Hemorrhage in normal man. II. Effects of mannitol on plasma volume and body water dynamics following acute blood loss

Advances in the Starling Principle and Microvascular Fluid Exchange; Consequences and Implications for Fluid Therapy

Ernest Starling first presented a hypothesis about the absorption of tissue fluid to the plasma within tissue capillaries in 1896. In this Chapter we trace the evolution of Starling's hypothesis to a principle and an equation, and then look in more detail at the extension of the Starling principle in recent years. In 2012 Thomas Woodcock and his son proposed that experience and experimental observations surrounding clinical practices involving the administration of intravenous fluids were better explained by the revised Starling principle. In particular, the revised or extended Starling principle can explain why crystalloid resuscitation from the abrupt physiologic insult of hypovolaemia is much more effective than the pre-revision Starling principle had led clinicians to expect. The authors of this chapter have since combined their science and clinical expertise to offer clinicians a better basis for their practice of rational fluid therapy.

Plasma volume expansion from the intravenous glucose tolerance test before and after hip replacement surgery

BACKGROUND

Hyperosmotic glucose is injected intravenously when an intravenous glucose tolerance test (IVGTT) is initiated. The extent and time period of plasma volume expansion that occurs in response to the glucose load has not been studied in the perioperative setting.

METHODS

Twenty-two non-diabetic patients aged between 57 and 76 years (mean 68) underwent an IVGTT, during which 0.3 g/kg of glucose 30% (1 ml/kg) was injected as a bolus over one minute, one day before and two days after hip replacement surgery. Twelve blood samples were collected over 75 minutes from each patient. The turnover of both the exogenous glucose and the injected fluid volume was calculated by means of mass balance and volume kinetic analysis.

RESULTS

The IVGTT raised plasma glucose by 9 mmol/L and the plasma volume by 8%. The extracellular fluid volume increased by 320 (SD 60) ml of which 2/3 could be accounted for in the plasma. The half-life of the exogenous glucose averaged 30 minutes before surgery and 36 minutes postoperatively (P < 0.02). The glucose elimination governed 86% of the decay of the plasma volume expansion, which occurred with a half-life of 12 minutes before to 21 minutes after the surgery (median, P < 0.001).

CONCLUSION

Hyperosmotic glucose translocated intracellular water to the plasma volume rather than to the entire extracellular fluid volume. The preferential re-distribution acts to dilute the plasma concentrations used to quantify insulin sensitivity and ß-cell function from an IVGTT. The greater-than-expected plasma dilution lasted longer after than before surgery.

The influence of mannitol on renal function during and after open-heart surgery

Mannitol is often included in the priming solution of the heart-lung machine used during cardiopulmonary bypass (CPB). This study was set up to evaluate the effect of different doses of mannitol on human patients. Patients receiving 10 g of mannitol (n = 18) had an increased diuresis only during the bypass period (mean time = 87 min) when compared with a control group (n = 19) who did not receive mannitol. Patients receiving 20 g of mannitol (n = 19) had a significantly greater diuresis than both the control group and the 10 g group and the diuresis continued on throughout the immediate postbypass period (total mean time approximately 3 h). Patients receiving 30 g of mannitol (n = 20) also had a significantly greater diuresis that continued on during the first hour in the intensive care unit (ICU) (total mean time approximately 4 h). After 6 h in the ICU, all three groups of mannitol-treated patients equally demonstrated a trend towards an increased diuresis over the control group, which became a significant increase by 12 h in the ICU (p = 0.001) despite indications that the mannitol had been cleared from the body. These results suggest that there is an improvement of renal function post-CPB if mannitol is included in the CPB prime which may be due to an amelioration of the ischaemic effects of bypass on the kidneys.

Intravenous infusion of irrigating fluids containing glycine or mannitol with and without ethanol

Irrigating fluids consisting of 5% mannitol, 3% mannitol + 1% ethanol, 2.2% glycine and 1.5% glycine + 1% ethanol in water were given by intravenous infusion to seven healthy volunteers at a constant rate of 50 ml./min. over 20 min. The irrigants containing glycine produced hyperkalemia and usually prickling and burning skin sensations and slight nausea. The severity of the symptoms apparently correlated to the blood ammonia level, which increased significantly after the glycine but not after the mannitol infusions. With 5% mannitol, there was a pronounced transient increase of the blood volume and a prolonged hyponatremia. There were no differences between the irrigants in respect to their effects on blood pressure and urine excretion. Ethanol caused no adverse effects and allowed the fluid supplementation to be followed by expired breath tests.

Blood volume during transurethral prostatic resection

The variations in blood volume (BV), occurring in the course of 61 transurethral prostatic resections and estimated by the haemoglobin dilution method, were examined in relation to the type and volume of i.v. fluid given, the amount of irrigant absorbed and the blood loss. When dextran 40 was used (n = 16), the BV increased within 10 min by 2.7 times the volume infused, while for cumulative data relating to several 10-min periods in the course of surgery this factor was 1.3; for acetated Ringer solution (n = 45), the respective values were 0.5 and 0.3-0.4. The half-life of absorbed irrigating fluid in the circulation was between 5 and 10 min. In patients receiving dextran 40 the BV decreased by the volume of blood lost; however, when acetated Ringer solution was given, the BV decreased by only 60% of the blood loss.

Hemodynamic effect of mannitol in a canine model of concomitant increased intracranial pressure and hemorrhagic shock

The use of mannitol in the management of head injury has been considered a threat to hemodynamic stability in hypotensive multiply injured patients. To evaluate this contention, we compared mannitol with normal saline administration in a canine model combining elevated intracranial pressure (ICP) and hemorrhagic shock. Mongrel dogs were bled to and maintained at a mean arterial pressure (MAP) of 60 mm Hg for 30 minutes. Following this, ICP was elevated to and sustained at 25 mm Hg for 45 minutes by inflating an epidural balloon. The dogs were then randomized to resuscitation with 2 g/kg of mannitol in saline (total volume, 20 mL/kg; n = 5) or 20 mL/kg of normal saline alone (n = 5). All dogs were successfully resuscitated, and MAP returned to baseline levels in both groups. ICP was significantly lower and urine output significantly higher in the mannitol group than in saline controls (P less than .01). Moreover, cerebral perfusion pressure, cardiac index, and left ventricular stroke work index were significantly improved in dogs given mannitol versus controls during the first hour of resuscitation (P less than .05). Mannitol ameliorates increases in ICP without compromising hemodynamic resuscitation in a canine model of concomitant increased ICP and shock.

Effects of single, repeated and massive mannitol infusion in the dog: structural and functional changes in kidney and brain

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Hemorrhage in normal man. I. distribution and dispersal of saline infusions following acute blood loss: clinical kinetics of blood volume support

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