Dicult Tracheal Intubation is More Common among Hazara Tribe and Females in Afghanistan

Introduction: Airway management is a considerable challenge for anesthesiologists. The diagnostic value of the screening tests differs in various studies. This is due to the variety in the incidence of intubation, insucient statistical power, and different test inception. To have a safe intubation, it is essential to perform a precise preoperative airway assessment. However, there is still an argument about which tests and anatomical landmarks would be the best predictors. Objective: This study is aimed to determine the best predictors and socio-demographic characteristics of dicult intubation among adult patients scheduled for elective surgeries under general anesthesia in Aliabad Teaching Hospital, Kabul, Afghanistan. Method: A total of 341 patients were selected based on consecutive sampling method. Informed consent forms were obtained before inclusion in the study. Data were collected using a data collection form. Age, gender, ASA physical status and tribe were recorded for each participant. Airway assessment test was conducted before operation for additional consideration. Data were initially entered into an excel data sheet, and then exported to SPSS Statistics version 22 for analysis. Results: From a total of 341 patients, 193 (56.6%) were males and 148 (43.4%) were females. The mean age of the subjects was 36.98 ± 15.048 years. More than half (54.5%) of the study population were Tajiks. Hazara tribe, female patients, increasing age and systemic disease patients had more dicult intubation. We recognized that, Mallampati classes, mouth opening, thyromental distance, ability to prognath and neck mobility and size were associated with dicult intubation. Multiple logistic regression analysis of the associated factors determined that increase age, ability to prognath and mouth opening were independent predictors of dicult intubation. Conclusion: Female patients and Hazara tribe were found to have a signicant association with dicult intubation on bivariate analysis. Multiple logistic regression analysis determined that increase age, ability to prognath and mouth opening were independent predictors for dicult intubation.


Introduction
Airway management has been a remarkable contest for anesthesiologists. Endotracheal intubation is one of the recognized life threatening pillars in airway management during induction of general anesthesia while attempting to insert the endotracheal tube with the aid of laryngoscope (Andrade et al., 2018).The diagnostic value of screening tests differs in various studies. This is due to the variety in the incidence of intubation, insu cient statistical power, and different test inception. Differences in patient properties affected by origin may also affect the incidence of di cult intubation (Prakash et al., 2013).
Risk factors reported to be associated with di cult intubation are mouth opening less than 4 cm, thyromental distance less than 6 cm, Mallampati Class III or higher, neck mobility and size less than 35°and inability to advance the mandible. Almost all (98%) di cult intubations may be predicted by performing a thorough and careful assessment of the airways prior to surgery. However, many clinicians pay little consideration to this vital task and bound their investigation of the airway to a super cial examination of the mouth and teeth (Finucane et al., 2003, Combes et al., 2004. To have a safe intubation, it is essential to perform a precise preoperative airway assessment, but still there is an argument which tests and anatomical landmarks would be the best predictors (Moustafa et al., 2017).
Intubation Di culty Scale (IDS) score is a function of seven parameters, which result in a progressive and quantitative determination of intubation complexity. This score is calculated by the operator immediately after intubation. IDS score of = 0 represents easy intubation; IDS score of = 1-5 represents slight di cult intubation; IDS score of >5 represents moderate to major di cult intubation; and IDS score of = ∞ denotes impossible intubation (Garg and Dua, 2015). Di cult intubation is de ned as more than three attempts (IDS > 5) or more than 10 minutes using direct laryngoscopy to complete tracheal intubation (Prakash et al., 2013, Workeneh et al., 2017.The aim of this study was to nd out some best predictors of the preoperative airway assessment and identify socio-demographic characteristics of di cult intubation. This is the rst study of its type in Ali Abad Teaching Hospital, Kabul Afghanistan which attempts to provide a base-line data for future researches. Methods This is a cross-sectional study conducted in Aliabad Teaching Hospital (ATH), Kabul University of Medical Sciences, from October 2018 to January 2019. Patients who were scheduled for elective surgery under general anesthesia at Neurosurgery, Orthopedics, Urology and General surgery wards of ATH were chosen to participate in the study. A verbal brie ng was provided to introduce the objectives and methodology of the study. Once the participants agreed to take part in the study, they were asked to sign the informed consent form. The sample size estimation was based on the consecutive sampling a common practice is to select all cases which are available in a given period of time or to select a sample size based on a previous study (Omair, 2014).
Mallampati score, mouth opening, thyromental distance, ability to prognath, neck mobility and size were the independent variables. In order to collect information on the socio-demographic characteristics of the participants, a data collection sheet was designed and developed in by the principal researchers with the intention to cover all possible factors associated with di culty in intubation (Prakash et al., 2013, Garg and Dua, 2015, Wilson and Benumof, 1998). All patients above 18 years old, ASA physical status I, II or III, both gender who required general anesthesia and orotracheal intubation were included in the study.
However, Patients with facial abnormalities, both congenital and traumatic in whom airway assessment was not possible, patients undergoing emergency surgery, with a full stomach, tracheostomized, and those not receiving neuromuscular blocker were excluded from the study. Initial data was entered into an excel datasheet and then exported to IBM SPSS version 22 for windows for analysis. Simple bi-variable analysis was used to determine factors which are associated with di cult intubation. A p value of 0.05 was set as signi cance level at 95% con dence interval. The results were presented as crude odds ratios (OR C ) with 95% con dence intervals (CI). In order to nd out indicators which made signi cant independent contributions to the preoperative predictors for IDS, factors which had a p-value of ≤ 0.25 were included in multivariate logistic regression analysis, as suggested by Bendel & A . Odds ratios obtained using logistic regression analyses are presented as adjusted odds ratios (AOR) (Bendel and A , 1977).

Results
From a total of 341 patients, 193 (56.60%) were males and 148 (43.40%) females. The age of the subjects ranged from 18 years to 65 years with mean age of 36.98 ± 15.048 years. Among the study population, 69.6% of them were from ASA Class I, 26.4% from ASA Class II, and remaining 3.8% were from ASA Class III. More than half 54.5% of the study population were from Tajik tribe, 22.3% were Pashtoons, 19.4% were Hazaras and 3.8% were Uzbeks.
The overall prevalence of di cult intubation was 26.7%, whereas, 83 (24.3%) had slightly di cult intubation (IDS = 5), seven (2.1%) had moderate to major di cult intubation (IDS > 5), and only one patient (0.3%) detected as failed intubation (IDS > 7). Table 3 shows the socio-demographic characteristics of the subjects which had signi cant association with di cult intubation. As the table 3 shows, female participants had more risk of di cult intubation compared to male participants, with odds ratio of 1.7 and its corresponding 95% con dence interval (1.0 -2.7). Patients with more than 40 years of age had increased risk of di cult intubation, as compare to those lower than 40 years old, with odds ratio of 11.1 and its correspondent 95% con dence interval (1.0-2.7). Hazara tribe had more risk of di cult intubation as compared to other tribes, with odds ratio of 1.9 and its corresponding 95% con dence interval (1.1 -3.4). Furthermore, patients with systemic diseases (ASA II and ASA III) had increased risk for di cult intubation, as compared to those not suffering from systemic diseases with odds ratio of 4.0 and its corresponding 95% con dence interval (2.4 -6.6). In the binary logistic regression analysis, age group of patients equal or more than 40 years category in sociodemographic retained its protective effect against di cult intubation. Table 4 shows signi cant predictive factors associated with di cult intubation. As the analysis indicates, patients whose in Mallampati classes III and IV had higher risk of di cult intubation compared to those were in Mallampati classes I and II, with an odds ratio of 9.2 and its correspondent 95% con dence interval (3.7-22.7).Patients whose mouth opening was less or equal to 4 cm had higher risk of di cult intubation as compared to those with mouth opening of more than 4 cm, with an odds ratio of 10.0 and its correspondent 95% con dence interval (3.8-26.1). Patients who had thyromental distance less or equal to 6 cm getting more di cult intubation than those who had thyromental distance more than 6 cm, with an odds ratio of 4.0 and its correspondent 95% con dence interval (1.7-9.1). People who had no overbite, good extension, normal bite and easy to reverse their jaw had lower risk of di cult intubation as compared to those who had overbite and poor extension of their teeth, with odds ratio of 12.1 and its correspondent 95% con dence interval (5.2-28.0). Moreover, Patients who had limited neck mobility predisposed to di cult intubation than those who did not have any reduction in neck mobility and size, with odds ratio of 8.0 and its correspondent 95% con dence interval (3.2-20.0). The multiple logistic regression analysis of predictive factors determined that ability to prognath and mouth opening as independent predictors for di cult intubation with p-value =.004 and .036 respectively at 76.5% Hosmer and Lemshow test with adjusted odds ratio be composed of 5.38 and 5.43 respectively at 95% con dence interval. Chi-square analysis found that increasing age, systemic disease, Hazara tribe and female gender were associated with di cult in intubation in our study. This probably explains the differences in the anatomical indices that are commonly used to predict di cult intubation. Likewise, according to Smita, et al., increasing age, anthropometric differences, male sex, snoring and systemic disease (Diabetes and hypertension) have an association with di cult intubation. Maryam Motamidi et al., had also reported that with an increase of age the probability of di cult intubation rises. Furthermore, a signi cant correlation exists between upper lip biting and Mallampati score with all anthropometric factors of the body evaluated in this study, which were close to our study (Motamedi et al., 2017). In contrast, Savva et al., has not reported any signi cant difference in age, gender, systemic disease and anthropometric factors in their study (Savva, 1994).

Discussion
With regard to predictors of di cult intubations among the study population, Chi-square analysis revealed that Mallampati classes, mouth opening, thyromental distance, ability to prognath and neck mobility and size had higher risks of di cult intubation. Garg  Multiple logistic regression analysis of predictive factors determined that increasing age, ability to prognath and mouth opening were independent predictors for di cult intubation. In contrast, Garg & Dua concluded that Mallampati classes III and IV and ability to prognath were signi cant of the variables studied. Keyvan K. et al., reported that, mouth opening, chin protrusion (similar to AP in our study), and atlanto-occipital extension (similar to NM in our case) were highly signi cant for predicting di cult intubation (Karkouti et al., 2000). Smita, et al., identi ed on multivariate analysis, Mallampati classes III and IV, range of neck movement <80°, IID ≤ 3.5 cm and snoring were independently related to di cult intubation (Prakash et al., 2013).

Conclusion
Analysis of socio-demographic characteristics revealed that Hazara tribe, female patients, increasing age and systemic disease found to have signi cant associations with di cult intubation. We recognized that, Mallampati classes, mouth opening, thyromental distance, ability to prognath and neck mobility and size were associated with di cult intubation Multiple logistic regression analysis determined that increased age, ability to prognath and mouth opening were independent predictors for di cult intubation.

Recommendations
The authors would like to suggest the following recommendations: 1. In spite of various airway assessment tests no single test is 100% accurate. Therefore, it is advisable to use a combination of different tests. We would like to recommend anesthesia professionals to use the combination of routine preoperative tests to predict di cult intubation.
2. Anesthesia professionals should develop guideline for preoperative airway assessment to decrease prevalence of di cult 3. Further multicenter study should be conducted in this particular topic to develop a national guideline for preoperative airway assessments.

Limitations Of The Study
The ndings of this study are representative of the patients admitted to surgical wards of Aliabad Teaching Hospital. A larger sample size with widespread predictors would provide a broader idea of the topic.  Figure 1 Intubation Di culty Scale