Ms. B., a 74-year-old woman who lives alone, is admitted to the hospital because of weakness and confusion. She has a history of chronic heart and chronic diuretic.

Objective Data
Physical Examination:
• Neurologic: Confusion, slow to respond to questioning, generalized weakness
• Cardiovascular: BP 90/62, HR 112 and irregular, peripheral pulses weak; ECG indicates sinus tachycardia
• Pulmonary: Respirations 12/min and shallow
• Additional findings: Decreased skin turgor; dry mucous membranes

Laboratory Results:
• Serum electrolytes
¦¦ Na+: 141 mEq/L (141 mmol/L)
¦¦ K+: 2.5 mEq/L (2.5 mmol/L)
¦¦ Cl−: 85 mEq/L (85 mmol/L)
¦¦ HCO3 −: 34 mEq/L (34 mmol/L)
• BUN: 42 mg/dL (15 mmol/L)
• Hct: 49%
• Arterial blood gases
¦¦ pH: 7.52
¦¦ PaCO2: 55 mm Hg
¦¦ PaO2: 88 mm Hg
¦¦ HCO3 −: 34 mEq/L (34 mmol/L)

Evaluate P. B.’s fluid volume and electrolyte status. Which physical assessment findings support your analysis? Which laboratory results support your analysis? What is the most likely etiology of these imbalances?