Relative risks of ventriculostomy infection and morbidity

Summary Ventricular catheter placement is a common procedure for the management of increased intracranial pressure. Hypotheses regarding the etiology of infection of catheters center on two alternative assumptions: 1) contamination leading to infection occurs at the time of catheter insertion, implying that catheter duration has minimal effect on infection risk; and 2) infection of catheters derives from catheter contamination after insertion, suggesting that duration of catheter use may significantly affect infection risk.We have studied the relative complication rate of ventricular catheter insertions using a retrospective approach (n=161 patients and 253 catheter insertion procedures). The overall infection rate was 4.1%, but the daily infection hazard increased exponentially with time, to a maximum daily rate of 10.3% by day 6 of catheter insertion. This increasing risk appears most consistent with the second hypothesis. The risk of non-infectious complications was 5.6%, including hemorrhagic occurrences and misplacement severe enough to require a new catheter insertion. The daily hazard of infection approximately equalled the non-infectious risk of routine catheter replacement by day 5.Additional prospective data on the daily risk of CSF infection and the appropriateness of antibiotic prophylaxis either at the time of ventricular catheter insertion or continued through the catheter's-presence may be required to both definitively identify which hypothesis of infection risk is correct and whether antibiotics can significantly ameliorate this risk.     

Effects of radiation on fixation of non-cemented porous-coated implants in a canine model

A non-weight-bearing porous-coated rod was implanted bilaterally in the proximal part of the humerus in thirty-five adult male mongrel dogs. In all of the animals, one limb was treated with radiation and the opposite limb served as the control. In twenty-one animals, the dose was 1000 centigrays (rads) and in fourteen, it was 500 centigrays. The strength of fixation and the volume fraction of ingrowth of bone were determined two, four, and eight weeks after the operation in the group that received 1000 centigrays and two and four weeks after the operation in the group that received 500 centigrays. Treatment with 500 centigrays had no significant effect on the strength of fixation or the amount of ingrowth of bone. In contrast, at two weeks, treatment with 1000 centigrays had reduced the strength of fixation to 50 per cent of the control value (p less than 0.01), although, at four and eight weeks, the strength of fixation was not significantly different than that in the control limb. The amount of ingrowth of bone in the irradiated limb was significantly reduced at two weeks (30 per cent of the control value) (p less than 0.01), four weeks (70 per cent of the control value) (p less than 0.05), and eight weeks (56 per cent of the control value) (p less than 0.05).     

Do weighted nasoenteric feeding tubes facilitate duodenal intubations?

A widely held assumption is that postpyloric intubations occur more often with weighted than with unweighted nasally inserted feeding tubes. This randomized, prospective study compared the frequency of duodenal intubations using weighted and unweighted nasoenteric feeding tubes. One hundred sixteen patients had either weighted (61 patients) or unweighted (55 patients) 10F silicone elastomer feeding tubes inserted nasally 85 cm. Tubes were placed with wire stylets. Tube positions were verified radiographically within 4 hr after insertions. Radiographs were repeated daily for 3 days or until duodenal intubation occurred. Successful duodenal intubations were achieved in 35 patients (57%) with weighted feeding tubes and in 37 patients (67%) with unweighted feeding tubes. This difference was not significant. Weighted nasoenteric feeding tubes offer no advantage over unweighted tubes in achieving duodenal intubations.     

Repair of Achilles tendon ruptures with a polylactic acid implant: assessment with MR imaging

An investigational tendon repair device composed of a polymer of lactic acid (PLA) is currently undergoing multicenter clinical trials for use in repairing rupture of the Achilles tendon. The advantages of the PLA device include high tensile strength and the induction of a rapid proliferative tissue response resulting in a shorter rehabilitation period than with conventional surgical repair. We reviewed 16 MR examinations performed in 10 patients 3-35 months after repair to characterize the MR appearance. All 16 T1-weighted sagittal images revealed a thickened fusiform tendon with streaks of moderate signal within the tendon corresponding to the PLA device and its surrounding collagenogenic response. The double-echo T2-weighted axial images at the mid tendon level demonstrated progressive changes in the signal pattern of the central portion of the tendon that reflected the maturation of the healing tendon. All tendons repaired with PLA implants were uniformly hypertrophied relative to the contralateral normal side because of the induced proliferative collagenogenic ingrowth. Two follow-up MR examinations were performed in six patients and showed mean reductions in tendon caliber of 24% and 30% at the mid and inferior levels. MR imaging of the Achilles tendon repaired with PLA implants shows a diffusely thickened tendon with streaks of signal within the tendon that distinguish it from tendons repaired by conventional techniques.     

Real-time movie imaging from a single cardiac cycle by NMR

Using a 1-m-bore superconductive magnet at 0.1 T, whole-body transverse images through adult humans have been obtained at repetition times of 57 ms. The techniques used were minor variations of echo-planar imaging (EPI) employing large pulsed gradients to provide complete coverage of the plane in phase space, and low-angle RF excitation sequences allowing rapid repetition of the experiment. In addition active magnetic screening of the gradient coils was implemented to protect the surrounding magnet from the eddy currents induced by the necessarily fast switching of the large gradient fields.     

Splenocyte response to T cell-derived cytokines in thymectomized Xenopus.

A miniaturized, “hanging-drop” bioassay reveals that splenocytes from earlythymectomized (Tx) Xenopus can respond (by enhanced thymidine incorporation) to thymicdependent “cytokines” generated in PHA- or alloantigen-stimulated cultures. Preliminary evidence, using fluorescence activated cell sorting, indicates that surface IgM⁻ splenocytes, rather than sIgM⁺ cells, from Tx toads are sensitive to the crude, splenocyte-derived, active supernatants. Although these responsive cells display residual, but low, reactivity to PHA, their thymus independence is suggested by flow cytometric observations using the anti-T cell monoclonal antibody XT-1. The development of “T-like” cells in Tx Xenopus is discussed.     

The assessment of pain in rheumatoid arthritis: disease differentiation and temporal stability of a behavioral observation method

An observation method for the assessment of pain behaviors in patients with rheumatoid arthritis (RA) has been developed. We investigated the extent to which the frequencies of pain behaviors differentiated patients with RA and patients with chronic low back pain from depressed and nondepressed, pain free, control subjects. The reliability of the pain behavior frequencies of patients with RA across 2 observation sessions also was determined. Total pain behavior scores clearly differentiated patients with RA and low back pain from depressed and nondepressed, pain free, control subjects. Pain behavior observed in patients with RA showed a high degree of stability over time. The results of our study suggest that the behavioral observation method will prove useful in the assessment of RA pain in clinical and research settings.     

Avidin-ferritin cytochemistry on lectin receptors of uterine epithelial cells in the rat

Cytochemistry using biotinylated lectins and an avidin-ferritin label has been combined with freeze-fracture to study the relationship between surface carbohydrates and intramembranous particles in uterine epithelial cells. We find no structural relationship between the 2 classes of membrane components and consider the significance of this finding.     

Use of end-tidalPco 2 and transcutaneousPco 2 as noninvasive measurement of arterialPco 2 in extubated patients recovering from general anesthesia

This study was designed to assess the accuracy of end-tidalPco ₂ and transcutaneousPco ₂ as measurements of arterialPco ₂ in extubated, spontaneously breathing patients recovering from general anesthesia. In 30 patients, measurement of arterial transcutaneous, and end-tidalPco ₂ were taken simultaneously with body temperature approximately every 15 minutes over a 2-hour period. ArterialPco ₂ values were corrected for body temperature. Values for Paco ₂ were compared with those forPetCO₂ and Psco ₂ by linear regression analysis and by calculation of bias ± precision. Thirty-six percent of the capnogram tracings obtained did not develop a plateau phase. We found poor correlation between end-tidal and arterialPco ₂ regardless of the shape of the capnogram tracing, as well as poor correlation between transcutaneous and arterialPco ₂. Although the measurements of bias and precision of noninvasivePco ₂ monitors in this population are comparable to studies in other populations, we advise caution in relying on the routine use ofPetCO₂ or Psco ₂ for the noninvasive assessment of respiratory depression in extubated, spontaneously breathing patients recovering from general anesthesia.