A comparison of pressure-controlled and volume-controlled ventilation for laparoscopic cholecystectomy

Comparative study of ventilation techniques with supraglottic airway devices in cats: volume-controlled vs pressure-controlled techniques

OBJECTIVES

This study compared the effectiveness of a new supraglottic airway device (SGAD) in cats undergoing anaesthesia using two types of mechanical ventilation: volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV).

METHODS

A total of 13 healthy cats (five male, eight female; median age 2 years [range 1-3]) were randomly allocated to either VCV or PCV. Five tidal volumes (6, 8, 10, 12 and 14 ml/kg) and five peak inspiratory pressures (4, 5, 6, 7 and 8 cmH2O) were randomly applied with a minute ventilation of 100 ml/kg/min. Various parameters, such as blood pressure, gas leakage, end-tidal CO2 (ETCO2) and work of breathing (WOB), were measured while using VCV or PCV.

RESULTS

The occurrence of hypotension (mean arterial blood pressure <60 mmHg) was slightly less frequent with VCV (38 events, 65 ventilating sessions) than with PCV (40 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.429). The number of leakages did not differ between the VCV group (3 events, 65 ventilating sessions) and the PCV group (3 events, 65 ventilating sessions) (P = 1.000). Hypercapnia was identified when using VCV (10 events, 65 ventilating sessions) less frequently than when using PCV (17 events, 65 ventilating sessions), but this difference did not reach statistical significance (P = 0.194). The study found a significantly higher WOB in the PCV group compared with the VCV group (P <0.034).

CONCLUSIONS AND RELEVANCE

The present results suggested that both VCV and PCV can be used with an SGAD during anaesthesia, with VCV preferred for prolonged mechanical ventilation due to its lower workload. Adjusting tidal volume or inspiratory pressure corrects hypercapnia.

Comparison of the effect of pressure control and volume control ventilation on endotracheal tube cuff pressure in patients undergoing general anesthesia and mechanical ventilation: a parallel randomized clinical trial

BACKGROUND

Endotracheal intubation and mechanical ventilation are prevalent interventions in the operating room and intensive care unit. Recently, the complications of endotracheal tube cuff pressure have been a topic of interest. Therefore, this study compared the effect of pressure control and volume control ventilation modes on the endotracheal cuff pressure rate in patients undergoing general anesthesia and mechanical ventilation.

METHODS

In this triple-blinded randomized clinical trial, 50 patients undergoing open limb surgery and inguinal hernia were allocated to two groups of 25 based on inclusion criteria. After intubation, one group underwent ventilation on the pressure control ventilation mode, and the other underwent ventilation on the volume control ventilation mode. In both groups, using a manometer, the cuff's pressure was first adjusted in the range of 25-30 cm of water. Then, the cuff pressure was measured at 10, 20, and 30 min intervals. The data were statistically analyzed using independent t-test, and two-way repeated measures ANOVA.

RESULTS

The present study's findings showed that cuff pressure has significantly decreased over time in both study groups (F = 117.7, P < 0.001). However, a repeated measures ANOVA with a Greenhouse-Geisser correction showed no interaction between time and groups (F = 0.019, P = 0.98). The two groups had no significant difference in cuff pressure (F = 0.56, P = 0.458).

CONCLUSION

Since the cuff pressure has been significantly reduced in both groups over time, continuous monitoring of endotracheal tube cuff pressure in patients undergoing mechanical ventilation is essential. Therefore, it is suggested to keep the cuff pressure within the recommended range to prevent complications resulting from cuff pressure reduction, such as aspiration and ventilation decrease.

TRIAL REGISTRATION

The study was registered in the Iranian Registry of Clinical Trial on 23/02/2019 (trial registration number: IRCT20181018041376N1).

Effects of pressure- and volume-controlled ventilation on the work of breathing in cats using a cuffed endotracheal tube

Background and Aim:

Mechanical ventilation is essential for supporting patients’ respiratory function when they are under general anesthesia. For cats with limited lung capacity, the different effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on respiratory function remain elusive. The objective of the present study was to compare the efficacy of VCV and PCV in cats under general anesthesia using a cuffed endotracheal tube (ETT).

Materials and Methods:

Twelve healthy cats were randomly allocated to either a VCV or PCV group. Five tidal volumes (6, 8, 10, 12, and 14 mL/kg) were randomly applied to assess the efficacy of VCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Peak inspiratory pressures (4, 5, 6, 7, and 8 mmHg) were randomly applied to assess the efficacy of PCV, and respiratory rates were adjusted to achieve a minute ventilation of 100 mL/kg/min. Blood pressure, gas leakages, and end-tidal CO₂ were recorded from 60 trials for airway control during the use of VCV or PCV. Data were compared using Fisher’s exact test with a significance level of p<0.05.

Results:

Leakages did not differ between VCV (1/60 events) and PCV (0/60 events; p=0.500). Hypercapnia was identified when using VCV (6/60 events) less frequently than when using PCV (7/60 events; p=0.762), but did not reach statistical significance. Hypotension (mean arterial blood pressure <60 mmHg) occurred less frequently with VCV (0/60 events) than with PCV (9/60 events; p=0.003). Moreover, VCV provided a significantly lower work of breathing (151.10±65.40 cmH₂O mL) compared with PCV (187.84±89.72 cmH₂O mL; p<0.05).

Conclusion:

VCV in cats using a cuffed ETT causes less hypotension than PCV. It should be noted that VCV provides a more stable tidal volume compared with PCV, resulting in a more stable minute volume. Nonetheless, VCV should not be used in patients with an airway obstruction because higher peak airway pressure may occur and lead to lung injury.

Effect of Various Modes of Mechanical Ventilation in Laparoscopic Cholecystectomies on Optic Nerve Sheath Diameter and Cognitive Functions

Aim: In this study, we aim at investigating the effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) modes on changes in the optic nerve diameter and cognitive functions in laparoscopic cholecystectomy operations. Materials and Methods: Sixty patients who underwent laparoscopic cholecystectomy were randomly divided into two groups based on the mode of mechanical ventilation provided: Group P; PCV, Group V; VCV. Optic nerve sheath diameter was measured when the patient was awake (T0), in the 10th minute after induction (T1), in the 10th minute after the initiation of gas insufflation (T2), when maximum gas pressure was reached in the reverse-Trendelenburg position (T3), and pre-extubation (T4). Partial oxygen saturation (PaO₂), PCO₂, end-tidal carbon dioxide (ETCO₂), and peak airway pressure (pPEAK) were also recorded. A Mini-Mental State Examination (MMSE) was conducted on patients preoperatively and in the postoperative third month. Results: Between the groups, a statistically significant difference was found in Group P compared with Group V in terms of optic nerve diameter at measurement times T1 (P < .05). In the intragroup comparison, a significant difference was found in the initial values in all measurements except for measurement times T0 and T4 in both Group P and Group V (P < .05). pPEAK values were identified to be statistically significantly lower in Group P than Group V at all measurement times (P < .05). No difference was identified in the MMSE scores in the intergroup and intragroup comparisons. Conclusion: Laparoscopic cholecystectomy increases the optic nerve diameter due to the mechanical and systemic effects of the operation, and the PCV mode can be preferred. Clinical Trial Number: NCT04413903.

A clinical trial of volume- versus pressure-controlled intraoperative ventilation during laparoscopic bariatric surgeries

BACKGROUND

Intra-operative ventilation is often challenging in patients with morbid obesity undergoing bariatric surgery.

OBJECTIVES

To test the noninferiority of pressure-controlled ventilation (PCV) to volume-controlled ventilation (VCV) in respiratory mechanics.

SETTING

Bariatric Surgery Center, Iran.

METHODS

In a randomized open-labeled clinical trial, 66 individuals with morbid obesity undergoing laparoscopic bariatric surgeries underwent intraoperative ventilation with either PCV or VCV. The measurements taken were peak and mean airway pressures (H₂O), partial pressure of arterial oxygen (PaO₂), partial pressure of arterial carbon dioxide (PaCO₂) and end-tidal carbon dioxide (CO₂). We additionally collected pulse-oximetric oxygen saturation, inspiratory concentration of oxygen (FiO₂), and hemodynamic variables. Data were analyzed with repeated measures over the time of intubation, after peritoneal insufflation, and every 15 minutes, thereafter up to one hour.

RESULTS

PCV mode was successful to sustain adequate ventilation in 97% of the patients, which was similar to the 94% success rate of the VCV mode. Peak airway pressure increased 6 cmH₂O and end-tidal CO₂ rose by 5 mm Hg after abdominal insufflation in both groups (P = .850 and .376). Alveolar-arterial oxygen gradient similarly increased within 30 minutes after tracheal intubation both in PCV and VCV groups, with small trend of being higher in the VCV group. The ratio of dead space to tidal volumes (VD/VT) did not have a meaningful change (P = .724).

CONCLUSION

PCV was noninferior to VCV during laparoscopic bariatric surgery. Either mode of ventilation could be alternatively used during the anesthesia care of these patients.

[Comparison of volume-controlled and pressure-controlled ventilation on respiratory mechanics in laparoscopic bariatric surgery: randomized clinical trial]

BACKGROUND

It is not clear which mechanical ventilation mode should be used in bariatric surgery, one of the treatment options for patients with obesity.

OBJECTIVES

To compare volume-controlled ventilation and pressure-controlled ventilation in terms of respiratory mechanics and arterial blood gas values in patients undergoing laparoscopic bariatric surgery.

METHODS

Sixty-two patients with morbid obesity scheduled for gastric bypass were included in this study. Their ideal body weights were calculated during preoperative visits, and patients were divided into two groups, volume-controlled ventilation and pressure-controlled ventilation. The patients were ventilated in accordance with a previously determined algorithm. Mechanical ventilation parameters and arterial blood gas analysis were recorded 5 minutes after induction, 30 minutes after pneumoperitoneum, and at the end of surgery. Also, the dynamic compliance, inspired O₂ pressure/fractional O₂ ratio, and alveolar-arterial oxygen gradient pressure were calculated.

RESULTS

Peak airway pressures were lower in patients ventilated in pressure-controlled ventilation mode at the end of surgery (p = 0.011). Otherwise, there was no difference between groups in terms of intraoperative respiratory parameters and arterial blood gas analyses.

CONCLUSIONS

Pressure-controlled ventilation mode is not superior to volume-controlled ventilation mode in patients with laparoscopic bariatric surgery.

Comparison of pressure- and volume-controlled ventilation during laparoscopic colectomy in patients with colorectal cancer

This study investigated the differences in airway mechanics and postoperative respiratory complications using two mechanical ventilation modalities and the relationship between biomarkers and postoperative respiratory complications in patients with colorectal cancer who underwent laparoscopic colectomy. Forty-six patients with colorectal cancer scheduled for laparoscopic colectomy were randomly allocated to receive mechanical ventilation using either volume-controlled ventilation (VCV) (n = 23) or pressure-controlled ventilation (PCV) (n = 23). Respiratory parameters were measured and plasma sRAGE and S100A12 were collected 20 minutes after the induction of anesthesia in the supine position without pneumoperitoneum (T1), 40 minutes after 30° Trendelenburg position with pneumoperitoneum (T2), at skin closure in the supine position (T3), and 24 hours after the operation (T4). The peak airway pressure (Ppeak) at T2 was lower in the PCV group than in the VCV group. The plateau airway pressures (Pplat) at T2 and T3 were higher in the VCV group than in the PCV group. Plasma levels of sRAGE at T2 and T3 were 1.6- and 1.4-fold higher in the VCV group than in the PCV group, while plasma S100A12 levels were 2.6- and 2.2-fold higher in the VCV group than in the PCV group, respectively. There were significant correlations between Ppeak and sRAGE, and between Ppeak and S100A12. There were also correlations between Pplat and sRAGE, and between Pplat and S100A12. sRAGE and S100A12 levels at T2 and T3 showed high sensitivity and specificity for postoperative respiratory complications. Postoperative respiratory complications were 3-fold higher in the VCV group than in the PCV group. In conclusion, during laparoscopic colectomy in patients with colorectal cancer, the peak airway pressure, the incidence of postoperative respiratory complications, and plasma sRAGE and S100A12 levels were lower in the PCV group than in the VCV group. Intra- and postoperative plasma sRAGE and S100A12 were useful for predicting the development of postoperative respiratory complications.

Comparison of volume-controlled and pressure-controlled ventilation on respiratory mechanics in laparoscopic bariatric surgery: randomized clinical trial

Background

It is not clear which mechanical ventilation mode should be used in bariatric surgery, one of the treatment options for patients with obesity.

Objectives

To compare volume-controlled ventilation and pressure-controlled ventilation in terms of respiratory mechanics and arterial blood gas values in patients undergoing laparoscopic bariatric surgery.

Methods

Sixty-two patients with morbid obesity scheduled for gastric bypass were included in this study. Their ideal body weights were calculated during preoperative visits, and patients were divided into two groups, volume-controlled ventilation and pressure-controlled ventilation. The patients were ventilated in accordance with a previously determined algorithm. Mechanical ventilation parameters and arterial blood gas analysis were recorded 5minutes after induction, 30minutes after pneumoperitoneum, and at the end of surgery. Also, the dynamic compliance, inspired O₂ pressure/fractional O₂ ratio, and alveolar-arterial oxygen gradient pressure were calculated.

Results

Peak airway pressures were lower in patients ventilated in pressure-controlled ventilation mode at the end of surgery (p = 0.011). Otherwise, there was no difference between groups in terms of intraoperative respiratory parameters and arterial blood gas analyses.

Conclusions

Pressure-controlled ventilation mode is not superior to volume-controlled ventilation mode in patients with laparoscopic bariatric surgery.

Impact of the modality of mechanical ventilation on bleeding during pituitary surgery: A single blinded randomized trial

BACKGROUND

Bleeding modifies the surgeon's view of the field during transsphenoidal endoscopic pituitary surgery. Since ventilation can alter venous return, we compared the effect of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on intraoperative bleeding.

METHODS

Eighty-six patients were randomized to VCV or PCV in this single blinded study; comparisons concerned 42 in the PCV group and 43 in the VCV group.

RESULTS

Intraoperative bleeding, the primary endpoint, did not differ between groups whether analysis focused on 7 levels of the score, from minimal bleeding to bleeding with significant change in the conduct of surgical procedure (P = .89) or on a stratification into 3 categories, mild, moderate, and major (P = .47). Median [interquartile range] peak airway pressure was lower in the PCV group (13.5 [12.5-15] vs 16.3 [14.4-19.1] cm H2O, P < .001) while mean airway pressures were similar (P = .08). Means ± SD of tidal volumes were lower in the VCV group when expressed as absolute values (470.6 ± 84 vs 434.7 ± 71.7 ml, P = .05) or as tidal volume/theoretical ideal weight ratio (6.7 [6.5-7] vs 7.2 [6.9-7.9], P < .001). The 2 groups were similar for postoperative complications and number of patients cured.

CONCLUSION

In conclusion, ventilation mode does not influence intraoperative bleeding during transsphenoidal pituitary surgery.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01891838; July 3, 2013.

Effect of prolonged inspiratory time on gas exchange during robot-assisted laparoscopic urologic surgery

BACKGROUND

Gas exchange disturbance may develop during urologic robotic laparoscopic surgery with the patient in a steep Trendelenburg position. This study investigated whether prolonged inspiratory time could mitigate gas exchange disturbances including hypercapnia.

METHODS

In this randomized cross-over trial, 32 patients scheduled for robot-assisted urologic surgery were randomized to receive an inspiratory to expiratory time ratio (I:E) of 1:1 for the first hour of pneumoperitoneum followed by 1:2 for last period of surgery (group A, n = 17) or I:E of 1:2 followed by 1:1 (group B, n = 15). Arterial blood gas analysis, airway pressure and hemodynamic variables were assessed at four time points (T1: 10 min after induction of general anesthesia, T2: 1 h after the initiation of pneumoperitoneum, T3: 1 h after T2 and T4: at skin closure). The carry over effect of initial I:E was also evaluated over the next hour through arterial blood gas analysis.

RESULTS

There was a significant decrease in partial pressure of oxygen in arterial blood (PaO₂) for both groups at T2 and T3 compared to T1 but in group B the PaO₂ at T4 was not decreased from the baseline. Partial pressure of carbon dioxide in arterial blood (PaCO₂) increased with I:E of 1:2 but did not significantly increase with I:E of 1:1; however, there were no differences in PaO₂ and PaCO₂ between the groups.

CONCLUSION

Decreased oxygenation by pneumoperitoneum was improved and PaCO₂ did not increase after 1 h of I:E of 1:1; however, the effect of equal ratio ventilation longer than 1 h remains to be determined. There was no carryover effect of the two different I:E ratios.

The association of postoperative pulmonary complications in 109,360 patients with pressure-controlled or volume-controlled ventilation

We thought that the rate of postoperative pulmonary complications might be higher after pressure-controlled ventilation than after volume-controlled ventilation. We analysed peri-operative data recorded for 109,360 adults, whose lungs were mechanically ventilated during surgery at three hospitals in Massachusetts, USA. We used multivariable regression and propensity score matching. Postoperative pulmonary complications were more common after pressure-controlled ventilation, odds ratio (95%CI) 1.29 (1.21-1.37), p < 0.001. Tidal volumes and driving pressures were more varied with pressure-controlled ventilation compared with volume-controlled ventilation: mean (SD) variance from the median 1.61 (1.36) ml.kg^-1 vs. 1.23 (1.11) ml.kg^-1 , p < 0.001; and 3.91 (3.47) cmH₂ O vs. 3.40 (2.69) cmH₂ O, p < 0.001. The odds ratio (95%CI) of pulmonary complications after pressure-controlled ventilation compared with volume-controlled ventilation at positive end-expiratory pressures < 5 cmH₂ O was 1.40 (1.26-1.55) and 1.20 (1.11-1.31) when ≥ 5 cmH₂ O, both p < 0.001, a relative risk ratio of 1.17 (1.03-1.33), p = 0.023. The odds ratio (95%CI) of pulmonary complications after pressure-controlled ventilation compared with volume-controlled ventilation at driving pressures of < 19 cmH₂ O was 1.37 (1.27-1.48), p < 0.001, and 1.16 (1.04-1.30) when ≥ 19 cmH₂ O, p = 0.011, a relative risk ratio of 1.18 (1.07-1.30), p = 0.016. Our data support volume-controlled ventilation during surgery, particularly for patients more likely to suffer postoperative pulmonary complications.

Intraoperative low tidal volume ventilation strategy has no benefits during laparoscopic cholecystectomy

Background and Aims:

Benefits of intraoperative low tidal volume ventilation during laparoscopic surgery are not conclusively proven, even though its advantages were seen in other situations with intraoperative respiratory compromise such as one-lung ventilation. The present study compared the efficacy of intraoperative low tidal volume ventilatory strategy (6 ml/kg along with positive end-expiratory pressure [PEEP] of 10 cmH₂O) versus one with higher tidal volume (10 ml/kg with no PEEP) on various clinical parameters and plasma levels of interleukin (IL)-6 in patients undergoing laparoscopic cholecystectomy.

Material and Methods:

A total of 58 adult patients with American Society of Anesthesiologists physical status I or II, undergoing laparoscopic cholecystectomy were randomized to receive the low or higher tidal volume strategy as above (n = 29 each). The primary outcome measure was postoperative PaO₂. Systemic levels of IL-6 along with clinical indices of intraoperative gas exchange, pulmonary mechanics, and hemodynamic consequences were measured as secondary outcome measures.

Results:

There was no statistically significant difference in oxygenation; intraoperative dynamic compliance, peak airway pressures, or hemodynamic parameters, or the IL-6 levels between the two groups (P > 0.05). Low tidal volume strategy was associated with significantly higher mean airway pressure, lower airway resistance, greater respiratory rates, and albeit clinically similar, higher PaCO₂and lower pH (P < 0.05).

Conclusion:

Strategy using 6 ml/kg tidal volume along with 10 cmH₂O of PEEP was not associated with any significant improvement in gas exchange, hemodynamic parameters, or systemic inflammatory response over ventilation with 10 ml/kg volume without PEEP during laparoscopic cholecystectomy.

Comparison of volume controlled ventilation and pressure controlled ventilation in patients undergoing robot-assisted pelvic surgeries: An open-label trial

Background and Aims:

Although volume controlled ventilation (VCV) has been the traditional mode of ventilation in robotic surgery, recently pressure controlled ventilation (PCV) has been used more frequently. However, evidence on whether PCV is superior to VCV is still lacking. We intended to compare the effects of VCV and PCV on respiratory mechanics and haemodynamic in patients undergoing robotic surgeries in steep Trendelenburg position.

Methods:

This prospective, randomized trial was conducted on sixty patients between 20 and 70 years belonging to the American Society of Anesthesiologist Physical Status I–II. Patients were randomly assigned to VCV group (n = 30), where VCV mode was maintained through anaesthesia, or the PCV group (n = 30), where ventilation mode was changed to PCV after the establishment of 40° Trendelenburg position and pneumoperitoneum. Respiratory (peak and mean airway pressure [AP_peak, AP_mean], dynamic lung compliance [C_dyn] and arterial blood gas analysis) and haemodynamics variables (heart rate, mean blood pressure [MBP] central venous pressure) were measured at baseline (T₁), post-Trendelenburg position at 60 min (T₂), 120 min (T₃) and after resuming supine position (T₄).

Results:

Demographic profile, haemodynamic variables, oxygen saturation and minute ventilation (MV) were comparable between two groups. Despite similar values of AP_mean, AP_peak was significantly higher in VCV group at T2 and T3 as compared to PCV group (P < 0.001). C_dyn and PaCO₂ were also better in PCV group than in VCV group (P < 0.001 and 0.045, respectively).

Conclusion:

PCV should be preferred in robotic pelvic surgeries as it offers lower airway pressures, greater C_dyn and a better-preserved ventilation-perfusion matching for the same levels of MV.

Features of respiratory support during laparoscopic correction of inguinal hernias in children

INTRODUCTION

The objectives were to study the changes in the mechanics of respiration in children undergoing surgery depending on the value of intra-abdominal pressure (IAP) during laparoscopic procedures, and to compare the effects of different mechanical ventilation modes - pressure controlled (PCV) and volume controlled (VCV) ventilation - on the mechanics of respiration considering carboxyperitoneum conditions (CP).

AIM

To study the changes in the mechanics of respiration in operated children depending on the value of intra-abdominal pressure during laparoscopic procedures.

MATERIAL AND METHODS

Fifty-two children aged 1-12 years undergoing laparoscopic surgery on inguinal hernias were randomly allocated to receive mechanical ventilation using either VCV (n = 24) or PCV (n = 28) mode. Respiratory mechanics were measured before application of carboxyperitoneum (initial data) and after the gas had been pumped into the abdominal cavity, at the following intra-abdominal pressure values: 6 mm Hg, 8 mm Hg, 10 mm Hg, 12 mm Hg, 14 mm Hg.

RESULTS

Elevation of intra-abdominal pressure due to carboxyperitoneum conditions had a negative effect on the mechanics of respiration. Changes in the respiratory mechanics were restrictive in nature in both groups. The patients who were receiving pressure controlled ventilation showed a decrease in tidal volume, exhaled minute volume, and dynamic lung compliance, which affected the gas exchange at intra-abdominal pressure values ≥ 12 mm Hg. Patients who were receiving volume controlled ventilation showed an increase in peak inspiratory pressure and mean airway pressure and a decrease in dynamic lung compliance in response to higher intra-abdominal pressure. A significant increase of concentration of exhaled carbon dioxide (etCO2) was registered at IAP ≥ 12 mm Hg.

CONCLUSIONS

Application of carboxyperitoneum causes increased intra-abdominal pressure and restrictive disorders in respiratory mechanics. Intra-abdominal pressure readings within 8-12 mm Hg allow laparoscopic procedures to be performed without significant gas exchange disorders in children older than 1 year.

Effects of pressure-controlled and volume-controlled ventilation on respiratory mechanics and systemic stress response during laparoscopic cholecystectomy

Pressure-controlled ventilation (PCV) is less frequently employed in general anesthesia. With its high and decelerating inspiratory flow, PCV has faster tidal volume delivery and different gas distribution. The same tidal volume setting, delivered by PCV versus volume-controlled ventilation (VCV), will result in a lower peak airway pressure and reduced risk of barotrauma. We hypothesized that PCV instead of VCV during laparoscopic surgery could achieve lower airway pressures and reduce the systemic stress response. Forty ASA I-II patients were randomly selected to receive either the PCV (Group PC, n = 20) or VCV (Group VC, n = 20) during laparoscopic cholecystectomy. Blood sampling was made for baseline arterial blood gases (ABG), cortisol, insulin, and glucose levels. General anesthesia with sevoflurane and fentanyl was employed to all patients. After anesthesia induction and endotracheal intubation, patients in Group PC were given pressure support to form 8 mL/kg tidal volume and patients in Group VC was maintained at 8 mL/kg tidal volume calculated using predicted body weight. All patients were maintained with 5 cmH₂O positive-end expiratory pressure (PEEP). Respiratory parameters were recorded before and 30 min after pneumoperitonium. Assessment of ABG and sampling for cortisol, insulin and glucose levels were repeated 30 min after pneumoperitonium and 60 min after extubation. The P-peak levels observed before (18.9 ± 3.8 versus 15 ± 2.2 cmH₂O) and during (23.3 ± 3.8 versus 20.1 ± 2.9 cmH₂O) pneumoperitoneum in Group VC were significantly higher. Postoperative partial arterial oxygen pressure (PaO₂) values are higher (98 ± 12 versus 86 ± 11 mmHg) in Group PC. Arterial carbon dioxide pressure (PaCO₂) values (41.8 ± 5.4 versus 36.7 ± 3.5 mmHg) during pneumoperitonium and post-operative mean cortisol and insulin levels were higher in Group VC. When compared to VCV mode, PCV mode may improve compliance during pneumoperitoneum, improve oxygenation and reduce stress response postoperatively and may be more appropriate in patients having laparoscopic surgery.

The Effects of Volume-Controlled and Pressure-Controlled Ventilation on Lung Mechanics, Oxidative Stress, and Recovery in Gynecologic Laparoscopic Surgery

STUDY OBJECTIVE

To compare ventilation variables, changes in oxidative stress, and the quality of recovery in 2 different ventilation strategies (volume-controlled ventilation [VCV] and pressure-controlled ventilation [PCV]) during gynecologic laparoscopic surgery.

DESIGN

A prospective randomized controlled trial (Canadian Task Force classification I).

SETTING

One university teaching hospital in Taiwan.

PATIENTS

Women scheduled for laparoscopic gynecologic surgery.

INTERVENTIONS

Women were randomly assigned to receive either VCV or PCV during surgery.

MEASUREMENTS AND MAIN RESULTS

Ventilation variables were recorded 1 minute before and 1 hour after pneumoperitoneum. Blood samples were collected for malondialdehyde measurement at 7 points: 1 minute before and 1 hour after pneumoperitoneum; 30, 60, 90, and 120 minutes after deflation; and 24 hours after surgery. Postoperative recovery was assessed by using a 9-item quality of recovery score at 24 hours after surgery. A total of 52 women randomly allocated to the VCV (n = 27) or PCV (n = 25) group completed the study. We found that after 1 hour of insufflation the PCV group had lower peak airway pressure (22.0 ± 3.4 vs 26.6 ± 4.1 cm H2O, p < .0001) and higher compliance (28.4 ± 3.7 vs 24.1 ± 3.3 mL/cm H2O, p < .0001) than the VCV group. In plasma levels of malondialdehyde, there were no significant differences between the 2 groups at 7 time points. The levels significantly increased in both groups after 1 hour of pneumoperitoneum and peaked at 2 hours after deflation. During postoperative recovery, lower scores were obtained at 24 hours after surgery compared with preoperative scores, but there were no significant differences between the 2 groups.

CONCLUSION

PCV is an alternative ventilation mode in gynecologic laparoscopic surgery. However, PCV offered lower peak airway pressure and higher compliance than VCV but no advantages over VCV in oxidative stress or quality of recovery.

Hemodynamic Effects of Volume-Controlled Ventilation Versus Pressure-Controlled Ventilation in Head Trauma Patients

Background. Controlled ventilation for head trauma patients should reduce hypoxemia, hypercapnia and prevent secondary brain injury. However, changes in cardiac output and arterial blood pressure are the common consequences of mechanical ventilation. This study was designed to compare pressure- versus volume-controlled ventilation modes in severe head trauma patients to identify the mode with least hemodynamic compromise and best oxygenation profile. Methods. This prospective crossover study was carried out on 15 severe head trauma patients admitted to surgical ICU for mechanical ventilation and critical care. All patients were initially ventilated with volume-controlled ventilation for 12 hours then the mode of ventilation was changed to pressure-controlled ventilation for the next 12 hours. Arterial and pulmonary artery catheters were inserted for continuous monitoring of arterial blood pressure, cardiac output, pulmonary artery pressure, pulmonary wedge pressure, pulmonary vascular resistance, and systemic vascular resistance every 4 hours from the start of each ventilation mode. Lung mechanics and arterial blood gases were simultaneously recorded during the times of hemodynamic monitoring. Results. Cardiac output did not show significant changes between the 2 ventilation modes and mean group differences at 4, 8, and 12 hours were −0.2, −0.2, −0.1 L/min (95% confidence interval = −1.04 to 0.64, −0.92 to 0.52, and −0.68 to 0.48 L/min), respectively. Additionally, the other hemodynamic variables were comparable at all levels of study analysis. Volume-controlled ventilation was associated with significant higher peak air way pressure in comparison with pressure-controlled ventilation after 4, 8, and 12 hours. The oxygenation values and other lung mechanics were not significantly change between the 2 ventilation modes. Conclusion. Both volume-controlled and pressure-controlled ventilations have comparable hemodynamic and oxygenation profiles in severe head trauma patients for short-term ventilation.