A client has been classified as asthmaticus. The nurse understands that this client will likely initially exhibit symptoms of:

Status asthmaticus is a severe, prolonged asthma attack that does not respond to standard bronchodilator therapy. In the early phase of this condition, the client hyperventilates in an effort to overcome airway obstruction and hypoxia. This increased respiratory rate causes excessive elimination of carbon dioxide (CO2), driving the PaCO2 below normal and raising the blood pH above 7.45 — the hallmark of respiratory alkalosis. The nurse should therefore expect initial arterial blood gas results showing a low PaCO2 with an elevated pH. As the attack progresses and the client fatigues, the respiratory muscles can no longer sustain hyperventilation, CO2 begins to accumulate, and the condition shifts to respiratory acidosis — a sign of impending respiratory failure and a medical emergency. Metabolic alkalosis would result from loss of acid or gain of bicarbonate through non-respiratory mechanisms, which is not the primary pathophysiology here. Metabolic acidosis may occur later in severe cases due to lactic acidosis from respiratory muscle fatigue, but it is not the initial presentation. Recognizing early respiratory alkalosis as the first acid-base disturbance in status asthmaticus is critical for timely intervention and monitoring for deterioration.