- Email: [email protected]
METABOLIC EFFECTS OF CHOLECYSTECTOMY
493
CORRESPONDENCE 5. Mallett SV, RoUes K, Cox D, Burroughs A, Hunt B. Intraopcrative use of aprotinin (Trasylol) in orthotopic liver transplantation. Transplantation Proceedings 1991; 23: 19311932. 6. Thomson JF, Roath OS, Francis JL, Webster JHM, Chant ADB. Aprotinin in peripheral vascular surgery. Lancet 1990; 335:911. 7. Kobrinsky NL, Letts MR, Patcl LR, l-Desamino-8-D arginine vasopressine (Desmopressin) decreases operative blood loss in patients having Harrington rod spinal fusion surgery. Armals of Internal Medicine 1987; 107: 446-450. 8. Salzmann EW, Weinstein MJ, Weintraub RM, Ware JA, Thurer RL, Robertson RL, Donovan A, Gaf&iey T, Bertele V, Troll J, Smith M, Chute LE. Treatment with desmopressin acetate to reduce blood loss after cardiac surgery. New England Journal of Medicine 1986; 314: 1402-1406. 9. Horrow JC, Van Riper DF, Strong MD, Brodsky I, Parmet J. The hemostatic effects of tranexamic acid, and desmopressin during cardiac surgery. Circulation 1991; 84: 20632070. 10. Stems LP, Lillehei CW. Effect of epsilon-aminocaproic acid upon blood loss following open-heart surgery: an analysis of 340 patients. Canadian Journal of Surgery 1967; 10: 304-307.
2. 3. 4. 5.
6.
7.
It should be noted that Dr Simpson's review on perioperative blood loss was commissioned originally as part of a Postgraduate Educational issue, devoted to various aspects of haematology. Some 10-11 articles were commissioned and some of these would have dealt in great detail with the other methods of decreasing blood loss, referred to above by Dr Appadu. Unfortunately, however, most of these reviews failed to materialize and it was not possible to produce a single issue. Thus Dr Simpson's article covered only the area requested of him by the Editor of Educational Reviews. GRAHAM SMITH
Editor
PRE-EMPTIVE EXTRADURAL ANALGESIA Sir,—In their letter, Dr Wilder-Smith and colleagues [1] ask an important question which neither they nor the replying letter [2] address. Why do yet further studies fail "to produce the results expected from previous experimental work [3]" in relation to preemptive analgesia? This previous experimental work with the concept of "preemptive analgesia" and related concepts such as "wind-up" were derived in neurophysiological laboratories in which stimuli are applied to (often neonatal and often decerebrate) animal spinal cord preparations [4], and responses such as the electrical output of neurones including ventral horn (motor) cells [4] measured. In order to obtain the so-called pre-emptive analgesia in rats "lowdose" morphine (0.5 mg kg"1) is used, as opposed to larger doses (5 mg kg"1) needed to suppress this effect when the drug is given after the stimulus [5]. Such industrial doses have no relevance to clinical practice. The phenomenon of wind-up lasts only a few minutes [6] compared with the pain response after injury, which lasts for days. Discussion about the comparative actions of lignocaine or bupivacaine are irrelevant, as there are no comparative studies. In the clinical studies of extradural analgesia [7,8] and peripheral neural block [9], the pain report of conscious man is measured after standard surgical insults. The two experimental systems are assessing totally unrelated events—what would be an even greater surprise would be for there to be any correlation between the two, not that there is a lack of correlation. To answer the question as posed, the studies of analgesia in man "fail to reproduce previous experimental work" because that work was not the study of pain or the response of analgesics in man. Pain is not just nociception. It is only by the study of pain and pain mechanisms in man that there will be any advances in clinical practice. P. A. J. HARDY
Gloucestershire Royal Hospital Gloucester 1. Wilder-Smith OHG, Borgeat A, Tramer M, Morel DR. Pre-
9.
METABOLIC EFFECTS OF CHOLECYSTECTOMY Sir,—We read with interest the study of Joris and colleagues [1] comparing the metabolic and respiratory changes after standard and laparoscopic cholecystectomy. We have compared the same variables after minilaparotomy and laparoscopic cholecystectomy as part of a prospective, randomized controlled trial. In our study, after laparoscopic cholecystectomy there were better postoperative pulmonary function and oxygen saturation, and lower pain scores and morphine consumption using a patient-controlled analgesia device than after a minilaparotomy cholecystectomy [2—4]. In these respects, our findings are in agreement with those of Joris and colleagues. However, our findings on the metabolic response to surgery after the two procedures (10 patients in each group) [5] differ significantly. Serum C reactive protein (CRP) was measured by nephelometry, while serum interleukin-6 (IL-6) was measured using a hybridoma growth stimulation assay. Values were (means (SEM)): CRP at 48 h—laparoscopy 118 (50) mg litre"1, minilaparotomy 122 (30) mg litre"1; IL-6 at 24 h—laparoscopy 227 (41) pg ml"1, minilaparotomy 252 (46) pg ml"1. In our study, there was a wide variation in the metabolic response within groups, but there was no significant difference between the two groups. As a result of a different assay technique, our IL-6 results are substantially greater and cannot be compared directly with those of Joris and colleagues. Furthermore, in our study, the CRP response after laparoscopic cholecystectomy was more than twice that found by Joris and colleagues. Given that there is wide variation in the magnitude of the metabolic response to surgery, it is not surprising that studies with small patient numbers can produce such different results. In the study of Joris and colleagues, patients were not allocated randomly to groups. Patient selection bias may, therefore, account for the difference in findings. A. J. MCMAHON J. N. BAXTER P. J. O'DWYER
Western Infirmary Glasgow 1. Joris J, Cigarini I, Legrand M, Jacquet N, De Groote D, Franchimont P, Lamy M. Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. British Journal of Anaesthesia 1992; 69: 341-345. 2. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russell IT, O'Dwyer PJ. Assessment of pain after
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 4, 2015
8.
emptive cxtradural analgesia. British Journal of Anaesthesia 1992; 69: 663-664. Dahl JB, Hansen BL, Hjortse N-C, Erichsen CJ, Meiniche S, Kehlet H. Pre-emptive extradural analgesia. British Journal of Anaesthesia 1992; 69: 664-665. Woolf CJ. Recent advances in the pathophysiology of acute pain. British Journal of Anaesthesia 1989; 63: 139-146. Wilcox GL. Role of centra] changes in secondary hyperalgesia: Discussion. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 261. Woolf CJ. Excitability changes in central neurons following peripheral damage. Role of central sensirization in the parhogenesis of pain. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 221-243. Haley JE, Wilcox GL. Involvement of excitatory amino acids and peptides in the spinal mechanisms underlying hyperalgesia. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 281-293. Dahl JB, Hansen BL, Hjortse N-C, Erichsen CJ, Meiniche S, Kehlet H. Influence of riming on the effect of continuous extradural analgesia with bupivacaine and morphine after major abdominal surgery. British Journal of Anaesthesia 1992; 69: 4-8. Pryle BJ, Vanner R, Enriquez N, Reynolds F. Can preemptive epidural blockade reduce postoperative pain following lower abdominal surgery? Anaesthesia 1993; (in press). Dierking G, Dahl JB, Kansrrup J, Dahl A, Kehlet H. The effect of pre vs postoperative inguinal field block on postoperative pain following hcrniorrhaphy. British Journal of Anaesthesia 1992; 68: 344-348.
BRITISH JOURNAL OF ANAESTHESIA
494 laparoscopic and minilap cholecystectomy: a randomised trial. British Journal of Surgery 1992; 79: 1224. 3. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russell IT, O'Dwyer PJ. Pulmonary function after laparoscopic and minilap cholecystectomy: a randomised trial. British Journal of Surgery 1992; 79: 1226. 4. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Sunderland G, Russell IT, O'Dwyer PJ. Post-operative pain and analgesia requirement after laparoscopic and minilap cholecystectomy: a prospective randomised trial. Gut 1992; 33: S63. 5. McMahon AJ, O'Dwyer PJ, McMillan D, Cruikshank A, Lowe G, Rumley A, O'Reilly D, Logan R, Baxter JN. Does the laparoscopic method result in a reduced metabolic response to surgery? Irish Journal of Medical Science 1992;
161 (Suppl. 11): 39.
1. Joris J, Cigarini I, Legrand M, Jacquet N, De Groote D, Franchimont P, Lamy M. Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. British Journal of Anaesthesia 1992; 69: 341-345. 2. Putensen-Himmer G, Putensen C, Lammer H, Lingnan W, Aigner F, Bcnzer H. Comparison of postoperative respiratory function after laparoscopy or open laparotomy for cholecystectomy. Anesthesiology 1992; 77: 675-680. 3. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russel M, O'Dwyer PJ. Assessment of pain after laparoscopic and minilap cholecystectomy: a randomized trial. British Journal of Surgery 1992; 79: 1224. 4. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russel M, O'Dwyer PJ. Pulmonary function after laparoscopic and minilap cholecystectomy: a randomized trial. British Journal of Surgery 1992; 79: 1226. 5. Stahl W. Acute phase protein response to tissue injury. Critical Care Medicine 1987; 5: 545-550. 6. Heinrich CA, Cannon JG, Wolff JM. Interleukin-6 and the acute phase response. Biochemical Journal 1990; 265: 621-636. 7. McMahon AJ, O'Dwyer PJ, McMillan D, Cruikshank A, Lowe G, Rumley A, O'Reilly D, Logan R, Baxter JN. Does the laparoscopic method result in a reduced metabolic response to surgery? Irish Journal of Medical Science 1992;
161 (Suppl. 1): 39. 8. Neugebauer E, Troidl H, Spangenberger W, Dietrich A, Lefering G. Conventional versus laparoscopic cholecystectomy and the randomized controlled trial. British Journal of Surgery 1991; 78: 150-154. 9. Nishimoto N, Yoshizaki K, Tagoh H, Monden M, Kishimoto S, Hirano T, Kishimoto T. Elevation of serum interleukin-6 prior to acute phase proteins on the inflammation by surgical operation. Clinical Immunopathology 1989; SO: 399-401. 10. Joris J, Cigarini I, Kamel M, Vrind Y, De Groote D, Franchimont P, Jacquet N, Lamy M. Comparison of the effects of continuous interpleural analgesia and intramuscular opiate PRN on pain metabolic response after cholecystectomy. Regional Anaesthesia 1991; IS: 6. 11. Jakeways MSR, Mitchell V, Hashim IA, Chadwick SJD, Anderson J, Carli F, Shenkin A. Metabolic and inflammatory changes following laparoscopic cholecystectomy. Proceedings of the Nutrition Society 1993; (in press).
ERRATUM British Journal of Anaesthesia 1993; 70: 17-21 Equation (7) should read: dr = &6/2nf In the equation after equation (8) the right hand side should begin, not (kv/2nf), but (kv'/2nf).
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 4, 2015
Sir,—We appreciate the interest of McMahon and colleagues in our work [1] on the metabolic and respiratory changes after standard and laparoscopic cholecystectomy. Using randomized studies, Putensen and colleagues [2] and McMahon and colleagues [3, 4] confirmed better postoperative pulmonary function, greater 5p Ol and smaller pain scores, opioid consumption, or both, after laparoscopic cholecystectomy than after open cholecystectomy as demonstrated in our article. Laparoscopic cholecystectomy avoids a large abdominal incision and attendant retraction. Furthermore, gall bladder dissection "appears" less traumatic, less extensive and more precise during laparoscopy. The reported benefits of laparoscopy on postoperative pulmonary function and pain were therefore expected and, for us, were related mainly to reduction of surgical trauma. We measured C-reactive protein (CRP) and IL-6 to document objectively the reduction in tissue injury. Increases in plasma concentrations of IL-6 and CRP, considered as indicators of the amount of tissue damage [5, 6] were significantly less after laparoscopy. McMahon and colleagues [7], however, could not find any significant difference between laparoscopic and open cholecystectomy. We do not think that patient selection bias accounts for the discrepancies between the findings of their randomized study, and ours which was not randomized. First, our study was carried out early after the introduction of laparoscopic cholecystectomy. All the patients in our study were operated on by experienced senior surgeons, more acquainted with the technique of open than laparoscopic cholecystectomy. We suspect, therefore, that the difference reported in our study would be even greater if the comparisons were to be made now, 2 years later. Second, although the study was carried out shortly after the introduction of laparoscopic cholecystectomy, by the time we decided to undertake it, open cholecystectomies were no longer performed in our hospital except for acute cholecystitis or complicated cases. A randomized, controlled study of open vs laparoscopic cholecystectomy was not appropriate when our study was designed and, I regret, will no longer be possible in the light of the multiple benefits favouring the laparoscopic approach [8]. We therefore used historical controls [1]. We also noticed a wide within-group variation for CRP (measured by nephelometry), but this was still five times less than
that of McMahon and colleagues. Serum concentrations of CRP in their study were very great. The mean concentrations of CRP in our study were in the range reported in other studies [9, 10]. As far as IL-6 is concerned, we used a radioimmunometric assay, whereas McMahon's group used a bioassay; comparison of the two sets of data for IL-6 is therefore difficult. However, Jakeways and colleagues [11], using a bioassay, also reported peak plasma concentrations of IL-6 and CRP significantly greater after laparotomy than after laparoscopy. Moreover, peak plasma concentrations of IL-6 and CRP correlated well in our study. Therefore, as our findings were expected and confirmed clinical observation, we consider our data valid. J. Jows Centre Hospitalier Universitaire Liege
CORRESPONDENCE 5. Mallett SV, RoUes K, Cox D, Burroughs A, Hunt B. Intraopcrative use of aprotinin (Trasylol) in orthotopic liver transplantation. Transplantation Proceedings 1991; 23: 19311932. 6. Thomson JF, Roath OS, Francis JL, Webster JHM, Chant ADB. Aprotinin in peripheral vascular surgery. Lancet 1990; 335:911. 7. Kobrinsky NL, Letts MR, Patcl LR, l-Desamino-8-D arginine vasopressine (Desmopressin) decreases operative blood loss in patients having Harrington rod spinal fusion surgery. Armals of Internal Medicine 1987; 107: 446-450. 8. Salzmann EW, Weinstein MJ, Weintraub RM, Ware JA, Thurer RL, Robertson RL, Donovan A, Gaf&iey T, Bertele V, Troll J, Smith M, Chute LE. Treatment with desmopressin acetate to reduce blood loss after cardiac surgery. New England Journal of Medicine 1986; 314: 1402-1406. 9. Horrow JC, Van Riper DF, Strong MD, Brodsky I, Parmet J. The hemostatic effects of tranexamic acid, and desmopressin during cardiac surgery. Circulation 1991; 84: 20632070. 10. Stems LP, Lillehei CW. Effect of epsilon-aminocaproic acid upon blood loss following open-heart surgery: an analysis of 340 patients. Canadian Journal of Surgery 1967; 10: 304-307.
2. 3. 4. 5.
6.
7.
It should be noted that Dr Simpson's review on perioperative blood loss was commissioned originally as part of a Postgraduate Educational issue, devoted to various aspects of haematology. Some 10-11 articles were commissioned and some of these would have dealt in great detail with the other methods of decreasing blood loss, referred to above by Dr Appadu. Unfortunately, however, most of these reviews failed to materialize and it was not possible to produce a single issue. Thus Dr Simpson's article covered only the area requested of him by the Editor of Educational Reviews. GRAHAM SMITH
Editor
PRE-EMPTIVE EXTRADURAL ANALGESIA Sir,—In their letter, Dr Wilder-Smith and colleagues [1] ask an important question which neither they nor the replying letter [2] address. Why do yet further studies fail "to produce the results expected from previous experimental work [3]" in relation to preemptive analgesia? This previous experimental work with the concept of "preemptive analgesia" and related concepts such as "wind-up" were derived in neurophysiological laboratories in which stimuli are applied to (often neonatal and often decerebrate) animal spinal cord preparations [4], and responses such as the electrical output of neurones including ventral horn (motor) cells [4] measured. In order to obtain the so-called pre-emptive analgesia in rats "lowdose" morphine (0.5 mg kg"1) is used, as opposed to larger doses (5 mg kg"1) needed to suppress this effect when the drug is given after the stimulus [5]. Such industrial doses have no relevance to clinical practice. The phenomenon of wind-up lasts only a few minutes [6] compared with the pain response after injury, which lasts for days. Discussion about the comparative actions of lignocaine or bupivacaine are irrelevant, as there are no comparative studies. In the clinical studies of extradural analgesia [7,8] and peripheral neural block [9], the pain report of conscious man is measured after standard surgical insults. The two experimental systems are assessing totally unrelated events—what would be an even greater surprise would be for there to be any correlation between the two, not that there is a lack of correlation. To answer the question as posed, the studies of analgesia in man "fail to reproduce previous experimental work" because that work was not the study of pain or the response of analgesics in man. Pain is not just nociception. It is only by the study of pain and pain mechanisms in man that there will be any advances in clinical practice. P. A. J. HARDY
Gloucestershire Royal Hospital Gloucester 1. Wilder-Smith OHG, Borgeat A, Tramer M, Morel DR. Pre-
9.
METABOLIC EFFECTS OF CHOLECYSTECTOMY Sir,—We read with interest the study of Joris and colleagues [1] comparing the metabolic and respiratory changes after standard and laparoscopic cholecystectomy. We have compared the same variables after minilaparotomy and laparoscopic cholecystectomy as part of a prospective, randomized controlled trial. In our study, after laparoscopic cholecystectomy there were better postoperative pulmonary function and oxygen saturation, and lower pain scores and morphine consumption using a patient-controlled analgesia device than after a minilaparotomy cholecystectomy [2—4]. In these respects, our findings are in agreement with those of Joris and colleagues. However, our findings on the metabolic response to surgery after the two procedures (10 patients in each group) [5] differ significantly. Serum C reactive protein (CRP) was measured by nephelometry, while serum interleukin-6 (IL-6) was measured using a hybridoma growth stimulation assay. Values were (means (SEM)): CRP at 48 h—laparoscopy 118 (50) mg litre"1, minilaparotomy 122 (30) mg litre"1; IL-6 at 24 h—laparoscopy 227 (41) pg ml"1, minilaparotomy 252 (46) pg ml"1. In our study, there was a wide variation in the metabolic response within groups, but there was no significant difference between the two groups. As a result of a different assay technique, our IL-6 results are substantially greater and cannot be compared directly with those of Joris and colleagues. Furthermore, in our study, the CRP response after laparoscopic cholecystectomy was more than twice that found by Joris and colleagues. Given that there is wide variation in the magnitude of the metabolic response to surgery, it is not surprising that studies with small patient numbers can produce such different results. In the study of Joris and colleagues, patients were not allocated randomly to groups. Patient selection bias may, therefore, account for the difference in findings. A. J. MCMAHON J. N. BAXTER P. J. O'DWYER
Western Infirmary Glasgow 1. Joris J, Cigarini I, Legrand M, Jacquet N, De Groote D, Franchimont P, Lamy M. Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. British Journal of Anaesthesia 1992; 69: 341-345. 2. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russell IT, O'Dwyer PJ. Assessment of pain after
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 4, 2015
8.
emptive cxtradural analgesia. British Journal of Anaesthesia 1992; 69: 663-664. Dahl JB, Hansen BL, Hjortse N-C, Erichsen CJ, Meiniche S, Kehlet H. Pre-emptive extradural analgesia. British Journal of Anaesthesia 1992; 69: 664-665. Woolf CJ. Recent advances in the pathophysiology of acute pain. British Journal of Anaesthesia 1989; 63: 139-146. Wilcox GL. Role of centra] changes in secondary hyperalgesia: Discussion. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 261. Woolf CJ. Excitability changes in central neurons following peripheral damage. Role of central sensirization in the parhogenesis of pain. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 221-243. Haley JE, Wilcox GL. Involvement of excitatory amino acids and peptides in the spinal mechanisms underlying hyperalgesia. In: Willis WD, ed. Hyperalgesia and Allodynia. New York: Raven Press, 1991; 281-293. Dahl JB, Hansen BL, Hjortse N-C, Erichsen CJ, Meiniche S, Kehlet H. Influence of riming on the effect of continuous extradural analgesia with bupivacaine and morphine after major abdominal surgery. British Journal of Anaesthesia 1992; 69: 4-8. Pryle BJ, Vanner R, Enriquez N, Reynolds F. Can preemptive epidural blockade reduce postoperative pain following lower abdominal surgery? Anaesthesia 1993; (in press). Dierking G, Dahl JB, Kansrrup J, Dahl A, Kehlet H. The effect of pre vs postoperative inguinal field block on postoperative pain following hcrniorrhaphy. British Journal of Anaesthesia 1992; 68: 344-348.
BRITISH JOURNAL OF ANAESTHESIA
494 laparoscopic and minilap cholecystectomy: a randomised trial. British Journal of Surgery 1992; 79: 1224. 3. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russell IT, O'Dwyer PJ. Pulmonary function after laparoscopic and minilap cholecystectomy: a randomised trial. British Journal of Surgery 1992; 79: 1226. 4. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Sunderland G, Russell IT, O'Dwyer PJ. Post-operative pain and analgesia requirement after laparoscopic and minilap cholecystectomy: a prospective randomised trial. Gut 1992; 33: S63. 5. McMahon AJ, O'Dwyer PJ, McMillan D, Cruikshank A, Lowe G, Rumley A, O'Reilly D, Logan R, Baxter JN. Does the laparoscopic method result in a reduced metabolic response to surgery? Irish Journal of Medical Science 1992;
161 (Suppl. 11): 39.
1. Joris J, Cigarini I, Legrand M, Jacquet N, De Groote D, Franchimont P, Lamy M. Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. British Journal of Anaesthesia 1992; 69: 341-345. 2. Putensen-Himmer G, Putensen C, Lammer H, Lingnan W, Aigner F, Bcnzer H. Comparison of postoperative respiratory function after laparoscopy or open laparotomy for cholecystectomy. Anesthesiology 1992; 77: 675-680. 3. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russel M, O'Dwyer PJ. Assessment of pain after laparoscopic and minilap cholecystectomy: a randomized trial. British Journal of Surgery 1992; 79: 1224. 4. McMahon AJ, Baxter JN, Anderson JR, Ramsay G, Galloway D, Russel M, O'Dwyer PJ. Pulmonary function after laparoscopic and minilap cholecystectomy: a randomized trial. British Journal of Surgery 1992; 79: 1226. 5. Stahl W. Acute phase protein response to tissue injury. Critical Care Medicine 1987; 5: 545-550. 6. Heinrich CA, Cannon JG, Wolff JM. Interleukin-6 and the acute phase response. Biochemical Journal 1990; 265: 621-636. 7. McMahon AJ, O'Dwyer PJ, McMillan D, Cruikshank A, Lowe G, Rumley A, O'Reilly D, Logan R, Baxter JN. Does the laparoscopic method result in a reduced metabolic response to surgery? Irish Journal of Medical Science 1992;
161 (Suppl. 1): 39. 8. Neugebauer E, Troidl H, Spangenberger W, Dietrich A, Lefering G. Conventional versus laparoscopic cholecystectomy and the randomized controlled trial. British Journal of Surgery 1991; 78: 150-154. 9. Nishimoto N, Yoshizaki K, Tagoh H, Monden M, Kishimoto S, Hirano T, Kishimoto T. Elevation of serum interleukin-6 prior to acute phase proteins on the inflammation by surgical operation. Clinical Immunopathology 1989; SO: 399-401. 10. Joris J, Cigarini I, Kamel M, Vrind Y, De Groote D, Franchimont P, Jacquet N, Lamy M. Comparison of the effects of continuous interpleural analgesia and intramuscular opiate PRN on pain metabolic response after cholecystectomy. Regional Anaesthesia 1991; IS: 6. 11. Jakeways MSR, Mitchell V, Hashim IA, Chadwick SJD, Anderson J, Carli F, Shenkin A. Metabolic and inflammatory changes following laparoscopic cholecystectomy. Proceedings of the Nutrition Society 1993; (in press).
ERRATUM British Journal of Anaesthesia 1993; 70: 17-21 Equation (7) should read: dr = &6/2nf In the equation after equation (8) the right hand side should begin, not (kv/2nf), but (kv'/2nf).
Downloaded from http://bja.oxfordjournals.org/ at New York University on June 4, 2015
Sir,—We appreciate the interest of McMahon and colleagues in our work [1] on the metabolic and respiratory changes after standard and laparoscopic cholecystectomy. Using randomized studies, Putensen and colleagues [2] and McMahon and colleagues [3, 4] confirmed better postoperative pulmonary function, greater 5p Ol and smaller pain scores, opioid consumption, or both, after laparoscopic cholecystectomy than after open cholecystectomy as demonstrated in our article. Laparoscopic cholecystectomy avoids a large abdominal incision and attendant retraction. Furthermore, gall bladder dissection "appears" less traumatic, less extensive and more precise during laparoscopy. The reported benefits of laparoscopy on postoperative pulmonary function and pain were therefore expected and, for us, were related mainly to reduction of surgical trauma. We measured C-reactive protein (CRP) and IL-6 to document objectively the reduction in tissue injury. Increases in plasma concentrations of IL-6 and CRP, considered as indicators of the amount of tissue damage [5, 6] were significantly less after laparoscopy. McMahon and colleagues [7], however, could not find any significant difference between laparoscopic and open cholecystectomy. We do not think that patient selection bias accounts for the discrepancies between the findings of their randomized study, and ours which was not randomized. First, our study was carried out early after the introduction of laparoscopic cholecystectomy. All the patients in our study were operated on by experienced senior surgeons, more acquainted with the technique of open than laparoscopic cholecystectomy. We suspect, therefore, that the difference reported in our study would be even greater if the comparisons were to be made now, 2 years later. Second, although the study was carried out shortly after the introduction of laparoscopic cholecystectomy, by the time we decided to undertake it, open cholecystectomies were no longer performed in our hospital except for acute cholecystitis or complicated cases. A randomized, controlled study of open vs laparoscopic cholecystectomy was not appropriate when our study was designed and, I regret, will no longer be possible in the light of the multiple benefits favouring the laparoscopic approach [8]. We therefore used historical controls [1]. We also noticed a wide within-group variation for CRP (measured by nephelometry), but this was still five times less than
that of McMahon and colleagues. Serum concentrations of CRP in their study were very great. The mean concentrations of CRP in our study were in the range reported in other studies [9, 10]. As far as IL-6 is concerned, we used a radioimmunometric assay, whereas McMahon's group used a bioassay; comparison of the two sets of data for IL-6 is therefore difficult. However, Jakeways and colleagues [11], using a bioassay, also reported peak plasma concentrations of IL-6 and CRP significantly greater after laparotomy than after laparoscopy. Moreover, peak plasma concentrations of IL-6 and CRP correlated well in our study. Therefore, as our findings were expected and confirmed clinical observation, we consider our data valid. J. Jows Centre Hospitalier Universitaire Liege