The effect of local controlled cooling on the digital systolic blood pressure in the hand was studied in 25 In an effort to make objective measurements in patients with primary or secondary Raynaud's syndrome, several workers have studied blood flow in the hand ( I , 2) before and after local cooling, blood viscosity ( 3 ) changes at low temperatures and photoelectric measurement of pulse amplitude (4) during stepwise cooling. Nielsen ( 5 ) suggested that photoplethysmography was unsuitable for detecting pulsation when finger systolic pressure was less than 30-40mmHg. He described a method (5,6) of indirectly measuring finger systolic pressure at different temperatures using a proximal occluding cuff and a proximal cooling cuff, and strain gauge plethysmography to detect distal pulsation. However, although Nielsen achieved objective pressure measurements that separated normals from patients with primary Raynaud's disease (5,7), he found it necessary to use body cooling with a cooling blanket at an ambient room temperature of 22°C to achieve this separation. We have adopted his method of local finger cooling, using photoplethysmography instead of strain gauge plethysmography to detect distal pulsation. and a lower ambient room temperature of 17.5-18 "C instead of total body cooling. The aim of our study was to measure and attempt to identify any difference in the response to cooling in controls and patients with Raynaud's syndrome. Patients and methodsTwenty-five normal volunteers (21 women, 4 men: age 20-40 years) acting as controls and 25 patients (20 women, 5 men: age 22-67 years) with Raynaud's syndrome were studied. Seven patients had systemic sclerosis. 2 had Buerger's disease and in 14 the diagnosis was unknown. In each subject the brachial systolic blood pressure and the systolic blood pressure of the cooled middle finger and of the noncooled (reference) index finger were measured. This was achieved using a thermostatically controlled culT, which could be pressurized and simultaneously perfused with water at 30°C or 10°C. on the middle digit. a non-cooled cuff pressurized by air at ambient room temperature on the index finger and photoplethysmographic (PPG) probes to detect the distal pulse on the tip of each finger. A commercially available digit cooling machine (Medimatic, Copenhagen, Denmark) was used. Both cuffs were capable of being pressurized and deflated simultaneously; cuff pressure was monitored via an Akers transducer (AE 840) and amplifier and recorded on a pen recorder (Watanabe MC611). The PPG probes (Medasonics PH77). placed on the pulp of each digit, were connected via a Photo Pulse Adaptor (Medasonics PA13) and the tracings were recorded on the same pen recorder. Thus, there were simultaneous recordings of cuff pressure and distal pulses.The pre-test conditions for all subjects involved no tobacco or alcohol (in the preceding 2 hours) and a light meal only, and for the test all were rested for 20 minutes in light clothing at a room temperature maintained at 17.5-18 "C. Cuffs on both fing...

Background This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. Methods This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score‐matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score‐matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery. Results A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score‐matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498). Conclusion There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast‐induced nephropathy should not be used as a reason to avoid contrast‐enhanced CT.

The peri-operative use of angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers is thought to be associated with an increased risk of postoperative acute kidney injury. To reduce this risk, these agents are commonly withheld during the peri-operative period. This study aimed to investigate if withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers peri-operatively reduces the risk of acute kidney injury following major non-cardiac surgery. Patients undergoing elective major surgery on the gastrointestinal tract and/or the liver were eligible for inclusion in this prospective study. The primary outcome was the development of acute kidney injury within seven days of operation. Adjusted multi-level models were used to account for centre-level effects and propensity score matching was used to reduce the effects of selection bias between treatment groups. A total of 949 patients were included from 160 centres across the UK and Republic of Ireland. From this population, 573 (60.4%) patients had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers withheld during the peri-operative period. One hundred and seventy-five (18.4%) patients developed acute kidney injury; there was no difference in the incidence of acute kidney injury between patients who had their angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers continued or withheld (107 (18.7%) vs. 68 (18.1%), respectively; p = 0.914). Following propensity matching, withholding angiotensin-converting enzyme inhibitors or angiotensin-2 receptor blockers did not demonstrate a protective effect against the development of postoperative acute kidney injury (OR (95%CI) 0.89 (0.58-1.34); p = 0.567).

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A rational perfect cuboid is a rectangular parallelepiped whose edges and face diagonals are given by rational numbers and whose space diagonal is equal to unity. Recently it was shown that the Diophantine equations describing such a cuboid lead to a couple of parametric families of elliptic curves. Two and three descent methods for calculating their ranks are discussed in the present paper. The elliptic curves in each parametric family are subdivided into two subsets admitting 2-descent and 3-descent methods respectively.