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1 Original Article Article original ALTERATIONS IN RESPIRATORY MECHANICS AFTER LAPAROSCOPIC AND OPEN SURGICAL PROCEDURES Nicholas A. Kimberley, MD; * Susan M. Kirkpatrick, RN; James M. Watters, MD, FRCSC, FACS OBJECTIVE: To compare the effects of laparoscopic and open surgical procedures on postoperative strength and respiratory mechanics. DESIGN: Prospective cohort study. SETTING: Adult university hospital. PARTICIPANTS: Fifty-one women aged 21 to 62 years scheduled to undergo elective cholecystectomy or hysterectomy (or related procedures), otherwise in good health. INTERVENTION: Open or laparoscopic cholecystectomy or hysterectomy (or related procedures). MAIN OUTCOME MEASURES: Maximum voluntary handgrip strength (HGS), forced vital capacity (VC), forced expiratory volume in 1 second (FEV 1 ), and maximal inspiratory pressure (MIP) were each measured preoperatively and on the first postoperative morning. A visual analogue pain scale score was evaluated in relation to performance of the postoperative strength and respiratory measurements. RESULTS: VC, FEV 1 and MIP, but not HGS, were decreased after surgery. Postoperative VC, FEV 1 and MIP were lower after open procedures than after laparoscopic procedures and after cholecystectomy than after hysterectomy (all p < 0.001). Pain scores were lower after laparoscopic than after open procedures (p < 0.005) and could account in part for differences in postoperative respiratory mechanics. CONCLUSIONS: Cholecystectomy and hysterectomy do not result in generalized muscle weakness, unlike more major abdominal procedures. Postoperative alterations in respiratory mechanics are related to the site of the surgery, the use of an open versus a laparoscopic approach and postoperative pain. OBJECTIF : Comparer les effets d interventions par laparoscopie et par chirurgie ouverte sur la résistance et la mécanique respiratoire après l intervention. CONCEPTION : Étude prospective de cohortes. CONTEXTE : Hôpital universitaire pour adultes. PARTICIPANTS : Cinquante et une femmes de 21 à 62 ans qui devaient subir une cholécystectomie élective, une hystérectomie ou des interventions connexes et qui étaient autrement en bonne santé. INTERVENTION : Cholécystectomie, hystérectomie ou interventions connexes par chirurgie ouverte ou par laparoscopie. PRINCIPALES MESURES DES RÉSULTATS : La puissance maximale de la poignée de main volontaire, la capacité vitale forcée, le volume respiratoire maximal à une seconde et la pression inspiratoire maximale ont été mesurés avant l intervention et le lendemain matin. On a évalué un résultat de l échelle analogique visuelle en fonction de la force et de la respiration mesurées après l intervention. RÉSULTATS : La capacité vitale forcée, le volume respiratoire maximal à une seconde et la pression inspiratoire maximale, mais non la puissance de la poignée de main, ont diminué après l intervention chirurgicale. La capacité vitale, le volume respiratoire maximal à une seconde et la pression inspiratoire maximale étaient plus faibles après une chirurgie ouverte qu après une laparoscopie, et moins élevés après une cholécystec- From the Division of General Surgery, University of Ottawa, Ottawa Civic Hospital, Ottawa, Ont. *Former resident in general surgery, University of Ottawa Accepted for publication Nov. 15, 1995 Correspondence and reprint requests to: Dr. James M. Watters, Division of General Surgery, Ottawa Civic Hospital, 1053 Carling Ave., Ottawa ON K1Y 4E Canadian Medical Association (text and abstract/résumé) 312 JCC, Vol. 39, N o 4, août 1996

2 RESPIRATORY MECHANICS AFTER SURGERY tomie qu après une hystérectomie (tous p < 0,001). Les douleurs étaient moindres après la laparoscopie qu après les interventions ouvertes (p < 0,005) et pourraient expliquer en partie les écarts au niveau de la mécanique respiratoire postopératoire. CONCLUSIONS : La cholécystectomie et l hystérectomie n entraînent pas de faiblesse musculaire généralisée, contrairement à des interventions abdominales plus graves. Les changements postopératoires de la mécanique respiratoire sont liés au site de l intervention chirurgicale, au recours à la chirurgie ouverte plutôt qu à la laparoscopie et à la douleur postopératoire. Surgical procedures impose physiologic costs on patients that may have important functional and clinical consequences. Major abdominal procedures are accompanied by altered respiratory mechanics as well as a generalized reduction in muscle strength. 1 The factors that may influence the physiologic effects of abdominal surgery include those related to the specific procedure (e.g., the magnitude of tissue dissection and the surgical site), to the patient (e.g., age and preoperative physiologic and medical status) and to perioperative care (e.g., postoperative pain, starvation and physical inactivity). The purpose of this study was to compare the effects of laparoscopic versus open surgical approaches on postoperative respiratory mechanics and muscle strength. METHODS Women in good general health, ranging in age from 21 to 62 years, were studied before and after four open and laparoscopic procedures as follows: open cholecystectomy (3 patients), laparoscopic cholecystectomy (29 patients), abdominal (open) hysterectomy (14 patients) and laparoscopic hysterectomy or other major gynecologic procedure (5 patients). Excluded were patients who had asthma, chronic lung disease, arthritis, or neuromuscular, metabolic or other disorders that might interfere with the measurements. Maximum voluntary handgrip strength (HGS), vital capacity (VC), maximal inspiratory pressure (MIP), and forced expiratory volume in 1 second (FEV 1 ) were measured at the preadmission hospital visit, early on the morning of surgery (preoperative) and on the morning after surgery (postoperative). HGS was taken as the highest of three maximal voluntary contractions in the dominant hand 30 to 60 seconds apart, with the patient seated in a position of maximal comfort. HGS was measured with the use of a handgrip dynamometer (Jamar model 1 dynamometer; J.A. Preston, Toronto). 2 MIP after tidal expiration, that is, at functional residual capacity, was measured with a pressure manometer (A.F. Hall, Burlington, Ont.). 3 VC and FEV 1 were measured with a portable spirometer (Vitalograph Compact; Roxon Medi-Tech, Montreal). Pain was evaluated in relation to the performance of the postoperative strength measurements and spirometry on a visual analogue scale. 4 Patients were studied at least 1 hour after the administration of any narcotic. The protocol was reviewed and approved by the Research Ethics Committee of the Ottawa Civic Hospital, and written consent was obtained from all patients. All measurements in a Table I given patient were conducted by one individual. Data were analysed by analysis of variance, Tukey s honestly significant difference (HSD) test, the paired t-test, and multiple linear regression. The results aregiven as means (and standard deviations). RESULTS Demographic Data on Patients in the Four Procedure Groups Variable Mean (and SD) age, yr Mean (and SD) weight, kg Mean (and SD) body mass index, kg/m 2 Smoker, no. of patients Yes No OC (n = 3) 43 (15) 79 (12) (5) Patients in the four procedure groups were similar in terms of age, weight, body mass index, smoking status and preoperative VC, FEV 1, MIP and HGS (Tables I and II). erative VC and FEV 1 increased as a function of height and decreased with age (r 2 = 0.38 and 0.48, respectively, all p < 0.002). HGS was weakly related to height (r 2 = 0.11, p < 0.05). Smoking status did not influence preoperative VC, FEV 1, MIP or HGS. The differences in the duration of open hysterectomy and laparoscopic hysterectomy (p = 0.06) and open cholecystectomy (which included two conversions from laparoscopic procedures) (Table II) approached statistical significance (p = 0.08). LC (n = 29) 41 (12) 73 (19) (7) OH (n = 14) (15) (8) LH (n = 5) (10) OC = open cholecystectomy, LC = laparoscopic cholecystectomy, OH = open hysterectomy, LH = laparoscopic hysterectomy (5) CJS, Vol. 39, No. 4, August

3 KIMBERLEY, KIRKPATRICK, WATTERS Table II Postop 14 (12) 34 (10) Handgrip strength, kg 35 (3) 31 (6) VC, FEV 1 and MIP (all p < 0.001) were decreased on the morning after operation, but HGS was not altered (Table II). Postoperative VC, FEV 1 and MIP (expressed as a proportion of preoperative values) were lower after open than after laparoscopic procedures, and after cholecystectomy than after hysterectomy (all p 0.001) (Fig. 1). VC, FEV 1 and MIP were lowest after open cholecystectomy (p < 0.005, 0.005, and 0.05 respectively versus other groups). Percent changes postoperatively were not re- Mean (and SD) Measurements of Strength and Respiratory Mechanics in 51 Women Who Underwent Open or Laparoscopic Cholecystectomy or Hysterectomy Measurement Vital capacity, L 3.6 (0.7) Postop 1.4 (0.6) 2.8 (0.7) 3.1 (0.6) Forced expiratory volume in 1 s, L Postop Maximal inspiratory pressure, cm H 2 O OC (n = 3) 3.0 (0.3) 2.3 (0.2) 1.0 (0.3) 43 (20) Postop 34 (2) 30 Visual analogue pain scale score, mm 63 (13) LC (n = 29) 2.8 (0.6) 2.1 (0.6) 47 (12) (6) OH (n = 14) 3.7 (0.5) 2.8 (0.3) 2.4 (0.5) 46 (21) 34 (14) (6) (7) LH (n = 5) 4.1 (0.3) 3.7 (0.3) 3.2 (0.2) 3.0 (0.2) 57 (17) 51 (15) (3) 32 (19) 38 (23) 30 (29) Duration of procedure, min 160 (83) 118 (30) 98 (27) 151 (79) lated to preoperative values. Postoperative pain scores on a visual analogue scale were quite variable but were lower after laparoscopic than after open procedures (p < 0.05) (Fig. 2). FEV 1 (p < 0.05), MIP and VC (both p = 0.07) after surgery were weakly related to the pain scale score on univariate analysis. Pain scale scores were more strongly related to postoperative VC (r 2 = 0.20, p < 0.05), FEV 1 (r 2 = 0.28, p < 0.01) and MIP (r 2 = 0.11, p = 0.07) when the site of surgery was accounted for, but were no longer predictors when the use of a laparoscopic versus open approach was included in the analysis. Postoperative VC, FEV 1 and MIP were not influenced by age, smoking status, weight, height or duration of surgery. DISCUSSION Muscle strength and lung volumes are related to age and sex, in part reflecting differences in muscle mass. 1 To minimize such variability and facilitate recruitment of generally healthy individuals to the various groups, we chose to study young and middleaged women scheduled to undergo the procedures described. Even within this relatively homogeneous group, FIG. 1. Postoperative vital capacity (VC, left panel) and maximal inspiratory pressure (MIP, right panel) in each of four procedure groups (OC = open cholecystectomy, LC = laparoscopic cholecystectomy, OH = open hysterectomy, LH = laparoscopic hysterectomy) expressed as mean (and standard deviation) of percentage of preoperative values. *All p < (VC) and p < 0.05 (MIP) versus other groups. FIG. 2. Visual analogue pain scale scores (in millimetres) in each of procedure groups expressed as mean (and SD). 314 JCC, Vol. 39, N o 4, août 1996

4 RESPIRATORY MECHANICS AFTER SURGERY age and body size (i.e., height) effects accounted for much of the variability in VC and FEV 1 although not that of HGS. Cholecystectomy and hysterectomy were chosen as being commonly performed laparoscopic and open surgical procedures that are of comparable magnitude in terms of tissue dissection and are conducted in similar, relatively homogeneous and healthy demographic groups. Patients scheduled to undergo open cholecystectomy and major laparoscopic gynecologic procedures were also studied in an attempt to account for differences between upper and lower abdominopelvic procedures. The four groups were similar in terms of age, weight and other preoperative variables. The duration of the open hysterectomy tended to be shorter than those of open cholecystectomy and laparoscopic hysterectomy, but the duration of a surgical procedure was not a predictor of postoperative respiratory mechanics or other variables. Muscle strength decreases after surgery in a dose-dependent fashion, that is, changes are most marked after major surgical procedures and are minimal or absent after minor procedures. 5,6 MIP as well as VC and FEV 1 reflect respiratory muscle strength in part. 3 However, the procedures we studied are limited in magnitude and did not result in changes in HGS, that is, in generalized muscle weakness. Thus, other factors must contribute to the observed changes in respiratory mechanics. Decreases in VC and FEV 1 after open abdominal surgery are well known to be influenced by the site of surgery, and our observations in patients who underwent open cholecystectomy and hysterectomy are similar to those of others. 7 9 Alterations in diaphragm function contribute to the decreases in VC and FEV 1 that follow upper but not lower abdominal surgery, with neurologic reflex inhibition postulated as the physiologic basis. 9,10 A recent study comparing laparoscopic cholecystectomy and herniorrhaphy, demonstrated that even with a laparoscopic approach, surgery in the upper abdomen results in significant postoperative impairment of diaphragm function. 11 Our observations also are consistent with the concept that the site of surgery is an independent predictor of changes in respiratory mechanics, whether the procedure is laparoscopic or open. Furthermore, we observed that postoperative decreases in VC, FEV 1 and MIP varied with the surgical approach, independent of the site of surgery. The more marked impairment of respiratory mechanics that follows open compared with laparoscopic cholecystectomy has been described consistently in other reports Pain score was a significant predictor of postoperative respiratory function, an effect that was not present when the surgical approach was accounted for, suggesting that differences in the effects of laparoscopic and open procedures may be related in part to differences in pain accompanying the two approaches. Postoperative pain as reflected in pain scores and analgesic requirement, has typically been reported to be milder after laparoscopic than after open cholecystectomy. 12,13 Relief of pain after upper abdominal procedures done with a variety of techniques, including epidural analgesia, has been associated with limited improvement in postoperative reductions in VC and functional residual capacity. 16 However, diaphragm dysfunction itself does not appear to be altered even with effective analgesia. 17 CONCLUSIONS Cholecystectomy and hysterectomy are limited surgical procedures that are not associated with generalized postoperative muscle weakness. The site of surgery and the surgical approach (laparoscopic versus open) influence postoperative respiratory mechanics, with changes being more marked after upper abdominal and open procedures. There is less pain after laparoscopic procedures, which may account in part for their less-marked effects on respiratory mechanics. References 1. Watters JM, Clancey SM, Moulton SB et al: Impaired recovery of strength in older patients after major abdominal surgery. Ann Surg 1993; 218: Klidjian AM, Foster KJ, Kammerling RM et al: Relation of anthropometric and dynamometric variables to serious postoperative complications. BMJ 1980; 281: Rochester DF: Tests of respiratory muscle function. [review] Clin Chest Med 1988; 9: Scott J, Huskisson EC: Graphic representation of pain. Pain 1976; 2: Maxwell A: Muscle power after surgery. [letter] Lancet 1980; 1: McCue J, Newham D: Postoperative muscle strength. Ann R Coll Surg Engl 1990; 72: Churchill ED, McNeil D: The reduction in vital capacity following operation. Surg Gynecol Obstet 1927; 44: Ali J, Weisel RD, Layug AB et al: Consequences of postoperative alterations in respiratory mechanics. Am J Surg 1974; 128: Ford GT, Whitelaw WA, Rosenal TW et al: Diaphragm function after upper CJS, Vol. 39, No. 4, August

5 KIMBERLEY, KIRKPATRICK, WATTERS abdominal surgery in humans. Am Rev Respir Dis 1983; 127: Road JD, Burgess KR, Whitelaw WA et al: Diaphragm function and respiratory response after upper abdominal surgery in dogs. J Appl Physiol 1984; 57: Erice F, Fox GS, Salib YM et al: Diaphragmatic function before and after laparoscopic cholecystectomy. Anesthesiology 1993; 79: McMahon AJ, Russell IT, Ramsay G et al: Laparoscopic and minilaparotomy cholecystectomy: a randomized trial comparing postoperative pain and pulmonary function. Surgery 1994; 115: Joris J, Cigarini I, Legrand M et al: Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy. Br J Anaesth 1992; 69: Mealy K, Gallagher H, Barry M et al: Physiological and metabolic responses to open and laparoscopic cholecystectomy. Br J Surg 1992; 79: Frazee RC, Roberts JW, Okeson GC et al: Open versus laparoscopic cholecystectomy. A comparison of postoperative pulmonary function. Ann Surg 1991; 213: Craig DB: Postoperative recovery of pulmonary function. [review] Anesth Analg 1981; 60: Simonneau G, Vivien A, Sartene R et al: Diaphragm dysfunction induced by upper abdominal surgery. Role of postoperative pain. Am Rev Respir Dis 1983; 128: Books Received Livres reçus This list is an acknowledgement of books received. It does not preclude review at a later date. Cette liste énumère les livres reçus. Elle n en exclut pas la critique à une date ultérieure. Atlas of Surgical Techniques. Steven G. Economou and Tasia S. Economou. 683 pp. Illust. W.B. Saunders $253. ISBN Cancer Surgery. James C. Harvey and Edward J. Beattie. 599 pp. Illust. W.B. Saunders $167. ISBN Giant Intracranial Aneurysms. Edited by Issam A. Awad and Daniel L. Barrow. 299 pp. Illust. American Association of Neurological Surgeons, Park Ridge, Ill $95 (US). ISBN Brenner & Rector s The Kidney. Volume I and Volume II. 5th edition. Edited by Barry M. Brenner pp. Illust. W.B. Saunders Company, Philadelphia; W.B $472 (two-volume set). ISBN (vol. 1) ; (vol. 2) ; (twovolume set) ISBN Pathology for the Surgeon. Peter M. Banks and William G. Kraybill. 392 pp. Illust. W.B. Saunders Company, Philadelphia; W.B. Saunders Canada, Toronto $ ISBN Surgery of the Chest. Volume I and Volume II. 6th edition. David C. Sabiston, Jr. and Frank C. Spencer pp (vol. 1) and 2174 pp (vol. 2). Illust. W.B. Saunders $428 (two-volume set). ISBN (vol. 1) ; (vol. 2) ; (twovolume set) Surgical Critical Care. John A. Weigelt and Frank R. Lewis, Jr. 458 pp. Illust. W.B. Saunders Company, Philadelphia; W.B. Saunders Canada, Toronto $138. ISBN Total Burn Care. Edited by D.N. Herndon. 597 pp. Illust. W.B. Saunders Company Ltd., London, UK; W.B. Saunders Company, Toronto $163. ISBN JCC, Vol. 39, N o 4, août 1996