Factors influencing length of hospital stay after primary total knee arthroplasty in a fast-track setting.

PURPOSE: The goal of this study was to identify factors prior to surgery that are associated with an increased length of hospital stay after TKA using a fast-track protocol. MATERIALS AND METHODS: In total, 879 consecutive patients who underwent primary TKA were included in this retrospective cohort study. A length of stay greater than or equal to three nights was considered an increased length of hospital stay. Univariable and multivariable generalized linear mixed models were used to identify potential factors associated with increased length of hospital stay. RESULTS: Length of hospital stay was significantly associated with age [OR 1.01 (95 % CI 1.01-1.02); p < 0.001], gender [female vs. male, OR 1.07 (95 % CI 1.00-1.15); p = 0.04], ASA [ASA III/IV vs. ASA I, OR 1.22 (95 % CI 1.06-1.39); p = 0.005], living situation (alone vs. together, OR 1.08 (95 % CI 1.00-1.16); p = 0.04], neurological comorbidities [OR 1.14 (95 % CI 1.06-1.23); p < 0.001], musculoskeletal comorbidities [OR 0.91 (95 % CI 0.85-0.97); p = 0.005], anaesthesia [spinal vs. general, OR 0.86 (95 % CI 0.76-0.97); p = 0.02], and weekday of surgery [Thursday vs. Monday, OR 1.12 (95 % CI 1.02-1.23); p = 0.02]. CONCLUSIONS: Older age, female gender, ASA III/IV, people living alone, the presence of neurological comorbidities, general anaesthesia and surgery on Thursday were associated with an increased length of hospital stay. In clinical practice, the knowledge of factors associated with an increased length of hospital stay can be used to further optimize peri-operative protocols for patients at risk for an increased length of hospital stay after TKA. LEVEL OF EVIDENCE: II.

Elastase is not sufficient to induce experimental abdominal aortic aneurysms.

PURPOSE: Research investigating abdominal aortic aneurysms (AAAs) commonly uses a rat model dependent on aortic infusion of porcine pancreatic elastase to initiate AAA formation. Unfortunately, the sizes of AAAs generated by this model have varied widely among published studies. This may reflect lot-to-lot variations in commercial elastase preparations. This study was undertaken to investigate the ability of different lots of elastase to induce AAAs and explain the variability identified. METHODS: Four lots of elastase were evaluated in the standard rat AAA model. Saline solution was used as a control. Additional groups of rats were treated with higher concentrations of elastase with or without the macrophage activator thioglycollate medium. Aortic diameters were measured in all rats. Inflammation and elastin degradation was examined histologically. Elastase activity and purity were evaluated for all lots. RESULTS: Of the four lots tested, only one was able to consistently generate AAAs at the standard dose (P <.05). Increasing the amount of elastase infused produced AAAs in some ineffective lots. Infusion of thioglycollate medium in combination with otherwise ineffective elastase produced AAAs (P =.02). However, the elastase with the highest purity failed to generate AAAs, even at the highest dose tested or in combination with thyioglycollate medium. Thioglycollate medium alone failed to result in AAA formation. All elastase lots displayed elastolytic activity in vitro and produced elastin degradation in vivo. Elastin degradation did not correlate with AAA size in elastase-treated rats (P = NS). Aneurysm size correlated with extent of inflammation (P =.005). CONCLUSION: Induction of AAAs does not correlate with elastolytic activity. Infusion of pure elastase alone is not sufficient to induce AAA formation in spite of evidence of elastin degradation. Presumed inflammatory modifiers, which contaminate some elastase preparations, enhance AAA formation. Future use of this rat model will need to take the variability of elastase preparations into account with controls for each new elastase lot.

Prophylactic inferior vena cava filters in trauma patients at high risk: follow-up examination and risk/benefit assessment.

PURPOSE: The efficacy of prophylactic inferior vena cava filters in selected trauma patients at high risk has come into question in relation to risk/benefit assessment. To evaluate the usefulness of prophylactic inferior vena cava filters, we reviewed our experience and overall complication rate. METHODS: From February 1991 to April 1998, the trauma registry identified 7333 admissions. One hundred eighty-seven prophylactic inferior vena cava filters were inserted. After the exclusion of 27 trauma-related deaths (none caused by thromboembolism), 160 patients were eligible for the study. The eligible patients were contacted and asked to complete a survey and return for a follow-up examination to include physical examination, Doppler scan study, vena cava duplex scanning, and fluoroscopic examination. The patients' hospital charts were reviewed in detail. The indications for prophylactic inferior vena cava filter insertion included prolonged immobilization with multiple injuries, closed head injury, pelvic fracture, spine fracture, multiple long bone fracture, and attending discretion. RESULTS: Of the 160 eligible patients, 127 were men, the mean age was 40.3 years, and the mean injury severity score was 26.1. The mean day of insertion was hospital day 6. Seventy-five patients (47%) returned for evaluation, with a mean follow-up period of 19.4 months after implantation (range, 7 to 60 months). On survey, patients had leg swelling (n = 27), lower extremity numbness (n = 14), shortness of breath (n = 9), chest pain (n = 7), and skin changes (n = 4). All the survey symptoms appeared to be attributable to patient injuries and not related to prophylactic inferior vena cava filter. Physical examination results revealed edema (n = 12) and skin changes (n = 2). Ten Doppler scan studies had results that were suggestive of venous insufficiency, nine of which had histories of deep vein thrombosis. With duplex scanning, 93% (70 of 75) of the vena cavas were visualized, and all were patent. Only 52% (39 of 75) of the prophylactic inferior vena cava filters were visualized with duplex scanning. All the prophylactic inferior vena cava filters were visualized with fluoroscopy, with no evidence of filter migration. Of the total 187 patients, 24 (12.8%) had deep vein thrombosis develop after prophylactic inferior vena cava filter insertion, including 10 of 75 (13.3%) in the follow-up group, and one patient had a nonfatal pulmonary embolism despite filter placement. Filter insertion complications occurred in 1.6% (three of 187) of patients and included one groin hematoma, one arteriovenous fistula, and one misplacement in the common iliac vein. CONCLUSION: This study's results show that prophylactic inferior vena cava filters can be placed safely with low morbidity and no attributable long-term disabilities. In this patient population with a high risk of pulmonary embolism, prophylactic inferior vena cava filters offered a 99.5% protection rate, with only one of 187 patients having a nonfatal pulmonary embolism.

Use of limited color-flow duplex for a carotid screening project.

BACKGROUND: Although the efficacy of carotid endarterectomy for asymptomatic carotid stenosis has been established, no cost-effective approach for identification of these patients has yet been devised. The purpose of this study was to develop a limited carotid duplex screening examination to be utilized for the detection of asymptomatic carotid stenoses. METHODS: Carotid screening examinations employed rapid identification of the carotid bifurcation using color-flow duplex imaging and an immediate Doppler-derived velocity of the segment of the internal carotid artery with the most turbulent flow. Complete examinations were then finished using well-established protocols in our accredited vascular laboratory. A total of 512 patients were referred for complete studies based upon standard indications. Criteria for at least a 50% internal carotid artery stenosis on the complete examination was defined as a peak systolic velocity (PSV) of at least 125 cm/sec. Receiver operator characteristic (ROC) curves were then constructed to identify the optimal screening velocity criteria as compared with the final results on the complete examination. RESULTS: Five screening examinations were technically limited yielding a total of 507 patients with 1,014 carotid arteries available for analysis. Comparison of screening examinations versus complete examinations for a PSV of 125 cm/sec yielded sensitivity 86%, specificity 98%, positive predictive value (PPV) 95%, and a negative predictive value (NPV) 93%. ROC analysis identified a "cut point" of 115 cm/sec on the screening examinations to achieve sensitivity 91%, specificity 95%, PPV 89%, and NPV 96%. Time to perform screening examinations averaged 3.2 minutes per patient. Three patients had common carotid lesions not identified on the limited internal carotid screening examinations. CONCLUSIONS: Screening carotid examinations are a rapid, reliable, and relatively inexpensive method for detection of patients with asymptomatic internal carotid artery stenosis. Limited screening examinations should be developed in each vascular laboratory and utilized in high-risk patients.

Factors associated with limb loss despite a patent infrainguinal bypass graft.

Lower-extremity limb salvage should parallel infrainguinal bypass graft patency. To determine factors associated with limb loss despite a patent bypass, we reviewed 191 consecutive infrainguinal bypasses in 158 patients followed prospectively over 42 months. In this series of 176 (92%) vein grafts, 15 (8%) expanded polytetrafluoroethylene grafts, 122 (64%) tibial artery bypasses, and 170 (89%) bypasses placed for limb salvage, 29 major lower-extremity (above-knee or below-knee) amputations were performed in 29 patients, 12 because of ischemia after graft thrombosis and 17 (9% of series) due to progression of soft tissue infection/necrosis despite a functioning bypass. Primary and secondary 36-month vein graft patencies by life-table analysis were 61 per cent and 81 per cent, respectively. When the 17 cases of limb loss were compared to the rest of the series, nonstatistically significant variables included male sex [11 (65%) vs 79 (56%); P = 0.608] and diabetes [12 (71%) vs 80 (57%); P = 0.310]. Statistically significant variables included black race [9 (53%) vs 39 (28%); P = 0.048]; chronic renal failure [6 (35%) vs 12 (9%); P = 0.005], placement to a tibial/pedal artery [15 (88%) vs 107 (62%); P = 0.034], distal anastomosis to the anterior tibial/dorsalis pedis (AT/DP) artery [8 (47%) vs 27 (16%); P = 0.004], and grafts requiring late revision [7 (41%) vs 22 (13%); P = 0.006]. Thirteen (76%) extremities had an intact pedal arch. Nine amputations were performed within 30 days (early group), and eight were performed from 45 days to 20 months (median, 8 months) after bypass placement (late group). The most common primary causes of limb loss in the early group were overwhelming progression of soft-tissue infection despite patent bypass (n = 4; 44%) and insufficient runoff in the foot (n = 3; 33%). In the late group, amputation most often followed long treatment of a chronic proximal diabetic neuropathic foot ulcer with osteomyelitis. Five (63%) grafts in this group were anastomosed to the AT/DP arteries. These data suggest that patients with chronic renal failure, chronic neuropathic heel ulcers, and an AT/DP bypass are at greater risk for amputation despite a working bypass, especially if the graft develops a hemodynamically significant stenosis. Careful judgment and patient selection under these circumstances are thus justified.