Respiratory mechanics and arterial blood gases during and after laparoscopic cholecystectomy

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.

Individualized positive end-expiratory pressure with and without recruitment maneuvers in obese patients during bariatric surgery

This study aimed to determine whether regular recruitment maneuvers (RMs) are essential for obese patients (OPs) undergoing elective laparoscopic bariatric surgery (LBS) during intraoperative ventilation with individualized positive end-expiratory pressure (PEEP). Patients were randomly assigned to two arms: the RM + PEEP_-EIT arm consisted of individualized PEEP titrated by electrical impedance tomography (EIT) with two regular RMs and the PEEP_-EIT arm consisted of individualized PEEP titrated by EIT without additional RMs. For these two arms together, EIT-guided PEEP varied among individuals. The partial pressure of oxygen in arterial blood to fractional inspired oxygen (PaO₂ /FiO₂ ) ratio in the RM + PEEP_-EIT arm was higher than that in the PEEP_-EIT arm at 1 h after pneumoperitoneum (p = 0.024) and at the end of surgery (p = 0.035). There was no great difference in the PaO₂ /FiO₂ ratio between these two arms when measured 5 min prior to postanesthesia care unit (PACU) departure and on postoperative day 1. Compared with the PEEP_-EIT arm, patients in the RM + PEEP_-EIT arm had significantly higher intraoperative dynamic respiratory system compliance (p < 0.001) but consumed more vasopressors (p = 0.036). Postoperative pulmonary complications occurred in 1 of 29 patients in the RM + PEEP_-EIT arm compared with 2 of 31 patients in the PEEP_-EIT arm. Regular lung RMs can improve intraoperative oxygenation and respiratory system compliance among OPs undergoing LBS with EIT-guided individual PEEP. However, the improvement might disappear before leaving the PACU, and regular RMs resulted in more vasopressor consumption.

Low-pressure Pneumoperitoneum With Abdominal Wall Lifting Versus Standard Pressure Pneumoperitoneum in Laparoscopic Fundoplication for Gastroesophageal Reflux Disease: A Propensity Score-matched Analysis

OBJECTIVE

The objective of this study was to compare the treatment results of low-pressure pneumoperitoneum with abdominal wall lifting (AWL+LP, 6 mm Hg) versus standard pressure pneumoperitoneum (SP, 12 mm Hg) during laparoscopic fundoplication for gastroesophageal reflux disease (GERD), using propensity score matching (PSM).

MATERIALS AND METHODS

A retrospective analysis was made of 362 patients, 123 in the AWL+LP group and 239 in the SP group, who underwent laparoscopic fundoplication for GERD from January 2010 to December 2017. Perioperative and prognostic outcomes were compared after PSM with 1:1 match.

RESULTS

After PSM, 107 matched pairs were obtained. Compared with the SP group at 30 and 60 minutes after pneumoperitoneal initiation, the AWL+LP group showed significantly lower end-tidal carbon dioxide value (P<0.001, <0.001, respectively), lower partial pressure of carbon dioxide value (P<0.001, 0.016, respectively) and significantly higher pH value (P<0.001, <0.001, respectively). However, postoperative shoulder pain, abdominal pain, and arrhythmia in the AWL+LP group were less than those in SP group (P=0.01, 0.017, 0.005, respectively). There was no significant difference in operative time (106.54±27.80 vs. 107.38±24.78 min), blood loss [15 mL (interquartile range: 12.5 to 20 mL) vs.15 mL (interquartile range: 10 to 20 mL)], length of stay (4 vs. 4 d), the wound ecchymosis [2 (1.87%) vs. 3 (2.80%)] and rates of recurrence [8 (7.48%) vs. 5 (4.67%)] between AWL+LP group and SP group.

CONCLUSION

AWL+LP resulted in comparable perioperative and prognostic outcomes with less impact on changes in cardiorespiratory function compared with SP approaches of laparoscopic fundoplication for GERD.

Effect of the "Recruitment" Maneuver on Respiratory Mechanics in Laparoscopic Sleeve Gastrectomy Surgery

Purpose

LSG surgery is used for surgical treatment of morbid obesity. Obesity, anesthesia, and pneumoperitoneum cause reduced pulmoner functions and a tendency for atelectasis. The alveolar “recruitment” maneuver (RM) keeps airway pressure high, opening alveoli, and increasing arterial oxygenation. The aim of our study is to research the effect on respiratory mechanics and arterial blood gases of performing the RM in LSG surgery.

Materials and Methods

Sixty patients undergoing LSG surgery were divided into two groups (n = 30) Patients in group R had the RM performed 5 min after desufflation with 100% oxygen, 40 cmH₂O pressure for 40 s. Group C had standard mechanical ventilation. Assessments of respiratory mechanics and arterial blood gases were made in the 10th min after induction (T1), 10th min after insufflation (T2), 5th min after desufflation (T3), and 15th min after desufflation (T4). Arterial blood gases were assessed in the 30th min (T5) in the postoperative recovery unit.

Results

In group R, values at T5, PaO₂ were significantly high, while PaCO₂ were significantly low compared with group C. Compliance in both groups reduced with pneumoperitoneum. At T4, the compliance in the recruitment group was higher. In both groups, there was an increase in PIP with pneumoperitoneum and after desufflation this was identified to reduce to levels before pneumoperitoneum.

Conclusion

Adding the RM to PEEP administration for morbidly obese patients undergoing LSG surgery is considered to be effective in improving respiratory mechanics and arterial blood gas values and can be used safely.

A prospective comparative study of arterial blood gas parameters in smoker versus non-smoker patients undergoing laparoscopic cholecystectomy

Background and Aims:

Smoking is a risk factor for postoperative pulmonary complications in patients undergoing general anaesthesia. These may get amplified with effects of pneumo-peritoneum and carbon dioxide (CO₂) insufflation during laparoscopic surgeries. Our aim was to compare metabolic and blood gas analysis of smokers versus non-smoker patients during laparoscopic surgeries under general anaesthesia.

Methods:

After permission from institutional review board, 60 patients undergoing laparoscopic cholecystectomy were divided into two groups, smokers and non-smokers (30 each). Along with baseline haemo-dynamic parameters, arterial blood gas sampling was done to assess and compare PCO₂, pH and bicarbonate (HCO₃) values at various time intervals with respect to pneumo-peritoneum creation, between smokers and non smokers.

Results:

Baseline systolic blood pressure was higher and oxygen saturation was significantly lower in smoker group. PCO₂ and end-tidal CO₂ were significantly higher in smokers at all intervals (P < 0.001). pH was significantly lower and HCO₃ higher, in smokers after creation of pneumo-peritoneum. Increase in PCO2 due to pneumo-peritoneum was higher in the smoker group (3.49 ± 8.5) mmHg versus non smoker (0.56 ± 4.86) mmHg, although statistically not significant. Change in pH and HCO₃ was similar between smokers and non-smokers.

Conclusion:

There is a significant difference in baseline arterial blood gas characteristics between smokers and non-smokers. Metabolic effects of CO₂ insufflation and increased intraabdominal pressure appears to be more enhanced in smokers.

Comparing laparoscopic cholecystectomy in patients with chronic obstructive pulmonary disease under spinal anesthesia and general anesthesia

Background

Epidemiological data demonstrate that the worldwide prevalence of chronic obstructive pulmonary disease is increasing. These patients have an increased risk of mortality and morbidity and have constant limitations in airflow. Comparing laparoscopic cholecystectomy (LC) in patients with chronic obstructive pulmonary disease (COPD) under spinal anesthesia (SA) and general anesthesia (GA).

Methods

We prospectively evaluated COPD patients who underwent laparoscopic cholecystectomy under general anesthesia (Group 1, n = 30) or spinal anesthesia (Group 2, n = 30) in our clinic between January 2016 and January 2018. Patients with COPD were further divided into groups according to their preoperative stages (Stage 1–4). Intraoperative vital findings, postoperative pain, complications, and length of hospitalization were compared between the general (GA) and spinal anesthesia (SA) groups.

Results

The mean age of the patients in the GA group was 61.0 ± 6.7 years and was 61.0 ± 7.7 years in the SA group. In the GA and SA groups, the mean ASA score was 2.8 ± 0.6 and 2.9 ± 0.6, respectively, the mean operation duration was 31.7 ± 5.1 and 30.6 ± 5.1 min, respectively, and the length of hospitalization was 3.2 ± 1.7 and 1.5 ± 0.5 days, respectively. The partial carbon dioxide rates (PaCO2) at the postoperative 5th and 20th minutes were lower in the SA group than in the GA group. Further, the requirement for postoperative analgesia was lower in the SA group, and the length of hospitalization was significantly shorter in the SA group. There was no significant difference between the two groups in terms of operation duration.

Conclusion

Laparoscopic cholecystectomy is a rather safe procedure for COPD patients under general and spinal anesthesia. However, spinal anesthesia is preferred over general anesthesia as it has better postoperative analgesia and causes no impairment of pulmonary functions.

Electronic supplementary material

The online version of this article (10.1186/s12893-018-0396-1) contains supplementary material, which is available to authorized users.

Laparoscopic cholecystectomy under neuraxial anesthesia compared with general anesthesia: Systematic review and meta-analyses

BACKGROUND

Pneumoperitoneum during laparoscopic cholecystectomy (LC) can cause hypercapnia, hypoxemia, hemodynamic changes and shoulder pain. General anesthesia (GA) enables the control of intraoperative pain and ventilation. The need for GA has been questioned by studies suggesting that neuraxial anesthesia (NA) is adequate for LC.

STUDY OBJECTIVE

To quantify the prevalence of intraoperative pain and to verify whether evidence on the maintenance of ventilation, circulation and surgical anesthesia during NA compared with GA is consistent.

DESIGN

Systematic review with meta-analyses.

SETTING

Anesthesia for laparoscopic cholecystectomy.

PATIENTS

We searched Medline, Cochrane and EBSCO databases up to 2016 for randomized controlled trials that compared LC in the two groups under study, neuraxial (subarachnoid or epidural) and general anesthesia.

MEASUREMENTS

The primary outcome was the prevalence of intraoperative pain referred to the shoulder in the NA group. Hemodynamic and respiratory outcomes and adverse effects in both groups were also collected.

MAIN RESULTS

Eleven comparative studies were considered eligible. The pooled prevalence of shoulder pain was 25%. Intraoperative hypotension and bradycardia occurred more frequently in patients who received NA, with a risk ratio of 4.61 (95% confidence interval [CI] 1.70-12.48, p=0.003) and 6.67 (95% CI 2.02-21.96, p=0.002), respectively. Postoperative nausea and vomiting was more prevalent in patients who submitted to GA. The prevalence of postoperative urinary retention did not differ between the techniques. Postoperative headache was more prevalent in patients who received NA, while the postoperative pain intensity was lower in this group. Performing meta-analyses on hypertension, hypercapnia and hypoxemia was not possible.

CONCLUSIONS

NA as sole anesthetic technique, although feasible for LC, was associated with intraoperative pain referred to the shoulder, required anesthetic conversion in 3.4% of the cases and did not demonstrate evidence of respiratory benefits for patients with normal pulmonary function.

Low-pressure capnoperitoneum reduces stress responses during pediatric laparoscopic high ligation of indirect inguinal hernia sac: A randomized controlled study

BACKGROUND

We aimed to evaluate the effect of different capnoperitoneum pressures on stress responses in pediatric laparoscopic inguinal hernia repair.

METHODS

In this prospective randomized controlled study, 68 children with indirect inguinal hernia who underwent high ligation of hernia sac were randomly divided into 3 groups: high-pressure group (12 mm Hg, HP group, n = 26); low-pressure group (8 mm Hg, LP group, n = 20); open operation group (OP group, n = 22). Heart rate (HR), blood pressure, and end-tidal CO2 (PetCO2) were recorded, as well as the levels of adrenocorticotropic hormone (ACTH) and cortisol (COR) were measured by ELISAs before operation, during operation, and after operation, respectively.

RESULTS

After establishing capnoperitoneum, HR, blood pressure, and PetCO2 were significantly increased in the HP group compared with the OP and LP groups (P < 0.05). Comparing the intraoperatively measured ACTH and COR concentrations of the HP group to the LP group, we noted higher values in the first (P < 0.05). There was no significant difference in the postoperative concentrations of ACTH and COR among the HP, LP, and OP groups.

CONCLUSIONS

Laparoscopic surgery under LP capnoperitoneum or open operation may reduce stress responses and are superior to HP capnoperitoneum.

Comparative changes in tissue oxygenation between laparoscopic and open cholecystectomy

Background

Previous studies examined the effect of laparoscopic cholecystectomy (LC) versus open cholecystectomy (OC) on physiological variables of the respiratory system. In this study we compared changes in arterial blood gases-related parameters between LC and OC to assess their comparative influence on gas exchange.

Methods

We studied 28 patients, operated under identical anesthetic protocol (LC: 18 patients, OC: 10 patients). Measurements were made on the morning before surgery (BS), the second (AS2) and the eighth (AS8) postoperative day. Studied parameters, including alveolar-arterial difference in PO₂ ((A-a)DO₂) and oxygen content (Oct in vol%), were statistically compared.

Results

On AS2 a greater increase was found in ((A-a)DO₂) for the OC compared to LC (4.673 ± 0.966 kPa versus 3.773 ± 1.357 kPa, respectively). Between BS and AS2, Oct in vol% decreased from 17.55 ± 1.90 to 15.69 ± 1.88 in the LC and from 16.99 ± 2.37 to 14.62 ± 2.23 in the OC, whilst a reduction (P = 0.093) between AS2 and AS8 was also found for the open method. Besides, on AS2, SaO₂% decrease was greater in OC compared to LC (P = 0.096).

Conclusions

On AS2, the greater increase in OC-((A-a)DO₂) associated with Oct in vol% and SaO₂% findings also in OC group suggest that LC might be associated with lower risk for impaired tissue oxygenation.

Evidence for negative effects of elevated intra-abdominal pressure on pulmonary mechanics and oxidative stress

OBJECTIVE

To compare the effects of pneumoperitoneum on lung mechanics, end-tidal CO2 (ETCO2), arterial blood gases (ABG), and oxidative stress markers in blood and bronchoalveolar lavage fluid (BALF) during laparoscopic cholecystectomy (LC) by using lung-protective ventilation strategy.

MATERIALS AND METHODS

Forty-six patients undergoing LC and abdominal wall hernia (AWH) surgery were assigned into 2 groups. Measurements and blood samples were obtained before, during pneumoperitoneum, and at the end of surgery. BALF samples were obtained after anesthesia induction and at the end of surgery.

RESULTS

Peak inspiratory pressure, ETCO2, and pCO2 values at the 30th minute were significantly increased, while there was a significant decrease in dynamic lung compliance, pH, and pO2 values in LC group. In BALF samples, total oxidant status (TOS), arylesterase, paraoxonase, and malondialdehyde levels were significantly increased; the glutathione peroxidase levels were significantly decreased in LC group. The serum levels of TOS and paraoxonase were significantly higher at the end of surgery in LC group. In addition, arylesterase level in the 30th minute was increased compared to baseline. Serum paraoxonase level at the end of surgery was significantly increased when compared to AWH group.

CONCLUSIONS

Our study showed negative effects of pneumoperitoneum in both lung and systemic levels despite lung-protective ventilation strategy.

Effects of laparoscopic cholecystectomy on lung function: A systematic review

AIM: To present and integrate findings of studies investigating the effects of laparoscopic cholecystectomy on various aspects of lung function.

METHODS: We extensively reviewed literature of the past 24 years concerning the effects of laparoscopic cholecystectomy in comparison to the open procedure on many aspects of lung function including spirometric values, arterial blood gases, respiratory muscle performance and aspects of breathing control, by critically analyzing physiopathologic interpretations and clinically important conclusions. A total of thirty-four articles were used to extract information for the meta-analysis concerning the impact of the laparoscopic procedure on lung function and respiratory physiopathology. The quality of the literature reviewed was evaluated by the number of their citations and the total impact factor of the corresponding journals. A fixed and random effect meta-analysis was used to estimate the pooled standardized mean difference of studied parameters for laparoscopic (LC) and open (OC) procedures. A crude comparison of the two methods using all available information was performed testing the postoperative values expressed as percentages of the preoperative ones using the Mann-Whitney two-sample test.

RESULTS: Most of the relevant studies have investigated and compared changes in spirometric parameters.The median percentage and interquartile range (IQR) of preoperative values in forced vital capacity (FVC), forced expiratory volume in 1 s and forced expiratory flow (FEF) at 25%-75% of FVC (FEF_25%-75%) expressed as percentage of their preoperative values 24 h after LC and OC were respectively as follows: [77.6 (73.0, 80.0) L vs 55.4 (50.0, 64.0) L, P < 0.001; 76.0 (72.3, 81.0) L vs 52.5 (50.0, 56.7) L, P < 0.001; and 78.8 (68.8, 80.9) L/s vs 60.0 (36.1, 66.1) L/s, P = 0.005]. Concerning arterial blood gases, partial pressure of oxygen [PaO₂ (kPa)] at 24 or 48 h after surgical treatment showed reductions that were significantly greater in OC compared with LC [LC median 1.0, IQR (0.6, 1.3); OC median 2.4, IQR (1.2, 2.6), P = 0.019]. Fewer studies have investigated the effect of LC on respiratory muscle performance showing less impact of this surgical method on maximal respiratory pressures (P < 0.01); and changes in the control of breathing after LC evidenced by increase in mean inspiratory impedance (P < 0.001) and minimal reduction of duty cycle (P = 0.01) compared with preoperative data.

CONCLUSION: Laparoscopic cholecystectomy seems to be associated with less postoperative derangement of lung function compared to the open procedure.

Effects of elevated artificial pneumoperitoneum pressure on invasive blood pressure and levels of blood gases

BACKGROUND AND OBJECTIVE

to evaluate the clinical, hemodynamic, gas analysis and metabolic repercussions of high transient pressures of pneumoperitoneum for a short period of time to ensure greater security for introduction of the first trocar.

METHODS

sixty-seven patients undergoing laparoscopic procedures were studied and randomly distributed in P12 group: n=30 (intraperitoneal pressure [IPP] 12mmHg) and P20 group: n=37 (IPP of 20mmHg). Mean arterial pressure (MAP) was evaluated by catheterization of the radial artery; and through gas analysis, pH, partial pressure of oxygen (PaO2), partial pressure of CO2 (PaCO2), bicarbonate (HCO3) and alkalinity (BE) were evaluated. These parameters were measured in both groups at time zero before pneumoperitoneum (TP0); at time 1 (TP1) when IPP reaches 12mmHg in both groups; at time 2 (TP2) after five min with IPP=12mmHg in P12 and after 5min with IPP=20mmHg at P20; and at time 3 (TP3) after 10min with IPP=12mmHg in P12 and with return of IPP from 20 to 12mmHg, starting 10min after TP1 in P20. Different values from those considered normal for all parameters assessed, or the appearance of atypical organic phenomena, were considered as clinical changes.

RESULTS

there were statistically significant differences in P20 group in MAP, pH, HCO3 and BE, but within normal limits. No clinical and pathological changes were observed.

CONCLUSIONS

high and transient intra-abdominal pressure causes changes in MAP, pH, HCO3 and BE, but without any clinical impact on the patient.

Effects of elevated artificial pneumoperitoneum pressure on invasive blood pressure and levels of blood gases

BACKGROUND AND OBJECTIVE

to evaluate the clinical, hemodynamic, gas analysis and metabolic repercussions of high transient pressures of pneumoperitoneum for a short period of time to ensure greater security for introduction of the first trocar.

METHODS

sixty-seven patients undergoing laparoscopic procedures were studied and randomly distributed in P12 group: n=30 (intraperitoneal pressure [IPP] 12mmHg) and P20 group: n=37 (IPP of 20mmHg). Mean arterial pressure (MAP) was evaluated by catheterization of the radial artery; and through gas analysis, pH, partial pressure of oxygen (PaO2), partial pressure of CO2 (PaCO2), bicarbonate (HCO3) and alkalinity (BE) were evaluated. These parameters were measured in both groups at time zero before pneumoperitoneum (TP0); at time 1 (TP1) when IPP reaches 12mmHg in both groups; at time 2 (TP2) after five min with IPP=12mmHg in P12 and after 5min with IPP=20mmHg at P20; and at time 3 (TP3) after 10min with IPP=12mmHg in P12 and with return of IPP from 20 to 12mmHg, starting 10min after TP1 in P20. Different values from those considered normal for all parameters assessed, or the appearance of atypical organic phenomena, were considered as clinical changes.

RESULTS

there were statistically significant differences in P20 group in MAP, pH, HCO3 and BE, but within normal limits. No clinical and pathological changes were observed.

CONCLUSIONS

high and transient intra-abdominal pressure causes changes in MAP, pH, HCO3 and BE, but without any clinical impact on the patient.

Comparison of transcutaneous, arterial and end-tidal measurements of carbon dioxide during laparoscopic cholecystectomy in patients with chronic obstructive pulmonary disease

OBJECTIVE

Transcutaneous, arterial and end-tidal measurements of carbon dioxide were compared in patients (American Society of Anesthesiology physical status classes II and III) with chronic obstructive pulmonary disease (COPD) who underwent laparoscopic cholecystectomy with carbon dioxide insufflation.

METHODS

General anaesthesia was performed in all patients. The Sentec(®) system was used for transcutaneous monitoring of the partial pressure of carbon dioxide (TcPCO(2)). TcPCO(2) and arterial partial pressure of carbon dioxide (PaCO(2)) were recorded preoperatively, after induction of anaesthesia, during insufflation and postoperatively; end-tidal carbon dioxide (ETCO(2)) was recorded after induction and during insufflation.

RESULTS

PaCO(2) increased during insufflation and reached a maximum at extubation. It declined within 20 min postoperatively but did not return to preoperative levels during this time. TcPCO(2) levels followed a similar pattern. ETCO(2) was significantly lower than PaCO(2) after induction and during insufflation.

CONCLUSION

TcPCO(2) was a valid and practical measurement compared with ETCO(2). In patients with COPD undergoing laparoscopic cholecystectomy, TcPCO(2) and ETCO(2) could be used instead of arterial blood gas sampling.

Effects of pneumoperitoneum and positioning on respiratory mechanics in chronic obstructive pulmonary disease patients during Nissen fundoplication

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the effects of pneumoperitoneum and patient positioning on respiratory mechanics and blood gases in chronic obstructive pulmonary disease (COPD) patients during laparoscopic Nissen fundoplication.

METHODS

After the approval of the Ethical Committee, 32 patients were divided into 2 groups as COPD patients (n=16) and normal patients (n=16). Dynamic respiratory compliance (Cdyn), airway resistance, and peak inspiratory pressure were monitored. Measurements were made in 5 time points: after intubation (intubation), Trendelenburg position (Trendelenburg), during laparoscopic Nissen fundoplication surgery after pneumoperitoneum with the Fowler position (Fowler), right before the desufflation with Fowler position (Fowler-end), and after the desufflation in supine position (supine). Samples of arterial blood gases were collected at the same periods.

RESULTS

At all periods, there was a significant decrease in Cdyn and arterial oxygen pressure in 2 groups. Although pneumoperitoneum did not exist during Trendelenburg position, the Cdyn (38+/-13 mL cm H2O(-1)) found to be significantly decreased in COPD patients. In 2 groups, the lowest Cdyn value detected during the Fowler-end period was 43+/-8 mL cm H2O(-1) in control group and 34+/-11 mL cm H2O(-1) in COPD group. Whereas the pH decreased at Fowler, Fowler-end, and supine period, arterial carbon dioxide pressure increased (P<0.05). There was no difference for the other parameters.

CONCLUSIONS

In COPD patients, Trendelenburg position has negative effect on respiratory mechanics. Pneumoperitoneum and other positions have similar effect on respiratory mechanics in COPD and control patients.

Peritoneal acidosis mediates immunoprotection in laparoscopic surgery

BACKGROUND

We have shown previously that abdominal insufflation with CO(2) increases serum levels of IL-10 and TNFalpha and increases survival among animals with lipopolysaccharide (LPS)-induced sepsis, even after a laparotomy. We demonstrated previously that the effect of CO(2) is not from changes in systemic pH, although the peritoneum is locally acidotic during abdominal insufflation with CO(2) even when systemic pH is corrected. We hypothesized that acidification of the peritoneum via means other than CO(2) insufflation would produce alterations in the inflammatory response similar to those associated with CO(2) pneumoperitoneum.

METHODS

In total, 42 rats were randomized into 7 groups (n = 6): 1) LPS only, 2) anesthesia control, 3) helium pneumoperitoneum, 4) CO(2) pneumoperitoneum, 5) buffered mild acid lavage, 6) buffered strong acid lavage, and 7) buffered strong acid lavage + helium pneumoperitoneum. Animals received anesthesia with vaporized isoflurane (except the LPS-only group) and their respective abdominal treatment (pneumoperitoneum and/or lavage) for 30 min followed immediately by stimulation with systemic LPS (1 mg/kg, IV). Blood was harvested via cardiac puncture 60 min after LPS injection, and serum levels of IL-10 and TNFalpha levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Mean peritoneal pH decreased (P < .05) after CO(2) pneumoperitoneum, buffered strong acid lavage, and buffered strong acid lavage + helium pneumoperitoneum, and it decreased (P = .1) after helium pneumoperitoneum alone and buffered mild acid lavage. IL-10 levels were increased (P < .01), and TNFalpha levels decreased (P < .001) among animals with acidic peritoneal cavities compared with animals with pH-normal peritoneal cavities. Decreasing peritoneal pH correlated with both increasing IL-10 levels (r = -.465, P < .01) and decreasing TNFalpha levels (r = 0.448, P < .01). Among animals with peritoneal acidosis, there were no differences in levels of IL-10 or TNFalpha regardless of insufflation status (P > .05 for both cytokines).

CONCLUSIONS

Acidification of the peritoneal cavity whether by abdominal insufflation or by peritoneal acid lavage increases serum IL-10 and decreases serum TNFalpha levels in response to systemic LPS challenge. The degree of peritoneal acidification correlates with the degree of inflammatory response reduction. These results support the hypothesis that pneumoperitoneum-mediated attenuation of the inflammatory response after laparoscopic surgery occurs via a mechanism of peritoneal cell acidification.

The effect of low-flow sevoflurane and desflurane on pulmonary mechanics during laparoscopic surgery

BACKGROUND

This study was designed to investigate the effects of inhaled anesthetic agents on respiratory mechanics with low flow anesthesia in laparoscopic abdominal surgery. Two inhaled anesthetics, desflurane and sevoflurane, have a lower solubility in blood and tissues than all previous volatile anesthetics, and have become the preferred volatile anesthetics for routine surgical procedures.

METHODS

Twenty-six patients were examined. Patients were randomly assigned to two groups, to receive sevoflurane (n = 13) or desflurane (n = 13). Tidal volume and ventilation rate were kept unchanged throughout the operation. Intra-abdominal pressure was kept constant at the level of 12 mm Hg. Respiratory mechanics such as peak inspiratory pressure (PIP), respiratory resistance (Rr), and dynamic compliance (Cdyn) measurements were recorded by a Datex-Ohmeda respiratory device (Datex-Ohmeda, Finland) at four timepoints: 5 minutes after mechanical ventilation started (T1), after insufflation of the peritoneum (T2), in the 30-degree Trendelenburg position (T3), and after desufflation of the peritoneum (T4).

RESULTS

In our study, desflurane caused a statistically significant increase in PIP and Rr and decrease in C(dyn). When the two groups were compared, Rr values in the deslurane group showed significant increases at T2, T3, and T4 compared to the sevoflurane group (P < 0.05). These values did not change in the sevoflurane group, while PIP significantly increased at T2, T3, and T4 after desufflation in the desflurane group (P < 0.05). Cdyn values decreased significantly at all 4 timepoints in the desflurane group compared to the sevoflurane group (P < 0.05).

CONCLUSION

We concluded that respiratory mechanics were affected by desflurane with low flow anesthesia in patients undergoing laparoscopic abdominal surgery. No significant influence on respiratory mechanics was seen with sevoflurane anesthesia.

Repercussões respiratórias do pneumoperitônio induzido em suínos

Objetivo: Estudar, na faixa tida como segura, as repercussões respiratórias de diferentes pressões de pneumoperitônio, com dióxido de carbono, induzido em suínos. Métodos: Foram utilizados 14 suínos machos, da raça Landrace, pesando entre cinco e sete quilos, com 30 a 45 dias de idade. A amostra foi subdividida igualitariamente em Grupo A (pneumoperitônio com 10mmHg durante 60 minutos) e Grupo B (pneumoperitônio com 15mmHg durante 60 minutos). Após a indução anestésica, os animais foram intubados, sendo monitorado o volume corrente (VC) e a saturação periférica de oxigênio (SpO2). Resultados: Não houve diferença estatística nos valores do VC e SpO2 antes, durante e após a indução do pneumoperitônio. Conclusão: O pneumoperitônio, nos níveis pressóricos de 10 a 15mmHg, não causou alteração significativa nos padrões respiratórios de suínos, durante o período de tempo estudado.

Cerebral blood flow velocity alterations, under two different carbon dioxide management strategies, during sevoflurane anesthesia in gynecological laparoscopic surgery

In this study, 33 female patients, scheduled for operative gynecological laparoscopies, were enrolled. Our aim was prospective, randomized comparison of the influence of two different management strategies, regarding end tidal CO2, on cerebral blood flow velocities and on pulsatility index, examined by means of transcranial Doppler ultrasonography, under sevoflurane anesthesia 1.3 MAC: permissive hypercapnia (up to 45 mmHg, Group I, n = 17) versus intervention to ensure mild hypocapnia, (around 33 mmHg, Group II, n = 16). Baseline measurements of investigated parameters were recorded and CO2 insufflation started. In Group I no further adjustment was performed and CO2 partial pressure rose, while in Group II it was kept stable, by ventilatory patterns adjustment. Hemodynamic, acid base balance and cerebrovascular variables were recorded during pneumoperitoneum and in post-desufflation period, at eight checking time points. In Group I cerebral blood flow velocities increased according to CO2 elevation (2.3%-3.9% per mmHg of increase in CO2 partial pressure), whereas in Group II no significant alterations were noticed. Pulsatility index was constant over time without clinical differences between groups. Our study suggests that under sevoflurane anesthesia 1.3 MAC, prophylactic hyperventilation limits the cerebral blood flow velocities enhancing effect of CO2 insufflation, during laparoscopies.

Effect of CO(2) pneumoperitoneum on ventilation-perfusion relationships during laparoscopic cholecystectomy

BACKGROUND

Previous studies have shown that pneumoperitoneum transiently reduces venous admixture as assessed by a calculation based on the shunt formula, and increases arterial oxygen tension (PaO(2)) in patients without heart or lung disease. The aim of the present study was to further explore the relationship between ventilation-perfusion (V(A)/Q) before and during pneumoperitoneum by using the multiple inert gas technique.

METHODS

Nine patients without heart or lung disease (ASA I), with a mean age of 42 years, scheduled for laparoscopic cholecystectomy were included. After premedication and induction of anaesthesia, radial artery and pulmonary artery catheters were introduced percutaneously. The V(A)Q relationships were evaluated by the multiple inert gas elimination technique before and during pneumoperitoneum to obtain a direct measure of the pulmonary shunt.

RESULTS

Induction of pneumoperitoneum decreased the pulmonary shunt from 5.8 (4.5) to 4.1 (3.2)% (P<0.05) and increased PaO(2) from 21.7 (5.9) to 24.7 (4.8) kPa (P<0.01). During surgery, the shunt increased from 3.2 (2.8) to 5.2 (3.4)% to the same level as before pneumoperitoneum induction. No area with low V(A)Q was seen. Dead space ventilation amounted to 20.0 (1.2)% in the supine position and did not change during the investigation.

CONCLUSIONS

In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg causes a transient reduction of the pulmonary shunt. The mechanisms underlying the present finding remain to be elucidated.

[Recovery of lung function after laparoscopic cholecystectomy: the role of postoperative pain]

OBJECTIVES

Lung function has been shown to deteriorate after laparoscopic cholecystectomy (LC). The present study evaluated 1) the rate of recovery after LC, and 2) the pathogenic role of postoperative pain in functional deterioration.

DESIGN

Lung function was measured 24 hours before LC, upon hospital discharge (48-72 h after LC), and 10 days later. All patients received metamizol after LC until discharge (2 g every 6 h i.v.). Half the patients (analgesia group) received tramadol (150 mg i.m.) 30 minutes before lung function testing on the day of hospital discharge. The remaining patients constituted the control group.

PATIENTS

Twenty healthy subjects (53 4 years old) undergoing LC for gall bladder removal. All signed informed consent forms. Measures and outcomes: Patient characteristics and preoperative lung function results were similar in both groups. LC duration and postoperative course were also similar in both groups. All were discharged without complications within 72 hours after LC. Lung function upon discharge (FVC, FEV1, TLC, PaO2 and AaPO2) had deteriorated in both groups (p<0.001). Deterioration was less marked in the analgesia group (p < 0.05). Ten days later, lung function had normalized for all subjects.

CONCLUSIONS

These results indicate that after LC, 1) lung function is still abnormal when the patient is discharged from hospital, 2) lung function has fully recovered within 10 days, and 3) postoperative pain contributes significantly to temporary deterioration in lung function.