Martin S. Litwin

Influence of Surgical Subspecialty Training on in-Hospital Mortality for Gastrectomy and Colectomy Patients

Objective: This study examined the relationship of surgeon subspecialty training and interests to in-hospital mortality while controlling for both hospital and surgeon volume. Summary Background Data: The relationship between volume of surgical procedures and in-hospital mortality has been studied and shows an inverse relationship. Methods: A large Statewide Planning and Research Cooperative System was used to identify all 55,016 inpatients who underwent gastrectomy (n = 6434) or colectomy (n = 48,582) between January 1, 1998 and December 31, 2001. Surgical subspecialty training and interest was defined as surgeons who were members of the Society of Surgical Oncology (training/interest; n = 68) or the Society of Colorectal Surgery (training; n = 61) during the study period. The association of in-hospital mortality and subspecialty training/interest was examined using a logistic regression model, adjusting for demographics, comorbidities, insurance status, and hospital and surgeon volume. Results: Overall mortality for colectomy patients was 4.6%; the adjusted mortality rate for subspecialty versus nonsubspecialty-trained surgeons was 2.4% versus 4.8%, respectively (adjusted odds ratio [OR] = 0.45; 95% confidence interval [CI] = 0.34, 0.60; P < 0.0001). Gastrectomy patients experienced an overall mortality rate of 8.4%; the adjusted mortality rate for patients treated by subspecialty trained surgeons was 6.5%, while the adjusted mortality rate for nonsubspecialty trained surgeons was 8.7% (adjusted OR = 0.70; 95% CI = 0.46, 1.08; P = 0.10). Conclusions: For gastrectomies and colectomies, risk-adjusted mortality is substantially lower when performed by subspecialty interested and trained surgeons, even after accounting for hospital and surgeon volume and patient characteristics. These findings may have implications for surgical training programs and for regionalization of complex surgical procedures.

Pulmonary microembolism associated with massive transfusion: I. Physiologic effects and comparison in vivo of standard and dacron wool (swank) blood transfusion filters in its prevention.

Pulmonary microembolism of microaggregates associated with massive blood transfusion may be a cause of post-traumatic pulmonary embolism. The purpose of this study was to investigate in the dog the influence on certain physiologic parameters of transfusion of blood containing platelet: white blood cell: fibrin (PWF) aggregates and to evaluate the effects of using blood transfusion filters of varying pore sizes during such transfusions. Exchange transfusions of approximately twice blood volume were performed in three groups of animals. Screen filtration pressure measurements verified the presence of large numbers of PWF aggregates in the transfusions. When no transfusion filters or standard commercially available blood transfusion filters of pore size 170 mu were used, experimental animals developed pulmonary hypertension, a decrease in total body 92 consumption, and metabolic acidosis. Interposition of Dacron wool (Swank) blood transfusion filters prevented these changes.

Pulmonary microembolism associated with massive transfusion: II. The basic pathophysiology of its pulmonary effects.

In animals pulmonary hypertension, a decrease in total body O2 consumption and metabolic acidosis occur after transfusion of blood with an elevated screen filtration pressure (SFP) through standard blood transfusion filters. The purpose of this study was to define in detail the pulmonary abnormalities that develop following transfusion of blood with an elevated SFP through standard blood transfusion filters. Exchange transfusions of approximately twice blood volume were administered through standard commercially available blood transfusion filters (measured pore size--200 microns) to 6 animals. SFP measurements verified the presence of large numbers of aggregates in the transfusions. Although filters reduced SFP of the stored blood somewhat, numerous microaggregates passed the filters, and post-filtration SFP remained high. After transfusion average O2 consumption decreased to 77% of normal and metabolic acidosis developed. Pulmonary arterial hypertension was associated with an increase in pulmonary shunting of blood and a decrease in pulmonary diffusing capacity. The presence of extensive numbers of microemboli in the pulmonary arteriolar and capillary bed was confirmed by microscopic examination of lung tissue.

A Comparison In Vivo of Dacron Wool (Swank) and Polyester Mesh (Pall) Micropore Blood Transfusion Filters in the Prevention of Pulmonary Microembolism Associated with Massive Transfusion

Experiments were performed to compare the effectiveness in vivo of the two most widely used micropore blood transfusion filters in preventing detrimental physiologic changes associated with transfusion of microaggregate-containing blood. Exchange transfusion with stored blood having an elevated screen filtration pressure (SFP) through polyester mesh (Pall) filters (Group PM) was followed by decreases in arterial blood pH and O2 consumption, increases in arterial blood pyruvate and lactate concentrations, and a decrease in pulmonary DO2. The lungs of 5 of 6 animals revealed emboli far out in the pulmonary microcirculation. These changes did not occur in animals transfused through dacron wool (Swank) filters (Group DW). Even though an increase after transfusion in pulmonary Qs/Qt in Group PM did not achieve statistical significance when compared to pretransfusion Qs/Qt, it was significantly higher than that in animals in Group DW. Both filters removed considerable quantities of microaggregates; however, the polyester mesh (Pall) filters permitted passage of small microaggregates and development of ditrimental physiologic changes. Dacron wool (Swank) filters completely removed measurable microaggregates and detrimental changes did not occur.

Effect of Intravascular Cellular Aggregate Dissolution in Postoperative Patients

It was the purpose of this study to confirm whether the increase in packed cell (PC) viscosity that occurs in humans after elective surgery is accompanied by a decrease in total body O2 consumption as previously noted in animals, and further to define the effect of resolution of intravascular cellular aggregates (ICA) on these parameters. Thirty nine patients were studied. Total body O2 consumption was 76% of normal 6 hours postop, 81% of normal 24 hours postop and 87% of normal 48 hours postop. Twenty four hours after operation PC viscosity had increased markedly. Saline infusion had no significant effect on total body O2 consumption or PC viscosity, either pre- or postop. but WB viscosity decreased linearly in proportion to the drop in hematocrit. Resolution of ICA by dextran-40 infusion was associated with return of total body O2 consumption and PC viscosity to normal; a decrease in WB viscosity was disproportionately greater than would have been seen had the decrease been due solely to the drop in hematocrit. It is concluded that in humans surgical trauma causesan increase in PC viscosity and microcirculatory impairment as evidenced by a decrease in total body O2 consumption. Resolution of ICA by dextran-40 infusion reverses these detrimental changes.