David C. Chung

Total airway obstruction during local anesthesia in a non-sedated patient with a compromised airway

PurposeTo report a case of complete upper airway obstruction after topicalization with lidocaine in a completely conscious patient with partial upper airway obstruction.Clinical featuresA 69-yr-old man with a history of neck cancer and radiation presented for resection of recurrent neck tumour. No preoperative sedation was given. He had inspiratory and expiratory stridor but had no history of aspiration or swallowing problem. Phonation was distorted but effective. The surgeon was reluctant to perform an awake tracheostomy under local anesthesia. In preparation for a fibrescope-assisted orotracheal intubation, the non-sedated patient was given topical upper airway lidocaine during which he developed total airway obstruction and hypoxemia. He was immediately intubated with a fibrescope. His vocal cords were not edematous although the supraglottic structures appeared to be. The vocal cords were abducted and their movement was limited and not paradoxical. Tumour resection was uneventful upon successful tracheal intubation and general anesthesia. Tracheostomy at the end of the case was difficult, as expected. The patient tolerated the procedures and regained consciousness with no neurologic sequelae.ConclusionDynamic airflow limitation associated with local anesthesia of the upper airway may lead to complete upper airway obstruction in a compromised airway. The main cause may be the loss of upper airway muscle tone, exacerbated by deep inspiration during panic.RésuméObjectifPrésenter un cas d’obstruction complète des voies aériennes supérieures après pulvérisation de lidocaïne chez un patient tout à fait conscient mais souffrant déjà d’obstruction respiratoire partielle.Éléments cliniquesUn homme de 69 ans aux antécédents de cancer du cou et de radiothérapie s’est présenté pour la résection d’une tumeur récurrente au cou. Aucune sédation préopératoire n’a été administrée. Il présentait un stridor inspiratoire et expiratoire, mais n’avait pas d’antécédent de trouble d’aspiration ou de déglutition. La phonation était déformée mais efficace. Le chirurgien était réticent à réaliser une trachéotomie vigile sous anesthésie locale. Pendant la préparation de l’intubation orotrachéale fibroscopique, de la lidocaïne topique a été administrée dans les voies aériennes supérieures du patient éveillé chez qui s’est développée une obstruction totale des voies aériennes et de l’hypoxémie. Il a été immédiatement intubé avec un fibroscope. Ses cordes vocales n’étaient pas œdémateuses même si les structures supraglottiques semblaient l’être. Les cordes vocales étaient écartées et leur mouvement était limité mais non paradoxal. La résection tumorale s’est bien déroulée sous intubation trachéale réussie et anesthésie générale. Comme prévu, la trachéotomie a été difficile à réaliser à la fin de l’opération. Le patient a bien toléré les interventions et s’est réveillé sans séquelles neurologiques.ConclusionUne limitation dynamique du débit d’air associé à l’anesthésie locale des voies aériennes supérieures peut conduire à une obstruction complète des voies respiratoires supérieures en cas d’ob-struction partielle préalable. La principale cause pourrait être la perte du tonus musculaire des voies respiratoires supérieures, exacerbée par l’inspiration profonde pendant les moments de panique.

Use of heliox in critical upper airway obstruction.: Physical and physiologic considerations in choosing the optimal helium:oxygen mix

Heliox has a lower density than oxygen and nitrogen, and can improve ventilation rapidly in patients with critical upper airway obstruction. The choice of the best helium:oxygen ratio depends on whether the predominant problem is hypercarbia or hypoxia. In the former situation, 80% helium should be used, and in the latter, 100% oxygen is appropriate.

Absorption of lidocaine during aspiration anesthesia of the airway.

STUDY OBJECTIVE To determine the optimal solution to use when anesthetizing the airway by aspiration of lidocaine. DESIGN Randomized, double-blind clinical study. SETTING University hospital. PATIENTS 96 adult ASA physical status 1,II, and III patients, scheduled for diagnostic flexible bronchoscopy. INTERVENTIONS Patients were randomized to receive one of 5 solutions of lidocaine: Group A (n = 16): 1% lidocaine, 0.2 mL. kg(-1); Group B (n = 16): 1.5% 0.2 mL. kg(-1); Group C (n = 32): 2% 0.2 mL. kg(-1); Group D (n = 16): 1% 0.3 mL. kg(-1), and Group E (n = 16): 2% 0.3 mL. kg(-1). Fiberoptic bronchoscopy was performed after the airway was anesthetized with this aspiration technique, using the assigned lidocaine solution. The scope was manipulated in the trachea to test for anesthesia. MEASUREMENTS AND MAIN RESULTS Successful airway anesthesia was determined by tolerance to bronchoscopy without sustained coughing, and also by the number of lidocaine supplements, if any, that were given via the bronchoscope. Arterial plasma concentrations of lidocaine were measured in 33 patients from Groups C, D, and E. All solutions provided equally effective anesthesia of the airway. All patients tolerated endoscopy through the vocal cords, and 94 patients required no supplementary anesthesia, or only one dose of lidocaine, during bronchoscopy to the carina. The highest peak plasma concentrations of lidocaine were 5.02 and 6.28 microg. mL. No patient had signs of toxicity. CONCLUSIONS This technique produced anesthesia of the airway to the carina, safely, suitable for awake intubation, in 94 of 95 patients. The use of 1% lidocaine, 0.2 to 0.3 mL. kg(-1), so that the volume is 10 to 20 mL, is recommended.

Anesthesia of the airway by aspiration of lidocaine

PurposeLidocaine instilled onto to the back of the tongue of a supine subject and aspirated has been reported to provide effective topical anesthesia of the airway. The purpose of this study was to observe endoscopically the fate of lidocaine so instilled and document the efficacy of anesthesia for awake fibreoptic intubation.MethodsIn Part I of the study, a fibreoptic bronchoscope was positioned in the pharynx of three volunteers lying supine and the route followed by tinted lidocaine solution instilled onto the back of the protruded tongue during mouth breathing was observed. In Part 2, the airway of 39 patients requiring awake fibreoptic intubation was anesthetized by having them gargle twice with 5 ml lidocaine 2%, followed by instillation of 0.2 ml·kg−1 or 20 ml lidocaine 1.5% (whichever was less) onto the dorsum of their tongues as described above. The efficacy of anesthesia was scored by the patient reaction (coughing or gagging) to instrumentation in the pharynx, at the glottis, and in the trachea; to passage of the tracheal tube into the trachea; and to the presence of the tube in the trachea.ResultsLidocaine instilled on to the back of the tongue was swallowed initially but ultimately pooled in the pharynx and was aspirated. In all patients the trachea was intubated without requiring supplemental lidocaine, and all but one patient tolerated the tracheal tubein situ.ConclusionA combination of lidocaine gargles and lidocaine instilled on to the back of the tongue and aspirated provides effective anesthesia of the pharynx, larynx, and trachea for awake fibreoptic intubation.RésuméObjectifOn a démontré que la lidocaïne instillée sur le dos de la langue d’un sujet en décubitus dorsal et aspirée produit une anesthésie topique efficace des voies aériennes. L’objectif de la présente étude était d’observer sous endoscopie l’action de la lidocaïne instillée et d’en documenter l’efficacité anesthésique pour une fibroscopie vigile.MéthodeDans la Partie I de l’étude, un fibroscope bronchique a été placé dans le pharynx de trois volontaires en décubitus dorsal et la voie empruntée par la lidocaïne colorée instillée sur le dos de la langue en protrusion pendant la respiration buccale a été observée. Dans la Partie 2, dans le but de provoquer l’anesthésie des voies aériennes, 39 patients admis pour une fibroscopie vigile se sont gargarisés deux fois avec 5 ml de lidocaine 2 %, puis ils ont reçu par instillation 0,2 ml·kg−1 ou 20 ml de lidocaïne 1,5 % (peu importe la plus faible) sur le dos de la langue. L’efficacité de l’anesthésie a été cotée selon la réaction du patient (toux ou haut-le-coeur) à l’intubation du pharynx, à la glotte et dans la trachée; au passage du tube endotrachéal dans la trachée et à la présence du tube dans la trachée.RésultatsLa lidocaïne instillée a été avalée initialement, mais plus tard, réunie dans le pharynx et aspirée. Chez tous les patients, l’intubation endotrachéale n’a pas nécessité de lidocaïne supplémentaire, et tous les patients, sauf un, ont toléré le tube endotrachéalin situ.ConclusionUne combinaison de lidocaïne administrée par gargarisme et de lidocaine instillée sur le dos de la langue et aspirée produit une anesthésie efficace du pharynx, du larynx et de la trachée lors de la fibroscopie vigile.

Gabapentin for the treatment and prophylaxis of cluster headache.

Background and Objectives Cluster headache is an uncommon debilitating condition for which effective management remains a challenge. We describe the use of gabapentin in the treatment and prophylaxis of cluster headache in a patient who was refractory to other treatments. Case Report A 38-year-old man had a history of intermittent right-side headaches for 24 years, diagnosed as cluster headache. He received only partial relief from a range of conventional treatments. A trial with gabapentin 300 mg twice daily was tried and found to be effective in treatment and prophylaxis of his headaches. Conclusion Gabapentin was effective in the treatment of a patient with cluster headache. Further investigation of gabapentin compared with conventional treatments and placebo is warranted.

Lung isolation for the prevention of air embolism in penetrating lung trauma. A case report

Purpose: To illustrate a new airway and ventilatory management strategy for patients with unilateral penetrating lung injury. Emphasis is placed on avoiding positive pressure ventilation (PPV)-induced systemic air/gas embolism (SAE) through traumatic bronchiole-pulmonary venous fistulas.Clinical Features: A 14-yr-old male, stabbed in the left chest, presented with hypovolemia, left hemopneumothorax, an equivocal acute abdomen, and no cardiac or neurological injury. In view of the risk of SAE, we did not ventilate the left lung until any fistulas, if present, had been excised. After pre-oxygenation, general anesthesia was induced and a left-sided double-lumen tube (DLT) was placed to allow right-lung ventilation. Bronchoscopy was performed. The surgeons performed a thorascopic wedge resection of the lacerated lingula. Upon completion of the repair, two-lung ventilation was instituted while the ECG, pulse oximetry, PETCO2, and blood pressure were monitored. Peak inflation pressure was increased slowly and was well tolerated up to 50 cm H2O. The patient’s intravascular status was maintained normal.Conclusion: Patients with lung trauma are at risk of developing SAE when their lungs are ventilated with PPV. In a unilateral case, expectant non-ventilation of the injured lung until after repair is recommended.RésuméObjectif: Illustrer une nouvelle façon de protéger les voies aériennes et d’assurer la ventilation chez des patients victimes de lésions pulmonaires unilatérales par pénétration. On veut surtout éviter l’aéroembolie ou l’embolie gazeusesystémique (AES) induite par la ventilation à pression positive (VPP) au travers de fistules brochioliques et veineuses pulmonaires.Éléments cliniques: Un garçon de 14 ans, poignardé au côté gauche, présentait une hypovolémie, un hémopneumothorax gache, un abdomen aigu possible, mais aucune lésion cardiaque ou neurologique. Étant donné le risque d’AES, la ventilation du poumon gauche a été retardée jusqu’à ce que toute fistule possible ait été excisée. Après une pré-oxygénation, l’anesthésie générale a été induite et un tube à double lumière gauche (TDL) a été inséré pour permettre la ventilation du poumon droit. On a procédé à une brochoscopie. Les chirurgiens ont réalisé une résection cunéiforme thoracoscopique de la lingula lacérée. Une fois la réparation terminée, la ventilation bipulmonaire a été instaurée tandis que l’ECG, l’oxymétrie pulsée, la PETCO2 et la tension artérielle étaient placés sous monitorage. La pression de distension maximale a été augmentée lentement et a été bien tolérée jusqu’à 50 cm H2O. L’état intravasculaire a été maintenu normal.Conclusion: Les patients victimes de truamatisme pulmonaire sont à risque de subir une AES lorsque leurs poumons sont ventilés sous une VPP. Dans le cas d’un traumatisme unilatéral, il est recommandé de ne pas utiliser la ventilation du poumon lésé avant la fin de la réparation.

A modified Williams airway intubator to assist fibreoptic intubation

To the Editor: The Williams airway intubator I is found by many authors to be the preferred conduit to facilitate fibreoptic tracheal intubation. 2,a Because it was originally designed to assist blind orotracheal intubation, it offers easy access for the fibreoptic scope to pass through the glottis into the trachea while the endotracheal tube can be threaded through its circular lumen. However, to remove the Intubator after successful intubation is cumbersome: it can be extracted only through the proximal end of the endotracheal tube with the connector detached. To overcome this difficulty, I have modified the intubator by cutting a 7 mm wide slot in its anterior wall (see Figure below). With this slot, the fibreoptic scope can be eased out of the intubator once it is in position before the

Is the Parker Flex-Tip tube really superior to the standard tube for fiberoptic orotracheal intubation?

To the Editor:—Dr. Kristensen has concluded that during intubation with the use of a flexible fiberscope, the use of the Parker Flex-Tube results in a significantly lower rate of repositioning and repeated attempts at passing the tube into the trachea, compared to a standard endotracheal tube. We believe it would be more appropriate to conclude that the Parker tube is better only when the standard tube is improperly oriented during passage. Dr. Kristensen reported that once the standard tube was rotated counterclockwise by 90 degrees, its success rate improved to 26 out of 38 attempts. This was essentially the same as the success rate (27 out of 38 attempts) of the Parker tube and is consistent with our experience with the standard tube. Why not simply start with the standard tube rotated counterclockwise by 90 degrees? The Parker tube requires a higher cuff pressure, which, in our opinion, makes it less desirable. The simple technique of rotating the standard tube counterclockwise by 90 degrees during the first attempt along a fiberoptic bronchoscope has been our standard practice for years, thanks to a suggestion by Katsnelson et al. in 1992. Eighteen years ago, Cossham proposed rotating a standard tube counterclockwise by 90 degrees to facilitate passage along a gum-elastic bougie, and in 1990, Dogra et al. demonstrated convincingly the usefulness of this technique. Granted, this technique may not be widely appreciated, perhaps because the gum-elastic bougie is not used in some parts of the world and the use of fiberoptic bronchoscopy is infrequent. As such, Dr. Kristensens’study should help to popularize this important “trick.”

Diluted venous blood appears arterial: implications for central venous cannulation

Implications There is always a danger of arterial puncture during central venous access. One can usually identify an inadvertent arterial puncture when the aspirated blood is bright red. This sign is removed if one were to put saline in the aspirating syringe, as dusky venous blood turns bright red on dilution.

A pharmacokinetic model for factor VIII dosing during active haemorrhage in patients with haemophilia A

A theoretical one‐compartment pharmacokinetic model is described, the aim of which is to guide factor VIII replacement therapy in patients with haemophilia A suffering from significant and ongoing haemorrhage. Based on our calculations, plasma factor VIII concentrations can decrease at a rapid rate even with non‐severe blood loss.