Ain-Shams Journal of Anaesthesiology

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 8  |  Issue : 2  |  Page : 173--178

Comparative study between a sensascope and a flexible fiberoptic in head and neck cancer surgeries with difficult airways


Emad G Saleh, Ekramy M Abdelghafar 
 Department of Anesthesia and Pain Management, National Cancer Institute, Cairo University, Cairo, Egypt

Correspondence Address:
Emad G Saleh
Department of Anesthesia and Pain Management, National Cancer Institute, Cairo University, Cairo
Egypt

Abstract

Background Many devices have been become widely available for managing difficult airways, including rigid fiberscopes and flexible fiberoptic bronchoscopes. The sensascope is different from the flexible fiberoptic in that it can be used with one hand (preferably the right hand) while the left hand is used to insert the laryngoscope as recommended by experienced users. The objective of this study was to evaluate the efficacy of a sensascope in the management of difficult airways in patients scheduled for head and neck cancer surgeries. Patients and methods This study was conducted at the National Cancer Institute on 60 patients. The patients were divided into two equal groups, group F (FOB) and group S (sensascopes), each comprising 30 patients. The following parameters were measured: patient characteristics including age, sex, weight, and ASA classification, airway assessment, hemodynamic changes, number of failures of intubation, duration of intubation, number of attempts, and complications that may occur during manipulation of the airway. Results The success rate of intubation and the number of failures were statistically comparable between the two groups. The mean time taken to complete successful intubation was significantly shorter in group F compared with group S. The number of patients successfully intubated at first attempt was significantly higher in group F than in group S. The number of patients successfully intubated at second attempt was significantly higher in group S than in group F. The number of patients who needed three attempts to be successfully intubated was statistically comparable between the two groups. There was statistically significant increase in pulse rate and mean arterial blood pressure immediately after successful intubation in group S compared with baseline and with group F. There was a significantly higher incidence of staining of the fiberscope blade with blood and transient change in voice in group S compared with group F. Conclusion The sensascope can be a valuable aid in the management of difficult intubation in a spontaneously breathing anesthetized patient, and should be added to backup devices in the event of difficult intubation.



How to cite this article:
Saleh EG, Abdelghafar EM. Comparative study between a sensascope and a flexible fiberoptic in head and neck cancer surgeries with difficult airways.Ain-Shams J Anaesthesiol 2015;8:173-178


How to cite this URL:
Saleh EG, Abdelghafar EM. Comparative study between a sensascope and a flexible fiberoptic in head and neck cancer surgeries with difficult airways. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2019 Sep 21 ];8:173-178
Available from: http://www.asja.eg.net/text.asp?2015/8/2/173/156671


Full Text

 Introduction



Difficult or failed tracheal intubation is a crucial cause of increased morbidity and mortality during induction of general anesthesia [1] . Airway assessment methods have been implemented to detect patients who are at risk for difficult intubation in anesthetic practice [2],[3] .

In most patients conventional direct laryngoscopy is considered to be the best method for intubation during anesthesia and surgery [1],[2] . However, conventional direct laryngoscopy has been shown to fail in about 5% of patients with difficult airways and this leads to mortality and severe morbidity [4] .

Many devices have become widely available for managing difficult airways, including rigid optical stylet, the augustine scope, light wands, intubation laryngeal mask airway, Bullard laryngoscope, visualized endotracheal tube, and the rigid fiberscope and flexible fiberoptic bronchoscopes (FOBs) [5] .

Although the flexible FOB is considered the gold standard in managing predicted difficult airways, hours of training is needed to optimize control of the FOB [6],[7] .

The sensascope (CH-8816 Hirrel; Acutronic Medical Systems AG, Switzerland) is a hybrid video-equipped instrument with a 40-cm-long rigid shaft with a sigmoid shape that ends with a 3 cm long steerable flexible distal end. The tip is controlled with a lever at the handle of the device. It is fitted with a miniaturized CCd camera. The endoscope has a port for the light source and an eyepiece that can be used without a monitor, or it can be connected to the camera of the monitor and viewed by everybody.

The sensascope is different from the flexible fiberoptic in that it can be used with one hand (preferably the right hand) while the left hand is used to insert the laryngoscope, as recommended by experienced users [8] .

The aim of this study was to evaluate the efficacy of the sensascope in the management of difficult airways in patients scheduled for head and neck cancer surgery.

 Patients and methods



Before starting the study, an instructor experienced in the use of the sensascope trained us on a mannequin to perform intubations with the sensascope. After that we tried using the sensascope in patients with normal airways. After mastering the technique of using the sensascope on patients with normal airways, approval from the medical ethical committee and patient consent for the procedure and publication were taken to perform the study on 60 head and neck cancer patients of both sexes at the National Cancer Institute, Cairo University, from April 2011 to November 2013. All patients were scheduled for elective head and neck surgeries requiring endotracheal intubation. All patients were subjected to preoperative clinical and airway assessment and routine laboratory investigations. All patients in the preoperative room received atropine at 0.01 mg/kg to help dry oropharyngeal secretion and facilitate intubation; no sedation was given fearing airway obstruction and oxygen desaturation during patient transfer to the operating room.

The patients were divided into two equal groups, group F (FOB) and group S (sensascopes), each comprising 30 patients. The order of patients intubated using the FOB or the sensascope was decided randomly by means of computer-generated tables.

Exclusion criteria

Age less than 18 years.Requirement for an endotracheal tube of an internal diameter smaller than 6.0 mm.Difficult ventilation (when oxygenation cannot be maintained by mask ventilation).Presence of cervical spine instability.On arrival at the operating room, we applied noninvasive monitoring (blood pressure, heart rate, and arterial oxygen saturation), and baseline measurements were taken. The patient was first preoxygenated for 5 min and then local anesthesia was applied to the oral and pharyngeal mucosa using lidocaine 10% spray. The trachea was anesthetized by injecting 3 ml lidocaine through the cricothyroid membrane. The patient was then allowed to take deep breaths of sevoflurane until he or she was deeply anesthetized without loss of spontaneous breathing.

In the F group, the fiberscope (porta view LF-GP; Olympus Optical Co. Ltd, Tokyo, Japan) was attached to a video camera and focus with white balance was manipulated until optimum view was achieved. A trained anesthesiologist using direct laryngoscopy lifted the tongue base and opened the oropharyngeal airway. The fiberscope was introduced gently until the vocal cord could be seen. If there was coughing or bucking lidocaine was injected through the sideway of the fiberscope. The fiberscope was then introduced until 2 cm above the carina, where the tube was railroaded into the trachea under vision [9] .

In the S group also the sensascope was attached to a video camera monitor (video monitor) and focus was manipulated until optimum view was achieved. The sensascope (CH-88.6 Hirzel; Acutronic Medical Systems AG) is operated with the right hand; the thumb rests on the lever to lower the flexible part by 3 cm. The operator uses the direct laryngoscope with the left hand to elevate the tongue and open the oropharynx, leaving a free space for introduction of the sensascope. The sensascope is slowly introduced into the mouth perpendicularly in a sagittal plane with the tip close to the upper incisors [8] .

Once the upper incisors are traversed the video monitor is observed to view the uvula appearing in the midline of the image. The sensascope is then slowly advanced along the palate straight into the uvula. After passing the uvula, the tip is elevated by pulling the lever until the glottic opening appears on the screen. As the sensascope is sigmoid in shape, further advancement into the glottis is achieved by rotation of the handle in cephalad direction. This allows its distal curvature to move easily around the tongue base when the device is rotated in this way [10] .

Once the vocal cords have been passed, the tip of the endoscope points toward the anterior wall of the trachea, and it has to be bent downward by elevating the lever with the thumb. This produces an axial view down the trachea, where the endoscope should be further advanced by continuing the mentioned rotation.

Once the tip arrives just above the carina the direct laryngoscope is withdrawn, leaving the left hand free to manage the intubations. The endoscope is held firmly by the right hand and the left hand is used to railroad the tube into its final position, confirmed by the endoscopic view. The sensascope is then easily withdrawn with the right hand while the left hand firmly holds the tube in position [8] .

The following parameters were measured by the anesthesiologist who did not participate in the procedures:

Patient's characteristic including age, sex, weight, and ASA classification.Airway assessment, including cause of difficulty, mouth opening, thyromental distance, Mallampati classification.Hemodynamic changes (heart rate and mean arterial blood pressure) before intubation and just after successful intubation.Number of failures of intubation.Duration of intubation: The videos of all endoscopies were converted into video files and stored in a computer connected with a telepack. The duration of endoscopy was measured by replaying the video files after completion of the procedure.Number of attempts (not more than three attempts): After failure of the third attempt the procedure is considered failed.Complications including hypoxia, staining of the fiberscope blade with blood, and transient change of voice are assessed by the anesthesiologist who is blinded to the technique.Statistical analysis

We intended to perform sample size calculation but because of unavailability of the sensascope at our National Cancer Institute we were obliged to rent it. We did not perform sample size calculation and decided to include 30 patients in each group, as the first clinical experience of tracheal intubation with a sensascope was on 32 patients in the study conducted by Biro et al. [8] .

The data were collected, coded, and analyzed using SPSS version 16.0 (Chicago, IL, USA). The data on the success rate of tracheal intubation and number of intubation attempts were compared between the two groups using the χ2 -test. The mean duration of intubation, mean pulse rate, mean arterial blood pressure, and mean characteristics such as mean age, weight, and height were compared with an unpaired Student t-test and presented as mean and SD.

The incidence of adverse effects in the form of hypoxemia during intubation, staining of the fiberscope blade with blood, and hoarseness of voice was compared using the χ2 -test and the Mann-Whitney U-test. P values less than 0.05 were considered statistically significant.

 Results



In terms of the demographic characteristics of all patients in the study, the mean age, mean weight, sex, ASA classification, and types of surgeries were comparable in the two groups, with no statistically significant differences between them ([Table 1] and [Table 2]).{Table 1}{Table 2}

There were no statistically significant differences between the two groups as regards mouth opening, thyromental distance, and Mallampati classification, as shown in [Table 3].{Table 3}

There was no significant difference in mean heart rate at baseline in the two groups, and the mean heart rate immediately after successful intubations was significantly higher in group S compared with baseline and with group F ([Table 4]).{Table 4}

There was a statistically significant increase in mean arterial blood pressure immediately after successful intubation in group S compared with baseline and with group F ([Table 5]).{Table 5}

The success rate of intubation and number of failures were statistically insignificant between the two groups.

The mean time taken to complete successful intubation was significantly shorter in group F compared with group S ([Table 6]).{Table 6}

The number of patients successfully intubated at first attempt was statistically significantly higher in group F compared with group S. The number of patients successfully intubated at second attempt was significantly higher in group S compared with group F. The number of patients who needed three attempts to be successfully intubated was statistically insignificant between the two groups ([Table 7]).{Table 7}

There was a statistically significantly higher incidence of staining of the fiberscope blade with blood and transient change in voice in group S compared with group F. The incidence of hypoxemia during intubation in group S was higher than that in group F but was statistically insignificant ([Table 8]).{Table 8}

 Discussion



In patients with difficult airways, including those suffering from head and neck malignancies, it may be impossible to intubate using a direct laryngoscope.

Although the flexible fiberoptic is considered the gold standard of all methods, it is not suitable in emergency cases when airway difficulty occurs unexpectedly [11] .

The use of rigid fiberscopes in the management of difficult airways was established recently. Recent studies have recommended the use of a sensascope in the management of difficult airways, either predicted or unpredicted [12],[13],[14] . As we frequently encounter patients with head and neck malignancy in our institute, with a high possibility of difficult or even impossible intubation with conventional direct laryngoscopy, we studied the use of a sensascope, in comparison with a flexible fiberscope, in the management of those patients with difficult intubation. In this study the time needed for intubation with a flexible fiberscope was significantly shorter than the time needed with a sensascope, demonstrating that intubations were easy and faster with a flexible fiberscope than with a sensascope. This is attributed to the fact that most patients have a disturbed anatomy that needs more flexibility and fine adjustment of the movement of the fiberscope. This could be easily achieved with the flexible fiberscope, whereas the sensascope, although it is S shaped and has a flexible lower 3 cm end, was difficult to manipulate in this disturbed anatomy and time was required to explore the airway and reach the vocal cords. Although the direct laryngoscope was used by the operator in the sensascope group and by another person in the flexible fiberscope group, it did not affect the procedure of intubation, as the person managing the direct laryngoscope in the flexible fiberscope group was trained on both the direct and flexible fiberscope and followed the video monitor and manipulated the direct laryngoscope according to the situation of the airways and as per the operator's verbal communication. This, together with recording of the whole procedure with a video-processing system with a camera attached to the scope eyepieces, will reduce human error. In our preliminary study on 40 patients with normal airways, we used many techniques to try to open the airway and facilitate intubation with a fiberscope, such as jaw thrust, tongue traction, or using a direct laryngoscope. It was proved that a direct laryngoscope is the best method to open the airway and facilitate fiberscope intubation and therefore this method was used in all patients.

Hagberg and Westhofen [15] also reported a useful two-person technique using fiberoptics in combination with a direct laryngoscope for extubation/reintubation in two ICU patients with known difficult airways.

A study was conducted by Biro et al. [8] using a sensascope on 200 patients with varied degrees of difficulty on using a direct laryngoscope. They postulated that the intubation technique using the sensascope contains familiar features like those of a conventional laryngoscope and steering techniques like those of fiberscopes. They reported that the learning curve for naive users reached a median intubation time of 20 s after four attempts.

In contrast to the study conducted by Biro and colleagues, our study results showed that the mean time of intubation was 84 s. This could be related to the fact that most patients in the study by Biro had a normal anatomy, whereas our patients had difficult airways.

In another study conducted on 13 patients with difficult airways, with indication for awake tracheal intubation using a sensascope, the patients exhibited intubation times ranging from 28 to 300 s. That study was conducted on sedated patients on remifentanyl infusion, whereas our study was conducted on anesthetized spontaneously breathing patients on sevoflurane [10] .

There was significant difference in the time of intubation between the two groups, as well in the failure rate of intubation. Failure of intubation occurred in three patients of the sensascope group: two were intubated using the flexible fiberoptic and one underwent tracheostomy. The two cases of failure in the flexible fiberoptic group underwent tracheostomy as they had a large necrotic mass at the base of the tongue affecting the epiglottis and disturbing the laryngeal view, with profound bleeding when touched by the direct laryngoscope. In a study by Grief R [10] 13 patients with difficult airways were intubated with the sensascope without any failure, showing slightly different results from ours. The difference could be attributed to the fact that they used fewer cases than in our study or because the quality of patients was different. Another study on 200 patients under complete general anesthesia with muscle relaxants [8] showed that all patients were successfully intubated using the sensascope. We could relate the difference between our study and that of Biro to the fact that most of their patients had a normal airway and were completely relaxed under general anesthesia [8],[10] .

With regard to the number of attempts to reach the vocal cards, 85% of patients in group F were intubated in the first attempt, and 96% of patients were intubated in the second attempt. In contrast, 55% of patients in group S were intubated in the first attempt and 89% in the second attempt. We relate the significant difference between the groups to the greater flexibility of the flexible fiberoptic in group F and the presence of sideway suction that allowed us to overcome the presence of secretion or blood during the procedure of intubation. In the case of the sensascope, in contrast, we were obliged to suction the airway using external suction when there was copious secretion or blood as it has no suctioning sideway. In the study by Biro and colleagues easy intubation with the sensascope was achieved with only one attempt in 188 of 200 cases (94%). In the remaining 12 cases correct tracheal tube position was finally achieved but it took up to 118 s [8] .

Because of the longer time and more attempts in group S than in group F, the sensascope was more stained by blood in comparison with the fiberoptic group. Also the transient change of voice was more pronounced in the sensascope group than in the fiberoptic group. This could be related to the trauma that may have occurred, either by the sensascope itself or by the direct laryngoscope during manipulation in group S.

The stress response during intubation was compared between the two groups on the basis of hemodynamic changes (mean arterial blood pressure and pulse rate). It showed significant increase in mean arterial blood pressure and pulse rate in the sensascope group 5 min after successful intubation and after more attempts, because of the longer time and more manipulations to the airways ([Figure 1] [Figure 2] [Figure 3]).{Figure 1}{Figure 2}{Figure 3}

 Conclusion



From this study we can conclude that the sensascope can be a valuable aid in the management of difficult intubation in spontaneously breathing anesthetized patients. We recommend its usage in anesthetized patients with muscle relaxant to decrease the incidence of airway trauma and suggest that it be added to backup devices during difficult intubation.

 Acknowledgements



Conflicts of interest

None declared.

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