X. Combes

Intravenous enoxaparin or unfractionated heparin in primary percutaneous coronary intervention for ST-elevation myocardial infarction: the international randomised open-label ATOLL trial

BACKGROUND Primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction has traditionally been supported by unfractionated heparin, which has never been directly compared with a new anticoagulant using consistent anticoagulation and similar antiplatelet strategies in both groups. We compared traditional heparin treatment with intravenous enoxaparin in primary PCI. METHODS In a randomised open-label trial, patients presenting with ST-elevation myocardial infarction were randomly assigned (1:1) to receive an intravenous bolus of 0·5 mg/kg of enoxaparin or unfractionated heparin before primary PCI. Wherever possible, medical teams travelling in mobile intensive care units (ambulances) selected, randomly assigned (using an interactive voice response system at the central randomisation centre), and treated patients. Patients who had received any anticoagulant before randomisation were excluded. Patients and caregivers were not masked to treatment allocation. The primary endpoint was 30-day incidence of death, complication of myocardial infarction, procedure failure, or major bleeding. The main secondary endpoint was the composite of death, recurrent acute coronary syndrome, or urgent revascularisation. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCT00718471. FINDINGS 910 patients were assigned to treatment with enoxaparin (n=450) or unfractionated heparin (n=460). The primary endpoint occurred in 126 (28%) patients after anticoagulation with enoxaparin versus 155 (34%) patients on unfractionated heparin (relative risk [RR] 0·83, 95% CI 0·68-1·01, p=0·06). The incidence of death (enoxaparin, 17 [4%] vs heparin, 29 [6%] patients; p=0·08), complication of myocardial infarction (20 [4%] vs 29 [6%]; p=0·21), procedure failure (100 [26%] vs 109 [28%]; p=0·61), and major bleeding (20 [5%] vs 22 [5%]; p=0·79) did not differ between groups. Enoxaparin resulted in a significantly reduced rate of the main secondary endpoint (30 [7%] vs 52 [11%] patients; RR 0·59, 95% CI 0·38-0·91, p=0·015). Death, complication of myocardial infarction, or major bleeding (46 [10%] vs 69 [15%] patients; p=0·03), death or complication of myocardial infarction (35 [8%] vs 57 [12%]; p=0·02), and death, recurrent myocardial infarction, or urgent revascularisation (23 [5%] vs 39 [8%]; p=0·04) were all reduced with enoxaparin. INTERPRETATION Intravenous enoxaparin compared with unfractionated heparin significantly reduced clinical ischaemic outcomes without differences in bleeding and procedural success. Therefore, enoxaparin provided an improvement in net clinical benefit in patients undergoing primary PCI. FUNDING Direction de la Recherche Clinique, Assistance Publique-Hôpitaux de Paris; Sanofi-Aventis.

Unanticipated difficult airway in anesthetized patients: prospective validation of a management algorithm.

Background: Management strategies conceived to improve patient safety in anesthesia have rarely been assessed prospectively. The authors undertook a prospective evaluation of a predefined algorithm for unanticipated difficult airway management. Methods: After a 2-month period of training in airway management, 41 anesthesiologists were asked to follow a predefined algorithm for management in the case of an unanticipated difficult airway. Two different scenarios were distinguished: “cannot intubate” and “cannot ventilate.” The gum elastic bougie and the Intubating Laryngeal Mask Airway™ (ILMA™) were proposed as the first and second steps in the case of impossible laryngoscope-assisted tracheal intubation, respectively. In the case of impossible ventilation or difficult ventilation, the IMLA was recommended, followed by percutaneous transtracheal jet ventilation. The patient’s details, adherence rate to the algorithm, efficacy, and complications of airway management processes were recorded. Results: Impossible ventilation never occurred during the 18-month study. One hundred cases of unexpected difficult airway were recorded (0.9%) among 11,257 intubations. Deviation from the algorithm was recorded in three cases, and two patients were wakened before any alternative intubation technique attempt. All remaining patients were successfully ventilated with either the facemask (89 of 95) or the ILMA™ (6 of 95). Six difficult-ventilation patients required the ILMA™ before completion of the first intubation step. Eighty patients were intubated with the gum elastic bougie, and 13 required a blind intubation through the ILMA™. Two patients ventilated with the ILMA™ were never intubated. Conclusion: When applied in accordance with a predefined algorithm, the gum elastic bougie and the ILMA™ are effective to solve most problems occurring during unexpected difficult airway management.

Intracuff pressure and tracheal morbidity: Influence of filling Cuff with saline during nitrous oxide anesthesia

Background Diffusion of nitrous oxide into the cuff of the endotracheal tube results in an increase in cuff pressure. Excessive endotracheal tube cuff pressure may impair tracheal mucosal perfusion and cause tracheal damage and sore throat. Filling the cuff of the endotracheal tube with saline instead of air prevents the increase in cuff pressure due to nitrous oxide diffusion. This method was used to test whether tracheal morbidity is related to excess in tracheal cuff pressure during balanced anesthesia. Methods Fifty patients with American Society of Anesthesiologists physical status I or II were randomly allocated to two groups with endotracheal tube cuffs initially inflated to 20–30 cm H2O with either air (group A) or saline (group S). Anesthesia was maintained with isoflurane and nitrous oxide. At the time of extubation, a fiberoptic examination of the trachea was performed by an independent observer, and abnormalities of tracheal mucosa at the level of the cuff contact area were scored. Patients assessed their symptoms (sore throat, dysphagia, and hoarseness) at the time of discharge from the postanesthesia care unit and 24 h after extubation on a 101-point numerical rating scale. Results Cuff pressure increased gradually during anesthesia in group A but remained stable in group S. The incidence of sore throat was greater in group A than in group S in the postanesthesia care unit (76 vs. 20%) and 24 h after extubation (42 vs. 12%;P < 0.05). Tracheal lesions at time of extubation were seen in all patients of group A and in eight patients (32%) of group S (P < 0.05). Conclusion Excess in endotracheal tube cuff pressure during balanced anesthesia due to nitrous oxide diffusion into this closed gas space causes sore throat that is related to tracheal mucosal erosion.

An Algorithm for Difficult Airway Management, Modified for Modern Optical Devices (Airtraq Laryngoscope; LMA CTrach ™)A 2-Year Prospective Validation in Patients for Elective Abdominal, Gynecologic, and Thyroid Surgery

Background: Because algorithms for difficult airway management, including the use of new optical tracheal intubation devices, require prospective evaluation in routine practice, we prospectively assessed an algorithm for difficult airway management that included two new airway devices. Methods: After 6 months of instruction, training, and clinical testing, 15 senior anesthesiologists were asked to use an established algorithm for difficult airway management in anesthetized and paralyzed patients. Abdominal, gynecologic, and thyroid surgery patients were enrolled. Emergency, obstetric, and patients considered at risk of aspiration were excluded. If tracheal intubation using a Macintosh laryngoscope was impossible, the Airtraq laryngoscope (VYGON, Ecouen, France) was recommended as a first step and the LMA CTrach™ (SEBAC, Pantin, France) as a second. A gum elastic bougie was advocated to facilitate tracheal access with the Macintosh and Airtraq laryngoscopes. If ventilation with a facemask was impossible, the LMA CTrach™ was to be used, followed, if necessary, by transtracheal oxygenation. Patient characteristics, adherence to the algorithm, efficacy, and early complications were recorded. Results: Overall, 12,225 patients were included during 2 yr. Intubation was achieved using the Macintosh laryngoscope in 98% cases. In the remainder of the cases (236), a gum elastic bougie was used with the Macintosh laryngoscope in 207 (84%). The Airtraq laryngoscope success rate was 97% (27 of 28). The LMA CTrach™ allowed rescue ventilation (n = 2) and visually directed tracheal intubation (n = 3). In one patient, ventilation by facemask was impossible, and the LMA CTrach™ was used successfully. Conclusions: Tracheal intubation can be achieved successfully in a large cohort of patients with a new management algorithm incorporating the use of gum elastic bougie, Airtraq, and LMA CTrach™ devices.

Comparison of the Accuracy of Noninvasive Hemoglobin Monitoring by Spectrophotometry (SpHb) and HemoCue® with Automated Laboratory Hemoglobin Measurement

Background: The reference method for hemoglobin concentration measurement remains automated analysis in the laboratory. Although point-of-care devices such as the HemoCue® 201+ (HemoCue, Ängelholm, Sweden) provide immediate hemoglobin values, a noninvasive, spectrophotometry-based technology (Radical-7®; Masimo Corp., Irvine, CA) that provides continuous online hemoglobin (SpHb) measurements has been introduced. This clinical study aimed to test the hypothesis that SpHb monitoring was equivalent to that of HemoCue® (the automated hemoglobin measurement in the laboratory taken as a reference method) during acute surgical hemorrhage. Methods: Blood for laboratory analysis was sampled after induction of anesthesia, during surgery according to the requirements of the anesthesiologist, and finally after the transfer of the patient to the recovery room. When each blood sample was taken, capillary samples were obtained for analysis with HemoCue®. SpHb monitoring was performed continuously during surgery. Using the automated hemoglobin measurement in the laboratory as a reference method, the authors tested the hypothesis that SpHb monitoring is equivalent to that of HemoCue®. The agreement between two methods was evaluated by linear regression and Bland and Altman analysis. Results: Eighty-five simultaneous measurements from SpHb, HemoCue®, and the laboratory were obtained from 44 patients. Bland and Altman comparison of SpHb and HemoCue® with the laboratory measurement showed, respectively, bias of −0.02 ± 1.39 g · dl−1 and −0.17 ± 1.05 g · dl−1, and a precision of 1.11 ± 0.83 g · dl−1 and 0.67 ± 0.83 g · dl−1. Considering an acceptable difference of ± 1.0 g · dl−1 with the laboratory measurement, the percentage of outliers was significantly higher for SpHb than for HemoCue® (46% vs. 16%, P < 0.05). Conclusions: Taking automated laboratory hemoglobin measurement as a reference, the study shows that SpHb monitoring with Radical-7® gives lower readings than does the HemoCue® for assessment of hemoglobin concentration during hemorrhagic surgery.

Unanticipated difficult airway management in the prehospital emergency setting: prospective validation of an algorithm.

Background: Difficult intubation management algorithms have proven efficacy in operating rooms but have rarely been assessed in a prehospital emergency setting. We undertook a prospective evaluation of a simple prehospital difficult intubation algorithm. Methods: All of our prehospital emergency physicians and nurse anesthetists were asked to adhere to a simple algorithm in all cases of impossible laryngoscope-assisted tracheal intubation. They received a short refresher course and training in the use of the gum elastic bougie (GEB) and the intubating laryngeal mask airway (ILMA), which were techniques to be used as a first and a second step, respectively. In cases of difficult ventilation with arterial desaturation, IMLA was to be used first. Cricothyroidotomy was the ultimate rescue technique when ventilation through ILMA failed. Patient characteristics, adherence to the algorithm, management efficacy, and early complications were recorded (August 2005–December 2009). Results: An alternative technique to secure the airway was needed in 160 of 2,674 (6%) patients undergoing intubation. Three instances of nonadherence to the algorithm were recorded. GEB was used first in 152 patients and was successful in 115. ILMA was used first in 8 patients and second in the 37 GEB-assisted intubation failures. Forty-five patients were successfully mask-ventilated, and 42 were blindly intubated before reaching the hospital. Cricothyroidotomy was used successfully in a patient with severe upper airway obstruction as a result of pharyngeal neoplasia. Early intubation-related complications occurred in 52% difficult cases. Conclusion: Adherence to a simple algorithm using GEB, ILMA, and cricothyroidotomy solved all difficult intubation cases occurring in a prehospital emergency setting.

Intubating laryngeal mask airway in morbidly obese and lean patients : A comparative study

BACKGROUND The intubating laryngeal mask airway (ILMA) was designed using the characteristics of healthy-weight subjects but was shown to be an effective airway device in morbidly obese patients. The authors compared airway management quality in morbidly obese and lean patients with use of the ILMA. METHODS Fifty morbidly obese and 50 lean patients (mean body mass indexes, 42 and 27 kg/m, respectively) were enrolled in this prospective study. After induction of general anesthesia, characteristics of airway management were judged on safety and efficiency parameters, including success rate at ventilation and intubation and airway management quality criteria, such as the number of patients who required adjustment maneuvers, the number of failed tracheal intubation attempts, the total duration of airway management, and an overall difficulty visual analog scale score. RESULTS The ILMA was successfully inserted and adequate ventilation through the ILMA was achieved in all 100 patients. The success rates of tracheal intubation through the ILMA were similar in obese and lean patients (96% and 94%, respectively). The numbers of failed blind tracheal access attempts and patients who required airway-adjustment maneuvers were significantly reduced in obese patients as compared with lean patients. Four obese patients experienced transient episodes of oxygen desaturation (oxygen saturation < 90%) before adequate bag ventilation was established with the ILMA. CONCLUSION The authors confirmed that the ILMA was an efficient airway device for airway management of both lean and obese patients. In the conditions of this study, the authors observed that airway management with the ILMA was simpler in obese patients as compared with lean patients.

Efficacy and safety of the EZ-IO™ intraosseous device: Out-of-hospital implementation of a management algorithm for difficult vascular access

OBJECTIVE Intraosseous access is a rapid and safe alternative when peripheral vascular access is difficult. Our aim was to assess the safety and efficacy of a semi-automatic intraosseous infusion device (EZ-IO) when using a management algorithm for difficult vascular access in an out-of-hospital setting. METHODS This was a one-year prospective, observational study by mobile intensive care units. After staff training in the use of the EZ-IO device and provision of a management algorithm for difficult vascular access, all vehicles were equipped with the device. We determined device success rate and ease of use, resuscitation fluid volume and drugs administered by the intraosseous route, and complications at insertion site. RESULTS A total of 4666 patients required vascular access. The EZ-IO device was used in 30 cardiac arrest patients (25 adults; 5 children) and 9 adults with spontaneous cardiac activity. The success rate for first insertion was 84%. Overall success rate (max. 2 attempts) was 97%. The device was used for fluid resuscitation in 16 patients (mean volume: 680ml), adrenaline administration in 24 patients, and rapid sequence induction in 2 patients. There was only one local complication (transient local inflammation). CONCLUSIONS On implementation of an algorithm for the management of difficult vascular access, the EZ-IO device proved safe and highly effective in both adult and paediatric patients in an out-of-hospital emergency setting. It is a suitable device for consideration as a first-line option for difficult vascular access in this setting.

Postoperative Obstructive Apnea

UNLABELLED We studied electromyography (EMG) of the geniohyoid muscle (Gh) and diaphragm (Di) in 12 postoperative, premedicated (flunitrazepam 2 mg PO), asymptomatic patients who snored after recovering from general anesthesia, the induction of which was partly achieved by i.v. midazolam. After extubation of the trachea, integrated EMG activity of Gh (E-Gh(MTA)) and Di (E-Di(MTA)) were measured. For Gh, tonic and phasic activity were distinguished. Patients were studied during obstructive apnea, at the end of apnea, while breathing through an artificial Guedel airway, and during quiet breathing 5 min after flumazemil. All patients experienced episodes of postoperative upper airway obstruction and nine became apneic. Flumazenil restored consciousness and predominant tonic E-GhMTA associated with upper airway patency in all patients. Reduced tonic E-GhMTA characterized postoperative obstructive apnea. Resolution of apnea required a burst of both tonic and phasic E-GhMTA associated with intense E-Di(MTA). Breathing through the Guedal airway resulted in patent airway in 8 of 10 patients and was associated with low tonic and phasic E-GhMTA and reduced E-Di(MTA). In this study, we demonstrated that the tonic pharyngeal muscular support modulates airway patency in the postoperative period. Because it is reversed by flumazemil, benzodiazepines are certainly the main cause of airway obstruction in these patients. IMPLICATIONS Upper airway obstruction during recovery from general anesthesia induced by i.v. midazolam is associated with low tonic pharyngeal muscular support, which modulates upper airway patency in the postoperative period.

Video-Assisted Versus Conventional Tracheal Intubation in Morbidly Obese Patients

BackgroundWe compared tracheal intubation characteristics and arterial oxygenation quality during airway management of morbidly obese patients whose trachea was intubated under video assistance with the LMA CTrach™ (SEBAC, Pantin, France) or the Airtraq™ laryngoscope (VYGON, Écouen, France) with that of the conventional Macintosh laryngoscope.MethodsAfter standardized induction of anesthesia, 318 morbidly obese patients scheduled for elective morbid obesity surgery received tracheal intubation with the LMA CTrach™, the Airtraq™ laryngoscope, or the conventional Macintosh laryngoscope. Duration of apnea, time to tracheal intubation, and oxygenation quality during airway management were compared between the LMA CTrach™ and the laryngoscope groups.ResultsPatients’ characteristics were similar in the three groups. The success rate for tracheal intubation was 100% with the LMA CTrach™ and the Airtraq™ laryngoscope. One patient of the Macintosh laryngoscope group received LMA CTrach™ intubation because of early arterial oxygen desaturation associated with unstable facemask ventilation. The duration of apnea was shorter with the LMA CTrach™ than that of the Airtraq™ laryngoscope and the Macintosh laryngoscope. The duration tracheal intubation was shorter with the Airtraq™ laryngoscope than with the Macintosh laryngoscopes and the LMA CTrach™. During airway management, arterial oxygenation was of better quality with the LMA CTrach™ and the Airtraq™ laryngoscope than that of the Macintosh laryngoscope.ConclusionBecause LMA CTrach™ promoted short apnea time and the Airtraq™ laryngoscope allowed early definitive airway, both video-assisted tracheal intubation devices prevented most serious arterial oxygenation desaturation evidenced during tracheal intubation of morbidly obese patients with the conventional Macintosh laryngoscope.