Productivity in relation to organization of a surgical department: a retrospective observational study.

BACKGROUND: Responsible and efficient resource utilization are important factors in healthcare. The aim of this study was to investigate how total case time differs between two differently organized surgical departments. METHODS: This is a retrospective observational study of a cohort of patients undergoing elective surgery for breast cancer or malignant melanoma in a university hospital setting in Sweden. All patients were operated on by the same set of surgeons but in two different surgical departments: a general surgery (GS) and a cardiothoracic (CT) surgery department. Patients were selected to the two departments from a waiting list in the order of referral for surgery. The effect of being operated on at the CT department compared to the GS department was estimated by linear regression. RESULTS: The final study cohort comprised 349 patients in the GS department and 177 patients in the CT department. Both groups were similar regarding surgical procedures, American Society of Anesthesiologists' score, body mass index, age, sex, and the skill level of the operating surgeon. These covariates were included in the linear regression model. The total case time, defined by the Procedural Time Glossary as room set-up start to room clean-up finish, was significantly shorter for the patients who underwent a surgical procedure at the CT department compared to the GS department, even after adjusting for the background characteristics of the patients and surgeon. After adjusting for the selected covariates, the average difference in total case time between the two departments was - 30.67 min (p = 0.001). CONCLUSIONS: A significantly shorter total case time was measured for operations in the CT department. Plausible explanations may be more beneficial organizational factors, such as staffing ratio, skill mix in the operating room team, and working behavioral aspects regarding resource utilization.

Endogenous gas formation--an in vitro study with relevance to gas microemboli during cardiopulmonary bypass.

UNLABELLED: Gas embolism is an identified problem during cardiopulmonary bypass (CPB). Our aim was to analyze the potential influence from gas solubility based on simple physical laws, here called endogenous gas embolism. Gas solubility decreases at higher temperature and gas bubbles are presumably formed at CPB warming. An experimental model to measure gas release was designed. Medium (water or blood retrieved from mediastinal drains, 14.6 mL) was incubated and equilibrated with gas (air, 100% oxygen, or 5% carbon dioxide in air) at low temperature (10 degrees C or 23 degrees C). At warming to 37 degrees C, gas release was digitally measured. Also, the effect of fluid motion was evaluated. At warming, the medium became oversaturated with dissolved gas. When fluid motion was applied, gas was released to form bubbles. This was exemplified by a gas release of .45% (.31/.54, medians and quartile range, volume percent, p = .007) and 1.26% (1.14/ 1.33, p = .003) when blood was warmed from 23 degrees C or 10 degrees C to 37 degrees C, respectively (carbon dioxide 5% in air). Consistent findings were seen for water and with the other types of gas exposure. The theory of endogenous gas embolization was confirmed with gas being released at warming. The endogenous gas formation demonstrated a dynamic pattern with oversaturation and with rapid gas released at fluid motion. The gas release at warming was substantial, in particular when the results were extrapolated to full-scale CPB conditions. The interference from endogenous gas formation should be considered in parallel to external sources of gas microemboli. KEYWORDS: cardiopulmonary bypass, gas embolization, microemboli, gas solubility, temperature.

A closed perfusion system with heparin coating and centrifugal pump improves cardiopulmonary bypass biocompatibility in elderly patients.

BACKGROUND: Cardiopulmonary bypass induces a systemic inflammatory and hemostatic activation, which may contribute to postoperative complications. Our aim was to compare the inflammatory response, coagulation, and fibrinolytic activation between two different perfusion systems: one theoretically more biocompatible with a closed-circuit, complete heparin coating, and a centrifugal pump, and one conventional system with uncoated circuit, roller pump, and a hard-shell venous reservoir. METHODS: Forty-one elderly patients (mean age, 73 +/- 1 years, 66% men) undergoing coronary artery bypass grafting or aortic valve replacement were included in a prospective, randomized study. Plasma concentrations of complement factors (C3a, C4d, Bb, and sC5b-9), proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-8), granulocyte degradation products (polymorphonuclear elastase), and markers of coagulation (thrombin-antithrombin) and fibrinolysis (D-dimer, tissue plasminogen activator antigen and tissue plasminogen activator-plasminogen activator inhibitor-1 complex) were measured preoperatively, at bypass during rewarming (35 degrees C), 60 minutes after bypass, and on day 1 after surgery. RESULTS: The mean concentrations of C3a (-39%; p = 0.008), Bb (-38%; p < 0.001), sC5b-9 (-70%; p < 0.001), interleukin-8 (-60%; p = 0.009), polymorphonuclear-elastase (-55%; p < 0.003), and tissue plasminogen activator antigen (-51%; p = 0.012) were all significantly lower in the biocompatible group during rewarming. Sixty minutes after bypass, the mean concentrations of sC5b-9 (-39%; p = 0.006) and polymorphonuclear-elastase (-55%; p < 0.001) were lower in the biocompatible group. CONCLUSIONS: The results suggest that a closed perfusion system with a heparin-coated circuit and a centrifugal pump may improve cardiopulmonary bypass biocompatibility in elderly cardiac surgery patients in comparison with a conventional system.

Regional oxygenation and systemic inflammatory response during cardiopulmonary bypass: influence of temperature and blood flow variations.

OBJECTIVE: To evaluate the role of target temperature (28 degrees or 34 degrees C) in cardiac surgery on regional oxygenation during hypothermia and rewarming and systemic inflammatory response. DESIGN: Prospective, controlled, and randomized clinical study. SETTING: University hospital. PARTICIPANTS: Elderly patients (mean age 70 +/- 2 years) with acquired heart disease with an anticipated bypass time exceeding 120 minutes (n = 30). INTERVENTIONS: The patients were cooled to either 28 degrees C (n = 15) or 34 degrees C (n = 15). At hypothermia, bypass blood flow was reduced twice from full flow (2.4 L/min/m(2) body surface area [BSA]) to 2.0 L/min/m(2). MEASUREMENTS AND MAIN RESULTS: Hepatic and jugular venous oxygen tension and saturation were higher at 28 degrees C than at 34 degrees C. In comparison with the preoperative values, at 28 degrees C hepatic venous values were higher; whereas at 34 degrees C, they were lower. The reduction of pump blood flow during hypothermia, from 2.4 to 2.0 L/min/m(2)was accompanied by reductions of central, jugular, and hepatic oxygenation at both target temperatures. During rewarming, central and regional venous oxygenation decreased irrespective of the preceding temperature. The decrease was most pronounced in hepatic venous blood, with the lowest individual values <10%. Serum concentrations of C3a and IL-6 increased during hypothermia and increased further during rewarming irrespective of the preceding temperature. CONCLUSION: During cardiopulmonary bypass, hypothermia at 28 degrees C increases regional and central venous oxygenation better than at 34 degrees C. In contrast, venous oxygenation decreases during rewarming irrespective of the preceding temperature. No significant difference in the systemic inflammatory response associated with target temperature was detected.

Influence of two different perfusion systems on inflammatory response in pediatric heart surgery.

BACKGROUND: This study tests the hypothesis that a cardiopulmonary bypass system that combines complete heparin-coating, a centrifugal pump, and a closed circuit in comparison with a conventional system (uncoated system, roller pump, and hard shell venous reservoir) attenuates the inflammatory response in pediatric heart surgery. METHODS: In a prospective randomized controlled clinical study 40 consecutive children weighing 10 kg or less were included and divided into two groups. Concentrations of complement proteins (C3a, sC5b-9, C4d, and Bb), granulocyte degranulation products (polymorphonuclear [PMN] elastase), and proinflammatory cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, and IL-8) were measured. RESULTS: C3a and sC5b-9 concentrations were lower (C3a, p < 0.001; sC5b-9, p = 0.01) in the combined (heparin-coated/centrifugal pump/closed reservoir) group, the peak values being 58% and 37% of conventional group values. The Bb- and C4d-fragment values indicated activation of the complement system through the alternative pathway in both groups. PMN elastase concentrations were lower (p = 0.02) in the combined group, the peak values being 43% of conventional group values. There were no significant intergroup differences regarding TNF-alpha, IL-6, or IL-8 concentrations. CONCLUSIONS: The use of a fully heparin-coated system, a centrifugal pump, and a closed circuit during CPB in children (10 kg or less) leads to a lower degree of complement activation and PMN elastase release compared with a conventional system.

The relationship between mixed venous and regional venous oxygen saturation during cardiopulmonary bypass.

The relationship between mixed venous and regional venous saturation during cardiopulmonary bypass (CPB), and whether this relationship is influenced by temperature, has been incompletely elucidated. Thirty patients undergoing valve and/or coronary surgery were included in a prospective, controlled and randomized study. The patients were allocated to two groups: a hypothermic group (28 degrees C) and a tepid group (34 degrees C). Blood gases were analysed in blood from the hepatic vein and the jugular vein and from mixed venous blood collected before surgery, during hypothermia, during rewarming, and 30 min after CPB was discontinued. Oxygen saturation in the hepatic vein was lower than in the mixed venous blood at all times of measurement (-24.0 +/- 3.0% during hypothermia, -36.5 +/- 2.9% during rewarming, and -30.5 +/- 3.0% postoperatively, p < 0.001 at all time points). In 23% of the measurements, the hepatic saturation was <25% in spite of normal (>60%) mixed venous saturation. There was a statistical correlation between mixed venous and hepatic vein oxygen saturation (r=0.76, p < 0.0001). Jugular vein oxygen saturation was lower than mixed venous saturation in all three measurements (-21.6 +/- 1.9% during hypothermia, p < 0.001; -16.7 +/- 1.9% during rewarming, p < 0.001; and -5.6 +/- 2.2% postoperatively, p = 0.037). No significant correlation in oxygen saturation could be detected between mixed venous and jugular vein blood (r = 0.06, p = 0.65). Systemic temperature did not influence the differences in oxygen saturation between mixed venous and regional venous blood at any time point. In conclusion, regional deoxygenation occurs during CPB, in spite of normal mixed venous saturation. Mixed venous oxygen saturation correlates with hepatic, but not with jugular, vein saturation. The level of hypothermia does not influence differences in oxygen saturation between mixed venous and regional venous blood.