The Indian Anaesthetists’ Forum

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 20  |  Issue : 2  |  Page : 70--75

Predictability of airway evaluation indices in diabetic and nondiabetic patients requiring general anesthesia with endotracheal intubation


Ravindra Kute1, Rajendra Gosavi1, Prashant Bhaleker2, Deepak Phalgune3,  
1 Department of Anaesthesia, Poona Hospital and Research Centre, Pune, Maharashtra, India
2 Department of Anaesthesia, BJ Government Medical College and Sassoon General Hospitals, Pune, Maharashtra, India
3 Department of Research, Poona Hospital and Research Centre, Pune, Maharashtra, India

Correspondence Address:
Dr. Deepak Phalgune
18/27, Bharat Kunj - 1, Erandawane, Pune - 411 038, Maharashtra
India

Abstract

Introduction: Difficult airway management (intubation and/or ventilation) results in significant morbidity and mortality. In the present study, we evaluated various clinical parameters of airway assessment and their ability to predict difficult laryngoscopy and intubation in patients with diabetes mellitus (DM) compared to nondiabetic individuals. Methods: In this prospective comparative study, we enrolled an equal number of 110 patients in DM group and non-DM group. Patients were examined for body mass index (BMI), Modified Mallampati class (MMC), mouth opening, neck extension (NE), mobility of mandible by upper lip bite test, thyromental distance (TMD), collar size, palm print sign, and prayer sign. Primary outcome measure was Cormack and Lehane's grading on direct laryngoscopy. The comparison of quantitative and qualitative variables between the groups was done using unpaired Student's “t”-test and Chi-square test, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value of each test were done. Results: In DM patients, sensitivity was highest for MMC followed by prayer sign, whereas specificity was highest for palm print, followed by TMD, BMI, prayer sign, and other predictors. In non-DM individuals, sensitivity was highest for MMC whereas specificity was highest for prayer sign, followed by TMD, palm print and NE, and other predictors. Conclusions: In DM patients, sensitivity and specificity was highest for MMC and palm print, respectively. In non-DM individuals, sensitivity was highest for MMC whereas specificity was highest for prayer sign. A combination of tests may predict difficult laryngoscopy.



How to cite this article:
Kute R, Gosavi R, Bhaleker P, Phalgune D. Predictability of airway evaluation indices in diabetic and nondiabetic patients requiring general anesthesia with endotracheal intubation.Indian Anaesth Forum 2019;20:70-75


How to cite this URL:
Kute R, Gosavi R, Bhaleker P, Phalgune D. Predictability of airway evaluation indices in diabetic and nondiabetic patients requiring general anesthesia with endotracheal intubation. Indian Anaesth Forum [serial online] 2019 [cited 2019 Dec 14 ];20:70-75
Available from: http://www.theiaforum.org/text.asp?2019/20/2/70/265639


Full Text



 Introduction



Difficult tracheal intubation accounts for 17% of respiratory-related injuries and results in significant morbidity.[1] It is estimated that the inability to successfully manage difficult airway has been responsible for 30% of deaths attributed to anesthesia.[2] The incidence of difficult and failed intubation is reported to be 1%–3.6% and 0.05%–0.3%, respectively.[3] Many clinical indices have been devised to anticipate difficult airway preoperatively, commonly used are Modified Mallampati class (MMC), Thyromental distance (TMD), and neck extension (NE). Unfortunately, most of these have low sensitivity and specificity.

Diabetes mellitus (DM) is the most common endocrine disorder encountered, and almost 50% of DM patients undergo surgery for various reasons during their life period.[4] The incidence of difficult intubation in DM patients is higher than in normal population.[3],[5],[6] This is due to nonenzymatic glycosylation of collagen and its deposition in joints resulting in limited joint mobility syndrome. In long-standing DM due to the involvement of atlanto-occipital joint, inadequate extension of head and neck during laryngoscopy leads to difficult intubation.[3] In the present study, an attempt was made to evaluate various clinical parameters of airway assessment and their ability to predict difficult laryngoscopy and intubation in DM patients as compared to non-DM individuals.

 Methods



This prospective comparative study was conducted between April 2016 and September 2017. After approval from the scientific advisory committee and institutional ethics committee, written informed consent was obtained from all patients. Patients aged 18–65 years of either sex having DM for more than 5 years or without DM posted for surgery under general anesthesia, requiring endotracheal intubation were included. Patients with obvious anatomical abnormality (congenital, traumatic, and postsurgical) of face, neck, palate, and hands, patients with the previous history of difficult intubation and coexisting factors such as rheumatoid arthritis, large thyroid, airway trauma, and patients posted for emergency surgeries were excluded from this study.

The study was conducted in two groups of patients – DM patients (Group D) and non-DM individuals (Group N) each having 110 patients. On the day before surgery, the patient was examined in the sitting position, and the following indices were checked.

Body mass index (BMI)MMCMouth openingNEMobility of mandible by upper lip bite test (ULBT)TMDCollar sizePalm print signPrayer sign.

MMC class was defined as follows:[7]

Class I: Visualization of the soft palate, fauces, uvula, anterior and the posterior pillarsClass II: Visualization of the soft palate, fauces, and uvulaClass III: Visualization of soft palate and base of uvulaClass IV: Only hard palate visible.

ULBT was graded as follows:[8]

Class I: Patient is able to raise the lower incisors above the vermilion lineClass II: Patient is able to bite the upper lip below the vermilion lineClass III: Patient is unable to bite the upper lip.

Atlanto-occipital joint extension/NE was graded as follows:[9]

The patient was asked to hold head erect, facing directly to the front. The patient was asked to extend the head maximally. The researcher estimated the angle traversed by the occlusal surface of upper teeth with a goniometer.

Grade I (Normal): >35°Grade II: 22°–34°Grade III: 12°–21°Grade IV: <12°.

TMD:[10]

The distance from the mentum to the thyroid notch while the patient's neck was fully extended was measured.

Palm print sign was graded as follows:[3]

The patient was made to sit; palm and fingers of the right hand were painted with blue ink, the patient then pressed the hand firmly against a white paper placed on a hard surface.

It was categorized as:

Grade 0: All the phalangeal areas are visibleGrade 1: Deficiency in the interphalangeal areas of the 4th and 5th digitsGrade 2: Deficiency in the interphalangeal areas of the 2nd to 5th digitsGrade 3: Only the tips of the digits are seen.

Prayer Sign:[11]

The patient was asked to bring both the palms together as “Namaste” and the sign was categorized as:

Positive: When there is a gap between the palmsNegative: When there is no gap between the palms.

Mouth opening:[12]

Normal: More than or equal to 2 large fingerbreadths or 4 cmRestricted: <2 large fingerbreadths or 4 cm.

On the day of surgery, dose of antidiabetic agents was withheld. Six hours of fasting was ensured. Morning fasting blood sugar was done, and an intravenous (IV) line was secured. To have comparable results, only experienced anesthesiologists (with 2 or more years of experience) were allowed to intubate the patient in our study.

In the operation theater, adequate IV access was confirmed. Standard monitoring was attached. Noninvasive blood pressure, pulse-oximeter, electrocardiogram, and end-tidal CO2(ET CO2) were monitored after intubation. Before induction of anesthesia, all patients were given IV glycopyrrolate 0.2 mg, IV midazolam 1 mg, and IV fentanyl 2 μg/kg. In all patients, anesthesia was induced with IV propofol 1.5–2.0 mg/kg followed by IV atracurium 0.5 mg/kg. Laryngoscopy was done after 3 min with the patient's head in morning air sniffing position using the standard appropriate sized Macintosh blade.

The laryngeal view was graded according to Cormack and Lehane (CL) as follows:[13]

Grade I – Visualization of the entire laryngeal apertureGrade II – Visualization of only posterior commissure of laryngeal apertureGrade III – Visualization of only epiglottisGrade IV – Visualization of just the soft palate.

Patient's trachea was intubated with an appropriate size of endotracheal tube, and correct placement of tube was confirmed by auscultation of chest and capnography. In case of difficulty, maneuvers and gadgets such as use of external laryngeal manipulations, change in position of the head, use of different size and type of laryngoscope blade, intubating bougie, intubation by a more experienced anesthesiologist was done.

Anesthesia was maintained using Sevoflurane (aiming for minimum alveolar concentration of 1) in Oxygen and Air (50:50) with controlled mechanical ventilation. ET CO2 was maintained between 30 and 35 mm of Hg. Supplemental doses of IV atracurium (0.1 mg/kg) were given as required.

Primary outcome measure was CL grading of laryngoscopy. Considering the power of 80% and Type I error of 5%, and on the basis of a previously reported trial,[14] the sample size required was 110 cases in each group.

Statistical analysis

Data collected were entered into Excel 2007 and analysis of data was done using Statistical Package for Social Sciences (SPSS) version 20, IBM Corp., Armonk, NY: USA. The comparison of quantitative variables between the groups such as mean age, mean BMI was done using unpaired Student's “t”-test, whereas the comparison of qualitative variables such as gender, MMC, mouth opening, NE, mobility of mandible by ULBT, TMD, collar size, palm print sign, and prayer sign was done using Chi-square test. The confidence limit for significance was fixed at 95% level with P < 0.05. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each test was done according to standard formulas.

 Results



The present research was undertaken to evaluate various clinical parameters of airway assessment and their ability to predict difficult laryngoscopy and intubation in 110 DM patients as compared to 110 non-DM individuals. There was no statistically significant difference between Group D and Group N in relation to mean age, gender, and mean BMI [Table 1]. The percentage of patients who had MMC Class III and IV, NE Grades III and IV, BMI >30 kg/m2, collar size >40 cm in males and >38 cm in females, palm print index Grades II and III, and prayers sign positive were significantly higher in Group D compared to Group N. There was no statistically significant difference in mouth opening, TMD, and ULBT grades between Groups D and N. The percentage of patients who had CL Grades III and IV were significantly higher in Group D compared to Group N [Table 2].{Table 1}{Table 2}

In both groups (Group D and Group N), the percentage of patients who had MMC Class III and IV, BMI >30 kg/m2, collar size (>40 cm in males and >38 cm in females), and prayers sign positive were significantly higher in CL Grades III and IV. In Group D, the percentage of patients who had NE Grades III and IV, and palm print index Grades II and III were significantly higher in CL Grades III and IV whereas in Group N, the percentage of patients who had mouth opening restricted, TMD ≤6 cm, and ULBT Grade III were significantly higher in CL Grades III and IV [Table 3].{Table 3}

In Group D patients, sensitivity was highest for MMC (78.7%) followed by prayer sign (72.3%) whereas specificity was highest for palm print sign (93.7%), followed by TMD (88.9%), BMI (87.3%), prayer sign (84.1%), mouth opening (82.5%), NE (82.5%), collar size (81.0%), and ULBT (76.2%) [Table 4]. In Group N patients, sensitivity was highest for MMC (72.7%) whereas specificity was highest for prayer sign (96.6%), followed by TMD (95.5%), palm print sign (94.3%), NE (94.3%), BMI (93.2%), mouth opening (93.2%), ULBT (90.9%), and collar size (88.6%) [Table 5].{Table 4}{Table 5}

 Discussion



The present study was conducted to evaluate various clinical parameters of airway assessment and their ability to predict difficult laryngoscopy and intubation. Various parameters such as BMI, MMC, mouth opening, NE, ULBT, TMD, collar size, palm print sign, and prayer sign were used. We assessed difficulty of intubation by difficult laryngoscopy as per CL grading.

We found that a strong correlation between DM and higher CL grading. In our study, 47 (42.7%) patients in Group D had CL Grades III or IV as compared to only 22 (20.0%) in N group. In DM patients, MMC Class III and IV, NE Grades III and IV, BMI >30 kg/m2, larger collar size (>40 cm in males and >38 cm in females), palm print index Grades II and III, and positive prayers sign had a positive association with CL Grades III and IV. In non-DM individuals, MMC Class III and IV, mouth opening restricted, BMI >30 kg/m2, larger collar size (>40 cm in males and >38 cm in females), TMD ≤6 cm, ULBT Grade III, and positive prayers sign had a positive association with CL Grades III and IV. The percentage of patients who had MMC Class III and IV, NE Grades III and IV, BMI >30 kg/m2, larger collar size (>40 cm in males and >38 cm in females), palm print index Grades II and III, and positive prayers sign were significantly higher in DM patients compared to non-DM individuals. In DM patients, sensitivity was highest for MMC (78.7%), whereas specificity was highest for palm print sign (93.7%). In non-DM individuals, sensitivity was highest for MMC (72.7%), whereas specificity was highest for prayer sign (96.6%).

Studies by Hogan et al.,[5] Reissell et al.,[6] Nadal et al.,[3] Vani et al.,[15] Hashim and Thomas[16] have reported 32%, 31%, 27%, 16%, and 27.1% incidence of difficult laryngoscopy respectively in DM patients. Hashim and Thomas[16] reported that palm print sign had a significant association with difficult intubation. Reissell et al.,[6] in 1990, concluded that the higher the palm print grade, the more difficult was the laryngoscopy (P < 0.001).

Baig and Khan[17] conducted a study to determine the accuracy of prayer's sign and MMC in predicting difficult endotracheal intubation in DM patients. They reported that prayer's sign had significantly lower accuracy, PPV and NPV than MMC. The sensitivity of prayer's sign was lower (29.6%) than MMC (79.3%) while specificity was similar.

Mahmoodpoor et al.[18] studied the sensitivity of palm print sign and MMC in the prediction of difficult intubation. Palm print sign had highest specificity (96.5%) and MMC had highest sensitivity (98.4%). They reported 8.9% incidence of difficult intubation, and there was a significant correlation between BMI and difficult intubation (P = 0.004).

George and Jacob[14] reported that palm print test was most sensitive (76.7%), followed by MMC (56%), prayer sign (54.5%), and NE grades (50%). They further reported that palm print test was most specific (89.3%), followed by MMC (61.9%), prayer sign (52.5%) and NE grades (48.8%). Erden et al.,[19] conducted a study in DM and non-DM patients wherein they reported that there was a statistically significant association of positive prayer's sign in DM patients (P = 0.0132).

Vani et al.,[15] reported that palm print sign was the most sensitive test (75%) followed by NE grades (62.5%), MMC (25%), and TMD (25%). However, TMD was most specific (95.2%) followed by MMC (90.5%), palm print sign (69%), and NE grades (61.9%). Mallampati et al.[20] reported that palm print test was 100% sensitive.

Shiga et al.,[21] in a meta-analysis, stated that specificity and sensitivity of each test in prediction of difficult intubation is not ideal, but if these tests are combined together, the specificity and sensitivity would significantly increase. Mehmoodpoor et al.,[18] also reported the utility of combination of multiple tests for predicting difficult intubation.

 Conclusions



In DM, palm print was the best single predictor of a difficult intubation, followed by TMD and BMI. In non-DM patients, Prayer sign, TMD and palm print were the best predictor of airway difficulty. Even though we have multiple tests to predict airway difficulty, no single test is full proof armamentarium for anesthesiologist. All have poor-to-moderate discriminative power when used alone. Combination of tests may add some incremental diagnostic value.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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