# Predicting Decompensation Risk in Intensive Care Unit Patients Using Machine Learning
## 4 Discussion
### Key Risk Factors in Decompensation Prediction  
The CNN-LSTM model highlights that variables such as oxygen saturation, prot thrombin time (PT), platelet count, heart rate, and blood pressure are key risk factors of decompensation, as shown in Figure 8.  
Reduced oxygen saturation has also been previously identified as one of the factors associated with clinical deterioration [19; 20; 21]. In the case of PT, high levels of it can be associated with patient deterioration [22; 23; 24], but the significance and appropriate response depend on the individual patient's medical history and the underlying causes of the elevated PT.  
Platelet count is not typically considered a decompensation marker on its own, although abnormalities in platelet count can indicate various medical conditions, e.g., a low platelet count is common in patients with cirrhosis, and it may indicate a more serious and advanced nature of the condition and an increased risk of complications [25; 26]. Abnormal platelet counts can also be related to cancer, and cancer patients who are critically ill may be more susceptible to decompensation compared to individuals without cancer [27; 28]. Elevated platelet counts (thrombocytosis, greater than 450 \(\times\) 109/L) can be a marker for potential cancer, including lung, endometrial, gastric, oesophageal, or colorectal cancer. The association of low platelet count (thrombocytopenia, below 150 \(\times\) 109/L) with cancer includes systemic chemotherapy, radiation, metastatic cancer, and haematological malignancies [29; 30].  
Both low and high heart rates can be associated with patient decompensation, but the significance of heart rate abnormalities depends on the clinical context and underlying causes. Low heart rate (bradycardia) can be a sign of decompensation in certain situations [31], especially if it leads to reduced cardiac output and insufficient blood supply to vital organs. It can be associated with conditions like heart block, severe conduction system abnormalities, or drug toxicity, which may contribute to decompensation. High heart rate (tachycardia) can also be associated with decompensation, particularly if it results from underlying heart disease or other medical conditions [32; 33; 34; 35], e.g., atrial fibrillation [36; 37; 38; 39], ventricular tachycardia [40; 41], or severe systemic infection [23; 42], which may contribute to decompensation.  
Blood pressure can be an important factor in assessing the risk of patient decompensation, particularly in the context of cardiovascular health [43; 44]. Prolonged hypertension can contribute to chronic vascular damage and increase the risk of conditions like stroke [45], heart attack [43; 44], kidney disease [46; 47], and vascular diseases [48; 49]. While hypertension itself is not a direct marker of decompensation, it is a risk factor for the development of various cardiovascular and cerebrovascular complications, which can lead to decompensation. Hypotension, in turn, can be associated with conditions such as shock [50], heart failure [51], or sepsis [52], and it is considered a risk factor for decompensation in these cases. In ICU patients, hypotension can be indicative of various underlying issues and can lead to complications [52; 53], including multi-organ failure, cerebral hypoperfusion, and poor outcomes.