The patient presents with shortness of breath, inability to fill their lungs, palpitations, chest or abdominal pain, and tingling or numbness. Their respiratory rate is increased with a larger tidal volume or frequent sighing. The physical exam is otherwise normal. The patient's history may reveal an emotional trigger for the hyperventilation. The doctor should perform a brief physical exam, check pulse oximetry, explain the hyperventilation cycle and have the patient slow their breathing, use a paper bag or tubing for the patient to rebreathe exhaled air if needed to increase carbon dioxide levels and calm breathing, and consider administering hydroxyzine. If symptoms are not reversed within 15-20 minutes

1. Hyperventilation
Presentation
The patient is anxious and complains of shortness of breath and an
inability to fill the lungs adequately. A patient may also have palpitations,
chest or abdominal pain, and tingling or numbness around the mouth and
fingers, or possibly even flexor spasm of the hands and feet. His respiratory
volume is increased, which may be apparent by an increased respiratory rate,
or only be an increased tidal volume or frequent sighing. The remainder of
the physical examination is normal. The patient's history may reveal an
obvious precipitating emotional cause (such as having been caught stealing or
being in the midst of a family quarrel).
What to do:
• Perform a brief physical examination, checking especially that the
patient's mental status is good, there is no unusual breath odor, there
are good, equal excursion and breath sounds in both sides of the
chest, and there is no swelling, pain or inflammation of the legs.
• Measure pulse oximetry, which should be 98-100%.
• Explain to the patient the cycle in which rapid, deep breathing can
cause physical symptoms upsetting enough to cause further rapid,
deep breathing. Repeat a cadence ("in...out...in...") to help him
voluntarily slow his breathing, or have him voluntarily hold his breath
for a while.
• If he cannot reduce his ventilatory rate and volume, provide a paper
bag or length of tubing through which to breathe, keeping the pulse
oximetry monitor on to avoid hypoxia. This will allow him to continue
moving a large quantity of air, but provide air rich in carbon dioxide,
allowing the blood Pco2 to rise towards normal. (Carbogen gas (5%
CO2) may also be used, if available.) Administration of 50-100mg of
hydroxyzine (Vistaril) im often helps to calm the patient.
• If you cannot reverse these symptoms and reduce respiratory effect in
this manner in 15-20 minutes, you should double check the diagnosis
by obtaining arterial blood gases, looking for a metabolic acidosis or
hypoxia indicative of underlying disease.
• Reexamine the patient after hyperventilation is controlled.
• Make sure the patient understands the hyperventilation syndrome and
knows some strategies for breaking the cycle next time. (It may be
valuable to have him reproduce the symptoms voluntarily.) Arrange for
followup as needed.
What not to do:

2. • Do not miss the true medical emergencies which also present as
hyperventilation, including: pneumothorax, pneumonia, pulmonary
embolus, diabetic ketoacidosis, salicylate overdose, sepsis, uremia,
myocardial infarction and CVA.
• Do not use a paper bag on a patient with a low oxygen saturation on
pulse oximetry (<96%)
Discussion
The acute metabolic alkalosis of hyperventilation causes transient imbalances
of calcium, potassium, and perhaps other ions, with the net effect of
increasing the irritability and spontaneous depolarization of excitable muscles
and nerves. First-time victims of the hyperventilation syndrome are the most
apt to visit the ED, and this is an excellent time to educate them about its
pathophysiology and the prevention of recurrence. Repeat visitors may be
overly excitable or may have emotional problems and need counseling.