Refractory Shock

What is Refractory Shock?

Shock is a condition where the body isn’t getting the oxygen and nutrients it needs. This happens when the circulatory system, which is responsible for circulating blood throughout the body, fails to deliver an adequate supply of blood to various tissues. This failure could also result in inadequate removal of waste materials from the body. The most common type of shock in children is due to low blood volume, while in adults, it’s typically due to a severe infection known as septic shock.

Severe shock that persists despite different medications, oxygen therapy, and fluid replenishment is known as refractory shock. Shock management usually starts with supplying fluids and medications that narrow blood vessels and raise blood pressure, known as vasopressors. However, improper handling of these treatments can have negative effects. Overusing fluids could overload the lungs causing fluid accumulation (pulmonary edema), low oxygen in the body, and swelling of organs. Likewise, too much of the vasopressors could trigger irregular heart rhythms and blockages in the blood vessels.

The amount of these medications needed to keep the average blood pressure within a normal range can indicate the patient’s likelihood of survival. For instance, high doses of norepinephrine, a type of vasopressor, can suggest a higher risk of mortality. Unfortunately, there is no definitive guideline for treating severe, unresponsive shock, but researchers have conducted a few studies to help guide medical professionals in managing such cases.

What Causes Refractory Shock?

Refractory shock is a specific type of shock in which blood vessels dilate or widen due to a reduced reaction to chemical messengers involved in controlling blood pressure. An overload of a substance called nitric oxide (NO), which can have a relaxing effect on blood vessels, or a lack of certain hormones such as vasopressin, cortisol, vitamin B1, ascorbic acid, and angiotensin II are involved in this process.

This condition can result in excessive relaxation of the blood vessels, allowing blood to flow too freely and thus leading to a drop in blood pressure. Additionally, conditions such as low oxygen levels, an overly acidic body environment, and elevated lactate levels (markers of tissue breakdown) can activate complex mechanisms inside smooth muscle cells which line our blood vessels. This prevents calcium, an important component for muscle tone and contraction, from entering these cells, further hindering their ability to constrict and manage blood flow.

Risk Factors and Frequency for Refractory Shock

When there’s a cardiovascular failure, it often leads to a condition known as refractory vasodilatory shock. This condition typically occurs after septic shock. It’s a very serious health issue with more than 50% of people not surviving. In fact, around 6% to 7% of very sick patients in the ICU may develop this kind of shock.

Signs and Symptoms of Refractory Shock

Refractory shock is a severe condition where the body’s organs start to fail. In examining someone with refractory shock, doctors look for specific signs based on the impact on different organs. Some of these signs include confusion (central nervous system), low blood pressure and heart failure (cardiovascular system), decreased urine output (kidneys), gut complications such as a halt in digestion or reduced blood flow (gut), rapid breathing or severe breathing difficulties (respiratory system), and slow blood refill in the capillaries (skin).

Doctors also monitor the person’s oxygen delivery to determine the severity of the condition. They take into account factors like breathlessness, slow capillary refill, level of consciousness (measured using the Glasgow Coma Scale), urine production, as well as objective measurements (like lactate levels, mixed venous saturation, heart rate, and blood pressure).

• Confusion (Central nervous system)
• Low blood pressure (Cardiovascular system)
• Heart failure (Cardiovascular system)
• Decreased urine output (Kidneys)
• Halt in digestion or reduced blood flow (Gut)
• Rapid breathing or severe breathing difficulties (Respiratory system)
• Slow blood refill in capillaries (Skin)
• Breathlessness
• Consciousness level (Glasgow Coma Scale)
• Urine production
• Lactate levels
• Mixed venous saturation
• Heart rate
• Blood pressure

Testing for Refractory Shock

In trying to find out the primary cause of shock, a condition that occurs when your organs are not getting enough blood and oxygen, doctors need to investigate any possibilities for what might be worsening the condition – like low blood volume (hypovolemia), heart failure (pump failure), or physical blockages (obstruction). To make sure they can react quickly to any changes in the patient’s condition, patients will be put on continuous monitoring for heart and lung function.

Various lab tests will be done, including a complete blood count (to check overall health and detect a wide range of disorders), a basic metabolic profile with liver function tests (to assess how well the liver is working), a disseminated intravascular coagulation panel (to monitor any issues with clotting), arterial blood gas (to check oxygen and carbon dioxide levels), and urinalysis (to check the overall health and identify any kidney disorders).

Doctors would also get samples for cultures from blood, urine, wound, and if applicable, from the trachea (windpipe) as well, as it can help identify any infections that might be present. They would also be checking for inflammation markers such as C-reactive protein or procalcitonin and lactate levels (substances released by cells when there isn’t enough oxygen).

Finally, patients also get a chest x-ray, a quick and painless test that takes images of the structures within your chest, such as your heart, lungs, and blood vessels. It is particularly helpful to help monitor the severity of Acute Respiratory Distress Syndrome (ARDS), a serious condition where fluid builds up in the lungs.

Treatment Options for Refractory Shock

The first step in managing a condition is to identify and treat the root cause. When it comes to treating shock in its early stages, it’s crucial to act quickly to prevent it from getting worse. There are different ways to treat shock, including giving fluids in the case of hypovolemic shock, or medications called vasopressors in more severe cases. The goal for most adults is to keep the average blood pressure above 65 mmHg. Norepinephrine is commonly used in cases of septic shock. If the shock results in a low flow of blood to the heart, epinephrine might be the preferred treatment. Sometimes, a combination of vasopressors can work better to prevent the shock from getting worse.

Vasopressin, another drug that helps contract blood vessels, is often lacking in patients with sepsis. This drug works well in an acidic environment and does not cause heartbeat irregularities. It has been observed to decrease the need for other drugs and is linked to lower death rates in less severe shock. Similarly, using it with another medication, like a corticosteroid, can decrease mortalities.

Doctors are urged to minimize the use of sedatives, as they can worsen low blood pressure through widening blood vessels and causing heart muscle depression. If a patient with sepsis is dependent on a ventilator, it’s advised to limit sedative use.

Continuous renal replacement therapy (CRRT) is a treatment method that can rapidly control body temperature and correct metabolic acidosis in patients with shock. This therapy can reduce the need for vasopressors and improve heart function. However, there is a risk of removing vital substances from the body, such as antibiotics and vitamins. Still, with proper management, these can be supplemented appropriately

Various treatments can be used if shock becomes hard to control (refractory). However, none of these therapies has shown definite mortality reduction or superiority over others. Those treatments include glucocorticoid therapy, which reduces inflammation and resultant vessel dilation. Correction of acidemia or acid build-up in the body can improve how well vasopressors work. Calcium supplementation can help as low calcium levels often occur in severe sepsis and can lead to low blood pressure. Vitamin C and B1 are also essential for body functions and can be supplemented. Some medications like methylene blue and hydroxocobalamin can reverse the blood-vessel widening caused by high nitric oxide levels. Advanced treatments, like extracorporeal membrane oxygenation (ECMO), can provide temporary support to heart and lung functions in severe cases.

Looking into the future, more treatments are being researched and developed. These include terlipressin and selepressin, both analogs of vasopressin and synthetic human angiotensin II, a hormone that regulates blood vessel contraction and water balance in the body.

What else can Refractory Shock be?

Here are a few different types of shock a person can experience:

• Septic shock
• Vasodilatory shock
• Cardiogenic shock

What to expect with Refractory Shock

Refractory shock, a condition where the body’s blood pressure remains dangerously low despite treatment, often has a high risk, with up to 60% of patients not surviving. The severity of a patient’s illness, reflected by the amount of vasopressor medication needed to stabilize their blood pressure, is the most significant factor influencing their survival chances.

Vasopressors are a type of medicine used to raise blood pressure. Reports have shown that using vasopressin and angiotensin II, two types of these medications, results in lower death rates among patients with less severe forms of shock. This effect is seen specifically in those whose initial norepinephrine needs (another type of vasopressor) are less than 15 mg/min.

Possible Complications When Diagnosed with Refractory Shock

Severe consequences in extreme conditions may include:

• Dysfunction of certain body organs
• Failure of multiple organs in the body
• Death

Preventing Refractory Shock

Starting the treatment which involves combining different medications that increase blood pressure (known as vasopressors) as early as possible has shown to improve survival rates. Shock, a critical condition where the body isn’t getting enough blood flow, can be treated with medications like hydrocortisone and vasopressin. Studies have indicated that when vasopressin and a medicine called angiotensin II are used together, it significantly reduces the chance of death in patients suffering from less severe forms of shock.