James R. Boyce

A preliminary study of the optimal anesthesia positioning for the morbidly obese patient.

Background: Hypoxemia during the induction of general anesthesia for the morbidly obese patient is a major concern of anesthesiologists. The etiology of this pathophysiological problem is multifactorial, and patient positioning may be a contributing factor. The present study was designed to identify optimal patient positioning for the induction of general anesthesia that minimizes the risk of hypoxemia in these patients. Methods: 26 morbidly obese patients (body mass index - BMI 56±3) were randomly assigned to one of three positions for induction of anesthesia: 1) 30° Reverse Trendelenburg; 2) Supine-Horizontal; 3) 30° Back Up Fowler. Mask ventilation, full neuromuscular paralysis and direct laryngoscopy were performed. Any airway difficulties were noted. After endotracheal tube placement, subjects were ventilated for 5 minutes with 1% isoflurane in a mixture of 50% oxygen / 50% air and then disconnected from the ventilation circuit.The time required for capillary oxygen saturation (SaO2), as measured by pulse oximeter, to decline from 100% to 92% was noted and identified as the safe apnea period (SAP). Ventilation was then immediately re-established.The lowest SaO2 after resuming ventilation and the time from that nadir to an SaO2 of 97% were also recorded. Results: BMI and hip-waist ratios of patients in groups 1, 2 and 3 did not significantly differ. There were no differences in airway difficulties between the different groups. The SAP in groups 1, 2 and 3 was 178±55, 123±24 and 153±63 seconds, respectively. The SaO2 of patients in the reverse Trendelenburg position dropped the least and took the shortest time to recover to 97%. Conclusions: In morbidly obese patients, the 30° Reverse Trendelenburg position provided the longest SAP when compared to the 30° Back Up Fowler and Horizontal-Supine positions. Since on induction of general anesthesia morbidly obese patients may be difficult to mask ventilate and/or intubate, this extra time may preclude adverse sequelae resulting from hypoxemia. Therefore, Reverse Trendelenburg is recommended as the optimal position for induction.

Vessel dilator cricothyrotomy for transtracheal jet ventilation

Needle cricothyrotomy is a safe, relatively easy procedure and has been described to enable pulmonary ventilation for patients in both elective and emergency situations. Conventional IV cannulae are short, thinwalled, and easily kinked and, therefore, do not provide a secure system to jet oxygen into the trachea. The vessel dilators of most 7– 9 French introducer kits are firm, pliable, resist kinking, and can be passed easily into the tracheal lumen. We describe our experience with the use of vessel dilator cricothyrotomy to oxygenate and ventilate the lungs of patients in emergency and elective situations.RésuméLa cricothyrotomie à l’aiguille est une technique súre et relativement facile mais les catheters IV souvent utilisés ont une paroi mince qui peut s’affaisser, empêchant l’utilisation d’un système à injection d’oxygène. Les dilatateurs vasculaires des ensembles d’introducteur 7–9 French sont souples mais résistants et on peut les glisser facilement dans la trachée. Nous les avons utilisés pour l’oxygénation et la ventilation pulmonaire de nombreux patients, y compris en situations d’urgence.

Preemptive vessel dilator cricothyrotomy aids in the management of upper airway obstruction

PurposeOur objective was to demonstrate that preemptive vessel dilator cricothyrotomy may be useful when managing the patient with airway obstruction.MethodsAn Institutional Review Board approved retrospective study was undertaken in 88 patients for whom this technique was selected. The anesthesiologists and surgeons identified as authors were directly involved in the care of these patients. All vessel dilator cricothyrotomies were performed in the operating rooms of University Hospital, UAB, Medical Center. The patients selected for this airway management technique were afflicted with some type of supraglottic lesion, usually squamous cell carcinoma, which was obstructing their airways to an extent that complete airway obstruction during induction of anesthesia was a significant possibility.Prior to induction of anesthesia, the vessel dilator was inserted into the tracheal lumen through the cricothyroid membrane as described. Oxygenation was maintained with jet ventilation from a Sanders jetting device. Age, sex, weight, initial and lowest O2 saturation, first recorded ETCO2, blood pressure and duration of jet ventilation were recorded.ResultsThe airways were successfully managed in all 88 patients with this technique. There were no deaths, and no postoperative hypoxic sequelae; also complications were minor.ConclusionVessel dilator cricothyrotomy as a preemptive procedure in the management of patients with significant supraglottic airway obstruction may be a useful addition to the anesthesiologists’ armamentarium of airway management devices.RésuméObjectifDémontrer que la crico-thyrotomie préventive avec un dilatateur vasculaire peut aider la prise en charge ďune obstruction des voies respiratoires.MéthodeLe comité ďexamen a approuvé notre étude rétrospective auprès de 88 patients soumis à cette technique. Les anesthésiologistes et les chirurgiens, auteurs du présent article, ont été directement appelés à participer. Toutes les crico-thyrotomies avec dilatateur vasculaire ont été réalisées dans les salles ďopération du University Hospital, UAB, Medical Center. Les patients choisis présentaient une lésion oropharyngée, habituellement un épithéliome malpighien, qui obstruait les voies respiratoires de façon tellement étendue qu’une obstruction complète des voies aériennes était à craindre pendant ľinduction de ľanesthésie. Avant ľinduction, le dilatateur vasculaire a été inséré dans la lumière de la trachée par la membrane cricotyroïdienne. ľoxygénation a été maintenue avec la ventilation en jet par un appareil à jet Sanders. ľâge, le poids, la saturation initiale en O2 et la plus faible saturation, la première ETCO2 enregistrée, la tension artérielle et la durée de la ventilation en jet ont été notés.RésultatsLes voies aériennes ont été bien protégées chez tous les patients. Il n’y a pas eu de décès ni de séquelles hypoxiques postopératoires, seulement des complications mineures.ConclusionLa crico-thyrotomie avec dilatateur vasculaire, utilisée comme technique préventive chez des patients qui présentent une obstruction oropharyngée, peut s’ajouter avantageusement aux appareils de prise en charge des voies aériennes par les anesthésiologistes.

Continuous Infusion of Bupivacaine for Pain Control After Anterior Iliac Crest Bone Grafting for Alveolar Cleft Repair in Children

Objective The purpose of this study was (1) to evaluate the analgesic efficacy of continuous infusion bupivacaine, (2) to evaluate the effects of the site-specific catheter infusion on operating room time, narcotic use, ambulatory status, and length of hospitalization, (3) to monitor for adverse outcomes, and (4) to assess patient/family acceptance. Design Randomized, double-blinded, and prospective study of bupivacaine versus saline for pain control after anterior iliac crest bone grafting for alveolar cleft repair. Setting University of Alabama at Birmingham. Patients A total of 65 pediatric patients with alveolar cleft defects treated between 2006 and 2009. Interventions Anterior iliac crest bone grafting for alveolar cleft repair with assignment to either a bupivacaine or a saline infusion group. Main Outcome Measures Physical examination, pain ratings, narcotic use, ambulatory status, operating room time, and length of hospital stay. Results On the blinded physical exam, 71% in the bupivacaine infusion group and 42% in the saline infusion group were assessed as not experiencing pain at the surgical hip site. The experimental group used less narcotics compared with the control group. No significant differences were noted with operating room time, initial ambulatory status, or length of hospitalization (1.09 versus 1.12 days). Satisfaction and acceptance of the catheter treatment was universal. Conclusions These results suggest that postoperative infusion of bupivacaine may be efficacious for enhancing pain relief after bone harvest in pediatric patients and may enhance parental perceptions of postoperative care; however, this patient population is difficult to study accurately.

Effects of halothane on the pharmacokinetics of lidocaine in digitalis-toxic dogs

SummaryFollowing the production of digitalis toxicity in dogs as manifested by ventricular tachycardia, the pharmacokinetics of lidocaine treatment of the arrhythmia were determined during pentobarbitone anaesthesia and pentobarbitone-halo-thane anaesthesia. The elimination rate constants, β and Ke, and the biological half life T1/2p were statistically significantly increased during halothane anaesthesia. The volume of distribution was unchanged. The results indicate that the therapeutic loading dose of lidocaine need not be altered during halothane anaesthesia but if a constant infusion is used, the rate of infusion would have to be decreased four fold to avoid toxic plasma levels of lidocaine.RésuméAprès avoir provoqué chez le chien de la tachycardie ventriculaire par intoxication digitalique, les auteurs ont étudié la pharmacocynétique de la lidocaine lors du traitement de ľarythmie sous anesthésie au pentobarbital seul et à ľhalothane associé au pentobarbital. ľanalyse statistique a mis en évidence une augmentation significative de la vitesse ďexcrétion (constantes 0 et Ke) et de la demi-vie biologique (T1/23) pendant ľanesthésie à ľhalothane. Le volume de distribution n’a pas changé. ďaprès ces résultats, il ne semble pas nécessaire ďaugmenter la dose ďattaque de lidocaine sous anesthésie à ľhalothane. Toutefois, lors ďadministration continue, la perfusion devrait être ramenée au quart de sa vitesse habituelle pour éviter une augmentation de la concentration plasmatique jusqu’à des niveaux toxiques.

Poor man's LMA: achieving adequate ventilation with a poor mask seal.

PurposeThis report describes a technique of ventilation prior to laryngoscopy and intubation that proved to be simple, inexpensive and effective for a patient whose airway evaluation suggested difficult mask ventilation. The technique is called Poor Man’s LMA.Clinical featuresA 60-yr-old male, measuring 170 cm, weighing 117 kg, edentulous and with a full beard, was to undergo uvulopalatopharyngoplasty. After induction of general anesthesia with a hypnotic, analgesic and non-depolarizing muscle relaxant, it was soon determined that mask bag ventilation was difficult due to an inadequate seal between the mask and the patient’s full beard. To improve ventilation, an endotracheal tube was placed into the oropharynx, the lips and nose compressed by a colleague in order to prevent gas egress, and effective manual ventilation established by connecting the circle system to the endotracheal tube. Subsequent direct laryngoscopy and intubation were accomplished without incident.ConclusionThe patient’s clinical features made conventional mask bag ventilation difficult and inadequate. The Poor Man’s LMA technique improved oxygenation and ventilation in preparation for intubation. Further investigations on the usefulness of this technique are warranted.RésuméObjectifDécrire une technique de ventilation, utilisée avant la laryngoscope et l’intubation, qui s’est révélée simple, peu coûteuse et efficace chez un patient dont l’évaluation des voies aériennes laissait présager des difficultés de ventilation au masque. C’est la technique du ML improvisé.Éléments cliniquesUn homme de 60 ans, mesurant 170 cm, pesant 117 kg, édenté et portant sa barbe entière devait subir une uvulopalatopharyngoplastie. Après l’induction de l’anesthésie générale avec un hypnotique, un analgésique et un myorelaxant non dépolarisant, on s’est vite rendu compte que la ventilation au masque serait difficile étant donné le manque d’étanchéité entre le masque et la barbe du patient. Un tube endotrachéal a été introduit dans l’oropharynx, les lèvres et le nez ont été compressés par un collègue pour éviter toute fuite de gaz et la ventilation manuelle effective a été établie en raccordant le système circulaire au tube endotrachéal. Par la suite, la laryngoscope et l’intubation ont été réalisées sans incident.ConclusionLes caractéristiques cliniques du patient ont rendu difficile et incomplète la ventilation au masque traditionnelle. La technique du ML improvisé a permis d’améliorer l’oxygénation et la ventilation en vue de l’intubation. D’autres recherches sur l’utilité de cette technique sont donc à faire.

Transnasal jet ventilation is a useful adjunct to teach fibreoptic intubation: a preliminary report

PurposeFibreoptic intubation (FOI) has become an essential technique in the anesthetic management of patients with difficult airways. Unfortunately, residents may graduate from anesthesiology training programs with insufficient skills in FOI. To enhance resident proficiency at FOI without compromising patient comfort or safety, the technique of transnasal jet ventilation-assisted FOI was developed. This report describes our initial experience with this technique.MethodsSixty-four patients scheduled for oromaxillofacial surgery under nasal endotracheal anesthesia were recruited. Twenty-eight residents at all levels of training performed FOI through the patient’s right nostril after the induction of general anesthesia and neuromuscular blockade. Oxygenation and ventilation were maintained by a faculty anesthesiologist using a Sanders device to deliver a jet of oxygen through a nasal trumpet placed in the patient’s left nostril. The time from induction until completion of the FOI was recorded. Residents were subsequently queried about the educational benefit of the technique using a standardized questionnaire.ResultsAll residents were able to successfully intubate all patients in this study. Thirteen residents successfully performed intubations on three or more occasions with 70% performing the technique faster on the third trial than on the first. No evidence of hypoxemia, gastric distension, pneumothorax, hemodynamic instability or recall was observed. All respondents to the questionnaire reported that the technique was useful as an educational tool and recommended its use with other residents.ConclusionTransnasal jet ventilation-assisted FOI is a useful method to train residents in FOI while maximizing patient comfort and safety.RésuméObjectifLintubation fibroscopique (IF) est devenue une technique anesthésique essentielle en cas de problèmes d’intubation. Malheureusement, des résidents peuvent devenir anesthésiologistes sans avoir les habiletés nécessaires à l’IF. Pour améliorer leur compétence en IF sans compromettre le confort et la sécurité des patients, la technique d’IF assistée de la ventilation en jet transnasale a été mise au point. Nous décrivons notre première expérience avec cette technique.MéthodeNous avons recruté 64 patients devant subir une opération oro-maxillo-faciale sous anesthésie endotrachéale nasale. Vingthuit résidents de tous les niveaux de formation ont réalisé une IF utilisant la narine droite du patient, après l’induction de l’anesthésie générale et le bloc neuromusculaire. L’oxygénation et la ventilation ont été maintenues par un anesthésiologiste à l’aide d’un appareil Sanders qui distribue un jet d’oxygène au travers d’une canule nasale placée dans la narine gauche du patient. Le temps écoulé entre l’induction de l’anesthésie et la fin de l’IF a été noté. Les résidents ont répondu ensuite à un questionnaire normalisé sur les avantages éducatifs de la technique.RésultatsTous les résidents ont réussi à intuber tous les patients de l’étude. Treize résidents ont réussi des intubations en trois occasions ou plus; 10 % d’entre eux ont réalisé la technique plus vite au troisième essai qu’au premier. Aucune évidence d’hypoxémie, de distension gastrique, de pneumothorax, d’instabilité hémodynamique ou de prise de conscience n’a été observée. Tous les répondants au questionnaire ont reconnu que la technique était utile à la formation et ont recommandé son usage par les autres résidents.ConclusionL’IF assistée de ventilation en jet transnasale est une méthode de formation utile des résidents et maximise le confort et la sécurité du patient.

Effectiveness of transnasal jet ventilation - a teaching aid.

To the Editor: We have developed a technique of transnasal jet ventilation to facilitate resident education in the area of fiberoptic intubation. The patients selected are scheduled for oromaxillofacial surgical procedures with a nasal endotracheal tube. This technique is used only in patients in whom the airway evaluation (oropharyngeal classification, head extension, and hyomental distance) predicts easy intubation, and are free of pathology that is obstructive or potentially obstructive to the airway. After preoxygenation and application of appropriate monitors, selected patients undergo induction of general anesthesia with sodium thiopental, 3–5 mg·kg– 1, fentanyl 3–4 μg·kg– 1 and rocuronium 0.6 mg·kg– 1. Lidocaine 1.5 mg·kg– 1 and glycopyrrolate 0.4 mg·kg– 1 are also administered. Phenylephrine nose drops, 0.25% are applied to each nasal cavity. A #7 silastic nasopharyngeal airway, well lubricated with 2% lidocaine jelly is introduced into the nasopharynx through one nostril (Figure). Mask ventilation is resumed and a propofol infusion is started at a rate appropriate for the vital signs. Using a #16 gauge plastic iv cannula connected by the luer-lock to the distal end of the Sanders “jetting device,” oxygen at 40 psi is jetted into the nasopharyngeal airway for a duration of one or two seconds at a rate of 20 times per minute. Chest excursions and pulse oximetry are used to monitor adequacy of ventilation, while the resident performs nasal fiberoptic endotracheal intubation through the other nostril. This technique of jet ventilation through a nasopharyngeal airway provides optimal conditions for anesthesiology trainees to gain experience in fiberoptic assisted endotracheal intubation. To date we have experienced no complications.

Use of Transnasal Jet Ventilation-Assisted Fiberoptic Intubation in Obstructive Sleep Apnea Patients Undergoing Orthognathic Surgery: A New Technique

r m w s i i m t w h i p w t j bstructive sleep apnea patients undergoing orthogathic surgery present a challenge to the anesthesiolgist. These patients have a complex interplay of soft nd hard tissues contributing to a difficult airway. bstructive sleep apnea patients have been reported o have increased body mass index, hypotonicity of he hypopharynx leading to upper airway collapsibilty, and large tongue and redundant soft palate that an obstruct the airway. Obstructive sleep apnea atients can also have abnormalities in the skeletal raniofacial structures, such as retrusive maxilloandibular complex and retrogenial and steep manibular plane. The combination of these soft and hard issue abnormalities make intubation via direct larynoscope difficult. To manage the difficult airway, fiberoptic intubation as become an essential technique. The guidelines pubished by the American Society of Anesthesiologists, long with other reports, cite the importance of fiberptic intubation for the successful management of any airway challenges. Many propose awake beroptic intubation under mild-to-moderate sedation hat maintains spontaneous ventilation and at the