Volume-controlled, pressure-controlled vs. pressure-controlled volume-guaranteed ventilations in improving respiratory dynamics during laparoscopic cholecystectomy: A prospective, randomized, comparative study

Sukriti Chowdhury; Asim Kumar Maiti; Suman Chattopadhyay; Debasish Bhar

doi:10.4103/bjoa.bjoa_254_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 7 | Issue : 1 | Page : 13-18

Volume-controlled, pressure-controlled vs. pressure-controlled volume-guaranteed ventilations in improving respiratory dynamics during laparoscopic cholecystectomy: A prospective, randomized, comparative study

Sukriti Chowdhury, Asim Kumar Maiti, Suman Chattopadhyay, Debasish Bhar
Department of Anesthesiology, Midnapore Medical College, West Bengal, India

Date of Submission	18-Nov-2022
Date of Decision	29-Dec-2022
Date of Acceptance	04-Jan-2023
Date of Web Publication	6-Mar-2023

Correspondence Address:
Debasish Bhar
Baalajee Ganges, Flat D305, 105D Bidhan Nagar Road, Kolkata 700067, West Bengal
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/bjoa.bjoa_254_22

Abstract

Introduction: Pressure-controlled volume-guaranteed (PCV-VG) mode has the advantage of both volume-controlled (VCV) and pressure-controlled ventilation (PCV). Our objective is to compare gaseous exchange and lung dynamic compliance (C_dyn) after pneumoperitoneum and just before desufflation in VCV, PCV, and PCV-VG mode in laparoscopic cholecystectomy (LC). Materials and Methods: A total of 105 patients undergoing LC under general anesthesia were randomly distributed to group V (received VCV), group P (PCV), and group PV (PCV-VG) as mode of ventilation. Two arterial blood samples were taken for blood gas analysis: after the pneumoperitoneum (T1) and right before abdominal desufflation (T2). Arterial partial oxygen pressure (PaO₂) and carbon dioxide (PaCO₂) levels, oxygen saturation (SpO₂) and end-tidal carbon dioxide were compared at these two points of time between the groups. Results: C_dyn was higher in group P (43.21 ± 4.4 mL/cmH₂O) compared with group V (39.18 ± 3.2 mL/cmH₂O) and PV (40.37 ± 2.45 mL/cmH₂O) at T2 (P < 0.001). PaO₂ was significantly higher (P < 0.001) in group P (197.50 ± 17.29 mm Hg) at T2 compared with group V (178.90 ± 23.7 mm Hg) and PV (183.47 ± 22.99 mm Hg). Furthermore, PaCO₂ was also significantly higher in Group P (40.19 ± 2.92 mm Hg) compared with group V (32.57 ± 2.09 mm Hg) and group PV (34.14 ± 3.27 mm Hg). Conclusion: PaO₂ and dynamic compliance are higher in pressure-controlled mode but, high PaCO₂ in pressure-controlled mode indicates inadequate ventilation. Therefore, pressure controlled volume guaranteed mode can be considered as a favorable ventilation strategy during LC because dynamic compliance and PaO₂ are higher than volume controlled ventilation and PaCO₂ is significantly less than pressure controlled mode.

Keywords: Compliance, laparoscopic cholecystectomy, oxygenation, ventilation

How to cite this article:
Chowdhury S, Maiti AK, Chattopadhyay S, Bhar D. Volume-controlled, pressure-controlled vs. pressure-controlled volume-guaranteed ventilations in improving respiratory dynamics during laparoscopic cholecystectomy: A prospective, randomized, comparative study. Bali J Anaesthesiol 2023;7:13-8

How to cite this URL:
Chowdhury S, Maiti AK, Chattopadhyay S, Bhar D. Volume-controlled, pressure-controlled vs. pressure-controlled volume-guaranteed ventilations in improving respiratory dynamics during laparoscopic cholecystectomy: A prospective, randomized, comparative study. Bali J Anaesthesiol [serial online] 2023 [cited 2023 Mar 27];7:13-8. Available from: https://www.bjoaonline.com/text.asp?2023/7/1/13/371181

Introduction

General anesthesia (GA) decreases vital capacity, functional residual capacity and compliance of the lung, particularly during laparoscopic procedures due to pneumoperitoneum, which increases intra-abdominal and intra-thoracic pressure.^[1] This may lead to closure of small airways leading to atelectasis of lung which results in various complications such as intra-operative hypoxia, barotrauma and volutrauma in patients with limited pulmonary reserve.^[2] Thus, proper mode of ventilation is important to reduce ventilation induced lung injury along with providing better oxygenation.

Volume-controlled ventilation (VCV) is regulated by tidal volume (VT) and respiratory rate (RR) as constant parameters with variable airway pressures particularly high peak inspiratory pressures (P-peak). Pressure-controlled ventilation (PCV) has constant inspiratory pressure while the VT depends on lung compliance and resistance. Decelerating inspiratory flow pattern in PCV, in contrast to a fixed flow pattern with VCV, reduces the incidence of barotrauma with high peak airway pressures.^[3] However, PCV has the risk of inadequate ventilation due to variable VT delivered due to changing lung compliance.^[4]

In order to mitigate the drawbacks of VCV (high peak airway pressure) and PCV (risk of inadequate ventilation), dual control ventilation has been developed in recent years to combine the advantages of VCV (constant VT) with the advantages of PCV (rapid, variable flow). Pressure-controlled volume guaranteed (PCV-VG) is a kind of dual controlled ventilation in which calculating the compliance of the lung, ventilator delivers the target VT at the lowest possible pressure using a decelerating flow pattern.^[3],[5]

A few studies compared PCV with PCV-VG mode in open abdominal surgery where no difference in terms of airway pressure, compliance and gas exchange were observed.^[6],[7] Regarding laparoscopic cholecystectomy (LC) there no clear evidence whether PCV-VG has any advantage over PCV and VCV in terms of respiratory dynamics and gaseous exchange. The primary aim of the study is to compare respiratory dynamics in terms of oxygenation (PaO₂, SpO₂), ventilation (PaCO₂, EtCO₂) and lung dynamic compliance (C_dyn) of lung after pneumoperitoneum and just before desufflation between PCV, VCV and PVC-VG mode.

Materials and Methods

After institutional ethical committee approval (MMC/IEC-2019/193 dated 28-01-2019) and informed patient consent this prospective, randomized study was conducted over a period of 12 months (July 2019 to June 2020) in the surgery operation theatre (OT) of this tertiary care institution. Study was conducted after approval from Clinical Trial Registry India (CTRI/2019/04/018720 dated 24.04.2019).

One hundred and five patients undergoing LC under GA were randomly distributed in 3 groups by giving sealed envelope containing a number from a computer-generated random number table. Group V received VCV, group P received PCV, and group PV received PCV-VG as their mode of ventilation. Non-smokers patients aged between 18 and 65 years of American Society of Anesthesiologist (ASA) physical status I and II were included in the study. Patients with preexisting lung diseases, respiratory tract infections in the past three weeks, body mass index (BMI) of >25, and pregnancy were excluded from the study. Patients whose ventilator mode were changed at any time during surgery and those who were deemed necessary to be converted to open procedure were excluded from the study.

Standard ASA monitoring were employed in all subjects. After securing intravenous (IV) line on the left forearm with a 18G cannula, premedication was administered with glycopyrrolate 4 mcg/kg and fentanyl 2 mcg/kg. Anesthesia was induced with propofol 2 mg/kg. Endotracheal intubation was facilitated using inj. atracurium 0.5 mg/kg. Maintenance of anesthesia was done with oxygen to nitrous oxide ratio of 40:60 with fresh gas flow of 6 L/min with isoflurane 0.8 vol%. Atracurium 0.1 mg/kg was administered as top-up to maintain adequate muscle relaxation assessed by neuromuscular monitor the surgery. At the end of the procedure, the neuromuscular block was reversed with neostigmine 0.05 mg/kg and glycopyrrolate 0.01mg/kg. Extubation was done when the patient was fully awake.

Ventilation was done using Carestation 620 Anesthesia Delivery System (GE Healthcare, Chicago, Illinois). In group V and PV, tidal volume was set according to body weight (8 mL/kg) where as in group P ventilation was started with airway pressure 12 cm of H₂O and adjusted accordingly to maintain tidal volume of 8 mL/kg (approx.). Inspiratory to expiratory (I:E) ratio was set to 1:2, inspired oxygen concentration (FiO₂) at 0.4, and positive end-expiratory pressure (PEEP) of 5 cm H₂O was fixed for all the patients.

During insufflation of the abdomen, the intra-abdominal pressure (IAP) was maintained between 12 and 14 mm Hg in all patients. After pneumoperitoneum was created, respiratory rate (RR) was adjusted to achieve an end tidal carbon dioxide (EtCO₂) between 32 and 38 mm Hg. Two arterial blood samples were taken for blood gas (ABG) analysis, one just after the pneumoperitoneum and reverse Trendelenburg (RT) position (T1) and one just before abdominal desufflation in RT position (T2).

Arterial oxygen tension (PaO₂), arterial carbon dioxide tension (PaCO₂), oxygen saturation (SpO₂) and EtCO₂ were compared at these points of time among the groups. Comparison of C_dyn, inspiratory VT and RR were also done at the time of arterial blood sampling. Heart rate (HR) and mean arterial pressure (MAP) were recorded and compared at the same time. While recording C_dyn, VT (inspiratory), RR, and HR ten measurements at point T1 and T2 were noted and average of these ten measurements was recorded as value at that point of time.

Sample size calculation was done on the assumption that difference of C_dyn among the groups more than 5 mL/cmH₂O is significant and standard deviation from previous study was found to be 5.75 and 8.18.^[8] Considering confidence interval (2-sided) (CI) 95% and power of the study 80% sample size in each group was estimated to be 32. Adding 10% dropout, patient needed in each group was estimated to be 35.

Data were recorded in MS Excel spreadsheet. Nominal variables were expressed as mean and standard deviation (SD). Frequencies and percentages were used for categorical variables. Results were analyzed by unpaired student’s t test for parametric data and Mann-Whitney U-test for non-parametric data when two groups were compared. One-way analysis of variance (ANOVA) for parametric data and Kruskal–Wallis test were utilized for nonparametric data were used while comparing three groups. Fisher’s exact test and chi-square test were used for categorical data as appropriate. A value of P < 0.05 was considered statistically significant. Data were analyzed by using the Statistical Package for the Social Science or SPSS software (IBM Corp. Released in 2015. IBM SPSS Statistics for Windows, version 23.0. Armonk, NY: IBM Corp.).

Results

One hundred and fourteen patients were screened for eligibility of the study. Seven patients did not meet the inclusion criteria and two patients refused to give consent, so nine patients were excluded and 105 patients were enrolled for the study. One patient in group P and two patients in group V were converted to open procedure due to technical difficulty by surgeon. No patient in group PV was excluded from the study [Figure 1].

Figure 1: Flow chart showing patient disposal in the study

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There was no difference among the groups regarding age, weight, BMI, sex, ASA grade, duration of surgery and duration of anesthesia [Table 1]. HR at T2 was significantly more in group P compared with group V (P = 0.016). MAP at both T1 and T2 were comparable among the groups [Table 2]. VT was significantly less in group P compared with other groups at T1 (P = 0.036), however, there was no significant difference among the groups at T2. RR was significantly high in group P compared with other groups at T2 (P = 0.016). C_dyn at T2 was significantly high (P < 0.001) in group P (43.21 ± 4.41 mL/cmH₂O) compared with other groups (V 39.18 ± 3.20 and PV 40.37 ± 2.45 mL/cmH₂O) (P < 0.001), as seen in [Table 3].

Table 1: Demographic profile

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Table 2: Hemodynamic parameters (data presented as mean and standard deviation)

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Table 3: Respiratory dynamics (data presented as mean and standard deviation)

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PaO₂ was significantly more (P < 0.001) in group P (197.50 ± 17.29 mm Hg) at T2 compared with group V and PV (178.90 ± 23.70 and 183.47 ± 22.99 mm Hg, respectively). In addition, PaCO₂ was higher in group P and PV (35.16 ± 3.16 and 33.69 ± 1.62 mm Hg, respectively) compared with group V at T1 (36.16 ± 2.20 mm Hg), however, at T2 PaCO₂ was significantly higher (P < 0.001) in group P (40.19 ± 2.92 mm Hg) compared with Group V (32.57 ± 2.09 mm Hg) and group PV (34.14 ± 3.27 mm Hg). No difference was observed in PaCO₂ at T2 between group V and PV (P = 0.06). We also found no significant difference regarding SpO₂ and EtCO₂ among the groups at any point of time [Table 4]. No adverse effects or complications were recorded in any of the patients in the intra operative and postoperative period.

Table 4: Parameters of oxygenation and ventilation

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Discussion

LC is nowadays preferred over open cholecystectomy as it has six-fold less postoperative pulmonary complications.^[9] Pneumoperitoneum created during laparoscopy shifts the diaphragm in cephaloid direction with reduction of pulmonary compliance by 25%–40% and significant increase in the airway pressure.^[10] Demonstration of stress injury following increased airway pressure and information from meticulous study of pressure volume curve have modified the concept of safe range of volume and pressure change during pneumoperitoneum specially in patients with underlying lung disorder. Lung protective strategy for ventilation, application of PEEP and recruitment strategy are implemented to improve oxygenation and minimize changes developed due to pneumoperitoneum.^[11]

Several studies have been conducted to compare the effects of PCV and VCV on respiratory mechanics during different types of surgery and found that PCV mode was associated with lower P-peak and higher C_dyn compared with VCV.^{[12],[13],[14],[15],[16],[17]} Some studies have observed significant increase in oxygenation (high PaO₂) and better ventilation with PCV mode, whereas others found no significant difference regarding oxygenation and ventilation.^[18],[19] Systemic review and meta-analysis has observed similar result while comparing the studies with PCV and VCV.^[20]

Recently, one meta-analysis comparing VCV and PCV-VG have observed lower P-peak, P-plateau and higher C_dyn in PCV-VG mode. Improved oxygenation in PCV-VG mode has been shown in most of the studies in this meta-analysis, whereas some studies have not found any significant difference in oxygenation.^[21]

In the present study we have assessed respiratory dynamics after creation of pneumoperitoneum and just before desufflation (both in RT position) which gives us a better idea about the effect of ventilation mode on respiratory dynamics and gas exchange. VT was initially low in PCV mode compared with other modes but at the end there was no significant difference among the three modes. Similar observation was observed by Kothari and Baskaran,^[8] where at the beginning VT was low in PCV mode compared with VCV and PCV-VG mode, but the difference was not significant in their study.

Lee et al.^[22] compared these three modes of ventilation in gynecological laparoscopic surgeries in Trendelenburg position and observed C_dyn to be significantly high in PCV and PCV-VG mode than VCV. This difference may be attributed to head down position in gynecological surgeries.^[23] Dion et al.^[24] in another study compared these three modes in laparoscopy assisted bariatric surgery. They found lower VTs in PCV mode compared with VCV and PCV-VG, which was similar to present study.

We also found that PaO₂ was significantly higher in PCV mode before desufflation compared with other two groups. No significant difference was observed between VCV and PCV-VG mode at T2 but PaO₂ value was higher in PCV-VG mode. This is different from a previous study where they have not found any difference in PaO₂ in three different modes of ventilation. This may be due to the difference in timing of doing arterial blood gas analysis in the two studies. They measured PaO₂ at the time of intubation, 15 min after insufflation and 15 after desufflation whereas in the present study it was measured just after insufflation and just before desufflation (both in RT position).

Lee et al.^[22] also have not observed any difference in PaO₂ among the three modes of ventilation up to 60 min after insufflation. In our study, PaO₂ was measured after 90 min because mean duration of surgery was more than 90 min in all groups. Trendelenburg position and difference in timing of ABG may be the reason for the difference in observation.

Dion et al.^[24] measured no significant difference in PaO₂at 20 min after insufflation but value of PaO₂ was higher in PCV and PCV-VG compared with VCV mode.

In the present study PaCO₂ was higher in PCV and PCV-VG mode at the beginning of insufflations (T1) but before desufflation (T2) only PCV mode had a higher PaCO_2. No significant difference was observed between VCV and PCV-VG at that time (T2). Previous study had different observation regarding PaCO₂ and EtCO2, where they found lower value in PCV mode.^[8] Difference in timing of arterial blood sampling may be attributable for this difference. Other reports also observed no difference in PaCO₂ while comparing these three modes in laparoscopic gynecological surgery and laparoscopy assisted bariatric surgery.^[22],[24]

Previous studies comparing VCV and PCV in LC have difference in observations. Some has reported better oxygenation in PCV mode in both obese patients^[18],[19] and nonobese patients.^[13] However, one study has reported better oxygenation in VCV mode.^[25] Peak airway pressure was low or C_dyn was higher in PCV mode in all the studies as in the present study. Studies comparing VCV and PCV-VG in different types of surgery except LC have reported lower C_dyn in PCV-VG mode similar to present study.^{[26],[27],[28],[29]} No difference in oxygenation was observed in previous studies except one where they observed significantly higher PaO₂ in PCV-VG mode used for obese patient in Trendelenburg position.^[29] In the present study, no significant difference was observed regarding oxygenation between VCV and PCV-VG.

Comparing only two time points (T1 and T2) throughout pneumoperitoneum is main limitation of the present study. Pressure parameters (P-peak, P-mean, and P-plateau) were also not compared. Future study comparing these three modes of ventilation is to be done for evaluation of the efficacy of the ventilation modes in obese and chronic obstructive lung disease patients undergoing LC.

Conclusion

From the observations and analyses of the present study it can be inferred that in patients undergoing LC the dynamic compliance and oxygenation (PaO2) is better in the PCV and PCV-VG modes than VCV mode. But, the PaCO₂ is highest in PCV mode indicating inadequate ventilation. Therefore, pressure controlled volume guaranteed mode can be considered as a favorable ventilation strategy during LC as it is a controlled ventilation mode combining the advantages of volume control and the clinical benefits of pressure controlled mode for maintenance of oxygenation and ventilation during pneumoperitoneum in LC.

Financial support and sponsorship

Not applicable.

Conflicts of interest

There are no conflicts of interest.

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