Effect of laparoscopic antireflux surgery upon renal blood flow

Motion control skill assessment based on kinematic analysis of robotic end-effector movements

BACKGROUND

The performance of robotic end-effector movements can reflect the user's operation skill difference in robot-assisted minimally invasive surgery. This study quantified the trade-off of speed-accuracy-stability by kinematic analysis of robotic end-effector movements to assess the motion control skill of users with different levels of experience.

METHODS

Using 'MicroHand S' system, 10 experts, 10 residents and 10 novices performed single-hand test and bimanual coordination test. Eight metrics based on the movements of robotic end-effectors were applied to evaluate the users' performance.

RESULTS

In the single-hand test, experts outperformed other groups except for movement speed; in the bimanual coordination test, experts also performed better except for movement time and movement speed. No statistically significant difference in performance was found between residents and novices.

CONCLUSIONS

The kinematic differences obtained from the movements of robotic end-effectors can be applied to assess the motion control skill of users with different skill levels.

Carbon dioxide insufflation causes upper urinary tract injury in the early period of an experimental vesicoureteral reflux model

PURPOSE

Ureteral reimplantation via pneumovesicum is a new aspect of vesicoureteral reflux management. We aimed to determine the effects of carbon dioxide (CO2) insufflation on the upper urinary tract in an experimental model.

MATERIALS AND METHODS

Thirty New Zealand rabbits were allocated into five groups of six rabbits each. Right ureters were cannulated for CO2 insufflation in four groups. The pressures and durations of CO2 insufflation in the respective groups were as follows: Group A (10 mm Hg, 2 h); B (12 mm Hg, 2 h); C (10 mm Hg, 4 h); and D (12 mm Hg, 4 h) and control (E). Blood gas analysis, urea and creatinine levels were measured from renal veins and aorta. Histopathological evaluation of the renal parenchyma and ureters was scored.

RESULTS

Significant histopathological changes were detected in the ipsilateral ureter and renal parenchyma exposed to CO2 insufflation, predominantly observed in groups insufflated for longer durations, p < 0.05. Blood gases drawn separately from renal veins were significantly more acidotic, and serum urea and creatinine levels were increased in all the groups, p < 0.05.

CONCLUSIONS

CO2 causes significant histopathological and biochemical changes in the early period. Long-term results are required to determine whether permanent renal injury occurs.

A prospective assessment of renal oxygenation in children undergoing laparoscopy using near-infrared spectroscopy

BACKGROUND

This study was designed to determine whether a decrease in renal oxygenation occurs during CO2 pneumoperitoneum in children with normal renal function undergoing laparoscopy.

METHODS

Near infrared spectroscopy (NIRS) probes were applied to both the lateral flank (T10-L2) and lateral cerebral area of all patients with normal renal function undergoing a laparoscopic procedure. Information was recorded in 5-s intervals for 15-min before, during, and for 15-min after pneumoperitoneum insufflation and desufflation. Simultaneously, additional hemodynamic parameters (arterial saturation, mean arterial pressure, end tidal CO2, and urine output) were recorded every 5-min. Pneumoperitoneum pressures used were: 0-1 month old, <6 mmHg; 2-12 months old, <8 mmHg; 1-2 years old, <10 mmHg, and 2-8 years old, <12 mmHg. The lowest possible pressure was used to obtain adequate vision.

RESULTS

Twenty-nine patients were enrolled in the study. Renal regional oxygen saturation (rSO2) did not decrease significantly between baseline (preinsufflation), insufflation, and desufflation of the pneumoperitoneum (p = 0.343). Meta-analysis of this data demonstrated a pooled weighted difference of -1.4 (-3.5 to 0.54), confirming no significant change. A significant increase in cerebral rSO2 occurred during the insufflation period of the CO2 pneumoperitoneum (p = 0.001). Heart rate (F = 11.05; p < 0.001) and mean arterial pressure (MAP) (F = 19.2; p < 0.001) also increased significantly during the laparoscopy. No significant correlation was identified between fluid input and urine output during the laparoscopy (r = 0.012; p = 0.953).

CONCLUSIONS

Renal hypoxia does not occur during laparoscopic surgery in children if the minimum age-appropriate intra-abdominal pressures are used. Alternative causes must account for the oliguria and anuria demonstrated in children undergoing laparoscopy.

The effect of CO2 pneumovesicum on upper urinary tract

OBJECTIVE

Pneumovesicum allows minimal invasive intravesical surgeries. The possible deleterious effect of intravesical CO(2) pressure is not known. We assessed the effect of CO(2) pneumovesicum on the urinary tract and renal function.

METHODS

Pneumovesicum was established and maintained with CO(2) at 10 mm Hg in 10 sows. Cohen cross-trigonal reimplantation was carried out on the left ureter by a vesicoscopic approach. The right ureter was cannulated and served as control. CO(2) pneumovesicum was maintained for 2 hours. Color Doppler measurements of the upper urinary tract and blood sampling were carried out 30 minutes before and 2 hours after establishing pneumovesicum, and 30 minutes after releasing the pneumovesicum.

RESULTS

Compared with the preoperative values, the bilateral anteroposterior diameters of the renal pelves increased significantly after 2 hours of the pneumovesicum (P < .05). Thirty minutes after release of the pneumovesicum, the anteroposterior diameters decreased and showed no statistically significant difference compared with the preoperative values. No air embolus was detected in the ureters, renal pelves, renal veins, or renal arteries on either side 2 hours after establishing the pneumovesicum. There was no statistically significant change in arterial or venous blood flow. There was no significant change in the urea and creatinine levels 2 hours after establishing the pneumovesicum.

CONCLUSION

CO(2) pneumovesicum at a pressure of 10 mm Hg for 2 hours did not result in any demonstrable deleterious effect.

Physiologic Responses to Infrarenal Aortic Cross-Clamping during Laparoscopic or Conventional Vascular Surgery in Experimental Animal Model: Comparative Study

The aim of this study was to compare the hemodynamic and ventilatory effects of prolonged infrarenal aortic cross-clamping in pigs undergoing either laparotomy or laparoscopy. 18 pigs were used for this study. Infrarenal aortic crossclamping was performed for 60 minutes in groups I (laparotomy, n = 6) and II (laparoscopy, n = 6). Group III (laparoscopy, n = 6) underwent a 120-minute long pneumoperitoneum in absence of aortic clamping (sham group). Ventilatory and hemodynamic parameters and renal function were serially determined in all groups. A significant decrease in pH and significant increase in PaCO₂ were observed in group II, whereas no changes in these parameters were seen in group I and III. All variables returned to values similar to baseline in groups I and II 60 minutes after declamping. A significant increase in renal resistive index was evidenced during laparoscopy, with significantly higher values seen in Group II. Thus a synergic effect of pneumoperitoneum and aortic cross-clamping was seen in this study. These two factors together cause decreased renal perfusion and acidosis, thus negatively affecting the patient's general state during this type of surgery.

Effects of different anesthetic techniques on antidiuretic hormone secretion during laparoscopic cholecystectomy

BACKGROUND

With the advent of minimally invasive surgery, laparoscopic cholecystectomy has become the standard treatment for symptomatic gallbladder disease. This study aimed to evaluate the effects of using high- versus low-pressure pneumoperitoneum with different anesthetic techniques on hemodynamics and antidiuretic hormone (ADH) secretion.

METHODS

For this prospective study, 60 patients scheduled for elective laparoscopic cholecystectomy were randomly recruited. They were classified into four equal groups: group 1 received general anesthesia with low insufflation pressure (7-9 mmHg); group 2 received general anesthesia with high insufflation pressure (13-15 mmHg); group 3 received general anesthesia in addition to epidural analgesia with low insufflation pressure; and group 4 received general anesthesia in addition to epidural analgesia with high insufflation pressure. Routine intraoperative monitoring was done. The study parameters included heart rate per minute, mean blood pressure (mmHg), and ADH levels (via blood samples) before anesthesia, after induction, 30 and 45 min after abdominal insufflation, and finally, 2 h postoperatively.

RESULTS

The heart rate showed significant increases after pneumoperitoneum in group 2, as compared with the other three groups. Significant differences in mean blood pressure were observed between the study groups. In groups 1 and 4, mean arterial pressure (MAP) significantly decreased after 15 min, and this decrease persisted until the end of the study. In group 2, MAP significantly increased after 15, 30, 45, and 60 min and after 60 min postoperatively. In group 3, MAP significantly decreased after 30 min, and this decrease persisted 1 h after surgery. There were no significant differences in ADH levels before and after induction of anesthesia among any of the study groups. In groups 1 and 4, no statistically significant changes in ADH levels were observed throughout the study period except a mild increase in ADH levels 30 and 45 min after abdominal insufflation. In group 2, after pneumoperitoneum, there was statistically significant increase in ADH levels from the baseline value of 6.422 +/- 0.551 pmol/l to 7.749 +/- 0.635 pmol/l at 30 min and to 6.457 +/- 0.450 pmol/l at 45 min. In group 3, there was a statistically significant decrease in ADH levels from the baseline value of 6.551 +/- 0.356 pmol/l to 6.125 +/- 0.618 pmol/l at 30 min, to 6.118 +/- 0.491 pmol/l at 45 min, and to 6.169 +/- 0.676 pmol/l at 2 h after abdominal insufflation.

CONCLUSION

Pneumoperitoneum can affect several homeostatic systems, leading to hemodynamic and hormonal stress responses. The use of general anesthesia plus epidural analgesia with low insufflation pressure, general anesthesia with low insufflation pressure, or general anesthesia plus epidural analgesia with high insufflation pressure is safe and effective in attenuating these responses.

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.

Does aggressive hydration reverse the effects of pneumoperitoneum on renal perfusion?

BACKGROUND

Although pneumoperitoneum (PP) decreases renal blood flow, it remains unclear whether this impacts renal function. Our aim was to characterize the effects of PP on renal perfusion and function using two fluid strategies for intravenous fluid administration.

METHODS

Twelve 30-kg pigs were randomized into two groups: maintenance (3 cc/kg/h of normal saline (NS)) and bolus (15 cc/kg/h + 20 cc/kg NaCl bolus prior to induction of PP). Pigs were studied in a blinded fashion for 30 min prior, 60 min during, and 30 min after release of 15 mmHg CO(2) PP. Cardiac output (CO) and stroke volume (SV) were measured using an esophageal Doppler probe, renal cortical perfusion (RCP) was measured with a laser Doppler probe on the right kidney, and renal function was measured using the fractional excretion of sodium (FeNa) and urine output. Statistical analysis was performed with area-under-the-curve (AUC) analysis and analysis of variance

RESULTS

AUC analysis revealed moderate effect size for CO (0.416) and small effect size for SV (0.366) and RCP (0.363), with decreases seen in the control group but not the bolus group. During PP, urine output increased in the bolus group (p = 0.04) but not in the control group; there was no difference in FeNa in either group.

CONCLUSION

Aggressive fluid hydration during CO(2) PP of 15 mmHg preserves CO, SV, and RCP while increasing urine output. No effect on renal function as measured by FeNa was observed in either group.

The physiologic effects of pneumoperitoneum in the morbidly obese

OBJECTIVE

To review the physiologic effects of carbon dioxide (CO2) pneumoperitoneum in the morbidly obese.

SUMMARY BACKGROUND DATA

The number of laparoscopic bariatric operations performed in the United States has increased dramatically over the past several years. Laparoscopic bariatric surgery requires abdominal insufflation with CO2 and an increase in the intraabdominal pressure up to 15 mm Hg. Many studies have demonstrated the adverse consequences of pneumoperitoneum; however, few studies have examined the physiologic effects of pneumoperitoneum in the morbidly obese.

METHODS

A MEDLINE search from 1994 to 2003 was performed using the key words morbid obesity, laparoscopy, bariatric surgery, pneumoperitoneum, and gastric bypass. The authors reviewed papers evaluating the physiologic effects of pneumoperitoneum in morbidly obese subjects undergoing laparoscopy. The topics examined included alteration in acid-base balance, hemodynamics, femoral venous flow, and hepatic, renal, and cardiorespiratory function.

RESULTS

Physiologically, morbidly obese patients have a higher intraabdominal pressure at 2 to 3 times that of nonobese patients. The adverse consequences of pneumoperitoneum in morbidly obese patients are similar to those observed in nonobese patients. Laparoscopy in the obese can lead to systemic absorption of CO2 and increased requirements for CO2 elimination. The increased intraabdominal pressure enhances venous stasis, reduces intraoperative portal venous blood flow, decreases intraoperative urinary output, lowers respiratory compliance, increases airway pressure, and impairs cardiac function. Intraoperative management to minimize the adverse changes include appropriate ventilatory adjustments to avoid hypercapnia and acidosis, the use of sequential compression devices to minimizes venous stasis, and optimize intravascular volume to minimize the effects of increased intraabdominal pressure on renal and cardiac function.

CONCLUSIONS

Morbidly obese patients undergoing laparoscopic bariatric surgery are at risk for intraoperative complications relating to the use of CO2 pneumoperitoneum. Surgeons performing laparoscopic bariatric surgery should understand the physiologic effects of CO2 pneumoperitoneum in the morbidly obese and make appropriate intraoperative adjustments to minimize the adverse changes.

Circulatory and respiratory complications of carbon dioxide insufflation

BACKGROUND

Although providing excellent outcome results, laparoscopy also induces particular pathophysiological changes in response to pneumoperitoneum. Knowledge of the pathophysiology of a CO(2) pneumoperitoneum can help minimize complications while profiting from the benefits of laparoscopic surgery without concerns about its safety.

METHODS

A review of articles on the pathophysiological changes and complications of carbon dioxide pneumoperitoneum as well as prevention and treatment of these complications was performed using the Medline database.

RESULTS

The main pathophysiological changes during CO(2) pneumoperitoneum refer to the cardiovascular system and are mainly correlated with the amount of intra-abdominal pressure in combination with the patient's position on the operating table. These changes are well tolerated even in older and more debilitated patients, and except for a slight increase in the incidence of cardiac arrhythmias, no other significant cardiovascular complications occur. Although there are important pulmonary pathophysiological changes, hypercarbia, hypoxemia and barotraumas, they would develop rarely since effective ventilation monitoring and techniques are applied. The alteration in splanchnic perfusion is proportional with the increase in intra-abdominal pressure and duration of pneumoperitoneum.

CONCLUSION

A moderate-to-low intra-abdominal pressure (<12 mm Hg) can help limit the extent of the pathophysiological changes since consecutive organ dysfunctions are minimal, transient and do not influence the outcome.