PATHOPHYSIOLOGY, EVALUATION, AND TREATMENT OF THE DIFFICULT AIRWAY

Predisposing Factors of Difficult Tracheal Intubation Among Adult Patients in Aliabad Teaching Hospital in Kabul, Afghanistan – A Prospective Observational Study

Background

Airway management may be a considerable challenge for anesthesiologists. Currently used preoperative screening tests are known to lack sufficient specificity and sensitivity. Nevertheless, preoperative screenings and the combination of various tests are highly recommended to reduce the risk of unexpected difficult or failed airway management.

Purpose

This study aims to determine if socio-demographic characteristics can predict difficult intubation among adult patients scheduled for elective surgeries under general anesthesia in Aliabad Teaching Hospital, Kabul, Afghanistan.

Methods

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 ethnicity were recorded for each participant. Airway assessment tests such as mouth opening (MO), thyromental distance (TMD), and Mallampati classes, inability to prognath (AP) and neck mobility and size (NM) category were conducted by research team. Data were initially entered into an Excel data sheet and then exported to SPSS Statistics version 22 for analysis.

Results

From 28 October 2018 to 30 January 2019, a total of 341 patients included in the study. Of these, 193 (56.6%) were male and 148 (43.4%) were female. The mean age of the subjects was 36.98 ± 15.048 years. More than half (54.5%) of the study population were Tajiks. Patients from the Hazara ethnicity, female patients, older patients and those suffering from systemic diseases found to be more difficult to intubate. We recognized that, Mallampati classes ≥3, small MO, short TMD, AP, reduced NM were also associated with difficult intubation. Multiple logistic regression analysis of the associated factors determined that increased age more than 40 years, AP and small MO were independent predictors of difficult intubation.

Conclusion

The study findings show that Hazara ethnicity, female patients, increasing age and systemic disease have significant associations with difficult intubation. Mallampati classes III and IV, MO ≤4 cm, TMD ≤6 cm, and reduced NM had higher risks of difficult intubation. Multiple logistic regression analysis determined that increased age, AP and MO were independent predictors for difficult intubation.

Ultrasound as an Assessment Method in Predicting Difficult Intubation: A Prospective Clinical Study

Objective

Aim of the study is to predict the difficulty in intubation preoperatively using ultrasonography.

Methods

One hundred and thirty-seven patients underwent ultrasound followed by surgery under general anesthesia. A experienced radiologist examined the airway and performed measurements of specific airway parameters: visualization of hyoid bone, visualization of vocal cords through thyroid cartilage, visualization of epiglottis, distance from base of tongue to hyoid bone, distance of hyomental region distance of thyrohyoid region, distance between skin and fat pad thickness to thyroid cartilage, thickness of submental region, distance from epiglottis to skin (above hyoid), and visualization of cricothyroid membrane. After performing ultrasound, patient was presented for surgery. An experienced anesthesiologist who is associated with this study did all the laryngoscopy and intubation.

Results

We were able to visualize all relevant anatomical structures in all the participants using ultrasound. The receiver operating characteristic curve analysis results showed that hyomental is ≤ 1.09 (P value < 0.01) to classify difficult in intubation.

Conclusion

The study shows that ultrasound can reliably image all the airway structures. This study suggests that hyomental distance is a more valid criterion in predicting difficult intubation. Further, case control study is needed for assessing the ease of intubation.

Delayed recognition of esophageal intubation

It is important for clinicians to be aware of the sensitivity and limitations of commonly used methods to confirm endotracheal tube placement. Overreliance on insensitive indicators can lead to delayed recognition of esophageal intubation. The case presented highlights this concern.

Target-controlled infusion of remifentanil for laryngeal mask airway insertion during sevoflurane induction in adults

OBJECTIVE

This randomized, double-blind study investigated the suitable target effect-site concentration of remifentanil for laryngeal mask airway (LMA) insertion during inhalation induction with sevoflurane.

METHODS

Patients aged 18 - 60 years were randomly assigned to one of three groups receiving infusions of normal saline (control group), or infusions with target effect-site remifentanil concentrations of either 1 ng/ml (R1 group) or 2 ng/ml (R2 group), 1 min after the induction of anaesthesia with sevoflurane. LMA insertion was attempted 2 min after induction. Insertion conditions were graded using a six-variable, three-point scale (excellent, intermediate or poor).

RESULTS

A total of 102 patients were included. The proportion of patients ranked as excellent for the LMA insertion was significantly higher in groups R1 and R2 compared with the control group. The incidence of apnoea was significantly more frequent in the R2 group than in the control or R1 groups.

CONCLUSIONS

Compared with 1 ng/ml remifentanil or normal saline, target-controlled infusion of 2 ng/ml remifentanil significantly improved the LMA insertion conditions during sevoflurane inhalational induction, although apnoeic episodes were more frequently observed.

[Evaluation of a protocol for predicting difficult airway in routine practice: interobserver agreement]

OBJECTIVES

To evaluate a protocol for routine assessment of potential risk factors for difficult airway intubation in an anesthesia department, by measuring interobserver agreement and the behavior of the factors in a predictive model.

MATERIAL AND METHODS

A cross-sectional study group of 320 consecutive patients undergoing major surgery requiring orotracheal intubation was assessed for possible difficult airway. We calculated interrater agreement for recording of the Mallampati score, thyromental distance less than 6 cm, thick neck, kyphosis, small mouth, macroglossia, and dental prosthesis during the preanesthesia examination (by an anesthetist) and on the day of the operation (by an anesthetist and a resident). We constructed a model to predict difficult intubation (requiring 3 or more attempts).

RESULTS

The kappa indices of agreement between the anesthetists at the preoperative examination and in the operating room or the resident were all less than 0.6. Factors like thyromental distance, small mouth, and kyphosis had kappa indices less than 0.21. The kappa index between the resident and the anesthetist in the operating room was over 0.55. The only factor that had a different level of agreement was the presence or not of a dental prosthesis. None of the studied individual factors, nor these factors in association with the Mallampati score, achieved significance in a bivariate regression model to predict difficult intubation.

CONCLUSIONS

There is poor interobserver agreement on factors for predicting difficult airway in comparisons between preoperative and operating room assessment by an anesthetist or a resident. The individual predictive factors and their association with the Mallampati score did not prove useful for predicting difficult intubation.

A case of tracheal injury with intubation during electroconvulsive therapy

Respiratory complications related to electroconvulsive therapy (ECT) are a rare occurrence. The need for endotracheal intubation during ECT is rarely indicated. We report a case of a 47-year-old woman with severe gastroesophageal reflux disease and depression who was intubated for her first 3 ECT treatments. She developed a small tracheal tear after her third ECT treatment which resulted in subcutaneous emphysema, pneumopericardium, and pneumomediastinum. The tracheal tear resolved spontaneously and ultimately the patient underwent subsequent ECT treatments successfully without intubation. This case is the first reported case of complications related to endotracheal intubation during ECT.

Critical care of the head and neck patient

The patient with head and neck disease has several peculiarities that need to be recognized for the treating team to offer optimal care. These arise from the primary disorders (eg, head and neck cancer or injuries) and the morbidity they might cause, the associated comorbidities, and the possible complications of treatment. A team approach involving the surgeon, the intensivist, and other caretaking personnel is essential to achieve high-quality care and ensure the best results possible.

Should we reevaluate the variables for predicting the difficult airway in anesthesiology?

Anesthesiologists have often been confronted with the difficult question of determining which patient will present an increased difficulty for endotracheal intubation. The limits of the previously reported morphometric airway measurements for predicting difficult intubation have inadequately addressed the normal patient population variables. We designed this prospective study to investigate the age and sex-related changes in the morphometric measurements of the airway in a large group of patients without anatomic abnormality and a group of cadavers. Hyomental, thyromental, sternomental distances, neck extension, and Mallampati scores were evaluated in 12 cadavers and in 334 patients. Patients were allocated to three groups based on age: Group 1 (20-30 yr), Group 2 (31-49 yr), and Group 3 (50-70 yr). Male and female sex differences were also evaluated. Hyomental distance was the only variable not affected by age. In addition, the mean population values were less than the threshold values suggested as criteria for difficult endotracheal intubation. All the other criteria were age-dependent and inversely affected by the increase in age. Male sex was also a distinction for increased measurements of all the morphometric distances. The mean degree of neck extension was similar in both sex groups. This study provides a more comprehensible approach to the morphometric measurements of the human airway. Adequate data of normal values may help the clinician to identify patients that are outside the range and therefore may be challenging.

IMPLICATIONS

This study was performed to establish data on the average values of airway morphology in the adult population of different age groups and sex. Hyomental, thyromental, sternomental distances and neck extension values were measured on 12 cadavers and 334 patients.

Rapid sequence intubation of the pediatric patient. Fundamentals of practice

Rapid-sequence intubation and rapid sequence induction of general anesthesia are synonyms and refer to the technique of choice for tracheal intubation in many pediatric patients in the emergency department. The principles of safe practice and basic standards of care uniformly apply to all clinical situations in which the technique is performed. RSI has two basic technical components: induction of general anesthesia and direct laryngoscopy with tracheal intubation. The technique is a prescribed protocol that can be modified slightly by the clinical circumstances. RSI is designed to rapidly create ideal intubating conditions, attenuate pathophysiologic reflex responses to direct laryngoscopy and tracheal intubation, and reduce the risk for pulmonary aspiration. Optimal performance requires appropriate training and knowledge, technical skill, and sound medical judgment. Medical and airway evaluation, careful patient selection, recognition of the need for consultation or safer alternatives, thorough familiarity with appropriate drug management, and attention to detail are essential for minimizing the risk for adverse complications. RSI with a rapid injection of preselected dosages of an anesthetic induction agent and muscle relaxant is the pharmacologic technique of choice. Premedication should not be routinely used. Anticipation, recognition, and management of complications are inherent to the competent delivery of all medical care. The unanticipated difficult airway is arguably the most severe complication of RSI, and all individuals performing the technique must prepare in advance a specific plan for this scenario. As with all such skills or procedures, a quality assurance program is important to monitor care, and individuals practicing RSI need to take appropriate steps to maintain competence.

Preoperative evaluation of the pulmonary patient undergoing nonpulmonary surgery

As the human population continues to live longer, patients with chronic pulmonary disease are increasingly presenting for surgical treatment. The influences of general anesthesia and an operative procedure are well known to negatively impact pulmonary gas exchange. Pulmonary-compromised patients are at high risk for the development of perioperative complications as a consequence of not only their pulmonary disease but of associated comorbid disease processes. Certain risk factors associated with preexisting pulmonary conditions are known to increase the likelihood of intraoperative or postoperative complications. Essential components in the comprehensive care of these patients are the identification of these high-risk patients and the implementation of an inclusive perianesthetic care regimen designed to decrease pulmonary complications. This article will familiarize the perianesthetic nurse with pertinent skills required to effectively assess and prepare patients with pulmonary disease for their upcoming surgery.