Hyperventilation

Hyperventilation
ICD-10	R06.4
ICD-9	786.01

Tachypnea
ICD-10	R06.0
ICD-9	786.06

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1],Associate Editor(s)-in-Chief: Jyostna Chouturi, M.B.B.S [2]

Overview

In medicine, hyperventilation (or overbreathing) is the state of breathing faster and/or deeper than necessary, thereby reducing the carbon dioxide concentration of the blood below normal..Stress or anxiety commonly are causes of hyperventilation; this is known as hyperventilation syndrome. Hyperventilation can also be brought about voluntarily, by taking many deep breaths.

This is in contrast to hyperpnea, where the increased breathing is required to meet demand, as during and following exercise or when the body lacks oxygen (hypoxia), for instance in high altitude or as a result of anaemia. Hyperpnea may also occur as a result of sepsis, and is usually a sign of the beginning of refractory sepsis.

Hyperventilation can, but does not necessarily cause symptoms such as numbness or tingling in the hands, feet and lips, lightheadedness, dizziness, headache, chest pain, slurred speech and sometimes fainting, particularly when accompanied by the Valsalva maneuver. Sometimes hyperventilation is induced for these same effects. Hyperventilation can sometimes be self induced for moments of needed focus and adrenaline.

The related symptom tachypnea (or "tachypnoea") (Greek: "rapid breathing") is characterized by rapid breathing and is not identical with hyperventilation - tachypnea may be necessary for a sufficient gas-exchange of the body, for example after exercise, in which case it is not hyperventilation.

Lastly, in the case of metabolic acidosis, the body uses hyperventilation to counter the increased acidity of the blood; this is known as Kussmaul breathing.

Causes

Life-Threatening Causes

• Diabetic ketoacidosis
• Heat stroke
• Pulmonary embolism
• Respiratory alkalosis
• Sepsis

Common Causes

• Acute altitude sickness
• Anxiety
• Ascites
• Asthma
• Chronic obstructive pulmonary disease
• Congestive heart failure
• Drugs- Amphetamine, Aspirin
• Encephalitis
• Exercise
• Fever
• Graves' disease and
• Head injury
• Hyperthyroidism
• Meningitis
• Panic disorder
• Pneumonia
• Pneumothorax
• Pregnancy
• Pulmonary edema
• Pulmonary embolus
• Pulmonary fibrosis
• Stress
• Stroke

Causes by Organ System

Cardiovascular	Cheyne-stokes respirations, congestive cardiac failure,pulmonary embolism, stroke
Chemical/Poisoning	Ammonium chloride ,camphor ,glycol ether ,inhalation of irritants,methanol ,Salicylate poisoning,
Dental	No underlying causes
Dermatologic	No underlying causes
Drug Side Effect	Aminophylline, aspirin, coffee abuse, pralidoxime, tiagabine
Ear Nose Throat	No underlying causes
Endocrine	Diabetic ketoacidosis, renal disease
Environmental	Acute stress disorder
Gastroenterologic	Abdominal surgery, acute liver failure, acute porphyria, end stage liver failure , hepatic cirrhosis, intestinal fistula, pyloric stenosis
Genetic	Acute porphyria, arginosuccinic aciduria, carbamoylphosphate synthetase 1 deficiency disease, carbonic anhydrase va deficiency, hereditary fructose-1,6-bisphosphatase deficiency, Pitt-hopkins syndrome
Hematologic	Acute porphyria
Iatrogenic	No underlying causes
Infectious Disease	CNS infection, fever
Musculoskeletal/Orthopedic	Hip cancer
Neurologic	Altitude sickness, acute, brain trauma, central neurogenic hyperventilation, cerebrovascular accident, CNS infection, cree leukoencephalopathy , damaged respiratory pathways, epilepsy, epileptic encephalopathy, early infantile, 2, head injury, intracranial space-occupying lesion, meningoencephalitis, pain, Pitt-hopkins syndrome, raised intracranial pressure, stroke, Vasovagal attacks
Nutritional/Metabolic	Diabetic ketoacidosis, hereditary fructose-1,6-bisphosphatase deficiency, heat stroke, lactic acidosis
Obstetric/Gynecologic	No underlying causes
Oncologic	Bronchial neoplasm, rib tumor
Ophthalmologic	No underlying causes
Overdose/Toxicity	Biguanide intolerance
Psychiatric	Acute stress disorder , adult panic-anxiety syndrome, agoraphobia, anxiety , Briquet's syndrome, combat stress reaction , cree leukoencephalopathy , crying or severe distress, Da costa syndrome, depression, distress, excitement, fear, functional disorders, grief, hypochondriasis, hysteria, malingering, pain, panic attack , phobia, primary habit disorder, Rett's syndrome, schizophrenia, stress, strong emotions
Pulmonary	Acute altitude sickness, apneustic respirations, asthma, ataxic respiration, biot's respiration, central neurogenic hyperventilation, Cheyne-stokes respirations, damaged respiratory pathways, diffuse pulmonary fibrosis, emphysema , hyperventilation syndrome, inhalation of irritants, lung damage, metabolic acidosis , persistent hypoxemia, pleural effusion, pneumonia, pneumothorax, pulmonary embolism, pulmonary oedema
Renal/Electrolyte	Acid-base imbalance , metabolic acidosis , phaeochromocytoma, renal disease
Rheumatology/Immunology/Allergy	Asthma, pseudoallergic reactions
Sexual	No underlying causes
Trauma	Brain trauma, head injury, lung damage, raised intracranial pressure, sponatneous pneumothorax, stroke, surgical relocation of ureters in ileum or colon
Urologic	Surgical relocation of ureters in ileum or colon
Miscellaneous	Abdominal surgery, adulation, childbirth, fever

Causes in Alphabetical Order

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Mechanism

In normal breathing, both the depth and frequency of breaths is varied by the neural system primarily in order to maintain normal amounts of carbon dioxide but also to supply appropriate levels of oxygen to the body's tissues. This is mainly done by measuring the carbon dioxide content of the blood; normally, a high carbon dioxide concentration signals a low oxygen concentration, as we breathe in oxygen and breathe out carbon dioxide at the same time, and the body's cells use oxygen to burn fuel molecules to carbon dioxide.

The gases in the alveoli of the lungs are nearly in equilibrium with the gases in the blood. Normally, less than 10% of the gas in the alveoli is replaced each breath. Deeper or quicker breaths exchange more of the alveolar gas with air and have the net effect of drawing more carbon dioxide out of the body, since the carbon dioxide concentration in normal air is very low.

The resulting low concentration of carbon dioxide in the blood is known as hypocapnia. Since carbon dioxide is held in the blood mostly in the form of carbonic acid, hypocapnia results in the blood becoming alkaline, i.e. the blood pH value rises. (In the normal person, this alkalosis would automatically be countered by reduced breathing, but for various reasons this doesn't happen when the neural control is not present.)

If carbon dioxide levels are high, the body assumes that oxygen levels are low, and accordingly the brain's blood vessels dilate, to assure sufficient blood flow and supply of oxygen. Conversely, low carbon dioxide levels (e.g. from hyperventilation) cause the brain's blood vessels to constrict, resulting in reduced blood flow to the brain and lightheadedness. Thus, though it seems counterintuitive, breathing too much can result in a decrease in the oxygen supply to the brain. Doctors sometimes artificially induce hyperventilation after head injury to reduce the pressure in the skull, though the treatment has potential risks.

The high pH value resulting from hyperventilation also reduces the level of available calcium (hypocalcemia), which affects the nerves and causes the numbness or tingling of the hands. This occurs because alkalinisation of the plasma proteins (mainly albumin) increases their calcium affinity.

Differentiating hyperventilation from other diseases:

Organ system	Diseases	Clinical manifestations									Diagnosis					Other features
		Symptoms				Physical exam
		Chest pain	Dyspnea	Fever	Palpitations	Cyanosis	Tachypnea	JVD	Peripheral edema	Auscultation	ABGs	Lab findings	Imaging	PFT	Gold standard
Pulmonary system	Pneumothorax	+	+	+	+	+	+	_	_	Decreased breath sounds			X- ray - Mediastinal shift Deep sulcus sign Hydropneumothorax CT-scan- Bullae		CT-scan	Hypoxia, Hypercapnia Hyperesonance to percussion, Vocal resonance Tactile fremitus decreased
	Pulmonary embolism	+	+	+	+	+	+
	Pneumonia	+	+	+	+	+	+	-	-	Bronchial breath sounds Crepitations Bronchophony Egophony Whispering pectoroloqy		CBC Blood culture Mantoux test Serology (mycoplasma, viruses) Sputum: Gram stain and culture	CXR- Lobar consolidation, Air bronchogram; Atypical pneumonia: Diffuse interstitial infiltrates
	Exacerbation of asthma/COPD	-	+	-	+	+	+	-	-	Decreased breath sounds Wheezing Coarse crackles	Increased PaCo2 Decreased PaO2	CBC- Increased hematocrit from chronic hypoxia Sputum evaluation, BNP( to rule out heart failure)	X- ray: Hyperinflated lungs Flattening of the diaphragm Narrow heart shadow Cardiomegaly	Increased TLC Increased RV Decreased Vital capacity Decreased DLco ( Emphysema) Normal DLco ( Chronic bronchitis)	HRCT ( High resolution computed tomography of the lung)	Productive cough Exercise intolerance Altered mental status Cor-pulmonale Hyperresonance on percussion
	Interstitial lung disease	+	+	-/+	+	+	+	-/+	-	Fine crackles Loud P2	Increased A-a gradient Decreased PaO2 Increased PaCo2		Chest X-ray- Reticular infiltrates Honey combing	FEV1 decreased FVC decreased TLC decreased RV decreased DLco decreased FEV1/FVC normal	HRCT -more accurate than chest xray Most accurate test is lung biopsy	Physical examination shows clubbing Decreased pulmonary compliance
	Intrapulmonary shunt
	Upper airway obstruction	-/+	+	-	-/+	-/+	+	-/+	-	Inspiratory stridor	Increased PaCo2 Decreased PaO2		Plain radiograph of the neck Steeple sign (Croup in pediatric population) CT MRI	Decreased vital capacity	HRCT Bronchoscopy	Hoarseness Accessory muscle use during respiration Chest retractions
	High altitude sickness	-	+	+/-	+	+/-	+	-	+	Crackles	Respiratory alkalosis	CBC EKG- Right sided heart strain	CXR- Bilateral patchy infiltrates Brain Ct scan
Cardiovascular system	Acute coronary syndrome	+	+	-	+/-	+/-	+/-	+/-	+/-	S3 Systolic murmur Rales		Cardiac enzymes EKG CBC BNP	Chest radiograph: Cardiomegaly Pulmonary edema Echo cardiography Myocardial perfusion imaging Cardiac angiography
	Heart failure
	Dysrhythmias
	Shock
Metabolic/Systemic disorders	Diabetic ketoacidosis
	Hypocalcemia
	Hypoglycemia
Endocrine system	Hyperthyroidism
	Pheochromocytoma
CNS	Central nervous system tumor
	Anxiety/panic attacks
Others	Pregnancy
	Hepatic failure
	Sepsis

See also

• Hypoventilation, too shallow or too slow breathing
• Control of respiration
• Respiratory alkalosis
• Shallow water blackout, the role of hyperventilation in some drowning incidents