Ricky's grandmother has been suffering from persistent vomiting for two days now.
She appears to be lethargic and weak and has myalgia.
She is noted to have dry mucus membranes and her capillary refill takes >4 seconds.
She is diagnosed as having gastroenteritis and dehydration.
Measurement of arterial blood gas shows pH 7.5, Pa 85 mm Hg, PaCO2 40 mm Hg, and HCO3 34 mmol/VL. What acid-base disorder is shown?
Metabolic Acidosis, with Partial Compensation.
Respiratory Acidosis, with Partial Compensation.
Respiratory Alkalosis, Uncompensated.
Metabolic Alkalosis, Uncompensated.
The Correct Answer is D
Choice A rationale
Metabolic acidosis is characterized by a primary reduction in serum bicarbonate, typically below 22 mmol/L, which drives the pH below the normal range of 7.35. While compensation mechanisms would involve a decrease in PaCO2, the provided arterial blood gas values demonstrate an elevated pH and elevated bicarbonate, which are inconsistent with metabolic acidosis.
Choice B rationale
Respiratory acidosis is primarily defined by an increase in arterial carbon dioxide (PaCO2), above the normal range of 45 mm Hg, leading to a decrease in blood pH below 7.35. Compensation would involve an increase in bicarbonate. The given values, particularly the elevated pH and normal PaCO2, do not align with the characteristics of respiratory acidosis.
Choice C rationale
Respiratory alkalosis is characterized by a primary decrease in PaCO2, below the normal range of 35 mm Hg, leading to an elevated pH above 7.45. Uncompensated means the bicarbonate level remains within the normal range of 22-26 mmol/L. The provided PaCO2 is within normal limits, and bicarbonate is elevated, which contradicts the criteria for respiratory alkalosis.
Choice D rationale
Metabolic alkalosis is characterized by a primary increase in serum bicarbonate (HCO3), typically above the normal range of 26 mmol/L, which results in an elevated blood pH above 7.45. Uncompensated metabolic alkalosis indicates that the PaCO2 remains within its normal range (35-45 mm Hg) as the respiratory system has not yet initiated or completed compensatory hypoventilation. The provided pH of 7.5, PaCO2 of 40 mm Hg, and HCO3 of 34 mmol/L precisely fit this definition.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
While establishing IV access and fluid replacement are crucial in trauma, they are secondary to ensuring cervical spine stabilization in a patient who is unresponsive after a head-on motor vehicle crash. Uncontrolled movement of an unstable cervical spine can lead to irreversible spinal cord injury, exacerbating neurological deficits or causing paralysis.
Choice B rationale
Monitoring pulse and blood pressure frequently is an important ongoing assessment in a trauma patient to identify shock or other systemic issues. However, in the immediate post-crash scenario with an unresponsive patient, the primary concern is preventing further neurological damage from potential spinal cord injury, making stabilization a higher priority.
Choice C rationale
Inserting a nasogastric tube for decompression might be necessary later in the management of a trauma patient to prevent aspiration or gastric distension. However, it is not the immediate priority action in an unresponsive patient following a head-on collision, where airway, breathing, circulation, and most importantly, cervical spine protection are paramount.
Choice D rationale
In an unresponsive client following a head-on motor vehicle crash, cervical spine injury must be presumed until ruled out. Any movement of the head or neck could further compromise the spinal cord, leading to permanent neurological deficits or even death. Therefore, keeping the neck stabilized using a cervical collar and backboard is the absolute priority to prevent further injury.
Correct Answer is ["B","D"]
Explanation
Choice A rationale
A panic attack typically leads to hyperventilation, causing excessive exhalation of carbon dioxide. This results in respiratory alkalosis, characterized by a decreased partial pressure of carbon dioxide (PaCO2) and an elevated pH, due to the rapid elimination of carbonic acid from the body.
Choice B rationale
Morphine overdose depresses the central nervous system, significantly reducing the respiratory drive. This leads to hypoventilation, which causes an accumulation of carbon dioxide (CO2) in the blood. The increased CO2 forms carbonic acid, lowering the blood pH and resulting in respiratory acidosis.
Choice C rationale
Alcohol intoxication primarily affects the central nervous system, leading to respiratory depression similar to opioid overdose. However, severe alcohol intoxication can also cause metabolic acidosis due to lactic acid accumulation from impaired tissue perfusion and metabolism.
Choice D rationale
Sleep apnea causes recurrent episodes of hypoventilation and apnea during sleep. These episodes lead to periods of elevated carbon dioxide (CO2) levels in the blood due to inadequate gas exchange, resulting in intermittent or chronic respiratory acidosis depending on the severity and duration.
Choice E rationale
Cocaine is a stimulant that typically increases respiratory rate and depth. This hyperventilation leads to increased exhalation of carbon dioxide (CO2), resulting in a decrease in PaCO2 and an elevation in blood pH, which is characteristic of respiratory alkalosis.
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