This study showed no significant difference between the volume control and pressure control groups at 10, 20, and 30 min after the ventilation initiation. According to the literature review, it seems that there is no similar study investigating the effect of two volume and pressure modes on endotracheal tube cuff pressure, and this study is the first study to investigate the effect of two modes of volume and pressure ventilation on cuff pressure. Previous studies have indicated that the maximum airway pressure is significantly lower in the pressure control ventilation mode compared to the volume control ventilation mode. For example, a study conducted by Tyagi et al. (2011) comparing volume control and pressure control ventilation in patients undergoing laparoscopic cholecystectomy demonstrated that airway pressure was significantly lower in pressure control mode than in volume control mode [
11]. On the other hand, the endotracheal tube cuff pressure is affected by airway pressure. In another study by Rosero et al. (2018) on the effects of increased airway pressure on endotracheal tube cuff pressure, it was found that it was significantly increased by increasing the maximal airway pressure [
12]. In the study of Parsian et al. (2019), a significant positive relationship between airway pressure and ETCP was observed [
13]. Another factor influencing ETCP is body position. In this regard, Bahonar et al. (2022) studied the effect of body position and bed head angle on intra-abdominal pressure and ETCP. The results of this study showed that the pressure of the ECTP in the lying position on the opposite side of the device is significantly higher than in other positions. Also, no significant relationship was observed between intra-abdominal pressure and tracheal tube cuff pressure [
14]. Oğurlu et al. (2010) also compared volume and pressure control modes in laparoscopic pelvic surgery patients. Their results showed that airway pressure was significantly higher in the volume control group than in the pressure control group [
15]. However, this study showed no significant difference in cuff pressure between the volume control and pressure control groups. This insignificance of the difference in cuff pressure between the two groups in this study may be due to the relatively short measurement time of the cuff pressure (cuff pressure in both groups was measured 10, 20, and 30 min after the mechanical ventilation initiation). Also, in this research, patients with normal lung function were enrolled. Therefore, their lung compliance and airway resistance were normal. While many ICU patients, due to reduced compliance, have high pressure during inhalation in volume ventilation, which can affect the cuff pressure. Airway resistance changes also affect cuff pressure [
16]. Therefore, further studies on various patients that include the effect of lung compliance and airway resistance are required.
Based on the current study results, the passage of time significantly reduced cuff pressure in both volume control and pressure control groups. So, both groups had the lowest cuff pressure at 30 min after ventilation.
According to the results of the study by Sole et al. (2011), which evaluated an intervention to maintain cuff pressure in patients undergoing mechanical ventilation, the passage of time reduced cuff pressure significantly [
4]. In their study, Saxena et al. (2022) investigated changes in ETCP during laparoscopic bariatric surgery. The results of this study showed that the ETCP varies significantly during this surgery. So that this pressure was significantly reduced during the removal of gastric calibration tubes (GCTs) and the release of the carbo peritoneum [
17]. Also, the results of the study by Athiraman et al. (2015), in which they examined cuff pressure changes with position change in patients undergoing neurologic surgery, showed that cuff pressure decreased significantly over time [
18]. The results of the current study are in line with the results of these studies. Several factors affect reducing ETCP over time. For example, the endotracheal tube material can effectively maintain pressure. Also, previous studies have shown that each cuff pressure measurement with a manometer can decrease the cuff pressure, and the greater number of cuff pressure measurements causes the cuff pressure to decrease further. Nseir’s study (2009) explains the relationship between the length of intubation time and the pressure drop of the endotracheal tube cuff so that the high-volume cuffs become porous with low pressure over time. Lack of reception of sedation drugs in undergoing intubation patients, coughing and lack of coordination with the ventilator also increases the airway pressure, and this discharge the air of the cuff and reduce its pressure over time [
19].