Abstract
Background
Endotracheal tube cuff pressure may fluctuate during routine intensive care unit (ICU) care despite standard monitoring. We evaluated short-term cuff pressure changes after repositioning according to measurement time, patient position, sedation level, and body mass index.
Material/Methods
This prospective observational study included 103 mechanically ventilated adult ICU patients. Before repositioning, cuff pressure was adjusted to 20 to 30 cm H2O when necessary, and the resulting value was recorded as T0. Patients were placed in the head-elevated supine, right lateral, or left lateral position. Cuff pressure was remeasured at 1 (T1) and 5 (T2) minutes after repositioning. Repeated measurements obtained during routine positioning cycles over a 2-day period were analyzed via mixed-effects models.
Results
In total, 4944 cuff pressure measurements were analyzed. Cuff pressure significantly increased over time, from 27.67 ± 2.27 cm H2O at T0 to 28.11 ± 2.89 cm H2O at T1 and 28.29 ± 3.23 cm H2O at T2 (P < 0.001); the absolute magnitude of change was small. No significant differences were detected among target positions (P > 0.05). Higher Richmond Agitation-Sedation Scale (RASS) scores were independently associated with increased cuff pressure (β = 0.94 cm H2O per 1-point increase; P < 0.001) and higher odds of out-of-range cuff pressure (odds ratio, 7.21; P < 0.001).
Conclusions
Endotracheal tube cuff pressure showed statistically significant short-term changes after repositioning. Higher RASS scores were associated with greater cuff pressure variability and higher odds of out-of-range cuff pressure. Repeated cuff pressure reassessment after repositioning may be beneficial, particularly in patients with higher RASS scores or greater agitation.
Keywords: Deep Sedation; Intensive Care Units; Intubation, Intratracheal; Ventilation
Introduction
Endotracheal tube cuff pressure management is an essential component of airway care in mechanically ventilated intensive care unit (ICU) patients. Maintaining cuff pressure within the recommended therapeutic range is necessary to ensure an adequate airway seal, effective ventilation, and prevention of microaspiration [1,2]. However, cuff pressure is not static and may fluctuate during routine ICU care, potentially leading to clinically important complications associated with both insufficient and excessive cuff pressure [2,3].
Low cuff pressure may permit air leakage and microaspiration of contaminated subglottic secretions, thereby increasing the risk of ventilator-associated pneumonia (VAP) [4,5]. In contrast, excessive cuff pressure may impair tracheal mucosal perfusion and contribute to ischemia, ulceration, tracheal injury, and other post-intubation complications [2,3,6]. Therefore, regular monitoring and maintenance of cuff pressure within the recommended therapeutic range are considered essential components of airway care in mechanically ventilated patients. Current international guidelines and previous clinical studies recommend maintaining cuff pressure within a target range of 20 to 30 cm H2O [1,7–9].
In clinical practice, cuff pressure may fluctuate over time despite routine monitoring. Previous studies have shown that cuff pressure can be influenced by several clinical and care-related factors, including changes in airway pressure, ventilator-related variables, endotracheal tube position, and patient-related factors such as movement and sedation level [6,8,9]. Moreover, out-of-range cuff pressure remains common among mechanically ventilated patients, emphasizing the need for structured and repeated monitoring strategies in ICU practice [9,10].
Continuous cuff pressure control has been investigated as a preventive strategy to reduce the incidence of VAP [11,12]. Although continuous monitoring may improve pressure stability, cuff pressure can still be influenced by routine clinical care and patient-related factors. Among these, patient repositioning is a particularly relevant intervention in ICU care. Position changes are frequently performed to improve oxygenation, prevent pressure injuries, facilitate secretion drainage, and optimize overall patient care. Nevertheless, repositioning may alter the relationship between the endotracheal tube cuff and the tracheal wall, leading to clinically significant changes in cuff pressure [13–15].
In addition to body position, the timing of cuff pressure measurement may be clinically important. Previous studies have demonstrated that patient repositioning can influence endotracheal tube cuff pressure in mechanically ventilated patients [13–16]. However, most available studies have evaluated cuff pressure changes after isolated position changes or at single measurement intervals; limited data are available regarding short-term temporal changes during repeated routine positioning cycles in ICU practice. Furthermore, the combined effects of measurement time, target position, and patient-related factors such as sedation level have not been comprehensively evaluated within the same analytical model.
Therefore, the primary objective of this prospective observational study was to evaluate short-term changes in endotracheal tube cuff pressure after routine patient repositioning in mechanically ventilated ICU patients. We specifically focused on repeated measurements obtained during routine ICU positioning cycles over a 2-day observation period. We hypothesized that cuff pressure would substantially change after repositioning, even over short observation periods despite initial adjustment within the recommended therapeutic range.
Secondary objectives were to investigate whether target position, sedation level assessed using the Richmond Agitation-Sedation Scale (RASS), and body mass index (BMI) were independently associated with cuff pressure variability and predefined cuff-related clinical events.
Material and Methods
Ethics Approval and Consent to Participate
The study was conducted in accordance with the Declaration of Helsinki and was approved by the Clinical Research Ethics Committee of Bursa Yuksek Ihtisas Training and Research Hospital (approval date: August 27, 2025; protocol number: 2024-TBEK 2025/08-04). Written informed consent was obtained from all patients or their legal representatives.
Animal and Human Rights Statement
All procedures performed in this study were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Study Design and Setting
This prospective observational study was conducted in the adult ICU of Bursa Yuksek Ihtisas Training and Research Hospital between September 15, 2025, and March 15, 2026. The study was designed to evaluate short-term positional and temporal changes in endotracheal tube cuff pressure in mechanically ventilated ICU patients.
All procedures were performed as part of routine clinical care, and no additional interventions were introduced specifically for study purposes.
Study Population
Adult patients who were endotracheally intubated and receiving invasive mechanical ventilation in the ICU during the study period were screened for eligibility. Patients aged 18 years or older who were expected to remain in the ICU for at least 2 days were eligible for inclusion.
Patients were excluded if they were unable to tolerate position changes, were extubated before completion of the measurement period, or could not be positioned according to the study protocol. Patients with incomplete cuff pressure measurements were also excluded from the final analysis.
Given the observational study design, no control group was included, and no randomization was performed. All measurements were obtained during routine ICU care, and the sequence of patient positioning was determined in accordance with standard clinical practice.
The patient selection process is summarized in Figure 1.
Figure 1.
Flowchart of patient selection, exclusions, and cuff pressure measurement protocol during the 2-day observation period. ICU, intensive care unit.
Cuff Pressure Measurement Protocol
All patients were intubated with standard high-volume, low-pressure cuffed endotracheal tubes made of polyvinyl chloride. Endotracheal tube cuff pressure was measured using a manual cuff pressure manometer (VBM Medizintechnik GmbH, Sulz am Neckar, Germany).
The manual cuff pressure manometer was calibrated before measurements were initiated for each newly enrolled patient. Calibration was performed at the beginning of each patient’s measurement period, rather than before each repeated measurement. The same device and standardized measurement technique were used throughout the study. No independent laboratory validation of device accuracy was performed specifically for the study.
All measurements were performed by trained ICU staff who were familiar with the study protocol.
During each 24-hour shift, cuff pressure measurements were performed by the ICU nurse assigned to the patient. Patient repositioning was performed by the assigned nurse with 2 additional staff members, in accordance with the routine ICU positioning protocol. Patients remained connected to the mechanical ventilator throughout cuff pressure measurement; no study-specific changes were made to ventilator settings or sedation. Measurements were not synchronized to a predefined phase of the respiratory cycle. If coughing or active patient movement occurred during a manometer reading, the measurement was discarded and repeated after the patient had returned to a clinically stable state. The same measurement conditions were applied at T0, T1, and T2.
In routine ICU care, patients were repositioned every 3 hours among 3 target positions: right lateral, left lateral, and head-elevated supine. The head-elevated supine position was defined as the patient lying on their back with the head of the bed elevated at least 30°. The preparatory supine position was defined as the initial flat supine position before each repositioning maneuver.
For each positioning cycle, cuff pressure was first measured while the patient was in the preparatory supine position; it was adjusted to the recommended target range of 20 to 30 cm H2O when necessary. The cuff pressure recorded after this adjustment was defined as T0. The patient was then repositioned to the assigned target position; cuff pressure was measured at 1 (T1) and 5 (T2) minutes after positioning.
For right or left lateral positioning, the patient was turned to the corresponding side, supported with pillows, and the head of the bed was elevated at least 30°. For the head-elevated supine position, the patient was placed on their back with the head of the bed elevated at least 30°. After the target position was achieved, cuff pressure was measured at 1 minute and 5 minutes; these values were recorded as T1 and T2, respectively.
Cuff pressure was assessed at 3 predefined time points during each positioning cycle: T0 (before repositioning), T1 (1 minute after positioning), and T2 (5 minutes after positioning).
The same measurement protocol was applied for all target positions. Measurements were repeated over a 2-day observation period for each patient. The sequence of positioning was not randomized and followed routine ICU practice.
Data Collection and Investigated Parameters
Demographic and clinical data were prospectively recorded for all patients using a standardized data collection form. Recorded variables included age, sex, BMI, ventilator parameters, sedation level, endotracheal tube insertion depth at the incisors, and endotracheal tube displacement during position changes.
Ventilator parameters, including positive end-expiratory pressure, pressure support, and tidal volume, were recorded from the mechanical ventilator at the time of each cuff pressure measurement.
Sedation level was assessed at each measurement time point using the RASS, a 10-point bedside scale ranging from −5 (unarousable) to +4 (combative), with 0 indicating an alert and calm state. Higher RASS scores indicated lighter sedation or greater agitation, whereas lower scores indicated deeper sedation [17]. Sedation was managed in accordance with routine ICU practice and titrated based on each patient’s clinical condition. No study-specific sedation target was defined.
Endotracheal tube insertion depth was recorded at the level of the incisors at each measurement time point. Tube displacement was defined as a change of at least 1 cm in insertion depth compared with the previous measurement.
At each cuff pressure measurement time point, the following predefined clinical events were recorded:
Out-of-range cuff pressure: cuff pressure below 20 cm H2O or above 30 cm H2O
Air leak alarm: occurrence of a ventilator air leak alarm during the measurement period
Endotracheal tube displacement of at least 1 cm: as defined above
All data were collected during routine ICU care; no modifications were made to ventilator settings, sedation management, or patient positioning for study purposes.
Outcomes
The primary outcome was the change in endotracheal tube cuff pressure across the predefined measurement time points: baseline before repositioning (T0), 1 minute after the target position was achieved (T1), and 5 minutes after the target position was achieved (T2).
Secondary outcomes were the associations of target position, RASS score, and BMI with cuff pressure. Additional secondary outcomes included predefined clinical events: out-of-range cuff pressure (< 20 cm H2O or > 30 cm H2O), air leak alarm, and endotracheal tube displacement of at least 1 cm. Clinical events were assessed on a positioning-cycle basis and a patient basis.
Statistical Analysis
Continuous variables were expressed as mean ± standard deviation, whereas categorical variables were presented as counts and percentages. The distributions of continuous variables were evaluated by visual inspection and assessment of their distributional characteristics.
An a priori sample size calculation was performed using G*Power software [18] for repeated-measures analysis of variance within factors. Based on a conservative small-to-moderate effect size (Cohen’s f = 0.19), an α error probability of 0.05, 90% statistical power, 3 repeated measurements, an assumed correlation of 0.50 among repeated measures, and a nonsphericity correction of 0.75, the minimum required sample size was calculated to be 75 patients. Assuming an exclusion or incomplete-measurement rate of approximately 20%, the planned sample size was increased to 90 patients.
Repeated cuff pressure measurements obtained from the same patients across different measurement times and target positions were analyzed using linear mixed-effects models with patient-level random intercepts. Measurement time was modeled as a categorical variable corresponding to T0, T1, and T2. The observational unit for these analyses was the individual cuff pressure measurement obtained at each predefined time point within each positioning cycle.
The cuff pressure dataset was organized in long format, such that each row represented 1 cuff pressure observation obtained at T0, T1, or T2. Each patient underwent 16 positioning cycles during the 2-day observation period, corresponding to 8 cycles per day; each positioning cycle included 3 cuff pressure measurements. Thus, each patient contributed 48 cuff pressure observations, yielding a total of 4944 observations from 103 patients. Positioning cycles, measurement time points, and patients were identified separately in the analytical dataset; repeated observations were linked using a unique patient identifier.
Predefined clinical events were assessed at T0, T1, and T2. Because no within-cycle variation in event status was observed across these time points, a single common indicator was retained for each event within each positioning cycle. Thus, clinical event analyses were based on 1648 positioning-cycle observations.
Patient-level random intercepts were used in the linear mixed-effects models to adjust for within-patient correlation arising from repeated cuff pressure measurements. Additional random effects for positioning cycle or time within the positioning cycle were not included because the primary analytical objective was to evaluate overall within-patient variation across repeated routine-care measurements, rather than cycle-specific variation.
Independent associations of measurement time, target position, measurement day, RASS score, and BMI with cuff pressure were evaluated using multivariable linear mixed-effects models. T0 was used as the reference category for measurement time, and the head-elevated supine position was used as the reference category for target position. The flat supine position was used only for standardized baseline measurements; it was not included as a target position in the analyses. Pairwise comparisons between measurement time points were performed using Bonferroni-adjusted post hoc contrasts derived from the linear mixed-effects models.
Additional exploratory analyses were performed according to predefined BMI categories (20 to < 25 kg/m2, 25 to < 30 kg/m2, and ≥ 30 kg/m2). Differences among BMI groups were evaluated using linear mixed-effects models analogous to the primary cuff pressure analyses. Temporal changes in endotracheal tube insertion depth across measurement time points were also analyzed using linear mixed-effects models with patient-level random intercepts, followed by Bonferroni-adjusted pairwise comparisons.
Patient-level event summaries were descriptively calculated as the proportion of patients who experienced at least 1 episode of each predefined clinical event during the observation period. For out-of-range cuff pressure, air leak alarm, and endotracheal tube displacement of at least 1 cm, separate multivariable logistic regression models were fitted using the 1648 positioning cycles as the observational units. Robust standard errors clustered at the patient level were used to adjust for the correlation arising from repeated positioning cycles within the same patient. Target position, measurement day, RASS score, and BMI were included as covariates. Measurement time was not included because event status did not vary across T0, T1, and T2 within the same positioning cycle.
Statistical analyses were performed using Python version 3.13.5. Data management and preparation were conducted using pandas version 2.2.3. Linear mixed-effects models were fitted using the statsmodels package (version 0.14.6) with patient-level random intercepts and restricted maximum likelihood estimation. Logistic regression models were estimated by maximum likelihood using patient-clustered robust covariance estimates.
Model convergence was confirmed for all fitted models. For the linear mixed-effects models, residual-versus-fitted plots and normal quantile-quantile plots were inspected to assess homoscedasticity and approximate residual normality. Multicollinearity among model covariates was assessed using variance inflation factors, all of which were below 1.6. No imputation was performed. Patients with incomplete cuff pressure measurement schedules were excluded prior to the final analysis; the 103 patients included in the final analysis had complete data for all variables used in the corresponding models.
Age was not included in the primary models because they focused on measurement time, target position, measurement day, RASS score, and BMI, consistent with the primary and secondary study objectives. To evaluate potential confounding by age, sensitivity analyses were performed by adding age as a continuous covariate (per 1-year increase) to the multivariable linear mixed-effects model for cuff pressure and to each multivariable logistic regression model for the predefined clinical events. The remaining covariates, reference categories, random-intercept specification for the cuff pressure model, and patient-clustered robust covariance specification for the clinical event models were retained unchanged.
Two-sided P-values < 0.05 were considered statistically significant for all analyses.
Results
Patient Characteristics
In total, 103 endotracheally intubated patients receiving invasive mechanical ventilation were included in the final analysis (Figure 1). The baseline demographic and clinical characteristics of the study population are summarized in Table 1. The mean age was 70.6 ± 13.5 years, and 54.4% of patients were men. The mean BMI was 28.5 ± 6.3 kg/m2.
Table 1.
Demographic and clinical characteristics of the study population.
| Variable | Value |
|---|---|
| Patients, n | 103 |
| Age, mean ± SD, years | 70.6 ± 13.5 |
| Sex, n (%) | |
| Female | 47 (45.6) |
| Male | 56 (54.4) |
| Body mass index, mean ± SD, kg/m2 | 28.5 ± 6.3 |
| Richmond Agitation-Sedation Scale score, mean ± SD | −0.10 ± 0.88 |
| Positive end-expiratory pressure, mean ± SD, cm H2O | 7.3 ± 1.5 |
| Pressure support, mean ± SD, cm H2O | 18.7 ± 4.3 |
| Tidal volume, mean ± SD, mL | 491.6 ± 83.4 |
n, number of patients; SD, standard deviation.
At the time of cuff pressure assessment, the mean RASS score was −0.10 ± 0.88, indicating an overall light level of sedation. Ventilator parameters included a mean positive end-expiratory pressure of 7.3 ± 1.5 cm H2O, pressure support of 18.7 ± 4.3 cm H2O, and tidal volume of 491.6 ± 83.4 mL. Although ventilator parameters were recorded at each cuff pressure measurement time point, they were collected for descriptive clinical characterization; they were excluded from repeated-measures analyses because ventilator-related effects were not prespecified study outcomes.
Repeated cuff pressure measurements obtained across all eligible positioning cycles during the 2-day observation period were included in the mixed-effects analyses.
Cuff Pressure Changes According to Measurement Time and Target Position
Endotracheal tube cuff pressure showed a significant time-dependent increase (P < 0.001). Pairwise comparisons indicated higher values at T1 and T2 than at T0 (both P < 0.001), with a modest increase from T1 to T2 (P = 0.007). However, the absolute magnitude of change was small, with a mean increase of 0.62 cm H2O from T0 to T2.
Across target positions, cuff pressure values were similar in the head-elevated supine, right lateral, and left lateral positions at all measurement time points; no statistically significant position-related differences were detected (all P > 0.05). Detailed cuff pressure values stratified by measurement time and target position are presented in Table 2.
Table 2.
Endotracheal tube cuff pressure according to measurement time and target position.
| Position | T0, cm H2O, mean ± SD |
T1, cm H2O, mean ± SD |
T2, cm H2O, mean ± SD |
|---|---|---|---|
| Overall | 27.67 ± 2.27 | 28.11 ± 2.89 | 28.29 ± 3.23 |
| Head-elevated supine | 27.66 ± 2.32 | 28.07 ± 2.85 | 28.34 ± 3.06 |
| Right lateral | 27.71 ± 2.25 | 28.12 ± 2.84 | 28.28 ± 3.30 |
| Left lateral | 27.63 ± 2.26 | 28.13 ± 2.96 | 28.27 ± 3.27 |
SD, standard deviation; T0, before repositioning in the flat supine position; T1, 1 minute after the target position was achieved; T2, 5 minutes after the target position was achieved.
Multivariable Analysis of Cuff Pressure
In the multivariable linear mixed-effects model, both measurement time and RASS score were independently associated with endotracheal tube cuff pressure. Relative to T0, cuff pressure was higher at T1 (β = 0.44 cm H2O; 95% confidence interval [CI], 0.31–0.58; P < 0.001) and increased further at T2 (β = 0.62 cm H2O; 95% CI, 0.49–0.75; P < 0.001).
RASS score showed a strong and consistent association with cuff pressure. Each 1-point increase in RASS score, reflecting lighter sedation or greater agitation, was associated with a 0.94-cm H2O increase in cuff pressure (95% CI, 0.86–1.02; P < 0.001).
In contrast, target position, measurement day, and BMI were not independently associated with cuff pressure after adjustment for covariates; effect estimates were near zero and CIs crossed the null value (Table 3).
Table 3.
Multivariable linear mixed-effects analysis of endotracheal tube cuff pressure.
| Variable | β coefficient (95% CI), cm H2O | P-value |
|---|---|---|
| T1 vs T0 | 0.44 (0.31–0.58) | < 0.001 |
| T2 vs T0 | 0.62 (0.49–0.75) | < 0.001 |
| Right lateral vs head-elevated supine | 0.02 (−0.12 to 0.16) | 0.751 |
| Left lateral vs head-elevated supine | −0.01 (−0.15 to 0.13) | 0.866 |
| Day 2 vs Day 1 | −0.01 (−0.12 to 0.10) | 0.875 |
| RASS score (per 1-point increase) | 0.94 (0.86–1.02) | < 0.001 |
| Body mass index (per kg/m2) | 0.02 (−0.03 to 0.08) | 0.442 |
β, regression coefficient; CI, confidence interval; RASS, Richmond Agitation-Sedation Scale; T0, before repositioning in the flat supine position; T1, 1 minute after the target position was achieved; T2, 5 minutes after the target position was achieved. Reference categories were T0 for measurement time, head-elevated supine for target position, and Day 1 for measurement day.
The relationship between RASS score and cuff pressure is illustrated in Figure 2.
Figure 2.
Relationship between Richmond Agitation-Sedation Scale (RASS) score and mean endotracheal tube cuff pressure across positioning cycles. Mean cuff pressure represents the average of T0, T1, and T2 measurements within each positioning cycle. Higher RASS scores were associated with higher cuff pressure values..
Additional Analyses: BMI Groups and Endotracheal Tube Insertion Depth
No statistically significant differences in cuff pressure were detected across BMI groups (P = 0.116), and no consistent trend was observed among BMI categories.
Endotracheal tube insertion depth showed a statistically significant increase over time; however, the magnitude of change was minimal. Pairwise comparisons demonstrated small but statistically significant differences between T0 and T1 (P = 0.034) and between T0 and T2 (P = 0.018); no significant difference was observed between T1 and T2 (P = 0.814). Detailed results are presented in Table 4.
Table 4.
Exploratory analyses according to body mass index groups and temporal changes in endotracheal tube insertion depth.
| Analysis | Category/time point | Mean ± SD | P-value |
|---|---|---|---|
| Cuff pressure by BMI group, cm H2O | BMI 20 to < 25 kg/m2 | 28.16 ± 2.66 | 0.116 |
| BMI 25 to < 30 kg/m2 | 27.45 ± 3.13 | ||
| BMI ≥ 30 kg/m2 | 28.46 ± 2.56 | ||
| Endotracheal tube insertion depth, cm | T0 | 21.55 ± 0.77 | < 0.05* |
| T1 | 21.58 ± 0.80 | ||
| T2 | 21.59 ± 0.81 |
BMI, body mass index; SD, standard deviation; T0, before repositioning in the flat supine position; T1, 1 minute after the target position was achieved; T2, 5 minutes after the target position was achieved.
Pairwise comparisons for endotracheal tube insertion depth: T0 vs T1 (P = 0.034), T0 vs T2 (P = 0.018), and T1 vs T2 (P = 0.814).
Predefined Clinical Events
The frequency of predefined clinical events was evaluated on both a positioning-cycle basis and a patient basis (Table 5). Positioning-cycle frequencies reflected the proportion of positioning cycles during which the corresponding event occurred, whereas patient-level frequencies represented the proportion of patients who experienced at least 1 episode of the corresponding event during the observation period.
Table 5.
Frequency of predefined clinical events.
| Event | Positioning-cycle-based frequency,% | Patient-based frequency,% |
|---|---|---|
| Air leak alarm | 9.5 | 35.9 |
| Out-of-range cuff pressure | 18.2 | 65.0 |
| Endotracheal tube displacement ≥ 1 cm | 7.9 | 40.8 |
Positioning-cycle-based frequencies were calculated from 1648 positioning cycles. Patient-level frequencies indicate the proportion of patients who experienced at least 1 episode of the corresponding event during the study period. Out-of-range cuff pressure was defined as cuff pressure < 20 cm H2O or > 30 cm H2O.
On a positioning-cycle basis, among 1648 positioning cycles included in the analyses, air leak alarm, out-of-range cuff pressure, and endotracheal tube displacement of at least 1 cm occurred in 157 (9.5%), 300 (18.2%), and 131 (7.9%) cycles, respectively.
On a patient basis, at least 1 episode of air leak alarm was observed in 35.9% of patients, out-of-range cuff pressure in 65.0%, and endotracheal tube displacement of at least 1 cm in 40.8%. Although these events were relatively infrequent at the positioning-cycle level, a substantial proportion of patients experienced at least 1 clinically relevant event during the observation period.
Predictors of Predefined Clinical Events
Multivariable logistic regression analyses with patient-clustered robust standard errors were performed using 1648 positioning-cycle observations to evaluate factors associated with the predefined clinical events (Table 6). These analyses were adjusted for the correlation arising from repeated positioning cycles within the same patient.
Table 6.
Multivariable logistic regression analyses for predefined clinical events using patient-clustered robust standard errors.
| Outcome | Variable | OR (95% CI) | P-value |
|---|---|---|---|
| Air leak alarm | Right lateral | 0.94 (0.70–1.27) | 0.694 |
| Left lateral | 0.96 (0.70–1.30) | 0.769 | |
| Day 2 | 1.51 (0.86–2.66) | 0.149 | |
| RASS score (per 1-point increase) | 0.84 (0.63–1.13) | 0.258 | |
| Body mass index (per kg/m2) | 1.04 (0.99–1.10) | 0.154 | |
| Out-of-range cuff pressure | Right lateral | 1.37 (1.04–1.81) | 0.025 |
| Left lateral | 1.27 (0.93–1.73) | 0.126 | |
| Day 2 | 0.95 (0.60–1.51) | 0.841 | |
| RASS score (per 1-point increase) | 7.21 (3.78–13.75) | < 0.001 | |
| Body mass index (per kg/m2) | 1.02 (0.98–1.06) | 0.295 | |
| Endotracheal tube displacement ≥ 1 cm | Right lateral | 0.81 (0.56–1.15) | 0.234 |
| Left lateral | 0.69 (0.48–1.00) | 0.050 | |
| Day 2 | 0.89 (0.45–1.76) | 0.742 | |
| RASS score (per 1-point increase) | 3.81 (2.36–6.15) | < 0.001 | |
| Body mass index (per kg/m2) | 1.04 (1.00–1.09) | 0.050 |
CI, confidence interval; OR, odds ratio; RASS, Richmond Agitation-Sedation Scale. Reference categories were the head-elevated supine position for target position and Day 1 for measurement day.
RASS score was not significantly associated with the occurrence of an air leak alarm in this dataset.
In contrast, higher RASS scores were strongly associated with increased odds of out-of-range cuff pressure. Each 1-point increase in RASS score was associated with substantially higher odds of out-of-range cuff pressure (odds ratio [OR], 7.21; 95% CI, 3.78–13.75; P < 0.001). Additionally, right lateral positioning was associated with a modest increase in the odds of out-of-range cuff pressure relative to the head-elevated supine position (OR, 1.37; 95% CI, 1.04–1.81; P = 0.025).
Similarly, for endotracheal tube displacement of at least 1 cm, higher RASS scores were independently associated with increased odds of displacement (OR, 3.81; 95% CI, 2.36–6.15; P < 0.001).
No statistically significant associations were identified for most other variables included in the models. However, borderline associations were observed for left lateral positioning (OR, 0.69; 95% CI, 0.48–1.00; P = 0.050) and BMI (OR, 1.04; 95% CI, 1.00–1.09; P = 0.050) in relation to endotracheal tube displacement of at least 1 cm; these findings should be interpreted cautiously (Table 6).
Sensitivity Analyses Including Age
Inclusion of age in the multivariable models did not materially alter the principal findings. In the age-adjusted linear mixed-effects model, age was not independently associated with cuff pressure (β = −0.010 cm H2O per year; 95% CI, −0.037 to 0.017; P = 0.468). The associations of T1 (β = 0.44 cm H2O; 95% CI, 0.31–0.58; P < 0.001), T2 (β = 0.62 cm H2O; 95% CI, 0.49–0.76; P < 0.001), and RASS score (β = 0.94 cm H2O per 1-point increase; 95% CI, 0.86–1.02; P < 0.001) with cuff pressure remained essentially unchanged.
Age was not independently associated with air leak alarm (OR, 1.01 per year; 95% CI, 0.99–1.04; P = 0.353), out-of-range cuff pressure (OR, 0.99 per year; 95% CI, 0.97–1.02; P = 0.595), or endotracheal tube displacement of at least 1 cm (OR, 0.99 per year; 95% CI, 0.96–1.02; P = 0.506). In age-adjusted models, RASS score remained associated with out-of-range cuff pressure (OR, 7.27; 95% CI, 3.86–13.70; P < 0.001) and endotracheal tube displacement of at least 1 cm (OR, 3.84; 95% CI, 2.47–5.98; P < 0.001). Right lateral positioning also remained associated with increased odds of out-of-range cuff pressure relative to the head-elevated supine position (OR, 1.37; 95% CI, 1.04–1.81; P = 0.025).
Overall, adjustment for age did not materially change the magnitude, statistical significance, or interpretation of the main findings. Detailed results of the age-adjusted sensitivity analyses are presented in Table 7.
Table 7.
Comparison of primary and age-adjusted sensitivity estimates for key associations.
| Outcome | Association | Primary model | Age-adjusted sensitivity model |
|---|---|---|---|
| Continuous cuff pressure | T1 vs T0 | β = 0.44 (0.31–0.58); P < 0.001 | β = 0.44 (0.31–0.58); P < 0.001 |
| Continuous cuff pressure | T2 vs T0 | β = 0.62 (0.49–0.75); P < 0.001 | β = 0.62 (0.49–0.76); P < 0.001 |
| Continuous cuff pressure | RASS score (per 1-point increase) | β = 0.94 (0.86–1.02); P < 0.001 | β = 0.94 (0.86–1.02); P < 0.001 |
| Continuous cuff pressure | Age (per year) | Not included | β = −0.01 (−0.04 to 0.02); P = 0.468 |
| Air leak alarm | RASS score (per 1-point increase) | OR = 0.84 (0.63–1.13); P = 0.258 | OR = 0.82 (0.60–1.12); P = 0.215 |
| Air leak alarm | Age (per year) | Not included | OR = 1.01 (0.99–1.04); P = 0.353 |
| Out-of-range cuff pressure | Right lateral vs head-elevated supine | OR = 1.37 (1.04–1.81); P = 0.025 | OR = 1.37 (1.04–1.81); P = 0.025 |
| Out-of-range cuff pressure | RASS score (per 1-point increase) | OR = 7.21 (3.78–13.75); P < 0.001 | OR = 7.27 (3.86–13.70); P < 0.001 |
| Out-of-range cuff pressure | Age (per year) | Not included | OR = 0.99 (0.97–1.02); P = 0.595 |
| Endotracheal tube displacement ≥1 cm | RASS score (per 1-point increase) | OR = 3.81 (2.36–6.15); P < 0.001 | OR = 3.84 (2.47–5.98); P < 0.001 |
| Endotracheal tube displacement ≥ 1 cm | Age (per year) | Not included | OR = 0.99 (0.96–1.02); P = 0.506 |
Values are β coefficients or odds ratios with 95% confidence intervals. β, regression coefficient; OR, odds ratio; RASS, Richmond Agitation-Sedation Scale; T0, before repositioning in the flat supine position; T1, 1 minute after the target position was achieved; T2, 5 minutes after the target position was achieved. The age-adjusted model retained the same covariates and reference categories as the corresponding primary model and included age as a continuous variable. For clinical-event outcomes, patient-clustered robust standard errors were used.
Discussion
In this prospective observational study, we evaluated short-term changes in endotracheal tube cuff pressure in mechanically ventilated ICU patients, according to measurement time, patient position, sedation level, and BMI. The study population generally exhibited light sedation, as reflected by the overall mean RASS score. The main findings were that cuff pressure significantly increased over time, whereas patient position was not independently associated with cuff pressure. Additionally, higher RASS scores, indicating lighter sedation or greater agitation, were independently associated with increased cuff pressure. These findings suggest that cuff pressure is a dynamic parameter primarily influenced by time-dependent and patient-related factors, rather than by patient position alone. Consistent with this observation, the small but statistically significant changes in endotracheal tube insertion depth over time were unlikely to be clinically meaningful, indicating that minor positional or temporal shifts in tube depth may not substantially affect cuff pressure.
Endotracheal tube cuff pressure significantly increased from T0 to T1 and T2. Although the changes were statistically significant, their absolute magnitude was small, with a mean increase of approximately 0.62 cm H2O from T0 to T2. Therefore, these findings should be interpreted as evidence of detectable short-term cuff pressure fluctuations under the present monitoring protocol, rather than definitive evidence of clinically important cuff pressure instability attributable to repositioning alone.
Furthermore, cuff pressure was readjusted to the recommended therapeutic range before each positioning cycle, which likely reduced the magnitude of the observed variation and may have influenced the temporal pattern of cuff pressure changes. Nevertheless, the findings support the concept that cuff pressure may fluctuate even over short observation intervals during routine ICU care, despite standardized baseline adjustment.
When cuff pressure values were compared across patient positions, no significant differences were observed among the head-elevated supine, right lateral, and left lateral positions. These findings suggest that patient position alone was not the primary contributor to cuff pressure variation under the conditions of the present study. Previous studies have identified variable effects of body position on cuff pressure. Lizy et al and Okgun Alcan et al reported measurable cuff pressure changes after patient repositioning [13,14]. Jalali et al also suggested that both body position and measurement time may influence cuff pressure [16]. Godoy et al similarly observed cuff pressure alterations after repositioning in mechanically ventilated patients [15]. In contrast, the absence of a significant position-specific effect in our cohort may be related to standardized baseline cuff pressure adjustment before each positioning cycle, the short measurement interval, and the use of standard high-volume, low-pressure cuffed endotracheal tubes. Nevertheless, right lateral positioning was associated with increased odds of out-of-range cuff pressure relative to the head-elevated supine position. This finding should be interpreted cautiously because patient position was not independently associated with cuff pressure as a continuous outcome. The increased odds observed with right lateral positioning may reflect transient mechanical changes, subtle tube movement, or patient-specific airway-tube interactions, rather than a consistent position-dependent increase in cuff pressure. Collectively, our findings suggest that cuff pressure should not be evaluated solely as a position-dependent parameter; they support repeated cuff pressure reassessment after repositioning during routine ICU care [4,5,11,12].
An important finding of this study was the independent association between sedation level and cuff pressure. Higher RASS scores, reflecting lighter sedation or greater agitation, were associated with increased cuff pressure. This relationship may be explained by increased patient movement, coughing, ventilator-patient asynchrony, or transient increases in airway and intrathoracic pressures in less deeply sedated patients. Previous studies have shown that cuff pressure may be affected by changes in airway pressure and other patient-related factors [6,9]. Thus, RASS score should be primarily interpreted as a marker of patient state within this observational dataset, rather than as evidence that a modified sedation strategy would necessarily reduce cuff pressure abnormalities. The observed associations may reflect multiple interrelated clinical factors, including patient movement, coughing, respiratory drive, ventilator-patient interaction, and underlying disease severity.
In addition to its association with cuff pressure as a continuous outcome, higher RASS scores were also independently associated with increased odds of out-of-range cuff pressure and endotracheal tube displacement of at least 1 cm. These findings suggest that lighter sedation or greater agitation may contribute not only to transient pressure fluctuations but also to clinically relevant cuff pressure deviations and tube movement during routine ICU care. In the present study, at least 1 episode of out-of-range cuff pressure was noted in 65.0% of patients during the observation period. Previous studies have similarly indicated that out-of-range cuff pressure is common in mechanically ventilated patients despite intermittent monitoring [9,10]. Collectively, these findings emphasize the importance of careful, repeated cuff pressure reassessment, particularly in patients with higher RASS scores or visible agitation.
In the present study, BMI was not independently associated with cuff pressure, and cuff pressure values were comparable across BMI groups. Although obesity can theoretically influence airway mechanics and intrathoracic pressure, BMI did not show a statistically significant independent association with short-term cuff pressure variability under the conditions established here. Different findings may be observed in more heterogeneous patient populations or over longer monitoring periods.
Out-of-range cuff pressure was frequently observed during the study period, particularly when evaluated on a patient basis. The distinction between positioning-cycle and patient-level event rates is clinically important: positioning-cycle rates reflect the frequency of abnormal findings across positioning cycles, whereas patient-level rates indicate the proportion of patients who experienced at least 1 episode during the observation period. In the present study, although abnormal events were relatively infrequent at the positioning-cycle level, a substantial proportion of patients experienced at least 1 episode of out-of-range cuff pressure, air leak alarm, or endotracheal tube displacement of at least 1 cm. Previous studies have similarly revealed that out-of-range cuff pressure is common in mechanically ventilated patients, even with intermittent monitoring [9,10]. Findings by Alzahrani et al also support the need for structured and repeated cuff pressure assessment in ICU patients [10]. Collectively, these findings suggest that intermittent single-time-point measurements can underestimate clinically relevant cuff pressure variability during routine ICU care.
The present findings further support the importance of careful and systematic airway monitoring, particularly in critically ill patients with fluctuating levels of sedation. In contrast to out-of-range cuff pressure and tube displacement, no independent predictors of air leak alarm were identified, which may partly reflect the relatively low event frequency and short observation period.
Strengths and Limitations
The present study has several strengths. The prospective observational design, standardized cuff pressure measurement protocol, repeated measurements at predefined time points, and use of mixed-effects models to adjust for within-patient correlation strengthen the reliability of the findings. Additionally, evaluations of clinical events on both a positioning-cycle basis and a patient basis provide a more comprehensive understanding of cuff pressure variability in routine ICU practice.
This study also has several limitations. First, it was conducted at a single center, which may limit the generalizability of the findings. Second, follow-up was limited to short-term measurements over a 2-day observation period, and continuous 24-hour cuff pressure monitoring was not performed. Third, although sedation level was assessed using the RASS, sedative drug type and dose were individualized according to routine ICU practice and were not controlled by the study protocol. Furthermore, sedation level may reflect disease severity, respiratory drive, patient-ventilator interaction, or other unmeasured clinical factors. Fourth, the sequence of patient positioning was not randomized but was determined according to routine ICU practice. Finally, although ventilator parameters were recorded at the time of cuff pressure assessment, coughing episodes, airway resistance, respiratory mechanics, and patient-ventilator asynchrony were not continuously monitored. The manometer was calibrated prior to initiation of measurements for each patient, but repeated connection and disconnection of the manual device may have transiently altered intracuff pressure or allowed small amounts of air loss. Additionally, operator-dependent variability cannot be completely excluded, although use of the same device, a standardized technique, trained ICU nurses, and patient-specific calibration likely minimized measurement-related error.
Accordingly, the findings should be interpreted within the context of the present study, including its single-center design, short-term observation period, nonrandomized routine-care positioning sequence, and the potential for residual confounding related to agitation, respiratory mechanics, coughing, and patient-ventilator interaction. The observed associations between RASS score and cuff pressure variability should not be interpreted as evidence of a causal relationship with sedation management strategies.
More broadly, these findings should be interpreted as observational associations within the study population and single-center ICU setting. They may not be fully generalizable to other ICU populations and do not support causal inference.
Conclusions
Endotracheal tube cuff pressure showed small but statistically significant short-term changes after repositioning in mechanically ventilated ICU patients, whereas no statistically significant independent association between patient position and cuff pressure was identified. Higher RASS scores were associated with greater cuff pressure variability and higher odds of out-of-range cuff pressure.
These findings support consideration of repeated cuff pressure reassessment after repositioning during routine ICU care, particularly in patients with higher RASS scores or greater agitation. However, the observed changes were modest and were identified under conditions of standardized baseline cuff pressure adjustment within a single-center observational study.
Acknowledgments
The authors thank the ICU staff for their valuable contributions to patient care and data collection.
Footnotes
Financial support: None declared
Conflict of interest: None declared
Publisher’s note: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher
Scientific Responsibility Statement: The authors declare that they are responsible for the scientific content of the article, including the study design, data collection, analysis, interpretation, manuscript preparation, and approval of the final version.
Declaration of Figures’ Authenticity: All figures submitted have been created by the authors who confirm that the images are original with no duplication and have not been previously published in whole or in part.
Data Availability
The datasets used and/or analyzed during the current study are not publicly available due to patient privacy considerations but are available from the corresponding author upon reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets used and/or analyzed during the current study are not publicly available due to patient privacy considerations but are available from the corresponding author upon reasonable request.