Zeev Rotstein, MD, MHA, Rachel Wilf-Miron, MD, MPH, Bruno Lavi BA, Daniel S. Seidman, MD, MMSc, Poriah Shahaf, MD, MBA, Amir Shahar, MD, MPH, Uri Gabay, MD, MPH and Shlomo Noy, MD, MBA
Background: The emergency department is one of the hospital’s busiest facilities and is frequently described as a bottleneck. Management by constraint is a managerial methodology that helps to focus on the most critical issues by identifying such bottlenecks. Based on this theory, the benefit of adding medical staff may depend on whether or not physician availability is the bottleneck in the system.
Objective: To formulate a dynamic statistical model to forecast the need for allocating additional medical staff to improve the efficacy of work in the emergency department, taking into account patient volume.
Methods: The daily number of non-trauma admissions to the general ED was assessed for the period 1 January 1992 to 1 December 1995 using the hospital computerized database. The marginal benefit to shortening patient length of stay in the ED by adding a physician during the evening shift was examined for different patient volumes. Data were analyzed with the SAS software package using a Gross Linear Model.
Results: The addition of a physician to the ED staff from noon to midnight significantly shortened patient LOS: an average decrease of 6.61 minutes for 80–119 admissions (P<0.001). However, for less than 80 or more than 120 admissions, adding a physician did not have a significant effect on LOS in the ED.
Conclusions: The dynamic model formulated in this study shows that patient volume determines the effectiveness of investing manpower in the ED. Identifying bottleneck critical factors, as suggested by the theory of constraints, may be useful for planning and coordinating emergency services that operate under stressful and unpredictable conditions. Consideration of patient volume may also provide ED managers with a logical basis for staffing and resource allocation.
Alexander Kagan, MD, Nurit Haran, PhD, Ludmila Leschinsky, MD, PhD, Ruty Sarafian, RN, BA, Dan Aravot, MD, Jaffa Dolberg, RN, Ziv Ben-Ary, MD and Jason Rapoport, MB, BS, MRCP
Background: Leptin is a 16 kDa hormone synthesized by adipocytes and involved in body weight regulation.
Objectives: To determine serum leptin concentrations in heart, liver and kidney transplant recipients.
Methods: We investigated 57 patients: 18 male heart transplant recipients (age 25-69 years) at 1-66 months after transplantation, 6 female and 8 male liver transplant recipients (age 33-70) at 11-73 months after transplantation, and 10 female and 15 male kidney transplant recipients (age 20-61) at 3-138 months after transplantation. All recipients were receiving immunosuppressive therapy, including prednisone 0-20 mg/day, azathioprine 75-125 mg/day, cyclosporin 100-250 mg/day or tacrolimus 2-10 mg/day. The results were compared to those of 10 female and 10 male healthy controls. Morning serum concentrations of leptin were measured with a commercial radioimmunoassay (Linco Research Inc., USA), and serum insulin and cortisol levels were measured by radioimmunoassay.
Results: Patients (both men and women) after heart, liver and kidney transplantation exhibited significantly higher serum concentrations of leptin and leptin/body mass index ratios than controls. Serum leptin concentrations were significantly higher in women than in men and correlated very significantly with BMI in all cases. The multivariate stepwise analyses showed that among parameters including BMI, gender, age, time after transplantation, prednisone dose, hematocrit, serum concentrations of glucose, albumin, creatinine, cortisol and insulin, only BMI, gender, cortisol and insulin were significant independent determinants of serum leptin levels in these patients.
Conclusions: This is the first report showing that, in addition to body mass index and gender, basal cortisol and insulin levels affect the hyperleptinemia in transplant patients. The clinical relevance of hyperleptinemia in these patients will require further investigation.
Giselle Zandman-Goddard, MD and Sigal Tal, MD