HHNS is an acute complication of diabetes mellitus (particularly type 2 diabetes) characterized by hyperglycemia, dehydration, and hyperosmolarity, but little or no ketosis.
Pathophysiology and Etiology
- Prolonged hyperglycemia with glucosuria produces osmotic diuresis.
- Loss of water, sodium, and potassium results in severe dehydration, causing hypovolemia and hemoconcentration.
- Hyperosmolarity is a result of excessive blood sugar and increasing sodium concentration in dehydration.
- Insulin continues to be produced at a level that prevents ketosis.
- Increased blood viscosity decreases blood flow to the organs, creating tissue hypoxia.
- Intracellular fluid and electrolyte shifts produce neurologic signs and symptoms.
- Caused by inadequate amounts of endogenous/exogenous insulin to control hyperglycemia.
- Precipitating event may occur, such as cardiac failure, burn, or chronic illness that increases need for insulin.
- Use of therapeutic agents that increase blood glucose levels (eg, glucocorticoids, immunosuppressive agents).
- Use of therapeutic procedures that cause stress or increase blood glucose levels (eg, hyperosmolar hyperalimentation, peritoneal dialysis).
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Clinical Manifestations
Early
- Polyuria, dehydration
- Fatigue, malaise
- Nausea, vomiting
Later
- Hypothermia
- Seizures, stupor, coma
- Muscle weakness
Diagnostic Evaluation
- Serum glucose and osmolality are greatly elevated.
- Serum and urine ketone bodies are minimal to absent.
- Serum sodium and potassium levels may be elevated, depending on degree of dehydration, despite total body losses.
- BUN and creatinine may be elevated due to dehydration.
- Urine specific gravity is elevated due to dehydration.
Management
- Correct fluid and electrolyte imbalances with I.V. fluids.
- Provide insulin via I.V. drip to lower plasma glucose.
- Evaluate complications, such as stupor, seizures, or shock, and treat appropriately.
- Identify and treat underlying illnesses or events that precipitated HHNS.
Complications
- Too rapid infusion of I.V. fluids can cause cerebral edema and death.
- HHNS is a medical emergency that, if not treated properly, can cause death.
- Patients who become comatose will need nasogastric (NG) tubes to prevent aspiration.
Nursing Assessment
- Assess level of consciousness (LOC).
- Assess for dehydration—poor turgor, flushing, dry mucous membranes.
- Assess cardiovascular status for shock—rapid, thready pulse, cool extremities, hypotension, electrocardiogram changes.
- Interview family or significant other regarding precipitating events to episode of HHNS.
- Evaluate patient's self-care regimen before hospitalization.
- Determine events, treatments, or drugs that may have caused the event.
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Nursing Diagnoses
- Deficient Fluid Volume related to severe dehydration
- Risk for Aspiration related to reduced LOC and vomiting
Nursing Interventions
Restoring Fluid Balance
- Assess patient for increasing signs and symptoms of dehydration, hyperglycemia, or electrolyte imbalance.
- Institute fluid replacement therapy as ordered (usually normal or half-strength saline initially), maintaining patent I.V. line.
- Assess patient for signs and symptoms of fluid overload and cerebral edema as I.V. therapy progresses.
- Administer regular insulin I.V. as ordered, and add dextrose to I.V. infusion as blood glucose falls below 300 mg/dL, to prevent hypoglycemia.
- Monitor hydration status by monitoring hourly intake and output and urine specific gravity.
Preventing Aspiration
- Assess patient's LOC and ability to handle oral secretions.
- Cough and gag reflex
- Ability to swallow
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- Properly position patient to reduce possibility of aspiration.
- Elevate head of bed unless contraindicated.
- If nausea is present, use side-lying position.
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- Suction as frequently as needed to maintain patent airway.
- Withhold oral intake until patient is no longer in danger of aspiration.
- Insert NG tube as indicated for gastric decompression.
- Monitor respiratory rate and breath sounds for signs of aspiration pneumonia.
- Provide mouth care to maintain adequate mucosal hydration.
Patient Education and Health Maintenance
- Advise the patient and family that it may take 3 to 5 days for symptoms to resolve.
- Instruct the patient and family in signs and symptoms of hyperglycemia and use of sick-day guidelines
- Explain possible causes of HHNS.
- Review changes in medication, activity, meal plan, or glucose monitoring for home care. It may not be necessary to continue insulin therapy following HHNS; many patients can be treated with diet and oral agents.
Evaluation: Expected Outcomes
- BP stable, dehydration resolved
- No evidence of aspiration
