Performance of low-dose cosyntropin stimulation test in the afternoon.

BACKGROUND: Earlier research on 1 µg low-dose test (LDT) performed using 20.3 cm plastic IV tubing on healthy volunteers, has shown that afternoon testing was associated with a sevenfold increased likelihood of failing the test. Nevertheless, it has been claimed that subnormal cortisol response using plastic tubes might have resulted from cosyntropin adherence to the tube and, thus, loss of the delivered dosage. Following from our previous study, which showed that using a short (2.5 cm) plastic tube does not alter in-vitro-cosyntropin dosage delivery or healthy-volunteers' morning cortisol responses, we predicted that, when using the same short plastic tube, LDT would show comparable morning and afternoon cortisol stimulation. The current study was designed to investigate this prediction by comparing morning and afternoon cortisol responses in healthy volunteers during LDT, using a short plastic tube. METHODS: Thirteen healthy adult volunteers were recruited for the study. Each subject underwent morning and afternoon LDT via 25 mm plastic intravenous line tube. Baseline serum cortisol (SC) in addition to SC and salivary free cortisol (SFC) 30-minute responses were determined. RESULTS: Mean baseline morning SC concentration was higher in the morning than in the afternoon (13.63±3.42 and 9.18±2.78 µg/dL, respectively; P<0.001); however, mean absolute SC-concentration increment between baseline and 30-minute time point was higher in the afternoon than in the morning (11.89±3.50 and 7.71±3.12 µg/dL, respectively; P=0.002). Subsequently, LDT resulted in comparable morning and afternoon 30-minute SC (21.33±3.08 and 21.08±3.43 µg/dL, respectively; P=0.782) and SFC concentration (0.939±0.256 and 1.036±0.372 µg/dL, respectively; P=0.463). CONCLUSIONS: In healthy volunteers, using a 2.5 cm plastic tube, LDT provides comparable morning and afternoon 30-minute stimulated SC and SFC concentration.

Performance of low-dose cosyntropin stimulation test handled via plastic tube.

PURPOSE: Studies on 1 µg low-dose test showed that among 1 µg cosyntropin samples pushed through long IV plastic tubing, some adrenocorticotropic hormone dosage was not recovered, and in healthy volunteers it provided subnormal cortisol responses. The aim of the current study is to assess whether there is any loss in adrenocorticotropic hormone 1-24 concentration when pushed through a short plastic tube, and to assess serum and salivary cortisol responses in low-dose test among healthy volunteers, using a similar short plastic tube vs. direct intravenous consyntropin injection. METHODS: We evaluated in vitro if adrenocorticotropic hormone was absorbed in a 2.5 cm plastic tube by measuring adrenocorticotropic hormone 1-24 concentration in a 1 µg/ml adrenocorticotropic hormone aliquot solution before and after being flushed through the plastic tube. For the in vivo study, we recruited 20 healthy adult volunteers. Each subject underwent low-dose test via 2.5 cm plastic tube via plastic tube and via direct intravenous injection by a metal syringe via direct intravenous injection, and cortisol responses were determined. RESULTS: Mean adrenocorticotropic hormone 1-24 concentration did not differ significantly when flushed via plastic tube or measured in the aliquot solution (P = 0.25). In vivo, mean 30-min serum cortisol concentrations were 20.47 ± 2.87 and 21.62 ± 3.89 µg/dl in via plastic tube and in via direct intravenous injection tests, respectively, and did not show a significant difference (P = 0.16). CONCLUSIONS: In low-dose test, using a 2.5 cm plastic tube ensures completeness of the intravenous adrenocorticotropic hormone injection dosage and provides equivalent cortisol responses.

Use of three-dimensional fluoroscopy to determine intra-articular screw penetration in proximal humeral fracture model.

BACKGROUND: Proximal humeral locking plates have significantly improved the treatment of proximal humeral fractures in recent years; however, they are not devoid of complications. Inadvertent screw penetration into the joint is a well-documented complication. Intraoperative 3-dimensional (3D) imaging may assist in detecting intra-articular implant penetration. This study compared the performance of a standard C-arm fluoroscope with a novel 3D imaging fluoroscope in detecting penetrating implants in a proximal humeral fracture model. METHODS: Zinc-sprayed proximal humerus sawbones were affixed with a proximal humeral locking plate. Six different constructs were assembled. In each specimen, 1 screw, 2 screws, or no screws were inserted 2-mm proud of the articular surface. Each specimen was imaged with a conventional fluoroscope and a 3D imaging fluoroscope. Overall, 36 image sets were prepared for each modality. These were evaluated by 2 fellowship-trained surgeons for intraobserver and interobserver reliability as well for the accuracy of detecting prominent implants in the 2 imaging methods. RESULTS: Overall accuracy for observer A was 89.9% compared with 100% for C-arm fluoroscopy and 3D imaging fluoroscopy (P < .01) and for observer B was 91.1% and 100% (P = .01), respectively. The κ values were 0.74 with C-arm fluoroscopy and 1.0 for the 3D imaging fluoroscopy for observer A, and 0.93 and 1.0, respectively, for observer B. CONCLUSIONS: In a proximal humeral fracture model, C-arm fluoroscopy is a highly accurate imaging modality that can minimize the incidence of penetrating screws into the joint. Further clinical studies are required to establish this modality.