Circulation 122,210 • Volume 34, No. 1 • June 2019   Issue PDF

Monitoring Gaps

Sheron McLean, MD

Dear Rapid Response:

The American Society of Anesthesiologists standards for basic anesthetic monitoring require that all patients receiving an anesthetic have arterial blood pressure monitored, at a minimum frequency of once every five minutes, except under extenuating circumstances.1 Monitoring gaps may occur for various reasons including patient positioning or pausing the automatic cycle for placement of an arterial line. When this occurs, the anesthesia professional sometimes fails to re-engage the monitor to return to periodic measurements, which can lead to extended monitoring gaps. In addition to this human issue, there is a system issue. The design features of some patient monitors, including the General Electric (GE) CARESCAPE B-850, which we use in many of our operating rooms at Michigan Medicine, will display the last measured blood pressure without providing an audible or visual alert if this measurement is not current. This may lead to a false impression that blood pressure is being measured, when in fact the blood pressure displayed is an older measurement. This is in contrast to a detached ECG cable or temperature cable that results in audible alarms. Additionally, a poorly attached cuff or faulty cuff may continue to cycle in an attempt to attain a blood pressure reading without an alert. This can lead to monitoring gaps and potentially compromise patient safety. At Michigan Medicine, we have a system that is designed to integrate with patient monitoring devices and provide alerts for actual and potential issues. This system will alert a provider to a monitoring gap; however, the application needs to be open and running in the operating room and will provide a single beep to alert the anesthesia professional at the six-minute mark if a blood pressure reading is not obtained. It seems as though there should be a simple software solution to this monitoring issue on the GE models that would provide for an alert when a new blood pressure reading is not obtained shortly after five minutes. While this will certainly not eliminate the problem of monitoring gaps, it may help to better identify an issue that can easily be remedied.

Sheron McLean, MD

Dr. McLean is clinical assistant professor in the Department of Anesthesiology at Michigan Medicine, Ann Arbor, MI.

Dr. McLean has no conflicts of interest pertaining to this article.


  1. American Society of Anesthesiologists. Standards for basic monitoring (1986). Accessed March 2, 2019.



Thank you for highlighting the challenges of non-invasive blood pressure measurements and display within the operating room. When designing a patient monitor, GE Healthcare seeks to support the latest industry standards and trends for delivering care. The design process also includes patient and clinician feedback regarding the reliability and usability of our devices.

The CARESCAPE line of patient monitors, including the CARESCAPE B850 patient monitor, is designed to be used in multiple care areas. GE Healthcare recognizes different care areas utilize the monitor features in different ways, and there can also be different use cases within a single care area. The CARESCAPE monitoring platform has therefore been designed to be flexible, enabling clinicians to configure the monitor to best support the patient needs.

The non-invasive blood pressure (NIBP) display option is one of those flexible features that can be configured to a specific need. As an example, neonatal intensive care unit patients generally do not require frequent NIBP measurements; therefore, CARESCAPE monitor software can be configured for the NIBP measurement to display the last measured value for up to four hours although the value will become “greyed-out” after sixty minutes (Figure 1). In contrast, operating room patients require more frequent NIBP measurements, and for this reason the CARESCAPE software can be configured for the NIBP measurement to automatically cycle every five minutes (Figure 2), and the measured value will no longer be displayed after 5 minutes (Figure 3).

NIBP display with "normal" white text.

NIBP display with “normal” white text.

NIBP display with "greyed-out" white text.<br><br>Figure 1: Example NIBP display text showing color change once the NIBP value becomes aged—e.g., 30 or 60 minutes depending on monitor configuration.

NIBP display with “greyed-out” white text.

Figure 1: Example NIBP display text showing color change once the NIBP value becomes aged—e.g., 30 or 60 minutes depending on monitor configuration.

To turn on automatic NIBP cycling, users can select the NIBP window (Figure 2, Step 1) to open the Non-Invasive Blood Pressure setup window. From the setup window, users may select the appropriate cycle time using the dropdown menu (Figure 2, Step 2); cycle time intervals include minute intervals of 1, 2, 2.5, 3, 4, 5, 10, 15, 20, and 30 and hour intervals of 1, 2, or 4. Once the Cycle Time is selected, users can turn on the NIBP Auto function by selecting Start Cycling (Figure 2, Step 3).

Figure 2: "General Electric (GE) CARESCAPE B-850" NIBP automatic cycle configuration.

Figure 2: “General Electric (GE) CARESCAPE B-850” NIBP automatic cycle configuration.

When configuring the monitor defaults, under Care Unit Settings > Parameters, there is an option to select the NIBP Display Timeout duration. Selecting a duration of “5min” (Figure 4) will result in the NIBP value being removed and replaced with dashed lines (Figure 3) five minutes after the last NIBP value is obtained. Other options for the NIBP Display Timeout include 30min/1hr and 60min/4hr and depending on the selection, the last reading will be displayed for one or four hours, with the reading becoming “greyed-out” after either thirty or sixty minutes (Figure 1).

Figure 3: This figure depicts the NIBP display after timeout.

Figure 3: This figure depicts the NIBP display after timeout.

Figure 4: NIBP Display Timeout selection.

Figure 4: NIBP Display Timeout selection.

Another feature to help clinicians recognize when an NIBP reading was last obtained is the numerical display. If the NIBP Cycle Time Display is configured for Numerical display (this configuration is located under Monitor Setup > Care Unit Settings > Parameters), the specific time of the last NIBP measurement is displayed at the bottom right of the NIBP parameter window (Figure 5). This timestamp will be present for both manual and automatic NIBP readings. If the NIBP Auto Cycle is turned on, there will also be a countdown until the next NIBP measurement is scheduled (Figure 5).

Figure 5: NIBP time stamp and countdown until next cycle.

Figure 5: NIBP time stamp and countdown until next cycle.

If the monitor is attempting to take an NIBP reading, the cuff pressure is displayed on the right side of the parameter window as a visual indicator that a reading is being attempted. If the systolic and diastolic values are removed and the cuff pressure reads “0,” this indicates the monitor was unable to obtain a blood pressure measurement. When operating the monitor in the NIBP Auto mode, the monitor will then automatically attempt to capture another NIBP measurement at the next set measurement interval; however, if the underlying condition preventing the capture of the blood pressure persists, the automatic measurement mode will deactivate and the numeric value will remain blank, showing dashes instead of a measurement value. If there is a technical reason for the inability to measure the blood pressure, such as a loose cuff, the monitor will provide an audible alarm along with a message intended to help identify the source of the technical alarm.

Please consult the CARESCAPE monitor’s operator’s manual or contact GE Healthcare for additional information on the available setting configurations for blood pressure measurements.

Cory Stahl

Cory Stahl is the global marketing manager for GE Healthcare’s patient monitoring business, Milwaukee, WI.

The information provided is for safety-related educational purposes only, and does not constitute medical or legal advice. Individual or group responses are only commentary, provided for purposes of education or discussion, and are neither statements of advice nor the opinions of APSF. It is not the intention of APSF to provide specific medical or legal advice or to endorse any specific views or recommendations in response to the inquiries posted. In no event shall APSF be responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the reliance on any such information.

Editorial Commentary:

The Challenges of Designing Monitoring Displays and Alerts
Jeffrey Feldman, MD, MSE

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