Adaptive support ventilation for gynaecological laparoscopic surgery in Trendelenburg position: bringing ICU modes of mechanical ventilation to the operating room

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.

Obesity in laparoscopic surgery

Since the 1980s, minimally invasive techniques have been applied to an increasing number and variety of surgical procedures with a gradual increase in the complexity of procedures being successfully performed laparoscopically. In the past, obesity was considered a contraindication to laparoscopy due to the higher risk of co-morbid conditions such as diabetes, hypertension, coronary artery disease and venous thromboembolism. Performing laparoscopic gynaecological procedures in morbidly obese patients is no longer a rare phenomenon; however, it does necessitate changes in clinical practice patterns. Understanding of the physiological changes induced by laparoscopy, particularly in obese patients, is important so that these may be counteracted and adverse outcomes avoided. Laparoscopy in obese patients confers certain advantages such as shorter hospital stay, less post-operative pain and fewer wound infections. In addition to these benefits, minimal-access surgery has been demonstrated as safe and effective in obese patients; however, specific surgical strategies and operative techniques may need to be adopted.

Pressure-controlled inverse ratio ventilation using laryngeal mask airway in gynecological laparoscopy

BACKGROUND

It is well documented that pressure-controlled ventilation (PCV) improves oxygenation and ventilation compared to volume-controlled ventilation and reduces peak airway pressure in gynecological laparoscopy. PCV with moderately inversed inspiratory-expiratory (I: E) ratio can successfully recruit collapsed alveoli and has been proved to be beneficial in intensive care. We tested the hypothesis that altering the I: E ratio to 1.5:1 in PCV improves ventilation during gynecological laparoscopy using laryngeal mask airway (LMA).

OBJECTIVE

To study pressure-controlled inverse ratio ventilation (PCIRV) with I: E ratio 1.5:1 as against PCV with I: E ratio 1:2 in gynecological laparoscopy with LMA using noninvasive parameters.

MATERIALS AND METHODS

Intraoperative hemodynamics and side-stream spirometry recordings were noted in 20 consecutive patients undergoing major gynecological laparoscopy with LMA. Flexible LMA or LMA supreme were used depending on normal body mass index (BMI) or high BMI, respectively.

RESULTS

REVERSING THE I: E ratio to 1.5:1 increased the tidal volume, mean airway pressures, and dynamic lung compliance significantly, all indicating better oxygenation at comparable peak airway pressures as against PCV with I: E ratio 1:2. There was no change in the end-tidal carbon dioxide. There was no auto-positive end expiratory pressure (PEEP) or change in the hemodynamics.

CONCLUSION

REVERSAL OF I: E ratio with PCV can be beneficially used with LMA in laparoscopy.

Management of mechanical ventilation during laparoscopic surgery

Laparoscopy is widely used in the surgical treatment of a number of diseases. Its advantages are generally believed to lie on its minimal invasiveness, better cosmetic outcome and shorter length of hospital stay based on surgical expertise and state-of-the-art equipment. Thousands of laparoscopic surgical procedures performed safely prove that mechanical ventilation during anaesthesia for laparoscopy is well tolerated by a vast majority of patients. However, the effects of pneumoperitoneum are particularly relevant to patients with underlying lung disease as well as to the increasing number of patients with higher-than-normal body mass index. Moreover, many surgical procedures are significantly longer in duration when performed with laparoscopic techniques. Taken together, these factors impose special care for the management of mechanical ventilation during laparoscopic surgery. The purpose of the review is to summarise the consequences of pneumoperitoneum on the standard monitoring of mechanical ventilation during anaesthesia and to discuss the rationale of using a protective ventilation strategy during laparoscopic surgery. The consequences of chest wall derangement occurring during pneumoperitoneum on airway pressure and central venous pressure, together with the role of end-tidal-CO2 monitoring are emphasised. Ventilatory and non-ventilatory strategies to protect the lung are discussed.

Pressure-controlled vs volume-controlled ventilation during laparoscopic gynecologic surgery

STUDY OBJECTIVE

To quantify and compare the effects of conventional volume-controlled ventilation (VCV) with the alternative mode, pressure-controlled ventilation (PCV), on respiratory mechanics and noninvasive hemodynamic parameters in patients undergoing laparoscopic gynecologic surgery.

DESIGN

Randomized controlled trial (Canadian Task Force classification I).

SETTING

Respiratory mechanics and hemodynamic parameters were recorded for each patient at time T1, 10 minutes after induction, in the supine position; T2, 15 minutes after pneumoperitoneum, in the Trendelenburg position; and T3, 10 minutes after pneumoperitoneum withdrawal, in the supine position.

PATIENTS

Sixty women, aged 20 to 50 years, undergoing laparoscopic gynecologic surgery, with American Society of Anesthesiologists classes I and II disease.

INTERVENTIONS

Patients were randomly allocated to 1 of 2 groups. In the VCV group (n = 30), ventilation mode was maintained, whereas in the PCV group (n = 30), ventilation mode was changed to PVC.

MEASUREMENTS AND MAIN RESULTS

Both groups were comparable insofar as patient characteristics, operating time, pneumoperitoneum time, anesthesia time, and mean operative time. VCV was associated with a significant increase in peak airway pressure, plateau pressure, and airway resistance at T2 (p < .05). Compliance was significantly higher in the PCV group at T2 (p < .05). No other statistically significant differences were found between the groups.

CONCLUSIONS

Both VCV and PCV seem to be equally suited for use in patients undergoing laparoscopic gynecologic surgery. However, lower peak airway pressure, plateau pressure, and airway resistance, and higher compliance are observed with PCV in laparoscopic gynecologic surgery.