Patient monitoring involves both non-instrumental and instrumental methods. Non-instrumental monitoring includes clinical observation of a patient's appearance, breathing, bleeding, and positioning. Instrumental monitoring provides data through devices like ECGs, which measure heart rate and rhythm, blood pressure cuffs, pulse oximeters, capnography, and temperature monitors. Direct arterial blood pressure monitoring via an intra-arterial catheter provides continuous, beat-to-beat pressure readings but carries risks like infection, while noninvasive blood pressure methods take intermittent readings and avoid invasiveness. Together, non-instrumental observation and instrumental monitoring devices provide clinicians vital information to care for patients.