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The accuracy of locating the cricothyroid membrane by palpation - an intergender study.

Campbell M, Shanahan H, Ash S, Royds J, Husarova V, McCaul C - BMC Anesthesiol (2014)

Bottom Line: Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02).CTM localisation is more difficult in female subjects irrespective of body habitus.It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.

ABSTRACT

Background: The cricothyroid membrane (CTM) is the recommended site of access to the airway during cricothyrotomy to provide emergency oxygenation. We sought to compare the ability of physicians to correctly identify the CTM in male and female patients.

Methods: In a prospective observational study, anaesthetists were asked to locate the CTM by palpation which was then identified using ultrasound and the distance between the actual and estimated margin of the CTM was measured. Participants assessed the ease of CTM palpation using a visual analog scale. In a second series, the angulation of the posterior junction of the thyroid laminae was measured using ultrasound.

Results: 23 anaesthetists and 44 subjects participated. A total of 36 assessments were carried out in each gender. Incorrect identification of the CTM was more common in females (29/36 vs. 11/36, P < 0.001) and the distance from the CTM in the vertical plane was greater (11.0 [6.5-20.0] vs. 0.0 [0.0-10.0] mm, P < 0.001). In females distance from the CTM correlated positively with neck circumference (P = 0.005) and BMI (P = 0.00005) and negatively with subject height (P = 0.01). Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02). VRS palpation correlated with decreased posterior thyroid cartilage angulation (P = 0.04).

Conclusions: CTM localisation is more difficult in female subjects irrespective of body habitus. It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.

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Fig1: Flow diagram.

Mentions: Using a convenience sample, 44 subjects agreed to take part in the study and consisted of 24 females and 20 Males. (Figure 1, Table 1) Both patients and members of staff acted as subjects. The 23 participants were anaesthetists who were asked to identify the CTM of the subjects. A total of 36 assessments were performed on each gender. Some of the subjects were examined more than once depending on the availability of participating anaesthetists. The median number of assessments performed per participant was 1 (IQR 1.0 – 3.0) and assessments per subject was 1 (IQR 1.0 – 2.0). 18 of the 23 anaesthetists had 3 or more years of speciality training. The methodology used has been described in detail elsewhere [9]. Briefly, the subject lay in the supine position and the CTM was identified by the assessors (MC, CMC) by palpation with ultrasonic confirmation. The limits of the CTM and the midline were marked with ink visible only on exposure to ultraviolet illumination. The participants were asked to identify the CTM by palpation with the subject’s head in the supine neutral position. The participant was asked to mark the skin overlying the CTM using the UV ink pen. The assessor then measured the distance between CTM and the estimates of the participant in both the vertical and lateral axes. A ‘correct’ estimation was defined as a mark made between the upper and lower limits of the membrane and within 5 mm of midline [9].Figure 1


The accuracy of locating the cricothyroid membrane by palpation - an intergender study.

Campbell M, Shanahan H, Ash S, Royds J, Husarova V, McCaul C - BMC Anesthesiol (2014)

Flow diagram.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4384292&req=5

Fig1: Flow diagram.
Mentions: Using a convenience sample, 44 subjects agreed to take part in the study and consisted of 24 females and 20 Males. (Figure 1, Table 1) Both patients and members of staff acted as subjects. The 23 participants were anaesthetists who were asked to identify the CTM of the subjects. A total of 36 assessments were performed on each gender. Some of the subjects were examined more than once depending on the availability of participating anaesthetists. The median number of assessments performed per participant was 1 (IQR 1.0 – 3.0) and assessments per subject was 1 (IQR 1.0 – 2.0). 18 of the 23 anaesthetists had 3 or more years of speciality training. The methodology used has been described in detail elsewhere [9]. Briefly, the subject lay in the supine position and the CTM was identified by the assessors (MC, CMC) by palpation with ultrasonic confirmation. The limits of the CTM and the midline were marked with ink visible only on exposure to ultraviolet illumination. The participants were asked to identify the CTM by palpation with the subject’s head in the supine neutral position. The participant was asked to mark the skin overlying the CTM using the UV ink pen. The assessor then measured the distance between CTM and the estimates of the participant in both the vertical and lateral axes. A ‘correct’ estimation was defined as a mark made between the upper and lower limits of the membrane and within 5 mm of midline [9].Figure 1

Bottom Line: Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02).CTM localisation is more difficult in female subjects irrespective of body habitus.It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.

ABSTRACT

Background: The cricothyroid membrane (CTM) is the recommended site of access to the airway during cricothyrotomy to provide emergency oxygenation. We sought to compare the ability of physicians to correctly identify the CTM in male and female patients.

Methods: In a prospective observational study, anaesthetists were asked to locate the CTM by palpation which was then identified using ultrasound and the distance between the actual and estimated margin of the CTM was measured. Participants assessed the ease of CTM palpation using a visual analog scale. In a second series, the angulation of the posterior junction of the thyroid laminae was measured using ultrasound.

Results: 23 anaesthetists and 44 subjects participated. A total of 36 assessments were carried out in each gender. Incorrect identification of the CTM was more common in females (29/36 vs. 11/36, P < 0.001) and the distance from the CTM in the vertical plane was greater (11.0 [6.5-20.0] vs. 0.0 [0.0-10.0] mm, P < 0.001). In females distance from the CTM correlated positively with neck circumference (P = 0.005) and BMI (P = 0.00005) and negatively with subject height (P = 0.01). Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02). VRS palpation correlated with decreased posterior thyroid cartilage angulation (P = 0.04).

Conclusions: CTM localisation is more difficult in female subjects irrespective of body habitus. It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.

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