Repeated or continuous monitoring of patient’s all physiological functions in critical conditions (such as pre surgery, during surgery , post surgery, cases of extreme disease or accident) is very crucial to make therapeutic interventions, and assessment of those interventions and hence the quality of clinical decisions depends in part on the quality of information available to the decision-maker.
This visual display and monitoring of all physiological or electrical signal and vital signs coming from the life support devices connected to patient is achieved through multi parameter health monitor. It can also store, organize, and report data which is integrated and correlated from multiple sources and generate alarms when unsafe conditions occurs.
What are the essential parameters monitored ?
1). ECG (Electrocardiogram): It helps in detecting cardiac(heart) abnormalities instantly by continuously measuring heart’s electrical rhythmical activity using the skin electrodes correctly placed on chest.
2).Oxygen Saturation: It refers to concentration of oxygen in blood measured by pulse oximeter, A range of 96% to 100% is generally considered normal. Anything below 90% could quickly lead to life-threatening complications.
3).Respiration Rate: The number of breaths per minute or, more formally, the number of movements indicative of inspiration and expiration per unit time. A normal breathing rate for an adult at rest is 12 to 16 breaths per minute.
4). Body Temperature: Temperature sensor such as thermistor is used for continuous or Predictive monitoring within 1°C accuracy, Body temperature may be abnormal due to fever (high temperature) or hypothermia (low temperature i.e. below 35°C). It is very important during surgery Anesthetic-induced impairment of normal thermoregulatory control, and the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients.
5).Invasive Blood Pressure: This technique involves direct measurement of arterial pressure by inserting a cannula needle in a suitable artery. The cannula must be connected to a sterile, fluid-filled system, which is connected to an electronic patient monitor. The advantage of this system is that a patient’s blood pressure is constantly monitored beat-by-beat, and a waveform (a graph of pressure against time) can be displayed.
The very first advantage of IBP is that it allows continuous and accurate ‘beat-to-beat’ blood pressure monitoring. This is useful in patients who are likely to display sudden changes in blood pressure (e.g. vascular surgery), in whom close control of blood pressure is required (e.g. head injured patients), or in patients receiving drugs to maintain the blood pressure.
Other advantages include the fact that intravascular volume status can be estimated from the shape of the arterial pressure trace, and that the indwelling arterial cannula is convenient for repeated arterial blood sampling, for instance for arterial blood gases.
6).Carbon-dioxide Monitoring (CO2): Affordable, portable monitors are available to measure exhaled CO2 (End Tidal CO2) . These units consist of a monitor with a pump (to obtain respiratory gases), and a sampling line with an adaptor that attaches between the endotracheal tube and the breathing hose. Capnographs usually work on the principle that CO2 absorbs infra-red radiation. The presence of CO2 in the gas leads to a reduction in the amount of light falling on the sensor, which changes the voltage in a circuit.
Normal ETCO2 levels are 35-45 mmHg. The most common cause of increased ETCO2 is hypercapnia secondary to anesthetic-induced hypoventilation.
References and Further reading:
- http://my.clevelandclinic.org/health/healthy_living/hic_Pre-participation_Evaluations/hic_Vital_Signs
- http://www.emergencycareforyou.org/VitalCareMagazine/ER101/Default.aspx?id=500
- http://en.wikipedia.org/wiki/Monitoring_%28medicine%29
