Pathophysiology of laparoscopy

Which intraperitoneal insufflation pressure should be used for less postoperative pain in transperitoneal laparoscopic urologic surgeries?

Purpose

To determine whether using different intraperitoneal insufflation pressures for transperitoneal laparoscopic urologic surgeries decreases postoperative pain.

Materials and Methods

76 patients who underwent transperitoneal laparoscopic upper urinary tract surgery at different insufflation pressures were allocated into the following groups: 10mmHg (group I, n=24), 12mmHg (group II, n=25) and 14mmHg (group III, n=27). These patients were compared according to age, gender, body mass index (BMI), type and duration of surgery, intraoperative bleeding volume, postoperative pain score and length of hospital stay. A visual analog scale (VAS) was used for postoperative pain.

Results

Demographic characteristics, mean age, gender, BMI and type of surgeries were statistically similar among the groups. The mean operation time was higher in group I than group II and group III but this was not statistically significant (P=0.810). The mean intraoperative bleeding volume was significantly higher in group I compared with group II and group III (P=0.030 and P=0.006). The mean length of postoperative hospital stays was statistically similar among the groups (P=0.849). The mean VAS score at 6h was significantly reduced in group I compared with group III (P=0.011). At 12h, the mean VAS score was significantly reduced in group I compared with group II and group III (P=0.009 and P<0.001). There was no significant difference in the mean VAS scores at 24h among three groups (P=0.920).

Conclusion

Lower insufflation pressures are associated with lower postoperative pain scores in the early postoperative period.

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.

A prospective randomized trial of postoperative pain following different insufflation pressures during gynecologic laparoscopy

OBJECTIVE

To determine the effects of different intra-abdominal pressure values on visceral pain following gynecologic laparoscopic surgery in the Trendelenburg position.

STUDY DESIGN

This randomized, controlled prospective trial was conducted at a tertiary education hospital and included 150 patients who underwent gynecologic laparoscopy with different abdominal insufflation pressures. There were 54 patients in the 8 mmHg low pressure group (LPG), 45 in the 12 mmHg standard pressure group (SPG), and 51 in the 15 mmHg high pressure group (HPG). We assessed mean age, body mass index (BMI), duration of surgery, analgesic consumption, length of hospital stay, amount of CO2 expended and volume of hemorrhage. Visceral pain and referred visceral pain were assessed 6, 12, and 24 h postoperatively using a visual analog scale (VAS).

RESULTS

There was no significant difference in age, BMI, analgesic consumption or length of hospital stay among groups. The mean operative time and total CO2 expended during surgery were higher in the LPG compared with the SPG and HPG. The mean intensity of postoperative pain assessed by the VAS score at 6 and 12 h was less in the LPG than in the SPG and HPG and was reduced significantly at 12 h. VAS scores at 24 h in the LPG and SPG were lower than in the HPG.

CONCLUSION

Pain is reduced by low insufflation pressure compared with standard and high insufflation pressure following gynecologic laparoscopic surgery in the Trendelenburg position. However, low insufflation pressure may result in longer operation times and increased hemorrhage.

Cardiovascular implications of abdominal compartment syndrome

Cardiovascular dysfunction and failure are commonly encountered in the patient with intra-abdominal hypertension or abdominal compartment syndrome. Accurate assessment and optimization of preload, contractility, and afterload, in conjunction with appropriate goal-directed resuscitation and abdominal decompression when indicated, are essential to restoring end-organ perfusion and maximizing patient survival. The validity of traditional hemodynamic resuscitation endpoints, such as pulmonary artery occlusion pressure and central venous pressure, must be reconsidered in the patient with intra-abdominal hypertension as these pressure-based estimates of intravascular volume have significant limitations in patients with elevated intra-abdominal pressure. If such limitations are not recognized, misinterpretation of the patient's cardiac status is likely, resulting in inappropriate and potentially detrimental therapy. Appropriate fluid administration is mandatory as under-resuscitation leads to organ failure and over-resuscitation the development of secondary abdominal compartment syndrome, both of which are associated with increased morbidity and mortality. Volumetric monitoring techniques have been proven to be superior to traditional intra-cardiac filling pressures in directing the appropriate resuscitation of this patient population. Calculation of the "abdominal perfusion pressure", defined as mean arterial pressure minus intra-abdominal pressure, has been shown to be a beneficial resuscitation endpoint as it assesses not only the severity of the patient's intra-abdominal hypertension, but also the adequacy of abdominal blood flow. Application of a goal-directed resuscitation strategy, including abdominal decompression when indicated, improves cardiac function, reverses end-organ failure, and minimizes intra-abdominal hypertension-related patient morbidity and mortality.

Gasless laparoscopic surgery during pregnancy: evaluation of its role and usefulness

The minimally invasive laparoscopic approach in the surgical treatment of diseases during pregnancy has become progressively more accepted and applied. In an attempt to overcome the potential adverse effects of pneumoperitoneum on the fetus, gasless laparoscopic surgery (GLS) has been developed. This article reviews the evidence available for the role and effectiveness of GLS in pregnancy. A computerized literature search was conducted on Medline, Science Citation Index, Current Contents, Embase, and PubMed databases for English language publications from the first report of GLS in pregnancy in 1995 to June 2012. Eleven case reports or retrospective series were identified. A total of 44 pregnant women underwent GLS for various surgical indications. In all cases, the procedures were carried out without complication, and the women were discharged from hospital with a continuing pregnancy. GLS in pregnancy has comparable outcomes to conventional CO2 laparoscopy, but it is associated with some advantages. Hypercarbia and increased intraperitoneal pressure due to CO2 insufflation are avoided. The use of high-pressure continuous suction may prevent the problems that are potentially associated with intra-abdominal smoke generated by electrosurgery, which can increase the risk of fetal exposure to elevated levels of toxic gases. Because this procedure may be performed under regional anesthesia, avoiding general anesthesia, there is a minimal transplacental passage of anesthetic drugs to the fetus. The surgeon must be expert in advanced laparoscopic procedures.

Oxidative stress response after laparoscopic versus conventional sigmoid resection: a randomized, double-blind clinical trial

Surgery is accompanied by a surgical stress response, which results in increased morbidity and mortality. Oxidative stress is a part of the surgical stress response. Minimally invasive laparoscopic surgery may result in reduced oxidative stress compared with open surgery. Nineteen patients scheduled for sigmoid resection were randomly allocated to open or laparoscopic sigmoid resection in a double-blind, prospective clinical trial. Three biochemical markers of oxidative stress (malondialdehyde, ascorbic acid, and dehydroascorbic acid) were measured at 6 different time points (preoperatively, 1 h, 6 h, 24 h, 48 h, and 72 h postoperatively). There were no statistical significant differences between laparoscopic and open surgery for any of the 3 oxidative stress parameters. Malondialdehyde was reduced 1 hour postoperatively (P<0.001) for all 19 patients. There was a significant drop in ascorbic acid at 1 hour and 6 hours after the first abdominal incision (P=0.002) for all 19 patients. Laparoscopic surgery was not found to be associated with reduced oxidative stress.

Improved ventilation-perfusion matching with increasing abdominal pressure during CO(2) -pneumoperitoneum in pigs

BACKGROUND

CO(2) -pneumoperitoneum (PP) is performed at varying abdominal pressures. We studied in an animal preparation the effect of increasing abdominal pressures on gas exchange during PP.

METHODS

Eighteen anaesthetized pigs were studied. Three abdominal pressures (8, 12 and 16 mmHg) were randomly selected in each animal. In six pigs, single-photon emission computed tomography (SPECT) was used for the analysis of V/Q distributions; in another six pigs, multiple inert gas elimination technique (MIGET) was used for assessing V/Q matching. In further six pigs, computed tomography (CT) was performed for the analysis of regional aeration. MIGET, CT and central haemodynamics and pulmonary gas exchange were recorded during anaesthesia and after 60 min on each of the three abdominal pressures. SPECT was performed three times, corresponding to each PP level.

RESULTS

Atelectasis, as assessed by CT, increased during PP and in proportion to abdominal pressure [from 9 ± 2% (mean ± standard deviation) at 8 mmHg to 15 ± 2% at 16 mmHg, P<0.05]. SPECT during increasing abdominal CO(2) pressures showed a shift of blood flow towards better ventilated areas. V/Q analysis by MIGET showed no change in shunt during 8 mmHg PP (9 ± 1.9% compared with baseline 9 ± 1.2%) but a decrease during 12 mmHg PP (7 ± 0.9%, P<0.05) and 16 mmHg PP (5 ± 1%, P<0.01). PaO(2) increased from 39 ± 10 to 52 ± 9 kPa (baseline to 16 mmHg PP, P<0.01). Arterial carbon dioxide (PCO(2) ) increased during PP and increased further with increasing abdominal pressures.

CONCLUSION

With increasing abdominal pressure during PP perfusion was redistributed more than ventilation away from dorsal, collapsed lung regions. This resulted in a better V/Q match. A possible mechanism is enhanced hypoxic pulmonary vasoconstriction mediated by increasing PCO(2) .

Abdominal compartment syndrome: pathophysiology and definitions

"Intra-abdominal hypertension", the presence of elevated intra-abdominal pressure, and "abdominal compartment syndrome", the development of pressure-induced organ-dysfunction and failure, have been increasingly recognized over the past decade as causes of significant morbidity and mortality among critically ill surgical and medical patients. Elevated intra-abdominal pressure can cause significant impairment of cardiac, pulmonary, renal, gastrointestinal, hepatic, and central nervous system function. The significant prognostic value of elevated intra-abdominal pressure has prompted many intensive care units to adopt measurement of this physiologic parameter as a routine vital sign in patients at risk. A thorough understanding of the pathophysiologic implications of elevated intra-abdominal pressure is fundamental to 1) recognizing the presence of intra-abdominal hypertension and abdominal compartment syndrome, 2) effectively resuscitating patients afflicted by these potentially life-threatening diseases, and 3) preventing the development of intra-abdominal pressure-induced end-organ dysfunction and failure. The currently accepted consensus definitions surrounding the diagnosis and treatment of intra-abdominal hypertension and abdominal compartment syndrome are presented.

Esophageal Doppler (ODM II) improves intraoperative hemodynamic monitoring during laparoscopic surgery

Minimally invasive laparoscopic surgery has been expanded to the elderly and high-risk surgical patients with underlying cardiac and pulmonary disease. However, possible cardiovascular changes during CO2 pneumoperitoneum necessitate close intraoperative monitoring. In this prospective study, 55 patients (mean age 62.52 years, range 26-82) undergoing laparoscopic surgery were included. Patients were categorized into 3 groups of low (group A: 12 patients, mean age 55.5 years), moderate (group B: 22 patients, mean age 59.5 years), and high (group C: 21 patients, mean age 69.71 years) surgical risk according to ASA physical status classification. Similar anesthetic agents and anesthetic techniques were used in the above cases. An esophageal Doppler (ODM II, Abbott Laboratories) was used to measure aortic blood flow velocity and thereby estimating stroke volume (SVe) and cardiac output (COe) throughout anesthesia, in addition to traditional monitoring. After abdominal insufflation (peak intra-abdominal pressure: 13-15 mm Hg) COe values decreased from the initial value after induction of anesthesia by 22%, 20%, and 18% for groups A, B, and C, respectively (P < 0.05). The above values further deteriorated (25%, 28%, and 30% for groups A, B, and C, respectively) in the anti-Trendelenburg positioning of the patient. The peak aortic blood flow velocity (PV) followed the changes, thus indicating that heart muscle contractility is affected during the procedure. Stabilization of the above values was achieved after 20 minutes of CO(2) pneumoperitoneum and improvement was noted only after deflation of the abdomen. Heart rate and blood pressure essentially remained unchanged throughout the procedure, although the final values were increased compared with initial. Insufflation of the abdomen with CO(2) produces measurable effects on the cardiovascular system that require reappraisal of hemodynamic monitoring during anesthesia. ODM II offers a reliable, relatively noninvasive, cost-effective tool for intraoperative monitoring of the hemodynamic changes with a potential for future application for improvement of intraoperative hemodynamic status of patients.

Effects of enalaprilat on the renin-angiotensin-aldosterone system and on renal function during CO2 pneumoperitoneum

BACKGROUND AND PURPOSE

Mechanical and hormonal factors have been implicated in pneumoperitoneum-induced renal alterations. The aim of this study was to evaluate the effects of enalaprilat (Vasotec) administration on renal function during CO2 pneumoperitoneum, given that this drug, which is an angiotensin-converting enzyme inhibitor, by inhibiting the renin-angiotensin-aldosterone system, alters hormone-induced changes during pneumoperitoneum.

MATERIALS AND METHODS

Thirty adult dogs were randomly assigned to one of three groups (N = 10 each): group A (pneumoperitoneum not performed); group B (CO2 + enalaprilat); group C CO2 only. The groups were analyzed with consideration for body weight, hematologic values, hemodynamic parameters, and renal function (plasma renin activity, urinary debt, creatinine clearance, and sodium-excretory fraction).

RESULTS

Hemodynamic and acid-basic parameter differences did not influence renal function. Plasma renin activity decreased significantly in group B compared with group C and stayed close to the values in group A. Creatinine clearance remained constant in group B, while in group C, creatinine clearance dropped, and this difference was statistically significant. Urinary debt and sodium-excretory fraction increased in group B during pneumoperitoneum and 60 minutes after this period in comparison with the other groups without reaching statistical significance.

CONCLUSION

The decline in urinary debt and in creatinine clearance observed during pneumoperitoneum was less accentuated with administration of enalaprilat.

Decreased cardiac output in humans during laparoscopic antireflux surgery: direct measurements

OBJECTIVE

In a porcine model, we demonstrated that laparoscopic Nissen fundoplication causes a significant drop in cardiac output (30%) because it exposes both the peritoneal cavity and the mediastinum to CO(2) under pressure. To determine if this occurs in humans, we examined cardiovascular physiology during laparoscopic Nissen fundoplication. Because of invasiveness required in this pilot trial, only six patients were studied.

METHODS

The arterial blood pressure (via radial arterial catheter) and the pulmonary artery diastolic pressure and cardiac index (via pulmonary artery thermodilution catheter) were measured at seven points in time during each laparoscopic Nissen fundoplication.

RESULTS

The systolic blood pressure decreased in all patients, and the cardiac index decreased in all but one patient. The exception was a patient with Huntington disease, in whom the cardiac output did not decrease. In four of the five patients, the cardiac output was lowest during hiatal dissection, and in the fifth, it was lowest after reverse Trendelenburg positioning. No significant change in the pulmonary artery diastolic pressure was noted. All patients received adequate intravenous fluid replacement (average, 58 +/- 16 mL/kg) to support blood pressure. In one patient, with a particularly large paraesophageal hernia, profound hypotension (40/25 mm Hg) developed during the mediastinal phase of the procedure, and this patient required alpha-adrenergic support followed by laparotomy to eliminate a surgical cause (none found).

CONCLUSIONS

Although it is a tremendous advance for patients, laparoscopic Nissen fundoplication can be associated with a significant reduction in cardiac output and blood pressure. Surgeons and anesthesiologists must be alert to changes reflecting these decreases during procedures, which violate both the peritoneal cavity and the mediastinum. We propose careful hemodynamic monitoring during these procedures, especially in patients with coronary artery disease or significant left ventricular dysfunction.

Laparoscopic Nissen fundoplication with carbon dioxide pneumoperitoneum preserves cell-mediated immunity in an immature animal model

PURPOSE

The aim of this study is to elucidate the effects of laparoscopic Nissen fundoplication (LNF) with carbon dioxide (CO(2)) or helium (He) on the cell-mediated immune response in a pediatric animal model compared with open Nissen fundoplication (ONF).

METHODS

Cell immune response was evaluated in 45 1-week-old Sprague Dawley rats using the delayed type hypersensitivity (DTH) skin test. Animals were sensitized against keyhole limpet hemocyanin (KLH) by subcutaneous injection (0.5 mg) in complete Freund's adjuvant. Animals were challenged 2 weeks later by an intradermal injection of KLH (0.3 mg) in sterile saline (challenge 1, baseline). Rats with positive DTH skin reaction at 24 and 48 hours after challenge 1 were put randomly into 4 groups (n = 10 each): I, only anesthesia (control); II, LNF with CO(2), III, LNF with He; IV, ONF. Animals were injected intradermally with KLH (0.3 mg) immediately before the procedures (challenge 2) and 3 and 6 days postoperatively (challenges 3 and 4).

RESULTS

DTH skin reactions were measured 24 and 48 hours after each challenge. There were no significant changes in cell-mediated immunosuppression after LNF with CO(2). However, a transient cell-mediated immunosuppression was observed after LNF with He and ONF. All fundoplications were intact at the time of necropsy.

CONCLUSIONS

These data suggest a transient suppression of cell-mediated immunity in open procedures when compared with laparoscopic interventions using CO(2) in a pediatric animal model. In addition, the type of gas used during laparoscopy also may modulate this transient immunosuppression.

Cell-mediated immune response is better preserved by laparoscopy than laparotomy

BACKGROUND

This study compares the effects of carbon dioxide pneumoperitoneum versus laparotomy on cellular-mediated immune response in a murine model.

METHODS

Sixty-eight female C3H/He mice were sensitized to keyhole limpet hemocyanin (KLH) and to a mouse mammary carcinoma cell line (MC2) before surgery. Animals were randomized into 4 groups: group I, anesthesia (control); group II, pneumoperitoneum with carbon dioxide; group III, extraperitoneal wound; group IV, laparotomy. All animals were challenged subsequently with KLH and MC2 tumor cells. Delayed-type hypersensitivity skin reaction (DTH) to KLH was measured on postoperative days (PODs) 1, 2, 4, and 5. Tumor growth was assessed weekly as an indicator of postoperative cellular immune response.

RESULTS

Compared with preoperative values, postoperative DTH skin reactions were significantly less for all PODs in groups III and IV (P < .05), on POD 1 and 4 in group II (P < .05) and POD 4 for group I (P < .05). Group IV showed significantly fewer DTH skin reactions for all PODs compared with groups I and II (P < .05) and all PODs except on day 2 compared with group III (P < .05). Tumor growth was significantly increased at postoperative week 2 (n = 3/17 mice) and 3 (n = 4/17 mice) in group IV, when compared with groups I and II (P < .05).

CONCLUSIONS

Cellular immunity is preserved after carbon dioxide pneumoperitoneum compared with extraperitoneal incisions and laparotomy as measured by DTH and the ability to reject an immunogenictumor.

Hypothermia in open and laparoscopic colorectal surgery

PURPOSE

Perioperative hypothermia has been shown to be an important determinant of outcome after open colorectal resections. The degree of hypothermia occurring with laparoscopic-assisted colorectal surgery is, however, unknown, and the effectiveness of standard warming measures is untested. This study was designed to assess hypothermia in open and laparoscopic-assisted colonic resections using a standardized warming protocol.

METHODS

A prospective, nonrandomized study was performed with temperature measurements recorded every ten minutes. Statistical analysis was based on repeated measures analysis of variance models with significance set at the conventional 95 percent (two tailed).

RESULTS

A total of 107 patients were entered into the trial; 68 had open and 39 had laparoscopic colectomies. The groups were well matched for age, weight, and duration of surgery, with a median operating time of 180 minutes in each group. The average drop in temperature from commencement of surgery to lowest point was 0.68 degrees C (standard deviation, 0.08) in the open group, compared with 0.53 degrees C (standard deviation, 0.06) in the laparoscopic group (P = 0.126).

CONCLUSIONS

Laparoscopic-assisted colorectal surgery is not associated with a higher incidence of perioperative hypothermia than open colorectal surgery using a standard warming regimen for both groups. On the basis of these results, standard temperature conservation is adequate, even for long, complex laparoscopic procedures.

A case-control study of postoperative pulmonary complications after laparoscopic and open cholecystectomy

Postoperative pulmonary complications (PPC) are common after upper abdominal surgery. The objective of this case-control study was to compare the incidence of PPC after laparoscopic cholecystectomy (LC) and open cholecystectomy (OC) within a tertiary care center. Patients were accrued from two sequential clinical trials that evaluated the role of incentive spirometry in the prevention of PPC after abdominal surgery. Included for study were patients with gallstones undergoing elective surgery who had an American Society of Anesthesiologists (ASA) classification < 3. All patients included in the study were encouraged to use an incentive spirometer at least 10 times each hour while awake. Patients with chronic bronchitis were excluded from study, as were patients who received other forms of physical therapy. OC was performed through either a transverse or an oblique incision. There was an equitable dispersion of putative risk factors for PPC between the groups at baseline. PPC were defined as clinical features consistent with collapse/consolidation, an otherwise unexplained temperature above 38 degrees C, plus either confirmatory chest radiology or positive sputum microbiology. The incidence of PPC was 2.7% (1/37) after LC and 17.2% (10/58) after OC (p < 0.05). It is concluded that PPC are less common after laparoscopic cholecystectomy than after open cholecystectomy.