Which of the following is not a component of APACHE score ?
**Core Concept**
The Acute Physiology and Chronic Health Evaluation (APACHE) score is a widely used severity-of-disease classification system in intensive care units (ICUs). It assesses a patient's physiological and clinical parameters to predict mortality. The APACHE score includes various components that evaluate the severity of disease.
**Why the Correct Answer is Right**
The APACHE score primarily consists of six components:
* Age
* Chronic health conditions (such as liver disease, cancer, or heart disease)
* Number of comorbidities
* Glasgow Coma Scale (GCS) score
* Blood urea nitrogen (BUN) level
* Serum sodium level
* Heart rate
* Mean arterial blood pressure
* Respiratory rate
* Oxygenation (PaO2/FiO2 ratio)
* Temperature
* White blood cell count (WBC)
However, the APACHE II score does not include the PaO2/FiO2 ratio, which is a component of the APACHE III and IV scores. Therefore, the PaO2/FiO2 ratio is not a component of the APACHE II score.
**Why Each Wrong Option is Incorrect**
**Option A:** Age is a component of the APACHE score, as it takes into account the patient's age and its potential impact on mortality.
**Option B:** Chronic health conditions are a component of the APACHE score, as they can affect a patient's overall health and disease severity.
**Option C:** Glasgow Coma Scale (GCS) score is a component of the APACHE score, as it evaluates a patient's level of consciousness.
**Option D:** The PaO2/FiO2 ratio is not a component of the APACHE II score, but it is included in the APACHE III and IV scores.
**Clinical Pearl / High-Yield Fact**
When using the APACHE score, it is essential to note that the weightage of each component may vary between different versions of the score (e.g., APACHE II, APACHE III, and APACHE IV). Additionally, the APACHE score should be used in conjunction with clinical judgment to assess a patient's disease severity.
**Correct Answer: D. The PaO2/FiO2 ratio is not a component of the APACHE II score.**