Intubation difficulty scale: anticipated best use

A Randomised Control Study Comparing C-MAC D-Blade Video Laryngoscope (Hyper Angulated Blade) and Macintosh Laryngoscope for Insertion of a Double-Lumen Tube in Patients Undergoing Elective Thoracotomy

Background

The use of a double-lumen endotracheal tube is one of the common anesthetic techniques for operations in the thoracic cavity. However, when compared to a single-lumen tube, placement of a double-lumen tube is technically more difficult as a result of which it takes more time to insert and is associated with more complications such as mucosal injury, hoarseness, and sore throat, even in patients with no anticipated airway difficulty. The CMAC D-blade that is usually used in patients with anticipated airway difficulty, could assist in smooth and quick placement of double-lumen tube (DLT) even in patients with no anticipated airway difficulty.

Aim of the Study

This study aimed to evaluate the effectiveness of the C-MAC D-blade in reducing the time taken to visualize the glottis and intubate patients with normal airway with a double-lumen tube.

Setting and Design

This was a prospective open-label randomized control trial in a tertiary hospital.

Materials and Methods

Seventy-three consenting adult patients with physical status classes I and II, as determined by the American Society of Anesthesiologists, scheduled to undergo elective thoracotomy, were randomly allocated to receive either C-MAC D-blade (Group D) or Macintosh blade (Group M). The primary objective was to compare the time taken for visualization of the glottis and intubation.

Statistical Analysis Used

Chi-square/Fisher's exact test and t-test were used for statistical analysis.

Results

Seventy-three patients were randomized (Group D = 36; Group M = 37). Time to visualize the glottic structures (4.56 ± 2.396 s vs. 7.27 ± 4.891 s, P = 0.01) was significantly better in Group D; however, the mean intubation time was comparable (55.92 ± 18.749 s vs. 51.08 ± 15.269 s, P = 0.61).

Conclusion

C-MAC D-blade videolaryngoscope offers a better glottic view and lesser time to visualize glottis when compared with the Macintosh laryngoscope. However, the time taken to insert the DLT after visualization was longer. We infer that there is no advantage in the routine use of C-MAC D-blade for DLT insertion in patients with no anticipated airway difficulty.

A randomized control led study comparing CMAC video laryngoscope and Macintosh laryngoscope for insertion of double lumen tube in patients undergoing elective thoracotomy

Background and Aims

Double lumen tube (DLT) insertion for isolation of lung during thoracic surgery is challenging and is associated with considerable airway trauma. The advent of video laryngoscopy has revolutionized the management of difficult airway. Use of video laryngoscopy may reduce the time to intubate for DLTs even in patients with normal airway.

Material and Methods

A total of 87 ASA 1-3 adults, scheduled to undergo elective thoracotomy, requiring a DLT were randomly allocated to videolaryngoscope (CMAC) arm or Macintosh laryngoscope arm. It was on open label study, and only the patient was blinded. The primary objective of this study was to compare the mean time taken for DLT intubation with CMAC (Mac 3) and Macintosh laryngoscope blade and the secondary objectives included the hemodynamic response to intubation, the level of difficulty using the intubation difficulty scale (IDS), and complications associated with intubation. Data was analysed using the statistical software SPSS (version 18.0).

Results

The time taken for intubation was not significantly different (42.8 ± 14.8 s for CMAC and 42.5 ± 11.5 s for Macintosh laryngoscope P -0.908). The CMAC video laryngoscope was associated with an improved laryngoscopy grade (Grade I in 81.8% with CMAC and in 46.5% with Macintosh), less pressure applied on the tongue, and less external laryngeal pressure required. Hemodynamic responses to intubation were similar in both groups.

Conclusion

Macintosh blade is as good as CMAC (mac 3) blade to facilitate DLT intubation in adult patients with no anticipated airway difficulty, however CMAC was superior as it offers better laryngoscopic view, needed less force, and fewer external laryngeal manipulations.

Preparation for and Management of “Failed” Laryngoscopy and/or Intubation

An airway manager’s primary objective is to provide a path to oxygenation. This can be achieved by means of a facemask, a supraglottic airway, or a tracheal tube. If one method fails, an alternative approach may avert hypoxia. We cannot always predict the difficulties with each of the methods, but these difficulties may be overcome by an alternative technique. Each unsuccessful attempt to maintain oxygenation is time lost and may incrementally increase the risk of hypoxia, trauma, and airway obstruction necessitating a surgical airway. We should strive to optimize each effort. Differentiation between failed laryngoscopy and failed intubation is important because the solutions differ. Failed facemask ventilation may be easily managed with an supraglottic airway or alternatively tracheal intubation. When alveolar ventilation cannot be achieved by facemask, supraglottic airway, or tracheal intubation, every anesthesiologist should be prepared to perform an emergency surgical airway to avert disaster.

Comparison of the Airtraq laryngoscope and the GlideScope for double-lumen tube intubation in patients with predicted normal airways: a prospective randomized trial

BACKGROUND

The Airtraq laryngoscope and the GlideScope are commonly used in many airway scenarios. However, their features have not been fully described for double-lumen tube intubation. A prospective randomized study was designed to compare their intubation performances in thoracic surgery patients.

METHODS

Seventy ASA physical status I and II patients with predicted normal airway were scheduled for thoracic surgeries with double-lumen tube intubation. They were randomly assigned to one of two groups and intubated with either the Airtraq laryngoscope (group A, n = 35) or the GlideScope (group G, n = 35). Airway assessments were performed prior to anesthesia, and all patients were induced with a standard anesthetic regimen. The Cormack-Lehane grades were initially evaluated with a Macintosh laryngoscope and subsequently with the group-specific laryngoscope before intubation. Intubation time was recorded as the primary outcome. The Cormack-Lehane grade, the success of the first intubation attempt, the intubation difficulty scales and ease of tube advancement were noted. Hemodynamic variables during intubation and incidence of post-operative sore throat were documented as well.

RESULTS

The intubation time of group A was shorter than that of group G (36.6 ± 20.2 s vs. 54.6 ± 25.7 s, p = 0.002). The Cormack-Lehane grade (I/II/III/IV) was significantly better in group A (33/2/0/0 vs. 28/7/0/0, p = 0.042). The mean arterial pressure and heart rate rose to higher levels during intubation with the GlideScope than with the Airtraq laryngoscope. The success of the first intubation attempt and the intubation difficulty scales were comparable between the two groups. The numbers of patients who experienced postoperative sore throat were similar (6 vs. 8) in the two groups.

CONCLUSIONS

Compared with the GlideScope, the specially designed Airtraq laryngoscope might be more suitable for double-lumen tube intubations in patients with predicted normal airway.

TRIAL REGISTRATION

www.chictr.org Identifier: ChiCTR-TRC-11001628.

A comparison of tracheal intubation using the Airtraq�or the Macintosh laryngoscope in routine airway management: a randomised, controlled clinical trial

The Airtraq laryngoscope is a novel single use tracheal intubation device. We compared the Airtraq with the Macintosh laryngoscope in patients deemed at low risk for difficult intubation in a randomised, controlled clinical trial. Sixty consenting patients presenting for surgery requiring tracheal intubation were randomly allocated to undergo intubation using a Macintosh (n = 30) or Airtraq (n = 30) laryngoscope. All patients were intubated by one of four anaesthetists experienced in the use of both laryngoscopes. No significant differences in demographic or airway variables were observed between the groups. All but one patient, in the Macintosh group, was successfully intubated on the first attempt. There was no difference between groups in the duration of intubation attempts. In comparison to the Macintosh laryngoscope, the Airtraq resulted in modest improvements in the intubation difficulty score, and in ease of use. Tracheal intubation with the Airtraq resulted in less alterations in heart rate. These findings demonstrate the utility of the Airtraq laryngoscope for tracheal intubation in low risk patients.

Prehospital standardization of medical airway management: incidence and risk factors of difficult airway

OBJECTIVES

The rate of difficult intubation in prehospital emergency medicine varies greatly among studies already published and depends on several factors. The authors' objective was to determine the rate of difficult intubations and to determine factors associated with prehospital difficult airways when a standard protocol for sedation and intubation was applied.

METHODS

This 30-month clinical, observational, prospective study was performed in a suburb of Paris, France (Val de Marne, population 1,300,000) by a prehospital emergency medical unit. Airway management for patients who needed tracheal intubation was standardized. The pharmacological procedure recommended rapid sequence intubation for patients with spontaneous cardiac activity. In cases of difficult, laryngoscopy-assisted intubation, a predefined algorithm was proposed. The Intubation Difficulty Score (IDS) was calculated for all patients requiring tracheal intubation, and factors associated with difficult intubation, defined by IDS of >5, were identified by using multivariate statistical analysis.

RESULTS

During the study period, 1,442 patients were included; 640 (44%) were in cardiorespiratory arrest, and 802 had a spontaneous cardiac activity. Deviation from the pharmacological and airway management procedures occurred in 1% of cases. When the predefined difficult airway management algorithm was followed, failure to intubate was encountered twice (0.1%). One hundred six (7.4%) patients had an IDS of >5, and 60 (4.1%) required first (n = 56) then second (n = 4) alternative techniques for tracheal intubation. Semirigid leaders allowed tracheal access in 93% of difficult-intubation patients. One patient required a prehospital cricothyroidotomy. Factors associated with difficult intubation were the following: a history of ear, nose, or throat neoplasia or surgery; obesity; facial trauma; the operator's status; and the operator's position.

CONCLUSIONS

If prehospital medical airway management is standardized and performed by trained operators, failure to intubate is rare (0.1%), and the incidence of difficult tracheal intubation is 7.4%, independent of cardiorespiratory status.

Evaluation of the airway and preparation for difficulty

Preoperative airway evaluation is essential to consider which is the best method of maintaining and protecting the airway during surgery and whether problems with airway management are likely. In general surgical patients, the prevalence of difficult intubation is low and tests have poor predictive power. This means that the patient may be evaluated as normal but prove to be difficult. The absence of reliable prediction in general surgical patients means that airway strategy holds the key to successful management. Where there are obvious abnormalities in the history, examination or imaging the preoperative evaluation will allow choice of the most appropriate airway strategy which may include preparation of the patient, assembling of alternative airway equipment, advice and help from a more senior or skilled anaesthetist or aid from a surgical colleague or assistant.

Difficult tracheal intubation is more common in obese than in lean patients

Whether tracheal intubation is more difficult in obese patients is debatable. We compared the incidence of difficult tracheal intubation in obese and lean patients by using a recently validated objective scale, the intubation difficulty scale (IDS). We studied 134 lean (body mass index, <30 kg/m2) and 129 obese (body mass index, >or=35 kg/m2) consecutive patients. The IDS scores, categorized as difficult intubation (IDS >or=>5) or not (IDS <5), and the patient data, including oxygen saturation (SpO2) while breathing oxygen, were compared between lean and obese patients. In addition, risk factors for difficult intubation were determined in obese patients. The IDS score was >or=5 in 3 lean and 20 obese patients (P = 0.0001). A Mallampati score of III-IV was the only independent risk factor for difficult intubation in obese patients (odds ratio, 12.51; 95% confidence interval, 2.01-77.81), but its specificity and positive predictive value were 62% and 29%, respectively. SpO2 values noted during intubation were (mean +/- SD) 99% +/- 1% (range, 91%-100%) and 95% +/- 8% (range, 50%-100%) in lean and obese patients, respectively (P < 0.0001). We conclude that difficult intubation is more common among obese than nonobese patients. None of the classic risk factors for difficult intubation was satisfactory in obese patients. The high risk of desaturation warrants studies to identify new predictors of difficult intubation in the obese.

IMPLICATIONS

We report a difficult intubation rate of 15.5% in obese patients and 2.2% in lean patients. None of the risk factors for difficult intubation described in the lean population was satisfactory in the obese patients. We also report a high risk of desaturation in obese patients with difficult intubation.

Difficult airway management in the emergency department

Most airway management in the emergency department is straightforward and readily accomplished by the emergency physician. The exact incidence of difficult intubations is difficult to discern from available evidence, but these are probably more frequent in the Emergency Department than in the operating room, given the urgent nature of the procedure and the lack of preparation of the patient population. A variety of adjuncts for airway management are available to assist in both intubation and ventilation. The utility of these adjuncts is detailed in this review, with emphasis on techniques most useful to the emergency physician.

Emergent airway management. Indications and methods in the face of confounding conditions

Optimal airway management requires an experienced caregiver, attention to detail, and knowledge of the patient's physiology. A variety of pharmacologic agents have proved useful in obtaining a secure airway and minimizing risk to the patient. Depending on the skills of the caregiver, oral intubation has become the preferred means of airway control in most patients. Advances in technique, equipment, and pharmacology have greatly improved the art of airway management; however, there is no substitute for an experienced clinician.