A client with septic shock has the following data: pH 7.28, PaCO2 32 mmHg, HCO3 18 mEq/L, and elevated lactate.
Which interpretation best explains the client's condition?
Metabolic alkalosis.
Metabolic acidosis.
Respiratory alkalosis.
Respiratory acidosis.
The Correct Answer is B
Choice A rationale
Metabolic alkalosis is characterized by an elevated pH above 7.45 and an elevated bicarbonate level above 26 mEq/L. It often results from the loss of gastric acid through vomiting or excessive bicarbonate intake. The client in this scenario has a pH of 7.28 and an HCO3 of 18 mEq/L, which are both below the normal ranges of 7.35 to 7.45 and 22 to 26 mEq/L. Therefore, an alkalotic state is clinically impossible.
Choice B rationale
Metabolic acidosis is confirmed by a pH below 7.35 and a bicarbonate level below 22 mEq/L. In septic shock, tissue hypoxia leads to anaerobic metabolism and the production of lactic acid. The accumulation of lactate consumes bicarbonate buffers, causing the HCO3 to drop to 18 mEq/L. The PaCO2 of 32 mmHg reflects partial respiratory compensation, as the lungs attempt to blow off CO2 to raise the pH. The data perfectly matches lactic acidosis pathophysiology.
Choice C rationale
Respiratory alkalosis occurs when the pH is above 7.45 and the PaCO2 is below 35 mmHg, typically due to hyperventilation. While this client has a low PaCO2 of 32 mmHg, their pH of 7.28 indicates acidemia rather than alkalemia. In this context, the low PaCO2 is a compensatory mechanism for the primary metabolic acid-base disturbance rather than the primary cause of the imbalance. The presence of elevated lactate further confirms a primary metabolic origin.
Choice D rationale
Respiratory acidosis is defined by a pH below 7.35 and a PaCO2 above 45 mmHg, usually resulting from alveolar hypoventilation or lung disease. This client has a low PaCO2 of 32 mmHg, which contradicts a respiratory cause for the acidosis. In respiratory acidosis, the kidneys would eventually compensate by retaining bicarbonate, but this client's bicarbonate is low at 18 mEq/L. The clinical picture of sepsis and high lactate strongly points toward metabolic failure.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
Increased protein synthesis is typically an anabolic process that occurs under the influence of growth hormone or testosterone, and it is not a hallmark of hypothyroidism. In a hypothyroid state, there is actually a decrease in both protein synthesis and protein degradation. The lack of thyroid hormone leads to a general slowing of all cellular activities. Weight gain in this condition is not due to the accumulation of muscle mass or protein but rather metabolic slowdown.
Choice B rationale
Thyroid hormones, specifically thyroxine and triiodothyronine, are the primary regulators of the basal metabolic rate, which is the amount of energy the body expends at rest. In hypothyroidism, low levels of these hormones lead to a significant decrease in oxygen consumption and caloric burning by cells. Consequently, even with a normal or reduced caloric intake, the body stores more energy as fat and retains excess water and mucopolysaccharides, leading to the characteristic weight gain.
Choice C rationale
Increased glucose metabolism would typically lead to weight loss or increased energy expenditure, which is seen in hyperthyroidism, not hypothyroidism. In a hypothyroid state, the rate of glucose absorption from the gastrointestinal tract is decreased, and the peripheral uptake of glucose by cells is slowed down. The body's inability to efficiently process and burn glucose as fuel contributes to the overall sluggishness and weight gain associated with the deficiency of circulating thyroid hormones.
Choice D rationale
Thyroid hormones normally increase the sensitivity of cells to catecholamines like epinephrine and norepinephrine by upregulating beta-adrenergic receptors. In hypothyroidism, there is a decreased sensitivity to these catecholamines. This reduction in sympathetic nervous system responsiveness leads to a slower heart rate and decreased lipolysis, which is the breakdown of fats. The inability to effectively mobilize fat stores for energy due to this decreased sensitivity contributes directly to the accumulation of adipose tissue.
Correct Answer is ["A","C","E"]
Explanation
Choice A rationale
Hyponatremia occurs in SIADH due to the excessive secretion of antidiuretic hormone, which causes the kidneys to reabsorb an inappropriate amount of free water. This water retention dilutes the concentration of sodium in the extracellular fluid, leading to serum sodium levels falling below the normal range of 135 to 145 mEq/L. The resulting dilutional hyponatremia can lead to cellular edema and significant neurological complications if the water intake is not strictly restricted to manage the imbalance.
Choice B rationale
Hypernatremia is not associated with SIADH because the primary pathophysiology involves water retention rather than water loss or sodium excess. Hypernatremia, defined as a serum sodium level greater than 145 mEq/L, is typically seen in conditions like diabetes insipidus where there is a deficiency of antidiuretic hormone or a lack of renal response to it. In SIADH, the body retains too much water, which consistently lowers the sodium concentration through dilution rather than raising it through dehydration.
Choice C rationale
Concentrated urine is a hallmark of SIADH because the high levels of circulating antidiuretic hormone act on the renal collecting ducts to increase water permeability. This results in maximum water reabsorption back into the systemic circulation, leaving very little water to be excreted. Consequently, the urine produced is highly concentrated with a high specific gravity, typically exceeding 1.030, and a high urine osmolality, reflecting the body's inability to excrete excess water despite low serum osmolality levels.
Choice D rationale
Polyuria is the excretion of large volumes of dilute urine, which is the opposite of what occurs in SIADH. Patients with SIADH actually experience oliguria because the kidneys are reabsorbing almost all filtered water under the influence of excessive antidiuretic hormone. Polyuria is a clinical manifestation of diabetes insipidus or osmotic diuresis, where the kidneys fail to concentrate urine. In SIADH, the volume of urine output is significantly decreased while the concentration of the urine remains abnormally high.
Choice E rationale
Low serum osmolality is a direct result of the excessive water retention seen in SIADH. As the body reabsorbs free water in the distal tubules and collecting ducts, the blood becomes diluted, lowering the concentration of particles. Normal serum osmolality ranges from 275 to 295 mOsm/kg. In SIADH, this value drops below 275 mOsm/kg. This hypoosmolar state occurs simultaneously with the production of concentrated urine, which is a diagnostic indicator that the ADH secretion is inappropriate.
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