CT density decrease in water intoxication rat model of brain oedema.

OBJECTIVES: The aim of this study was to determine whether water intoxication affects the radiodensity of brain tissue in CT scan examination in the rat model of brain oedema. METHODS: A standard CT scan of the brain was obtained in a group of rats, first at control conditions (controls - CG) and then after hyperhydration (oedema model-EG) in the region of interest (ROI) corresponding to the area of coronary sections with pixel size 0.125 mm in position A (bregma +2.43 mm), position B (bregma -2.92 mm), position C (bregma -12.73 mm). Densitometrically determined mean values (MV), expressed in Hounsfield units (HU) were processed by standard statistical methods. RESULTS: The average MV density was 120.49±6.79 HU for the control measurement and 88.01±4.72 HU after the hyperhydration, which represents decrease in the density by 32.48 HU (p<0.001). In the control measurement the average value of HU for the position A was 121.98, for position B 112.4 and for position C 127.08. In conditions of hyperhydration, the average MV density in position A was 89.95 HU in position B 84.67 HU and in position C 89.43 HU. The differences between the CG and EG were in all positions A, B, C statistically significant (p<0.001). In the control measurement, the differences between position A×B (p<0.05) and B×C (p<0.001) were statistically significant. After hyperhydration no significant difference between the position A, B, C was found. CONCLUSION: water intoxication caused by hyperhydration in rats can induce diffuse brain oedema, which is reflected in the CT examination by the decrease of brain tissue density, expressed in HU. The value of the measured density depends on the location and size of the measured brain area.

[Acute water intoxication caused by intranasal desmopression--Minirin]. / Akut vandintoksikation forårsaget af intranasal desmopressin--Minirin.

Desmopressin is used for the treatment of nocturnal enuresis. Side effects reported with intranasal desmopressin are transient headache, nausea, abdominal cramps and water intoxication with hyponatremia and grand mal seizure. We report a case of water intoxication with low serum sodium and grand mal seizure in a healthy child treated for enuresis with desmopressin. The child experienced abdominal cramps and nausea prior to the convulsions. A computerised tomography scan of the brain gave the suspicion of increased intracranial pressure ICP. The child recovered fully. We therefore recommend that parents and child are fully informed about the administration and the risk of desmopressin. If a child on desmopressin treatment experiences abdominal cramps, nausea or headache the drug should be discontinued and a physician contacted for control of serum sodium. Temporary withdrawal of desmopressin should also be considered in cases of acute illness influencing water balance.

Lung density for assessment of hydration status in hemodialysis patients using the computed tomographic densitometry technique.

The density of the lung reflects the total mass of fluid, air, and dry lung tissue per unit volume of the lung. Lung density can be measured by evaluation of attenuation of an electron beam with computed tomography (CT). This technique has been shown to be sufficiently reliable and sensitive to distinguish normal from abnormal lung water. The aim of this study was to find out whether lung density properly reflects the hydration status in hemodialysis patients in comparison with other standard methods. Fourteen hemodialysis patients, with an ultrafiltration ranging from 0.3 to 4.5 liters per session, underwent CT measurements of lung density, ultrasonographic measurements of the diameter of the inferior vena cava after quiet expiration (IVCe) and quiet inspiration (IVCi), and measurements of the hematocrit and plasma levels of the biochemical hydration markers cyclic guanosine monophosphate (cGMP) and atrial natriuretic peptide (ANP). These measurements were performed before and 3.5 to 4 hours after termination of dialysis. Quantitative estimates of lung density were obtained within pixels with CT numbers ranging between -1000 and -100 Hounsfield Units (HU), and compared with normal data from 18 normal controls. In normal controls, the lung density ranged from -800 to -730 HU. In hemodialysis patients, lung density was significantly higher than normal before dialysis (-678 +/- 96 HU, P < 0.01) and significantly decreased after dialysis (-706 +/- 92 HU, P < 0.05), indicating a decrease in fluid content of the lung. The density was normalized in 5 patients. A significant correlation was found between lung density and IVCe both before and after dialysis (r = 0.8, P < 0.01 for both). Change in density was significantly correlated to amount of ultrafiltration (r = 0.67, P < 0.01) and percent change in blood volume (r = 0.63, P < 0.05), indicating that lung density is greatly affected by changes in the extracellular fluid volume, mainly the intravascular volume. In conclusion, lung water reflects the hydration status in hemodialysis patients and can be monitored by measuring the lung density by CT. Accordingly, normalization of lung density can help to achieve a proper dry weight in these patients.

Water intoxication and rhabdomyolysis.

A 44-year-old woman was admitted because of stupor. She had consumed 3 liters of water due to thirst after drinking alcohol. Laboratory findings on admission revealed marked hyponatremia (sodium: 115 mEq/l). She was diagnosed as having water intoxication. She recovered from her hyponatremia upon excretion of a large amount of hypotonic urine. Subsequently, however, her serum creatine phosphokinase was markedly elevated at 28,650 IU/l, and her serum myoglobin reached 2,760 ng/ml. The relationship between the occurrence of hyponatremia secondary to water intoxication and rhabdomyolysis was suggested.