A comparison between volume-controlled ventilation and pressure-controlled ventilation in providing better oxygenation in obese patients undergoing laparoscopic cholecystectomy

Volume-controlled ventilation versus pressure-controlled ventilation during spine surgery in the prone position: A meta-analysis

Background

Many studies have investigated a comparison of the potency and safety of PCV versus VCV modes in spinal surgery in prone position. However, controversy about the maximal benefits of which ventilation modes remains. The main purpose of this meta-analysis was to investigate which one is the optimal ventilation for surgery patients undergoing spine surgery in prone position between the two ventilation modes as PCV and VCV.

Methods

We conducted a comprehensive search of PubMed, Embase, Web of Science, the Cochrane Library, and Google Scholar for potentially eligible articles. The continuous outcomes were analyzed using the mean difference and the associated 95% confidence interval. Meta-analysis was performed using Review Manager 5.4 software.

Results

Our meta-analysis included 8 RCTs involving a total of 454 patients between 2012 and 2020. The results demonstrated that IOB, Ppeak and CVP for VCV are significantly superior to PCV in spinal surgery in prone position. And PCV had higher Cdyn and PaO₂/FiO₂ than VCV. But there was no significant difference between PCV and VCV in terms of POB, Hb, HCT, HR and MAP.

Conclusions

The PCV mode displayed a more satisfying effect than VCV mode. Compared to VCV mode in same preset of tidal volume, the patients with PCV mode in prone position demonstrated less IOB, lower Ppeak and CVP, and higher PaO₂/FiO₂ in spinal surgery. However, there is no obvious difference between PCV and VCV in terms of hemodynamics variables (HR and MAP).

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The PCV mode displayed a more satisfying effect than VCV mode.

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Compared to VCV mode, the patients with PCV mode in prone position demonstrated less IOB, lower Ppeak and CVP, and higher PaO2/FiO2 in spinal surgery.

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There is no obvious difference between PCV and VCV in terms of hemodynamics variables.

Comparison of Pressure and Volume-Controlled Mechanical Ventilation in Laparoscopic Bariatric Surgery: A Randomized Crossover Trial

Background

The number of patients with obesity undergoing various surgeries is increasing annually, and ventilation problems are highly prevalent in these patients.

Objectives

We aimed to evaluate ventilation effectiveness with pressure-controlled (PC) and volume-controlled (VC) ventilation modes during laparoscopic bariatric surgery.

Methods

In this open-label randomized crossover clinical trial, 40 adult patients with morbid obesity candidates for laparoscopic bariatric surgery were assigned to VC-PC or PC-VC groups. Each patient received both ventilation modes sequentially for 15 min during laparoscopic surgery in a random sequence. Every 5 min, exhaled tidal volume, peak and mean airway pressure, oxygen saturation, heart rate, mean arterial pressure, and end-tidal CO₂ were recorded. Blood gas analysis was done at the end of 15 min. Dynamic compliance, PaO₂/FiO₂ ratio, P (A-a) O₂ gradient, respiratory dead space, and PaCO₂-ETCO₂ gradient were calculated according to the obtained results.

Results

The study included 40 patients with a mean age of 35.13 ± 9.06 years. There were no significant differences in peak and mean airway pressure, dynamic compliance, and hemodynamic parameters (P > 0.05). There was no significant difference between the two ventilation modes in pH, PaCO₂, PaO₂, PaO₂/FIO₂, dead space volume, and D (A-a) O₂ at different time intervals (P > 0.05).

Conclusions

If low tidal volumes are used during adult laparoscopic bariatric surgery, mechanical ventilation with PC mode is not superior to VC mode.

Abstract No.: ABS0586: Is pressure control ventilation better than volume control in patients undergoing spine surgery in prone position?

Background & Aims:

Optimisation of intraoperative ventilation is feasible nowadays due to availability of several new modes in anaesthesia workstations. Spine surgery in prone position leads to pulmonary and haemodynamic alterations. The present study aimed to compare PCV and VCV modes of ventilation in patients undergoing spine surgeries.

Methods:

After obtaining approval from institutional ethics committee the present, prospective, randomised study was conducted in 50 adult patient of either sex, ASA I or II undergoing thoracic or lumbar spine surgery in prone position. Standard anaesthesia protocols using Thiopentone, Fentanyl and Vecuroniun was followed. Patients in VCV group (n=25) were ventilated with volume control mode with TV = 7 ml/kg, PEEP=5cm H2O, I: E=1:2 and respiratory rate adjusted to keep Et CO2 between 35-40 mmHg and FiO2 =0.4. While in PCV mode (n=25) patients were ventilated with similar settings except PIP was adjusted to determine TV=7ml/kg. Draeger Primus workstation was used.

Results:

Demographic profile, duration of surgery, intraoperative dry and fluid consumption were comparable in two groups. Peak inspiratory pressure was higher in VCV (20 vs 18) and dynamics compliance was low in VCV (31.3 vs 35.93). Minute ventilation, EtCO2, dead space, O2 saturation was comparable in two groups though alveolar oxygenation was better in PCV. Diastolicblood pressure was low in VCV. Postoperative PFT decreased in both groups but were comparable.

Conclusion:

PCV is better than VCV in maintaining intraoperative respiratory mechanisms but whether they offer long term benefit require more studies comprising of larger sample sizes.

Effects of intraoperative inverse ratio ventilation on postoperative pulmonary function tests in the patients undergoing laparoscopic cholecystectomy: A prospective single blind study

Background and Aims:

Induction of general anaesthesia is associated with development of atelectasis in the lungs, which may further lead to postoperative pulmonary complications. Inverse ratio ventilation (IRV) has shown to improve oxygenation and minimise further lung injury in patients with acute respiratory distress syndrome. We evaluated the safety and effectiveness of IRV on intraoperative respiratory mechanics and postoperative pulmonary function tests (PFTs).

Methods:

In a prospective, controlled study, 128 consecutive patients with normal preoperative PFTs who underwent elective laparoscopic cholecystectomy were randomised into IRV and conventional ventilation groups. Initially, all patients were ventilated with settings of tidal volume 8 mL/kg, respiratory rate 12/min, inspiratory/expiratory ratio (I: E) = 1:2, positive end expiratory pressure = 0. Once the pneumoperitoneum was created, the conventional group patients were continued to be ventilated with same settings. However, in the IRV group, I: E ratio was changed to 2:1. Peak pressure (Ppeak), Plateau pressure (Pplat) and lung compliance were measured. Haemodynamic parameters and arterial blood gas values were also measured. PFTs were repeated in postoperative period. Statistical tool included Chi-square test.

Results:

There was no significant difference in PFTs in patients who underwent IRV as compared to conventional ventilation [forced vital capacity (FVC) 2.52 ± 0.13 versus 2.63 ± 0.16, P = 0.28]. The Ppeak (cmH2O) and Pplat (cmH2O) were statistically lower in IRV patients [Ppeak 21.4 ± 3.4 versus 22.4 ± 4.2, P = 0.003] [Pplat 18.7 ± 2.4 versus 19.9.4 ± 3.2, P = 0.008]. There was no significant difference in lung compliance and oxygenation intraoperatively.

Conclusion:

Intraoperative IRV led to reduced airway pressures; however, it did not prevent deterioration of PFTs in postoperative period.

[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.

Perioperative lung protective ventilation

Perioperative lung injury is a major source of postoperative morbidity, excess healthcare use, and avoidable mortality. Many potential inciting factors can lead to this condition, including intraoperative ventilator induced lung injury. Questions exist as to whether protective ventilation strategies used in the intensive care unit for patients with acute respiratory distress syndrome are equally beneficial for surgical patients, most of whom do not present with any pre-existing lung pathology. Studied both individually and in combination as a package of intraoperative lung protective ventilation, the use of low tidal volumes, moderate positive end expiratory pressure, and recruitment maneuvers have been shown to improve oxygenation and pulmonary physiology and to reduce postoperative pulmonary complications in at risk patient groups. Further work is needed to define the potential contributions of alternative ventilator strategies, limiting excessive intraoperative oxygen supplementation, use of non-invasive techniques in the postoperative period, and personalized mechanical ventilation. Although the weight of evidence strongly suggests a role for lung protective ventilation in moderate risk patient groups, definitive evidence of its benefit for the general surgical population does not exist. However, given the shift in understanding of what is needed for adequate oxygenation and ventilation under anesthesia, the largely historical arguments against the use of intraoperative lung protective ventilation may soon be outdated, on the basis of its expanding track record of safety and efficacy in multiple settings.

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 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.

Controlled invasive mechanical ventilation strategies in obese patients undergoing surgery

INTRODUCTION

The obesity prevalence is increasing in surgical population. As the number of obese surgical patients increases, so does the demand for mechanical ventilation. Nevertheless, ventilatory strategies in this population are challenging, since obesity results in pathophysiological changes in respiratory function. Areas covered: We reviewed the impact of obesity on respiratory system and the effects of controlled invasive mechanical ventilation strategies in obese patients undergoing surgery. To date, there is no consensus regarding the optimal invasive mechanical ventilation strategy for obese surgical patients, and no evidence that possible intraoperative beneficial effects on oxygenation and mechanics translate into better postoperative pulmonary function or improved outcomes. Expert commentary: Before determining the ideal intraoperative ventilation strategy, it is important to analyze the pathophysiology and comorbidities of each obese patient. Protective ventilation with low tidal volume, driving pressure, energy, and mechanical power should be employed during surgery; however, further studies are required to clarify the most effective ventilation strategies, such as the optimal positive end-expiratory pressure and whether recruitment maneuvers minimize lung injury. In this context, an ongoing trial of intraoperative ventilation in obese patients (PROBESE) should help determine the mechanical ventilation strategy that best improves clinical outcome in patients with body mass index≥35kg/m².

Comparison of volume control and pressure control ventilation in patients undergoing single level anterior cervical discectomy and fusion surgery

Background and Aims:

Pressure control and volume control ventilation are the most preferred modes of ventilator techniques available in the intraoperative period. The study compared the intraoperative ventilator and blood gas variables of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) in patients undergoing single level anterior cervical discectomy and fusion (ACDF).

Methods:

After obtaining Institutional Ethical Committee approval and informed consent, sixty patients scheduled for single level ACDF surgery performed in supine position under general anaesthesia were included. Group V (30 patients) received VCV and Group P (30 patients) received PCV. The primary objective was oxygenation variable PaO₂/FiO₂ at different points of time i.e. T1–20 min after the institution of the ventilation, T2–20 min after placement of the retractors and T3–20 min after removal of the retractors. The secondary objectives include other arterial blood gas parameters, respiratory and haemodynamic parameters. NCSS version 9 statistical software was used for statistics. Two-way repeated measures for analysis of variance with post hoc Tukey Kramer test was used to analyse continuous variables for both intra- and inter-group comparisons, paired sample t-test for overall comparison and Chi-square test for categorical data.

Results:

The primary variable PaO₂/FiO₂ was comparable in both groups (P = 0.08). The respiratory variables, PAP and C_dynam were statistically significant in PCV group compared to VCV (P < 0.05), though clinically insignificant. Other secondary variables were comparable. (P > 0.05)

Conclusion:

Clinically, both PCV and VCV group appear to be-equally suited ventilator techniques for anterior cervical spine surgery patients.

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.

Preoxygenation and intraoperative ventilation strategies in obese patients: a comprehensive review

PURPOSE OF REVIEW

Obesity along with its pathophysiological changes increases risk of intraoperative and perioperative respiratory complications. The aim of this review is to highlight recent updates in preoxygenation techniques and intraoperative ventilation strategies in obese patients to optimize gas exchange and pulmonary mechanics and reduce pulmonary complications.

RECENT FINDINGS

There is no gold standard in preoxygenation or intraoperative ventilatory management protocol for obese patients. Preoxygenation in head up or sitting position has been shown to be superior to supine position. Apneic oxygenation and use of continuous positive airway pressure increases safe apnea duration. Recent evidence encourages the intraoperative use of low tidal volume to improve oxygenation and lung compliance without adverse effects. Contrary to nonobese patients, some studies have reported the beneficial effect of recruitment maneuvers and positive end-expiratory pressure in obese patients. No difference has been observed between volume controlled and pressure controlled ventilation.

SUMMARY

The ideal ventilatory plan for obese patients is indeterminate. A multimodal preoxygenation and intraoperative ventilation plan is helpful in obese patients to reduce perioperative respiratory complications. More studies are needed to identify the role of low tidal volume, positive end-expiratory pressure, and recruitment maneuvers in obese patients undergoing general anesthesia.

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.

Brazilian recommendations of mechanical ventilation 2013. Part 2

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumologia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

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.

Brazilian recommendations of mechanical ventilation 2013. Part 2

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumologia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.