[Perioperative fasting in children: current data]

[Postoperative hyponatremia in children: pathophysiology, diagnosis and treatment]

OBJECTIVES

To review the current data on pathophysiology, causes and management of postoperative hyponatremia in children.

DATA SOURCES AND EXTRACTION

The Pubmed database was searched for articles, combined with references analysis of major articles on the field.

DATA SYNTHESIS

The incidence of postoperative hyponatremia has been evaluated at 0.34% and its mortality significant. Postoperative hyponatremia is triggered by the diminished renal ability to excrete free water, due to antidiuretic hormone release. Inappropriate secretion of antidiuretic hormone is frequently seen after spine, cardiac and neurosurgery but can occur even after minor surgery. In this context, the infusion of hypotonic fluids represents a strong risk factor for developing hyponatremia. Other causes of hyponatremia are represented by extrarenal fluid losses, cerebral salt wasting syndrome, desalination phenomenon, adrenal insufficiency or some medications. Preventive treatment is essential and based on prohibition of hypotonic fluids infusion and the use of isotonic fluids infusions, maintenance of a normal total blood volume, the observance of the good practice recommendations for fluid infusion in children, and frequent blood and urine sodium concentration determinations in patients at risk for developing hyponatremia. Hyponatremic encephalopathy requires an emergent management, consisting in respiratory care and hypertonic sodium chloride infusion. Chronic hyponatremia is most often asymptomatic and the main neurological risk factor is represented by a too rapid correction of plasma sodium, which may lead to centropontine myelinolysis.

[Severe hyponatremic encephalopathy after pediatric surgery: report of seven cases and recommendations for management and prevention]

BACKGROUND

The infusion of hypotonic solutions in the perioperative period can lead to the development of hyponatraemic encephalopathy which is a severe, life threatening but preventable complication.

CLINICAL PRESENTATION

Seven children aged 3-6 yr, ASA 1 or 2, operated on for a scheduled surgical procedure, presented at the 11th postoperative hour with seizures or status epilepticus, associated with vomiting (5/7), and a constant loss of consciousness (median Glasgow Coma Scale at 7), while one child presented with a respiratory arrest. At arrival in ICU, serum sodium was 120 mmol.L-1. All children had received in the perioperative period an hypotonic solution infusion (mainly dextrose 5%), at a high rate for most of them. Management included mechanical ventilation (3/7), antiepileptic drugs (7/7), fluid restriction (7/7), sodium chloride infusion (5/7), and diuretics (6/7). Serum sodium increased to a mean of 135 mmol.L-1 in 12 hours. Six children had a good neurologic outcome while one child died from brain death.

CONCLUSION

The use of hypotonic solute in the perioperative period can lead to hyponatremic encephalopathy, a severe neurologic complication of acute hyponatremia. It must be prevented by the use of appropriate solutions i-e isotonic fluids in regards of the low free water elimination capacities of the surgical patient.

Should adult patients drink fluids before discharge from ambulatory surgery?

We studied 726 consenting patients to determine whether withholding oral fluids from adult ambulatory surgical patients before discharge would decrease the incidence of postoperative nausea and vomiting (PONV) and shorten the duration of stay in the ambulatory surgery unit (ASU). Patients were randomly assigned to the drinking or nondrinking group. Both groups received a standard regimen of general anesthesia, fluid replacement, and analgesia. In the ASU, patients in the drinking group were given mandatory oral fluids to drink before discharge. Nausea and pain were assessed by using a visual analog scale 15, 30, 60, 90, 105, 120, 150, and 180 min postoperatively. The time to drink, sit up, void, and ambulate, and the time until discharge were recorded. Patients were interviewed by telephone 24 h postoperatively. There was no significant difference in the frequency of PONV between the drinking and the nondrinking groups either in the hospital or after discharge. Patients in the drinking group required more time to begin ambulating (105 +/- 38 vs 98 +/- 34 min; P < 0.02) and to void (112 +/- 40 vs 105 +/- 37 min; P < 0.01). Patients in the drinking group also stayed in the ASU longer (85 +/- 49 vs 81 +/- 47 min; P < 0.03). Time to postanesthetic discharge was also significantly longer in the drinking group than the nondrinking group (106 +/- 40 vs 98 +/- 36 min; P < 0.015). A similar percentage of patients in both groups were "very satisfied" with their ambulatory surgical care. There was no difference in postoperative complications and need for medical help. Withholding early postoperative oral fluids facilitated earlier ambulation and decreased the stay in the ASU but did not decrease the incidence of PONV. Thus, in this ambulatory surgical population, there does not seem to be justification to require drinking before discharge.

IMPLICATIONS

To answer the question of whether adult outpatients should drink before discharge after minor surgical procedures, 726 patients were randomized to either drink approximately 150 mL of liquid or not to drink. Neither drinking nor nondrinking worsened postoperative nausea or vomiting or prolonged hospital stay. Therefore, patients should be allowed to choose whether they drink before discharge.

Perioperative thirst: a patient perspective

Many institutions continue to require surgery patients to take nothing by mouth after midnight despite current research that supports allowing most patients to drink fluids up to 3 hours before surgery. This study of 50 elective surgery patients describes their perceptions of discomfort caused by thirst. Results show that thirst caused significantly more discomfort to the patient than not being able to eat or sleep or worrying about the surgery itself. Given these results, nurses are urged to work within their institutions to change the current practice regarding preoperative fluid restriction.