Prehospital stroke triage: a modeling study on the impact of triage tools in different regions

BACKGROUND AND PURPOSE

Direct transportation to a thrombectomy-capable intervention center is beneficial for patients with ischemic stroke due to large vessel occlusion (LVO), but can delay intravenous thrombolytics (IVT). The aim of this modeling study was to estimate the effect of prehospital triage strategies on treatment delays and overtriage in different regions.

METHODS

We used data from two prospective cohort studies in the Netherlands: the Leiden Prehospital Stroke Study and the PRESTO study. We included stroke code patients within 6 hours from symptom onset. We modeled outcomes of RACE triage and triage with a personalized decision tool, using drip-and-ship as reference. Main outcomes were overtriage (stroke code patients incorrectly triaged to an intervention center), reduced delay to endovascular thrombectomy (EVT), and delay to IVT.

RESULTS

We included 1798 stroke code patients from four ambulance regions. Per region, overtriage ranged from 1-13% (RACE triage) and 3-15% (personalized tool). Reduction of delay to EVT varied by region between 24 ± 5 minutes (n = 6) to 78 ± 3 (n = 2), while IVT delay increased with 5 (n = 5) to 15 minutes (n = 21) for non-LVO patients. The personalized tool reduced delay to EVT for more patients (25 ± 4 minutes (n = 8) to 49 ± 13 (n = 5)), while delaying IVT with 3-14 minutes (8-24 patients). In region C, most EVT patients were treated faster (reduction of delay to EVT 31 ± 6 minutes (n = 35), with RACE triage and the personalized tool.

CONCLUSIONS

In this modeling study, we showed that prehospital triage reduced time to EVT without disproportionate IVT delay, compared to a drip-and-ship strategy. The effect of triage strategies and the associated overtriage varied between regions. Implementation of prehospital triage should therefore be considered on a regional level.

Accuracy of CTA evaluations in daily clinical practice for large and medium vessel occlusion detection in suspected stroke patients

INTRODUCTION

Early detection of large vessel occlusion (LVO) is essential to facilitate fast endovascular treatment. CT angiography (CTA) is used to detect LVO in suspected stroke patients. We aimed to assess the accuracy of CTA evaluations in daily clinical practice in a large cohort of suspected stroke patients.

PATIENTS AND METHODS

We used data from the PRESTO study, a multicenter prospective observational cohort study that included suspected stroke patients between August 2018 and September 2019. Baseline CTAs were re-evaluated by an imaging core laboratory and compared to the local assessment. LVO was defined as an occlusion of the intracranial internal carotid artery, M1 segment, or basilar artery. Medium vessel occlusion (MeVO) was defined as an A1, A2, or M2 occlusion. We calculated the accuracy, sensitivity, and specificity to detect LVO and LVO+MeVO, using the core laboratory evaluation as reference standard.

RESULTS

We included 656 patients. The core laboratory detected 89 LVOs and 74 MeVOs in 155 patients. Local observers missed 6 LVOs (7%) and 28 MeVOs (38%), of which 23 M2 occlusions. Accuracy of LVO detection was 99% (95% CI: 98-100%), sensitivity 93% (95% CI: 86-97%), and specificity 100% (95% CI: 99-100%). Accuracy of LVO+MeVO detection was 95% (95% CI: 93-96%), sensitivity 79% (95% CI: 72-85%), and specificity 99% (95% CI: 98-100%).

DISCUSSION AND CONCLUSION

CTA evaluations in daily clinical practice are highly accurate and LVOs are adequately recognized. The detection of MeVOs seems more challenging. The evolving EVT possibilities emphasize the need to improve CTA evaluations in the acute setting.

Validity of prediction of the site of ruptured intracranial aneurysms with CT

OBJECTIVE

We studied the diagnostic power of blood distribution on CT (performed within 72 hours after the bleed) for the site of ruptured aneurysm in 168 consecutive patients with subarachnoid hemorrhage with either a single aneurysm or no aneurysm on the four-vessel angiogram or postmortem examination.

METHODS

A neurosurgeon and a neuroradiologist blind to the results of the angiography independently scored the distribution of blood on the CT and predicted the site of the ruptured aneurysm.

RESULTS

Overall agreement among raters was 52% and chance-adjusted agreement (kappa) was 0.42 (weighted kappa value 0.47). A parenchymal cerebral hematoma was an excellent predictor for the site of a ruptured aneurysm but was present in only a minority of cases (15%). The next most valid predictor was blood distribution on CT in patients with a ruptured anterior cerebral artery aneurysm or anterior communicating artery aneurysm (sensitivity 0.79, specificity 0.96, and positive predictive value 0.79 for rater 1; sensitivity 0.77, specificity 0.97, and positive predictive value 0.90 for rater 2). The validity of the predictive value of blood distribution on CT in patients with a ruptured aneurysm of the middle cerebral artery, internal carotid artery, or posterior circulation arteries was either inconsistent between raters or low.

CONCLUSION

With the exception of the presence of a parenchymal hematoma, the site of the ruptured aneurysm can be predicted by CT only in ruptured anterior cerebral artery or anterior communicating artery aneurysms.

Impact of medical treatment on the outcome of patients after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The rationale behind early aneurysm surgery in patients with subarachnoid hemorrhage (SAH) is the prevention of rebleeding as early as possible after SAH. In addition, by clipping the aneurysm as early as possible, one can apply treatment for cerebral ischemia more vigorously (induced hypertension) without the risk of rebleeding. Hypervolemic hemodilution is now a well-accepted treatment for delayed cerebral ischemia. We compared the prospectively collected clinical data and outcome of patients admitted to the intensive care unit in the period 1977 to 1982 with those of patients admitted in the period 1989 to 1992 to measure the effect of the change in medical management procedures on patients admitted in our hospital with SAH.

METHODS

We studied 348 patients admitted within 72 hours after aneurysmal SAH. Patients with negative angiography results and those in whom death appeared imminent on admission were excluded. The first group (group A) consisted of 176 consecutive patients admitted from 1977 through 1982. Maximum daily fluid intake was 1.5 to 2 L. Hyponatremia was treated with fluid restriction (<1 L/24 h). Antihypertensive treatment with diuretic agents was given if diastolic blood pressure was >110 mm Hg. Patients in the second group (172 consecutive patients; group B) were admitted from 1989 through 1992. Daily fluid intake was at least 3 L, unless cardiac failure occurred. Diuretic agents and antihypertensive medications were avoided. Cerebral ischemia was treated with vigorous plasma volume expansion under intermittent monitoring of pulmonary wedge pressure, cardiac output, and arterial blood pressure, aiming for a hematocrit of 0.29 to 0.33. Aneurysm surgery was planned for day 12.

RESULTS

Patients admitted in group B had less favorable characteristics for the development of cerebral ischemia and for good outcome when compared with patients in group A. Despite this, we found a significant decrease in the frequency of delayed cerebral ischemia in patients of group B treated with tranexamic acid (P=0.00005 by log rank test) and significantly improved outcomes among patients with delayed cerebral ischemia (P=0.006 by chi2 test) and among patients with deterioration from hydrocephalus (P=0.001 by chi2 test). This resulted in a significant improvement of the overall outcome of patients in group B when compared with those in group A (P=0.006 by chi2 test). The major cause of death in group B was rebleeding (P=0.011 by chi2 test).

CONCLUSIONS

We conclude that the outcome in our patients with aneurysmal SAH was improved but that rebleeding remains a major cause of death. Patient outcome can be further improved if we can increase the efficacy of preventive measures against rebleeding by performing early aneurysm surgery.

Predictive factors for deterioration from hydrocephalus after subarachnoid hemorrhage

We studied the predictive factors for deterioration from hydrocephalus that developed during the first 28 days after admission in 660 patients following aneurysmal subarachnoid hemorrhage (SAH). Deterioration from hydrocephalus was defined as deterioration of consciousness with no detectable cause other than hydrocephalus confirmed by a repeat CT with a bicaudate index exceeding the 95th percentile for age. Deterioration from hydrocephalus occurred in 143 (22%) of the 660 patients. The variables included in the analysis were sex, age, loss of consciousness at ictus, sum score on the Glasgow Coma Scale on admission, sum score of cisternal blood and presence of ventricular blood on initial CT, hydrocephalus on initial CT, confirmed aneurysm, rebleeding, delayed cerebral ischemia, and treatment with tranexamic acid for 4 (short-term treatment) or 28 (long-term treatment) days. In a multivariate analysis with the Cox proportional hazards model incorporating fixed and time-dependent covariates, sum score of cisternal blood on initial CT (hazard ratio 3.15, p < 0.000001), presence of ventricular blood on initial CT (hazard ratio 1.66, p = 0.004), hydrocephalus on initial CT (hazard ratio 3.37, p < 0.000001), and long-term treatment with tranexamic acid (hazard ratio 2.40, p < 0.000001) were significantly related with the development of hydrocephalus. We conclude that a high amount of blood after SAH and delay of the resorption of cisternal and ventricular blood caused by long-term treatment with tranexamic acid increases the risk of deterioration from hydrocephalus after SAH.