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| ORIGINAL ARTICLE |
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| Year : 2022 | Volume
: 1
| Issue : 2 | Page : 56-61 |
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Endotracheal tube cuff pressure changes with pneumoperitoneum and steep head down position in patients undergoing robotic urogynecological surgeries – A prospective observational study
Nagarapu Divya Meghana, Manoj Kumar Bharadwaj, Nitesh Goel, Seema Shukla
Department of Anaesthesia, Rajiv Gandhi Cancer Institute, New Delhi, India
| Date of Submission | 29-May-2022 |
| Date of Decision | 16-Jul-2022 |
| Date of Acceptance | 07-Aug-2022 |
| Date of Web Publication | 02-Dec-2022 |
Correspondence Address:
Dr. Nagarapu Divya Meghana
H. No 124, Pocket 1, Sector 25, Rohini, New Delhi - 110 085
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/jica.jica_15_22
Background: The abdominal insufflation in the laparoscopic surgery has been reported to result in an increase in endotracheal tube (ETT) cuff pressure (Pcuff). However, the effect of Trendelenburg, lithotomy and pneumoperitoneum on the ETT Pcuff in robotic urogynaecology surgeries are not well established. Aim: Analyse the changes in ETT cuff pressure during robotic urognaecological surgery. Primary Objective: 1. The changes in ETT cuff pressure after creation of pneumoperitoneum. 2. The changes in ETT cuff pressure after change in position of the patient. Secondary Objectives: 1. To correlate the changes in ETT cuff pressure with airway pressure. 2. To correlate the changes in ETT cuff pressure with BMI. Methods: Sixty patients undergoing elective robotic urogynaecology surgeries were enrolled in the study. ETT Pcuff during different time points was measured and analysed. Also, the change in ETT Pcuff was correlated with the airway pressure (Paw). Results: The difference in ETT Pcuff, before and after lithotomy, pneumoperitoneum and the Trendelenburg position were 1.1 ± 0.7 cmH2O, 4.6 ± 1.0 cmH2O and 1.8 ± 0.8 cmH2O respectively and were statistically significant (probability: P < 0.05). Results obtained after reversing patient position from Trendelenburg position to supine, abdominal deflation and from lithotomy to supine respectively were -2.2 ± 1.4 cmH2O, -4.1 ± 1.0 cmH2O and -0.4 ± 0.8 cmH2O respectively (P < 0.05). The Karl Pearson coefficient of correlation (r) between Pcuff and Paw after lithotomy, pneumoperitoneum, and Trendelenburg position respectively were 0.606, 0.661 and 0.309. Freidman's nonparametric repeated-measures analysis of variance (ANOVA) was used to analyze differences between related Pcuff values over different time points. Overall P value was significant (P < 0.00001). Conclusion: An increase in ETT cuff pressure is seen in robotic laparoscopic surgeries after abdominal insufflation, Trendelenburg position and lithotomy position.
Keywords: Endotracheal tube cuff pressure, pneumoperitoneum, robotic surgeries, Trendelenburg position
How to cite this article:
Meghana ND, Bharadwaj MK, Goel N, Shukla S. Endotracheal tube cuff pressure changes with pneumoperitoneum and steep head down position in patients undergoing robotic urogynecological surgeries – A prospective observational study. J Ind Coll Anesth 2022;1:56-61 |
How to cite this URL:
Meghana ND, Bharadwaj MK, Goel N, Shukla S. Endotracheal tube cuff pressure changes with pneumoperitoneum and steep head down position in patients undergoing robotic urogynecological surgeries – A prospective observational study. J Ind Coll Anesth [serial online] 2022 [cited 2023 May 30];1:56-61. Available from: https://www.jicajournal.in//text.asp?2022/1/2/56/362608 |
| Introduction | |  |
Airway management is the cornerstone of the anesthetic practice and has evolved from ventilation of an unprotected airway using a face mask to the ventilation of a protected airway using the cuffed endotracheal tube (ETT).[1] The main function of ETT cuff is to ensure pulmonary ventilation without air leak and to prevent aspiration of oropharyngeal and gastroesophageal contents into the lungs, by creating a seal between the patient's tracheal wall and the lateral wall of the cuff.[2],[3],[4],[5] The recommended range of ETT cuff pressure (Pcuff) is 20–30 cmH2O.[6] Despite the use of high-volume low-pressure cuffs (HVLP), complications related to over and under-inflation of the ETT cuff remain frequent.[7]
Over the past few years, rapid advances in surgery and anesthesia have made laparoscopic surgery a well-established procedure. In laparoscopic abdominal surgeries, despite the meticulous establishment of the cuff pressure within safe ranges immediately after tracheal intubation, significant alteration is still possible because of the maneuvers associated with laparoscopy such as pneumoperitoneum, steep head down, and lithotomy position. All these changes impact intraoperative pulmonary ventilation, can cause micro aspirations or damage to tracheal mucosal integrity, leading to postoperative airway complications. However, very few studies had shown the impact of pneumoperitoneum and patient posture on ETT cuff pressure.
In this present study, we evaluated the effect of pneumoperitoneum and patient positions like lithotomy and steep head down position on Pcuff. We also tried to find out the correlation between Pcuff with airway pressure (Paw) in patients undergoing robotic urogynecological surgeries as these procedures require creation of pneumoperitoneum and steep head down positioning of patients. This study is expected to bring out clarity regarding, the changes in the ETT Pcuff during the robotic abdominal surgery, allowing early detection and leading to optimal anesthetic care.
| Methodology | | |
The study was planned on 60 urogynecological cancer patients of either gender (the American Society of Anesthesia [ASA] grade 1 and 2), between 18–70 years of age, undergoing robotic urogynecological surgery after approval from institutional scientific and ethical committee. Primary outcome of the study was to observe change in ETT cuff pressure after creation of pneumoperitoneum whereas effect of patient posture on ETT cuff pressure was our secondary outcome. Patients having obstructive or restrictive lung disease, respiratory tract infection, altered laryngotracheal anatomy, history of tracheostomy, tracheal stenosis, tracheomalacia, surgery requiring nitrous oxide administration, cases requiring pressure control mode of ventilation and having ascites were not included in the study.
It was a prospective, observational study and was registered in the clinical trial registry of India, conducted over 1 year (August 2019–July 2020). To determine sample size, the mean and standard deviation (SD) obtained in the study conducted by Wu et al. were used and the effect size was found applying independent sample t-test using G*Power 3.1.9.221 G*Power 3.1 software.[8] With α error = 0.05, effect size d = 0.5, power (1-β err prob) = 0.80, we had a sample size of 51. Considering drop out, we enrolled total 60 patients.
After detailed pre-anesthetic check-up and relevant investigations, the anesthetic procedure was explained to the patient and written informed consent was recorded. In the operation theater, standard ASA noninvasive monitoring was applied and intravenous access was secured. All patients were induced using fentanyl 2 μg/kg, propofol 2 μg/kg intravenously, and bag mask ventilation checked. Thereafter, neuromuscular blockade was achieved by administering atracurium 0.7 mg/kg intravenously. After disappearance of train of four (TOF), patients were intubated with HVLP cuffed ETT of size 7.5 mm and 7 mm in males and females, respectively, and cuff was then inflated with 5 ml of room air. After confirming correct position of the ETT, Portex cuff manometer was connected to the pilot balloon using a three-way stopcock and the cuff pressure was adjusted using a 10 ml syringe to achieve cuff pressure of 26 cmH2O. All patients were mechanically ventilated using volume control mode @ tidal volume 5–7 ml/kg, respiratory rate 12–14/min, along with positive end expiratory pressure of 5cm H2O, to keep end tidal carbon-dioxide (ETCO2) in the range of 40 + 5 cm H2O. Intraoperatively, adequate depth of anesthesia (bispectral index <60) was maintained using sevoflurane with oxygen and air mixture along with injection propofol infusion at the rate of 0.1–0.2 mg/kg/min. Muscle relaxation was maintained using injection atracurium infusion at the rate of 0.5 mg/kg/h and monitored using peripheral nerve stimulator. The intraoperative and postoperative pain relief was managed using opioids and nonsteroidal anti-inflammatory drugs as per the nature of the surgery and pain response. All the patients were placed in lithotomy position with hips flexed 30 degrees from the trunk, and the legs abducted at 30 degrees from the midline. The knees were flexed until the lower legs are parallel to the torso with all the proper support needed at pressure points. The pneumoperitoneum was created by insufflation of carbon-dioxide (CO2), into the peritoneal cavity at a rate of 4–6 l/min to a pressure of 14 mmHg for visualization of the surgical field. Thereafter, intra-abdominal pressure (IAP) was maintained constant throughout the surgical duration by an AirSeal insufflation device. Then the patient was placed in Trendelenburg position at an angle of 45° followed by docking of robotic arms. During the study, ETT cuff pressure was monitored by attaching one end of high compliance tube to the ETT pilot balloon valve and the other end to manometer [Figure 1]. | Figure 1: Endotracheal tube cuff pressure monitoring using Posey portex cuff manometer connected to the pilot balloon using a three-way stopcock and high compliance extension tubing
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The ETT cuff pressure was adjusted to a baseline value (T0) of 26 cm H2O by adding or removing air from the cuff during a brief period of apnea with zero end-expiratory pressure by using Posey cuff inflator and manometer, and thereafter, it is continuously monitored and recorded throughout the surgery until the emergence of anesthesia. The volume of air within the ETT cuff was not modified during anesthesia, unless a significant leak was detected. ETT cuff pressure and parameters such as airway pressure, lung compliance were recorded at different time intervals: T0: After intubation, i.e., 26 cmH2O; T1: Just before lithotomy position; T2: Just after lithotomy position; T3: Just before pneumoperitoneum; T4: Just after pneumoperitoneum; T5: Five minutes after pneumoperitoneum; T6 (a, b, c, d, e…): Every 30 min thereafter; T7: Before the release of pneumoperitoneum; T8: After the release of pneumoperitoneum; T9: After supine position.
After completion of surgery, all anesthetic agents were switched off and the patients were oxygenated. Neuromuscular block was reversed using injection neostigmine 0.05 mg/kg and injection glycopyrrolate 10 μ/kg after the appearance of TOF ratio >0.9 for reversal of neuromuscular blockade. The trachea was then extubated when clinical signs of adequate neuromuscular recovery were achieved. The patient was then shifted to postoperative surgical intensive care unit for further management. The data obtained was compiled and analyzed.
Data were collected on a standard proforma during the procedure. Thereafter, it was scrutinized, codified and entered into the IBM SPSS Statistics, 24.0 software, www.spss.co.in for statistical analysis. The categorical variable like gender was compared using descriptive procedure and Chi-square test of association. Means of scale variables such as age and body mass index (BMI) are compared with independent sample t-test. Frequency distribution of surgery type, mean (SD) of surgical duration, duration of anesthesia, and duration of pneumoperitoneum were computed using descriptive statistics procedure. Comparison of Pcuff change, Paw change between time intervals within a group is done following Wilcoxon Signed Ranks test. Results are considered significant if P < .0005.
| Results | | |
The demographic and clinical profile of the patients is shown in [Table 1]. Age range was from 29 to 70 years, mean BMI was 27.0 ± 4.1 kgm2. The mean duration of surgery, pneumoperitoneum, and anesthesia was 212.9 ± 30.6, 192.0 ± 29.3, and 232.9 ± 30.6 min respectively. The mean Pcuff and Paw at different time points are presented in [Table 2]. The mean Pcuff after lithotomy (T2), pneumoperitoneum (T4), and Trendelenburg (T6a) position were 27.2 ± 0.8, 31.7 ± 1.7, and 33.8 ± 2.2 cmH2O, respectively. Post abdominal deflation the mean Pcuff decreased to 27.1 ± 0.7 cmH2O and further to 26.5 ± 0.7 cmH2O when the patient was shifted from lithotomy to supine position [Table 2] and [Figure 2]. The mean Paw after lithotomy (T2), pneumoperitoneum (T4) and Trendelenburg (T6a) position were 15.7 ± 2.4, 22.2 ± 3.3, and 26.2 ± 3.9 cmH2O, respectively. Post abdominal deflation the mean Pcuff decreased to 17.9 ± 2.5 cmH2O and further to 17.0 ± 2.2 cmH2O when the patient was shifted from lithotomy to supine position [Table 2] and [Figure 2]. The changes in Pcuff and Paw at different time intervals are presented in [Table 3]. The difference in ETT Pcuff, before and after lithotomy, pneumoperitoneum, and Trendelenburg position was 1.1 ± 0.7 (P = 0.001), 4.3 ± 1.0 cmH2O (P = 0.001), and 1.8 ± 0.8 cmH2O (P = 0.001), respectively, and were statistically significant (P < 0.05) [Table 3]. Amount of change in cuff pressure observed after reversing patient position from Trendelenburg position to supine, abdominal deflation, and from lithotomy to supine, respectively,were –2.2 ± 1.4 (P = 0.001), –4.1 ± 1.0 (P = 0.001), –0.4 ± 0.8 (P = 0.002)cmH2O, respectively (P < 0.05) [Table 3]. The difference in Paw, before and after lithotomy, pneumoperitoneum and Trendelenburg positionwere 1.7 ± 1.1 (P = 0.001), 6.4 ± 1.7 cmH2O (P = 0.001), and 3.8 ± 1.3cmH2O (P = 0.002), respectively, and were statistically significant (P < 0.05) [Table 3]. Amount of change in cuff pressure observed after reversing patient position from Trendelenburg position to supine, abdominal deflation, and from lithotomy to supine, respectively, were –2.5 ± 1.4 (P = 0.001), –5.8 ± 2.1 (P = 0.001), –1.0 ± 1.4 cmH2O (P = 0.001) respectively (P < 0.05) [Table 3]. The Karl Pearson coefficient of correlation (r) between Pcuff and Paw after lithotomy, pneumoperitoneum, and Trendelenburg position, respectively, was 0.606, 0.661, and 0.309 [Table 4]. | Table 2: Mean cuff pressure and airway pressure at different time points
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 | Figure 2: Mean Pcuff and Paw. Pcuff: Cuff pressure, Paw: Airway pressure
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 | Table 3: Changes in cuff pressure and airway pressure at different time intervals
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Since data were not normally distributed, Freidman's nonparametric repeated measures analysis of variance was used to analyze differences between related Pcuff values over different time points. Overall P value was significant (P < 0.00001). [Table 5] shows individual pairwise comparison of Pcuff values that were significantly different, P < 0.005. It implies that Pcuff differs significantly with respect to baseline and each other at different time points.[9] | Table 5: Freidman's nonparametric analysis of variance test to analyze changes in cuff pressure with duration of pneumoperitoneum and position
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| Discussion | | |
This study was planned to analyze and correlate the changes in ETT cuff pressure after pneumoperitoneum and steep head-down position during robotic urogynecological surgery. All patients were placed in a lithotomy position before creating pneumoperitoneum and putting them in a steep head-down position. We found a significant increase in Pcuff (P = 0.05) after lithotomy. Lithotomy is prone to movement of the pelvis and abdominal organs toward the head, as well as decreasing space for lung activity by flexion of the hip and knee lift to elevate the sacrum, thereby creating a relatively shorter lumbar vertebra height, decreasing lung compliance, and increasing airway resistance.[10] As a result, airway pressure increases in volume cycled ventilators to deliver set tidal volume. Rosero et al.[11] concluded that this increased airway pressure gets transmitted to the cuff, resulting in increased cuff pressure.
Kwon et al. also noted a significant increase in the Pcuff after the creation of pneumoperitoneum.[12] Geng et al. also suggested that the increased Paw during pneumoperitoneum was transmitted to the ETT cuff, resulting in increased Pcuff.[13] Our study also showed similar results where we found a significant increase in cuff pressure (4.6 1.0 cmH2O; P = 0.05) and airway pressure (6.6 1.6 cmH2O; P = 0.05) post pneumoperitoneum. [Table 3] also shows that the Pcuff value changes significantly as compared to its previous values in the same patient at different time points. It may be explained by the insufflation of CO2 into the abdomen during the pneumoperitoneum, which increases the IAP, pushing the diaphragm upward, resulting in restricted downward movement of the diaphragm during inspiration.[14] This leads to changes in respiratory mechanics, like increased paw. This Paw acts on the ETT cuff, resulting in increased Pcuff.
Pcuff (1.8 0.8 cmH2O; P = 0.05) and Paw (3.8 1.3 cmH2O; P = 0.05) also increased after changing positions to the steep Trendelenburg. This finding is also similar to the study conducted by Wu et al.[8] They noticed that the head-down position led to increases in Pcuff and Paw.[7] In Yildirim et al., they found that the increase in cuff pressure (P = 0.05) during pneumoperitoneum was greater in the Trendelenburg position.[15] Herway and Benumof reported that mediastinal shortening, cephalad movement of the carina, and the gravitational effect of the Trendelenburg position may be the underlying mechanisms behind the elevated cuff pressure.[16] Hence, the changes in the respiratory mechanics during pneumoperitoneum along with the gravitational effect of the Trendelenburg position may have resulted in a further increase in Pcuff after the Trendelenburg position. Trendelenburg positioning may also cause venous engorgement of the head and neck, which may reduce tracheal perfusion; thus, even a small increase in ETT Pcuff may compromise tracheal mucosa perfusion.
Our study also demonstrated that there is no change in Pcuff and Paw when IAP is maintained constant and factors known to increase Pcuff are avoided. In our study, all the patients underwent surgery in the Trendelenburg position as mentioned above. During this period, Pcuff and Paw were measured every 30 min. Furthermore, the IAP was maintained constant at 14 mmHg throughout the surgery using an air-seal insufflator device. In our study, we avoided intraoperative factors that could affect the ETT Pcuff, such as the use of Nitrous oxide (N2O) and changes in head-and-neck position.[17],[18] There is no study available in the literature supporting or contradicting our findings. However, Rauh et al. observed that ETT Pcuff increased with increasing the IAP from 10 mmHg to 15 mmHg.[19] Lehavi et al. noted that the Paw increased significantly with increased IAP, stating that there is a positive correlation between IAP and Paw.[20]
In our study, we found that the airway pressure and cuff pressure decreased with decreases in the degree of Trendelenburg position and IAP. The decrease in Pcuff along with the decrease in Paw can be explained by the changes in the respiratory mechanics caused by pneumoperitoneum and change in position, which were already discussed. As the cuff material in the PVC ETT was made of compliant material, and diffusible gases like N2O were not used in the surgery, the raised Pcuff may have resulted in increased Pcuff. The increasing pressure in the distal part of the cuff causes a redistribution of the air contained within the cuff away from the distal high-pressure area toward the proximal part of the cuff. Hence, there was only redistribution without any change in the volume of the air in the cuff. The Pcuff decreased to near baseline level as soon as the factors causing the rise in airway pressure were removed. We also observed that there was a significant positive correlation between ETT Pcuff and Paw during lithotomy (r = 0.606, P = 0.01), pneumoperitoneum (r = 0.661, P = 0.01), and Trendelenburg position (r = 0.309, P = 0.05). Our finding is in accordance with the study conducted by Rosero et al. They observed ETT Pcuff changes significantly in direct relation to the changes in the Paw (r = 0.26).[11] Geng et al. noticed that Pcuff and Paw are positively correlated in both the laparoscopic (r = 0.9431, P = 0.01) and the laparotomy groups (r = 0.8468, P = 0.01).[12]
During the surgical process, any position that limits diaphragmatic contraction leads to increased Paw. The lithotomy position and pneumoperitoneum both increase the IAP, thereby restricting the diaphragm's movement, and the Trendelenburg position, due to its gravitational effect, pushes the abdominal contents towards the diaphragm. All these result in increased Paw, which gets transmitted to the distal part of the ETT cuff, resulting in the redistribution of the same volume of air in the cuff toward the proximal part of the cuff, causing increased Pcuff.
The mean duration of surgery, pneumoperitoneum, and anesthesia were 212.9 30.6, 192.0 29.3, and 232.9 30.6 min, respectively. In our study, none of the cases extended for more than 4 h. Kako et al. suggest that fluctuations in Pcuff can be expected during prolonged surgical procedures and support the need for continuous monitoring of Pcuff.[18] Nordin proposed that lateral wall pressure was more important in the etiology of tracheal morbidity than the duration of intubation if this was <4 h.[21]
However, our study had some limitations. We used ETT cuffs of a single design from a single manufacturer. Therefore, our findings may not be applicable to other types of ETT. We did not assess clinical outcomes resulting from the increased Pcuff. However, others have found an increased incidence of sore throat related to an increase in ETT Pcuff during laparoscopy.
The results of the present study suggest that maneuvers associated with robotic laparoscopic surgery such as creation of pneumoperitoneum, lithotomy positioning, and Trendelenburg position may result in increased cuff pressure well above the recommended range, even after inflating the ETT cuff to the recommended range. This increase in cuff pressure is accompanied by a proportionate increase in airway pressure.
| Conclusion | | |
The measurement of cuff pressure with manometer is a simple and inexpensive procedure. Therefore, we suggest that ETT cuff pressure should be monitored routinely in all patients and readjustment should be done after both abdominal insufflation and Trendelenburg positioning to avoid complications due to high ETT cuff pressure. We also suggest readjusting the cuff pressure after abdominal deflation, and reversal of Trendelenburg position, so that under inflation and its subsequent complications can be prevented.
Financial support and sponsorship
Nil
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
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