Proteinuria in fighter pilots after high +Gz exposure

Exposure to high gravitational forces acting along the body axis towards the feet (+Gz) causes considerable strain on several organ systems, including the kidneys. During +Gz tolerance studies without anti-G suits, significant amounts of protein and hyaline casts were found in 17 of 20 fighter pilots after centrifugation. The G load alternated between 3.5 and 5.5 G. Mean time in the centrifuge was 15 min. For comparison we examined another group of 19 fighter pilots after air combat maneuver training with anti-G suits. None showed proteinuria. The proteinuria most likely indicates a severely depressed renal blood flow during centrifugation.     

Universal solvent/detergent-treated fresh frozen plasma (Uniplas--rationale and clinical properties

Transfusions with incompatible blood products including plasma are a well-known problem. The present study was performed to test the effects of Uniplas, universal plasma that can be transfused regardless of a patient's blood group, with respect to bleeding and hemostatic activity. The study comprised 84 adult patients scheduled for elective openheart surgery. A total of 55 patients received plasma transfusions, while 29 patients not requiring plasma served as controls. If plasma transfusion was indicated during operation or over the two following days, patients were randomised 2:1 to receive Uniplas or Octaplas of blood group AB. Relevant clinical observations were recorded and blood tests taken repeatedly. The transfused patient groups were comparable, and no significant differences were observed with respect to activated clotting time (ACT), activated partial thromboplastin time (APTT) or postoperative bleeding into chest drains. The median number of transfused units of Uniplas was 3, with a range of 1-23, while the median for Octaplas was 2 with a range of 1-11. These differences were not significant.Thus, Uniplas has a similar effect as Octaplas in the treatment of bleeding in patients undergoing openheart surgery. Uniplas can therefore substitute for Octaplas and eliminate the risk of ABO-incompatible transfusions.     

Universal fresh frozen plasma (Uniplas): a safe product in open-heart surgery

Objective To test the tolerability and safety of the universal plasma Uniplas [solvent/detergent (SD)-treated plasma], infused regardless of the patient's blood group.Design Prospective, parallel group, controlled and observer-blinded study, randomized with respect to patients requiring plasma transfusion.Setting Cardiothoracic operating room and ICU in a university hospital.Patients Eighty-four patients undergoing open-heart surgery comparing three parallel treatment groups and one control group.Interventions The Uniplas treatment group was subdivided into patients with blood group A, B or AB, and group O. The treatment group receiving Octaplas of type AB, was not subdivided. Patients who did not require any plasma transfusion served as control.Measurements Complement activation (C3bc, TCC), direct antiglobulin test (DAT) and other immunohaematological tests, tests for haemolysis, and relevant clinical observations during treatment phase. Blood samples were collected again after 6 months for evaluation of viral safety.Results Of the 84 patients, 29 served as control group. Uniplas was transfused in 36 of the patients (1–23 units). Octaplas was transfused in 19 patients (1–11 units). During the study no clinical adverse events related to plasma transfusion were observed. The degree of complement activation C3bc and TCC, a recommended test for biocompatibility, did not show any increased activation after Uniplas or Octaplas transfusion. No haemolytic reactions, positive DAT-tests or viral transmissions were observed after Uniplas transfusion.Conclusion In open-heart surgery, Uniplas, which can be transfused regardless of a patient's blood group, was well-tolerated and gave no adverse drug reactions.     

Interstitial fluid pressure in human skin measured by micropuncture and wick-in-needle

Interstitial fluid pressure (Pi) has been measured in human skin by micropipettes (tip diam. 2-4 micron) and compared to pressures obtained by wick-in-needle technique. The micropipettes were connected to a servocontrolled counterpressure system (Wiederhielm) and were introduced into the skin distally at the dorsum of the fifth finger after immobilization of the upper extremity. The wick-in-needle was introduced at the dorsum of the hand. With the finger at heart level and at a room temperature of 24 +/- 1 degree C, the mean Pi measured by micropuncture was -3.1 mmHg (range -5 to -0.5 mmHg), while the corresponding mean Pi measured with wick-in-needle was 0.0 mmHg (range -1.7 to +3 mmHg). During venous stasis Pi increased as measured by both methods, but the increase recorded by micropuncture was largest. It is concluded that the wick-in-needle probably overestimates Pi in the normally hydrated human skin of the hand due to inflammation at the implantation site, and that the overestimation diminishes as tissue hydration increases.     

Cold and warm infusion of Ringer's acetate in healthy volunteers: the effects on haemodynamic parameters,transcapillary fluid balance,diuresis and atrial peptides

The effects of Ringer's acetate (RAc) infusion with different temperatures, 18d?C compared to 36d?C, were studied in 20 healthy volunteers. An infusion volume of 20% of the estimated extracellular volume was given over 45 min. Before and after the RAc infusion, interstitial colloid osmotic pressure and interstitial fluid hydrostatic pressure were measured on the lateral part of the thorax and in the lower leg. Blood sampling and pressure measurements were performed through a cannula placed in the left radial artery, and arterial oxygen saturation was measured by pulse oximetry. Atrial peptides ANF (99–126) and ANF (1–98) in plasma were measured as indicators of volume loading. Cold RAc infusion increased mean arterial pressure from 82 (s.d. ± 7) to 96 (s.d. ± 9) mmHg (10.9–12.8 kPa) at the end of the infusion with a simultaneous fall in heart rate. Warm RAc infusion gave no changes in blood pressure or heart rate. The arterial oxygen saturation during the infusion of cold RAc was higher than during warm RAc infusion. Cold infusion produced the expected haemodilution with a fall in erythrocyte volume fraction (EVF) from 0.39 (± 0.03) to 0.33 (± 0.03) and a fall in plasma colloid osmotic pressure (COP_p) from 21.7 (± 1.1) mmHg to 15.0 (± 1.3) mmHg (2.9–2.0 kPa). Warm infusion induced a nearly identical haemodilution. Interstitial colloid osmotic pressure fell from 11.6 (± 2.3) mmHg to 8.9 (± 2.7) mmHg (1.5–1.2 kPa) after warm infusion while cold infusion gave no changes. The changes in interstitial fluid hydrostatic pressure were not significant. Cold infusion induced a higher diuresis compared to warm RAc infusion. ANF increased during cold, but not during warm infusion. We conclude that infusions of RAc at 18d?C vs. 36d?C have different volume effects. Cold infusion increased blood pressure and diuresis, while warm infusion induced peripheral vasodilation with increased capillary leakage and subcutaneous oedema formation.     

Transcapillary fluid balance in pre-eclampsia

The fluid transport between the plasma and interstitial fluid compartment is governed by the Starling forces, i.e. the capillary pressure (Pc), interstitial fluid hydrostatic pressure (Pi) and colloid osmotic pressure in plasma (COPp) and interstitial fluid (COPi). Interstitial fluid was collected from subcutaneous tissue on the thorax and ankle by implanted wicks and Pi was measured using the 'wick-in-needle' technique. In pre-eclampsia, COPp is reduced due to hypoproteinaemia and this predisposes towards loss of fluid from the vascular compartment. An important oedema-preventing mechanism is reduction of COPi, which serves as a homeostatic buffer against increased capillary filtration. This mechanism works in moderate, but not in severe pre-eclampsia. A higher COPi was found both at the thorax (8.3 vs 7.0 mmHg) and ankle (5.9 vs 3.9 mmHg) in the group with severe pre-eclampsia compared with the group moderate pre-eclampsia, in spite of a significant reduction in COPp (15.5 vs 19.9 mmHg). These findings suggest that an increased microvascular permeability of plasma proteins to subcutaneous tissue contributes to COPp reduction in severe pre-eclampsia.     

Transcapillary fluid dynamics during the menstrual cycle

Transcapillary fluid dynamics in the follicular and luteal phase in women without symptoms of premenstrual syndrome were studied. Interstitial colloid osmotic pressure was measured by the "wick" method and interstitial hydrostatic pressure by the "wick-in-needle" method in subcutaneous tissue on the thorax and ankle. From follicular to luteal phase, the following changes were observed: Colloid osmotic pressures were significantly reduced, both in plasma (mean 2.5 mm Hg) and in the interstitium (thorax mean 1.9 mm Hg and ankle mean 2.0 mm Hg). The interstitial hydrostatic pressures did not change. There were no significant changes in serum albumin, hemoglobin, or hematocrit. A slight, but significant, weight gain was observed (mean 0.7 kg). The reduced plasma and interstitial colloid osmotic pressures in the luteal phase may be due to water retention, but the observed reductions in colloid osmotic pressures are probably not fully explained by simple dilution. A reduction in total protein mass in the luteal phase is suggested.     

A telemetric technique for studies of venous pressure in the human leg during different positions and activities

Summary. The pressure in the saphenous vein of the lower leg was monitored by ordinary ECG telemetry equipment supplied with a pressure transducer, a chopper and an extra filter. In eight healthy volunteers venous pressure averaged 802 5 (SD) mmHg in the standing position and 21210 (SD) mmHg during slow walking. When the subjects were occupied with laboratory work in upright position the mean venous pressure was 40–50 mmHg, similar to that obtained sitting at a desk: 48 ± 5 (SD) mmHg.     

Interstitial colloid osmotic and hydrostatic pressures in subcutaneous tissue of human thorax

Interstitial colloid osmotic pressure (π_i) of human subcutaneous tissue was measured simultaneously by three different techniques: in fluid collected by implanted nylon wicks or empty wick catheters, and by implantable colloid osmometers. Hydrostatic pressure in interstitial fluid (P_i) was measured by wick catheters and by wick-in-needle technique. The implantations were done at heart level on the side of the thorax in 15 healthy male subjects. They were divided in two groups, one for a direct comparison of the methods and one for a further investigation on the effect of suction in empty wick catheters. In nylon wicks implanted for 60 min, π_i averaged about 16 mm Hg in both groups. In fluid sampled with empty wick catheters, a suction pressure of ?10 cm H₂O, and 60-min implantation time, the mean π_i was 10.5 and 12.9 mm Hg in the first and second group, respectively. Two factors contributed to lowering of π_i in empty wick catheters: dilution of the samples by saline contained in the wick catheter before implantation, and a π_i-lowering effect of suction. Measurements with implantable colloid osmometers averaged 9.8 mm Hg. Mean implantation time was 30 min. However, the π_i value was positively correlated to implantation time and linear extrapolation to 60 min gives π_i values similar to implanted nylon wicks. We therefore conclude that the three methods give the same π_i in the same area of human subcutaneous tissue provided equal implantation time and little or no suction in empty wick catheters. P_i was ?0.2 mm Hg with both wick catheter and wick-in-needle technique.     

Plasma concentrations of atrial peptides ANF(l-98) and ANF(99–126) after intravenous infusion: effect of infusate temperature

Summary. Atrial peptides ANF(l-98) and ANF(99–126) were measured in plasma before and after infusion of Ringer-Acetate solution in healthy volunteers. The solution was infused over a 45 min period in an amount equal to 20 per cent of estimated extra-cellular volume. We found that the increase in atrial peptide immuno-reactivity after infusion depended on the temperature of the infusate. The molar increase in ANF(l-98) was much larger than the increase in ANF(99–126). We speculate that plasma levels of ANF(l-98) may be a clinically useful parameter of atrial distension secondary to hypervolaemia.