METABOLIC RESPONSE TO TOTAL HIP ARTHROPLASTY UNDER HYPOBARIC SUBARACHNOID OR GENERAL ANAESTHESIA

Transcription

1 Br. J. Anaesth. (1987), 59, METABOLIC RESPONSE TO TOTAL HIP ARTHROPLASTY UNDER HYPOBARIC SUBARACHNOID OR GENERAL ANAESTHESIA F. M. DAVIS, V. G. LAURENSON, J. LEWIS, J. E. WELLS AND W. J. GILLESPIE Major surgery or trauma is accompanied by enhanced sympathetic activity and the release of trophic hormones from the hypothalamus, and with a failure of the normal negative feedback mechanisms of hormonal control (Hall, 1985). This results in cardiovascular, metabolic and other perturbations collectively known as "the stress response to surgery". Although general anaesthetic agents per se may have differing effects on autonomic tone and the secretion of hormones, these changes are minor compared with the response to surgery, and modify that response only slightly (Derbyshire and Smith, 1984). Recent work has shown that extradural and subarachnoid anaesthesia can modify the response to lower abdominal and minor lower limb surgery (Engqvist et al., 1977; Pflug and Halter, 1981). Since it is known that the autonomic nervous system is involved in the activation of haemostasis (Small et al., 1984), modification of the neuroendocrine response to surgery by regional anaesthesia might alter the haemostatic response to surgery. We have reported differences in the intraoperative haemostatic response to total hip replacement surgery (THR) between subarachnoid and general anaesthesia (Davis et al., 1987). To see whether, in the same patients, the neuroendocrine response was also modified by subarachnoid anaesthesia, we studied the peri- F. M. DAVIS,* F.F.A.R.C.S., F.F.A.R.A.CS.; V. G. LAURENSON, F.F.A.R.A.CS.; J.LEWIS, PH.D.; J. E. WELLS, PH.D.; W. J. GILLESPIE, CH.M., F.R.A.C.S., F.R.CS.(ED.); Christchurch Clinical School of the University of Otago, Christchurch, New Zealand. Accepted for Publication: December 2, Present address, for correspondence: Department of Anaesthesia, Christchurch Hospital, Christchurch, New Zealand. SUMMARY Whole blood glucose concentration was estimated in 93 patients undergoing total hip arthroplasty under either subarachnoid or general anaesthesia. In 77, plasma cortisol concentration was also estimated before and after surgery. There were no preoperative differences between the two groups. Blood glucose concentration increased slightly following induction in both groups, but with spinal anaesthesia it decreased again, whereas with general anaesthesia it continued to increase (P < ). Plasma cortisol concentration with spinal anaesthesia was 291 (SD 145) nmol litre' 1 before, and 279 (253) nmol litre' 1 30 min after operation. With general anaesthesia there was a three-fold increase from 301 (159) nmol litre* 1 (preoperative) to 987 (474) nmol litre' 1 30 min after operation (P < ). Low spinal anaesthesia with a predominantly unilateral block appears sufficient to suppress the neuroendocrine response to hip surgery. operative changes in plasma cortisol and blood glucose concentrations during THR. PATIENTS, MATERIALS AND METHODS Patients One hundred and one patients gave written informed consent to the study, which was approved by the Hospital Ethical Committee. Of these, 93 provided venous blood samples for metabolic studies. Patients without a history of thromboembolic disease and presenting with osteoarthritis of the hip joint were studied.

2 726 BRITISH JOURNAL OF ANAESTHESIA Aspirin, if being taken, was stopped 1 week before, and other analgesics on the day before, surgery. The sexes were separately randomized to receive either subarachnoid anaesthesia (SAB group) or general anaesthesia (GA group). The characteristics of the two groups are summarized in table I. Clinical and anaesthetic management Diazepam 10 mg was given orally as premedication, 90 min before the operation. Before induction, antiembolism stockings (TED, Kendall) were put on, electrocardiographic and arterial pressure monitoring commenced and an i.v. infusion established. In the GA group, following fluid loading with acetated Ringer's solution, i.v. morphine 0.25 mg/kg body weight was given. Anaesthesia was induced with thiopentone, and neuromusailar blockade obtained with tubocurarine 0.5 mg kg" 1. The trachea was intubated and anaesthesia maintained with nitrous oxide in oxygen (2:1 ratio) with normocapnic intermittent positive pressure ventilation. Halothane, up to 1%, and incremental doses of tubocurarine were given as clinically indicated. At the end of surgery, any residual neuromuscular blockade was antagonized with neostigmine 2.5 mg (combined with atropine 1.2 mg). For subarachnoid anaesthesia, fluid loading was commenced and the patient positioned lying on the non-surgical side with 10 head-down tilt. The subarachnoid space was identified using a routine sterile midline or paramedian approach at either the 3rd or 4th lumbar space. Anaesthesia was induced with a hypobaric solution of 1 % amethocaine mg, in sterile water. Light basal sedation was provided with morphine followed by an infusion of 0.8 % chlormethiazole (Heminevrin). These patients breathed oxygenenriched air throughout surgery. The aim of both anaesthetic techniques was to achieve modest hypotension for surgery. An Exeter total hip arthroplasty was performed via the postero-lateral approach using a standard procedure without trochanteric osteotomy. Pressure injection of methylmethacrylate cement and a polyethylene femoral cement restrictor were used. During the operation the replacement of crystalloid and blood followed a strict regimen which was based on the duration of surgery, body weight, haematocrit and measured blood loss. Hypotension was managed with fluids and posturing alone. Vasoactive drugs were not used in the spinal anaesthetic solution or i.v. to manage hypotension so as to avoid any possible interference with the biochemical or haematological studies. In the SAB group, the height of the block on the surgical side was assessed, using temperature (cold) sensation, between 5 and 10 min following spinal injection, immediately before commencing the chlormethiazole infusion. This was to verify the adequacy of the block for surgery, rather than to provide accurate documentation of the spread of the block to its maximum extent. In the recovery room, at the end of surgery, the extent of blockade was again examined, when the ability to extend the knee against gravity and the presence or absence of light touch sensation in the L2/3 dermatome in both legs were noted. Blood sampling Venous blood samples were drawn from a fresh venepuncture site on four occasions: sample A = before induction of anaesthesia; sample B = 30 min after surgery started; sample C = 5 min after insertion of the femoral prosthesis; sample D = 30 min after the end of surgery. On each occasion, as well as the samples for haematological studies (Davis et al., 1987), 0.5 ml of blood was placed into a micro glucose tube containing heparin fluoride for estimation of glucose concentration. Citrated platelet-poor plasma from samples A and D was obtained by centrifugation at 2550 for 10 min at 4 C and stored at 20 C. Plasma cortisol concentration was estimated only if sufficient plasma was available for both this and the haematological tests. Glucose and cortisol assays Blood glucose concentration was measured using a standard automated immobilized hexokinase method (Technicon SMAC). The normal range for this laboratory is mmol litre" 1 (random). Plasma cortisol concentration was estimated using a recently developed direct enzyme-linked immunosorbent assay (ELISA) (Lewis and Elder, 1985). The plasma cortisol concentration was corrected for citrate dilution. The normal range ( h) for the assay in this laboratory is nmol litre" 1 (Lewis and Elder, 1985).

3 METABOLIC RESPONSE TO TOTAL HIP ARTHROPLASTY 727 Statistical analysis The biostatistics package BMDP (Dixon, 1981) was used for statistical analysis. Analysis of covariance, paired and unpaired Student's t tests and linear regression analyses were used, where appropriate. The Bonferroni correction with repeated comparisons was applied to the blood glucose results such that significance was assumed where a = RESULTS There were no clinical differences between the two groups before surgery (table I). Blood transfusion was commenced between samples C and D in four of the SAB group and 11 of the GA group (Chi-square = 4.7; P < 0.05). In the SAB group the degree of blockade was satisfactory throughout surgery in all but one patient who required light general anaesthesia for skin closure. At the time of the preoperative assessment the upper limit of blockade on the surgical side was between the LI and T6 dermatomes, two-thirds being at T10 or below. The majority of patients still had some motor function in the non-surgical limb immediately before surgery, but sensation on the non-surgical side was not tested. At the end of surgery 87 % of SAB patients were able to extend the knee against gravity and 76 % had light touch sensation in the non-surgical limb whereas dense sensory and motor blockade persisted on the surgical side in all but one patient. Plasma cortisol concentration Plasma from samples A and D was available for cortisol examination in 77 of the 101 patients. Plasma cortisol concentrations before, and after, surgery are shown in figure 1. There was no TABLE I. General data (mean, lsd)for 93 patients undergoing total hip arthroplasty under either spinal (SAB) or general (GA) anaesthesia. *P < 0.05 Patients Male Female Total Age (yr) Weight (kg) Surgical time (min) Patients transfused during operation SAB (8.4) 71.3(15.8) 70.4 (10.2) 4 GA (10.1) 69.2 (12.0) 74.4(17.6) 11* i? PI SAB GA Before After Before After operation operation FIG. 1. Plasma cortisol concentrations (mean, SEM) preinduction, and 30 min after surgery, in 77 patients undergoing total hip arthroplasty under either spinal (SAB, n = 38) or general (GA, n = 39) anaesthesia. See text for statistical analysis. difference between the groups before operation SAB group 291 (145) nmol litre" 1 ; GA group 301 (159) nmol litre" 1. In the SAB group the mean cortisol concentration did not change following surgery (279 (253) nmol litre" 1 ), whereas there was a three-fold increase in the GA group (987 (474) nmol litre" 1 ) (t = 10.93, P < ). There was no correlation between the extent of the spinal blockade just before surgery and the postoperative plasma cortisol concentration. Blood glucose concentration Data from all four samples A to D were obtained in 93 of the 101 patients studied. There was no difference between the two groups before induction (mean 5.3 (0.6) mmol litre" 1 ). The changes in blood glucose concentration are shown in figure 2. A slight increase was seen following the induction of anaesthesia in both groups. In the GA group blood glucose concentration continued to increase during surgery to achieve a mean value of 7.0 (1.1) mmol litre" 1 in the early postoperative period (sample D), whereas it decreased significantly following the surgical procedure in the SAB group (5.8 (0.9) mmol litre" 1 ) (analysis of covariance: Time, P < ; Anaesthesia, P = 0.18; Time- Anaesthesia interaction, P < ). There was a significant difference in blood glucose concentration between the two groups at sample D (f = 5.51; P < ). In the SAB group there was no correlation between the upper limit of the block as tested just before surgery and the blood

4 728 BRITISH JOURNAL OF ANAESTHESIA \ «H i -S 6.0^ c o ~ C» CO c? 5.0 Sample FIG. 2. Whole blood glucose concentrations (mean, SEM) in 93 patients during total hip arthroplasty under either spinal (SAB) or genera] (GA) anaesthesia. See text for timing of samples and statistical analysis. glucose concentration at sample B. There were no differences in blood glucose concentrations between patients in whom blood transfusion was started before sample D and those who did not receive blood during this time. DISCUSSION The hormonal changes and systemic responses to trauma are dependent on an intact afferent innervation of the site of injury. This was first demonstrated in a limb burn model in dogs under general anaesthesia (Egdahl, 1959), in which denervation of the limb before the injury blocked the responses completely. Even denervation subsequent to the injury resulted in significant modification of the neuroendocrine response in this model. In the clinical setting, extradural anaesthesia for abdominal hysterectomy has been shown to suppress the neuroendocrine response compared with general anaesthesia (Brandt et al., 1978), but this was only complete if the afferent blockade extended from T4 to S5 (Engqvist et al., 1977). In abdominal surgery, however, it is not only the extent of afferent blockade, but also the site and nature of the surgery that influences the metabolic response under regional anaesthesia. For instance, I D the cortisol response to upper abdominal surgery is not suppressed by segmental thoracic extradural blockade (Traynor et al., 1982), nor is that to Caesarean section by lumbar extradural blockade to T4 (Lindahl et al., 1983). The complex nature of the afferent innervation of the peritoneal cavity and its contents, combining autonomic (both sympathetic and parasympathetic) and somatic routes from widely different levels within the nervous system, presumably accounts for this marked variability. Subarachnoid and extradural anaesthesia might be expected to have different effects since, in the latter, systemic uptake of the local anaesthetic, and of any vasoconstrictor agent used, could have direct effects of their own. However, in abdominal hysterectomy, the effects of subarachnoid anaesthesia appeared to be indistinguishable from those previously reported for extradural anaesthesia when compared with general anaesthesia (Moller et al., 1984). It is clear from these studies that regional anaesthesia does not modify the neuroendocrine response in a consistent fashion, and that different types of surgery, therefore, require separate assessment of this effect. To study the neuroendocrine response to total hip replacement, and the haemostatic response (Davis et al., 1987) in the same patients, we compared subarachnoid, rather than extradural, anaesthesia with general anaesthesia in order to eliminate any systemic effects of the local anaesthetic agent. For the same reasons, vasoactive agents were not used in the spinal solution nor for the clinical management of any intraoperative hypotension. Plasma cortisol concentration was measured at 30 min after operation because the increase has consistently been reported to be approaching its maximum at about 1-2 h following the start of surgery (Brandt et al., 1978). In the present study there was complete suppression of the cortisol response in the SAB group despite the fact that the upper limit of blockade in the majority of patients would have been no more than lower thoracic. This is quite different from the responses to abdominal hysterectomy reported previously (Brandt et al., 1978; Engqvist et al., 1977), and is consistent with Egdahl's experiments (Egdahl, 1959). In a comparable study (Pflug and Halter, 1981), the neuroendocrine response to minor lower limb or perineal surgery involving minimal blood loss was studied in 34 patients under either general anaesthesia (with halothane) or spinal anaesthesia.

5 METABOLIC RESPONSE TO TOTAL HIP ARTHROPLASTY 729 Plasma cortisol concentration increased steadily with general anaesthesia to peak in the early postoperative period, but did not change in the patients undergoing subarachnoid blockade. Despite the considerably more major surgical trauma and blood loss of total hip replacement in our own study compared with these patients, the changes in plasma cortisol concentration in the two studies, with a three-fold increase in the GA group and no change in the SAB group, are almost identical. Blood glucose and adrenaline concentrations during and after surgery have been shown to correlate closely (Derbyshire and Smith, 1984). Pflug and Halter (1981) showed that there was a pronounced increase in plasma adrenaline concentration immediately following minor perineal or lower limb surgery under general anaesthesia, but that this did not occur following spinal anaesthesia. In the present study, an initial postinduction increase in blood glucose concentration occurred in both anaesthetic groups, suggesting that some sympathetic activation occurred over the pre-induction and induction period. This was transient in the SAB group and presumably related to the anxiety of undergoing a regional injection, whereas blood glucose concentration continued to increase in the GA group especially between samples C and D. The different patterns of change in blood glucose concentration observed in the present study in the two anaesthetic groups are consistent with the changes in adrenaline concentration reported in the patients studied by Pflug and Halter (1981). In the present study, the extent of the block tended to be quite low and predominantly unilateral such that sympathetic blockade was not likely to be extensive in the majority of patients. However, since the height of the block was only tested on the surgical side within 5-10 min of spinal injection, this will not necessarily reflect its final cephalad spread. It is not surprising, therefore, that no correlation was found between this recorded level and the changes in blood glucose concentration. The data presented in this study indicate that low hypobaric spinal anaesthesia with a predominantly unilateral block, unlike the extensive block required in lower abdominal surgery, is sufficient to suppress the plasma cortisol and blood glucose responses to total hip replacement. The modifications to the haemostatic response to hip surgery seen in these patients (Davis et al., 1987) are consistent with a difference in autonomic activity between the two anaesthetic techniques. Although, in patients undergoing abdominal hysterectomy (Rem et al., 1981), haemostatic changes have been reported to be independent of the neuroendocrine response to surgery, this may not be entirely the case with major lower limb surgery. This is presumably a result of the difference in autonomic innervation of the viscera of the peritoneal cavity compared with that of the tissues of the lower limb. REFERENCES Brandt, M. R., Fcrnandes, A., Mordhorst, R., and Kehlet, H. (1978). Epidural analgesia improves postoperative nitrogen balance. Br. Med. J., 1, Davis, F. M., McDermott, E., Hickton, C, Wells, E., Heaton, D. C, Laurenson, V. G., Gillespie, W. J., and Foate, J. (1987). Influence of spinal and general anaesthesia on haemostasis during total hip arthroplasty. Br. J. Anaesth., 59,561. Derbyshire, D. R., and Smith, G. (1984). Sympathoadrenal responses to anaesthesia and surgery. Br. J. Anaeith., 56, 725. Dixon, W. J. (ed.) (1981). BMDP Statistical Software. Berkeley: University of California Press. Egdahl, R. H. (1959). Pituitary-adrenal response following trauma to the isolated leg. Surgery, 46, 9. Engqvist, A., Brandt, M. R., Fernandes, A., and Kehlet, H. (1977). The blocking effect of epidural analgesia on the adrenocortical and hyperglycemic responses to surgery. Ada Anaetthesiol. Scand., 21, 330. Hall, G. M. (1985). The anaesthetic modification of the endocrine and metabolic response to surgery. Arm. R. Coll. Surg., 67, 25. Lewis, J. G., and Elder, P. A. (1985). An enzyme-linked immunosorbent assay (ELISA) for plasma cortisol. J. Steroid Biochem., 22, 673. Lindahl, S., Norden, N., Nybell-Lindahl, G., and Westgren, M. (1983). Endocrine stress response during general and eoiduraj anaesthesia for elective Caesarean sections. Ada Anaesthesiol. Scand., 27, 50. Moller, I. W., Hjortso, E., Krantz, T., Wandall, E., and Kehlet, H. (1984). The modifying effect of spinal anaesthesia on intra- and postoperative adrenocortical and hyperglycaemic response to surgery. Acta Anaeithesiol. Scand., 28, 266. Pflug, A. E., and Halter, J. B. (1981). Effect of spinal anaesthesia on adrenergic tone and the neuroendocrine responses to surgical stress in humans. Anestkesiobgy, 55, 120. Rem, J., Feddersen, C, Bradt, M. R., and Kehlet, H. (1981). Post-operative changes in coagulation and fibrinolysis are independent of neurogenic stimuli and adrenal hormones. Br.J.Surg., 68, 229. Small, M., Tweddel, A. C, Rankin, A. C, Lowe, G. D., Prentice, C. R., and Forbes, C. D. (1984). Blood coagulation and platelet function following maximal exercise: effects of beta-adrenoceptor blockade. Haemostasis, 14, 262. Traynor, C, Paterson, J. L., Ward, I. D., Morgan, M., and Hall, G. M. (1982). Effects of extradural analgesia and vagal blockade on the metabolic and endocrine response to upper abdominal surgery. Br. J. Anaesth., 54, 319.