Emergency ventilation with the Ventrain® through an airway exchange catheter in a porcine model of complete upper airway obstruction.

PURPOSE: During difficult airway management, oxygen insufflation through airway-exchange and intubating catheters (AEC/IC) can lead to life-threatening hyperinflation. Ventrain® was originally designed to facilitate emergency ventilation using active expiration through short, small-bore cannulas. Herein, we studied its efficacy (oxygenation and ventilation) and safety (avoidance of hyperinflation) in a long, small-bore AEC. METHODS: In six anesthetized pigs, the upper airway was obstructed, except for a 100 cm long, 3 mm internal diameter AEC. After apneic desaturation to a peripheral oxygen saturation (SpO2) of < 70%, ventilation through the AEC was started with Ventrain at an oxygen flow of 15 L·min-1, a frequency of 30 breaths·min-1, and an inspiration/expiration ratio of approximately 1:1. It was continued for ten minutes. RESULTS: Within one minute, severe hypoxia was reversed from a median [interquartile range] arterial saturation (SaO2) of 48 [34-56] % before initiation of Ventrain ventilation to 100 [99-100] % afterward (median difference 54%; 95% confidence interval [CI] 44 to 67; P = 0.028). In addition, hypercarbia was reversed from PaCO2 of 59 [53-61] mmHg to 40 [38-42] mmHg (median difference of -18 mmHg; 95% CI -21 to -15; P = 0.028). After ten minutes of Ventrain use, peak inspiratory and end-expiratory pressures were lower than during baseline pressure-controlled ventilation (8 [7-9] mmHg vs 12 [10-14] mmHg and -2 [-3 to +1] mmHg vs 4 [2 to 4] mmHg, respectively; P = 0.027 for both). No hemodynamic deterioration occurred. CONCLUSION: Ventrain provides rapid reoxygenation and effective ventilation through a small-bore AEC in pigs with an obstructed airway. In clinical emergency situations of obstructed airways, this device may be able to overcome problems of unintentional hyperinflation and high intrapulmonary pressures when ventilating through long, small-bore catheters and could therefore minimize the risks of barotrauma and hemodynamic instability.

Students insert the laryngeal tube quicker and more often successful than the esophageal-tracheal combitube in a manikin.

BACKGROUND: Endotracheal intubation remains the standard of airway management. Because intubation skills are difficult to acquire, for medical students teaching of easier to learn techniques should be considered. METHODS: We retrospectively analyzed data that were collected in a University teaching facility. 264 medical students were taught how to use laryngeal tube (LT) and Esophageal Tracheal Combitube((R)) (ETC) in a manikin. The students underwent one of two different types of extraglottic airway management training consisting of either long lecture (30min) and intensive training (2h) (group IT, n=48), or brief (10min) lecture and 20min of training (group BT, n=216). Both groups underwent a test 6 weeks after training, group IT had an additional test 24h after training. RESULTS: After 24h students in group IT were faster using the LT than the ETC (31.7s+/-2.1 vs. 51.9s+/-5.8, p<0.001). Up to 6 weeks after training students were able to place the LT significantly faster than the ETC in both groups (26.5s+/-2.1 vs. 53.9s+/-5.8 group IT and 43.4s+/-1.6 vs. 103.8s+/-4.4 group BT, p<0.001). At 24h and 6 weeks following intensive training, there was no statistical difference in the time required for insertion of either device. CONCLUSION: Following different training scenarios in a manikin, students were able to place the LT much faster than the ETC. Even brief training was sufficient to generate short insertion times for the LT.

The level of cardiac output affects the relationship and agreement between pulmonary artery and transpulmonary aortic thermodilution measurements in an animal model.

OBJECTIVE: The authors investigated the relationship between pulmonary artery and transpulmonary aortic thermodilution cardiac output measurements under conditions of increasing cardiac output (CO). DESIGN: Animal study with repeated simultaneous measurements comparing 2 cardiac output measurement techniques. SETTING: Experimental animal facility of a university hospital. PARTICIPANTS: Ten female pigs. INTERVENTIONS: In anesthetized pigs, an aortic thermistor catheter and a pulmonary artery catheter (PAC) were inserted. Then dobutamine was infused under continuous cardiac output (CCO) monitoring to target different levels of CO. After each L/min increase of CCO simultaneous aortic and PAC thermodilution, CO measurements were performed by using a bolus injection of cooled normal saline and the amount of thermal indicator loss (TL) was calculated. MEASUREMENTS AND MAIN RESULTS: Pooled analysis of CO data with the method of Bland and Altman showed that aortic thermodilution CO was higher than PAC thermodilution CO with a bias of 3.8% +/- 11.1%. The range of TL was 30.4% to -10.1%. Differential analysis according to the range of CO revealed that, in each animal under conditions of low CO, aortic thermodilution CO was higher than PAC thermodilution CO, whereas results were inverse under conditions of high CO. CONCLUSIONS: The authors concluded that the amount of CO differentially affects the relationship between aortic and PAC thermodilution CO. TL and recirculation may be the explanation for this finding.