The dynamics of vascular volume and fluid shifts of lactated Ringer's solution and hypertonic-saline-dextran solutions infused in normovolemic sheep.

UNLABELLED: Infusions of hyperosmotic-hyperoncotic solutions such as hypertonic saline dextran (HSD) are used in Europe for resuscitation of traumatic shock and perioperative volume support as an adjunct to conventional isotonic crystalloids. Whereas plasma volume expansion of HSD has been measured at single time points after the intravascular volume expansion, the detailed time course of fluid shifts during and after infusions have not been reported. We compared the time course of volume expansion during and after 30-min infusions of 4 mL/kg HSD and 25 mL/kg lactated Ringer's solution (LR) in normovolemic conscious splenectomized sheep. Peak plasma volume (Evans blue and hemoglobin dilution) expansion was similar for HSD (7.8 +/- 0.9 mL/kg) and the larger sixfold volume of LR (7.2 +/- 0.5 mL/kg). However, 30 min after the 30-min infusion (T60), plasma expansion remained larger after HSD (5.1 +/- 0.9 mL/kg) than after LR (1.7 +/- 0.6 mL/kg). Both solutions caused an equivalent diuresis. Intravascular volume expansion efficiency (VEE), defined as milliliter plasma expansion/milliliter fluid infused at 0 (T30), 30 (T60), and 60 (T90) min after infusion ended was 1.8, 1.3, and 0.8, respectively for HSD, whereas LR provided a VEE of only 0.27, 0.07, and 0.07. The relative expansion efficiency of HSD versus LR, calculated as the ratio (VEE(HSD)/VEE(LR)), was 7-fold that of LR at the end of infusion T30, and 20-fold at T60, but decreased to 9-fold by T120. Intravascular volume dynamic studies of different volume expanders in animals and patients may provide anesthesiologists with a new tool for monitoring the effectiveness of fluid therapy. IMPLICATIONS: Hypertonic saline dextran (HSD) is a new plasma expander recently approved for clinical use in Europe. We compared the plasma volume expansion of HSD versus lactated Ringers (LR) in normovolemic sheep. After a 30 min infusion, HSD was 7 times as effective at expanding volume as an equal volume of LR, but for the next 90 minutes the relative effectiveness of HSD increased to 10-20 times.

Hypertonic saline and dextran in normovolaemic and hypovolaemic healthy volunteers increases interstitial and intravascular fluid volumes.

BACKGROUND: Hypertonic saline (HS) is increasingly used for fluid resuscitation in hypovolaemic patients. Although the effects of HS have been investigated in animal models, controlled studies in healthy human individuals are few. AIM: The effects of i.v. hypertonic saline 75 mg.ml-1 in dextran 70, 60 mg.ml-1 (HSD) infusion on fluid shifts between the interstitial and intravascular fluid spaces, diuresis and haemodynamics were studied in normovolaemic and moderately hypovolaemic healthy volunteers. MATERIAL AND METHODS: Nine fasting subjects received 4 ml.kg-1 HSD as a 10-min infusion in a normovolaemic situation. Seven days later they served as their own controls in a hypovolaemic situation after 10% of the calculated blood volume had been withdrawn during a 15-min period. Before and after the HSD infusion, interstitial colloid osmotic pressure (COPi) and interstitial fluid hydrostatic pressure (Pi) were measured on the lateral part of the thorax. During the study, blood sampling and pressure measurements were performed through a radial artery cannula, and central venous pressure measured through a catheter in the cubital vein. RESULTS: In these awake and normovolaemic healthy volunteers, HSD infusion caused a transitory unpleasant sensation of headache and heat in the thorax up to the throat. A transitory haemodynamic effect was found with increased heart rate (HR), increased mean arterial pressure (MAP) from 77 +/- 5 mmHg to 92 +/- 13 mmHg (P < 0.05) and CVP increase from 5 +/- 1 mmHg to 8 +/- 1 mmHg (P < 0.05) after end of infusion. A haemodilution with increase in calculated blood volume lasting longer than the MAP increase was observed, with decreased COPi from 14.4 +/- 2.2 mmHg to 12.1 +/- 2.0 mmHg (P < 0.05). The diuresis measured at 180 min was higher in the normovolaemic than in the hypovolaemic situation. More pronounced effects of the infused fluid (HSD) on calculated blood volume, interstitial compartment and CVP were observed during moderate hypovolaemia. CONCLUSIONS: HSD infusion resulted in increased calculated blood volume with increased HR, MAP, and CVP. These effects were greater in a hypovolaemic situation. The haemodilution was most likely caused by fluid shifts from the intracellular compartment to the interstitial and vascular fluid spaces, eventually increasing diuresis.

Hypertonic saline and dextran after coronary artery surgery mobilises fluid excess and improves cardiorespiratory functions.

BACKGROUND: Extracorporeal circulation induces increased capillary permeability with fluid leakage into the interstitial space, resulting in positive fluid balance and intravascular hypovolaemia. Hypertonic saline 75 mg.ml-1 in dextran 70, 60 mg.ml-1 (HSD) seems to be of benefit in patients with impaired perfusion. The purpose of the study was to investigate the effects of HSD infusion on fluid balance and cardiorespiratory functions just after the end of cardiac surgery. MATERIAL AND METHODS: Twenty patients with 3-vessel coronary artery disease undergoing elective coronary artery bypass surgery were studied. A standard regimen for anaesthesia, extracorporeal circulation and monitoring was used. The patients were allocated to receive just after the end of surgery either HSD or isotonic saline (4 ml.kg-1 during 30 min) at random in a double-blind single infusion. Ringer's acetate solution was added as needed to stabilise haemodynamics postoperatively. RESULTS: HSD caused mobilisation of the retained intraoperative fluid excess, and increased diuresis. Despite reduced need for extra fluid and a decreased cumulative fluid balance, after HSD infusion patients had increased filling pressures of the heart and improved cardiac output. HSD infusion also induced reduced intrapulmonary venous admixture and improved PaO2 in the early postoperative period. CONCLUSIONS: The present study documents that infused hypertonic saline with dextran just after the end of cardiac surgery resulted in mobilisation of the intraoperative fluid excess with increased urine output in the early postoperative period and improved gas exchange. Despite reduced need for extra i.v. fluid and decreased cumulative fluid balance, after HSD infusion the patients had increased filling pressures of the heart with improved cardiac output.

Leucocyte filtration during cardiopulmonary bypass hardly changed leucocyte counts and did not influence myeloperoxidase, complement, cytokines or platelets.

In some patients, coronary artery bypass surgery induces postoperative organ dysfunction despite an apparently adequate revascularization and good haemodynamic performance. This complication may be caused by activation of the body's inflammatory systems on blood contact with large foreign surfaces in the extracorporeal circuit. Activated leucocytes may play an important role in organ damage, and it is conceivable that leucocyte removal by filtration may decrease the potential side-effects of cardiopulmonary bypass (CPB). The aim of the present study was to investigate possible effects of leucocyte filtration during the whole CPB period in elective coronary artery bypass surgery on biochemical and clinical parameters. Forty patients were randomized to extracorporeal circulation using a leucocyte-depleting filter (group L, n = 20) or to extracorporeal circulation with no leucocyte filter (group C, n = 20). In the leucocyte-depleted group, the mean total white blood cell counts increased from 6.3 (95% confidence interval, 5.5-7.0) x 10(9)/l to 7.0 (5.7-8.3) x 10(9)/l during extracorporeal circulation and in the control group from 6.3 (5.2-7.3) x 10(9)/l to 8.5 (7.2-9.8) x 10(9)/l. The intergroup difference was not statistically significant (p = 0.84). A substantial increase in concentrations of interleukin-6, myeloperoxidase and complement activation products were observed in both groups without statistically significant intergroup differences. It is concluded that the leucocyte-depletion filter did not cause a significant reduction of circulating white blood cells during CPB, and there were no significant differences between the groups with respect to the inflammatory markers studied.

Effect of bolus injection versus continuous infusion of furosemide on diuresis and neurohormonal activation in patients with severe congestive heart failure.

Previous studies have demonstrated that continuous infusion of furosemide results in increased diuresis and natriuresis compared with bolus administration of the drug in patients with severe heart failure. We reasoned that continuous infusion of furosemide caused less activation of neurohumoral mechanisms, since other studies have shown that bolus administration of furosemide may activate this system. We therefore tested the hypothesis that continuous administration of furosemide would increase water and sodium excretion due to less activation of neurohormones. Eight patients with severe heart failure were studied during continuous infusion over 24 h and bolus injections of furosemide twice daily in a randomized cross-over study. Bolus administration of furosemide increased diuresis and natriuresis significantly in the first 4 h after administration compared with continuous administration, but this was later reversed, resulting in similar 24 h total output. The neurohormones measured at baseline were all markedly elevated. Neither regimens of furosemide caused any further significant changes in neurohumoral response except that pro-ANF decreased more during the first 8 h after bolus administration compared to continuous infusion. This study has demonstrated that bolus administration of furosemide in conventional doses is equally effective as continuous intravenous infusion in patients with severe heart failure. This may be due to maximal neurohormonal activation in severe heart failure (NYHA III-IV) which could not be further activated by bolus administration.

Complement activation during and after open-heart surgery is only marginally affected by the choice of fluid for volume replacement.

Forty patients undergoing CPB for coronary artery surgery, using a standardized technical setting, were randomized to receive either Ringer's acetate, dextran 70 (Macrodex), polygeline (Haemaccel) or albumin 4% for volume replacement during and after surgery. The choice of fluid did not affect early complement activation (C3 activation products). Higher values of the terminal complement complex (TCC) were found only at the end of the operation in patients receiving polygeline. There were no differences between any two of the four groups during the postoperative course. The use of blood transfusion or autotransfusion and the degree of haemodilution and hypothermia did not affect complement activation. We conclude that complement activation in association with open-heart surgery is only marginally affected by the choice of fluid for volume replacement.

Fluid balance and pulmonary functions during and after coronary artery bypass surgery: Ringer's acetate compared with dextran, polygeline, or albumin.

The effects on fluid balance, pulmonary functions and economics were evaluated in a randomized comparison of one colloid free and three colloid containing fluid regimens, for 48 hours during and after coronary artery bypass (CAB) surgery. A standard regimen for anaesthesia, extracorporeal circulation and monitoring was used. Only Ringer's acetate (RAc) was used as priming solution for extracorporeal circulation. Forty patients were randomized to receive either RAc, polygeline 35 mg.ml-1 (Haemaccel), dextran 70 (Macrodex) 60 mg.ml-1, or albumin 40 mg.ml-1 in saline whenever fluid volume was needed to stabilize haemodynamics. At the end of the operation, fluid retention was significantly lower in patients receiving polygeline and dextran 70, compared with patients receiving RAc. At 48 hours, however, there were no differences in cumulative fluid balance. Patients in the colloid groups postoperatively had a higher serum colloid osmotic pressure (s-COP), but a higher net lung capillary filtration pressure (delta P) only on the second postoperative day than the RAc group. However, this did not adversely affect intrapulmonary venous admixture, arterial oxygen tension, or time on respirator in the RAc group compared with the colloid groups. The most expensive colloid fluid regimen (albumin) cost about 230 US$ more per patient than the RAc fluid regimen. We conclude that Ringer's acetate for volume replacement to stabilize haemodynamics during and after CAB surgery is associated with increased fluid retention only during the intraoperative period, compared with dextran 70 or polygeline, and with a lower serum colloid osmotic pressure and net lung capillary filtration pressure postoperatively, compared with all three colloid groups. This does not affect pulmonary functions adversely.(ABSTRACT TRUNCATED AT 250 WORDS)

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, 18 degrees C compared to 36 degrees 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 (COPp) 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Colloid osmotic pressure of plasma replacement fluids.

Colloid osmotic pressure (COP) of some of the most frequently used plasma replacement fluids was measured with a colloid osmometer. COP of 4% human albumin solutions was only half that of normal human serum (13.6 +/- 0.6 vs. 27.5 +/- 2.7 mmHg (1.8 +/- 0.1 vs. 3.7 +/- 0.4 kPa)) (mean +/- s.d.), whereas COP of 20% human albumin solutions was eight times higher (196.0 +/- 12.3 mmHg (26.1 +/- 1.6 kPa)). Enhancing the protein concentration from 4% to 20% in the human albumin solutions increased COP 14-fold, reflecting the exponential relationship between protein concentration and COP of a solution. Fresh donor plasma furnished by the hospital blood-bank had a COP about 30% below normal human serum (18.1 +/- 1.3 mmHg (2.4 +/- 0.2 kPa)), due to dilution during preparation. Dextran 70 (6%) had a COP more than twice, and Ringer-Dextran 60 (3%) about 75% of that of normal human serum. Dextran 40 (10%) and gelatin (3.5%, Haemaccel) leaked markedly through the membrane of the colloid osmometer, making acceptable measurements impossible. Seven different hydroxyethyl starch (HES) solutions were measured, and the COP varied between half and 3 times that of normal human serum, depending on molecular weight and concentration of the HES.

Plasma concentrations of atrial peptides ANF(1-98) and ANF(99-126) after intravenous infusion: effect of infusate temperature.

Atrial peptides ANF(1-98) 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 immunoreactivity after infusion depended on the temperature of the infusate. The molar increase in ANF(1-98) was much larger than the increase in ANF(99-126). We speculate that plasma levels of ANF(1-98) may be a clinically useful parameter of atrial distension secondary to hypervolaemia.

Haemodynamic effects of heparin during coronary bypass surgery.

Heparin has been suggested as an activator of the plasma kallikrein-kinin system, with possible formation of bradykinin, a potent vasodilator. Haemodynamic effects and changes in the kallikrein-kinin system were studied after heparin- and saline-injections in ten patients undergoing coronary bypass surgery. A moderate decrease in mean arterial pressure was found in all patients in the observation period, but significantly more at 2 and 3 min after heparin-injection compared with saline-injection. None of the other haemodynamic variables measured were significantly different when comparing heparin- to saline-injection. Heparin-injection resulted in significant changes in the kallikrein-kinin system, with a marked increase in spontaneous kallikrein-like activity as the most prominent feature, while no changes were found after saline-injection. Liberation of bradykinin would be expected to give a decrease in systemic vascular resistance with an increase in cardiac output. The results indicate that the plasma kallikrein-kinin system, though apparently activated after heparin-injection, does not contribute significantly to the decrease in arterial pressure in the patients studied.

Autotransfusion after open heart surgery: characteristics of shed mediastinal blood and its influence on the plasma proteases in circulating blood.

Fourteen patients undergoing open-heart surgery received intermittent or continuous postoperative autotransfusion of shed mediastinal blood (minimum 400 ml during 6 h after surgery) collected in the cardiotomy reservoir. Hematologic variables and changes in the coagulation, fibrinolytic and plasma kallikrein-kinin systems were investigated in the reservoir blood at the beginning and after 6 h of autotransfusion, and in patient blood during and after surgery and before and after autotransfusion. Autotransfusion volume ranged from 400 to 1200 ml per patient (median 482 ml). The reservoir blood had a median haemoglobin level of 93 and 74 g/l, a platelet count of 71 and 119 x 10(9)/l, and plasma haemoglobin level of 3110 and 4100 mg/l before and after 6 h of autotransfusion, respectively. Further examination of the reservoir blood showed that it had undergone extensive coagulation and fibrinolysis as well as a moderate activation of the kallikrein-kinin system. Despite these extensive alterations in the reservoir blood, no major change could be found in the circulating blood after autotransfusion, except for a moderate increase in plasma haemoglobin from 180 mg/l to 430 mg/l. The clinical safety and simplicity of this technique were confirmed for autotransfusion of shed mediastinal blood up to 1200 ml.

[Jet ventilation]. / Jetventilasjon.

High frequency jet ventilation gives adequate alveolar ventilation with very small tidal volumes, gas exchange at lower airway pressure, reduced risk of pulmonary barotrauma, and less cardiovascular impairment. Use of small insufflation catheters facilitates surgery when access is restricted, as in laryngeal surgery, and makes it possible to ventilate a patient through a cricithyroid membrane puncture in an emergency situation. In intensive care medicine, jet ventilation can have some advantage over conventional ventilation in patients with bronchopleural fistulas, and when it is difficult to wean patients from a respirator. The article describes experience using an Acutronic AMS-1000 Universal Jet Ventilator.

Peroperative hypothermia.

Heat loss during anesthesia and operation and subsequent hypothermia will increase the postoperative oxygen demand and may endanger patients with restricted cardiopulmonary reserves. Forty patients scheduled for intra-abdominal aortic surgery and 40 patients scheduled for peripheral vascular surgery on the lower limbs were investigated using a warming blanket, humidified heated inspired anesthetic gases at 37-40 degrees C, or both these methods together. A fourth group of patients received no active warming. A warming blanket used alone gave no protection against hypothermia when compared with no active warming. In the abdominal surgical group, there was a steady fall in temperature throughout the operation if no warming method was employed. In this group the use of humidified, heated inspired gases was significantly better than no treatment after 2 h of anesthesia (P less than 0.05). The combination of humidified and heated inspired gases and a warming blanket gave significantly better heat preservation after 40 min (P less than 0.05). Patients undergoing peripheral vascular surgery had similar but smaller drops in temperature with the different types of warming procedures employed. The differences in temperature between the intra-abdominal and extra-abdominal operations were statistically significant after 3 h (P less than 0.05).