Clinical education resources
Clinical support for blood pressure management and non-invasive blood pressure measurement
The scientific community has called for more training and education on blood pressure (BP) measurement as hemodynamic management continues to be linked to patient outcomes [1]. Understanding measurement limitations and references, device configuration and patient setup are important factors in obtaining accurate BP measurements. Studies show regardless of the method used to measure BP, initial and ongoing training of technicians and healthcare providers and the use of validated and calibrated devices are critical for obtaining accurate BP measurements [2].
Blood pressure methodologies
There are three primary methods for measuring blood pressure:
Intra-arterial line NBP measurement
Automated oscillometric NBP measurement
Fully-manual auscultatory NBP measurement
Which method do Philips monitors use?
Philips IntelliVue monitors use the automated oscillometric NIBP technique to measure the systolic, diastolic, and mean arterial pressures. The only direct method for measuring BP is an invasive arterial line. Oscillometric methods estimate blood pressure. All NIBP oscillometric devices use proprietary algorithms known only to the manufacturer. The algorithms can be modified by the device manufacturer and there are no requirements for such changes to be reported. Therefore, different devices, even from the same manufacturer are not interchangeable. Philips IntelliVue monitors can be configured to be interchangeable by selecting the same reference standard algorithm on all devices.
Application Note: Non-invasive blood pressure principles
Oscillometry has become the preferred method for automated non-invasive blood pressure (NIBP) monitoring [3, 4] in most clinical settings. It is increasingly used as an alternative to the invasive blood pressure measurement. Studies show that, especially in critical cases (arrhythmia, vasoconstriction, hypertension, shock), oscillometric devices are in general more accurate and consistent than devices using other non-invasive measuring techniques. However, the oscillometric measurement method does have its limitations.
Application note: Clinical Validation of NIBP measurement
This Application Note discusses the technical developments in the Philips IntelliVue non-invasive blood pressure measurements (NIBP). This includes the choices of reference standards, and the clinical validation of measurement accuracy for available reference standards. Downloads (both application notes)
Reference standard algorithms
IntelliVue monitors offer two algorithm reference settings, Auscultatory and Invasive. Both algorithms conform to ISO 81060-2 and correspond to a traditional method of measuring blood pressure. Configuration of the NIBP reference on Philips monitors is a clinical decision that should be made by clinical leadership at the clinical facility.
Proper NIBP measurement using Philips IntelliVue patient monitors
An overview of non-invasive blood pressure measurement using Philips IntelliVue patient monitors, including measurement references, monitor configuration, pre-measurement bedside and patient setup, and measurement taking.
- When is it best to use the auscultatory instead of the invasive reference method?
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The invasive reference method is recommended if the NIBP measurement replaces or is compared to an invasive ABP measurement. The auscultatory reference method is recommended whenever the NIBP measurement replaces or is compared to manual auscultatory measurements. In general, Philips recommends to use the same reference in all care areas (OR, PACU, ICU, and so on) between which adult and pediatric patients are moved.
- Can I use a non-Philips cuff with the Philips IntelliVue patient monitors?
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Philips cannot make any claims about the performance with third-party cuffs. Our NIBP accessories and the NIBP algorithm have only been validated with the Philips cuffs.
- What do I do if there is a leak in the tubing or cuff?
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The pneumatic system must not leak. A leak in the pneumatic system might lead to an extended measurement time and could result in inaccurate readings. In case of a large leak, the NIBP pump tries to reinflate the cuff during an ongoing measurement. This might happen several times and strongly indicates a possible leak. If you notice or suspect a leak, use new tubings and cuffs. Alternatively, and if the issue persists, contact your biomedical department or your Philips representative.
- Can I use an NIBP simulator to check the measurement accuracy?
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No, you cannot use an NIBP simulator to check the measurement accuracy. You can use an NIBP simulator only to test the overall functionality of the NIBP measurement. This is because multiple factors can influence the NIBP measurement. These factors cannot be reflected by an NIBP simulator:
- Interaction between a patient’s arm and cuff.
- Manufacturers of NIBP monitors may use different algorithms. These algorithms may vary based on the monitor’s patient categories and software version.
- You can configure IntelliVue patient monitors to use different references (auscultatory or invasive).
- What happens if the NIBP algorithm cannot derive a reading?
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If the NIBP algorithm is unable to derive a reading, the algorithm will automatically initiate one or two additional measurements shortly after the first. If the additional measurements fail again, the monitor displays question marks and an INOP which informs about the unsuccessful measurement.
- What can I do if the monitor displays implausible or no readings?
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Check if one or more of the measurement limitations listed in the Instructions for Use of the monitor apply.
- What is the early systolic value?
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The NBP algorithm calculates an early systolic value during an ongoing measurement. This value is based on the previous measurement and gives a first estimate. Artifacts and changed patient conditions can impact the early systolic value. Because of this, there is no early systolic value for the first NBP measurement. If the Artifact Suppression setting is set to High, no early systolic value will be shown.
- Can I change the interval between the columns on the Vital Signs trend?
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Yes, you can have the NIBP measurement determine the interval between the columns on the Vital Signs trend. To configure this, you can select Main Setup > Trends > Setup VitalSigns > Column > NIBP. This displays the trends with one column for each NIBP measurement. Only the times and respective vital signs of an NIBP measurement are displayed.
- Why is the NIBP value on the monitor different from the mean NIBP value in my charting system?
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The mean NIBP value on the monitor is a measured value. The algorithm analyzes the oscillation envelope and computes the systolic, diastolic, and mean pressures. Some charting systems estimate the mean pressure by a rule of thumb, for example: MAP = (2 × diastolic + systolic) / 3 Such rules of thumb are less accurate because they do not consider the influence of the pulse shape and heart rates. Use the values of these charting systems with caution.
- Why do I need to discharge patients at the monitor?
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Discharging patients at the monitor resets the NIBP algorithm and removes any stored values.
- Why would I select Stop All?
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Stop All will stop all NIBP measurements when in Sequence, Auto, or STAT measurement mode. This setting will also reset the NIBP algorithm. This might help if the NIBP algorithm searches for cuff pressure oscillation in the wrong cuff pressure range because of an error in the previous reading. Make sure to restart Sequence, Auto, or STAT measurement mode if you select Stop All to reset the NIBP algorithm.
- Why is it important to select the correct patient category?
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Different patient safety limits are applied to neonatal, pediatric, and adult patients. These limits include the maximum cuff pressure and the duration of the cuff inflation. In addition, the monitor uses different algorithms based on the patient category to calculate systolic, mean, and diastolic pressures.
- Can I apply the cuff over cloth?
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No, cloth between the cuff and the patient’s arm dampens the signal. This can compromise the accuracy and availability of the NIBP measurements.
Footnotes
1. Turan A, Chang C, Cohen B, et al. Incidence, Severity, and Detection of Blood Pressure Perturbations after Abdominal Surgery: A Prospective Blinded Observational Study. Anesthesiology. 2019;130(4):550-559. doi:10.1097/ALN.0000000000002626
2. Muntner P, Shimbo D, Carey RM, et al. Measurement of Blood Pressure in Humans: A Scientific Statement From the American Heart Association. Hypertension. 2019;73(5):e35-e66. doi:10.1161/HYP.0000000000000087
3. Celler BG, Le P, Basilakis J, Ambikairajah E. Improving the quality and accuracy of non-invasive blood pressure measurement by visual inspection and automated signal processing of the Korotkoff sounds. Physiol Meas. 2017;38(6):1006-1022. doi:10.1088/1361-6579/aa6b7e
4. McLean B. Comparing blood pressure measures: does one measurement equal another?. Crit Care Nurse. 2015;35(1):75-81. doi:10.4037/ccn2015557
