Computer-derived equations for predicting survival postoperatively. Their usefulness and limitations

We used multivariate analysis to determine whether survival following perforations of the gastrointestinal tract could be accurately predicted from preoperative data. Of 12 variables tested, four were found to have predictive value. These were age, pulmonary disease, preoperative shock, and the attending surgeon. When these four variables were employed in a logistic regression equation on 42 patients, it correctly predicted which 21 patients died before leaving the hospital. To produce an equation useful for other hospitals, we recalculated it without the attending surgeon variable. Again, the equation was used to predict survival. The correlation of predicted vs observed outcome remained high, and, using a 2 x 2 chi 2 test, the correlation was significant. We then cross validated the three-variable model on data from a second hospital. The model accurately predicted the new data equally well. We believe that predictive models can identify risk factors in a variety of patient populations and can determine who is likely to benefit from specific treatment modalities.     

Small-diameter portacaval H-graft for variceal hemorrhage

This report describes the steps in the development of the concept of partial shunting from its earliest stages to the 8-mm-diameter portacaval H-graft. Sequentially decreasing the diameter of the graft from 20 mm did not seem to affect hepatic hemodynamics until the 10-mm-diameter graft was used. At this point, we began to see some patients maintain prograde portal flow. Further reduction in diameter gave a higher rate of patients with prograde flow. Postoperative flow patterns correlate with lower encephalopathy rates and better long-term survival. Important nuances of the operative technique as well as pre- and postoperative management are described.     

Impaired oxygenation of gastric mucosa in portal hypertension

Increased susceptibility to mucosal damage is a prominent feature of portal hypertensive gastropathy. Since the portal hypertensive gastric mucosa has extensive microvascular changes, we postulated that the increased sensitivity to mucosal damage could have an ischemic basis. We measured distribution of gastric serosal and mucosal oxygenation in a group of portal hypertensive and sham-operated rats, and then studied the effects of intragastric aspirin. In the basal state, gastric mucosa of portal hypertensive rats had significantly reduced oxygenation compared to controls (24±5 vs 45±7 mm Hg PO ₂,P < 0.02), while serosal oxygenation was similar between the two groups. Intragastric aspirin produced significantly greater mucosal damage to portal hypertensive rats and mucosal oxygenation was almost one third that of sham-operated controls. Systemic arterial pressures and oxygenation were similar between the two groups. We conclude that there is impairment of gastric mucosal oxygenation and increased mucosal damage by aspirin in portal hypertensive rats compared with sham-operated controls. These results support our hypothesis that the increased sensitivity of the portal hypertensive mucosa to damage is a consequence of impaired mucosal oxygenation.This study was supported by the Veterans Administration Research Service.This work was presented, in part, at the Plenary Session of the American Association for the Study of Liver Diseases, May 1988, New Orleans, Louisiana.     

Propranolol reduces ethanol-induced gastric mucosal damage in portal hypertensive rats

In a standardized rat model of portal hypertension, we investigated the effects of propranolol on alcohol-induced gastric mucosal damage. Portal hypertensive rats pretreated with 2 mg propranolol, compared with those receiving saline, had significantly reduced portal pressures (24 +/- 1 vs 32 +/- 1 cm saline), macroscopic mucosal damage (24 +/- 1 vs 39 +/- 4% of mucosa), and histologic deep necrosis (36 +/- 2 vs 61 +/- 4% of mucosal length). Increased dosage of propranolol to 4 mg did not produce any further reduction of portal pressure or mucosal damage. Central venous and systemic arterial pressures were not significantly altered by propranolol. The extent of mucosal damage correlated with levels of portal pressure (P less than 0.01) in portal hypertensive rats. Sham-operated normotensive rats had less macroscopic mucosal damage (26 +/- 4%) than portal hypertensive rats, and propranolol did not affect the extent of ethanol-induced damage or portal pressures in these animals. We conclude: (1) Propranolol is effective in reducing extent of ethanol-induced gastric mucosal damage in portal hypertensive rats, but not in sham-operated controls; (2) this effect correlates with reduction of portal pressure; and (3) our study supports the clinical impression that reducing portal pressure may be one approach for the prevention and therapy of gastric mucosal damage in portal hypertension.     

Retrograde Inversion Stripping as a Complication of the Clarivein? Mechanochemical Venous Ablation Procedure

The endovenous revolution has accelerated the development of new techniques and devices for the treatment of varicose veins. The ClariVein^® mechanochemical ablation device offers tumescentless treatment with a rotating ablation tip that can theoretically become stuck in tissue. We present the first report of retrograde stripping of the small saphenous vein without anaesthesia following attempted use of the ClariVein^® device, without adverse sequelae.     

Activation of eNOS in rat portal hypertensive gastric mucosa is mediated by TNF-alpha via the PI 3-kinase-Akt signaling pathway

Activation of endothelial nitric oxide synthase (eNOS) in portal hypertensive (PHT) gastric mucosa leads to hyperdynamic circulation and increased susceptibility to injury. However, the signaling mechanisms for eNOS activation in PHT gastric mucosa and the role of TNF-alpha in this signaling remain unknown. In PHT gastric mucosa we studied (1) eNOS phosphorylation (at serine 1177) required for its activation; (2) association of the phosphatidylinositol 3-kinase (PI 3-kinase), and its downstream effector Akt, with eNOS; and, (3) whether TNF-alpha neutralization affects eNOS phosphorylation and PI 3-kinase-Akt activation. To determine human relevance, we used human microvascular endothelial cells to examine directly whether TNF-alpha stimulates eNOS phosphorylation via PI 3-kinase. PHT gastric mucosa has significantly increased (1) eNOS phosphorylation at serine 1177 by 90% (P <.01); (2) membrane translocation (P <.05) and phosphorylation (P <.05) of p85 (regulatory subunit of PI 3-kinase) by 61% and 85%, respectively; (3) phosphorylation (P <.01) and activity (P <.01) of Akt by 40% and 52%, respectively; and (4) binding of Akt to eNOS by as much as 410% (P <.001). Neutralizing anti-TNF-alpha antibody significantly reduced p85 phosphorylation, phosphorylation and activity of Akt, and eNOS phosphorylation in PHT gastric mucosa to normal levels. Furthermore, TNF-alpha stimulated eNOS phosphorylation in human microvascular endothelial cells. In conclusion, these findings show that in PHT gastric mucosa, TNF-alpha stimulates eNOS phosphorylation at serine 1177 (required for its activation) via the PI 3-kinase-Akt signal transduction pathway.     

Admission inflammatory markers and isolation of a causative organism in patients with spontaneous spinal infection

Introduction

The purpose of this study was to investigate the significance of the inflammatory markers on admission in the isolation of a causative pathogen in patients with spinal infection. Spinal infection is treated frequently at spinal units and can encompass a broad range of clinical entities. Its diagnosis is often delayed because of the difficulty of identifying the responsible pathogen.

Methods

Patients with spinal infection treated in our institution over a period of eight years were identified and their notes studied retrospectively. Admission C-reactive protein (CRP), white cell count (WCC) as well as co-morbidities and mode of pathogen identification were recorded. Overall, 96 patients were included in the study.

Results

The CRP levels on admission were correlated significantly with the overall potential for isolation of a pathogen (p<0.0001) and positive biopsy cultures (p=0.0016). Admission WCC levels were associated significantly with the overall potential for isolation of a pathogen (p=0.0003) and positive biopsy cultures (p=0.0023). Both CRP and WCC levels were significantly negatively correlated with the duration of the preceding symptoms (p=0.0003 and p<0.0001 respectively). Delay in presentation was significantly negatively correlated with organism isolation (p=0.0001). Multivariate analyses identified the delay in presentation as the strongest independent variable for organism isolation (p=0.014) in cases of spontaneous spinal infection when compared with the admission CRP level (p=0.031) and WCC (p=0.056).

Conclusions

In spontaneous spinal infection, delay in presentation is the strongest independent variable for organism isolation. High inflammatory marker levels on admission are a useful prognostic marker for the overall potential of isolating a causative organism either by blood cultures or by biopsy in patients with negative blood cultures. Furthermore, the admission inflammatory marker levels allow for treating surgeons to counsel their patients of the likelihood of achieving a positive microbiological yield from biopsy.     

Comparative study of portacaval and mesocaval interposition shunts

Portacaval and mesocaval interposition shunts using vascular prosthetic grafts were compared in 37 cirrhotic patients without portal vein thrombosis who were operated on for previous or active variceal hemorrhage. Operative indications and severity of liver disease were similar in the two groups of patients having one or the other procedure. The major difference in results was that none of the 23 patients with portacaval H-graft shunts had rebleeding, while 4 of 14 had rebleeding from varices after mesocaval interposition shunting. This contributed to the higher operative mortality associated with the latter procedure. The index of operative difficulty, as judged by blood loss and length of operation, and postshunt encephalopathy rates were similar for both procedures. Thus, while the mesocaval interposition shunt offers none of the reported theoretical advantages over portacaval H-graft shunt, it does place patients at greater risk of postoperative variceal rehemorrhage. It is concluded that the portacaval interposition shunt, because of its effectiveness and technical expediency, may be the operation of choice in cirrhotic patients with bleeding varices who are not otherwise candidates for other procedures which reduce portal flow less drastically.     

Repair of incisional hernia

Because wound infection is a major cause of incisional hernia, the question posed is whether or not repairs of incisional hernias are at a higher risk for wound infection also. To answer this, we analyzed the incidence of wound infection after repair of incisional hernias during a 30 month period and compared it with the infection rate in all other clean procedures performed during the same period. All repairs of incisional hernias were performed upon patients with completely healed incisions without clinical signs of infection. Patients undergoing concomitant procedures upon the gastrointestinal tract were excluded. During the 30 month period, 995 clean operations were performed. In the 80 repairs of incisional hernias, there were 13 infections proved by culture, yielding an over-all infection rate of 16 per cent. In the remaining 915 clean procedures, there were 14 wound infections (1.5 per cent, p less than 0.0001). Of these 915 clean operations, 241 were repairs of inguinal hernias. Two infections occurred in this subgroup (0.8 per cent, p less than 0.0001, compared with repairs of incisional hernias). In patients undergoing repairs of incisional hernias with previously documented wound infections, 41 per cent had infected repairs. By comparison, only 12 per cent of patients without a prior infection had infections develop in the hernial repair (p less than 0.05). The infection rate for patients not receiving prophylactic antibiotics (21 per cent) was almost twice the rate for those receiving antibiotics (11 per cent), p = 0.07. We concluded that repair of incisional hernias has a significantly higher rate of infection than do other clean general surgical procedures. Herniorrhaphy of a wound that was previously infected is at a higher risk for reinfection, despite complete healing of the skin and absence of clinical signs of infection. Perioperative antibiotic prophylaxis may be indicated, but randomized studies are needed. For reporting and surveillance purposes, repairs of incisional hernias should not be classified as clean surgical procedures.