The physiologic effects of pneumoperitoneum in the morbidly obese

Endoscopic peritoneal access and insufflation: natural orifice transluminal endoscopic surgery

BACKGROUND

Diagnostic transgastric endoscopic peritoneoscopy is a safe model for exploration of the peritoneum. Endoscopic insufflation of the peritoneal cavity has not been validated in humans. We report here our experience with pneumoperitoneum established endoscopically with a laparoscopic insufflator.

DESIGN

Pneumoperitoneum was established with a laparoscopic insufflator through the biopsy channel of the gastroscope. Intra-abdominal pressure was measured with a transfascial Veress needle and compared with endoscopic values. The gastrotomy was used in the creation of the gastric pouch.

PATIENTS

Twenty patients undergoing laparoscopic Roux-en-Y gastric bypass participated in the study. Ten had undergone no previous surgery, whereas the other 10 patients had a history of abdominal procedures.

INTERVENTIONS

Diagnostic transgastric endoscopic peritoneoscopy was performed through a gastrotomy created endoscopically without laparoscopic visualization.

MAIN OUTCOME MEASUREMENTS

Diagnostic findings, operating times, and clinical course were recorded.

RESULTS

The average time for transgastric access was 9.6 minutes. This did not vary in patients with previous surgery (P = .3). Endoscopic insufflation was successful in all patients. The mean endoscopic and laparoscopic pressures were 9.80 and 9.75 mm Hg, respectively (P = .9). In no patients were there limitations to visualization of the abdomen. Adhesions were noted in 80% and 10% of patients with and without a history of surgery, respectively (P = .005). There were no complications related to transgastric passage of the endoscope or exploration of the peritoneal cavity.

CONCLUSIONS

Although limited by the small sample size in this study, we believe that transgastric access may be considered as an alternative approach to peritoneal insufflation and provides a safe alternative for exploration of the abdomen. Endoscopic insufflation through the biopsy channel by using a laparoscopic insufflator seems to be an effective and safe method for establishing pneumoperitoneum.

Impact of the patient's body position on the intraabdominal workspace during laparoscopic surgery

Background

The effects of the patient’s body position on the intraabdominal workspace in laparoscopic surgery were analyzed.

Methods

The inflated volume of carbon dioxide was measured after insufflation to a preset pressure of 15 mmHg for 20 patients with a body mass index (BMI) greater than 35 kg/m². The patients were anesthetized with full muscle relaxation. The five positions were (1) table horizontal with the legs flat (supine position), (2) table in 20° reverse Trendelenburg with the legs flat, (3) table in 20° reverse Trendelenburg with the legs flexed 45° upward at the hips (beach chair position), (4) table horizontal with the legs flexed 45° upward at the hips, and (5) table in 20° Trendelenburg with the legs flat. The positions were performed in a random order, and the first position was repeated after the last measurement. Repeated measure analysis of variance was used to compare inflated volumes among the five positions.

Results

A significant difference in inflated volume was found between the five body positions (P = 0.042). Compared with the mean inflated volume for the supine position (3.22 ± 0.78 l), the mean inflated volume increased by 900 ml for the Trendelenburg position or when the legs were flexed at the hips, and decreased by 230 ml for the reverse Trendelenburg position.

Conclusions

The Trendelenburg position for lower abdominal surgery and reverse Trendelenburg with flexing of the legs at the hips for upper abdominal surgery effectively improved the workspace in obese patients, even with full muscle relaxation.

A new valve-less trocar for urologic laparoscopy: initial evaluation

INTRODUCTION

Laparoscopic trocars typically maintain pneumoperitoneum using trap door valves and silicone seals. However, valves and seals hinder passage of instruments, cause lens smudging, trap specimens and needles being removed from the abdominal cavity, and lose their seal with repeated instrument exchange.

AIM

The aim of the present study was to evaluate the feasibility of a newly designed valve-less trocar.

METHODS

The valve-less trocar system creates a curtain of forced gas to maintain pneumoperitoneum. A separate unit filters smoke and recirculates captured escaping gas. The valve-less trocar was trialed in consecutive laparoscopic renal procedures of a single surgeon. Perioperative parameters and outcomes were collected and analyzed. The system's safety, advantages, and disadvantages were evaluated. Insufflation gas usage, elimination, and absorption were also measured.

RESULTS

Twenty-five patients underwent laparoscopic renal procedures using the valve-less trocar system. The procedures included laparoscopic partial, radical, and donor nephrectomy. The mean patient age was 58.26 years. The mean operative time was 125 minutes and the mean drop in Hb for the cohort was 2.34 g/dL (range 0.4-5.4). Two patients developed subcutaneous emphysema and of the two patients, one developed clinically insignificant pneumomediastinum postoperatively. There were no postoperative complications. The surgeon noted that the use of a valve-less trocar decreased smudging of laparoscopes, expeditiously evacuated smoke during cauterization leading to improved visualization, maintained pneumoperitoneum even while suctioning, and resulted in easy extraction of specimens and needles. It was noted that insufflation gas consumption was low and CO(2) elimination was not impaired.

CONCLUSION

Use of a valve-less trocar is safe. Decreased laparoscope smudging may translate into decreased operative times and reduced gas consumption may equate to cost savings. Additionally, its use brings several advantages and convenience to the operating surgeon. However, the system should be compared with conventional trocars prospectively to demonstrate clinical and economic benefit.

Perioperative management of patients with cytoreductive surgery for peritoneal carcinomatosis

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) has become an important tool in the management of patients with peritoneal malignancies. It is a complex surgical procedure with significant fluid loss during debulking leading to relevant pathophysiological alterations and therefore a challenge for anesthesiologists and critical care physicians. This review summarizes perioperative changes in hemodynamics, oxygen supply, coagulation, hematopoetic parameters and fluid status during cytoreductive surgery and HIPEC and how to deal with these pathophysiological alterations.

Development of atelectasis and arterial to end-tidal PCO2-difference in a porcine model of pneumoperitoneum

BACKGROUND

Intraperitoneal insufflation of carbon dioxide (CO2) may promote collapse of dependent lung regions. The present study was undertaken to study the effects of CO2-pneumoperitoneum (CO2-PP) on atelectasis formation, arterial oxygenation, and arterial to end-tidal PCO2-gradient (Pa-E'(CO2)).

METHODS

Fifteen anaesthetized pigs [mean body weight 28 (SD 2) kg] were studied. Spiral computed tomography (CT) scans were obtained for analysis of lung tissue density. In Group 1 (n=5) mechanical ventilation (V(T)=10 ml kg (-1), FI(O2)=0.5) was applied, in Group 2 (n=5) FI(O2) was increased for 30 min to 1.0 and in Group 3 (n=5) negative airway pressure was applied for 20 s in order to enhance development of atelectasis. Cardiopulmonary and CT data were obtained before, 10, and 90 min after induction of CO2-PP at an abdominal pressure of 12 mmHg.

RESULTS

Before CO2-PP, in Group 1 non-aerated tissue on CT scans was 1 (1)%, in Group 2 3 (2)% (P<0.05, compared with Group 1), and in Group 3 7 (3)% (P<0.05, compared with Group 1 and Group 2). CO2-PP significantly increased atelectasis in all groups. PaO2/FI(O2) fell and venous admixture ('shunt') increased in proportion to atelectasis during anaesthesia but CO2-PP had a varying effect on PaO2/FI(O2) and shunt. Thus, no correlation was seen between atelectasis and PaO2/FI(O2) or shunt when all data before and during CO2-PP were pooled. Pa-E'(CO2), on the other hand correlated strongly with the amount of atelectasis (r2=0.92).

CONCLUSIONS

Development of atelectasis during anaesthesia and PP may be estimated by an increased Pa-E'(CO2).

[Hydroxyethyl starch to protect renal function in laparoscopic surgery]

OBJECTIVE

To evaluate the effect of prehydration with hydroxyethyl starch 130/0.4 (Voluven) compared to lactated Ringer solution in laparoscopic cholecystectomy.

PATIENTS AND METHODS

We performed a randomized single-blind clinical trial on patients classified as ASA 1 and 2. The exclusion criteria were hypertension, kidney failure, treatment with diuretics or other antihypertensive drugs, diabetes, and use of nonsteroidal anti-inflammatory drugs. Balanced general anesthesia with remifentanil and sevoflurane was used. The total volume of administered fluids (including prehydration) was 2 mL x kg(-1) x h(-1) fasting plus 5 mL x kg(-1) x h(-1) during surgery. Group 1 was prehydrated 30 minutes before surgery with 500 mL of lactated Ringer solution in group 1; in group 2 the same quantity of Voluven was used. Ringer solution was used in both groups to provide additional fluids. Blood pressure was kept within 20% above or below baseline values. Standard anesthetic monitoring was performed. Intraoperative diuresis and creatinine clearance were recorded. The groups were compared using the t test; a P value of 05 or less was considered significant.

RESULTS

Twenty-nine patients were enrolled in the study. Diuresis and creatinine clearance were significantly higher in the group that received prehydration with Voluven. The mean (SD) creatinine clearance rate was 176.44 (1433) mL x min(-1) in group 1 and 61.90 (6.6) mL x min(-1) in group 2 (P = .036). The mean volume of urine excreted was 1.71 (0.06) mL x kg(-1) x h(-1) in group 1 and 0.47 (0.02) mL x kg(-1) x h(-1) in group 2 (P = .017).

CONCLUSION

Prehydration with Voluven can be an effective measure for protecting renal function against the adverse effects of pneumoperitoneum in laparoscopic surgery.

The impact of body mass index on laparoscopic cholecystectomy in Taiwan: an oriental experience

BACKGROUND/PURPOSE

The outcome analysis of obese patients undergoing laparoscopic cholecystectomy (LC) in Asia-Pacific countries is rarely reported. This study examined associations between body mass index (BMI) and clinical outcomes of elective LC in Taiwan.

METHODS

A total of 627 patients with gallbladder disease due to gallstones undergoing LC were divided into three groups based on BMI: <25.0 kg/m2 (normal, NO; n = 310), 25.0-29.9 kg/m2 (overweight, OW; n = 252), and >30 kg/m2 (obese, OB; n = 65).

RESULTS

Both overweight and obesity were not associated with conversion and complication rates. The conversion rates of the three groups were 5.5 (NO), 6.0 (OW), and 4.6% (OB), and the complication rates were 3.2 (NO), 2.4% (OW), and 4.6% (OB), respectively. However, overweight and obesity were related to a trend toward longer operating time (NO 67.4 +/- 31.8; OW 77.8 +/- 35.6; OB 79.0 +/- 37.9 min) (P trend <0.001). One death (BMI 40.6 kg/m2) was due to septic complications. In the multivariable logistic analysis, only acute cholecystitis, but not BMI, was a predictor for conversion and complications.

CONCLUSIONS

Based on these results, it appears that BMI was not associated with clinical outcomes and that LC is a safe procedure in obese patients with uncomplicated gallstone disease in Taiwan.

Carbon dioxide for gut distension during digestive endoscopy: technique and practice survey

AIM

To assess the adoption of Carbon dioxide (CO2) insufflation by endoscopists from various European countries, and its determinants.

METHODS

A survey was distributed to 580 endoscopists attending a live course on digestive endoscopy.

RESULTS

The response rate was 24.5%. Fewer than half the respondents (66/142, 46.5%) were aware of the fact that room air can be replaced by CO2 for gut distension during endoscopy, and 4.2% of respondents were actually using CO2 as the insufflation agent. Endoscopists aware of the possibility of CO2 insufflation mentioned technical difficulties in implementing the system and the absence of significant advantages of CO2 in comparison with room air as barriers to adoption in daily practice (84% and 49% of answers, respectively; two answers were permitted for this item).

CONCLUSION

Based on this survey, adoption of CO2 insufflation during endoscopy seems to remain relatively exceptional. A majority of endoscopists were not aware of this possibility, while others were not aware of recent technical developments that facilitate CO2 implementation in an endoscopy suite.

Beneficial effects of high positive end-expiratory pressure in lung respiratory mechanics during laparoscopic surgery

BACKGROUND

The effect of neuromuscular blockade (NMB) and positive end-expiratory pressure (PEEP) on the elastic properties of the respiratory system during pneumoperitoneum (PnP) remains a controversial subject. The main objective of the present study was to evaluate the effects of NMB and PEEP on respiratory mechanics.

METHODS

We performed a dynamic analysis of respiratory mechanics in patients subjected to PnP. Twenty-one patients underwent cholecystectomy videolaparoscopy and total intravenous anesthesia. The respiratory system resistance (R(RS)), pulmonary elastance (E(P)), chest wall elastance (E(CW)), and respiratory system elastance (E(RS)) were computed via the least squares fit technique using an equation describing the motion of the respiratory system, which uses primary signs such as airway pressure, tidal volume, air flow, and esophageal pressures. Measurements were taken after tracheal intubation, PnP, NMB, establishment of PEEP (10 cmH2O), and PEEP withdrawal [zero end-expiratory pressure (ZEEP)].

RESULTS

PnP significantly increased E(RS) by 27%; both E(P) and E(CW) increased 21.3 and 64.1%, respectively (P < 0.001). NMB did not alter the respiratory mechanic properties. Setting PEEP reduced E(RS) by 8.6% (P < 0.05), with a reduction of 10.9% in E(P) (P < 0.01) and a significant decline of 15.7% in R(RS) (P < 0.05). These transitory changes in elastance disappeared after ZEEP.

CONCLUSIONS

We concluded that the 10 cmH2O of PEEP attenuates the effects of PnP in respiratory mechanics, lowering R(RS), E(P), and E(RS). These effects may be useful in the ventilatory approach for patients experiencing a non-physiological increase in IAP owing to PnP in laparoscopic procedures.

High flow insufflation for the maintenance of the pneumoperitoneum during bariatric surgery

Minimally invasive bariatric procedures next to becoming more and more popular have established a new field of applications for carbon dioxide (CO2) insufflators. In laparoscopic bariatric procedures, gas is used to insufflate the peritoneal cavity and increase the intra-abdominal pressure up to 15 mm Hg for optimal exposure and a suitable operating field. The increased intra-abdominal pressure during pneumoperitoneum can reduce femoral venous flow, intra-operative urine output, portal venous flow, respiratory compliance,and cardiac output. However, clinical complications related to these effects are rare. Yet, surgeons should be constantly aware that the duration of an operation is an important factor in reducing the patient's exposure to CO2 pneumoperitoneum and its adverse effects. The optimized performance of the bariatric high flow insufflator allows reaching stable abdominal pressure conditions quicker and at a higher level than a common insufflator. Therefore, high flow insufflators offer great advantages in maintaining intra-abdominal pressure and temperature in comparison to conventional insufflators and thus enhance laparoscopic bariatric surgery by potentially reducing the operating time and the undesirable effects of CO2 pneumoperitoneum.

Perioperative renal protection

Acute kidney injury (AKI) is a significant cause of perioperative patient morbidity and mortality. The definition of AKI has recently changed and further research is underway to identify clinically relevant biomarkers to aid in the diagnosis of the syndrome. AKI is often multi-factorial in origin and patients with certain preoperative risk factors are at elevated risk of perioperative AKI. An anesthesiologist's main objective for perioperative renal protection is prevention by maintenance of euvolemia, preservation of adequate renal perfusion, and avoidance of nephrotoxins. This review will address the definition and diagnosis of AKI, identify patients at risk of AKI, and critically appraise management options for perioperative renal protection.

Peri-operative anaesthetic management of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is a long and complex procedure with significant blood and fluid loss during debulking and important pathophysiological alterations during the HIPEC phase. We performed a retrospective analysis of 78 consecutive patients undergoing cytoreductive surgery with HIPEC at a university hospital. Our data demonstrate large intra-operative fluid turnover, with 51% of patients requiring a blood transfusion. During HIPEC, airway pressure and central venous pressure increased with a lower oxygenation ratio as a result of increased intra-abdominal pressure with the closed abdomen technique. As a consequence of the raised body temperature, heart rate, end tidal carbon dioxide and arterial lactate levels increased with a slight metabolic acidosis. Peri-operative analysis of routine clotting parameters revealed disturbances of the coagulation status. For pain management, 72% of patients received supplementary thoracic epidural analgesia with consequential peri-operative opioid sparing and a reduced duration of postoperative ventilation.

Laparoscopic surgery is associated with a lower incidence of venous thromboembolism compared with open surgery

BACKGROUND

Although laparoscopy now plays a major role in most general surgical procedures, little is known about the relative risk of venous thromboembolism (VTE) after laparoscopic compared with open procedures.

OBJECTIVE

To compare the incidence of VTE after laparoscopic and open surgery over a 5-year period.

PATIENTS AND INTERVENTIONS

Clinical data of patients who underwent open or laparoscopic appendectomy, cholecystectomy, antireflux surgery, and gastric bypass between 2002 and 2006 were obtained from the University HealthSystem Consortium Clinical Database. The principal outcome measure was the incidence of venous thrombosis or pulmonary embolism occurring during the initial hospitalization after laparoscopic and open surgery.

RESULTS

During the 60-month period, a total of 138,595 patients underwent 1 of the 4 selected procedures. Overall, the incidence of VTE was significantly higher in open cases (271 of 46,105, 0.59%) compared with laparoscopic cases (259 of 92,490, 0.28%, P < 0.01). Our finding persists even when the groups were stratified according to level of severity of illness. The odds ratio (OR) for VTE in open procedures compared with laparoscopic procedures was 1.8 [95% confidence interval (CI) 1.3-2.5]. On subset analysis of individual procedures, patients with minor/moderate severity of illness level who underwent open cholecystectomy, antireflux surgery, and gastric bypass had a greater risk for developing perioperative VTE than patients who underwent laparoscopic cholecystectomy (OR: 2.0; 95% CI: 1.2-3.3; P < 0.01), antireflux surgery (OR: 24.7; 95% CI: 2.6-580.9; P < 0.01), and gastric bypass (OR: 3.4; 95% CI: 1.8-6.5; P < 0.01).

CONCLUSIONS

Within the context of this large administrative clinical data set, the frequency of perioperative VTE is lower after laparoscopic compared with open surgery. The findings of this study can provide a basis to help surgeons estimate the risk of VTE and implement appropriate prophylaxis for patients undergoing laparoscopic surgical procedures.

Acute renal failure after prolonged pneumoperitoneum in robot-assisted prostatectomy: a rare complication report

Robot-assisted surgery has been used widely in urological surgery since 2000. In Taiwan, robotic surgery started in 2004 and progress has been ongoing since this time. Herein we report a case of acute renal failure post robot-assisted radical prostatectomy. The patient received postoperative hemodialysis and intensive care. The renal function recovered to a serum creatinine level of 2.0 mg/dl 2 months after surgical intervention. The renal function was still normal and the PSA level was nadir after one-year follow-up. The outcome is encouraging from the point of view of oncology. To our knowledge, this is the first report of postoperative acute renal failure in robotic surgery.

Targeting individual hemodynamics to maintain renal perfusion during pneumoperitoneum in a porcine model

BACKGROUND

Although aggressive fluid hydration prevents a decrease in renal cortical perfusion (RCP) during laparoscopic donor nephrectomy, excess fluid is deleterious. We assessed whether goal-directed fluid administration, based on hemodynamic measures, would maintain RCP during pneumoperitoneum with less fluid loading.

METHODS

In a pilot study of 7 pigs, goal-directed fluid administration was guided by monitoring of stroke volume (SV) by esophageal Doppler measurement. During 15 mmHg CO(2) pneumoperitoneum, a bolus of 5 mL/kg 0.9% NaCl was given when SV decreased to 90% of baseline. Next, 18 pigs were randomized into 3 groups: low fluid (5 mL/kg per hour), high fluid (25 mL/kg per hour) and goal directed. Urine output, heart rate, mean arterial pressure, cardiac output, SV, and RCP were recorded every 15 minutes.

RESULTS

Pilot data revealed mean RCP (mL/min per 100 g) was maintained (40 vs 39) during pneumoperitoneum using goal-directed therapy. In the randomized study, RCP was decreased in the low fluid group (43 vs 29; P= .02), but maintained in the high (46 vs 40) and goal-directed (42 vs 39) groups. Mean fluid administered in the goal-directed group during pneumoperitoneum was 10 mL/kg and only 3 of 6 of pigs required boluses. Urine output was decreased in all 3 groups.

CONCLUSION

A goal-directed strategy during pneumoperitoneum allows for tailored fluid administration and maintains RCP with lower volumes of intravenous fluid.

Physiologic changes during helium insufflation in high-risk patients during laparoscopic renal procedures

OBJECTIVES

To assess the efficacy and safety of helium as an insufflant for transabdominal laparoscopic renal surgery.

METHODS

The charts of all patients undergoing laparoscopic renal surgery with helium insufflation by a single physician between May 2003 and April 2006 were reviewed. Ventilatory parameters and postoperative recovery were reviewed.

RESULTS

Ten patients underwent laparoscopic renal surgery with helium. These patients had a mean age of 64 years and suffered from a variety of comorbid conditions, including chronic obstructive pulmonary disease (5), congestive heart failure (1), chronic hypoxia from an intrapulmonary shunt (1), malignant hyperthermia (1), and chronic hypoxia from multiple pulmonary infarcts (1). All patients tolerated helium pneumoperitoneum, with mean O2 saturation of 98.6% +/- 0.6%, end-tidal CO2 31.4 +/- 1.7 mm Hg, respiratory rate 9.3 +/- 0.7 breaths per minute, tidal volumes 598.2 +/- 38.0 mL, and peak airway pressures 26.0 +/- 1.2 cm H2O. One patient developed an end-tidal CO2 of greater than 45 mm Hg. Mean operative time was 146.8 +/- 59 minutes, and estimated blood loss was 280.1 +/- 334 mL. Postoperatively 3 patients required continued maintenance of the endotracheal tube, although none required intubation longer than 22 hours. Five patients had critical care monitoring (1.7 +/- 2.9 days on average).

CONCLUSIONS

Helium can be used safely as an insufflant during laparoscopic renal surgery. Patients who may benefit are those with potential difficulty in clearing CO2 gas from their bloodstream or those who rely on sensitive monitoring of end-tidal CO2 to manage comorbid pathology.

A randomized controlled study evaluating the effects of the temperature of insufflated CO2 on core body temperature and blood gases (an experimental study)

BACKGROUND

Heated carbon dioxide (CO2) was used for pneumoperitoneum (Pp) to prevent hypothermia. This study aimed to investigate the relationship between the temperature of the insufflated CO2 and blood gases together with the core body temperature (CBT).

METHODS

A prospective controlled study was performed with 24 pigs weighing approximately 20 kg randomized into four groups of 6 pigs each. A pneumoperitoneum at 12 mmHg of pressure was applied for 60 min with the pig under general anesthesia. The CO2)temperature was 22 degrees C in group 1, 37 degrees C in group 2, and 7 degrees C in group 3. In the "sham" group, pneumoperitoneum was not applied. Arterial blood pH and partial pressure of CO2 (PaCO2) were analyzed before insufflation, every 15 min during the pneumoperitoneum, and 15 min after the desufflation. The CBT was recorded before the insufflation, every 20 min during pneumoperitoneum, and 20 min after the desufflation. Blood gas analyses and CBT records for the "sham" group were performed at the same intervals.

RESULTS

Arterial blood pH gradually decreased during pneumoperitoneum. At the 60th minute of pneumoperitoneum, a minimum decrease in arterial blood pH (0.04; p = 0.027) and a minimum increase in PaCO2 (3.67; p = 0.027) were recorded in group 3, whereas a maximum decrease in arterial blood pH (0.18; p = 0.027) and a maximum increase in PaCO2 (17.17; p = 0.027) were recorded in group 2. There was a significant negative correlation between PaCO2 and arterial blood pH in all the groups (r = -0.993; p < 0.01). The mean values of CBT decreases were statistically significant in all the groups: group 1 (p = 0.023), group 2 (p = 0.026), group 3 (p = 0.026), and "sham" group (p = 0.024).

CONCLUSIONS

The changes in PaCO2 were directly proportional and the changes in pH contrarily proportional to the temperature of the insufflated CO2. Significant differences in CBT decreases were found between the groups receiving heated gas and room temperature gas and the groups receiving heated gas and gas below room temperature.

Pulmonary considerations in obesity and the bariatric surgical patient

Severe obesity can be associated with significant alterations in normal cardiopulmonary physiology. The pathophysiologic effects of obesity on a patient's pulmonary function are multiple and complex. The impact of obesity on morbidity and mortality are often underestimated. Bariatric surgery has been shown to be the most effective modality of reliable and durable treatment for severe obesity. Surgical weight loss improves and, in most cases, completely resolves the pulmonary health problems associated with obesity.

Laparoscopic spray application of fibrin sealant effects on hemodynamics and spray efficiency at various application pressures and distances

BACKGROUND

Laparoscopic resections of parenchymal organs are increasingly performed. However, little is known about the effects of laparoscopic fibrin sealant spray applications on intraabdominal pressure (IAP) and hemodynamics.

METHODS

Cardiac and pulmonary monitoring was performed via two central venous pressure lines in the thoracic and abdominal vena cava, a pulmonary artery catheter, and a peripheral artery line. Air was sprayed into the abdomen at pressures of 2, 3, and 4 bar for 30 s. According to the group, a valve on a trocar was open or closed. To optimize fibrin sealant application, the sealant was sprayed at three different application pressures (2, 2.5, and 3 bar) and distances (2, 3.5, and 5 cm).

RESULTS

All spray simulations caused a significant increase in the IAP. During the first 10 s of spraying, the IAP increase was 5 mmHg or less, but rose rapidly during the last 20 s of spraying. The IAP increase resulted in decreased pulmonary compliance. Pulmonary resistance and the central venous pressures of both the thoracic and abdominal vena cava increased. At application pressures of 3 and 4 bar, the IAP increase was greater than 2 bar of pressure, reaching IAP values exceeding 35 mmHg. Spray mist formation was primarily dependent on application pressure, whereas clot formation and surface coverage depended on both application pressure and distance. The best results were achieved with an application pressure of 2.5 bar and a distance of 5 cm from the surface.

CONCLUSIONS

This study shows that fibrin sealants can be used safely in laparoscopic procedures. Keeping the spray periods short and allowing air to escape from the abdomen can minimize the IAP increase. According to our results, a laparoscopic spray application of fibrin sealant should start with an insufflation pressure of 10 mmHg, an application pressure of 2.5 bar, and an application distance of 5 cm with a valve on the trocar left open.

A reliable method for monitoring intraabdominal pressure during natural orifice translumenal endoscopic surgery

BACKGROUND

Natural orifice translumenal endoscopic surgery (NOTES) provides surgical access to the peritoneal cavity without skin incisions. The NOTES procedure requires pneumoperitoneum for visualization and manipulation of abdominal organs, similar to laparoscopy. Accurate measurement of the pneumoperitoneum pressure is essential to avoid potentially deleterious effects of intraabdominal compartment syndrome. A reliable method for monitoring pneumoperitoneum pressures during NOTES has not been identified. This study evaluated several methods of monitoring intraabdominal pressures with a standard gastroscope during NOTES.

METHODS

Four female pigs (25 kg) were sedated, and a single-channel gastroscope was passed transgastrically into the peritoneal cavity. Pneumoperitoneum was achieved via a pressure insufflator through a percutaneous, intraperitoneal 14-gauge catheter. Three other pressures were recorded via separate catheters. First, a 14-gauge percutaneous catheter passed intraperitoneally measured true intraabdominal pressure. Second, a 14-gauge tube attached to the endoscope was used to measure endoscope tip pressure. The third pressure transducer was connected directly to the accessory channel of the endoscope. The abdomen was insufflated to a range of pressures (10-30 mmHg), and simultaneous pressures were recorded from all three pressure sensors.

RESULTS

Pressure correlation curves were developed for all animals across all intraperitoneal pressures (mean error, -4.25 to -1 mmHg). Endoscope tip pressures correlated with biopsy channel pressures (R2 = 0.99). Biopsy channel and endoscope tip pressures fit a least-squares linear model to predict actual intraabdominal pressure (R = 0.99 for both). Both scope tip and biopsy channel port pressures were strongly correlative with true intraabdominal pressures (R2 = 0.98 and R2 = 0.99, respectively).

CONCLUSION

This study demonstrates that monitoring pressure through an endoscope is reliable and predictive of true intraabdominal pressure. Gastroscope pressure monitoring is a useful adjunct to NOTES. Future NOTES procedures should incorporate continuous intraabdominal pressure monitoring to avoid the potentially deleterious effects of pneumoperitoneum during NOTES. This can be achieved by the integration of pressure-monitoring capabilities into gastroscopes.

Effect of pneumoperitoneum on renal perfusion and function: a systematic review

BACKGROUND

The precise physiologic consequences of insufflating carbon dioxide into the abdominal cavity during laparoscopy are not yet fully understood. This systematic review aimed to investigate whether pneumoperitoneum results in decreased renal blood flow (RBF) or renal function.

METHODS

A literature search was conducted electronically using Medline, Embase, and the Cochrane libraries on 1 July 2005. Various combinations of the medical subject headings--renal blood flow, pneumoperitoneum, renal function, and laparoscopy--were searched in all three databases. Reference lists from articles fulfilling the search criteria were used to identify additional articles.

RESULTS

The literature search retrieved 20 articles concerning RBF and 25 articles concerning renal function during pneumoperitoneum. It was found that 17 of the 20 studies identified a decrease in RBF, and 20 of the 25 studies identified a decrease in renal function during pneumoperitoneum.

CONCLUSION

There appears to be sufficient evidence to conclude that both renal function and RBF are decreased during pneumoperitoneum. The magnitude of the decrease is dependent on factors such as preoperative renal function, level of hydration, level of pneumoperitoneum, patient positioning, and duration of pneumoperitoneum.

Perioperative care of patients undergoing bariatric surgery

The epidemic of obesity in developed countries has resulted in patients with extreme (class III) obesity undergoing the full breadth of medical and surgical procedures. The popularity of bariatric surgery in the treatment of extreme obesity has raised awareness of the unique considerations in the care of this patient population. Minimizing the risk of perioperative complications that contribute to morbidity and mortality requires input from several clinical disciplines and begins with the preoperative assessment of the patient. Airway management, intravenous fluid administration, physiologic responses to pneumoperitoneum during laparoscopic procedures, and the risk of thrombotic complications and peripheral nerve injuries in extremely obese patients are among the factors that present special intraoperative challenges that affect postoperative recovery of the bariatric patient. Early recognition of perioperative complications and education of the patient regarding postoperative issues, including nutrition and vitamin supplementation therapy, can improve patient outcomes. A suitable physical environment and appropriate nursing and dietetic support provide a safe and dignified hospital experience. This article reviews the multidisciplinary management of extremely obese patients who undergo bariatric surgery at the Mayo Clinic.

Challenges of laparoscopic colectomy in the obese patient: a review

BACKGROUND

Perioperative care of clinically severely obese patients presents numerous unique challenges. These patients have distinctive issues with regard to cardiovascular, pulmonary, and thromboembolic complications. In addition, hospital equipment must be able to accommodate the body habitus of this population.

METHODS

A Medline search using the terms "morbid obesity," "colon resection," "obesity comorbidities," "laparoscopic colectomy," "perioperative challenges," and "risk factors" was performed for English-language articles. Further references were obtained through cross-referencing the bibliography cited in each publication.

RESULTS

The authors discussed the most relevant challenges surgeons encounter in the perioperative setting when treating obese patients.

COMMENTS

The management of the morbidly obese patient requires meticulous preoperative, intraoperative, and postoperative care. Colorectal surgeons should be familiar with obesity-related problems when treating colorectal disease processes in this patient population. The associated comorbid illnesses in this population, as well as the technical difficulties regularly posed by them, make laparoscopic colectomy a more challenging procedure than normally encountered in the nonobese patient population.

Critical care of the bariatric patient

OBJECTIVE

To synthesize the current literature on care of obese, critically ill, and bariatric surgical patients.

DATA SOURCE

A MEDLINE/PubMed search from 1966 to August 2005 was conducted using the search terms obesity, bariatric surgery, and critical illness, and a search of the Cochrane Library was also conducted.

DATA EXTRACTION AND SYNTHESIS

An increase in both the prevalence of obesity and the number of bariatric procedures performed has resulted in an increased number of obese and, specifically, bariatric surgical patients who require intensive care unit care. Obesity is a chronic inflammatory state with resultant effects on immune, metabolic, respiratory, cardiovascular, gastrointestinal, hematologic, and renal function. Principles of care of the critically ill obese patient are reviewed and then applied to critically ill bariatric surgical patients. Pharmacotherapy, vascular access, and the presentation and management of both pressure-induced rhabdomyolysis and anastomotic failure after bariatric surgery are also reviewed.

CONCLUSIONS

Obesity causes a range of pathologic effects on all major organ systems. Knowledge of these effects and issues specific to the intensive care unit care of bariatric patients can help to predict and manage complications in this population.

Hemodynamic and Respiratory Effects of Pediatric Urological Retroperitoneal Laparoscopic Surgery: A Prospective Study

PURPOSE

Our understanding of the effects of retroperitoneal CO(2) insufflation on cardiopulmonary variables in children remains limited. This study was designed to investigate prospectively the effect of CO(2) insufflation in a pediatric population undergoing retroperitoneal laparoscopic surgery.

MATERIALS AND METHODS

We prospectively evaluated a consecutive series of patients enrolled between July 2003 and August 2004. Anesthesia was administered following a standardized protocol. Data collection included respiratory rate, PAP, O(2) saturation, ETCO(2), HR, MAP, electrocardiogram and insufflation pressure. All variables were recorded before, during and after CO(2) insufflation at regular intervals of 1 to 2 minutes, with up to 23 measurements recorded for each period.

RESULTS

A total of 18 participants were recruited. Mean +/- SD for age and weight were 79.4 +/- 53.2 months and 26.7 +/- 15.5 kg, respectively. Mean retroperitoneal CO(2) insufflation pressure was kept at 12 mm Hg. Significant differences (p <0.05) in average ETCO(2), PAP and MAP were noted after CO(2) insufflation compared to baseline (pre-pneumoretroperitoneum) values. HR and temperature did not change. At completion of the laparoscopic intervention physiological variables exhibited a trend to return to baseline values.

CONCLUSIONS

This prospective study documents significant changes in systemic hemodynamic variables that seem to be directly associated with the insufflation of CO(2) during pediatric retroperitoneal laparoscopic surgery. This ongoing evaluation confirms the effect of laparoscopic urological surgery and CO(2) insufflation on cardiopulmonary function in children.

Electrical impedance tomography: changes in distribution of pulmonary ventilation during laparoscopic surgery in a porcine model

BACKGROUND

Because of the creation of a pneumoperitoneum, impairment of ventilation is a common side-effect during laparoscopic surgery. Electrical impedance tomography (EIT) is a method with the potential for becoming a tool to quantify these alterations during surgery. We have studied the change of regional ventilation during and after laparoscopic surgery with EIT and compared the diagnostic findings with computed tomography (CT) scans in a porcine study.

MATERIALS AND METHODS

After approval by the local animal ethics committee, six pigs were included in the study. Two laparoscopic operations were performed [colon resection (n=3) and fundoplicatio (n=3)]. The EIT measurements (6th parasternal intercostal space) were continuously recorded by an EIT prototype (EIT Evaluation Kit, Dräger Medical, Lübeck, Germany). To verify ventilatory alterations detected by EIT, a CT scan was performed postoperatively.

RESULTS

Ventilation with defined tidal volumes was significantly correlated to EIT measurements (r2=0.99). After creation of the pneumoperitoneum, lung compliance typically decreased, which agreed well with an alteration of the distribution of pulmonary ventilation measured by EIT. Elevation of positive end-inspiratory pressure reopened non-aerated lung areas and showed a recovery of the regional ventilation measured by EIT. Additionally, we could detect pulmonary complications by EIT monitoring as verified by CT scans postoperatively.

CONCLUSION

EIT monitoring can be used as a continuous non-invasive intraoperative monitor of ventilation to detect regional changes of ventilation and pulmonary complications during laparoscopic surgery. These EIT findings indicate that surgeons and anesthetists may eventually be able to optimize ventilation directly in the operating theatre.

Abdominal insufflation with CO2 causes peritoneal acidosis independent of systemic pH

We have shown that the inflammation-attenuating effects of CO(2) pneumoperitoneum during laparoscopy are not due to changes in systemic pH. However, acidification of peritoneal macrophages in an in vitro CO(2) environment has been shown to reduce LPS-mediated cytokine release. We tested the hypothesis that the peritoneum is locally acidotic during abdominal insufflation with CO(2)--even when systemic pH is corrected. Rats (n = 20) were anesthetized and randomized into two groups: continued spontaneous ventilation (SV) or intubation and mechanical ventilation (MV). All animals were then subjected to abdominal insufflation with CO(2). Mean arterial pH among SV rats decreased significantly from baseline after 15 and 30 minutes of CO(2) pneumoperitoneum (7.329 --> 7.210 --> 7.191, P < 0.05), while arterial pH among MV rats remained relatively constant (7.388 --> 7.245 --> 7.316, P = NS). In contrast, peritoneal pH dropped significantly from baseline and remained low for both groups during CO(2) abdominal insufflation (SV 6.74 --> 6.41 --> 6.40, P < 0.05; MV 6.94 --> 6.45 --> 6.45, P < 0.05). In a second experiment, rats (n = 10) were randomized to receive abdominal insufflation with either CO(2) or helium. Abdominal insufflation with helium did not significantly affect peritoneal pH (7.10 --> 7.02 --> 6.95, P = NS), and the decrease in pH among CO(2)-insufflated animals was significant compared with helium-insufflated animals (P < 0.05). Peritoneal pH returned to baseline levels in all groups within 15 minutes of desufflation in both experiments. A significant local peritoneal acidosis occurs during laparoscopy which is specifically attributable to the use of CO(2) and which is independent of systemic pH. These data provide additional evidence that localized peritoneal acidosis is central to the mechanism of CO(2)-mediated attenuation of the inflammatory response following laparoscopic surgery.