Hyperglycemia exists when the blood glucose level is greater than 110 mg/dL. Normal blood glucose levels can be maintained between 70 and 110 mg/dL when there is an adequate balance between insulin supply and demand. In acutely ill individuals, hyperglycemia is usually not diagnosed until a random test of serum glucose level shows an increase above the 150 to 200 mg/dL range. Glucose is the most important carbohydrate in body metabolism. It is formed from the breakdown of polysaccharides, especially starch, and is absorbed from the intestines into the blood of the portal vein. As it passes through the liver, glucose is converted into glycogen for storage, but the body maintains a blood level for tissue needs.
Insulin is produced by the beta cells of the pancreas, which are stimulated to release it when the blood glucose level rises. Insulin transports glucose, amino acids, potassium, and phosphate across the cell membrane. Insufficient production or ineffective use of insulin causes an elevated blood glucose level (hyperglycemia), which promotes water movement into the bloodstream from the interstitial space and intracellular fluid compartments. As blood glucose levels increase, the renal threshold for glucose reabsorption is exceeded, and glycosuria (loss of glucose in the urine) occurs. Glucose in the urine acts as an osmotic diuretic, and the patient has an increased urinary output in response that can lead to a serious fluid volume deficit. As glucose levels climb, the blood becomes more viscous and the patient is also at risk for thromboembolic phenomena.
Insulin resistance and hyperglycemia has been linked with any critical illness or traumatic injury, and has been named the “diabetes of injury.” Current research has found links between hyperglycemia and poor outcomes from acute illnesses and trauma. Current thinking is that with better control of hyperglycemia, patient outcomes may improve during an acute illness.
The two primary causes of hyperglycemia are diabetes mellitus and hyperosmolar nonketotic syndrome (HNKS). Other conditions that can lead to hyperglycemiainclude glucocorticoid imbalances (Cushing’s syndrome), increased epinephrine levels during times of extreme stress (multiple trauma, surgery), excess growth hormone secretion, excessive ingestion or administration of glucose by total parenteral nutrition or enteral feedings, and pregnancy. In patients with extreme physiological stress, such as thermal injuries, multiple trauma, or shock, a serum glucose of approximately 200 to 250 mg/dL is expected, considering the release of epinephrine that accompanies the stress response.
Nursing care plan assessment and physical examination
Ascertain if the patient has any disorders that are risk factors for hyperglycemia. Elicit a complete medication history, focusing on whether the patient has ever taken insulin or oral antidiabetic medications. Ask about polyuria (excessive urination) and polydypsia (excessive thirst). Because it is common to have large amounts of dilute urine, ask if the patient has noted a larger urinary output than usual and if the color was light yellow or clear.
The patient may not have any symptoms unless the blood glucose level has increased high enough to cause fluid volume deficit and dehydration. Perform a complete head-to-toe assessment, including a neurological examination. Patients with severe hyperglycemia also have an increased serum osmolarity (higher concentration of particles than water in the blood); when it goes above 300 mOsm/L, osmolarity causes decreased mental status. Assess the patient’s level of consciousness and the cough and gag reflexes. Inspect for signs of dehydration: dry mucous membranes, poor skin turgor, and dry scaly skin. Press gently on the patient’s eyeballs; they may feel soft rather than firm. The patient’s vital signs may reveal hypotension from fluid loss and tachycardia. If the dehydration has occurred for several days, the patient may have warm skin and an elevated temperature. In spite of the state of dehydration, the urine may not appear concentrated.
Ask about the home environment, occupation, knowledge level, financial situation, and support systems, which may provide information that can be used to prevent future episodes. Determine the patient’s and significant other’s social, economic, and interpersonal resources to help manage a potentially chronic condition such as diabetes mellitus.
Nursing care plan primary nursing diagnosis: Fluid volume deficit related to excess urinary output.
Nursing care plan intervention and treatment plan
If the serum glucose level is above 250 mg/dL and the fluid balance is adequate, insulin is usually prescribed either as a subcutaneous (SC) injection or as an intravenous (IV) push injection. Often patients are placed on a “sliding scale” of insulin every 6 hours. If a patient has an elevated serum glucose along with a fluid volume deficit, the fluid volume deficit is corrected first, often with normal saline solution (0.9% sodium chloride), before the glucose excess. If glucose is reduced on a fluid volume–depleted patient before volume resuscitation, the vascular volume decreases and the patient can develop hypovolemic shock. If the patient has hyperglycemia because of diabetes mellitus or HNKS, management is based on the severity of her or his symptoms. Because HNKS is associated with extraordinarily high levels of glucose (some reports describe levels higher than 1000 mg/dL), the patient usually requires volume resuscitation followed by an insulin infusion. Often patients receive intermittent SC or IV doses of insulin as well. This should be done cautiously, however, because if the serum glucose level is reduced too rapidly, fluid shifts into the central nervous system, leading to cerebral edema and death. No matter what the diagnosis, once the glucose level and the patient are stabilized, a full workup to determine the cause and long-term treatment is needed to prevent recurrences of hyperglycemia.
Current thinking with acutely and critically ill patients, in particular surgical patients, is that patient outcomes can be improved with more stringent control of hyperglycemia than in the past. The goal of control during the critical illness is a glucose level in the range of 80 to 125 mg/dL. Frequent, serial glucose monitoring at the bedside as frequently as every 30 minutes with pointof- care technology may be necessary during the administration of insulin through continuous insulin infusions.
The first priority is to maintain adequate fluid balance. The action of glucose as an osmotic diuretic places the patient at risk for severe fluid volume deficits. If he or she is awake, encourage the patient to drink water and sugar-free drinks without caffeine. Because patients are usually tachycardic, caffeinated beverages are contraindicated. Because severe hyperglycemia is accompanied by increased serum osmolarity and accompanying decreases in mental status, fluid replacement is accomplished by the IV route in most cases. If rapid fluid resuscitation is needed, use a large-gauge peripheral IV site with a short length to provide for rapid fluid replacement. Keep the tubing as short as possible from the IV bag or bottle, and avoid long loops of tubing at a level below the patient’s heart. Monitor for signs of underhydration (mental status that remains depressed, dry mucous membranes, soft eyeballs) and overhydration (pulmonary congestion, neck vein distension, shortness of breath, frothy sputum, cough).
Patients with the most severe cases of hyperglycemia have a risk of ineffective airway clearance because of decreased mental status and airway obstruction by the tongue. Have airway equipment near the patient’s bedside at all times, including an oral and nasal airway, an endotracheal tube, and a laryngoscope. If the patient develops snoring, slow respirations, or apnea, maintain the patient’s airway and breathing with a manual resuscitator bag and notify the physician immediately.
If the patient has hyperglycemia because of diabetes mellitus or HNKS, provide appropriate patient teaching. Discuss the administration of insulin; a consistent and appropriate technique of insulin administration is critical for optimal blood glucose control. Whenever possible, have the patient administer her or his own insulin. Encourage exercise. Instruct the patient about self-monitoring to recognize the signs and symptoms of hyperglycemiaand hypoglycemia. Teach the patient and significant others how to prevent skin and lower-extremity infection, ulcers, and poor wound healing.
Nursing care plan discharge and home health care guidelines
Teach the patient strategies for managing the disorder. Provide a written list of all medications, including dosage, route, time, and side effects. If appropriate, give the patient a phone number to call if he or she has any problems with self-administration of insulin or self-monitoring of blood glucose. Provide the patient with a list of referrals, such as an outpatient diabetic clinic or community contacts, for follow-up care and information. Provide a list of equipment and materials needed for home care. Give the patient any pamphlets or written materials about the management of hyperglycemia.