Page 439 - Clinical Application of Mechanical Ventilation

Management of Mechanical Ventilation 405

Oral intake of potassium replacement is safer. If an intravenous route is used,
Oral intake of potassium there are four precautions that must be followed to ensure patient safety (Eggleston,
replacement is safer. If an
intravenous route is used, 1985): (1) Consider replacement only if the urine output is at least 40 to 50 mL/
precautions must be followed
to ensure patient safety. hour; (2) Never use KCl undiluted as it can cause arrhythmias and cardiac arrest;
(3) Do not give more than 40 mEq of potassium in any one hour or more than
200 mEq in 24 hours; and (4) Concentration of potassium in the intravenous drip
should not be higher than 40 mEq/L.

Hyperkalemia. Hyperkalemia is an uncommon condition in the clinical setting,
but when hyperkalemia occurs it is usually due to renal failure. Decrease in urine
Hyperkalemia is usually output (less than 200 to 300 mL/day) secondary to renal failure leads to retention
caused by renal failure.
of potassium ions. Therefore, the primary treatment for this form of hyperkalemia
is to improve kidney function.
In acute hyperkalemia, intravenous (IV) calcium chloride or calcium gluconate
may aid in antagonizing the cardiac toxicity provided that the patient is not re-
ceiving digitalis therapy. Cellular uptake of potassium (from extracelluar com-
partment) may be increased by using sodium bicarbonate IV, regular insulin, and
glucose IV. Beta-adrenergic (e.g., albuterol) shows various results. Elimination of
total body potassium may be enhanced by using sodium polystyrene sulfonate
(Kayexalate) orally (PO)/rectally (PR), furosemide (with normal renal function).
Emergency hemodialysis is the treatment for life threatening hyperkalemia (Verive
et al., 2010).

NUTRITION

Nutritional intake should be adjusted according to a patient’s requirements. Inad-
equate intake may lead to impaired respiratory function due to reduction in the
efficiency of respiratory muscles. Excessive intake may increase the patient’s work
of breathing due to the increased metabolic rate and carbon dioxide production.

Undernutrition

Proper nutritional support is a therapeutic necessity for patients on a mechani-
Inadequate nutritional cal ventilator. Poor nutritional status may lead to rapid depletion of cellular
support can lead to fatigue of
respiratory muscles. stores of glycogen and protein in the diaphragm (Mlynarek et al., 1987). It also
leads to fatigue of the major respiratory muscles in patients with or without
lung diseases and contributes to impaired pulmonary function, hypercapnia,
and inability to wean (Fiaccadori & Borghetti, 1991). Risk of infection becomes
more likely when a patient is undernourished because of resultant decreased
cell-mediated immunity. Interstitial and pulmonary edema may develop because
of severe hypoalbuminemia in which the osmotic pressure is decreased and the
fluid is shifted into the interstitial space (interstitial edema), and eventually into
the alveoli (pulmonary edema). Other complications of undernutrition include
poor wound healing and decreased surfactant production (Table 12-17) (Ideno
et al., 1995).

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