Does the minimal occlusive volume technique provide adequate endotracheal tube cuff pressure to prevent air leakage?: a prospective, randomized, crossover clinical study

Static respiratory compliance in anaesthetised and intubated brachycephalic dogs with and without brachycephalic obstructive airway syndrome

The impact of brachycephalic obstructive airway syndrome in dogs (BOAS) on respiratory mechanics is unclear and may affect the choice of ventilation strategies during anaesthesia. This prospective study included 56 client-owned brachycephalic dogs, allocated to be BOAS (n = 26) or non-BOAS dogs (n = 30) based on functional grading. All dogs were anaesthetised using a standardised anaesthetic protocol. Pressure-controlled ventilation was initiated around 30minutes post-induction, maintaining peak inspiratory pressure at 7-12cm H2O. Static respiratory compliance (Cstat) was recorded at predetermined time points in sternal, right and left lateral recumbency. Thorax dimensions were assessed with a tape measure. Body surface area (BSA) was calculated and the ratio Cstat/BSA used as the main outcome variable. Comparison of means/medians, analysis of proportions, the Spearman correlation coefficient and both logistic and linear regression were used for data analysis. P < 0.05 was considered statistically significant. Non-BOAS dogs showed significantly higher Cstat/BSA compared to BOAS dogs in sternal (41.6 (31.1-51.8) vs. 32.9 (24.4 - 39.2), respectively, P = 0.028), right lateral (36.2 (25.7 - 46.4) vs. 27.0 (22.7 - 35.6); P = 0.026) and left lateral (33.6 (22.6 - 45.5) vs. 24.6 (18.4 - 32.2); P = 0.020) recumbencies. For all dogs, the Cstat/BSA ratio was higher in sternal compared to lateral recumbencies. BOAS dogs had a significantly shorter distance between thoracic inlet and last rib compared to non-BOAS dogs (20 ± 4 vs. 23 ± 6cm, respectively; P = 0.043). Reduced respiratory compliance in BOAS-affected dogs should be considered during mechanical ventilation.

Relationship between difference in endotracheal tube cuff area and airway area with minimum cuff pressure for adequate airway sealing: a prospective observational study

It is essential for clinicians to select the appropriate endotracheal tube to ensure effective airway management. However, an unmatched endotracheal tube cuff area to the airway area can lead to air or secretion leakage, even at the recommended cuff pressure of 20-30 cmH2O. The present multicenter prospective observational study aimed to determine the relationship between the difference in cuff area and airway area with the minimum cuff pressure to avoid airway leakage. Adult patients who underwent mechanical ventilation were assigned into three groups, with a minimum cuff pressure of < 20, 20-30, and > 30 cmH2O, respectively, in order to have adequate airway sealing. The primary outcome was the difference between the endotracheal tube cuff area and airway area (cuff-airway area difference) that was calculated for the three groups. A total of 284 patients were included, with the mean age of 65.19 (± 14.03) years old. There were 166, 63 and 55 patients who required a minimum cuff pressure of < 20, 20-30 and > 30 cmH2O, respectively. The mean cuff-airway area difference was 236.00 ± 85.26, 149.70 ± 48.34 and - 12.29 ± 113.0 mm2 in the < 20, 20-30, and > 30 cmH2O groups, respectively. In addition, the simple linear regression analysis revealed a negative linear relationship between the cuff-airway area difference and minimum cuff pressure (Y = -0.1266 × X + 46.50, F = 571.40, p < 0.001). It can be concluded that a significant number of patients require a cuff pressure out of the recommended range (< 20 or > 30 mmH2O) to have adequate airway sealing. Patients with a lower cuff-airway area difference require a higher minimum cuff pressure to seal the airway.

Risk factor evaluation of cuff pressure of >30 cmH2O to stop air leakage during mechanical ventilation: A prospective observational study

AIM

The commonly recommended endotracheal tube cuff pressure is 20-30 cmH2O. However, some patients require a cuff pressure of >30 cmH2O to prevent air leakage. The study aims to determine the risk factors that contribute to the endotracheal tube cuff pressure of >30 cmH2O to prevent air leakage.

DESIGN

A multi-centre prospective observational study.

METHODS

Eligible patients undergoing mechanical ventilation in the intensive care unit of three hospitals between March 2020 and July 2022 were included. The endotracheal tube cuff pressure to prevent air leakage was determined using the minimal occlusive volume technique. The patient demographics and clinical information were collected.

RESULTS

A total of 284 patients were included. Among these patients, 55 (19.37%) patients required a cuff pressure of >30 cmH2O to prevent air leakage. The multivariate logistic regression results revealed that the surgical operation (odds ratio [OR]: 8.485, 95% confidence interval [CI]: 1.066-67.525, p = 0.043) was inversely associated with the endotracheal tube cuff pressure of >30 cmH2O, while the oral intubation route (OR: 0.127, 95% CI: 0.022-0.750, p = 0.023) and cuff inner diameter minus tracheal area (OR: 0.949, 95% CI: 0.933-0.966, p < 0.001) were negatively associated with the endotracheal tube cuff pressure of >30 cmH2O. Therefore, a significant number of patients require an endotracheal tube cuff pressure of ＞30 cmH2O to prevent air leakage. Several factors, including the surgical operation, intubation route, and difference between the cuff inner diameter and tracheal area at the T3 vertebra, should be considered when determining the appropriate cuff pressure during mechanical ventilation.

Effect of Minimum Bronchial Cuff Volume of Left-Sided Double-Lumen Tube for One-Lung Ventilation on the Change in Bronchial Cuff Pressure during Lateral Positioning in Thoracic Surgery: A Prospective Observational Study

The minimum bronchial cuff volume (BCVmin) of a double-lumen tube (DLT) without air leaks during lung isolation may vary among individuals, and lateral positioning could increase the bronchial cuff pressure (BCP). We investigated the effect of initially established BCVmin (BCVi) on the change in BCP by lateral positioning. Seventy patients who underwent elective lung surgery were recruited and divided into two groups according to the BCVi obtained during anesthetic induction in each patient. Outcome analysis was conducted using data from 39 patients with a BCVi greater than 0 (BCVi > 0 group) and 27 with a BCVi of 0 (BCVi = 0 group). The primary outcome was a change in the value measured in the supine and lateral positions of the initially established BCP (BCPi; BCP at the time of BCVi injection), which was significantly larger in the BCVi > 0 group than in the BCVi = 0 group (1.5 (0.5-6.0) cmH₂O vs. 0.0 (0.0-1.0) cmH₂O; p < 0.001). BCVi was related to the left main bronchus (LMB) diameter (Spearman's rho = 0.676, p < 0.001) and the gap between the LMB diameter and the outer diameter of the bronchial cuff (Spearman's rho = 0.553, p < 0.001). Therefore, selecting a DLT size with a bronchial cuff that fits each patient's LMB may be useful in minimizing the change in BCP when performing lateral positioning during thoracic surgery. If the bronchial cuff requires unavoidable initial inflation, it is necessary to be aware that BCP may increase during lateral positioning and to monitor the BCP regularly if possible.