Predictive Values for Time from Transducer Stopcock Closure to Accurate Intracranial Pressure Reading.

BACKGROUND: When using an external ventricular drain (EVD) to monitor intracranial pressure (ICP), nurses need to know how long to wait after each manipulation of the transducer before the displayed ICP value represents an accurate signal. This study explores ICP signal equilibration time (EqT) under clinical conditions. METHODS: This was a prospective ex vivo study using a simulated skull, standard EVD tubing, and a strain gauge transducer. All 270 trials simulating 90 combinations of different pressures and common clinical conditions were completed in August 2021. Each trial was recorded on video. Videos were scored using video editing software to obtain the exact start and stop time for each trial. RESULTS: The mean EqT was 44.90 (18.77) seconds. One hundred fifty (55.56%) observations did not reach their expected value within 60 s. The longest mean EqTs were noted when blood was present in the EVD tubing (57.67 [8.91] seconds), when air bubbles were in the tubing (57.41 [8.73] seconds), and when EVD tubing was not flat (level) (50.77 [15.43] seconds). An omnibus test comparing mean EqT for conditions with no variables manipulated (30.08 [16.07] seconds) against mean EqT for all others (47.18 [18.13] seconds) found that mean EqTs were significantly different (P < 0.001). CONCLUSIONS: Even when no additional variables were introduced, the mean EqTs were ~ 30 s. Common clinical variables increase the length of time before a transducer connected to an EVD will provide an accurate reading. Nurses should wait at least 30 s after turning the EVD stopcock before assuming ICP value reflects accurate ICP.

Exploring the accuracy and precision of BP measurements.

ABSTRACT: Accurate and precise BP measurements are crucial to clinical decision-making and interventions as healthcare professionals aim to prevent complications from hypertension, yet the literature provides no gold standard for measuring BP. This article discusses the additional research necessary to develop best practices and improve patient outcomes.

Neurological Pupil Index as an Indicator of Irreversible Cerebral Edema: A Case Series.

ABSTRACT: BACKGROUND: Assessing the pupillary light reflex is a core component of neurological assessments. Pupil size and reactivity can provide early warning about early neurological decline. Automated infrared pupillometry is noninvasive and easy to use and has greater reliability compared with manual assessments to obtain objective and consistent measurements of pupillary size and reactivity to light. METHODS: This is a case series of 3 patients who had poor baseline clinical neurological examinations. Because it would be more difficult to detect acute neurological deterioration, automated infrared pupillometry and the Neurological Pupil index (NPi) were used in addition to the clinical neurological examination. NPi values < 3.0 prompted further imaging. RESULTS: In each case, abnormal NPi values prompted emergent imaging that confirmed acute cerebral edema and resulted in a change in management and treatment plan. CONCLUSION: The automated infrared pupillometry is a noninvasive monitor that can provide additional objective data in patients with a poor baseline neurological examination in whom it may otherwise be difficult to detect neurological deterioration.

Blood Pressure measurements are site dependent in a cohort of patients with neurological illness.

Blood pressure (BP) management is a crucial part of critical care that directly affects morbidity and mortality. While BP has become a mainstay in patient care, the accuracy and precision of BP measures across commonly used sites (left upper arm, right upper arm, etc.) and methods have not been established. This study begins to fill this gap in literature by testing the null hypothesis that BP measurement does not vary according to site. This is a prospective, non-randomized, cross-sectional study of 80 neurocritical care unit patients. Near simultaneous non-invasive blood pressure (NIBP) readings from 4 different locations (bilateral upper arm, bilateral wrist) and, when available, intra-arterial blood pressure readings (IABP) were included. Pearson correlation coefficients and one-way repeated measures ANOVA were used to observe the systolic, diastolic, and mean arterial pressure (MAP) correlations. The BP measured at the four most common sites (left upper arm, left wrist, right upper arm, right wrist) had adequate correlation coefficients but were statistically significantly different and highly unpredictable. The median inter-site systolic variability was 10 mmHg (IQR 2 to 10 mmHg). The median inter-site MAP variability was 6mmHg with an interquartile range (IQR) of 3 to 9 mmHg. As expected, the values correlated to show that patients with high BP in one site tended to have high BP in another site. However, the unpredictable inter-site variability is concerning within the clinical setting where oftentimes BP measurement site is not standardized but resulting values are nevertheless used for treatment. There is prominent inter-site variability of BP measured across the 4 most common measurement sites. The variability persists across non-invasive (NIBP) and invasive (IABP) methods of assessment.