BLOOD GAS IMBALANCE: KNOW THE DANGERS OF HYPERCAPNIA
Medically Reviewed by Dr. Sony Sherpa, (MBBS)
You may have heard of carbon dioxide (CO2) in the context of climate change, yet did you know that high levels of CO2 in your blood can also be dangerous? This condition is known as hypercapnia, which can have severe health consequences.
This blog explains what hypercapnia is, its types, how it occurs, the symptoms, and how it can be treated and prevented.
What is Hypercapnia?
Hypercapnia is a medical condition caused by higher-than-usual levels of carbon dioxide in the blood. It can occur when the body cannot get rid of excess CO2 through the lungs, leading to a buildup in the bloodstream.
Normal CO2 levels in the blood range from 35 to 45 mmHg.[1] The body eliminates excess CO2 through the respiratory system by exhaling it with each breath. Hypercapnia often occurs due to a V/Q mismatch, where the ventilation (airflow) and perfusion (blood flow) in the lungs do not align properly, leading to an accumulation of CO2 in the blood.
Two main mechanisms can cause hypercapnia: respiratory and metabolic.
Respiratory hypercapnia occurs when a lung or respiratory system problem prevents the body from expelling excess CO2. This type can occur due to respiratory conditions, with chronic obstructive pulmonary disease (COPD), sleep apnea, and asthma being common examples.
Metabolic hypercapnia occurs when the body produces too much CO2 or cannot get rid of it through normal metabolic processes. Conditions such as diabetes, kidney disease, or liver failure can cause this type.
There are two primary forms of hypercapnia, each with its distinct presentations and severity of symptoms:
Acute hypercapnia is a sudden increase in CO2 levels that overwhelms the body and causes highly acidic blood. This shift leads to rapid and severe symptoms such as confusion, frantic breathing, and loss of consciousness.[2]
Chronic hypercapnia occurs over an extended period and may have milder and more gradual symptoms like fatigue and muscle weakness. In this form, the kidneys compensate for the rise in blood acidity caused by CO2 elevation, resulting in bicarbonate release and a balanced pH.
Hypercapnia vs Hypoxia
Hypercapnia is often confused with hypoxia, a similar yet distinct condition. A lack of oxygen causes hypoxia, while a buildup of carbon dioxide causes hypercapnia.
While these conditions seem related, they arise due to different mechanisms, can occur independently, and have different symptoms.
Symptoms and Complications
High levels of blood carbon dioxide can have a range of symptoms, including:
- Headaches
- Dizziness
- Confusion
- Shortness of breath
- Rapid breathing
- Flushed skin
- Increased heart rate
- Fatigue
- Muscle weakness
- Nausea and vomiting
In severe cases, hypercapnia can lead to respiratory acidosis, a condition where the blood supply to the lungs becomes too acidic due to high levels of CO2. Respiratory acidosis can cause symptoms such as:
- Chest pain
- Irregular heartbeat
- Loss of consciousness (also known as CO2 narcosis[3])
- Coma
If left untreated, hypercapnia can lead to long-term complications, including:
- Chronic respiratory failure
- Pulmonary hypertension
- Heart failure
- Brain damage
- Seizures
- Coma
Causes of Hypercapnia
As reviewed below, many conditions can lead to hypercapnia by affecting the respiratory system.
Individuals with these conditions must work closely with healthcare professionals to manage respiratory symptoms and slow hypercapnia progression.
Respiratory Conditions
The leading cause of hypercapnia is Chronic Obstructive Pulmonary Disease (COPD). COPD is a chronic lung disease that mainly affects smokers and is characterized by gradually advancing limitations to breathing.
In the lungs, air flows through the bronchial tubes into the alveoli. Alveoli are thin-walled sacs facilitating oxygen entry into the bloodstream and carbon dioxide exit. COPD reduces elasticity in bronchial tubes and alveoli, trapping air during exhalation.[4] This obstructs airflow, leading to V/Q mismatch and subsequent hypercapnia in affected individuals.
Other respiratory conditions that affect the lungs or airways and lead to hypercapnia include:[5]
- Sleep apnea
- Asthma
- Bronchitis
- Emphysema
- Pneumonia
- Pulmonary embolism
All of these conditions co-occur frequently in COPD patients.
Neuromuscular
Conditions that affect the neuromuscular system can lead to hypercapnia.[6] Examples include:
- Multiple sclerosis (MS)
- Nerve or spinal cord injuries
- Amyotrophic lateral sclerosis (ALS)
- Muscular dystrophy
- Guillain-Barré syndrome
These disorders can weaken the respiratory muscles, making breathing difficult and causing a buildup of carbon dioxide in the bloodstream.
Neurological diseases and conditions can also lead to hypercapnia, like encephalitis, that inflames parts of the brain responsible for coordinating respiration and the muscles involved.
Anatomical
Apart from neuromuscular causes, differences in chest or spine anatomy can also contribute to hypercapnia by making breathing difficult. Examples include:[7]
Flail chest refers to multiple rib fractures, which can affect the movement of the chest wall and lead to inadequate ventilation.
Ankylosing spondylitis is an inflammatory ailment that affects the spine, causing stiffness, joint fusion, and impaired breathing.
Cardiovascular
Vascular disease and heart failure can contribute to hypercapnia by impairing the blood flow and oxygen exchange in the lungs. Lower blood circulation can lead to a decrease in CO2 removal, resulting in its accumulation in the bloodstream and the development of hypercapnia.
Metabolic Conditions
Metabolic conditions can disrupt the body's normal metabolic processes, causing an imbalance in CO2 production and elimination, ultimately contributing to hypercapnia.
These include:
- Diabetes
- Kidney disease
- Liver failure
- Obesity
- Hypothyroidism
Severe obesity can cause obesity-related hypoventilation syndrome[8], which refers to excess internal fat in the heart and lungs, reduced lung capacity, and respiratory muscle dysfunction. These factors lead to inadequate ventilation and carbon dioxide buildup in the bloodstream.
Oxygen-Induced Hypercapnia
In some cases, hypercapnia can be caused by receiving too much oxygen. Oxygen-induced hypercapnia can happen in medical settings, such as during mechanical ventilation or in people with chronic lung conditions who use supplemental oxygen at home. Those with COPD are particularly vulnerable to O2-induced hypercapnia when receiving oxygen therapy.[9]
Medication and Toxicity
Poisoning and toxicity from medication overdose, particularly sedatives and opioids, can lead to hypercapnia by depressing the central nervous system, impairing respiratory drive, and causing inadequate ventilation, resulting in carbon dioxide buildup in the bloodstream.
Other prescriptions may have similar effects that hamper breathing. Consult your doctor about potential side effects if you notice respiratory symptoms after starting a new protocol.
Genetic
Genetic causes of hypercapnia can include conditions where the body does not produce enough alpha-1-antitrypsin, a protein responsible for protecting the lungs from damage. This deficiency can lead to the development of chronic obstructive pulmonary disease (COPD)[10] and exacerbate the accumulation of carbon dioxide in the blood.
Risk Factors for Hypercapnia
Some people may be more at risk for developing hypercapnia than others. Risk factors include:
- Chronic lung conditions, such as COPD or asthma
- Obesity
- Smoking
- Age (older adults are more at risk)
- Sedentary lifestyle
- Use of certain medications, such as sedatives or opioids
When to See a Doctor
If you experience any symptoms of hypercapnia, it is essential to seek medical attention immediately. If left untreated, hypercapnia can lead to serious complications and it is vital to address it as soon as possible.
Diagnosis of Hypercapnia
To diagnose hypercapnia, your doctor will likely perform a physical checkup, where they will ask about your symptoms and medical history. They may also order tests to measure your blood levels of carbon dioxide and oxygen using an arterial blood gas test or a pulse oximetry test.[11]
Your doctor may also order a chest X-ray or CT scan to rule out any underlying respiratory conditions causing your hypercapnia.
Treatment of Hypercapnia
The treatment for hypercapnia will depend on the underlying cause and severity. With swift treatment, acute hypercapnia tends to resolve faster than chronic hypercapnia.
In some cases, addressing the underlying condition, such as treating a respiratory infection or adjusting medication, may be enough to resolve hypercapnia.
A doctor will create a customized plan for treating the underlying condition.[12]
Medications: A standard treatment for breathing disorders is medications that open the airways or reduce inflammation. Examples include:
- Bronchodilators, or inhalers, to improve airway muscle function
- Corticosteroids which reduce airway inflammation
- Antibiotics for respiratory infections like pneumonia or acute bronchitis
Medications may help patients with COPD more than oxygen therapy, who respond to treatment with oxygen-induced hypercapnia.
Oxygen Therapy: These therapies increase the patient's oxygen levels, often with a ventilator, helping to normalize CO2 levels (except in those with COPD or severe respiratory failure).
Types of oxygen therapy include:
- Non-invasive ventilation for acute or chronic cases
- Oxygen therapy
- Mechanical ventilation (for cases caused by lung collapse)
Surgery is necessary in rare cases comprising:
Lung volume reduction surgery to remove damaged parts of the lung that impact breathing.
Lung transplantation to replace a part or all of a damaged lung.
Management: If you have been diagnosed with hypercapnia, your doctor will likely also suggest the following lifestyle changes to help improve your condition:
- Quitting smoking
- Maintaining a healthy weight
- Staying physically active
- Avoiding exposure to air pollutants
It is essential to stick to your doctor's treatment plan and to have your symptoms monitored. If they get worse, seek medical attention promptly.
Living with Hypercapnia
Living with a chronic condition like hypercapnia can pose challenges in terms of physical limitations, emotional well-being, and social interactions. Those with hypercapnia may struggle to perform daily activities and adhere to exercise routines.
Support from healthcare professionals, family, and support groups can help address these concerns.
Managing symptoms of hypercapnia involves:
- Following medical advice
- Adhering to treatment plans
- Adopting healthy lifestyle choices
- Using assistive devices if needed
- Staying informed about new advancements in treatment options
Prevention of Hypercapnia
While some risk factors for hypercapnia, such as age and chronic lung conditions, cannot be changed, you can take steps to prevent hypercapnia. These include:[13]
- Avoiding exposure to air pollutants
- Avoiding or quitting smoking
- Managing chronic health conditions
- Utilizing supplemental oxygen as prescribed by your doctor
- Seeking prompt treatment for respiratory infections or other illnesses that can affect your breathing
Conclusion
Hypercapnia is a severe medical condition that occurs when too much carbon dioxide is present in the blood. It is commonly caused by respiratory or metabolic conditions. CO2 imbalances can lead to substantial complications if left untreated. If you experience symptoms of hypercapnia, it is crucial to seek medical attention immediately. By knowing more about the causes, symptoms, and treatment options for hypercapnia, you can take steps to manage and prevent this condition.
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