Nursing care
Why Kussmaul breathing occurs in DKA and what a change in pattern means
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated October 2026
Short answer
Kussmaul breathing in DKA is the lungs compensating for metabolic acidosis. Without insulin, the liver turns fatty acids into ketoacids, which lower blood bicarbonate and pH. The brainstem responds by driving deep, rapid breaths that blow off carbon dioxide. Breathing that settles as acidosis clears is expected; breathing that tires or slows while the client is still acidotic is a warning sign.
From missing insulin to ketoacids in the blood
Insulin normally restrains the breakdown of fat. When insulin is absent or far too low, fat cells release free fatty acids and the liver converts them into ketone bodies, mainly acetoacetic acid and beta-hydroxybutyric acid. These are strong organic acids. As they accumulate, they consume bicarbonate, the main buffer in the blood, and the result is a high anion gap metabolic acidosis.
This is why DKA is a problem of acid as well as glucose. A very high glucose explains thirst, polyuria and dehydration, but it does not explain the breathing pattern. The breathing change follows the falling bicarbonate and pH. Keep that link in mind, because it tells you which laboratory trend the respirations should mirror as treatment proceeds.
How the lungs try to correct the pH
Carbon dioxide dissolved in blood behaves as an acid. When chemoreceptors detect a falling pH, the respiratory centre increases ventilation to remove more carbon dioxide, which pushes the pH back toward normal. In DKA this produces long, deep breaths that are often rapid as well, sometimes with a fruity smell from exhaled acetone. Many clients do not report feeling short of breath despite the effort.
On an arterial blood gas, this appears as a low pH, low bicarbonate and a low PaCO2. The low carbon dioxide is compensation, not a separate respiratory problem. Compensation limits the fall in pH but rarely normalises it completely. Clinicians compare the measured PaCO2 with the expected value to judge whether breathing is keeping up or whether a second acid-base disorder is present.
Reading the breathing pattern during treatment
As fluids and insulin stop ketone production and the anion gap closes, the drive to hyperventilate fades. A gradual return to a normal rate and depth, alongside improving bicarbonate and pH, is the expected trend. Document rate, depth, effort, oxygen saturation and level of consciousness together so the pattern can be compared with each set of laboratory results.
Concerning changes are those that do not match the laboratory picture. Slowing, shallow breathing in a client who is still markedly acidotic may mean respiratory muscle fatigue or a falling level of consciousness, and the pH can drop quickly once compensation fails. New headache, irritability or reduced responsiveness during treatment, especially in children, needs urgent escalation because cerebral oedema is a rare but serious complication.
Telling Kussmaul breathing apart from other fast breathing
Tachypnoea has many causes, and not every fast-breathing client with diabetes has DKA. Kussmaul breathing is notable for its depth and regularity rather than for distress. Anxiety, pain, sepsis, pneumonia and pulmonary embolism can all raise the respiratory rate, and some of these can trigger DKA in the first place. The breathing pattern is a clue to be interpreted with glucose, ketones and gas results, not a diagnosis.
Hyperosmolar hyperglycaemic state can produce extreme glucose levels with little or no ketoacidosis, so deep compensatory breathing is less typical there. If a client with very high glucose is breathing normally, the acid-base picture may differ from DKA. Report the full set of findings rather than labelling the condition from one sign, and let the provider interpret the laboratory results.
Worked scenario: easing or exhausted?
Consider a hypothetical adult admitted with DKA who had deep, rapid respirations on arrival. Four hours later the respiratory rate has fallen and the breaths are shallow, the client is drowsy, and the latest gas still shows severe acidosis with no change in bicarbonate. Options include documenting improvement, encouraging rest, increasing the fluid rate, or reporting the change urgently.
Reporting the change is the strongest answer. A slower rate only signals improvement when the acidosis is also improving; here the numbers have not moved and consciousness has worsened, so the slowing suggests failing compensation or neurological deterioration. Encouraging rest misses the risk, and changing an infusion rate without a prescription is outside the nurse's role. Assess airway and consciousness while the provider reviews.
Sources and further reading
Merck Manual Professional: Diabetic ketoacidosis (DKA). Ketoacid production without insulin, Kussmaul respirations, acetone breath and cerebral oedema risk.
Merck Manual Professional: Metabolic acidosis. Respiratory compensation by hyperventilation, expected PaCO2 and high anion gap causes including ketoacidosis.
MedlinePlus: Diabetic ketoacidosis. Deep, rapid breathing and fruity breath as presenting features; insulin and fluid treatment goals.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our endocrine practice questions are the closest set to what this page covers.
Common questions
Is Kussmaul breathing a sign of a lung problem in DKA?
Not usually. It is the respiratory system compensating for metabolic acidosis by removing carbon dioxide. Lung conditions such as pneumonia can still coexist, so assess breath sounds, oxygen saturation and the overall picture.
Why should the PaCO2 be low in DKA?
Deep, rapid breathing removes carbon dioxide, which partly offsets the fall in pH caused by ketoacids. A PaCO2 higher than expected for the degree of acidosis can mean breathing is not keeping up and needs prompt review.
Does Kussmaul breathing stop as soon as glucose falls?
It follows the acidosis rather than the glucose. Glucose often falls before ketones clear, so breathing may stay deep until the anion gap closes and bicarbonate recovers.