Wrist Extension Does Not Change the Position of the Radial Artery: Cadaveric Study With Application to Arterial Line Placement, and Transradial Neurointerventional Procedures.

BACKGROUND: The radial artery is gaining popularity as a vascular access site for neurointerventional procedures. However, recent analyses of wrist position and radial artery anatomy has suggested that the extended position of the wrist is not always necessary. Therefore, the following cadaveric study was performed to verify these findings. METHODS: Twenty adult cadaveric upper limbs underwent dissection of the radial artery. The radial artery was exposed but left in its anatomical position. With the hand supinated, the wrist was extended to 45 degrees and 90 degrees. Observations were then made of any movement of the artery during these ranges of motion. Next, a tension gauge was attached to the radial artery and any tension on the artery measured during the above noted ranges of motion. RESULTS: During extension of the wrist, none of the radial artery specimens was found to move in any direction. Moreover, an average of only 0.28 N of tension on the artery was found with wrist extension up to 90 degrees. Our cadaveric study found that, contrary to popular belief, extension of the wrist during cannulation of the radial artery does not change the position of the artery nor does it significantly alter the tension on the artery. CONCLUSIONS: These data support several recent clinical studies.

Hypocapnia, ischemic lesions, and outcomes after intracerebral hemorrhage.

BACKGROUND: An association between spontaneous hyperventilation, delayed cerebral ischemia, and poor clinical outcomes has been reported in subarachnoid hemorrhage. We evaluated the relationship between early pCO2 changes, ischemic lesions and outcomes in patients with intracerebral hemorrhage (ICH). METHODS: Consecutive patients with spontaneous ICH were enrolled in an observational cohort study conducted between 2006 and 2019. Patient characteristics and discharge outcome were prospectively recorded. Arterial blood gas (ABG) measurements and mechanical ventilation settings in the first 72 h of admission were retrospectively collected. MRI images were adjudicated for diffusion-restricted lesions consistent with ischemia and distant from the hematoma. We examined the associations between pCO2 changes, ischemic lesions, and discharge outcomes by univariate and adjusted analyses. RESULTS: ABG data were available for 220 patients. Hyperventilation occurred in 52 (28%) cases and was not associated with clinical severity. Lower initial pCO2 was associated with greater risk of in-hospital death (OR 0.94 per mmHg, 95%CI [0.89, 0.996], p = 0.042) after adjustment for ICH Score, pneumonia and mechanical ventilation requirements. MRI data were available for 33 patients. Lower pCO2 was associated with a higher risk of ischemic lesions, except in patients with low initial systolic blood pressure (p < 0.05 for main and blood pressure interaction effects), after adjustment for other predictors. CONCLUSIONS: In ICH patients with spontaneous ventilation, lower pCO2 was independently associated with greater risk of in-hospital death. In patients with elevated initial blood pressure, who undergo blood pressure reduction per guideline recommendations, lower pCO2 was associated with increased risk to develop ischemic lesions.

Clinical Distinction of Cerebral Ischemia and Triaging of Patients in the Emergency Department: Mimics, Wake-ups, Late Strokes, and Chameleons.

Non-stroke conditions may present in ways suggestive of ischemic stroke (ie, stroke mimic). Alternatively, the clinical presentation of ischemic stroke can vary considerably and may appear similar to another condition (ie, stroke chameleon). Common and uncommon mimics and chameleons are presented with discussion of key considerations to improve diagnostic accuracy.

A Critical Examination of Subgroup Analyses: The National Acute Spinal Cord Injury Studies and Beyond.

The use of high-dose methylprednisolone for acute spinal cord injury continues to be a topic of debate. This controversy largely stems from fundamental issues in statistical interpretation of trial data, most notably subgroup analyses. The purpose of this review is to discuss important examples of improper subgroup analysis and encourage better practices in future research.

High vascular delivery of EGF, but low receptor binding rate is observed in AsPC-1 tumors as compared to normal pancreas.

PURPOSE: Cellular receptor targeted imaging agents present the potential to target extracellular molecular expression in cancerous lesions; however, the image contrast in vivo does not reflect the magnitude of overexpression expected from in vitro data. Here, the in vivo delivery and binding kinetics of epidermal growth factor receptor (EGFR) was determined for normal pancreas and AsPC-1 orthotopic pancreatic tumors known to overexpress EGFR. PROCEDURES: EGFR in orthotopic xenograft AsPC-1 tumors was targeted with epidermal growth factor (EGF) conjugated with IRDye800CW. The transfer rate constants (k(e), K12, k21, k23, and k32) associated with a three-compartment model describing the vascular delivery, leakage rate and binding of targeted agents were determined experimentally. The plasma excretion rate, k (e), was determined from extracted blood plasma samples. K12, k21, and k32 were determined from ex vivo tissue washing studies at time points ≥ 24 h. The measured in vivo uptake of IRDye800CW-EGF and a non-targeted tracer dye, IRDye700DX-carboxylate, injected simultaneously was used to determined k23. RESULTS: The vascular exchange of IRDye800CW-EGF in the orthotopic tumor (K12 and k21) was higher than in the AsPC-1 tumor as compared to normal pancreas, suggesting that more targeted agent can be taken up in tumor tissue. However, the cellular associated (binding) rate constant (k23) was slightly lower for AsPC-1 pancreatic tumor (4.1 × 10(-4) s(-1)) than the normal pancreas (5.5 × 10(-4) s(-1)), implying that less binding is occurring. CONCLUSIONS: Higher vascular delivery but low cellular association in the AsPC-1 tumor compared to the normal pancreas may be indicative of low receptor density due to low cellular content. This attribute of the AsPC-1 tumor may indicate one contributing cause of the difficulty in treating pancreatic tumors with cellular targeted agents.

In vivo quantification of tumor receptor binding potential with dual-reporter molecular imaging.

PURPOSE: Receptor availability represents a key component of current cancer management. However, no approaches have been adopted to do this clinically, and the current standard of care is invasive tissue biopsy. A dual-reporter methodology capable of quantifying available receptor binding potential of tumors in vivo within a clinically relevant time scale is presented. PROCEDURES: To test the methodology, a fluorescence imaging-based adaptation was validated against ex vivo and in vitro measures of epidermal growth factor receptor (EGFR) binding potential in four tumor lines in mice, each line expected to express a different level of EGFR. RESULTS: A strong correlation was observed between in vivo and ex vivo measures of binding potential for all tumor lines (r = 0.99, p < 0.01, slope = 1.80 ± 0.48, and intercept = -0.58 ± 0.84) and between in vivo and in vitro for the three lines expressing the least amount of EGFR (r = 0.99, p < 0.01, slope = 0.64 ± 0.32, and intercept = 0.47 ± 0.51). CONCLUSIONS: By providing a fast and robust measure of receptor density in tumors, the presented methodology has powerful implications for improving choices in cancer intervention, evaluation, and monitoring, and can be scaled to the clinic with an imaging modality like SPECT.

Imaging targeted-agent binding in vivo with two probes.

An approach to quantitatively image targeted-agent binding rate in vivo is demonstrated with dual-probe injection of both targeted and nontargeted fluorescent dyes. Images of a binding rate constant are created that reveal lower than expected uptake of epidermal growth factor in an orthotopic xenograft pancreas tumor (2.3 x 10(-5) s(-1)), as compared to the normal pancreas (3.4 x 10(-5) s(-1)). This approach allows noninvasive assessment of tumor receptor targeting in vivo to determine the expected contrast, spatial localization, and efficacy in therapeutic agent delivery.