Changes in lung and chest wall properties with abdominal insufflation of carbon dioxide are immediately reversible

Benefits of intratracheal and extrathoracic high-frequency percussive ventilation in a model of capnoperitoneum

Abdominal inflation with CO2 is used to facilitate laparoscopic surgeries, however, providing adequate mechanical ventilation in this scenario is of major importance during anesthesia management. We characterized high-frequency percussive ventilation (HFPV) in protecting from the gas exchange and respiratory mechanical impairments during capnoperitoneum. In addition, we aimed to assess the difference between conventional pressure-controlled mechanical ventilation (CMV) and HFPV modalities generating the high-frequency signal intratracheally (HFPVi) or extrathoracally (HFPVe). Anesthetized rabbits (n = 16) were mechanically ventilated by random sequences of CMV, HFPVi, and HFPVe. The ventilator superimposed the conventional waveform with two high-frequency signals (5 Hz and 10 Hz) during intratracheal HFPV (HFPVi) and HFPV with extrathoracic application of oscillatory signals through a sealed chest cuirass (HFPVe). Lung oxygenation index ([Formula: see text]/[Formula: see text]), arterial partial pressure of carbon dioxide ([Formula: see text]), intrapulmonary shunt (Qs/Qt), and respiratory mechanics were assessed before abdominal inflation, during capnoperitoneum, and after abdominal deflation. Compared with CMV, HFPVi with additional 5-Hz oscillations during capnoperitoneum resulted in higher [Formula: see text]/[Formula: see text], lower [Formula: see text], and decreased Qs/Qt. These improvements were smaller but remained significant during HFPVi with 10 Hz and HFPVe with either 5 or 10 Hz. The ventilation modes did not protect against capnoperitoneum-induced deteriorations in respiratory tissue mechanics. These findings suggest that high-frequency oscillations combined with conventional pressure-controlled ventilation improved lung oxygenation and CO2 removal in a model of capnoperitoneum. Compared with extrathoracic pressure oscillations, intratracheal generation of oscillatory pressure bursts appeared more effective. These findings may contribute to the optimization of mechanical ventilation during laparoscopic surgery.NEW & NOTEWORTHY The present study examines an alternative and innovative mechanical ventilation modality in improving oxygen delivery, CO2 clearance, and respiratory mechanical abnormalities in a clinically relevant experimental model of capnoperitoneum. Our data reveal that high-frequency oscillations combined with conventional ventilation improve gas exchange, with intratracheal oscillations being more effective than extrathoracic oscillations in this clinically relevant translational model.

Impact of a positive end-expiratory pressure strategy on oxygenation, respiratory compliance, and hemodynamics during laparoscopic surgery in non-obese patients: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Higher positive end-expiratory pressure (PEEP) during laparoscopic surgery may increase oxygenation and respiratory compliance. This meta-analysis aimed to compare the impact of different intraoperative PEEP strategies on arterial oxygenation, compliance, and hemodynamics during laparoscopic surgery in non-obese patients.

METHODS

We searched RCTs in PubMed, Cochrane Library, Web of Science, and Google Scholar from January 2012 to April 2022 comparing the different intraoperative PEEP (Low PEEP (LPEEP): 0-4 mbar; Moderate PEEP (MPEEP): 5-8 mbar; high PEEP (HPEEP): >8 mbar; individualized PEEP - iPEEP) on arterial oxygenation, respiratory compliance (Cdyn), mean arterial pressure (MAP), and heart rate (HR). We calculated mean differences (MD) with 95% confidence intervals (CI), and predictive intervals (PI) using random-effects models. The Cochrane Bias Risk Assessment Tool was applied.

RESULTS

21 RCTs (n = 1554) met the inclusion criteria. HPEEP vs. LPEEP increased PaO2 (+ 29.38 [16.20; 42.56] mmHg, p < 0.0001) or PaO2/FiO2 (+ 36.7 [+ 2.23; +71.70] mmHg, p = 0.04). HPEEP vs. MPEEP increased PaO2 (+ 22.00 [+ 1.11; +42.88] mmHg, p = 0.04) or PaO2/FiO2 (+ 42.7 [+ 2.74; +82.67] mmHg, p = 0.04). iPEEP vs. MPEEP increased PaO2/FiO2 (+ 115.2 [+ 87.21; +143.20] mmHg, p < 0.001). MPEEP vs. LPEP, and HPEEP vs. MPEEP increased PaO2 or PaO2/FiO2 significantly with different heterogeneity. HPEEP vs. LPEEP increased Cdyn (+ 7.87 [+ 1.49; +14.25] ml/mbar, p = 0.02). MPEEP vs. LPEEP, and HPEEP vs. MPEEP did not impact Cdyn (p = 0.14 and 0.38, respectively). iPEEP vs. LPEEP decreased driving pressure (-4.13 [-2.63; -5.63] mbar, p < 0.001). No significant differences in MAP or HR were found between any subgroups.

CONCLUSION

HPEEP and iPEEP during PNP in non-obese patients could promote oxygenation and increase Cdyn without clinically significant changes in MAP and HR. MPEEP could be insufficient to increase respiratory compliance and improve oxygenation. LPEEP may lead to decreased respiratory compliance and worsened oxygenation.

PROSPERO REGISTRATION

CRD42022362379; registered October 09, 2022.

Evaluation of Arterial to End-tidal Carbon Dioxide Pressure Differences during Laparoscopic Renal Surgery in the Lateral Decubitus Position

Background:

End-tidal carbon dioxide (PEtCO₂) is a noninvasive reliable technique to measure arterial partial pressure of carbon dioxide (PaCO2) in the body under general anesthesia. However, gradient between PaCO₂ and PEtCO₂ (P[a-Et] CO₂) is influenced by many factors.

Aims:

In the present study, we evaluated the changes in P (a-Et) CO₂ for laparoscopic donor nephrectomy in lateral decubitus position (LDP).

Settings and Design:

This was an observational, double-blinded, tertiary care center-based study.

Methods:

Thirty-one American Society of Anesthesiologists Class I and Class II patients of either sex undergoing laparoscopic donor nephrectomy in LDP under general anesthesia were included. An arterial cannula was inserted, PaCO₂ was measured at eight predesignated time intervals, and PEtCO₂ was also noted at the corresponding time period.

Statistical Analysis:

Data were analyzed using a two-way analysis of variance for repeated measurements using one dependent variable and one within-subject factor (time). Quantitative data were presented as mean ± standard deviation or median and interquartile range, as appropriate.

Results:

The mean P (a-Et) CO₂ gradient was 5.67 ± 1.36 mmHg 10 min after induction of anesthesia in the supine position (T1a). Ten minutes after LDP, P (a-Et) CO₂ gradient was 7.38 ± 1.45 mmHg (T1b) and was higher than T1a. The P (a-Et) CO₂ values 10 min after release of pneumoperitoneum and 10 min after making the patient supine were significantly higher than the T1a value. The highest value of P (a-Et) CO₂ gradient was at 30 min after creation of pneumoperitoneum (T30), i.e., 9.99 ± 1.70 mmHg. Pearson's correlation coefficient showed that the degree of correlation varied considerably during surgery due to interindividual variability (R² T1a vs. T60 was 0.61 vs. 0.17).

Conclusions:

PEtCO₂ does not reliably predict PaCO₂ in healthy patients scheduled for laparoscopic renal surgery in LDP.

The effect of positive end-expiratory pressure on inflammatory cytokines during laparoscopic cholecystectomy

Objectives:

To investigate effects of the positive end-expiratory pressure (PEEP) application of 10 cm H₂O on the plasma levels of cytokines during laparoscopic cholecystectomy.

Methods:

A prospective study was conducted on 40 patients who presented to the Department of General Surgery, Medical Faculty, Turgut Özal University, Ankara, Turkey scheduled for laparoscopic cholecystectomy operation during a 10 month period from September 2012 to June 2013. Forty patients scheduled for laparoscopic cholecystectomy operation were randomly divided into 2 groups; ventilation through zero end-expiratory pressure (ZEEP) (0 cm H₂O PEEP) (n=20), and PEEP (10 cm H₂O PEEP) (n=20). All patients were ventilated with 8 ml/kg TV. Levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL 10, and transforming growth factor (TGF)-β1 were measured in the pre- and post-operatively collected samples.

Results:

Blood samples of 30 patients’ were analyzed for plasma cytokine levels, and 10 were excluded from the study due to hemolysis. Post-operative plasma IL-6 levels were observed to be significantly higher than the pre-operative patients (p=0.035). Post-operative plasma TGF-β1 levels in the PEEP group was found significantly higher compared with the pre-operative group levels (p=0.033). However, there were no significant differences in the pre- and post-operative plasma cytokine levels between the 2 groups.

Conclusion:

The application of PEEP of 10 cm H₂O, which has known beneficial effect on respiratory mechanics, does not have any effect on systemic inflammatory response undergoing pneumoperitoneum during laparoscopic cholecystectomy surgery.

Laparoscopic cholecystectomy for patients with chronic obstructive pulmonary disease

PURPOSE

Laparoscopic cholecystectomy (LC) is accepted as a "gold standard" for treating most gallbladder diseases because it is superior to the open method, causes less postoperative pulmonary dysfunction, and promotes earlier postoperative recovery. The laparoscopically associated adverse effects of a carbon dioxide (CO(2)) pneumoperitoneum, however, such as hypercarbia and arterial acidosis, are more pronounced in patients with chronic obstructive pulmonary disease (COPD). The clinical results of LC for patients with COPD are analyzed in this study.

METHODS

Twenty-two patients with COPD (group 1) and undergoing LC were compared with 25 control patients without COPD and also undergoing LC (group 2). Patient demographics, intraoperative end-tidal CO(2) (both before and after CO(2) insufflation), and clinical outcome, including surgical duration, length of postoperative hospital stay, and any associated complications, were analyzed.

RESULTS

The procedure of one group 1 patient was converted to the open method, and this patient was excluded from the study. Comprising the COPD group were 20 patients with mild COPD and one patient with moderate COPD. With similar settings of tidal volume and ventilation rate for the two groups, the measured end-tidal CO(2) value was significantly greater for group 1 than for group 2 patients after the creation of a CO(2) pneumoperitoneum (34.2 +/- 2.7 vs. 30.7 +/- 3.6 mm Hg; P =.012). The duration of surgery was similar for groups 1 and 2 (88.9 +/- 36.0 vs. 83.2 +/- 38.3 minutes), as was the duration of the postoperative hospital stay (3.3 +/- 1.6 vs. 3.4 +/- 2.2 days). No pulmonary complications were noted for any of the patients.

CONCLUSIONS

LC can be safely performed in COPD patients with mild or even a moderate degree of airway obstruction. Intraoperative CO(2) retention did not complicate the postoperative recovery in terms of the complication rate or the duration of the postoperative hospital stay.