Preoperative serum sodium measurements and postoperative inpatient mortality: A case-control analysis of data from the South African Surgical Outcomes Study

Background. Abnormal preoperative serum sodium measurements have been shown to be associated with increased postoperative mortality in US and European surgical populations. It is possible that such measurements are also associated with increased postoperative mortality in a South African (SA) setting, but this is yet to be confirmed. Establishing whether preoperative serum sodium measurements are associated with postoperative mortality could have implications for perioperative risk stratification in SA settings.Objectives. To determine whether preoperative serum sodium measurements are associated with postoperative mortality in SA surgical patients.Methods. This was an unmatched case-control study of patient data (demographics, comorbidities, procedure-related variables, and preoperative serum sodium measurements) collected during the South African Surgical Outcomes Study. Data were analysed using recommended statistical methods for unmatched case-control studies.Results. The study population comprised 103 patients and 410 controls. Cases were defined as patients who suffered postoperative inpatient mortality, while controls were defined as patients who did not suffer postoperative inpatient mortality. Preoperative hypernatraemia (i.e. a preoperative serum sodium measurement >144 mEq/L) was independently associated with a four-fold higher risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement of 135 - 144 mEq/L (odds ratio (OR) 4.21, 95% confidence interval (CI) 1.19 - 14.83, p=0.025). Preoperative hyponatraemia (i.e. a preoperative serum sodium measurement <135 mEq/L) was not independently associated with a higher or lower risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement (OR 1.39, 95% CI 0.70 - 2.76, p=0.346).Conclusions. Preoperative hypernatraemia, but not preoperative hyponatraemia, is a risk factor for postoperative inpatient mortality in SA surgical patients

Evaluation des dysnatremies au cours de la deshydratation aigue de l'enfant au Centre Hospitalier National d'Enfants Albert Royer (CHNEAR) de Dakar

INTRODUCTION : La deshydratation aigue represente une urgence pediatrique courante; generalement secondaire a la diarrhee aigue. L'objectif de cette etude etait d'apprecier; au cours de la deshydratation aigue; la prevalence des dysnatremies; leur impact sur la morbi-mortalite et les implications therapeutiques dans la prise en charge.MATERIEL ET METHODES : Il s'agissait d'une etude retrospective menee sur deux ans (2009 a 2010); au Centre National Hospitalier d'Enfants Albert Royer; incluant tous les enfants de 2 mois a 5 ans; souffrant de deshydratation aigue et ayant eu un ionogramme sanguin. Sur 310 cas de deshydratation recenses; 205 dossiers repondaient aux criteres d'inclusion et ont constitue notre population d'etude. Nous avons recueilli les donnees epidemiologiques; cliniques; biologiques; therapeutiques et evolutives. Nous avons retenu la classification de la deshydratation en legere; moderee et severe qui figurait dans le dossier. L'hyponatremie etait definie par une natremie strictement inferieure a 135 mmol/l; l'hypernatremie par une natremie superieure a 150 mmol/l. L'analyse a ete faite sur Epi info 3.5. Un p 0.05 etait considere comme significatif. RESULTATS : L'incidence de la deshydratation etait de 3;78%. L'age moyen etait de 12.2 mois (2 a 48 mois) et le sex ratio de 1;52 en faveur des garcons. Il y avait deux pics d'hospitalisation; en janvier-fevrier et en septembre. Un trouble digestif (diarrhee ou vomissements) etait present chez 202 enfants (98;5%) et la denutrition chez 35 enfants (17;1%). La gastroenterite aigue (159 cas) representait 77;5% des causes. La deshydratation etait jugee legere dans 20 cas (9;7 %); moderee dans 91 cas (44;4%) et severe [JK1] dans 94 cas (45;8%). [JK2] L'hyponatremie etait presente chez 105 enfants (51;2%) et elle etait severe; inferieure a 125 mmol/l; chez 28 (13;7%). L'hypernatremie etait notee chez 15 enfants (7;3%). Quatre-vingt pour cent des hypernatremies et 51;5% des hyponatremies etaient associees a une deshydratation severe (P

The renal concentrating mechanism and the clinical consequences of its loss

The integrity of the renal concentrating mechanism is maintained by the anatomical and functional arrangements of the renal transport mechanisms for solute (sodium; potassium; urea; etc) and water and by the function of the regulatory hormone for renal concentration; vasopressin. The discovery of aquaporins (water channels) in the cell membranes of the renal tubular epithelial cells has elucidated the mechanisms of renal actions of vasopressin. Loss of the concentrating mechanism results in uncontrolled polyuria with low urine osmolality and; if the patient is unable to consume (appropriately) large volumes of water; hypernatremia with dire neurological consequences. Loss of concentrating mechanism can be the consequence of defective secretion of vasopressin from the posterior pituitary gland (congenital or acquired central diabetes insipidus) or poor response of the target organ to vasopressin (congenital or nephrogenic diabetes insipidus). The differentiation between the three major states producing polyuria with low urine osmolality (central diabetes insipidus; nephrogenic diabetes insipidus and primary polydipsia) is done by a standardized water deprivation test. Proper diagnosis is essential for the management; which differs between these three conditions