The Shape of the Human Adult Trachea

Mackenzie, Colin F.; McAslan, T. Crawford; Shin, Beomsu; Schellinger, Dieter; Helrich, Martin

doi:10.1097/00000542-197807000-00015

Cited by 42 publications

(13 citation statements)

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“…We think that anatomical differences between patients may be responsible for this observation. Autopsy studies 14,21 indicated that tracheal cartilage rings can differ substantially from the classic horseshoe shape.…”

Section: Discussionmentioning

confidence: 99%

Cuff Pressure of Endotracheal Tubes After Changes in Body Position in Critically Ill Patients Treated With Mechanical Ventilation

Lizy¹,

Swinnen²,

Labeau³

et al. 2014

American Journal of Critical Care

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Background In order to avoid microaspiration and tracheal injury, the target for endotracheal tube cuff pressure is 20 to 30 cm H 2 O. Objective To assess the effect of changes in body position on cuff pressure in adult patients. Methods Twelve orally intubated and sedated patients received neuromuscular blockers and were positioned in a neutral starting position (backrest, head-of-bed elevation 30º, head in neutral position) with cuff pressure at 25 cm H 2 O. Then, 16 changes in position were performed: anteflexion head, hyper extension head, left and right lateral flexion of head, left and right rotation of the head, semirecumbent position (head-of-bed elevation 45°), recumbent position (head-of-bed elevation 10°), horizontal backrest, Trendelenburg position (10°), and left and right lateral positioning over 30°, 45°, and 90°. Once a patient was correctly positioned, cuff pressure was recorded during an end-expiratory ventilatory hold. The pressure observed was compared with the cuff pressure at the starting position. Values outside the target range (20-30 cm H 2 O) were considered clinically relevant. Results A total of 192 measurements were performed (12 subjects x 16 positions). A significant deviation in cuff pressure occurred with all 16 changes (P < .05). No pressures were less than the lower limit (20 cm H 2 O). Pressures were greater than the upper limit (30 cm H 2 O) in 40.6% of the measurements. In each position, the upper target limit was exceeded at least once. Within-patient variability was substantial (P = .02). Conclusion Simple changes in patients' positioning can result in potentially harmful cuff pressures.

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Section: Discussionmentioning

confidence: 99%

Cuff Pressure of Endotracheal Tubes After Changes in Body Position in Critically Ill Patients Treated With Mechanical Ventilation

Lizy¹,

Swinnen²,

Labeau³

et al. 2014

American Journal of Critical Care

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“…A syringe barrel or glass tube avoids the problems of rapid deterioration of freshly excised tracheas and poor correlation between species. The cross‐sectional shape and circumference of the human trachea have been investigated previously [10, 11]. Six cross‐sectional shapes have been identified: elliptical, triangular, circular, C‐shaped, U‐shaped and D‐shaped.…”

Section: Discussionmentioning

confidence: 99%

Pressure in the cuffs of tracheal tubes at altitude

Smith

McArdle

2002

Anaesthesia

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SummaryPressures in the cuffs of three commonly used tracheal tubes (Portex Pro®le SoftsealÒ, Mallinckrodt Lo-ContourÒ and Mallinckrodt Hi-ContourÒ, size 8.0 mm and 9.0 mm internal diameter), in¯ated with air, were measured during simulated ascents in an altitude chamber to 10 000 ft. There was no detectable difference in performance between sizes for each type of tracheal tube. When averaged over the two sizes for each type of tube, cuff pressure reached the critical perfusion pressure 50 cmH 2 O (37 mmHg) for tracheal mucosa at a higher altitude in the Portex Pro®le Softseal (2837 ft, 95% CI 2488±3186 ft) than in the Mallinckrodt Lo-Contour (2128 ft, 95% CI 1779±2476 ft; p 0.02) and Mallinckrodt Hi-Contour (1820 ft; 95% CI 1471±2168 ft; p 0.002) tracheal tubes. When the cuffs of the 9.0-mm tracheal tubes were in¯ated with saline, much smaller increases in pressure were measured with increasing altitude, although in¯ation of the cuffs with saline was technically dif®cult. Commonly used tracheal tubes with air-in¯ated cuffs can be used for aeromedical retrieval, but air should be evacuated from the cuffs after increases in altitude of as little as 2000±3000 ft.

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“…Variations in ICP due to environmental factors, interventions and patient-related factors have already been shown in the literature. Environmental factors such as high altitude 15 (transport by helicopter), interventions such as positive-pressure ventilation 16 or ventilation with nitrous oxide 17 and any anatomical variations 18 , 19 or pathological processes including constriction of the airway cause an increase in ICP. On the other hand, use of muscle relaxing agents might cause a decrease in ICP.…”

Section: Discussionmentioning

confidence: 99%