A photoplethysmographic technique for detecting vascular compromise: a preliminary report

We have developed a photoplethysmographic technique for monitoring early signs of vascular compromise in extremities affected by direct vessel trauma, crushing trauma, or circumferential burns. The technique consists of positioning a small infrared emitter-detector array shielded from room light over a nailbed of the affected extremity and connecting the array to standard electronic monitoring equipment, thus producing a pulse tracing very similar in contour to an arterial pressure wave. In normal volunteers, simultaneous observations of the tracing and studies of muscle blood flow using Xe133 clearance showed correspondence of disappearance of the plethysmographic signal with limb-threatening levels of ischemia produced by inflation of a blood-pressure cuff. Studies comparing this technique to compartment pressures and arterial flow determined by ultrasound Doppler measurement are continuing. Clinically, we have used this monitoring technique on 29 trauma patients thus far, including 18 with circumferential full-thickness burns of at least one extremity. We believe that these preliminary studies suggest that photoplethysmography is a valuable continuous monitor of vascular status following trauma and a reliable indicator of nutritional blood flow.

Renal hyperconcentration of 99mTc-HEDP in experimental acute tubular necrosis

The effect of transient renal ischemia on renal concentration and distribution of 99mTc-HEDP, 99mTc-DMSA, and 99mTc-DTPA was compared in rabbits with acute tubular necrosis. Scintigrams were obtained after injection in normal rabbits or ones with unilateral or bilateral ischemia. 99mTc-HEDP concentration in ischemic tissue was 8 to 18 times normal 1--4 hours after injection, and the resulting images delineated the morphological changes in the ischemic kidneys more accurately than those obtained with DMSA or DTPA. Calcium concentration in the ischemic kidneys increased sixfold. 99mTc-HEDP may be useful in evaluation of renal failure secondary to tubular injury.

Skeletal and reticuloendothelial imaging in osteopetrosis: case report

Skeletal and reticuloendothelial images, using Tc-99m HEDP and Tc-99m sulfur colloid respectively, were obtained from two adult patients with osteopetrosis. Skeletal images demonstrated increased activity in multiple fracture sites, in mandibular osteomyelitis, in ends of splayed long bones adjacent to joints, and in the epiphyseal ends of short tubular bones. The remainder of the skeleton involved with osteopetrosis showed no generalized increased uptake of Tc-99m HEDP. These findings indicate that metabolic activity in this disease is abnormally increased in the usual areas of bone growth but appears normal elsewhere. Reticuloendothelial imaging showed an almost total lack of activity in the axial and peripheral skeletal marrow space. Anemia, however, was only moderate in these patients. Skeletal scintigraphy may be useful to evaluate the presence and extent of the frequent complications of osteopetrosis, namely fractures and osteomyelitis.

A quantitative evaluation of rheumatoid arthritic activity with Tc-99m HEDP

In an attempt to develop a quantitative method of evaluating rheumatoid arthritic activity, Tc-99m HEDP joint uptake values and joint-to-bone ratios were studied in ten adult rheumatoid arthritic patients and 17 nonarthritic patients. A joint-to-bone activity ratio of 1.8 at the fourth hour after injection (RA Index) discriminated clinically active rheumatoid arthritic joints from control joints with 95% accuracy. Serial studies on five patients during drug trial demonstrated a positive correlation between RA Index and the clinical manifestations of rheumatoid arthritic activity. The RA Index may be a useful quantitative parameter for evaluation of rheumatoid arthritic activity following therapy.

Hepatic emboli following inferior vena caval ligation. Brief report

Radionuclide venography performed by foot vein injection of 99mTc MAA and 99mTc DTPA in a 34-year-old man approximately one year after inferior vena caval ligation demonstrated an unusual collateral pathway between the veins of the lower extremities and the portal vein, and also evidence for multiple hepatic emboli. This is a newly recognized sequela of inferior vena caval ligation.

Localized cryptococcal osteomyelitis

Cryptococcal infection of the skeletal system alone is rare. The authors report a case of osteomyelitis caused by Cryptococcus neoformans involving the distal humerus and skull, with roentgenographic and scintigraphic findings and pathological confirmation.