[Quantitative assessment of pressure relief at the sacral area in adults lying supine on the operating room table].

BACKGROUND: It is important to prevent development of the pressure ulcers in patients undergoing lengthy surgery, particularly at areas of skin overlying bony prominences. This study was designed to investigate distribution of the interface pressure (IP) over the body area (from the head to pelvic area) in supine adults and also evaluate the ability of a polyurethane-made cushion to reduce the IP at their sacral area. METHODS: Utilizing a recently developed device to measure the IP (ERGO-CHECK, ABW Co., Germany), we evaluated distribution of the IP (estimated per 3 x 4 cm2 area) over the body area in healthy volunteers (n=31) and patients under general anesthesia (n=6) lying supine on the operating room (OR) table. RESULTS: In all the subjects, the highest IP was generated at the sacrum; 62.5 +/- 23.8 (mean +/- SD) and 35.7 +/- 5.5 mmHg in the volunteers and patients, respectively. The polyurethane-made, "doughnut" cushion (5 cm in thickness) inserted between the pelvic area and the OR table significantly reduced (P < 0.05) the IP at the sacrum in both groups: the IPs after the insertion in the volunteers and patients were 35.1 +/- 11.1 and 25.6 +/- 6.5 mmHg, respectively. In addition, the insertion significantly reduced (P < 0.05) the high-risk area (i.e., area of IP > 32 mmHg) in both groups. CONCLUSIONS: Quantitative assessment of the IP would be useful in evaluating precisely the effectiveness of various types of pillows, cushions, or mattresses designed to reduce the IP.

Contribution of nifedipine-insensitive voltage-dependent Ca2+ channel to diameter regulation in rabbit mesenteric artery.

We investigated a possible role of nifedipine-insensitive high voltage-activated (NI-HVA) Ca2+ channels in arterial diameter regulation in the semi-terminal branches of rabbit mesenteric artery (RMA). From these branches, NI-HVA Ca2+ currents showing almost identical properties to those previously identified in a similar region of guinea-pig [Circulation Research 1999;85:596-605] were recorded with whole-cell patch clamp recording. With video-microscopic measurement, the diameter of RMA segments perfused intraluminally at a constant rate (2-6 mL/h; 269 +/- 9 micro m, n = 27) decreased by 50-60% by raising the external K+ concentration ([K+]o) to 75 mM, a substantial part of which remained after addition of 1-10 micro M nifedipine (44 +/- 5% of initial diameter, n = 27). This nifedipine-insensitive diameter decrease (NI-DD) appeared to consist of initial transient and subsequent tonic phases (this separation was, however, not always clear), was resistant to tetrodotoxin, and was completely abolished in Ca2+-free or 100 micro M Cd2+-containing bath solutions. The magnitude of NI-DD increased depending on [K+]o with a threshold concentration of 20-40 mM. Raising the external Ca2+ concentration dose-dependently increased the magnitude of NI-DD, the extent being more prominent in the late tonic phase. Combined application of caffeine (10 mM) with ryanodine (3 micro M) produced a large transient NI-DD, which strongly attenuated the NI-DD evoked by a subsequent elevation in [K+]o. Using the fura-2 spectrofluorimetric Ca2+ imaging technique, a nifedipine-insensitive [Ca2+]i increase showing similar [K+]o-dependence and Cd2+ sensitivity to NI-DD was observed. These properties of NI-DD accord with those of NI-HVA Ca2+ channels, thus suggesting their contribution to small arterial diameter regulation in RMA.