Investigación Científica y Tecnológica

Validation of the Clinical Usefulness of an Articulated Orotracheal Catheter in the Operating Room and Intensive Care

Efraín Riveros Pérez MD MSc.*

* Director del Departamento de Ciencias Clínicas de la Universidad de Boyacá. Coordinador de la Unidad de Cuidado Intensivo, Clínica de los Andes. Correspondencia: Diagonal 41 No. 17A-21, Tunja, Colombia. Correo electrónico: efrriveros@uniboyaca.edu.co

Recibido: febrero 17 de 2011. Enviado para modificaciones: abril 5 de 2011. Aceptado: mayo 18 de 2011.

SUMMARY

Objective. To assess the clinical usefulness of the articulated orotracheal catheter (AOC). Clinical scenario. Operating rooms of Clínica San Pedro Claver de Bogotá, between February and August 2007, operating rooms of Hospital Universitario Mayor de Bogotá, between September 2007 and July 2008, intensive care unit of Clínica Especializada de los Andes in Tunja, between September 2008 and April 2010.

Materials and methods. After designing a cross-sectional descriptive study, information of 71 patients was collected. Anesthesiologists filled 22 forms (30 %) and anesthesia residents filled 49 (70 %) of the forms, when using the articulated orotracheal catheter. AOC was included in the algorithm for airway management in both institutions. Afterwards a clinical analysis of its usefulness was performed.

Results. The orotracheal articulated catheter was successfully inserted in the trachea on the first attempt by the first physician in 70 of 71 patients (98.6 %). In only one case (1.4 %) was it impossible to introduce the catheter, and in another one the catheter was introduced but the orotracheal tube could not be slid into the trachea on the first attempt.

The success rate of the first physician was strongly influenced by the degree of difficulty of the direct laryngoscopy. On the first attempt of the second physician, both patients were successfully intubated.

In four patients (5.6 %), airway trauma was detected because of aspiration of bloody secretions from the orotracheal tube.

Conclusions. The articulated orotracheal catheter is highly effective to achieve orotracheal intubation, but it can produce minor airway trauma.

Key Words: Laryngoscopy, Intratracheal Intubation, Catheters, Trachea. (Source: MeSH, NLM).

INTRODUTION

The probability of the presentation of an unanticipated difficult airway is still a worrisome situation and a challenge for the physician who works in critical areas like the emergency room, operating room or intensive care unit (ICU). The literature reports an incidence of 3 % of difficult airway, and 0.05 % – 0.3 % of impossible airway in unplanned scenarios (1). The situation is even more complicated in situations in which there is not enough time nor conditions to assess adequately the airway, which can happen in cases of the emergency room or the intensive care unit.

In a systematic study of complications associated with the airway in the ICU, Schwartz (2) reported serious complications in a significant group of patients. Among the problems he found were difficult intubation (8 %), esophageal intubations (8 %) and pulmonary aspiration (4 %), with an associated mortality of 3 %. When facing this scenario and with constant concern from both national and international health authorities regarding the safety of the patient (3,4), it is necessary to carefully develop alternatives to deal with the airway in cases of critical illness and when there is a need of emergent access to the trachea. In this context, Riveros et al (5) developed a new element called articulated orotracheal catheter (AOC), which has received special attention in Colombia, and was awarded a prize of “Videos in anesthesia" by Organización Sanitas, in the year 2007.

The AOC is a device made of two hollow parts of polyvinyl chloride 14 French in diameter, each of 25 cm in length, and which are articulated between them with a distal element which contains a removable guide wire which allows easy introduction to the trachea. The distal element is articulated with the proximal and when the guide wire is removed it allows an orotracheal tube to be slid over of the assembled device (Figures 1, 2 and 3). This study tests the AOC in terms of clinical effectiveness.

MATERIALS AND METHODS

A cross-sectional descriptive study was designed which was approved by the ethics committee of the Clínica San Pedro Claver de Bogotá and of the Clínica Especializada de los Andes de Tunja. Financing was provided by these two institutions in an 80 and 20 % percent each respectively, after declaring the no of conflict of interest between the two.

In both institutions the AOC was included in the difficult airway algorithm, and the clinical decision to use it was not modified by the development of this study. Both anesthesiologists as well as operating room and intensive care unit personnel were informed about the study being performed. In the algorithm of both institutions, the AUC was considered as first option.

When the AOC was used, a form available in all of the operating rooms as well as intensive care unit was filled and deposited in a special folder. The information collected included data of the patients, time of experience of the anesthesiologist or resident, if a difficult airway was anticipated, as well as the grading of the laryngoscopic view using the modified Cormack-Lehane scale (6,7) (Grade I: most of the vocal chords visible; Grade 2a: posterior vocal chords visible; Grade 2b: only the arythenoid cartilage visible; Grade 3a: visible and “moveable” epiglottis; grade 3b: visible epiglottis but adhered to the posterior pharynx; and Grade 4: no part of the larynx visible).

The reasons of using the device were assessed, as well as the use of other techniques before the AOC, the signs of trachea location (tracheal ring “clicks”, cough, and no further progression of the catheter, among others), the number of attempts required to position the AOC, early trauma evidence and finally the success rate of sliding the tube over the AOC once in place. Another question was if in case of failure of the first attempt with advancing the AOC, a second physician had done another attempt and if it was successful.

The collected forms were reviewed to identify missing data and blank spaces, and when these were detected, the responsible physician was contacted to complete the missing information.

Statistical analysis: The software SPSS (Statistical Package for the Social Sciences) was used, and logistic regression was applied to determine the association between continuous variables (operator experience) and categorical variables (if the AOC was reshaped before insertion). A Chi square test was used to examine the influence of the laryngoscopic vision on the success rate of the catheter insertion.

RESULTS

73 patients were included. In two cases the missing data in the forms was impossible to reconstruct, so they were excluded from analysis leaving 71 patients in the study.

The characteristics of the patients and the years of experience of the physicians are shown in tables 1 and 2 respectively.

A difficult airway was anticipated in 23 patients (32 %).

The reasons of the anesthesiologists to use the AOC were diverse and are shown in table 3. As can be seen in this table, the most common causes of difficulty in approaching the airway are the same as the ones considered as reasons to choose the AOC.

Other methods different from AOC were used in 48 patients (68 %), as shown in table 4.

The best laryngoscopic view as described by the modified Cormack-Lehane scale are shown in table 5. There was an influence of the laryngoscopic view on the number of attempts (x² = 37.52 p < 0.0001).

The success rate for insertion of the AOC and the orotracheal tube sliding correctly was of 98.6%. In 1.4% of the cases (two patients), the intervention of a second physician was necessary and the success rate was 100 %. The signs of adequate tracheal location of the AOC are shown in table 6. Airway trauma was detected because of the aspiration of bloody tracheal secretions in 4 patients (5.6 %), of which all were successful cases of AOC insertion on the first attempt.

Lastly, table 7 shows the need to change the form of the guide wire of the AOC device before insertion according to the difficulty observed during laryngoscopy. It was concluded that the need to change the form of the guide wire was not related to the grading of the laryngoscopic vision (x² = 3.13 with 5 degrees of liberty and a p = 0.59) nor with the operator experience (p= 0.82).

DISCUSSION

This study shows a high success rate of insertion of the articulated orotracheal catheter and of intubation by sliding the tube over it. Cook described slightly lower rates (94 %) with the Eschmann bougie, which works similarly to the AOC (7). The difference in the rates of success in favor of the AOC may be related to its higher flexibility which allows the tube to fit better during the sliding process.

On the other hand the AOC offer advantages with respect to other similar devices in terms of airflow resistance because of its shorter length and a higher number of holes which allow the system of resistances to remain parallel (5).

The group of physicians who participated in the study were a heterogeneous population in terms of experience which permitted a realistic intervention whose results could be extrapolated to different institutions.

The Eschmann bougie is considered the gold standard of introducers (8), and even though a comparative study between the two devices has not been performed, in a study made in mannequins, the performance of both the Eschmann bougie as well as the Frova bougie were found to be similar or maybe inferior to the AOC.

The correlation found between the laryngoscopic vision, the difficulty of intubation and the number of attempts is expected. However, because of the high rate of success of the orotracheal articulated catheter, it appears as a possible solution in cases of the difficult airways.

On the other hand, the incidence of minor airway trauma, as observed in the study, is comparable to that described with direct laryngoscopy and conventional orotracheal intubation.

In this type of studies there is a high risk of selection bias. However in this case, the patients in both institutions were included after applying a difficult airway algorithm, which is based on internationally accepted objective assessment of the airway, so it was not possible that the AOC could be used outside the protocol, reducing the risk of selection bias. Naturally, it would have been ideal that the airway assessment be performed by a different anesthesiologist unaware of the study, but in practice it was impossible, as no anesthesiologist would approach the airway without personally assessing it.

A significant limitation of the study is that it does not compare the performance of the device with similar ones widely available as the Frova and Eschmann bougies.

On the other hand, it is necessary to refine the AOC design so that it can be produced in large quantities and be promoted for difficult airway management situations.

In terms of generalizing the results, it is clear that the sample size does not permit to issue an unequivocal recommendation of the use of the articulated orotracheal catheter, but do suggest that it could be considered as an alternative for difficult airway management in critical areas. It could possibly be useful in prehospital care, where more sophisticated devices are not available and the personnel may not have the same skills available in an institutional level where anesthesiologists are available 24 hours a day.

These results also encourage future research in difficult airway management and the development of algorithms.

REFERENCES

1. Benumof JL. Management of the difficult airway. With special emphasis on awake tracheal intubation. Anesthesiology 1991;75:1087-110.

2. Schwartz DE, Matthay MA, Cohen NH. Death and other complications of emergency airway management of critically ill adults: a prospective investigation of 297 tracheal intubations. Anesthesiology. 1995;82:367-76.

3. Chacko J. Raju HR, Singh MK, Mishra RC. Critical incidents in a multidisciplinary intensive care unit. Anesth. Intensive Care. 2007;35:382-86.

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6. Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia. 1984;39:1105-11.

7. Cook TM. A new practical classification of laryngeal view. Anaesthesia. 2000;55:274-9.

8. Hodzovic I, Latto IP, Wilkes AR, Hall JE, Mapleson WW. Evaluation of Frova, single-use intubation introducer, in a manikin. Comparison with Eschmann multiple-use introducer and Portex single-use introducer. Anaesthesia. 2004; 59: 811-6.