Perioperative use of the LiMON method of indocyanine green elimination measurement for the prediction and early detection of post-hepatectomy liver failure.

INTRODUCTION: A non-invasive liver function monitoring system, the LiMON, has been developed that measures indocyanine green (ICG) elimination by pulse spectrophotometry. The aim was to assess the relationship between pre and post-operative ICG plasma disappearance rate (ICG PDR %/min) values and the onset of post-hepatectomy liver dysfunction. METHODS: 37 patients scheduled for major liver resections were selected. None had chronic liver disease. IGC PDR was measured preoperatively and on days 1, five and 10 postoperatively. On the same day, serum liver function tests were measured. RESULTS: The median preoperative and post-operative day 1 ICG PDR for the patients who developed liver dysfunction was significantly lower compared to those who did not (p=0.044, p=0.014). Significant correlation was found between ICG PDR measurement taken on postoperative day 1 and bilirubin level on day 1 (p=0.002), 5 (p=<0.001) and 10 (p=0.001). The same was true for ICG PDR on post-operative day 1 and albumin level on day 5 and 10 (p=0.003, p<0.001). DISCUSSION: LiMON ICG PDR measured by pulse spectophotometry is a quick, non-invasive and reliable liver function test in patients undergoing liver resection that aids in the prediction and early detection of post-hepatectomy liver dysfunction.

Correlation between blood loss and inferior vena caval pressure during liver resection.

BACKGROUND: Blood loss and transfusion requirement are major determinants of mortality and morbidity following liver resection. This study was prompted by the observation that blood loss was excessive when the inferior vena cava (IVC) was distended, and determined whether a correlation exists between blood loss and pressure within the IVC during liver resection. METHODS: A 6-month prospective study was conducted on 20 consecutive patients undergoing liver resection in which two variables were measured, the pressure within the retrohepatic part of the IVC and blood loss during resection. RESULTS: It was observed that when the caval pressure was less than 6 mmHg the operating field was almost bloodless (mean blood loss 363 (range 305-465) ml). When the caval pressure was between 6 and 12 mmHg the liver became congested and bleeding from the liver surface became significantly greater (1259 (range 415-1789) ml). When caval pressure was greater than 13 mmHg bleeding became excessive (2703 (range 2360-3450) ml). Correlation between blood loss and caval pressure was strong (Pearson correlation coefficient 0.93, P < 0.001). CONCLUSION: This study suggests that one of the keys to decreasing blood loss and transfusion requirement during liver resection is to lower pressure within the IVC.

Surgical decompression for thoracic outlet syndrome.

Fifty consecutive surgical decompression operations for thoracic outlet syndrome (TOS) were performed in 43 patients over a 7-year period. Of these, 54% presented with neurological symptoms alone; the others complained of symptoms of vascular or combined origin. Operations for decompression consisted of excisions of 14 cervical ribs, 22 first ribs, and 14 soft tissue or fibrous bands. In six limbs, cervical sympathectomy was also performed for patients who had secondary Raynaud's phenomenon. Surgery resulted in complete relief of symptoms in 37 limbs (74%) and an improvement was achieved in another 10 (20%). In three limbs (6%) surgery gave no benefit. There was no mortality. Thoracic outlet decompression via the supraclavicular approach gave good results in 94% of the patients.

Anergy, immunosuppressive serum, and impaired lymphocyte blastogenesis in burn patients.

Skin testing with four recall antigens was performed serially in 21 patients after a major thermal burn. We looked for a correlation between the occurrence of anergy, the presence of immunosuppressive serum, and the impairment of the lymphocyte-proliferative response to phytohemagglutinin (PHA). Serum cortisol, endotoxin, and prostaglandin E2 (PGE2) levels were also measured in the serum or plasma. When anergy developed, it became apparent early in the course of the illness. It did not correlate closely with the severity of the burn, but was associated with mortality. There was a good correlation between anergy and coexisting serum suppression of lymphocyte activation in vitro. This serum immunosuppressive activity was not related to serum cortisol, PGE2, or plasma endotoxin levels. Anergy also correlated with coexistent impairment of patient peripheral blood lymphocyte activation by PHA. These results suggest that both immunosuppressive serum and an impaired lymphocyte response to mitogens are associated with anergy in burn patients and confirm that the development of anergy is an index of poor prognosis.

Generation of suppressor cells in mice after surgical trauma.

Immunoincompetency is often seen in patients after various types of trauma and is associated with increased morbidity and mortality from infectious complications. To understand better the immunologic impairment associated with trauma, we have studied this phenomenon in an animal model. Splenocytes from mice traumatized by amputation of their right hind limbs were consistently shown to have a diminished capacity to proliferate in response to alloantigens and to form alloreactive cytolytic cells in mixed lymphocyte cultures. Anesthesia itself had no effect in this system. The immunoincompetency was detected from 2 h to 6 d after surgical trauma and was completely reversed by removing adherent and phagocytic cells from the splenocytes. Furthermore, addition of splenocytes from traumatized mice to mixed lymphocyte cultures from normal mice prevented normal lymphocytes from responding to alloantigens, suggesting the existence of suppressor cells. The suppressor cells were found to adhere to glass and to nylon wool columns, and were contained within an esterase-positive cell population. They were insensitive to treatment with anti-Thy 1.2 and anti-Ig sera in the presence of complement. Therefore, the present results suggest that a Thy 1.2-negative, Ig-negative, esterase-positive cell population capable of adhering to glass and nylon wool, presumably macrophages, was responsible for the inhibition of the responsiveness of lymphocytes to alloantigens in traumatized animals.

The relationship between the blood and vein wall fibrinolytic activities in response to surgical trauma.

The fibrinolytic response to surgical trauma was studied longitudinally in 7 pigs by measuring the fibrinolytic activity in the blood and vein wall simultaneously. The results indicated a marked suppression in fibrinolytic activity in the blood which was closely correlated with the activity in the vein wall. This correlation lends support to the hypothesis that the venous endothelium is the source of spontaneous fibrinolytic activity in the blood.

The fibrinolytic activity of the vein following venous stasis.

This animal study investigated the fibrinolytic activity in the vein wall of the pig following venous stasis, which was induced artificially using an intermittently inflated pneumatic cuff. The method used to measure the fibrinolytic activity was modified from Todd's original technique. The area of lysis and the area of the vein wall were measured and expressed as a ratio, called the fibrinolytic index. After 3 h of intermittent venous stasis the fibrinolytic index was reduced by 68 per cent, significantly lower than the control group. The reduction of the fibrinolytic index by venous stasis could play an important part in the development of deep vein thrombosis.

Correlation between anergy and a circulating immunosuppressive factor following major surgical trauma.

In order to clarify the relationship between anergy and immunosuppressive activity in the serum, we studied 46 previously well patients before and at three, five, seven and 28 days after surgery. Delayed hypersensitivity was measured by skin testing with four common recall antigens, and serum immunosuppressive activity was determined by the ability of the patient's serum in 10% concentration to suppress by 50% or more the phytohemagglutinin (PHA) stimulation of normal human lymphocytes as compared to pooled normal serum. Prior to surgery, all patients manifested delayed hypersensitivity to one or more antigens, and no patient had immunosuppressive serum. Fifteen patients underwent minor surgery under general anesthesia and did not develop anergy or immunosuppressive serum. Thirty-one patients underwent major cardiovascular surgery. Thirteen of these patients became anergic by day 3 after operation, and 11 of the 13 developed immunosuppressive serum. Eighteen patients maintained delayed hypersensitivity after major surgery, and only three developed immunosuppressive serum. The correlation between anergy and immunosuppressive serum was highly significant (p < 0.001). There was a significant difference in the degree of suppressive activity in the serum of the anergic and reactive patient groups for each postoperative day studied until day 28, when there was recovery of delayed hypersensitivity and lack of immunosuppressive serum. The occurrence of postoperative anergy and immunosuppressive serum was not related to the patient's age, sex, number of perioperative blood transfusions or duration of anesthesia but was associated with an increase in postoperative infectious complications (p < 0.05) and in postoperative days in the hospital (p < 0.01). Pooled immunosuppressive serum from anergic patients was fractionated by ion exchange chromatography, gel filtration and preparative high voltage electrophoresis. The majority of the immunosuppressive activity could be accounted for by an electrophoretically homogenous polypeptide-containing fraction not identified in the serum of patients undergoing minor surgery or in normal individuals. We conclude that anergy occurring after major operative trauma is associated with the appearance of a circulating immunosuppressive molecular species and that these events are in turn associated with increased patient morbidity and increased length of hospitalization.