Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue*

Abstract

We assessed patients after their return home following gynaecological surgery, using a daily electronic diary. Thirty-two females aged 27-77 years took part. After a hospital stay of 1-6 days (mean 2.3), they were given a pen-based electronic diary and asked to record symptoms and other data over one month. They also completed a questionnaire at the end of the study. Substantial effects on quality and duration of sleep, pain during both the night and day, interference with daily activities, energy, and ability to concentrate were recorded, mostly during the first week of treatment. Symptoms reported in the final questionnaire correlated significantly with diary data. Most patients found the electronic diary easy to use, and none found it difficult. Daily electronic diaries are an acceptable method of obtaining better information on the extent and duration of symptoms and other difficulties after discharge following surgery. The costs of healthcare provision increase the pressure for efficient use of resources. Reducing the length of hospital stay after surgery is one approach to cost reduction. To properly assess cost effectiveness, information is needed on the degree to which patients are affected by postsurgical problems on their return home, and their speed of recovery.Most of the work in this area has investigated day case surgery, which now accounts for a large proportion of surgical procedures. In Scotland, for example, about 60% of elective surgery is carried out on a day basis [1]. Some studies have investigated the immediate postoperative recovery period using functional measures (ability to drink, void urine, or walk), symptom measures (pain, nausea) or cognitive testing [2][3][4][5]. Others have used questionnaires to assess symptoms and their impact, as well as overall satisfaction, after return home. Studies considering several time-points after discharge show that a substantial proportion of patients have at least moderate pain sufficient to interfere with daily activities, after their return home [4,6,7]. As well as pain, the after effects of surgery may include cognitive impairments. Thus Tzabar et al.[8] used the Cognitive Failures Scale over a 3-day period after day case surgery, and found more failures in patients who had received a general anaesthetic compared to those given only a local anaesthetic. 1101Work on patients undergoing surgery as in-patients has mostly focused on the recovery period before discharge [9][10][11]. Myles et al.[4] administered a Quality of Recovery Scale to patients daily for 6 days then weekly for up to 6 weeks after minor or major surgery. The scale assessed wellbeing, specific functions, symptoms, and need for support. Questionnaires were administered by telephone after discharge, but it is not clear from the report how long these patients stayed in hospital. Substantially greater effects were recorded after major surgery, as expected, with scores returning to baseline after about one week. Other studies have used questionnaires to assess patient satisfa...

Airway management and oxygenation in obese patients

“…20 By using ultrasound to quantify anterior neck soft tissue at the level of the vocal cords, Erzi et al observed that morbidly obese patients in whom difficult laryngoscopy was encountered had more pre-tracheal soft tissue and a greater neck circumference than patients who experienced an uncomplicated laryngoscopy; pre-tracheal soft tissue thickness was [mean (SD)] 28 (2.7) mm vs 17.5 (1.8) mm, respectively (P \ 0.001) and neck circumference was 50 (3.8) cm vs 43.5 (2.2) cm, respectively (P \ 0.001). 21 Komatsu et al did not find increased pre-tracheal tissue to be a good predictor of difficult laryngoscopy in obese patients; 22 however, the patients in this study had a comparatively smaller neck circumference [43.5 (4.7) cm vs 44.3 (5.3) cm; P \ 0.5] in the difficult and easy laryngoscopy groups, respectively. Further studies are required to clarify the role of ultrasound and pre-tracheal adipose tissue quantification as a predictor of difficult laryngoscopy.…”

Bedside US imaging in multiple trauma patients. Part 1: US findings and techniques

“…Pretracheal fat measurement is performed at the vocal cords; it is the mean value of the distance in millimeter (mm) between the skin and the trachea measured on the central axis and 15 mm on each side. In obese patients, a pretracheal soft tissue thickness [28 mm is a more accurate predictor of difficult laryngoscopy than thyromental distance, mouth opening, modified Mallampati score, upper teeth abnormality and obstructive sleep apnea [10]. 2.…”

Role of Ultrasound in Airway Assessment and Management

“…6 The measurement of pretracheal soft tissue at the level of the vocal cords was found to be good predictor of difficult laryngoscopy in Middle Eastern obese patients in Israel. 6 However, Komatasu et al could not replicate these findings in American obese patients. 7 The difference between the two observations has been postulated due to the difference in the fat distribution between ethnic groups.…”

“…8,9 Neck ultrasound measurements are found to be as accurate as MRI for quantification of fat depth. 6 In patients with sleep apnoea, upper airway ultrasonography has been used to visualise approximation of the tongue base posteriorly and inferiorly towards the hypopharynx to cause airway obstruction. 10,11 Pharyngeal or laryngeal pathology, such as tumours, abscesses or epiglottitis which may have a significant effect during airway management, are detected by the use of US scan.…”