Postoperative water and electrolyte changes in skeletal muscle: a clinical study with three different intravenous infusions

Perioperative fluid management in renal transplantation: a narrative review of the literature

Adequate volume maintenance is essential to prevent acute renal failure during major surgery or to ensure graft function after renal transplantation. The various recommendations on the optimum fluid therapy are based, at best, on sparse evidence only from observational studies. This article reviews the literature on perioperative fluid management in renal transplantation. Crystalloid solutions not exerting any specific side-effects are the first choice for volume replacement in kidney transplantation. The use of colloids should be restricted to patients with severe intravascular volume deficits necessitating high volume restoration. The routine application of albumin, dopamine, and high dose diuretics is no longer warranted. Mannitol given immediately before removal of the vessel clamps reduces the requirement of post-transplant dialysis, but has no effects on graft function in the long term. There is insufficient evidence on the best use of dialysis, but it seems peritoneal dialysis pretransplant is associated with less delayed graft function, whereas the preference of dialysis post-transplant is not yet well-founded. This review article should provide better guidance for fluid management in kidney transplantation until best-evidence guidelines can be established based upon more research.

Preventing neurological complications from dysnatremias in children

Dysnatremias are among the most common electrolyte abnormalities encountered in hospitalized patients. In most cases, a dysnatremia results from improper fluid management. Dysnatremias can occasionally result in death or permanent neurological damage, a tragic complication that is usually preventable. In this manuscript, we discuss the epidemiology, pathogenesis and prevention and treatment of dysnatremias in children. We report on over 50 patients who have suffered death or neurological injury from hospital-acquired hyponatremia. The main factor contributing to hyponatremic encephalopathy in children is the routine use of hypotonic fluids in patients who have an impaired ability to excrete free-water, due to such causes as the postoperative state, volume depletion and pulmonary and central nervous system diseases. The appropriate use of 0.9% sodium chloride in parenteral fluids would likely prevent most cases of hospital-acquired hyponatremic encephalopathy. We report on 15 prospective studies in over 500 surgical patients that demonstrate that normal saline effectively prevents postoperative hyponatremia, and hypotonic fluids consistently result in a fall in serum sodium. Hyponatremic encephalopathy is a medical emergency that should be treated with hypertonic saline, and should never be managed with fluid restriction alone. Hospital-acquired hypernatremia occurs in patients who have restricted access to fluids in combination with ongoing free-water losses. Hypernatremia could largely be prevented by providing adequate free-water to patients who have ongoing free-water losses or when mild hypernatremia (Na>145 mE/l) develops. A group at high-risk for neurological damage from hypernatremia in the outpatient setting is that of the breastfed infant. Breastfed infants must be monitored closely for insufficient lactation and receive lactation support. Judicious use of infant formula supplementation may be called for until problems with lactation can be corrected.

Perioperative fluid management and clinical outcomes in adults

The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the physicochemical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults.

Volume kinetics of glucose 2.5% solution and insulin resistance after abdominal hysterectomy

BACKGROUND

We hypothesized that volume kinetics can be used to predict the rate of infusion of glucose 2.5% solution required to yield any predetermined plasma glucose level and degree of plasma dilution during the postoperative period.

METHODS

In 15 women, mean age 50 yr (range 37-63), 2 days after an abdominal hysterectomy, a volume kinetic analysis was performed on an i.v. infusion of 12.5 ml kg(-1) ( approximately 900 ml) of glucose 2.5% given over 45 min. The insulin resistance was measured by a glucose clamp, and it was compared with daily bioimpedance analyses, which indicated the hydration of the intra/extracellular body fluid spaces.

RESULTS

The clearance of glucose was 0.42 litre min(-1) (0.60 litre min(-1) is normal) while the other five parameters in the kinetic model were similar to those obtained in healthy volunteers. Computer simulations indicated that in a 70-kg female, at steady state, the rate of infusion (ml min(-1)) should be three times the allowed increase in plasma glucose (mmol litre(-1)). To maintain a predetermined plasma dilution the corresponding rate factor was 160. The glucose uptake during clamping was 3.9 mg kg(-1) min(-1) (7.0 is normal), which, during the second day after hysterectomy, correlated with the dehydration of the intracellular space (r=0.77; P<0.002) and with the protein catabolism as indicated by the urinary excretion of 3-methylhistidine (r=-0.76, P<0.002).

CONCLUSION

The anaesthetist can prescribe postoperative administration of glucose 2.5% to reach any desired plasma glucose level and dilution by using the two presented nomograms. Insulin resistance correlated with intracellular dehydration and protein catabolism.

Validation of volume kinetic analysis of glucose 2.5% solution given by intravenous infusion

BACKGROUND

The distribution and elimination of glucose solutions can be analysed by means of a volume kinetic model, but the ability of the model to predict plasma dilution ('model linearity') has not been evaluated.

METHODS

Six male volunteers received four separate infusions of glucose 2.5%: 10 ml kg(-1) and 15 ml kg(-1) over 30 min, and 15 ml kg(-1) and 25 ml kg(-1 )over 60 min. The kinetic model was fitted to measurements of plasma glucose concentration and haemodilution.

RESULTS

The mean volume of distribution for the glucose was 9.2 (SEM 0.4) litres while the infused fluid expanded a central body fluid space (V(1)) of 3.1 (0.3) litres. Increasing the amount of infused fluid, but not the infusion rate, resulted in a proportional increase in the area under the curve for plasma glucose and plasma dilution, the only confounder being glycosuria. The bias of computer simulation was slightly increased by rebound hypoglycaemia, which could occur with the highest infusion rates, but the accuracy was almost identical regardless of whether the kinetic parameters from all 24 experiments or from any of the subgroups were used.

CONCLUSION

The volume kinetic model for glucose 2.5% is linear and can therefore be used for computer simulation as long as marked glycosuria does not occur.

Free amino acids in plasma and muscle during 24 hours post-operatively--a descriptive study

Intracellular amino acids in skeletal muscle show a specific concentration pattern on the third post-operative day. The temporal development of these changes has not been clarified. Here the amino acid concentrations in skeletal muscle were studied during the first post-operative day in fourteen patients undergoing elective abdominal surgery. Muscle amino acids were determined pre-operatively, as well as at 12 and 24 h post-operatively. In muscle the concentrations of glutamine and the basic amino acids decreased gradually during the first 24 h after surgery to 79% (P less than 0.001) and 67% (P less than .001) respectively. The sum of the essential amino acids decreased to 73% (P less than 0.001) at 12 h, but thereafter rose to 91% (P less than 0.05) at 24 h. The sum of the BCAA decreased to 84% (P less than 0.05) at 12 h but then increased to 116% (P less than 0.05) at 24 h. The alanine concentration increased to 122% (P less than 0.001) during the first post-operative day. In plasma the alanine concentration increased at 12 h while most other amino acids declined. At 24 h post-operatively the plasma concentrations of all amino acids had returned to normal or showed a tendency towards normalization except for phenylalanine, which increased. At the end of the first post-operative day the concentrations of amino acids in muscle were consistent with the alterations previously observed three days after surgery. The changes in plasma amino acid concentrations only partly reflected those in muscle.

O6-methylguanine-DNA methyltransferase content in human lymphocytes following surgical trauma

O6-methylguanine-DNA methyltransferase removes methyl groups from the O-6 position of guanine in DNA previously alkylated by alkylating carcinogens. Thus, the protein facilitates restoration of the impaired DNA. The content of O6-methylguanine-DNA methyltransferase was assayed in circulating lymphocytes and the impact of surgical trauma investigated. Patients (n = 13) without metabolic diseases admitted for elective orthopedic surgery were used. The patients were allowed water and food postoperatively. Blood was taken before and 3 days following surgery and the circulating lymphocytes were isolated. Before surgery, the O6-methylguanine-DNA methyltransferase content determined in the cell extracts showed patient-specific variations. Following surgery, a significant decrease of the protein by 60% (from 609 to 243 fmole/mg of DNA) was observed. The intensity of surgical trauma was confirmed by the decrease in plasma albumin concentration and the increase in white blood cell counts. The surgical trauma might elicit its effect as either a change in turnover of O6-methylguanine-DNA methyltransferase or a release from the thymus of lymphocytes low in enzyme levels. In summary, the surgical trauma per se was the cause of the pronounced decrease in the O6-methylguanine-DNA methyltransferase seen here. Investigations on O6-methylguanine-DNA methyltransferase levels have an important relevance in studies on tumor-promoting agents inhaled and then taken up by the T lymphocytes of prospective proliferating capacity.