26 Nov 11
Posted in Anesthesia, Laparoscopic surgery at 1:09 by Laci
By R Meierhenrich, A Gauss, P Vandenesch, M Georgieff, B Poch, W Schütz
Anesth Analg 2005;100:340-347
Conflicting results have been published about the effects of carbon dioxide (CO2) pneumoperitoneum on splanchnic and liver perfusion. Several experimental studies described a pressure-related reduction in hepatic blood flow, whereas other investigators reported an increase as long as the intraabdominal pressure (IAP) remained less than 16 mm Hg. Our goal in the present study was to investigate the effects of insufflated CO2 on hepatic blood flow during laparoscopic surgery in healthy adults. Blood flow in the right and middle hepatic veins was assessed in 24 patients undergoing laparoscopic surgery by use of transesophageal Doppler echocardiography. Hepatic venous blood flow was recorded before and after 5, 10, 20, 30, and 40 min of pneumoperitoneum, as well as 1 and 5 min after deflation. Twelve patients undergoing conventional hernia repair served as the control group. The induction of pneumoperitoneum produced a significant increase in blood flow of the right and middle hepatic veins. Five minutes after insufflation of CO2 the median right hepatic blood flow index increased from 196 mL/min/m2 (95% confidence interval (CI), 140–261 mL/min/m2) to 392 mL/min/m2 (CI, 263–551 mL/min/m2) (P < 0.05) and persisted during maintenance of pneumoperitoneum. In the middle hepatic vein the blood flow index increased from 105 mL/min/m2 (CI, 71–136 mL/min/m2) to 159 mL/min/m2 (CI, 103–236 mL/min/m2) 20 min after insufflation of CO2. After deflation blood flow returned to baseline values in both hepatic veins. Conversely, in the control group hepatic blood flow remained unchanged over the entire study period. We conclude that induction of CO2 pneumoperitoneum with an IAP of 12 mm Hg is associated with an increase in hepatic perfusion in healthy adults.
Implications
Blood flow in the right and middle hepatic veins was studied by use of transesophageal echocardiography in 24 patients undergoing laparoscopic surgery. CO2 pneumoperitoneum induced a significant increase in hepatic venous blood flow. This finding is in contrast to results of experimental studies suggesting that CO2 pneumoperitoneum may be harmful to liver function as a result of impaired perfusion.
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16 Nov 11
Posted in Anesthesia, Laparoscopic surgery at 0:06 by Laci
By C D McClain, F X McGowan, P Kovatsis
Anesth Analg 2006;103:856-858
Laparoscopic surgery represents a significant advance in surgical technique, but a number of physiologic sequelae result from positioning and insufflation. These physiologic changes may be more significant in patients with complex congenital heart disease. We present the anesthetic management of a patient with Fontan physiology who successfully underwent two separate laparoscopic procedures.
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08 Nov 11
Posted in Anesthesia at 1:01 by Laci
By B Mraovic, T Šimurina, Z Sonicki, N Skitarelić, T J. Gan
Anesth Analg September 2008 107:818-823
Whether nitrous oxide (N2O) increases the incidence of postoperative nausea and vomiting (PONV) after laparoscopic gynecologic surgery is still controversial, which may be due to the administration of different concentrations of inspired N2O. We investigated whether N2O results in a dose–response increase in PONV.
Methods
Patients undergoing gynecologic laparoscopic surgery were randomized to receive 30% oxygen with air (G0, n = 46), 50% N2O with oxygen (G50, n = 46), or 70% N2O with oxygen (G70, n = 45). A standardized general anesthetic was used with no PONV prophylaxis. Known risk factors for PONV were controlled. Metoclopramide was used as a rescue antiemetic. The incidence of nausea, vomiting, use of rescue antiemetic, and pain visual analog scale (VAS) score was measured at 2 and 24 h postoperatively.
Results
Patient demographics were comparable, and there were no differences among groups regarding factors that may influence PONV. The incidence of PONV at 24 h was 33% (15 of 46) in the G0 group, 46% (21 of 46) in the G50 group, and 62% (28 of 45) in the G70 group (P = 0.018). Subgroup analysis revealed a difference between G0 versus G70 groups (P = 0.018), but no significant difference between G0 versus G50 groups and G50 versus G70 groups. The incidence of nausea showed a similar difference (G0 = 26%, G50 = 35%, and G70 = 56%; P = 0.012), but the incidence of vomiting was not different among the groups although there was a trend (G0 = 28%, G50 = 35%, and G70 = 42%; P = 0.377). The severity of nausea (measured by VAS 100 mm) was significantly increased with increasing N2O concentration (G0 = 10.9, G50 = 12.7, and G70 = 20.5; P = 0.027). The highest VAS score during 24 h was used for the analysis. There was no difference in the use of a rescue antiemetic among groups. Pain VAS scores and opioids consumption were not different among groups (at 2 and 24 h after surgery).
Conclusions
N2O increases the incidence of postoperative nausea after gynecologic laparoscopic surgery. This preliminary finding indicates that N2O may increase PONV in a dose-dependent fashion. A study with a sample size of >400 patients in each group would be necessary to demonstrate a statistically significant difference among each of these three groups. We do not recommend using a high concentration of N2O in this clinical setting.
Implications
We demonstrate that nitrous oxide (N2O) increases the incidence of postoperative nausea and vomiting (PONV) after laparoscopic gynecologic surgery. The preliminary findings indicate that N2O may increase PONV in a dose-dependent fashion. A high concentration of N2O in this clinical setting is not recommended.
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04 Nov 11
Posted in Monitoring at 0:47 by Laci
By R Thiele and M Durieux
Anesth Analg 2011;113:766-776
Qualitative arterial waveform analysis has been in existence for millennia; quantitative arterial waveform analysis techniques, which can be traced back to Euler’s work in the 18th century, have not been widely used by anesthesiologists and other clinicians. This is likely attributable, in part, to the widespread use of the sphygmomanometer, which allows the practitioner to assess arterial blood pressure without having to develop a sense for the higher-order characteristics of the arterial waveform. The 20-year delay in the development of devices that measure these traits is a testament to the primitiveness of our appreciation for this information. The shape of the peripheral arterial pressure waveform may indeed contain information useful to the anesthesiologist and intensivist. The maximal slope of the peripheral arterial pressure tracing seems to be related to left ventricular contractility, although the relationship may be confounded by other hemodynamic variables. The area under the peripheral arterial pressure tracing is related to stroke volume when loading conditions are stable; this finding has been used in the development of several continuous cardiac output monitors. Pulse wave velocity may be related to vascular impedance and could potentially improve the accuracy of waveform-based stroke volume estimates. Estimates of central arterial pressures (e.g., aortic) can be produced from peripheral (e.g., brachial, radial) tracings using a Generalized Transfer Function, and are incorporated into the algorithms of several continuous cardiac output monitors.
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