In reviewing the electrolytes of a patient, the nurse notes the serum potassium level has increased from 4.3 mEq/L to 5.9 mEq/L. Which assessment does the nurse initiate first to prevent further harm?

Antihistamines primarily work by blocking the H1 receptors, which are the receptors responsible for mediating the actions of histamine in the body. By blocking these receptors, antihistamines prevent or reduce the effects of histamine, such as itching, sneezing, runny nose, and watery eyes. This is the main mechanism by which antihistamines provide their therapeutic effects. "Antihistamines block release of histamine from mast cells and basophils." This statement is incorrect. Antihistamines do not block the release of histamine; instead, they block the histamine receptors to prevent the effects of histamine.

"H1 antagonists can bind to H1 receptors, H2 receptors, and muscarinic receptors." This statement is incorrect. H1 antagonists, or H1 receptor blockers, specifically bind to H1 receptors and do not have significant affinity for H2 receptors or muscarinic receptors. "First-generation antihistamines are more selective than second-generation antihistamines." This statement is incorrect. First-generation antihistamines are generally less selective and can have more sedating and anticholinergic effects compared to second-generation antihistamines, which are designed to be more selective for H1 receptors and have reduced sedative properties.

The pH value of 7.5 indicates alkalosis, as it is above the normal range of 7.35-7.45. The elevated bicarbonate (HCO3-) level of 34 mmol/L suggests metabolic alkalosis, as it is higher than the normal range of 22-28 mmol/L. The PaCO2 level of 40 mm Hg falls within the normal range of 35-45 mm Hg.

In this case, the primary disturbance is metabolic alkalosis, which is likely caused by vomiting leading to excessive loss of gastric acid (hydrogen ions) and chloride ions from the stomach. This loss of acid and chloride results in an imbalance of electrolytes and an increase in bicarbonate levels, leading to metabolic alkalosis.

The arterial blood gas results do not indicate any compensation. Compensation occurs when the body attempts to restore the pH balance by adjusting the respiratory or metabolic systems. In this case, there is no compensation observed because the PaCO2 level is within the normal range and not significantly altered.