What is Carbon Dioxide Embolism?
Laparoscopic surgery, a minimally invasive procedure using small incisions and a tiny camera, has become widely used in the medical field. One common technique in these surgeries is gas insufflation, where gas is used to inflate the body to create space and improve the surgeon’s view. This technique is usually used for surgeries in the belly area, particularly for digestive and female reproductive system surgeries. Carbon dioxide (CO2) is commonly used for this purpose since it’s colorless, inexpensive, doesn’t catch fire, and dissolves more easily in blood than air. This last property reduces the risk of complications if gas accidently enters the veins.
However, using CO2 gas in this way does have some risks. The primary risk is a carbon dioxide embolism, where gas bubbles block blood vessels. Although small embolisms (called micro embolisms) are common during a laparoscopy, significant embolisms that impact the patient are rare and can be life-threatening. How severe the embolism is depends on the amount of gas involved. Symptoms can range from none at all to serious circulatory problems, even death. The remaining part of this topic will discuss the occurrence, causes, signs, treatment, and prevention of carbon dioxide embolisms during laparoscopic surgery.
What Causes Carbon Dioxide Embolism?
During laparoscopic surgeries, a gas bubble (known as an ’embolism’) made out of carbon dioxide (CO2) might form in the body. This typically happens when a tool called the Veress needle accidentally punctures an organ or a large blood vessel. Laparoscopic surgeries are procedures that use a camera and small tools to perform surgery through tiny incisions.
The process of inserting the Veress needle and filling the area with CO2 (a process known as ‘insufflation’) is done without the surgeon being able to see exactly what’s happening. This can increase the risk of an embolism.
An embolism that occurs later may be linked to damaged blood vessels. This damage can allow CO2 to enter your bloodstream from the area where the surgery happened.
Risk Factors and Frequency for Carbon Dioxide Embolism
CO2 embolism, or a gas bubble in the bloodstream, is a very rare occurrence. A recent study found that it only happened in 7 out of 489,335 laparoscopic surgeries (which is a miniscule 0.001% of cases). When a monitoring technique known as transesophageal echocardiography (TEE) was used during these surgeries, the reported incidence of any amount of gas embolism varied quite a bit. Indeed, the reported rates of CO2 embolism ranged from a low of 6.25% to as high as 100% of monitored surgeries. Despite these differences in reporting, it’s important to remember that a significant CO2 embolism can be deadly, with a mortality rate reaching up to 28%.
Signs and Symptoms of Carbon Dioxide Embolism
A CO2 embolism, which is a bubble of gas blocking blood flow in your body, can sometimes be small and cause no symptoms, resolving on its own. Some signs of gas embolism include:
- Systemic hypotension: Low blood pressure throughout the whole body
- Tachypnea: Breathing rapidly
- Dyspnea: Difficulty breathing
- Cyanosis: Bluish color of the skin due to low oxygen levels
- Tachycardia or bradycardia: Heart beating too fast or too slow
- Arrhythmia: Irregular heartbeat
- Asystole: Absence of heart contractions
- “Mill-wheel” splashing auscultatory murmur: A specific sound heard through a stethoscope when listening to the heart
Paradoxical embolism, a type of embolism that somehow ends up affecting a different part of the body than where it originated, may cause changes in mental status, specific neurological symptoms, or loss of consciousness.
Testing for Carbon Dioxide Embolism
Transesophageal echocardiograms (abbreviated as TEE), which are special types of ultrasound tests, are very efficient at detecting silent or “subclinical” bubbles of Carbon dioxide (CO2) in your veins, even when these bubbles are very small. This test involves using a special device to get views of your heart from inside your esophagus, or food pipe. It has been shown to be particularly good at identifying CO2 embolism, which is a life-threatening condition where gas bubbles block blood vessels.
Alternatively, transesophageal Doppler, another type of ultrasound technique, is also very sensitive. It’s a cheaper option than TEE, but can be just as effective. Precordial Doppler is another method that can be used, though it may not be as accurate due to the position of the probe that picks up the sound waves.
During surgery, standard noninvasive monitors can help detect potential CO2 embolism, although they are usually less sensitive compared to the aforementioned techniques. For example, a 5-lead EKG, which is a test that checks for problems with the electrical activity of your heart, may stick on changes suggesting strain on the right side of the heart. This can occur as a result of CO2 bubbles blocking up the vessels.
Certain signs during your surgery, like a sudden drop or complete loss of end-tidal CO2 (the amount of carbon dioxide released as you exhale), can indicate a serious decrease in the amount of blood available to the heart due to gas embolism. Other measures such as continuously monitoring the pressure in the pulmonary artery, the vessel carrying blood from the heart to the lungs, can also be used to check for the development of gas embolisms.
Treatment Options for Carbon Dioxide Embolism
If a surgeon suspects that a CO2 (carbon dioxide) embolism has occurred during a procedure, they’ll immediately stop insufflating, or filling the abdomen with gas. This is because the embolism – a gas bubble trapped in the body’s blood vessels – could be causing a blockage. Sometimes, when the pressure in the abdomen is reduced, there might be some bleeding as the embolism could have resulted from damage to a blood vessel.
To help move this trapped gas bubble, the patient might be put in a specific position known as the Durant or Trendelenburg position. This position guides the gas bubble towards the top of the right ventricle (a chamber in the heart) and away from the pulmonary artery, which can help prevent more significant health problems.
The patient might also be given 100% oxygen to breathe. This helps remove the CO2, improve the balance between ventilation (air movement in and out of the lungs) and perfusion (blood flow to the lungs), and address low oxygen levels in the blood. They might also be made to breathe faster to help eliminate CO2 from the body.
In surgeries with a high risk of air embolism (for example, certain brain surgeries), a multi-orifice central venous catheter may be placed. This is a thin tube insered into a large vein, used to perform an aspiration, a procedure to remove the gas bubble. However, in unexpected cases of CO2 embolism, the central venous catheter would be more useful for administering medications that constrict the blood vessels, although aspiration could still be attempted.
Hyperbaric oxygen therapy, which involves breathing pure oxygen in a pressurized room, can be used to reduce the size of the gas bubble in patients experiencing neurological deficits, or damage to the nervous system. If the CO2 embolism causes severe cardiovascular collapse, or a sudden failure of the blood circulation system, supportive treatment with fluids, medications that constrict the blood vessels, and a heart-lung machine may be necessary.
What else can Carbon Dioxide Embolism be?
When a doctor suspects a carbon dioxide embolism, there are several other conditions they should consider before making a diagnosis. These conditions include:
- Air embolism
- Pulmonary embolism
- Pneumothorax
- Bronchospasm
- Pulmonary edema
- Hypovolemia (low volume of blood)
- Cardiogenic shock (heart failure)
- Myocardial infarction (heart attack)
- Septic shock (a severe infection causing low blood pressure)
- Electromechanical dissociation (irregular heart rhythm)
- Cerebral hypoperfusion (reduced blood flow to the brain)
- Stroke
- Other types of embolisms, like ones caused by amniotic fluid or fat
What to expect with Carbon Dioxide Embolism
The outlook can change based on the size of the blood clot and how severe the signs and symptoms are.
Possible Complications When Diagnosed with Carbon Dioxide Embolism
The complications that can occur due to carbon dioxide embolisms can be quite serious. These include:
- Cardiac arrest – a sudden loss of heart function
- Neurological sequelae – issues with the nervous system like motor (movement) deficits, cognitive (thinking) deficits, or seizures
- Death
Preventing Carbon Dioxide Embolism
The prevention of a CO2 embolism – a potentially dangerous condition where gas bubbles enter the bloodstream – focuses on blocking possible ways for the gas to enter the bloodstream during keyhole surgery. It’s crucial that the Veress needle – a special needle used in this type of surgery – is placed correctly. This can be confirmed by pulling the plunger back (aspiration) and checking for any blood. If none is present, the needle is probably in the right place. This is followed by slowly introducing the gas (insufflation) into the body under low pressure.
If using the Veress needle causes any issues, other methods of entering the body and creating space for the operation (pneumoperitoneum) should be considered. Using lower pressure when introducing the gas can potentially lessen the pathophysiological (how the operation impacts the body’s normal functions) changes.
Once the instruments (trocars) are properly placed, the patient should be put in the Trendelenburg position, meaning that they’re laid flat on their back with their feet higher than their head. This helps reduce pressure in the abdominal area during the surgery.
Putting the patient under a positive end-expiratory pressure (PEEP) of 5 cm H2O can be helpful during the operation to help prevent lung collapse (atelectasis) that can be caused by the gas used to create space inside the abdomen (pneumoperitoneum).