Nursing care
Respiratory Alkalosis nursing care: what to assess and what to do first
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
Respiratory alkalosis is a primary fall in PaCO2 from alveolar hyperventilation, most often driven by anxiety, pain, fever, or hypoxia. The nurse's first job is finding and treating the cause, not the paper bag. ABGs show pH above 7.45 with PaCO2 below 35 mmHg. Left untreated, it can progress to tetany and seizures from falling ionised calcium.
The clinical picture
Respiratory alkalosis develops when a patient blows off carbon dioxide faster than the body produces it. The trigger is almost always something driving the respiratory rate up: acute anxiety or a panic attack, uncontrolled pain, fever, early sepsis, salicylate toxicity, pregnancy, or hypoxia from pulmonary embolism or asthma. The mechanism is alveolar hyperventilation, and the ABG signature is a pH above 7.45 with a PaCO2 below 35 mmHg.
The patient rarely presents with a diagnosis already written on the chart. They present tachypnoeic, often frightened, sometimes reporting that their hands are tingling or their lips feel numb. Circumoral and peripheral paraesthesia comes from the drop in ionised calcium that follows a rising pH, not from the CO2 shift itself. Recognising that link is what separates a nurse who treats the numbers from one who treats the patient in front of them.
Assessment: what to look for and in what order
Start with the respiratory rate and pattern before anything else. Count it for a full minute if the patient is anxious, because a rushed count under-reads a genuinely elevated rate. Ask directly what preceded the episode: new pain, a panic trigger, a fever spike, recent opioid administration reversed too aggressively, or a known anxiety disorder. The history usually names the cause faster than any lab value.
Move to neuromuscular signs next, since these track the falling ionised calcium and tell you how far the patient has progressed. Check for circumoral numbness, paraesthesia in the fingers, and carpal spasm. A positive Trousseau's sign, carpal spasm on inflating a blood pressure cuff, or a positive Chvostek's sign, facial twitching on tapping the facial nerve, both confirm hypocalcaemia-driven irritability and should prompt escalation rather than reassurance alone.
Pull the ABG once it is available and confirm the pattern: pH up, PaCO2 down, bicarbonate normal in an acute picture or beginning to fall in a compensating chronic one. Correlate the ABG with SpO2 and the underlying diagnosis, because hyperventilation secondary to hypoxia needs oxygen, not calming words.
Immediate interventions
Paper-bag rebreathing has fallen out of practice and should not be taught or used as a default response. It can mask a hypoxic driver of hyperventilation and has caused documented harm when the underlying cause was pulmonary embolism or asthma rather than anxiety. The current standard is to identify and treat the trigger directly.
If pain is driving the rate, administer the prescribed analgesic and reassess the respiratory rate within the expected onset window rather than waiting for the next scheduled round. If anxiety is the driver, stay with the patient, coach slow diaphragmatic breathing at a set pace, and reduce environmental stimulation before reaching for an anxiolytic. If hypoxia is suspected, apply supplemental oxygen and pull pulse oximetry and an ABG before assuming a psychological cause.
Reassess the respiratory rate and neuromuscular signs after each intervention. A patient whose tingling resolves as the rate slows is responding appropriately; one whose carpal spasm persists or worsens needs escalation, because ongoing hypocalcaemia-driven tetany can progress to laryngospasm.
Ongoing nursing management
Once the acute picture is controlled, shift to identifying and managing the underlying condition so the episode does not repeat. A patient hyperventilating from uncontrolled pain needs a review of the analgesic regimen, not just a single dose. One with an anxiety disorder benefits from a referral for ongoing coping strategies alongside any as-needed medication.
Monitor serial ABGs or venous CO2 if the patient is at risk of recurrence, and trend the respiratory rate on the observation chart rather than relying on a single spot check. Document the trigger identified and the intervention given, since this record is what tells the next nurse on shift what to expect and what worked.
Patient and family education
Explain the episode in terms the patient can act on: fast breathing lowers carbon dioxide in the blood, and that shift is what caused the tingling and lightheadedness, not a heart problem or a stroke. Naming the mechanism reduces the fear that often perpetuates the hyperventilation cycle.
Teach paced breathing, in for a count of four, out for a count of six, as a tool the patient can use before the next trigger builds. If anxiety is a recurring driver, discuss it openly and connect the patient with outpatient support rather than treating each episode in isolation. Advise the family not to offer a paper bag at home for the same reason the nurse does not use one on the ward: it can hide a serious cause behind an apparently calming ritual.
How this appears on the NCLEX
Expect a scenario item describing an anxious or postoperative patient with a rapid respiratory rate, perioral numbness, and tingling fingers, then asking for the priority nursing action. The correct answer addresses the underlying cause, treating pain, applying oxygen, or coaching breathing, rather than selecting a rebreathing device as a distractor option.
Lab-based items will give an ABG with pH above 7.45 and PaCO2 below 35 mmHg and ask you to classify it as respiratory alkalosis before asking about compensation. Know that the kidneys compensate slowly, over one to three days, by excreting bicarbonate, so an acute ABG will show a normal bicarbonate even though the pH is already abnormal.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our respiratory practice questions are the closest set to what this page covers.
Common questions
Why is rebreathing into a paper bag no longer recommended for respiratory alkalosis?
It can mask a hypoxic cause such as pulmonary embolism or asthma, since the patient's oxygen saturation is not addressed while they breathe recycled air. Current practice treats the underlying trigger, pain, anxiety, fever, or hypoxia, directly instead.
What causes the tingling and numbness in respiratory alkalosis?
A rising pH shifts calcium binding to plasma proteins, lowering ionised calcium even though total serum calcium stays normal. That drop in ionised calcium increases neuromuscular excitability, producing perioral numbness, finger paraesthesia, and in severe cases carpal spasm.
How do you tell respiratory alkalosis from metabolic alkalosis on an ABG?
Respiratory alkalosis shows a primary drop in PaCO2 below 35 mmHg with an elevated pH; metabolic alkalosis shows a primary rise in bicarbonate above 26 mEq/L with an elevated pH. Checking which value moved first, and whether the other is compensating, tells you which system started the imbalance.
Is respiratory alkalosis always caused by anxiety?
No. Anxiety and pain are common triggers, but hypoxia, fever, sepsis, salicylate toxicity, and pregnancy all cause hyperventilation through the same mechanism. Ruling out a physiological cause before attributing the episode to anxiety is a safety step, not an optional extra.