Abstract
Although intravenous administration of contrast media may trigger a variety of adverse reactions, sedated patients undergoing computed tomography (CT) scanning usually are not able to report their symptoms, which may delay detection of adverse reactions. Furthermore, changes in vital signs cannot be typically measured during mobile CT scanning, which worsens the situation. We aimed to characterize contrast-related hemodynamic changes that occur during mobile CT scanning and predict sudden hypotension based on subtle but robust changes in the electrocardiogram (ECG). We analyzed the digitized hemodynamic data of 20 consecutive patients who underwent clipping of a cerebral artery aneurysm and contrast-enhanced CT scanning following the surgical procedure. Hemodynamic variables, including ECG findings, invasive blood pressure (BP), pulse oximetry results, capnography findings, cardiac output, and systemic vascular resistance, were monitored simultaneously. We measured morphological changes in ECG-derived parameters, including the R–R interval, ST height, and QRS R-amplitude, on a beat-to-beat basis, and evaluated the correlation between those parameters and hemodynamic changes. After the radiocontrast injection, systolic BP decreased by a median 53 mmHg from baseline and spontaneously recovered after 63 ± 19 s. An increase in QRS R-amplitude (median 0.43 mV) occurred 25 ± 10 s before hypotension developed. The receiver operating characteristic curve showed that a 16% increase in QRS R-amplitude can predict a decrease in systolic BP of >25% (area under the curve 0.852). Increased cardiac output (median delta 2.7 L/min from baseline) and decreased systemic vascular resistance (median delta 857 dyn·s/cm5 from baseline) were also observed during hypotension. During mobile CT scanning, profound but transient hypotension can be observed, associated with decreased vascular resistance. Augmentation of QRS R-amplitude from an ECG represents a sensitive surrogate for onset of a hypotensive episode after contrast injection, thereby serving as a simple and continuous noninvasive hemodynamic monitoring tool.
Highlights
The intravenous administration of contrast media may trigger various kinds of adverse reactions such as nausea, dizziness, urticaria, and profound hypotension within minutes after administration [1,2]
We present the use of subtle changes in the electrocardiogram (ECG) as a noninvasive but robust index to predict hemodynamic changes
Augmentation of the QRS R-amplitude by 16% was observed 25.2 s earlier than the development of profound hypotension (25% decrease in systolic BP (SBP)). This finding implies that morphologic changes in the ECG can be useful in detecting the onset of profound hypotension when invasive blood pressure (BP) monitoring is not feasible
Summary
The intravenous administration of contrast media may trigger various kinds of adverse reactions such as nausea, dizziness, urticaria, and profound hypotension within minutes after administration [1,2]. Given the circumstances that the hemodynamic effect of contrast injection is transitory and usually followed by immediate recovery within 3-4 minutes [7,8], it is possible that unrecognized hypotension may have occurred under noninvasive blood pressure (BP) monitoring. Continuous monitoring is not generally performed as most patients have a short exposure duration to the contrast agent, which increases the possibilities of under-detection. If patients are incapable of reporting their own symptoms, such as sedated patients undergoing CT scanning, it would more difficult to recognize the onset of an adverse event. Most symptoms may be mild and transitory and recover without any complications, potentially life-threatening adverse events still occur. The important part of monitoring is that the attending physician should be able to detect any symptoms or signs in a timely manner, which could assist in early recognition and treatment [9]
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