airway in obstetric patients. The importance of prompt and competent decision making in managing difficult airways, as well as a need for appropriate equipment is emphasized. Four case reports reinforce the importance of a systematic approach to management. The overall preference for regional rather than general anesthesia is strongly encouraged. The review also emphasizes the need for professional and experienced team cooperation between the obstetrician and the anesthesiologist for the successful management of these challenging cases. Target Audience: Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader will be able to break down the complex issues in managing the difficult airway in the obstetric patient, outline the reasons for difficult intubations in pregnancy, and describe the evaluation used to predict a difficult intubation.

Combined spinal-epidural anesthesia for Cesarean section in a patient with peripartum dilated cardiomyopathy.

A combined spinal epidural anesthesia was performed and 6 mg of bupivacaine were injected into the subarachnoid space. This was supplemented after 60 min with 25 mg of bupivacaine injected epidurally. The patient’s hemodynamic status was monitored with direct intra-arterial blood pressure and central venous pressure measurements. The patient’s perioperative course was uneventful. Conclusion: In patients suffering from peripartum cardiomyopathy, undergoing Cesarean section, combined spinal-epidural anesthesia may be an acceptable anesthetic alternative.PurposeTo report a case of peripartum dilated cardiomyopathy associated with morbid obesity and possible difficult airway presenting for elective Cesarean section, which was successfully managed with combined spinal-epidural anesthesia.Clinical featuresA morbidly obese parturient with a potentially difficult airway, suffering from idiopathic peripartum cardiomyopathy (ejection fraction 20%), was scheduled for an elective Cesarean section.RésuméObjectifPrésenter un cas de cardiomyopathie du péripartum associée à de ïobésité morbide et à des difficuités d’intubation possibles chez une patiente qui a subi une césarienne réalisée avec succès sous anesthésie rachidienne et périduraie combinée.Eléments cliniquesUne parturiente, présentant une obésité morbide et des difficuités d’intubation possibies, souffrait de cardiomyopathie idiopathique du péripartum (fraction d’éjection de 20%) au moment de subir ia césarienne prévue.L’anesthésie rachidienne et périduraie combinée a été réaiisée avec l’injection de 6 mg de bupivacaine dans l’espace sousarachnoïdien, complétée après 60 min, par l’injection périduraie de 25 mg de bupivacaïne. L’état hémodynamique de ia patiente a été surveiiié par des mesures directes de ia tension intraartérielle et de ia pression veineuse centraie. Aucun incident périopératoire n’a été observé.ConclusionL’anesthésie rachidienne et périduraie combinée peut être un choix acceptable à envisager dans le cas de patientes atteintes de cardiomyopathie du péripartum qui subissent une césarienne.