Supraglottic Airway Versus Endotracheal Tube During Interventional Pulmonary Procedures

A Retrospective Study

Kyle M. Behrens; Richard E. Galgon

Disclosures

BMC Anesthesiol. 2019;19(196) 

In This Article

Discussion

The main finding of this study is that usage of SGAs for IP procedures can be highly successful with a low conversion rate to ETT when used in appropriately selected patients. Secondarily, when SGAs are used for IP procedures in our institution, the avoidance of NMBDs and the potential for consequent residual paralysis in a patient population that may have significant underlying pulmonary co-morbidities is achieved.

With the advancement of therapeutic and interventional procedures in the field of IP in recent years, there has been limited literature showing the usage and successfulness of SGAs compared to ETTs in anesthetized patients. Previously, Du Plessis et al found that during 140 adult patients undergoing fiberoptic bronchoscopy with general anesthesia using an SGA, only one patient required tracheal intubation due to laryngospasms, a conversion rate of 0.7%.[7] In a different retrospective study of 200 patients having underwent awake diagnostic bronchoscopies, use of an SGA facilitated successful bronchoscopies in every patient except one, where device placement was not tolerated.[8] Finally, in a recent publication by Schmutz et al, an SGA failure rate was found to be 3.1% in 132 patients that underwent transbronchial lung cryobiopsy, which the authors attributed to impossible placement of SGA (n = 1), high oropharyngeal leakage (n = 1), massive endobronchial bleeding (n = 1), and acute right heart failure requiring resuscitation (n = 1).[9] In our study, which includes a broader range of IP procedures, we found similar success in the use of SGAs for airway maintenance during general anesthesia.

Previous authors have discussed some advantages of SGA use during fiberoptic bronchoscopy under general anesthesia.[10] Beyond the use of decreased NMBDs use, advantages of using an SGA over an ETT for IP procedures based on clinical experience includes easier placement, examination of glottis and upper trachea, easier device placement including bronchoscope, lighter depth of anesthesia requirement, and smoother emergence. Additionally, based on our experience, we suggest several ideal features of SGAs for IP procedures. First, an SGA with a good oropharyngeal seal and stable fit enables positive pressure ventilation when needed at a higher airway pressure and may be less prone to dislodgement. Second, an SGA with a relatively short, straight, and large internal diameter air tube reduces resistance to bronchoscopic device movements, facilitating the IP procedure. Third, an SGA with a built-in bite block protects the bronchoscopic equipment from damage due to potential patient biting during the procedure. Finally, an SGA with a gastric channel enables decompression of a patient's stomach if desired, and also provides a means to reseat a dislodged SGA over an orogastric tube if left in situ.

Although our study provides evidence to support the use of SGAs for IP procedures, it is not without limitations. First, several different types of SGAs (Ambu® AuraStratight™, Ambu® AuraFlex™, LMA® Supreme™, LMA® ProSeal™, i-gel®, and air-Q®) were in use in our institution during the study period, and the specific SGA used for each case was not routinely recorded in the chart. Therefore, we cannot ascribe any success to a particular device. During the last two years of the study period, however, it is known that the i-gel® (over the Ambu® AuraStraight™) started to be used routinely for IP procedures, and continues to enjoy predominant use today, as it incorporates many of the ideal features noted above. Second, our study is a retrospective study, which can suffer from selection biases, variations in intra-operative management techniques, and missing data specifics, amongst others. It can be noted that at the time of these procedures patient characteristics, previous anesthesia and surgical experience, and local culture may have led to the anesthesiologist preferentially using one airway device over the others. The results of our study also do not show a correlation between airway device selection and general anesthesia maintenance (i.e. inhalational versus total intravenous anesthesia). Although prior reports indicate some advantages to total intravenous anesthesia, the majority of IP procedures at our institution continue to be performed using inhalation anesthesia due to attending anesthesiologist preferences.[11] Finally, two main modes of ventilation were used during the study period. For patients in the ETT group, the most common mode of ventilation was mandatory volume control ventilation (VCV) (56%), followed by mandatory pressure control ventilation (PCV) (39%). In the SGA group, the most common primary mode of ventilation was mandatory PCV (50%), followed by mandatory VCV (22%). Less commonly in both groups, patients were intermittently managed with other modes of ventilation. Specific ventilator parameters were not recorded in the database. Generally during the procedure, a standard bronchoscope with a sideport connection was placed on the proximal end of airway device facilitating passage of the bronchoscope into the patient's trachea and pulmonary tree. Patient ventilation and oxygenation was monitored using end-tidal carbon dioxide and pulse oximetry. If inadequate ventilation or oxygenation was a concern, the anesthesiologist communicated to the interventionalist to halt the procedure and withdrawal the bronchoscope to allow for collection of adequate monitor data. Adjustments in oxygen delivery and/or ventilation parameters were then made. Operating room pollution from inhalation agents was controlled using a standard gas scavenger system. Anesthesia providers who were uncomfortable with the performance of the SGA during the procedure due to air leak, exchanged the device for an ETT. This occurred in 0.4% of patients whose airways were managed with an SGA. We would like to acknowledge that high frequency jet ventilation has been commonly used during interventional pulmonology procedures at other institutions, however, this was not a mode of ventilation available at our institution and was not used during the study period. Nonetheless, despite the limitations of our study, our study is the largest study on the topic, and we believe the results provide support for the use of SGAs for airway maintenance during IP procedures, particularly given the limited availability of other data.

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