Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 1. Difficult airway management encountered in an unconscious patient.

PURPOSE: Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the literature on airway management has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This first of two articles addresses difficulty encountered with airway management in an unconscious patient. SOURCE: Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians, were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence was lacking, statements are based on group consensus. FINDINGS AND KEY RECOMMENDATIONS: Most studies comparing video laryngoscopy (VL) with direct laryngoscopy indicate a higher first attempt and overall success rate with VL, and lower complication rates. Thus, resources allowing, the CAFG now recommends use of VL with appropriately selected blade type to facilitate all tracheal intubations. If a first attempt at tracheal intubation or supraglottic airway (SGA) placement is unsuccessful, further attempts can be made as long as patient ventilation and oxygenation is maintained. Nevertheless, total attempts should be limited (to three or fewer) before declaring failure and pausing to consider "exit strategy" options. For failed intubation, exit strategy options in the still-oxygenated patient include awakening (if feasible), temporizing with an SGA, a single further attempt at tracheal intubation using a different technique, or front-of-neck airway access (FONA). Failure of tracheal intubation, face-mask ventilation, and SGA ventilation together with current or imminent hypoxemia defines a "cannot ventilate, cannot oxygenate" emergency. Neuromuscular blockade should be confirmed or established, and a single final attempt at face-mask ventilation, SGA placement, or tracheal intubation with hyper-angulated blade VL can be made, if it had not already been attempted. If ventilation remains impossible, emergency FONA should occur without delay using a scalpel-bougie-tube technique (in the adult patient). The CAFG recommends all institutions designate an individual as "airway lead" to help institute difficult airway protocols, ensure adequate training and equipment, and help with airway-related quality reviews.

RéSUMé: OBJECTIF: Depuis la dernière publication des lignes directrices du Canadian Airway Focus Group (CAFG) en 2013, la littérature sur la prise en charge des voies aériennes s'est considérablement étoffée. Le CAFG s'est donc réuni à nouveau pour examiner la littérature et mettre à jour ses recommandations de pratique. Ce premier article de deux traite de la prise en charge des voies aériennes difficiles chez un patient inconscient. SOURCES: Des sujets de recherche ont été assignés aux membres du Canadian Airway Focus Group, qui compte des médecins anesthésistes, urgentologues et intensivistes. Les recherches ont été menées dans les bases de données Medline, EMBASE, Cochrane Central Register of Controlled Trials et CINAHL. Les résultats ont été présentés au groupe et discutés lors de vidéoconférences toutes les deux semaines entre avril 2018 et juillet 2020. Les recommandations du CAFG sont fondées sur les meilleures données probantes publiées. Si les données probantes de haute qualité manquaient, les énoncés se fondent alors sur le consensus du groupe. CONSTATATIONS ET RECOMMANDATIONS CLéS: La plupart des études comparant la vidéolaryngoscopie à la laryngoscopie directe indiquent un taux de réussite plus élevé à la première tentative et globalement avec la vidéolaryngoscopie, ainsi que des taux de complication inférieurs. Ainsi, les ressources le permettant, le CAFG recommande dorénavant l'utilisation de vidéolaryngoscopes avec le type de lame convenablement sélectionné pour faciliter toutes les intubations trachéales. En cas d'échec de la première tentative d'intubation trachéale ou d'échec de positionnement du dispositif supraglottique (DSG), d'autres tentatives peuvent être entreprises tant que la ventilation et l'oxygénation du patient le permettent. Néanmoins, le nombre total de tentatives devrait être limité, à trois ou moins, avant de déclarer un échec et de considérer les options de « stratégie de retrait ¼. En cas d'échec de l'intubation, les options de stratégie de retrait chez un patient toujours oxygéné comprennent l'éveil (si possible), la temporisation avec un DSG, une dernière tentative d'intubation trachéale à l'aide d'une technique différente, ou une cricothyroïdotomie. L'échec de l'intubation trachéale, de la ventilation au masque facial et de la ventilation via un DSG accompagné d'une hypoxémie présente ou imminente, définit une urgence « impossible de ventiler, impossible d'oxygéner ¼. Le bloc neuromusculaire doit alors être confirmé ou mis en place, et une tentative finale de ventilation au masque, de positionnement du DSG ou d'intubation trachéale avec une lame de vidéolaryngoscopie hyper-angulée peut être réalisée, si cette approche n'a pas encore été essayée. Si la ventilation demeure impossible, une cricothyroïdotomie d'urgence devrait être réalisée sans délai utilisant une technique de scalpel-bougie-tube (chez le patient adulte). Le CAFG recommande à toutes les institutions de désigner une personne comme « leader des voies aériennes ¼ afin d'assister à la mise en place de protocoles pour les voies aériennes difficiles, d'assurer une formation et un équipement adéquats et d'aider aux examens de la qualité en rapport avec les voies aériennes.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 2. Planning and implementing safe management of the patient with an anticipated difficult airway.

PURPOSE: Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated. SOURCE: Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus. FINDINGS AND KEY RECOMMENDATIONS: Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient's tolerance for withdrawal of airway support and whether re-intubation might be difficult.

RéSUMé: OBJECTIF: Depuis la dernière publication des lignes directrices du Canadian Airway Focus Group (CAFG) en 2013, la littérature sur la prise en charge des voies aériennes s'est considérablement étoffée. Le CAFG s'est donc réuni à nouveau pour examiner la littérature et mettre à jour ses recommandations de pratique. Ce deuxième article traite de l'évaluation des voies aériennes, de la prise de décision et de la mise en œuvre sécuritaire d'une stratégie de prise en charge des voies aériennes lorsque des difficultés sont anticipées. SOURCES: Des sujets de recherche ont été assignés aux membres du Canadian Airway Focus Group, qui compte des médecins anesthésistes, urgentologues et intensivistes. Les recherches ont été réalisées dans les bases de données Medline, EMBASE, Cochrane Central Register of Controlled Trials et CINAHL. Les résultats ont été présentés au groupe et discutés lors de vidéoconférences toutes les deux semaines entre avril 2018 et juillet 2020. Les recommandations du CAFG sont fondées sur les meilleures données probantes publiées. Si les données probantes de haute qualité manquaient, les énoncés se fondent alors sur le consensus du groupe. CONSTATATIONS ET RECOMMANDATIONS CLéS: Avant d'amorcer la prise en charge des voies aériennes, une stratégie documentée devrait être formulée pour chaque patient, en fonction de l'évaluation de ses voies aériennes. L'examen au chevet devrait rechercher les prédicteurs de difficultés pour la ventilation au masque, l'intubation trachéale utilisant la vidéolaryngoscopie ou la laryngoscopie directe, l'utilisation d'un dispositif supraglottique, ainsi que pour la cricothyroïdotomie d'urgence. La physiologie du patient et ses problématiques contextuelles devraient également être évaluées. Les difficultés anticipées devraient inciter à prendre des décisions éclairées sur la façon la plus sécuritaire de procéder à la prise en charge des voies aériennes. L'intubation trachéale éveillée peut procurer une marge de sécurité supplémentaire lorsqu'on s'attend à ce que la vidéolaryngoscopie ou la laryngoscopie directe soient impossibles, lorsqu'on prévoit des difficultés pour plus d'un mode de prise en charge des voies aériennes (p. ex., intubation trachéale et ventilation au masque), ou lorsque la difficulté prévue coïncide avec des problèmes physiologiques ou contextuels importants. En cas de choix de prise en charge des voies respiratoires du patient après induction de l'anesthésie générale malgré les difficultés prévues, les directives à l'équipe devraient inclure les déclencheurs pour passer d'une technique à l'autre, l'aide d'experts disponibles et l'équipement requis disponible. Des difficultés imprévues lors de la prise en charge des voies aériennes peuvent toujours survenir, de sorte que la personne responsable de la prise en charge des voies aériennes devrait avoir une stratégie pour chaque patient, et l'établissement doit rendre facilement disponible le matériel pour la prise en charge des voies aériennes difficiles. L'extubation trachéale du patient à risque doit également être soigneusement planifiée, y compris l'évaluation de la tolérance du patient lors du retrait du dispositif de soutien des voies aériennes et d'une ré-intubation potentiellement difficile.

Orogastric tube insertion using the new gastric tube guide: first experiences from a manikin study.

BACKGROUND: Orogastric tube placement is a common procedure routinely used in clinical anesthesiology and intensive care medicine. Nevertheless high failure rates and severe complications have been reported. We conducted this study to evaluate if the usage of the new gastric tube guide would speed up the placement of orogastric tubes and ease the procedure. METHODS: Thirty one professionals were given a hands-on-training in orogastric tube placement in a simulation manikin without and with the gastric tube guide. Afterwards they performed both methods in randomized order. We recorded the placement time, counted the required attempts and asked the participants to rate their experience with both methods. RESULTS: The median placement time using the gastric tube guide was 14 s compared to 25 s without the device. In addition all participants were able to place the orogastric tube when using the gastric tube guide compared to 26/31 (84%) without it. Furthermore 26/31 (84%) users preferred the gastric tube guide over the standard method. CONCLUSION: Our results show that using the gastric tube guide to place orogastric tubes in a manikin led to a significant shorter placement time and a higher overall success rate.

Topical Airway Anesthesia for Awake-endoscopic Intubation Using the Spray-as-you-go Technique with High Oxygen Flow.

A patient's willingness to cooperate is an absolute precondition for successful awake intubation of the trachea. Whilst drug-sedation of patients can jeopardize their spontaneous breathing, topical anesthesia of the airway is a popular technique. The spray-as-you-go technique represents one of the simplest opportunities to anesthetize the airway mucosa. The application of local anesthetic through the working channel of the flexible endoscope is a widespread practice for anesthetists as well as pulmonologists. There is neither need for additional devices nor special training as a pre-requisite to perform this technique. However, a known clinical problem is the coughing and gagging reflex that may occur when the liquid anesthetic strikes the airway mucosa and other sensitive structures like the vocal cords. This can be avoided by the use of oxygen applied through the working channel with the aim of fogging the local anesthetic into finer particles. Furthermore, the oxygen flow provides a higher oxygen supply and contributes to a better view, dispersing mucus secretions and blood away from the lens. Using an atomizer with a high oxygen flow of 10 L/min we maximized these benefits, caused less coughing and had more satisfied and therefore cooperative patients. Possible, but very rare complications of using oxygen flow including gastric insufflation, organ rupture or barotrauma did not arise. We attribute the complication-free use of high oxygen flow to the design of the set, which permits flow and pressure release.

LMA Supreme™ and Ambu® AuraGain™ in anesthetized adult patients: a prospective observational study.

BACKGROUND: Second-generation laryngeal masks with gastric access are increasingly used in daily practice and expand the indications for laryngeal masks in the OR. Only limited data exist comparing different types of laryngeal masks. We investigated the second-generation laryngeal masks LMA Supreme™ and Ambu® AuraGain™ in a clinical setting. We hypothesized that the two devices would be comparable in terms of success rate and airway complications. METHODS: After approval from the local ethics committee, data were collected in a prospective trial. Endpoints were success rate, time to insertion and airway morbidity. Anesthesiologists used either the Supreme (Teleflex Medical GmbH) or Gain (Ambu GmbH) laryngeal mask. Patients <18 years and those with a possible risk of regurgitation were excluded. RESULTS: Data from 351 adult patients were documented (Supreme N.=177; Gain N.=174). Success rate for first attempt was 80% (Supreme) and 72% (Gain; P=0.08). Overall success rate was 89% and 92%, respectively (P=0.38). Providers with minimal experience were more successful at first attempt using Supreme (95%), compared to Gain (67%; P=0.01). The median insertion time was shorter in Supreme at 18 s [interquartile range (IQR), 14-25 s] compared to 30 s for Gain [18-41s] (P<0.0001). A higher incidence of airway complications was observed after device removal for Gain (P=0.009). CONCLUSIONS: Supreme was superior to Gain in terms of insertion time and airway morbidity. Novices were more successful at first attempt using Supreme. These differences between supraglottic airway devices might be due to the different shapes and materials of the masks.

[Awake video laryngoscopy - an alternative to awake fiberoptic intubation?] / Wache Videolaryngoskopie.

INTRODUCTION: Awake video laryngoscopy is a novel option in airway management that is drawing more and more attention as an alternative to awake endoscopic guided intubation.Main issues: Intubation under preserved spontaneous breathing is the safest method to secure the expected difficult airway. In direct comparisons to awake flexible endoscopic intubation, awake video laryngoscopy achieves satisfactory intubation times and a high acceptance of patients and anesthesiologists. Specific cases, in particular very limited mouth opening or sub-glottic masses, require awake flexible endoscopic intubation. Sufficient topical anesthesia and a sophisticated sedation protocol are prerequisites for successful awake video laryngoscopy. CONCLUSION: Awake video laryngoscopy cannot fully replace flexible endoscopic intubation. It is a useful option, but it must be considered that this technique is not suitable for all types of airways, patients or even anesthesiologists. Expertise and adequate practice is mandatory for both techniques. Careful planning, an appropriate blade design and a high expertise in video laryngoscopy are crucial for a successful intubation.

Microbial contamination of anesthetic syringes in relation to different handling habits.

This single-center study prospectively assessed the microbial contamination of anesthetic syringes handled perioperatively under different conditions. We documented high rates of bacterial contamination, with strong but statistically nonsignificant differences between handling groups. Our results identify skin contact as the main source of contamination, and thus we emphasize the impact of proper hand hygiene.

Effects of levosimendan on hemodynamics, local cerebral blood flow, neuronal injury, and neuroinflammation after asphyctic cardiac arrest in rats.

OBJECTIVES: Despite advances in cardiac arrest treatment, high mortality and morbidity rates after successful cardiopulmonary resuscitation are still a major clinical relevant problem. The post cardiac arrest syndrome subsumes myocardial dysfunction, impaired microcirculation, systemic inflammatory response, and neurological impairment. The calcium-sensitizer levosimendan was able to improve myocardial function and initial resuscitation success after experimental cardiac arrest/cardiopulmonary resuscitation. We hypothesized that levosimendan exerts beneficial effects on cerebral blood flow, neuronal injury, neurological outcome, and inflammation 24 hours after experimental cardiac arrest/cardiopulmonary resuscitation. DESIGN: Laboratory animal study. SETTING: University animal research laboratory. SUBJECTS: Sixty-one male Sprague-Dawley rats. INTERVENTIONS: Animals underwent asphyxial cardiac arrest/cardiopulmonary resuscitation, randomized to groups with levosimendan treatment (bolus 12 µg/kg and infusion for 3 hr [0.3 µg/min/kg]) or vehicle (saline 0.9% bolus and infusion for 3 hr [equivalent fluid volume]). Cardiac index, local cerebral blood flow, and hemodynamic variables were measured for 180 minutes after cardiac arrest/cardiopulmonary resuscitation. Behavioral and neurological evaluations were conducted 24 hours after cardiac arrest/cardiopulmonary resuscitation. Furthermore, neuronal injury, expressed as Fluoro-Jade B-positive cells in the hippocampal formation, cortical and hippocampal inflammatory cytokine gene expression, and blood plasma interleukin-6 values were assessed. MEASUREMENTS AND MAIN RESULTS: Treatment with levosimendan reduced neuronal injury and improved neurological outcome after 24 hours of reperfusion and resulted in elevated cardiac index and local cerebral blood flow compared with vehicle after cardiac arrest/cardiopulmonary resuscitation. Mean arterial blood pressure was reduced during the early reperfusion period in the levosimendan group. Cortical and hippocampal inflammatory cytokine gene expression and blood plasma interleukin-6 levels were not influenced. CONCLUSIONS: Levosimendan increased cerebral blood flow after experimental cardiac arrest/cardiopulmonary resuscitation. This effect coincided with reduced neuronal injury and improved neurologic outcome. Findings seem to be independent of inflammatory effects because no effects by levosimendan on cerebral or systemic inflammation could be detected. In summary, levosimendan is a promising agent to improve neurological outcome after cardiac arrest/cardiopulmonary resuscitation.

Effects of a single-dose hypertonic saline hydroxyethyl starch on cerebral blood flow, long-term outcome, neurogenesis, and neuronal survival after cardiac arrest and cardiopulmonary resuscitation in rats*.

OBJECTIVE: The beneficial effects of hypertonic saline on neuronal survival and on cerebral blood flow have been shown in several animal models of global and focal brain ischemia. Because of the potential benefits of hypertonic solutions, it is hypothesized that hydroxyethyl starch enhances cerebral blood flow and improves long-term outcome after cardiac arrest and cardiopulmonary resuscitation in an animal model. DESIGN: Laboratory animal study. SETTING: University animal research laboratory. SUBJECTS: Fifty-nine male Sprague-Dawley rats. INTERVENTIONS: Rats were randomized to receive either 7.2% saline/6% hypertonic saline hydroxyethyl starch (4 mL/kg) or vehicle (NaCl 0.9 %) after 9 mins of asphyxic cardiac arrest and cardiopulmonary resuscitation. Local cerebral blood flow and physiologic parameters were evaluated during arrest and early restoration of spontaneous circulation. Survival and neurologic assessment were evaluated over a 7-day observation period. Animals received 5-bromo-2-deoxyuridine for 6 days. Neuronal injury and neurogeneration (5-bromo-2-deoxyuridine positive neurons) were quantified on day 7 after cardiac arrest and cardiopulmonary resuscitation. MEASUREMENTS AND MAIN RESULTS: Hypertonic saline hydroxyethyl starch treatment resulted in an accentuated local cerebral blood flow during early reperfusion, compared to the vehicle group. Animal survival and neurologic outcome were not altered between groups. Neurohistopathological injury was present in hippocampal CA1 and neocortex with no effects of hypertonic saline hydroxyethyl starch on neuronal survival. Increased neurogeneration was found in the dentate gyrus after cardiac arrest/cardiopulmonary resuscitation, which was not influenced by hypertonic saline hydroxyethyl starch administration. CONCLUSIONS: Despite promising results in other models of brain injury, hypertonic saline hydroxyethyl starch failed to improve the outcome when administered after asphyxic cardiac arrest/cardiopulmonary resuscitation in rats. One major difference between the cardiac arrest/cardiopulmonary resuscitation model and other models of brain ischemia is that the effects of asphyxic cardiac arrest involve the whole organism (post-cardiac arrest syndrome) and not exclusively the brain leading to a more severe injury. This might explain why hypertonic saline hydroxyethyl starch has failed to improve outcome in the present model.

Airway management in the intensive care unit.

Airway management in the intensive care unit (ICU) is a challenging procedure and is frequently associated with life threatening complications. The incidence of difficult intubations ranges from 10% to 22%, depending on the setting and the patients in need of endotracheal intubation. Multiple attempts are often needed to secure the airway. Despite the high risk for patients in the ICU setting, the equipment for airway management such as capnometry or alternative devices is not always available. The novel technique of video laryngoscopy has been recently introduced into clinical practice in the operating room. First results from larger studies are very promising, suggesting these new devices to be helpful for successful intubation with fewer attempts in difficult intubation scenarios. At the same time, several reports show that successful use of video laryngoscopes in emergency situations need substantial practical training and expertise in airway management. The use of a protocol for airway management has been shown to decrease complications. Parts of this protocol are appropriate staffing, pre-oxygenation and strategies to avoid cardiovascular complications. In conclusion, high practical skill of airway management is needed in critically ill patients. Monitoring such as capnography and alternative equipment for securing the airway is not just mandatory in the operating room but also in the ICU.

Dose-dependent influence of sevoflurane anesthesia on neuronal survival and cognitive outcome after transient forebrain ischemia in Sprague-Dawley rats.

BACKGROUND: Volatile anesthetics reduce postischemic neurohistopathological injury and improve neurological outcome in various animal models. However, the isoflurane concentrations above 1 minimum alveolar concentration (MAC) have been associated with reduced neuronal survival and impaired functional outcome. The aim of this study was to evaluate if 1.8 MAC sevoflurane alters postischemic neuronal survival and neurologic outcome compared with 0.45 MAC sevoflurane. METHODS: In this study, 20 fasted male Sprague-Dawley rats were randomly assigned to treatment groups with 1 or 4 vol.% sevoflurane end-tidal concentration. Cerebral ischemia was induced by bilateral carotid artery occlusion and hemorrhagic hypotension (BCAO). The cognitive outcome was assessed after 7 days using the object recognition test. Animals were then re-anesthetized and brains were removed for neurohistopathological analysis of the hippocampus (CA1) and cortex using hematoxylin-eosin staining. RESULTS: Physiologic parameters were not different between both the treatment groups. The number of viable neurons (median [Q1, Q3]) in the CA1 region on postischemic day 7 was increased after high-dose sevoflurane compared with low-dose sevoflurane (1645 [453, 1825] vs. 3222 [2920, 3993] neurons/ROI, P < 0.05). Results of the object recognition test were not different between both the treatment groups. CONCLUSIONS: Postischemic neuronal survival was increased with 1.8 MAC compared with 0.45 MAC sevoflurane. Therefore, experimental models of cerebral ischemia should account for neuroprotective effects of sevoflurane with increasing concentrations. To ensure minimal interference of sevoflurane on neuronal survival, a low inspired concentration should be used and fluctuations in the depth of anesthesia should be limited.

Comparison of the McGrath® Series 5 and GlideScope® Ranger with the Macintosh laryngoscope by paramedics.

BACKGROUND: Out-of-hospital endotracheal intubation performed by paramedics using the Macintosh blade for direct laryngoscopy is associated with a high incidence of complications. The novel technique of video laryngoscopy has been shown to improve glottic view and intubation success in the operating room. The aim of this study was to compare glottic view, time of intubation and success rate of the McGrath® Series 5 and GlideScope® Ranger video laryngoscopes with the Macintosh laryngoscope by paramedics. METHODS: Thirty paramedics performed six intubations in a randomised order with all three laryngoscopes in an airway simulator with a normal airway. Subsequently, every participant performed one intubation attempt with each device in the same manikin with simulated cervical spine rigidity using a cervical collar. Glottic view, time until visualisation of the glottis and time until first ventilation were evaluated. RESULTS: Time until first ventilation was equivalent after three intubations in the first scenario. In the scenario with decreased cervical motion, the time until first ventilation was longer using the McGrath® compared to the GlideScope® and AMacintosh (p < 0.01). The success rate for endotracheal intubation was similar for all three devices. Glottic view was only improved using the McGrath® device (p < 0.001) compared to using the Macintosh blade. CONCLUSIONS: The learning curve for video laryngoscopy in paramedics was steep in this study. However, these data do not support prehospital use of the McGrath® and GlideScope® devices by paramedics.

Transpulmonary cardiac output measurement in a rat model of cardiac arrest and CPR: impact of vascular access.

OBJECTIVE: The present study investigated the impact of the vascular access site for cardiac output (CO) measurement by thermodilution on survival and neurohistopathological injury in a rat model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Secondary the influence of the vascular access site on cardiac output measurements was examined. METHODS: Rats underwent asphyxial CA and CPR. Thermocouple probes were either placed via the femoral artery into the bifurcation of abdominal aorta/iliac artery (Femoral) or via the carotid artery into the aortic arch (Carotid). CPR was initiated after 9 min CA. Local cerebral blood flow (lCBF) and CO were assessed for 120 min after restoration of spontaneous circulation. Neurohistopathological injury was determined using Fluoro-Jade B staining. RESULTS: Survival was reduced in the Carotid group compared to the Femoral group (p<0.01). Fluoro-Jade B staining in the hippocampus showed no difference between CA groups. CO measurements were comparable between femoral and carotid artery access sites. lCBF revealed a delayed hyperperfusion in the Carotid group only. CONCLUSIONS: The present study demonstrates the influence of the vascular access site for placing thermocouple probes for CO measurement on animal survival after CA/CPR. CO did not differ between the two access sites with consequential different detection sites. Use of the femoral access for CO measurement is recommended for long-term survival after CA/CPR.

Rigid fibrescope Bonfils: use in simulated difficult airway by novices.

BACKGROUND: The Bonfils intubation fibrescope is a promising alternative device for securing the airway. We examined the success rate of intubation and the ease of use in standardized simulated difficult airway scenarios by physicians. We compared the Bonfils to a classical laryngoscope with Macintosh blade. METHODS: 30 physicians untrained in the use of rigid fibrescopes but experienced in airway management performed endotracheal intubation in an airway manikin (SimMan, Laerdal, Kent, UK) with three different airway conditions. We evaluated the success rate using the Bonfils (Karl Storz, Tuttlingen, Germany) or the Macintosh laryngoscope, the time needed for securing the airway, and subjective rating of both techniques. RESULTS: In normal airway all intubations were successful using laryngoscope (100%) vs. 82% using the Bonfils (p < 0.05). In the scenario "tongue oedema" success rate using the Macintosh laryngoscope was 67% and 83% using the Bonfils. In the scenario "decreased cervical range of motion with jaw trismus", success rate using the Macintosh laryngoscope was 84% vs. 76%. In difficult airway scenarios time until airway was secured did not differ between the two devices. Use of Bonfils was rated "easier" in both difficult airway scenarios. CONCLUSION: The Bonfils can be successfully used by physicians unfamiliar with this technique in an airway manikin. The airway could be secured with at least the same success rate as using a Macintosh laryngoscope in difficult airway scenarios. Use of the Bonfils did not delay intubation in the presence of a difficult airway. These results indicate that intensive special training is advised to use the Bonfils effectively in airway management.