ABG INTERPRETATION IN SEPSIS

Abnormal arterial blood gas (ABG) among patients with sepsis is an important prognostic indicator. 

 What is ABG?

An arterial blood gas (ABG) analysis is a blood test that measures a patient's oxygen and carbon dioxide partial pressures, as well as their acid-base balance. The results of an ABG analysis can help a healthcare provider determine if a patient is having trouble getting oxygen into their system, or if they are using supplemental oxygen effectively. 

 WHAT IS THE ROLE OF ABGS IN SEPSIS?

Sepsis is a severe, life-threatening condition caused by the body's response to an infection, which can lead to widespread inflammation, organ dysfunction, and in some cases organ failure. Arterial blood gases (ABGs) are a key diagnostic tool in evaluating the severity of sepsis and its impact on the body.

Now let’s understand the key factors of ABGs

Glossary of terms used in ABG analysis:

pH: Acid content of the blood

PaCO2: Carbon dioxide content of the blood

PaO2: Oxygen content of the blood

HCO3: Bicarbonate content of the blood

SaO2: Percentage of hemoglobin saturated with oxygen

Hypoxia: Inadequate oxygenation of the tissue

Hypoxemia: Low oxygen content in the blood

Hypercarbia: High carbon dioxide content

Acidemia: Too much acid in the blood

Alkalemia: Too many buffers in the blood

Compensation: Ability of the body to stabilize acid-base imbalances

Normal values for ABGs:

pH: 7.35 to 7.45

PaCO2: 35 to 45 mm Hg

PaO2: 80 to 100 mm Hg

HCO3: 22 to 26 mEq/L

SaO2: 95 to 100%

How to interpret ABG:

Step 1:

To perform an ABG analysis, a healthcare provider will insert a needle into an artery and draw blood. The sample must be analyzed within 10 minutes to ensure accurate results.

Below is the visualization of sepsis Analysis of ABG Patient count with Hour. Sepsis can escalate quickly. Within hours, a patient can deteriorate from a relatively stable condition to severe sepsis or septic shock. This rapid progression needs immediate attention. With the given dataset we can see as Hour Increases Patient count decreases.

Step 2: 

Determine if pH is Acidosis or Alkalosis. 

If pH is less than 7.35 then (acidosis) If pH is greater than 7,45 then (alkalosis)

Step 3:

Determine if the issue is Respiratory or Metabolic

Carbon dioxide (Paco2) is being regulated by the lungs. Abnormal: If Paco2 is outside of the normal range means it is a respiratory issue Bicarb (Hc03) is being regulated by the kidneys. Abnormal: this would mean a metabolic issue. So basically Carbon dioxide(pac02) =Acid Bicarb (HC03) =Base

 ICU length of stay is also a significant factor in Sepsis Analysis. Prolonged ICU stays can increase the risk of complications such as Organ dysfunction, secondary infections, or extended monitoring and support. These complications can further extend the ICU stay and impact recovery. 

The below Petal Chart visualization can give us a clear picture of average ICULOS in sepsis and non-sepsis patients. As we can interpret Metabolic Alkalosis has the highest ICU length of stay among Sepsis Patients.

Step 4:

Determine if it is full compensation or partial compensation

When interpreting an arterial blood gas (ABG), the presence of compensation is evaluated to determine if the body is trying to correct an imbalance. 

Be sure to remember these 2 things:

when there is a Respiratory problem (Pac02), our body will compensate with Bicarbonate

when there is a metabolic problem (HC03), our body will compensate with carbon dioxide

Compensation can be full or partial:

Uncompensated: if PaCO2 or HCO3 is normal and the other is abnormal. Full compensation: The pH is within the normal range. Partial compensation: The pH is not within the normal range, but either the PaCO2 or HcO3 value is changing to compensate for the primary acid-base complications.

 Now let’s take a look at septic shock analysis in sepsis

SEPTIC SHOCK:

The medical definition of “shock” is a drop or fall in blood pressure. When it is associated with sepsis, it is called septic shock.

Septic shock is a serious medical condition that can occur when an infection in your body causes extremely low blood pressure and organ failure due to Sepsis. Septic shock is life-threatening and requires immediate medical treatment. It’s the most severe stage of sepsis

Sepsis has 3 stages:

• SIRS Systemic Inflammatory Response Syndrome (SIRS): This initial stage is characterized by a variety of symptoms, including fever, increased heart rate, and rapid breathing

• Severe Sepsis: The second stage is diagnosed when acute organ dysfunction begin

• Septic shock. Septic shock is the most severe stage of sepsis.

Any infection can lead to sepsis which can then develop into septic shock if it worsens. Not every infection will lead to sepsis or septic shock. But, if an infection causes enough inflammation, it can develop into sepsis. Most of the common infections are from Complications and bacteria, but both viruses and fungi can also cause infections and sepsis.

Complications:

One of the most serious septic shock complications is organ damage. In some cases, the damage may only be temporary. For example, a person in septic shock may develop acute kidney injury.  The kidneys aren’t able to filter out the toxins from the blood. If this occurs, the patient may need dialysis, a procedure where a machine acts as the body’s kidneys to cleanse the blood. As the body heals, the kidneys may begin functioning again. But in many cases, organ damage is permanent.

Treatment:

Treating septic shock focuses on increasing the blood pressure, eliminating the infection that triggered the sepsis, and providing support for the organs that are failing.

Once the blood pressure is back up to normal levels and it stays there, the patient is no longer in septic shock. The patient is still very ill, but no longer with a too-low blood pressure.

 As we understand what is Septic Shock with the above Visualization, we can see that Uncompensated Respiratory acidosis has the highest number of patients with septic shock.

Conclusion:

Arterial blood gas analysis is used to measure the pH and the partial pressures of oxygen and carbon dioxide in arterial blood. The investigation is relatively easy to perform and yields information that can guide the management of acute and chronic illnesses. This information indicates a patient's acid-base balance, the effectiveness of their gas exchange, and the state of their ventilatory control.

In the simplest terms, if pH is within the range of 7.35 -7.45 the acids and alkalis within the blood are correct.

Understanding ABG results and their significance in the early detection and diagnosis of disorders enables healthcare professionals to formulate effective treatment strategies and improve patient outcomes.

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