Hyperventilation syndrome

Dr. safeyya alchalabi

Hyperventilation syndrome

Hyperventilation syndrome

Essence
Ventilation exceeds metabolic demands, leading to haemodynamic and chemical changes producing characteristic symptoms (dyspnoea, agitation, dizziness, atypical chest pain, tachypnoea, hyperpnoea, paraesthesiae, and carpopedal spasm) usually in a young, otherwise healthy, patient.

Hyperventilation syndrome

Essence
Hyperventilation syndrome (HVS), a relatively common presentation; may be mistaken for panic disorder.
Considerable overlap, hence inclusion here:
It 50–60% of patients with panic disorder or agoraphobia have symptoms of HVS.
25–35% of HVS patients have symptoms of panic disorder.
may also be confused with other organic diseases, particularly of the cardiorespiratory system, due to the physical symptoms manifest.

Hyperventilation syndrome

Aetiology
Unknown, but certain stressors provoke an exaggerated respiratory response in some individuals e.g. 
emotional distress,
Sodium lactate,
caffeine,
isoprenaline,
cholecystokinin,
carbon dioxide (CO2).


Hyperventilation syndrome
Aetiology
HVS patients tend to use accessory muscles to breathe, rather than the diaphragm, resulting in hyperinflated lungs and perceived effort or dyspnoea when stressors induce the need to take a deep breath. This leads to anxiety and triggers further deep breathing, setting up a vicious cycle.

Hyperventilation syndrome

Epidemiology
♂:♀ = 1:7,
usually presents between 15 and 55yrs but can occur at any age (except infancy).

Hyperventilation syndrome

Symptoms and signs
Cardiac: chest pain/angina atypical of cardiac origin:
may last hours, not minutes;
often relieved by exercise;
glyceryl trinitrate (GTN) ineffective,
ECG changes (prolonged QT, ST depression or elevation, and T-wave inversion).

Hyperventilation syndrome

Symptoms and signs
Respiratory:
hyperpnoea,
tachypnoea,
dyspnoea,
wheeze [bronchospasm secondary to low partial pressure of carbon dioxide in arterial blood (PaCO2)].
Note: in chronic forms, hyperventilation may not be clinically apparent.


Hyperventilation syndrome
Symptoms and signs

CNS [due to reduced cerebral blood flow (CBF) secondary to hypocapnia):

dizziness,
weakness,
confusion,
agitation,
depersonalization,
visual hallucinations,
syncope or seizure (rare),
paraesthesiae (usually upper limbs and bilateral),
peri-oral numbness.

Hyperventilation syndrome

Symptoms and signs
GI:
bloating,
belching,
flatus,
epigastric pressure (due to aerophagia),
dry mouth (due to mouth breathing and anxiety).


Hyperventilation syndrome
Symptoms and signs
Metabolic (due to electrolyte disturbance secondary to respiratory alkalosis):
acute hypocalcaemia (signs: carpopedal spasm, muscle twitching, +ve Chvostek and Trousseau signs, and prolonged QT interval),
hypokalaemia (with generalized weakness),
acute hypophosphataemia (may contribute to paraesthesiae and generalized weakness).

Hyperventilation syndrome

Differential diagnosis
Extensive. Diagnosis of exclusion—
acute respiratory distress syndrome (ARDS),
(venous) air embolism,
asthma,
atrial fibrillation (AF),
atrial flutter,
cardiomyopathy,
chronic obstructive pulmonary disease (COPD),
costochondritis,
diabetic ketoacidosis (DKA),
hyperthyroidism,
metabolic acidosis,
methaemoglobinaemia,

Hyperventilation syndrome

Differential diagnosis
Extensive. Diagnosis of exclusion—
MI,
nasopharyngeal stenosis,
panic (and other anxiety) disorder,
Pleural effusion,
pneumonia,
pneumothorax,
pulmonary embolism (PE),
smoke inhalation,
CO poisoning,
withdrawal syndromes.

Hyperventilation syndrome

Investigations
Unless there is a clear history of HVS, any first presentations of hyperventilation should be referred for exclusion of serious underlying medical problems.

Hyperventilation syndrome

Investigations
These investigations may include full physical,
FBC,
U&Es,
TFTs,
glucose,
Ca2+,
phosphate (PO4),
pulse oximetry,


Hyperventilation syndrome
Investigations
arterial blood gas (ABG) [in HVS: pH normal, PaCO2 and bicarbonate (HCO3) low],
toxicology,
ELISA,
D-dimer (PE),
ECG,
CXR,
possibly ventilation/perfusion (V/Q) scan.

Hyperventilation syndrome

Investigations
Repeating these investigations at later presentations should only be done if there are new clinical findings.

Hyperventilation syndrome

Management
Acute management
If serious underlying pathology excluded, management includes:
Reassuring the patient.
Alleviating severe anxiety (e.g. use of BDZs).
Establishment of normal breathing pattern (instructing the patient to breathe more abdominally using the diaphragm; physically compressing the upper chest and instructing the patient to exhale maximally to reduce hyperinflation).


Hyperventilation syndrome
Management
Acute management
Note: use of rebreathing techniques (e.g. into a paper bag) is no longer recommended due to reports of significant hypoxia and death.
This form of rebreathing may be unsuccessful anyway because very distressed patients have difficulty complying with the technique and because CO2 itself may be a chemical trigger for anxiety.

Hyperventilation syndrome

Management
Further management
Education, e.g. hyperventilation, relaxation, and breathing techniques
Formal breathing retraining (usually provided by physiotherapists) is available in some centres.
β-blockers and BDZs may be of some use.
Some success reported for use of antidepressants in preventing further episodes.
If there is clear psychiatric morbidity (e.g. anxiety or depression), this should also be specifically addressed.