1Département dAnesthésie-Réanimation, AP-HP Hôpital Henri Mondor and Université Paris XII, Créteil, France. 2Service de Chirurgie digestive, AP-HP Hôpital Henri Mondor and Université Paris XII, Créteil, France*Corresponding author: Département dAnesthésie-Réanimation, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, F-94010 Créteil Cedex, France
Accepted for publication: May 3, 2001
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Abstract |
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Br J Anaesth 2001; 87: 4936
Keywords: surgery, liver resection; veins, portal triad clamping; complications, pneumoperitoneum; blood, haemodynamics
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Introduction |
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We studied PTC performed during laparoscopy and compared the haemodynamic responses with the responses to PTC during laparotomy, and assessed the possible adverse effects of such changes.
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Methods and results |
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Between May 1999 and February 2000, we studied 10 consecutive adult patients undergoing elective liver resection done laparoscopically (laparoscopy group). The liver segments that can be safely resected laparoscopically are the anterior and lateral segments (segments IIVI).1 Laparoscopic resection was performed for peripheral lesions 5 cm or less in size, and resections were limited to three segments or fewer.1 Tumours in posterior and superior segments (i.e. segments I, VII and VIII) should not be considered because of difficult laparoscopic access and connections with the inferior vena cava and major hepatic veins.1 The carbon dioxide pneumoperitoneum was induced with 14 mm Hg intra-abdominal pressure in the supine position before a 20° head-up tilt. A control group of 10 consecutive patients undergoing liver resection performed via an abdominal incision (open group) was studied similarly. Intermittent PTC was applied with 15-min clamping and 5-min release periods.6
Anaesthetic management and intraoperative care were standardized throughout the study. General anaesthesia was induced with thiopental 46 mg kg1 and sufentanil 0.3 µg kg1 i.v. After orotracheal intubation, facilitated with atracurium 0.5 mg kg1, anaesthesia was maintained with 0.51.5% end-tidal isoflurane together with a continuous infusion of sufentanil 0.3 µg kg1 h1, and muscular relaxation was maintained by a continuous infusion of atracurium 0.5 mg kg1 h1. Crystalloid solution was infused during operation at a basal rate of 10 ml kg1 h1. The inspired oxygen fraction was set at 50% in air and minute ventilation was adjusted to maintain arterial carbon dioxide below 45 mm Hg.
After induction of general anaesthesia, one radial artery was cannulated and a 7.5 F thermodilution Edwards SwanGanz catheter (Baxter, Irvine, CA, USA) was introduced via the right internal jugular vein. Pressures were obtained after calibration, zeroing to atmospheric pressure and using the midchest level as reference. We recorded MAP, pulmonary artery pressure, right atrial pressure and pulmonary artery occlusion pressure, all at end-expiration. Cardiac output was measured using the thermodilution technique, and an extent of variation less than 10% was considered permissible when taking the average of three measurements.
The first period of PTC during the surgical procedure was studied. Haemodynamic data were collected 5 min before PTC (T1), 5 min after clamping (T2) and 5 min after clamp release (T3) in the two groups.
Data were analysed with the Statview 5.0 statistical packages (SAS Institute, Cary, NC, USA). Data are presented as mean (SD) unless otherwise stated. Intergroup comparisons were made with the 2 test or Fishers exact test for categorical variables, and Students t-test or the MannWhitney U-test when appropriate for continuous variables. Changes in variables within the two groups were subjected to analysis of variance (ANOVA) followed by the NeumanKeuls test, as appropriate. Assuming a decrease in CI of 30% to be clinically important, we estimated that 10 patients in each group would be adequate to test the null hypothesis at 0.05 significance with a power of 0.83. A P value <0.05 was considered statistically significant.
Study population
The two groups of patients were similar in clinical characteristics, duration of surgery before PTC, blood loss and total i.v. infusion (Table 1). No severe perioperative cardiopulmonary complications were observed. No vasoactive drugs were used during PTC. All patients recovered uneventfully, except for one patient who had nosocomial Legionnella pneumonia but recovered satisfactorily.
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Before PTC, haemodynamic values were similar in the two groups. In the laparoscopic procedures, during PTC, MAP remained stable [2 (11)%, not significant], SVR rose by 37 (45)% (T2 vs T1, P<0.01) and CI decreased by 19 (17)% (T2 vs T1, P<0.01) (Table 2). In the open procedures, during PTC, MAP increased by 18 (18)% (T2 vs T1, P<0.01), SVR increased by 36 (28)% (T2 vs T1, P<0.01) and CI decreased by 9 (16)% (not significant) (Table 2). There were no differences between the two groups other than a moderate increase in MAP in open group [open group, 108 (19) mm Hg; laparoscopy group, 84±8 mm Hg; P<0.05].
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Comment |
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In the present study, conditions before PTC were similar in the two groups despite the pneumoperitoneum. Pneumoperitoneum causes increases in arterial pressure and SVR.4 Changes in cardiac output are variable, consistent with the Starling resistor concept of abdominal venous return.8 Moreover, the reverse Trendelenburg position causes a further decrease in preload.4 However, these haemodynamic changes were not sustained throughout the period of pneumoperitoneum.4 The partial correction of the haemodynamic variables during pneumoperitoneum may have been caused by the vasodilating properties of isoflurane.4
In fact, PTC during laparoscopy did not cause significant haemodynamic changes compared with the open procedures. The MAP was stable, CI decreased slightly and SVR increased. We suggest that an increase in SVR counteracted the moderate decrease in CI, so that MAP remained at the preclamping level. The mild decrease in CI could be explained by a preload that was insufficient3 8 to compensate for the increased stroke work necessary to maintain cardiac output.9 During the laparotomy, the normal heart could become sensitive to changes in afterload, as in heart failure.5 10 The mild decrease in CI during PTC performed under laparoscopy can be explained by a decrease in venous return and/or an increase in SVR. These haemodynamic changes were not great enough to necessitate stopping the procedure or to release the PTC.
In conclusion, in a small number of patients, we could not find a difference in haemodynamic changes during PTC during laparotomy, and PTC carried out during an open surgical procedure. However, this lack of difference could be a result of inadequate power of the study. Laparoscopic liver resections with PTC are feasible and safe in patients with normal cardiac function.
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Acknowledgement |
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References |
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