Volume-controlled versus pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation

Comparison of pressure controlled, volume controlled, and volume guaranteed pressure controlled modes in prone position in patients operated for lumbar disc herniation: A randomized trial

BACKGROUND

To compare pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), and pressure-controlled ventilation-volume guaranteed (PCV-VG) modes in patients undergoing spinal surgery in the prone position under general anesthesia.

METHODS

The study included 78 patients aged 20 to 80 years, American Society of Anesthesiologists 1-2, scheduled for lumbar spinal surgery. Patients included in the study were randomly divided into 3 groups Group-VCV; Group-PCV; Group-PCV-VG. Standard anesthesia protocol was applied. In addition to routine monitoring, train of four and BIS monitoring were performed. All ventilation modes were set with a target tidal volume of 6 to 8 mL/kg, FiO2: 0.40-0.45 and a respiratory rate of normocarbia. Positive end-expiratory pressure: 5 cm H2O, inspiration/expiration ratio = 1:2, and the maximum airway pressure:40 cm H2O. Hemodynamic, respiratory variables and arterial blood gases was measured, 15 minutes after induction of anesthesia in the supine position (T1), after prone position 15 minutes (T2), 30 minutes (T3), 45 minutes (T4), 60 minutes (T5), 75 minutes (T6), 90 minutes (T7).

RESULTS

There was no significant difference between the groups in patient characteristics. SAP, DAP, mean arterial pressure, and heart rate decreased after being placed in the prone position in all groups. Hemodynamic variables did not differ significantly between the groups. partial arterial oxygen pressure and arterial oxygen saturation levels in blood gas were found to be significantly higher in Group-PCV-VG compared to Group-PCV and Group-VCV in both the supine and prone positions. Ppeak and plateau airway pressure (Pplato) values increased and dynamic lung compliance (Cdyn) values decreased after placing the patients in the prone position in all groups. Lower Ppeak and Pplato values and higher Cdyn values were observed in both the supine and prone positions in the Group-PCV-VG group compared to the Group-PCV and Group-VCV groups.

CONCLUSION

PCV-VG provides lower Ppeak and Pplato values, as well as better Cdyn, oxygenation values compared to PCV and VCV. So that PCV-VG may be an effective alternative mode of mechanical ventilation for patients in the prone position during lumbar spine surgery.

Pressure-controlled ventilation-volume guaranteed mode improves bronchial mucus transport velocity in patients during laparoscopic surgery for gynecological oncology: a randomized controlled study

BACKGROUND

Mechanical ventilation during general anesthesia may impair airway mucosal function. This study aimed to investigate the effect of pressure-controlled ventilation-volume guaranteed (PCV-VG) on bronchial mucus transport velocity (BTV) in patients during laparoscopic surgery for gynecological oncology compared with volume controlled ventilation (VCV).

METHODS

66 patients undergoing elective a laparoscopic surgery for gynecological oncology. The patients were randomized into two group receiving either PCV-VG or VCV. a drop of methylene blue was placed on the surface of the airway mucosa under the bronchoscopeand, then the distance the dye movement was measured after 2, 4, and 6 min. Outcomes were assessed at T0 (5 min after endotracheal intubation and before initiation of pneumoperitoneum), T1 and T2 (1 and 2 h after stabilization of pneumoperitoneum respectively). BTV at T0, T1 and T2 was the primary outcome. Secondary outcomes included heart rate (HR), mean arterial pressure (MAP), body temperature, end-tidal CO2 pressure (PETCO2), tidal volume(VT), peak inspiratory pressure (PIP), mean inspiratory pressure (Pmean), respiratory rate (RR), and dynamic compliance (CDyn) at T0, T1, and T2.

RESULTS

64 patients were included in the analysis. The median [interquartile range] BTV was significantly lower in VCV group at T1 and T2 that at T0 (P < 0.05). Furthermore, BTV was slightly reduced in PCV-VG compared with VCV. BTV in PCV-VG was significantly decreased at T2 compared with BTV at T0 (P < 0.05) and slightly decreased at T1 compared with T0(P > 0.05). Compared with the PCV-VG group, BTV in VCV group significantly decreased at T2 (P < 0.05). No participants experienced respiratory complications.

CONCLUSIONS

PCV-VG is more suitable for patients undergoing laparoscopic surgery for gynecological oncology than VCV since it can protect mucociliary clearance function.

TRIAL REGISTRATION

This trial is registered on https://www.chictr.org.cn/ in Chinese Clinical Trial Registry (ChiCTR.2200064564: Date of registration 11/10/2022).

Evaluation of the Effect of Pressure-Controlled Ventilation-Volume Guaranteed Mode vs. Volume-Controlled Ventilation Mode on Atelectasis in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Clinical Trial

Background and Objectives: Laparoscopic surgery, which results in less bleeding, less postoperative pain, and better cosmetic results, may affect the lung dynamics via the pneumoperitoneum. After laparoscopic surgery, atelectasis develops. The primary aim of the present study is to demonstrate the effects of two different ventilation modes on the development of atelectasis using lung ultrasound, and the secondary outcomes include the plateau pressure, peak inspiratory pressure, and compliance differences between the groups. Materials and Methods: In this study, 62 participants aged 18-75 years undergoing laparoscopic cholecystectomy were enrolled. The patients were randomly assigned into two groups: the volume-controlled ventilation (VCV) group (group V) or the pressure-controlled-volume guaranteed ventilation (PCV-VG) group (group PV). The lung ultrasound score (LUS) was obtained thrice: prior to induction (T1), upon the patient's initial arrival in the recovery room (T2), and just before departing the recovery unit (T3). The hemodynamic data and mechanical ventilation parameters were recorded at different times intraoperatively. Results: The LUS score was similar between the groups at all the times. The change in the LUS score of the right lower anterior chest was statistically higher in the VCV group than the PCV group. The peak inspiratory pressure (PIP) was found to be statistically higher in the V group than the PV group five minutes after induction (T5) (20.84 ± 4.32 p = 0.021). The plateau pressure was found to be higher in the V group than the PV group at all times (after induction (Tind) 17.29 ± 5.53 p = 0.004, (T5) 17.77 ± 4.89 p = 0.001, after pneumoperitoneum (TPP) 19.71 ± 4.28 p = 0.002). Compliance was found to be statistically higher in the PV group than the V group at all times ((Tind) 48.87 ± 15.37 p = 0.011, (T5) 47.94 ± 13.71 p = 0.043, (TPP) 35.65 ± 6.90 p = 0.004). Before and after the pneumoperitoneum, the compliance was determined to be lower in the V group than the PV group, respectively (40.68 ± 13.91 p = 0.043, 30.77 ± 5.73 p = 0.004). Conclusions: LUS score was similar between groups at all times. The PCV-VG mode was superior to the VCV mode in providing optimal ventilatory pressures and maintaining high dynamic compliance in patients undergoing laparoscopic abdominal surgery.

Effect of permissive hypercarbia on lung oxygenation during one-lung ventilation and postoperative pulmonary complications in patients undergoing thoracic surgery: A prospective randomised controlled trial

BACKGROUND

The effect of hypercarbia on lung oxygenation during thoracic surgery remains unclear.

OBJECTIVE

To investigate the effect of hypercarbia on lung oxygenation during one-lung ventilation in patients undergoing thoracic surgery and evaluate the incidence of postoperative pulmonary complications.

DESIGN

Prospective randomised controlled trial.

SETTING

A tertiary university hospital in the Republic of Korea from November 2019 to December 2020.

PATIENTS

Two hundred and ninety-seven patients with American Society of Anaesthesiologists physical status II to III, scheduled to undergo elective lung resection surgery.

INTERVENTION

Patients were randomly assigned to Group 40, 50, or 60. An autoflow ventilation mode with a lung protective ventilation strategy was applied to all patients. Respiratory rate was adjusted to maintain a partial pressure of arterial carbon dioxide of 40 ± 5 mmHg in Group 40, 50 ± 5 mmHg in Group 50 and 60 ± 5 mmHg in Group 60 during one-lung ventilation and at the end of surgery.

MAIN OUTCOME MEASURES

The primary outcome was the arterial oxygen partial pressure/fractional inspired oxygen ratio after 60 min of one-lung ventilation.

RESULTS

Data from 262 patients were analysed. The partial pressure/fractional inspired oxygen ratio was significantly higher in Group 50 and Group 60 than in Group 40 (269.4 vs. 262.9 vs. 214.4; P  < 0.001) but was not significantly different between Group 50 and Group 60. The incidence of postoperative pulmonary complications was comparable among the three groups.

CONCLUSION

Permissive hypercarbia improved lung oxygenation during one-lung ventilation without increasing the risk of postoperative pulmonary complications or the length of hospital stay.

TRIAL REGISTRATION

NCT04175379.

Pressure-Controlled Volume-Guaranteed Ventilation Improves Respiratory Dynamics in Pediatric Patients During Laparoscopic Surgery: A Prospective Randomized Controlled Trial

Purpose

Pressure-controlled volume-guaranteed (PCV-VG) combines the characteristics of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV). It has been reported that PCV-VG decreases airway pressure and improves oxygenation among the adult group. In this study, the respiratory dynamics of PCV-VG and VCV are compared in pediatric patients ventilated with laryngeal mask airway and underwent laparoscopic hernia of the sac ligation.

Patients and Methods

Sixty-four pediatric patients were included in this prospective, randomized clinical trial. Pediatric patients were randomly allocated to receive VCV and PCV-VG ventilation during the general anesthesia. The hemodynamic and respiratory variables were recorded at the time when laryngeal mask airway was placed, pneumoperitoneum began, 5 mins after pneumoperitoneum began, pneumoperitoneum ended, and the operation ended respectively. The respiratory adverse events were recorded after the operation and on the first day after the operation. In this study, respiratory adverse events are defined as cough, hoarseness, hypoxemia, laryngospasm, bronchospasm, and sore throat.

Results

There was no statistical difference in hemodynamic variables at all time points between the two groups. Compared to the VCV group, peak airway pressure (Ppeak) and plateau airway pressure in the PCV-VG group decreased significantly. Pulmonary dynamic compliance (Cydn) in the PCV-VG group was significantly higher than that in the VCV group. The respiratory adverse events appeared to have no statistical difference between VCV and PCV groups.

Conclusion

PCV-VG provides a lower Ppeak and better Cydn in pediatric patients compared with the VCV group during laparoscopic surgery. The results suggested that PCV-VG may be a superior way of mechanical ventilation for pediatric patients who ventilated with laryngeal mask airway and experienced laparoscopic surgery.

Comparison of Volume-Guaranteed or -Targeted, Pressure-Controlled Ventilation with Volume-Controlled Ventilation during Elective Surgery: A Systematic Review and Meta-Analysis

For perioperative mechanical ventilation under general anesthesia, modern respirators aim at combining the benefits of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in modes typically named “volume-guaranteed” or “volume-targeted” pressure-controlled ventilation (PCV-VG). This systematic review and meta-analysis tested the hypothesis that PCV-VG modes of ventilation could be beneficial in terms of improved airway pressures (P_peak, P_plateau, P_mean), dynamic compliance (C_dyn), or arterial blood gases (P_aO₂, P_aCO₂) in adults undergoing elective surgery under general anesthesia. Three major medical electronic databases were searched with predefined search strategies and publications were systematically evaluated according to the Cochrane Review Methods. Continuous variables were tested for mean differences using the inverse variance method and 95% confidence intervals (CI) were calculated. Based on the assumption that intervention effects across studies were not identical, a random effects model was chosen. Assessment for heterogeneity was performed with the χ² test and the I² statistic. As primary endpoints, P_peak, P_plateau, P_mean, C_dyn, P_aO₂, and P_aCO₂ were evaluated. Of the 725 publications identified, 17 finally met eligibility criteria, with a total of 929 patients recruited. Under supine two-lung ventilation, PCV-VG resulted in significantly reduced P_peak (15 studies) and P_plateau (9 studies) as well as higher C_dyn (9 studies), compared with VCV [random effects models; P_peak: CI −3.26 to −1.47; p < 0.001; I² = 82%; P_plateau: −3.12 to −0.12; p = 0.03; I² = 90%; C_dyn: CI 3.42 to 8.65; p < 0.001; I² = 90%]. For one-lung ventilation (8 studies), PCV-VG allowed for significantly lower P_peak and higher P_aO₂ compared with VCV. In Trendelenburg position (5 studies), this effect was significant for P_peak only. This systematic review and meta-analysis demonstrates that volume-targeting, pressure-controlled ventilation modes may provide benefits with respect to the improved airway dynamics in two- and one-lung ventilation, and improved oxygenation in one-lung ventilation in adults undergoing elective surgery.

A nationwide survey of intraoperative management for one-lung ventilation in Taiwan: time to accountable for diversity in protective lung ventilation

BACKGROUND

There is a major paradigm shift for intraoperative mechanical ventilator support by the introduction of lung protective ventilation strategies to reduce postoperative pulmonary complications and improve overall clinical outcomes in non-thoracic surgeries. However, there is currently a lack of standardized practice guideline for lung protection during thoracic surgeries that require one-lung ventilation (OLV). This study aimed to collect the expert opinions of the thoracic anesthesiologists in perioperative care for OLV surgery in Taiwan.

METHODS

This prospective cross-sectional study was undertaken in 16 tertiary hospitals in Taiwan from January to February 2019. A structured survey form was distributed across the participating hospitals and the thoracic anesthesiologists were invited to complete the form voluntarily. The survey form consisted of three parts, including the basic information of the institutional anesthesia care standards, ventilatory settings for a proposed patient receiving OLV surgery and expert opinions on OLV.

RESULTS

A total of 71 thoracic anesthesiologists responded to the survey. Double-lumen tubes are the most commonly used (93.8%) airway devices for OLV. The most commonly recommended ventilator setting during OLV is a tidal volume of 6-7 ml/kg PBW (67.6%) and a PEEP level of 4-6 cmH₂O (73.5%). Dual controlled ventilator modes are used by 44.1% of the anesthesiologists. During OLV, high oxygen fraction (FiO₂ > 0.8) is more commonly supplemented to achieve an oxygen saturation higher than 94%. The consensus of anesthesiologists on the indices for lung protection in thoracic surgery is considerably low. Large majority of the anesthesiologists (91.5%) highly recommend that an international clinical practice guideline on the protective lung ventilation strategy for thoracic anesthesia should be established.

CONCLUSIONS

This study found that the thoracic anesthesiologists in Taiwan share certain common practices in ventilator support during OLV. However, they are concerned about the lack of fundamental clinical evidences to support the beneficial outcomes of the current lung protective strategies applicable to OLV. Large-scale trials are needed to form an evidence-based clinical practice guideline for thoracic anesthesia.

Comparison between volume-controlled ventilation and pressure-controlled volume-guaranteed ventilation in postoperative lung atelectasis using lung ultrasound following upper abdominal laparotomies: a prospective randomized study

Background

Atelectasis is a common side effect of general anesthesia. Prevention of lung atelectasis, carbon dioxide retention, and chest infection would improve the quality of medical care and decrease hospital stay and costs. The aim of this study was to compare the effects of volume-controlled ventilation (VCV) and pressure-controlled volume-guaranteed ventilation (PCVG) on postoperative lung atelectasis using lung ultrasound (LUS) following upper abdominal laparotomies.

Results

Sixty patients (male and female) scheduled for upper abdominal laparotomies. They were randomly allocated into two equal groups: Group A (n = 30): received intraoperative volume-controlled ventilation (VCV) mode and group (n = 30): received intraoperative pressure-controlled ventilation volume-guaranteed (PCV-VG) mode. Arterial blood samples were obtained immediately after extubation, and 30, 120, 240, and 360 min postextubation. Lung ultrasound was done intraoperatively at 30 min from induction, immediate, and 120 and after 360 min postoperatively. There was difference between two groups favoring PCV-VG group but that difference failed to be statically significant regarding arterial partial pressure of oxygen (PaO₂) and arterial carbon dioxide tension (PaCo₂) between the two groups in preoperative, immediate postoperative, and 120, 240, and 360 min postoperative. Arterial oxygen saturation (SaO₂) was significantly lower among patients in the VCV group immediate postextubation compared with patients in group PCV-VG (p value = 0.009*). Although signs of atelectasis were low in group B, 36.7% of the patients showed normal lung ultrasound, 63.3% showed various abnormalities, 46.7% showed the presence of lung pulse (vertical rhythmic movement synchronous with cardiac pulsation through motionless lung), and 46.7% showed B lines (vertical lines indicate abnormal lung aeration), while 30% of the patients showed the absence of A-lines (indicates the absence of lung sliding and abnormal lung aeration). Also, some patients demonstrated more than one sign. However, there was no a significant difference between the two groups both showed atelectasis immediate, 2 h and 6 h postoperatively.

Conclusion

PCV-VG offered no significant advantage over VCV regarding the occurrence of the postoperative atelectasis. However, we prefer to use PCV-VG as postoperative hypoxia and atelectasis was much less in that mode. Further, large-scale studies are required to confirm these findings and to establish a definite conclusion.

Pressure-Controlled Ventilation-Volume Guaranteed Mode Combined with an Open-Lung Approach Improves Lung Mechanics, Oxygenation Parameters, and the Inflammatory Response during One-Lung Ventilation: A Randomized Controlled Trial

We evaluated the effectiveness of pressure-controlled ventilation-volume guaranteed (PCV-VG) mode combined with open-lung approach (OLA) in patients during one-lung ventilation (OLV). First, 176 patients undergoing thoracoscopic surgery were allocated randomly to four groups: PCV+OLA (45 cases, PCV-VG mode plus OLA involving application of individualized positive end-expiratory pressure (PEEP) after a recruitment maneuver), PCV (44 cases, PCV-VG mode plus standard lung-protective ventilation with fixed PEEP of 5 cmH₂O), VCV+OLA (45 cases, volume-controlled ventilation (VCV) plus OLA), and VCV (42 cases, VCV plus standard lung-protective ventilation). Mean airway pressure (P_mean), dynamic compliance (Cdyn), PaO₂/FiO₂ ratio, intrapulmonary shunt ratio (Qs/Qt), dead space fraction (V_D/V_T), and plasma concentration of neutrophil elastase were obtained to assess the effects of four lung-protective ventilation strategies. At 45 min after OLV, the median (interquartile range (IQR)) P_mean was higher in the PCV+OLA group (13.00 (12.00, 13.00) cmH₂O) and the VCV+OLA group (12.00 (12.00, 14.00) cmH₂O) than in the PCV group (11.00 (10.00, 12.00) cmH₂O) and the VCV group (11.00 (10.00, 12.00) cmH₂O) (P < 0.05); the median (IQR) Cdyn was higher in the PCV+OLA group (27.00 (24.00, 32.00) mL/cmH₂O) and the VCV+OLA group (27.00 (22.00, 30.00) mL/cmH₂O) than in the PCV group (23.00 (21.00, 25.00) mL/cmH₂O) and the VCV group (20.00 (18.75, 21.00) mL/cmH₂O) (P < 0.05); the median (IQR) Qs/Qt in the PCV+OLA group (0.17 (0.16, 0.19)) was significantly lower than that in the PCV group (0.19 (0.18, 0.20)) and the VCV group (0.19 (0.17, 0.20)) (P < 0.05); V_D/V_T was lower in the PCV+OLA group (0.18 ± 0.05) and the VCV+OLA group (0.19 ± 0.07) than in the PCV group (0.21 ± 0.07) and the VCV group (0.22 ± 0.06) (P < 0.05). The concentration of neutrophil elastase was lower in the PCV+OLA group than in the PCV, VCV+OLA, and VCV groups at total-lung ventilation 10 min after OLV (162.47 ± 25.71, 198.58 ± 41.99, 200.84 ± 22.17, and 286.95 ± 21.10 ng/mL, resp.) (P < 0.05). In conclusion, PCV-VG mode combined with an OLA strategy leads to favorable effects upon lung mechanics, oxygenation parameters, and the inflammatory response during OLV.

Effect of Pressure-Controlled Ventilation-Volume Guaranteed on One-Lung Ventilation in Elderly Patients Undergoing Thoracotomy

Background

Volume-controlled ventilation (VCV) in one-lung ventilation (OLV) is most commonly used in thoracotomy, but pressure-controlled ventilation-volume guaranteed (PCV-VG) is used in elderly patients to improve arterial oxygenation, reduce inflammatory factors, and decrease acute lung injury (ALI). The purpose of this study was to investigate the effects of these 2 different ventilation modes – VCV versus PCV-VG – during OLV in elderly patients undergoing thoracoscopic lobectomy.

Material/Methods

Sixty patients undergoing thoracoscopic lobectomy from September 2018 to February 2019 at Cangzhou Central Hospital, Hebei, China were randomly assigned to a VCV group or a PCV-VG group. Pulmonary dynamic compliance (Cdyn), peak inspiratory pressure (PIP), arterial blood gas, and inflammatory factors were monitored to assess lung function. The Clinical Trial Registration Identifier number is ChiCTR1800017835.

Results

Compared with the VCV group, PIP in the PCV-VG group was significantly lower (P=0.01) and Cdyn was significantly higher at 30 min after one-lung ventilation (P=0.01). MAP of the PCV-VG group was higher than in the VCV group (P=0.01). MAP of the PCV-VG group was also higher than in the VCV group at 30 min after one-lung ventilation (P=0.01). The concentration of neutrophil elastase (NE) in the PCV-VG group was significantly lower than in the VCV group (P=0.01).

Conclusions

Compared with VCV, PCV-VG mode reduced airway pressure in patients undergoing thoracotomy and also decreased the release of NE and reduced inflammatory response and lung injury. We conclude that PCV-VG mode can protect the lung function of elderly patients undergoing thoracotomy.

Comparison of volume-controlled, pressure-controlled, and pressure-controlled volume-guaranteed ventilation during robot-assisted laparoscopic gynecologic surgery in the Trendelenburg position

Background: Pressure-controlled ventilation volume-guaranteed (PCV-VG) is being increasingly used for ventilation during general anesthesia. Carbon dioxide (CO₂) pneumoperitoneum in the Trendelenburg position is routinely used during robot-assisted laparoscopic gynecologic surgery. Here, we hypothesized that PCV-VG would reduce peak inspiratory pressure (Ppeak), compared to volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Methods: In total, 60 patients were enrolled in this study and randomly assigned to receive VCV, PCV, or PCV-VG. Hemodynamic variables, respiratory variables, and arterial blood gases were measured in the supine position 15 minutes after the induction of anesthesia (T0), 30 and 60 minutes after CO₂ pneumoperitoneum and Trendelenburg positioning (T1 and T2, respectively), and 15 minutes after placement in the supine position at the end of anesthesia (T3). Results: The Ppeak was higher in the VCV group than in the PCV and PCV-VG groups (p=0.011). Mean inspiratory pressure (Pmean) was higher in the PCV and PCV-VG groups than in the VCV group (p<0.001). Dynamic lung compliance (Cdyn) was lower in the VCV group than in the PCV and PCV-VG groups (p=0.001). Conclusion: Compared to VCV, PCV and PCV-VG provided lower Ppeak, higher Pmean, and improved Cdyn, without significant differences in hemodynamic variables or arterial blood gas results during robot-assisted laparoscopic gynecologic surgery with Trendelenburg position.

Comparison of pressure-controlled volume-guaranteed ventilation and volume-controlled ventilation in obese patients during gynecologic laparoscopic surgery in the Trendelenburg position

Background and objectives

The aim of this study was to investigate the efficacy of the pressure-controlled, volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) modes for maintaining adequate airway pressures, lung compliance and oxygenation in obese patients undergoing laparoscopic hysterectomy in the Trendelenburg position.

Methods

Patients (104) who underwent laparoscopic gynecologic surgery with a body mass index between 30 and 40 kg.m⁻² were randomized to receive either VCV or PCV-VG ventilation. The tidal volume was set at 8 mL.kg⁻¹, with an inspired oxygen concentration of 0.4 with a Positive End-Expiratory Pressure (PEEP) of 5 mmHg. The peak inspiratory pressure, mean inspiratory pressure, plateau pressure, driving pressure, dynamic compliance, respiratory rate, exhaled tidal volume, etCO₂, arterial blood gas analysis, heart rate and mean arterial pressure at 5 minutes after induction of anesthesia in the and at 5, 30 and 60 minutes, respectively, after pneumoperitoneum in the Trendelenburg position were recorded.

Results

The PCV-VG group had significantly decreased peak inspiratory pressure, mean inspiratory pressur, plateau pressure, driving pressure and increased dynamic compliance compared to the VCV group. Mean PaO₂ levels were significantly higher in the PCV-VG group than in the VCV group at every time point after pneumoperitoneum in the Trendelenburg position.

Conclusions

The PCV-VG mode of ventilation limited the peak inspiratory pressure, decreased the driving pressure and increased the dynamic compliance compared to VCV in obese patients undergoing laparoscopic hysterectomy. PCV-VG may be a preferable modality to prevent barotrauma during laparoscopic surgeries in obese patients.

Effects of small tidal volume and positive end-expiratory pressure on oxygenation in pressure-controlled ventilation-volume guaranteed mode during one-lung ventilation

Background

The purpose of this study was to investigate whether tidal volume (TV) of 8 mL/kg without positive end-expiratory pressure (PEEP) and TV of 6 mL/kg with or without PEEP in pressure-controlled ventilation-volume guaranteed (PCV-VG) mode can maintain arterial oxygenation and decrease inspiratory airway pressure effectively during one-lung ventilation (OLV).

Methods

The study enrolled 27 patients undergoing thoracic surgery. All patients were ventilated with PCV-VG mode. During OLV, patients were initially ventilated with TV 8 mL/kg (group TV8) without PEEP. Ventilation was subsequently changed to TV 6 mL/kg with PEEP (5 cmH₂O; group TV6+PEEP) or without (group TV6) in random sequence. Peak inspiratory pressure (P_peak), mean airway pressure (P_mean), and arterial blood gas analysis were measured 30 min after changing ventilator settings. Ventilation was then changed once more to add or eliminate PEEP (5 cmH₂O), while maintaining TV 6 mL/kg. Thirty min after changing ventilator settings, the same parameters were measured once more.

Results

The P_peak was significantly lower in group TV6 (19.3±3.3 cmH₂O) than in group TV8 (21.8±3.1 cmH₂O) and group TV6+PEEP (20.1±3.4 cmH₂O). PaO₂ was significantly higher in group TV8 (242.5±111.4 mmHg) than in group TV6 (202.1±101.3 mmHg) (p=0.044). There was no significant difference in PaO₂ between group TV8 and group TV6+PEEP (226.8±121.1 mmHg). However, three patients in group TV6 were dropped from the study because PaO₂ was lower than 80 mmHg after ventilation.

Conclusion

It is postulated that TV 8 mL/kg without PEEP or TV 6 mL/kg with 5 cmH₂O PEEP in PCV-VG mode during OLV can safely maintain adequate oxygenation.

Comparison of volume-controlled ventilation mode and pressure-controlled ventilation with volume-guaranteed mode in the prone position during lumbar spine surgery

Background

During lumbar spine surgery, patients are placed in the prone position for surgical access. The prone position has various effects on cardiac and pulmonary function, including a decreased cardiac index (CI), decreased dynamic lung compliance (Cdyn), and increased peak inspiratory pressure (Ppeak). In this study, we compared the volume-controlled ventilation mode (VCV) and pressure-controlled ventilation with volume guaranteed mode (PCV-VG) based on hemodynamic and pulmonary variables in the prone position during lumbar spine surgery.

Methods

Thirty-six patients scheduled for lumbar spine surgery in the prone position were enrolled in this prospective, randomized clinical trial. The patients were randomly assigned to receive VCV or PCV-VG. Hemodynamic variables, respiratory variables, and arterial blood gases were measured in the supine position 15 min after the induction of anesthesia, 15 min after placement in the prone position, 30 min after placement in the prone position, and 15 min after placement in the supine position at the end of anesthesia.

Results

The hemodynamic variables and arterial blood gas results did not differ significantly between the two groups. Lower Ppeak values were observed in the PCV-VG group than in the VCV group (p = 0.045). The Cdyn values in the VCV group were lower than those in the PCV-VG group (p = 0.040).

Conclusion

PCV-VG led to lower Ppeak and improved Cdyn values compared with VCV, showing that it may be a favorable alternative mode of mechanical ventilation for patients in the prone position during lumbar spine surgery.

Trial registration

The study was retrospectively registered at ClinicalTrials.gov (NCT 03571854). The initial registration date was 6/18/2018.

Pressure-Controlled Ventilation with Volume Guarantee Compared to Volume-Controlled Ventilation with Equal Ratio in Obese Patients Undergoing Laparoscopic Hysterectomy

Background:

Laparoscopic hysterectomy operations especially for obese patients necessitate Trendelenburg position and pneumoperitoneum with carbon dioxide, which could affect cardiac and pulmonary functions. The present study aimed to compare the impact of pressure-controlled ventilation with volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) with equal ratio ventilation (ERV), i.e., I: E ratio of 1:1 on hemodynamics, respiratory mechanics, and oxygenation.

Patients and Methods:

Eighty females with body mass index (BMI) >30 kg/m² and with physical status American Society of Anesthesiologists Classes I and II undergoing laparoscopic hysterectomy were allocated randomly to either PCV-VG (Group P) or VCV with ERV (Group V). The ventilation parameters, hemodynamics, and arterial blood gases (ABGs) analysis were recorded at four times: (T₁): after the anesthetic induction while in supine position by 10 min, (T₂ and T₃): after the CO2 pneumoperitoneum and Trendelenburg positioning by 30 and 60 min, respectively, and (T₄): after desufflation and resuming the supine position.

Results:

The peak inspiratory pressure in Group P recorded significant lower values than in Group V while the dynamic compliance was greater significantly in Group P than in Group V. No significant differences were reported as regards the ABG analysis, oxygenation, and hemodynamic data between both groups.

Conclusion:

In obese females undergoing laparoscopic hysterectomy surgeries, PCV-VG was superior to VCV with ERV as it provided higher dynamic compliance and lower peak inspiratory pressure that could be preferable, especially in those patients in whom cardiopulmonary function could be more susceptible to impairment.

Comparisons of Pressure-controlled Ventilation with Volume Guarantee and Volume-controlled 1:1 Equal Ratio Ventilation on Oxygenation and Respiratory Mechanics during Robot-assisted Laparoscopic Radical Prostatectomy: a Randomized-controlled Trial

Background: During robot-assisted laparoscopic radical prostatectomy (RALP), steep Trendelenburg position and carbon dioxide pneumoperitoneum are inevitable for surgical exposure, both of which can impair cardiopulmonary function. This study was aimed to compare the effects of pressure-controlled ventilation with volume guarantee (PCV with VG) and 1:1 equal ratio ventilation (ERV) on oxygenation, respiratory mechanics and hemodynamics during RALP. Methods: Eighty patients scheduled for RALP were randomly allocated to either the PCV with VG or ERV group. After anesthesia induction, volume-controlled ventilation (VCV) was applied with an inspiratory to expiratory (I/E) ratio of 1:2. Immediately after pneumoperitoneum and Trendelenburg positioning, VCV with I/E ratio of 1:1 (ERV group) or PCV with VG using Autoflow mode (PCV with VG group) was initiated. At the end of Trendelenburg position, VCV with I/E ratio of 1:2 was resumed. Analysis of arterial blood gases, respiratory mechanics, and hemodynamics were compared between groups at four times: 10 min after anesthesia induction (T1), 30 and 60 min after pneumoperitoneum and Trendelenburg positioning (T2 and T3), and 10 min after desufflation and resuming the supine position (T4). Results: There were no significant differences in arterial blood gas analyses including arterial oxygen tension (PaO₂) between groups throughout the study period. Mean airway pressure (Pmean) were significantly higher in the ERV group than in the PCV with VG group T2 (p<0.001) and T3 (p=0.002). Peak airway pressure and hemodynamic data were comparable in both groups. Conclusion: PCV with VG was an acceptable alternative to ERV during RALP producing similar PaO₂ values. The lower Pmean with PCV with VG suggests that it may be preferable in patients with reduced cardiovascular function.

Pressure-controlled Volume Guaranteed Mode Improves Respiratory Dynamics during Laparoscopic Cholecystectomy: A Comparison with Conventional Modes

Background:

Pneumoperitoneum and altered positioning 1in laparoscopic cholecystectomy predispose to alterations in cardiorespiratory physiology. We compared the effects of volume controlled, pressure controlled, and the newly introduced pressure controlled-volume guaranteed ventilation (PCV-VG) modes of ventilation on respiratory mechanics and oxygenation during laparoscopic cholecystectomy.

Materials and Methods:

Seventy-five physical status American Society of Anesthesiologists Classes I and II patients with normal lungs undergoing laparoscopic cholecystectomy were randomly allocated to receive volume controlled ventilation (VCV), pressure-controlled ventilation (PCV), or PCV-VG modes of ventilation during general anesthesia. In all modes of ventilation, the tidal volume was set at 8 mL/kg, and respiratory rate was set at 12 breaths/min with inspired oxygen of 0.4. After pneumoperitoneum, respiratory rate was adjusted to maintain an end-tidal carbon dioxide between 32 and 37 mm Hg. The peak airway pressures, compliance, the mean airway pressures, oxygen saturation, end tidal carbon dioxide and hemodynamics were recorded at the time of intubation (T1), 15 min after pneumoperitoneum (T2) and after desufflation (T3) and were compared. Arterial oxygen tension, arterial carbon dioxide tension at T2 and T3 were compared.

Results:

PCV-VG and PCV mode resulted in lower peak airway pressures than VCV (23.04 ± 3.43, 24.52 ± 2.79, and 27.24 ± 2.37 cm of water, respectively, P = 0.001). Compliance was better preserved in the pressure mediated modes than VCV (fall from baseline was 42%, 29%, and 30% in VCV, PCV, and PCV-VG). The arterial to end-tidal carbon dioxide gradient was lower in PCV-VG and PCV compared to VCV. No difference in oxygenation and hemodynamics were observed.

Conclusion:

PCV and PCV-VG modes are superior to VCV mode in providing adequate oxygenation at lower peak inspiratory pressures.

The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy

Patients undergoing lobectomy are at significantly increased risk of lung injury. One-lung ventilation is the most commonly used technique to maintain ventilation and oxygenation during the operation. It is a challenge to choose an appropriate mechanical ventilation strategy to minimize the lung injury and other adverse clinical outcomes. In order to understand the available evidence, a systematic review was conducted including the following topics: (I) protective ventilation (PV); (II) mode of mechanical ventilation [e.g., volume controlled (VCV) versus pressure controlled (PCV)]; (III) use of therapeutic hypercapnia; (IV) use of alveolar recruitment (open-lung) strategy; (V) pre-and post-operative application of positive end expiratory pressure (PEEP); (VI) Inspired Oxygen concentration; (VII) Non-intubated thoracoscopic lobectomy; and (VIII) adjuvant pharmacologic options. The recommendations of class II are non-intubated thoracoscopic lobectomy may be an alternative to conventional one-lung ventilation in selected patients. The recommendations of class IIa are: (I) Therapeutic hypercapnia to maintain a partial pressure of carbon dioxide at 50-70 mmHg is reasonable for patients undergoing pulmonary lobectomy with one-lung ventilation; (II) PV with a tidal volume of 6 mL/kg and PEEP of 5 cmH₂O are reasonable methods, based on current evidence; (III) alveolar recruitment [open lung ventilation (OLV)] may be beneficial in patients undergoing lobectomy with one-lung ventilation; (IV) PCV is recommended over VCV for patients undergoing lung resection; (V) pre- and post-operative CPAP can improve short-term oxygenation in patients undergoing lobectomy with one-lung ventilation; (VI) controlled mechanical ventilation with I:E ratio of 1:1 is reasonable in patients undergoing one-lung ventilation; (VII) use of lowest inspired oxygen concentration to maintain satisfactory arterial oxygen saturation is reasonable based on physiologic principles; (VIII) Adjuvant drugs such as nebulized budesonide, intravenous sivelestat and ulinastatin are reasonable and can be used to attenuate inflammatory response.

Pressure-controlled versus volume-controlled ventilation during one-lung ventilation for video-assisted thoracoscopic lobectomy

BACKGROUND

It is controversial as to which ventilation mode is better during one-lung ventilation (OLV). This study was designed to figure out whether there was any difference between volume controlled ventilation (VCV) and pressure controlled ventilation (PCV) on oxygenation and postoperative complications under the condition of protective ventilation (PV).

METHODS

Sixty-five patients undergoing video-assisted thoracoscopic lobectomy were randomized into two groups. Patients in group V received VCV mode during OLV while patients in group P received PCV. The tidal volume (VT) in both groups was 6 mL per predicted body weight (PBW). Positive end-expiratory pressure (PEEP) was set at the level of 5 cmH₂O in both groups. Arterial gas analysis were performed preoperatively with room air (T₀), at 15 mins (T₁) and 1 h (T₂) after OLV, at the end of OLV (T₃), 30 min after PACU admission (T₄), 24 h after surgery (post-operative day 1, POD₁) and 48 h after surgery (post-operative day 2, POD₂). Peak inspiratory airway pressure (Ppeak) and plateau airway pressure (Pplat) were recorded at T₁, T₂ and T₃. The perioperative complications were also recorded.

RESULT

Sixty-four patients completed this study. Ppeak in group V was significantly higher than that in group P (T₁ 22.3±2.9 vs. 18.7±2.1 cmH₂O; T₂ 22.2±2.8 vs. 18.7±2.6 cmH₂O). There were no differences with Pplat and intraoperative oxygenation index (T₁ 203.3±109.7 vs. 198.1±93.4; T₂ 216.8±79.1 vs. 232.1±101.4). The postoperative oxygenation index (T₄ 525.0±160.9 vs. 520.7±127.1, post-operative day 1 (POD₁) 452.1±161.3 vs. 446.1±109.1; post-operative day 2 (POD₂) 403.8±93.4 vs. 396.7±92.8) and postoperative complications were also comparable between these two groups.

CONCLUSIONS

When they were utilized during OLV, PCV and VCV had the same performance on the intraoperative oxygenation and postoperative complications under the condition of PV.

Intraoperative mechanical ventilation strategies in patients undergoing one-lung ventilation: a meta-analysis

BACKGROUND

Postoperative pulmonary complications (PPCs), which are not uncommon in one-lung ventilation, are among the main causes of postoperative death after lung surgery. Intra-operative ventilation strategies can influence the incidence of PPCs. High tidal volume (V T) and increased airway pressure may lead to lung injury, while pressure-controlled ventilation and lung-protective strategies with low V T may have protective effects against lung injury. In this meta-analysis, we aim to investigate the effects of different ventilation strategies, including pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), protective ventilation (PV) and conventional ventilation (CV), on PPCs in patients undergoing one-lung ventilation. We hypothesize that both PV with low V T and PCV have protective effects against PPCs in one-lung ventilation.

METHODS

A systematic search (PubMed, EMBASE, the Cochrane Library, and Ovid MEDLINE; in May 2015) was performed for randomized trials comparing PCV with VCV or comparing PV with CV in one-lung ventilation. Methodological quality was evaluated using the Cochrane tool for risk. The primary outcome was the incidence of PPCs. The secondary outcomes included the length of hospital stay, intraoperative plateau airway pressure (Pplateau), oxygen index (PaO2/FiO2) and mean arterial pressure (MAP).

RESULTS

In this meta-analysis, 11 studies (436 patients) comparing PCV with VCV and 11 studies (657 patients) comparing PV with CV were included. Compared to CV, PV decreased the incidence of PPCs (OR 0.29; 95 % CI 0.15-0.57; P < 0.01) and intraoperative Pplateau (MD -3.75; 95 % CI -5.74 to -1.76; P < 0.01) but had no significant influence on the length of hospital stay or MAP. Compared to VCV, PCV decreased intraoperative Pplateau (MD -1.46; 95 % CI -2.54 to -0.34; P = 0.01) but had no significant influence on PPCs, PaO2/FiO2 or MAP.

CONCLUSIONS

PV with low V T was associated with the reduced incidence of PPCs compared to CV. However, PCV and VCV had similar effects on the incidence of PPCs.

Comparison of three ventilatory modes during one-lung ventilation in elderly patients

OBJECTIVE

The purpose of this study was to explore the effects of three different ventilatory modes: volume controlled ventilation (VCV), pressure controlled ventilation (PCV) and pressure controlled ventilation-volume guaranteed (PCV-VG) on arterial oxygenation and airway pressure during one-lung ventilation (OLV) in elderly patients.

METHODS

We enrolled 66 patients who underwent thoracic surgery requiring at least 1 hour of OLV and aged above 65 years into the study. Patients were classified into VCV, PCV and PCV-VG groups according to a controlled, randomized design. Patients were ventilated to obtain a tidal volume (TV) of 8 mL/kg with three different ventilatory modes during OLV. The Hemodynamic and respiratory data had been recorded during intraoperation and arterial blood gases were obtained at baseline, 20, 40, 60 minutes after OLV, end of surgery.

RESULTS

Compared with VCV group, Ppeak was significantly lower in PCV and PCV-VG group (P<0.05), and the difference was not found between the PCV and PCV-VG group. PaO2 in PCV and PCV-VG group were higher than VCV group after the point of OLV+40 (P<0.05). Comparison of PCV group, PaO2 in PCV-VG group was higher, but did not show a significantly improved during OLV (P>0.05).

CONCLUSIONS

Compared with VCV, the use of PCV and PCV-VG have a significant advantage in intraoperative oxygenation and airway pressure for eldly patients undergoing OLV.