```json
{
	"no": ["no"], 
	"yes": ["yes"] 
}
```

Based on the feature "NITR_S" which represents the use of liquid nitrates in the ICU, the dictionary indicates that for patients without chronic heart failure (target class "no"), the only possible value for the feature is "no". Similarly, for patients with chronic heart failure (target class "yes"), the only possible value for the feature is "yes".