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Department of Anesthesiology, Hartford Hospital, University of Connecticut School of Medicine
Address correspondence and reprint requests to Thomas C. Mort, MD, Senior Associate, Anesthesiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102. Address e-mail to tmort{at}harthosp.org
| Abstract |
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2 versus >2 attempts): hypoxemia (11.8% versus 70%), regurgitation of gastric contents (1.9% versus 22%), aspiration of gastric contents (0.8% versus 13%) bradycardia (1.6% versus 21%), and cardiac arrest (0.7% versus 11%; P < 0.001). Although predictable, this analysis provides data that confirm the number of laryngoscopic attempts is associated with the incidence of airway and hemodynamic adverse events. These data support the recommendation of the ASA Task Force on the Management of the Difficult Airway to limit laryngoscopic attempts to three in lieu of the considerable patient injury that may occur. IMPLICATIONS: Intraoperative blood glucose control with 1 U of insulin for every 150 mg of blood glucose value more than 100 mg/dL added to 100 mL of 5% dextrose in a measured volume set was tested hourly. It is a simple and effective method and combines the advantages of combined glucose insulin and variable rate insulin infusion.
| Introduction |
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| Methods |
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Hartford Hospital has 24-h in-house airway management coverage that is staffed by at least a CA-1 level resident (minimum of 6 mo of training) and an attending anesthesiologist covering all hospital areas except the ED. This area was served by the anesthesia airway team on an emergent or urgent consultative basis. The evolution of the anesthesia team varied over time: attending staff presence throughout the patient evaluation and the intubation procedure was approximately 70% from 19901993 and was ubiquitous after this period (100% between 19932000). The respiratory therapy team with nursing staff assistance supported the patient with bag-valve-mask oxygen supplementation before the arrival of the anesthesia personnel. Clinical judgment to determine the approach to airway management (topical anesthesia, sedatives, opiates, and neuromuscular blocking drugs [NMBD]) were individualized based on the patients airway status, comorbidities, and the primary diagnosis prompting the need for intubation. Ventilation with 100% oxygen before and between prolonged intubation attempts (>30 s) was standard practice. Endotracheal tube verifying devices (disposable CO2, esophageal detector device, or battery-operated capnogram) were available during and after 1995.
After intubation, the personnel performing the tracheal intubation completed a questionnaire that outlined the patients demographics, procedural details, hemodynamic alterations, airway related mishaps, and other miscellaneous complications. Demographics included the patients age, sex, medical history, and primary diagnosis requiring tracheal intubation. Procedural data included patient location, route of intubation, level of training, number of attempts, medications administered for patient preparation, pre- and postintubation hemodynamic data, and complications. The author reviewed each case within 48 h after submission of the questionnaire and discarded incomplete questionnaires (n = 476). Cross-referencing with the departments billing records was performed to determine the number of missed cases.
Complication variables were defined in 1990, as outlined in Table 1, on the basis of the department of anesthesiologys quality improvement data collection so to allow categorization of complications and remained unchanged during the study period. To clarify specific conditions present in critically ill patients (hypotension and hypoxemia): if hypotension was present preintubation (systolic blood pressure <90 mm Hg with mean arterial blood pressure <60 mm Hg), then any further reduction postintubation was categorized as hypotension. Likewise, if vasoactive medications were supporting hemodynamics before the airway intervention, then any increase in their requirements after intubation was categorized as hypotension. If the baseline SpO2 after administration of oxygen or reoxygenation was >90%, then any reduction less than 90% was categorized as hypoxemia. Likewise, if the SpO2 could not be increased to >90% with breathing 100% oxygen, then a 5% point reduction in SpO2 from the baseline administration of oxygen maximum was categorized as hypoxemia. A laryngoscopic attempt was considered as the placing of the blade within the oropharynx with an attempt to pass the endotracheal tube.
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All statistical analyses were performed with SPSS version 11.5 (SPSS Inc, Chicago, IL). Categorical data were analyzed using
2 tests and, where appropriate, Fishers exact probability tests. Logistic regression models were constructed and odds ratios with 95% confidence intervals (95% CI) were calculated to evaluate airway-related and hemodynamic complications. Statistically significant differences and outcomes were determined as a P value <0.05.
| Results |
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Based on the complication variables, the incidence of hypoxemia, overall, was 17.7%, and one third of these cases represented severe hypoxemia (SpO2 <70%). The incidence categorized by intubation attempts varied significantly; endotracheal intubation requiring 2 or fewer attempts was 10.5% versus 70% for more than 2 attempts (Fig. 1 and Table 5). More specifically, the rate for 1 attempt was 4.8%, 2 attempts was 33.1%, 3 attempts was 62%, and 4 or more attempts was 85% (P < 0.001). In their respective intubation categories, severe hypoxemia was distributed disproportionately in those requiring more than 2 attempts (28% of total patients and 40% of the total hypoxemic patients) versus 2 or fewer attempts (1.9% of total patients and 18% of the total hypoxemic patients). Those suffering a single episode of esophageal intubation (EI) had a 51% chance of hypoxemia. Independently, EI increased the risk of hypoxemia nearly 11-fold (95% CI, 7.713.2). Furthermore, patients who experienced 2 or more esophageal intubations had a significant rate of hypoxemia (85% overall; 2 EI, 76%; 3 EI, 96%; and 4 EI, 100%).
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The risk of regurgitation, with or without aspiration, was considerably higher than what anesthesia practitioners are typically accustomed to in the elective situation in the OR. The incidence was very small (1.9%) for those who had their airway secured on 2 or fewer attempts (1 attempt, 1.1%; 2 attempts, 5.2%) and increased 10-fold when 3 or more attempts were required (Table 5 and Fig. 1). Aspiration of gastric contents was minimal for 1 attempt (0.3%) and 2.3% for those requiring 2 attempts. EI independently increased the relative risk of regurgitation (9.6-fold; 95% CI, 6.514.2) and aspiration (8-fold; 95% CI, 4.715.1) considerably.
There was a significant relationship between the various airway-related complications as the number of laryngoscopic attempts accumulated. Often, one complication creates others, most often in patients requiring 3 or more intubation attempts. For example, those who experienced EI had a significant risk of developing hypoxemia (60%). Likewise, 9 of 10 patients who regurgitated developed hypoxemia (91%). Aspirating gastric contents overwhelmingly lead to hypoxemia (95%), of which 30% experienced profound desaturation less than SpO2 <70%.
The location of the intubation took place in several areas of the hospital, as outlined in Table 2. Logistic-regression analysis confirms that the location within the hospital had no statistical bearing on the number of intubation attempts (1 to 2 attempts versus more than 2 attempts and 3 attempts versus 4 or more attempts, individually). However, several airway and hemodynamic complications were significantly influenced by the location of the airway procedure. Patients intubated on the floor had a 3-fold increased risk (95% CI, 1.65.7; P < 0.002) of suffering aspiration compared with other areas. The medical ICU location had an increased risk of regurgitation (2x), hypoxemia was nearly twice as likely in the ED, and there was a 40% reduction in risk of hypoxemia in the neuro-trauma ICU locale when compared with other locations (Table 2). In evaluation of the primary reason for intubation, upper gastrointestinal bleed patients (14.1%), trauma (13.9%), and neurologic-based intubations (13.1%) had a statistically increased need for 3 or more intubation attempts compared with the sepsis and cardiac groups (P < 0.03) but not when compared with the overall group (10%).
The incidence of tachycardia, hypotension, and hypertension showed no statistically significant differences with an increasing number of laryngoscopic attempts. However, the incidence of a bradycardic response, most often associated with a marked reduction in the SpO2, was relatively uncommon (1.6%) in those who were successfully intubated with 1 (1.3%) or 2 attempts (2.6%) but burgeoned to 18.5% when 3 or more attempts were required. As an independent variable, those suffering EI had a substantially increased risk of bradycardia (12-fold; 95% CI, 8.213.3). Nearly 90% of the bradycardia cases had associated severe hypoxemia (SpO2 <70%), and one half of the bradycardic episodes culminated in cardiac arrest requiring cardiopulmonary resuscitation. The risk of cardiac arrest similarly increased as the number of intubation attempts increased. The overall risk was minimal (0.7%) with 1 or 2 attempts versus 11% for more than 2 attempts (a weighted average of 10% among those requiring 3 attempts and 12.5% requiring 4 or more attempts).
| Discussion |
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The ASA Task Force on the Management of the Difficult Airway has put forth the recommendation, based on consensus opinion of their expert consultants and not evidence-based medical data, to limit conventional intubation attempts to three to reduce airway trauma, swelling, and patient injury (9,10). However, to this end, there has been little clinical information offered to support, contest, or refute this airway management viewpoint. Moreover, the extent of penetration of the Guidelines into clinical practice in the OR as well as the remote location under emergency circumstances remains unreported.
This practice analysis provides evidence that the rate of hypoxemia, esophageal intubation, regurgitation, aspiration, bradycardia, and cardiac arrest accelerated beyond two intubation attempts. These findings lend support to the recommendation of limiting intubation attempts to three conventional attempts, albeit for emergency airway management services provided in the remote location, because of the impressive increase in airway-related and hemodynamic critical events. The considerable increase of complications between two and three attempts may warrant further refinement of the recommendation of limiting attempts to three, and perhaps emphasize that alternative airway techniques and the use of accessory devices may better serve the patient if considered even earlier in the process of securing the airway. However, this data review does not provide any evidence that aborting conventional laryngoscopy and intubation after three attempts in lieu of an accessory airway device or alternative airway rescue technique, will provide any patient benefit or improve the level of patient safety. Intuitively, incorporation of such a device or technique may decrease the incidence of complications, but the design of this practice review does not address this important airway management issue.
Several factors that the Guidelines have attempted to address but may still hamper the intubators ability to secure the airway may include the pursuit of conventional laryngoscopy on a repetitive basis at the exclusion of other methods by the individual, multiple personnel attempting intubation by conventional methods in a repetitive fashion, the relative lack of confidence, cognitive skills, or lack of experience with advanced rescue techniques, and the lack of immediate accessibility to advanced airway equipment. Based on the findings of this practice analysis, laryngoscopy on a repetitive basis, using three or more attempts as a reference basis, is beleaguered by patient morbidity and possible life-threatening critical events. Although the question regarding the value of pursuing the use of an advanced technique after three attempts was not addressed, the evidence suggesting the potential for a marked increase in airway-related and hemodynamic critical events when more than two attempts are required should encourage one to more timely pursue incorporation of the ASA recommendation of nonemergency and emergency pathway rescue options.
The limitations of this database include the reliance on personnel to accurately complete the questionnaire for submission to the database and may have benefited by a sampling of questionnaires by an independent, neutral observer rated to validate the accuracy of the self-report system. Furthermore, consideration should be given to the stressful, emergent, and dire circumstances in which the airway procedures were performed and the subsequent potential to underestimate and therefore underreport the number of intubation attempts or complications. Although the author reviewed each questionnaire and made every attempt to confirm the documented data with the physician, nurses, and support staff, a major concern with any spontaneous reporting system is underreporting of adverse events and the subsequent effect on the true numerator and the denominator of actual cases. Sanborn et al. (16) and others (1719) have suggested that voluntary reporting of undesirable anesthesia clinical events is strikingly infrequent. A portion of the questionnaires that were excluded because of illegibility or incomplete documentation and a number of patient encounters that failed to generate a submitted questionnaire are additional limitations of this reporting vehicle.
The primary focus of the ASA Guidelines is the management of the difficult airway encountered during administration of anesthesia and tracheal intubation. The ASA, however, acknowledges that some aspects of the Guidelines may be relevant in other clinical contexts (9,10). This data review provides substantial evidence that the incidence of airway and hemodynamic complications distinctly increase beyond two laryngoscopic attempts during emergency airway management in the remote location. Therefore, adapting the recommendation put forth by the ASA Guidelines on the Management of the Difficult Airway to limit intubation attempts to three seems warranted in emergency airway management outside the confines of the OR. This database did not investigate the clinical utility of accessory airway devices or advanced rescue techniques nor any improvement in the degree of safety we may offer to our patients when conventional methods prove difficult or unsuccessful.
This practice analysis and its findings prompt anesthesia personnel to rethink their approach to the elective and emergency management of the airway for the promotion of patient safety. The development of a secondary or backup airway management approach combined with the timely incorporation of rescue options in airway management strategy, although not proven, may be prudent toward improving the delivery of airway care for our patients. Moreover, this information has vast implications for the education and training of our anesthesia and nonanesthesia colleagues who are responsible for airway management outside the OR under the demands of an urgent or emergent situation and should serve as a motivation for rethinking his or her approach to airway management in the promotion of patient safety.
| Acknowledgments |
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| References |
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