Non Invasive Monitoring. Is it Time to Monitor the Monitor?
The digital era has led to the birth of an array of patient monitoring systems for use in a wide range of outpatient and inpatient environments. They may range from monitors suitable for monitoring a single parameter to others with multi-parameter capabilities.
In the course of this blog, I have chosen to use the example of the commonly used non invasive monitoring systems – multi-parameter hemodynamic monitors [pulse oximetry (SpO2), non-invasive blood pressure (NIBP), heart rate and respiratory rate (RR)].
I have observed off and on that there appears to be a lingering misconception about patient monitoring among some nursing personnel as well as among some doctors. To obtain the maximum out of monitoring, it must be understood that although the “absolute” values displayed on the monitor screen are important, they are of only of secondary importance. Most crucial information that monitor provides is what is known as “TRENDING”. The monitor provides in real time the trends for each parameter recorded. To put it more simply, the monitor answers the following questions: Is a parameter remaining stable? Is a value showing an increasing or decreasing trend or is it fluctuating erratically? Is there a sudden change?
I will go on to try and explain how some of the misconceptions concerning patient monitoring affect patient care with the aid of few hypothetical scenarios based on what I had witnessed in real life.
Scenario 1: A doctor enters the Intensive Care Unit (ICU) and notices that the monitor is not displaying the NIBP value. The nurse explains that the systolic blood pressure that was shown on the monitor screen was consistently 10 millimeters (mm) of Mercury (Hg) less than the value as recorded using the good old sphygmomanometer (manual recording) and so he/she decided to discontinue recording NIBP! . What happens in this situation is simple – trending gets sacrificed in favor of an obsession for an “accurate” value. Any sudden change in the patient’s condition for the worse has the potential to go unnoticed. The alternate (more sensible) approach should have been to continue NIBP monitoring supplemented by periodic manual recording.
Scenario 2: An intern completes her ICU rounds. The monitor of her patient had shown the following parameters: NIBP of 100/70 mm of Hg, SpO2 of 98%, an RR of 19/min and a heart rate of 92/min. The intern returns after 15 minutes, opens the door of the ICU and peeps in to look at her patient’s monitor. The monitor shows the following parameters: NIBP of 100/70 mm of Hg, SpO2 of 99% , a RR of 17/min and a heart rate of 90/min. Satisfied, the intern leaves and returns after another 30 minutes and peeps in once again. Monitor shows the following parameters: NIBP of 100/70 mm of Hg, SpO2 of 95%, an RR of 20/min and a heart rate of 96/min. Our intern is now almost convinced about the hemodynamic stability of her patient as the NIBP was remaining unchanged. What she did not realize is that the monitor had been set by someone to record NIBP (Repeat Cycles) every one hour! It is known widely (atleast among the anesthetists) that in most monitors, a wide range of ‘Repeat Cycles’ (1 ~ 10, 15, 30, 60, 90, 120 minutes) are available for the NIBP recording.
Scenario 3: It is one of those unusual days in which the ICU for once has only one patient. The doctor enters the ICU and is greeted by unusual silence- none of the usual beeps or alarms! As the patient was fairly stable for some time, the nursing staff decided to switch off the audible alarms on the monitor to enjoy one of those extremely rare periods of peace and calm. Doctor reaches the patient’s bedside and discovers that his patient is at the brink of death. This scenario demonstrates the importance of beeps and audible alarms incorporated in monitors (although they are often annoying or irritating). Gagging a monitor may not be a good idea, after all!
These scenarios are meant to impress on the medical students that in order to get the best out of patient monitoring, it may be worth monitoring the monitor.
About the Author: Dr. Aroon Kamath is a retired general surgeon from Father Muller Medical College, Mangalore, India as an Assistant Professor. He loves to teach, write for medical blogs and conduct medical quizzes. He can be reached at: [email protected]
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