We localized the sites of vasodilation of inhaled nitric oxide (NO), a selective pulmonary vasodilator, and sodium nitroprusside (SNP) in isolated rat lungs. The sites were determined by analyzing the arterial, venous, and double-occlusion data with a two-resistor (small arteries and veins) three-capacitor (large arteries, large veins, and capillaries) model of the pulmonary vascular bed. Inhaled NO (170 and 670 ppm) and SNP (22.5 and 45.0 micrograms) decreased the small-artery resistance by 7.4 +/- 1.6, 17.2 +/- 2.2, 14.2 +/- 2.8, and 21.4 +/- 3.4% and the small-vein resistance by 13.5 +/- 3.2, 20.3 +/- 3.4 (SNP of 22.5 micrograms not significant), and 9.3 +/- 3.3%, respectively, in blood-perfused lungs (n = 12). Similar results were observed in Krebs-perfused lungs (n = 12). Capillary compliance was unaffected by inhaled NO and SNP. SNP increased the large-artery capacitance by 40.0 +/- 8.6 and 69.3 +/- 9.7%, whereas inhaled NO had no effect. SNP increased the large-vein capacitance by 31.0 +/- 8.7 and 48.0 +/- 10.7%, whereas inhaled NO had no effect in blood-perfused lungs. However, in Krebs-perfused lungs inhaled NO and SNP (45.0 micrograms only) increased the large-vein capacitance by 43.3 +/- 11.9, 41.4 +/- 14.2, and 44.2 +/- 11.0%. In conclusion, in blood-perfused isolated rat lungs inhaled NO and SNP dilate small-resistance arteries and veins, whereas SNP but not inhaled NO dilates larger capacitance arteries and veins. Furthermore, blood appears to prevent the downstream vasodilation by inhaled NO on larger capacitance pulmonary veins.

Administration, Inhalation↗

PubMed1994

Comparison of the force required for dural puncture with different spinal needles and subsequent leakage of cerebrospinal fluid.

An in vitro model was used to determine the force required to pierce bovine dura with a range of new spinal needles and to measure the subsequent leakage rate of cerebrospinal fluid (CSF). A significantly greater force was required to pierce the dura with pencil-point style needles compared to Quincke needles of the same size. Quincke needles caused a greater loss of CSF than their pencil-point equivalents. The results suggest that there is not likely to be a significant reduction in postdural puncture headache (PDPH) using a 27-gauge pencil-point needle compared to a 25-gauge needle that may be easier to use. Different makes of the same design and gauge of needle showed significant differences in the amount of CSF leakage, which may influence the clinician's choice of needle.

Anesthesia, Epidural↗

PubMed1994

Yet another source of needlestick injury: a case of needle packaging not up to scratch?

Explore the source record for details and available documents.

Drug Packaging↗