One year results of a randomised controlled multi-centre study comparing Prolene and Vypro II-mesh in Lichtenstein hernioplasty.

A standard polypropylene mesh used in Lichtenstein's operation induces a strong foreign tissue reaction with potential harmful effects. A mesh with less polypropylene could possibly be beneficial. Six hundred men with primary unilateral inguinal hernias were randomised to Lichtenstein's operation using a Prolene- or Vypro II-mesh in six centres. The patients were blinded to which mesh they received. A validated questionnaire assessing recurrence and pain along with SF-36 Health Survey was sent after 1 year to all patients and a selected group was clinically examined. Of the 591 operated patients, 526 (89.0%) returned the questionnaire. 188 patients had some complaints or sensations of which 111 patients were clinically examined. The mean follow-up time was 13.6 (SD. 4.0) months. The incidence of hernia recurrence (four vs. four patients) and neuralgia (three vs. four patients) did not differ between Prolene and Vypro II-groups, respectively. One Vypro II-patient was re-operated due to neuralgia. There was no difference in the SF-36 scores. The results of Lichtenstein's operation with either Prolene or Vypro II do not seem to differ significantly.

Microdialysis of adipose tissue during surgery: effect of local alpha- and beta-adrenoceptor blockade on blood flow and lipolysis.

The adrenergic regulation of adipose tissue lipolysis and blood flow was investigated in nonobese patients (10 men and 23 women) undergoing cholecystectomy. Two microdialysis probes were inserted into the scadipose tissue and microdialyzed in the absence or presence of 10(-4) mol/L of either nonselective beta-adrenoceptor blocker propranolol or nonselective alpha-adrenoceptor blocker phentolamine. The catecholamines increased rapidly after intubation and subsequent surgery and extubation (P = 0.0001; F = 11-13). In the middle of surgery, the elevations of the noradrenaline and adrenaline levels were almost 3 times the basal value. At the end of surgery, they dropped in parallel, but increased again, only to reach their absolute maximum in connection with extubation (10- and 3-fold elevation, respectively). Plasma glycerol and free fatty acids started to increase about 30 min after plasma catecholamines. These increases in catecholamines were paralleled by an increase in the dialysate glycerol level (lipolysis index). Propranolol inhibited by two thirds (P = 0.003) and phentolamine further stimulated by 25% (P = 0.04) the increase in glycerol in the tissue dialysate induced by the operation. There was a transient decrease in tissue blood flow (ethanol escape from the microdialysis probe; P < 0.001) at the beginning of the surgical procedure. This was not affected by propranolol or phentolamine. In conclusion, during anesthesia and surgical trauma, endogenous catecholamines modulate adipose tissue lipolysis via alpha- and beta-adrenoceptors. However, the vasoconstriction induced by these procedures seems to be independent of the adrenergic system.

Evaluation of the microdialysis ethanol technique for monitoring of subcutaneous adipose tissue blood flow in humans.

OBJECTIVE: To investigate the feasibility of the microdialysis ethanol perfusion technique for monitoring nutritive blood flow in subcutaneous adipose tissue. RESEARCH DESIGN AND METHODS: Microdialysis probes were inserted percutaneously into the subcutaneous adipose tissue in 15 non-obese women, and were perfused with 50 mmol/l of ethanol. The experiments were carried out during basal conditions and in conjunction with local vasodilation induced by external heating. The ethanol exchange ratio (ethanol concentration in the outgoing tissue dialysate vs ethanol concentration in the ingoing perfusate) was determined. A comparison was made with the 133Xe clearance technique to assess the adipose tissue blood flow. RESULTS: At rest, the ethanol exchange ratio in the individual subjects was inversely correlated to the adipose tissue blood flow, as measured with 133Xe wash-out (r = -0.78-0.82, p < 0.05-0.01). When the subcutaneous temperature was increased in a stepwise fashion by external heating, adipose tissue blood flow, as determined with 133Xe clearance, was increased by about 50% and 100%, respectively, above resting values (F = 26.7, p < 0.0001). At the same time, the ethanol exchange ratio was progressively and significantly (F = 24.6, p < 0.0001) reduced. In the individual subjects there was a close negative correlation (r = -0.90-0.94) between the ethanol exchange ratios and the corresponding adipose tissue blood flow values, as measured by 133Xe clearance, in response to local vasodilation. CONCLUSION: The microdialysis ethanol perfusion technique provides a valid indicator of small changes within the physiological range in adipose tissue blood flow.

Influence of operation on glucose metabolism and lipolysis in human adipose tissue: a microdialysis study.

OBJECTIVE: To investigate the effect of an operation on metabolism in human adipose tissue. DESIGN: Open study. SETTING: Department of Surgery and the Research Centre at Huddinge Hospital. SUBJECTS: 13 non-obese patients who underwent elective cholecystectomy, and 5 control subjects. INTERVENTIONS: Microdialysis of the extracellular compartment of abdominal subcutaneous adipose tissue was done before, during and after a 45-minute intravenous infusion of 20 g glucose before, and one day after, the operation. MAIN OUTCOME MEASURES: Concentrations of glycerol, glucose, lactate and pyruvate in the tissue dialysate and in venous plasma. RESULTS: After operation, the baseline plasma insulin concentration doubled (p < 0.001) and the fasting glucose concentration rose from 4.4 (0.1) to 5.3 (0.2) mmol/l (p < 0.001). In response to the glucose infusion, the maximum increase in plasma insulin trebled (p < 0.01) and the integrated concentrations (area under the curve) of plasma glucose, lactate and pyruvate were significantly more pronounced (p < 0.02-p < 0.001) after than before operation. The suppression of plasma glycerol and free fatty acid concentrations was similar before and after operation (50-60%). The reduction in the concentrations of glycerol in adipose tissue, and the increases in the concentrations of glucose, lactate, and pyruvate, after intravenous infusion of glucose were not influenced by the operation. CONCLUSION: A moderately serious operation rapidly induces a deterioration in total body glucose homeostasis, partly as a result of peripheral insulin resistance. This does not affect the utilization of glucose by adipose tissue or the antilipolytic response to glucose infusion.

Lipolysis during abdominal surgery.

Subcutaneous adipose tissue lipolysis has been monitored with microdialysis during elective cholecystectomy by laparotomy in otherwise healthy nonobese subjects. Eight of the subjects received saline and seven received glucose iv during the operation. In both groups the glycerol level in the microdialysate (lipolysis index) started to increase steadily from the start of the general anesthesia until the abdominal wall was closed. Thereafter it leveled off and remained elevated until after extubation. Plasma glycerol started to rise after the surgical incision. The levels of noradrenaline and adrenaline, but not of insulin, glucagon, and cortisol in plasma, changed in parallel with that of glycerol in the microdialysate. The glycerol response in adipose tissue in the group receiving iv glucose was three times more marked than in the saline group (P = 0.01) in spite of marked hyperinsulinemia, but there was no difference between the groups in plasma glycerol response. The plasma noradrenaline response was 50% higher (P = 0.03) in the glucose group than in the saline group, but there was no difference between the groups in the plasma adrenaline, glucagon, or cortisol responses. Adipose tissue blood flow was measured by the escape of ethanol from the dialysis solvent into the extracellular space. It was constant throughout the experimental period in both groups. In conclusion, the lipolysis rate is accelerated during general anesthesia and abdominal surgery because of increased catecholamine production. Perioperative glucose infusion is associated with a further acceleration of the lipolytic rate in subcutaneous adipose tissue due to an additional activation of the sympathetic nervous activity that overrides the antilipolytic effect of the glucose-induced hyperinsulinemia. Other adipose regions may be less sensitive to glucose infusions and anesthesia.