Collateral circulation is important for cerebral perfusion in acute ischemic strokes. Monitoring the oxidation-reduction potential (ORP) may be useful to assess collateral status or treatment efficacy. The objectives of the present study were to determine if the ORP was associated with collateral circulation status in middle cerebral artery (MCA) occlusions and to identify patterns in the ORP and the collateral circulation status among patients treated with intraarterial therapy (IAT) over time. The present pilot study was nested within a prospective cohort study measuring the ORP of the peripheral venous plasma of stroke patients. The population included in the present study were patients with MCA (M1/M2) occlusions. Two ORP parameters were examined: Static ORP (sORP; mV), indicating oxidative stress, and capacity ORP (cORP; µC), indicating antioxidant reserves. Collateral status was retrospectively graded using Miteff's system as good (grade 1) or reduced (grade 2/3). Comparisons were made between collateral status groups (reduced vs. good collaterals) in all patients, within a subset including only patients who received IAT, and between thrombolysis in cerebral infraction scale score (TICI) groups (0-2a vs. 2b/3). The Fisher's exact test, Student's t-test and Wilcoxon tests were used (α<0.20). The 19 patients were categorized based on their collaterals: Good collaterals (53%) and reduced collaterals (47%). The baseline characteristics were similar with the exception that the patients with good collaterals had a lower international normalized ratio (P=0.12) and were more likely to have a stroke on the left side (P=0.18) or to have a mismatch (P=0.05). The admission sORP values were comparable (169.5 vs. 164.2 mV; P=0.65), as was admission cORP (P=0.73). When considering only the patients who received IAT (n=12), admission sORP (P=0.69) and cORP (P=0.90) were also statistically similar. On day 2, after IAT, both groups experienced a worsening in ORP measures; however, the patients with good collaterals had a significantly lower sORP (169.4 vs. 203.5 mV; P=0.02) and a higher cORP (0.2 vs. 0.1 µC; P=0.002) compared with the patients with reduced collaterals. Neither sORP nor cORP were significantly different between TICI score groups on admission or on day 2. Upon discharge, patients with a TICI of 2b-3 had a significantly better sORP (P=0.03) and cORP (P=0.12) compared with those with a TICI of 0-2a. In conclusion, upon patient admission, the ORP parameters were not significantly different between the collateral circulation status groups for MCA occlusions. The ORP parameters worsened after IAT regardless of the collateral circulation status; however, after IAT, on day 2, patients with good collaterals experienced less oxidative stress (sORP) and had higher antioxidant reserves (cORP) than patients with reduced collaterals.
Cerebral collateral circulation describes a network of endogenous bypass blood vessels that can provide protection in acute ischemic stroke and is important for cerebral perfusion (
The oxidation-reduction potential (ORP) in biological systems has been described as an integrated measure of the balance between total oxidants (i.e., oxidized thiols, superoxide radicals, hydroxyl radicals, hydrogen peroxide, nitric oxide, peroxynitrite and transition metal ions) and total reductants (i.e., free thiols, ascorbate, α-tocopherol, β-carotene and uric acid) (
In a previous study, the epidemiology of stroke patients was described, and plasma samples were collected for ORP analysis (
The present study aimed to utilize the ORP parameters previously measured to address the following objectives: i) determine if ORP measurements from peripheral venous plasma can identify, on admission, the collateral circulation status (good vs. reduced) of patients with MCA occlusions; ii) identify any differences in ORP measurements between collateral circulation status groups (good vs. reduced) over time across all patients and when considering only patients who received intraarterial therapy (IAT); and iii) identify if ORP measurements on admission can identify patients who had successful reperfusion among the patients who received IAT.
The present study was a pilot study nested within a previously completed prospective cohort study that measured ORP in the peripheral venous plasma of patients with stroke symptoms at a comprehensive stroke center, Swedish Medical Center (Englewood, USA) (
The initial prospective study that the present pilot study was nested within, #231797, was approved by the Hospital Corporation of America-HealthOne IRB (Englewood, USA) which is the IRB responsible for research conducted at Swedish Medical Center. Swedish Medical Center is owned by Hospital Corporation of America HealthOne, and Radiology Imaging Associates is a contracted interventional and diagnostic radiology company within Swedish Medical Center. Written informed consent for all study activities was provided by the patients or their legally authorized representative during the initial study #231797. All patients were recruited at Swedish Medical Center. The aforementioned objectives were novel ideas developed after the closure of the initial study but could be evaluated using the initial study data. Thus, a new study protocol for the present pilot study, #1562897, was submitted to Hospital Corporation of America-HealthOne IRB to use the previously collected data. The present pilot study, #1562987, which used a subset population drawn from the initial study, #231797, was reviewed by Hospital Corporation of America-HealthOne IRB and determined to be exempt from IRB approval, with a waiver of the requirement for an additional new informed consent for the present study.
Collateral grades were retrospectively assigned using admission CTAs and Miteff's system by two independent interventional radiologists (
Plasma samples were collected daily for ORP analyses until patient discharge. Plasma ORP was measured using an ultrahigh impedance electrometer (RedoxSYS® Analyzer; model number 100016; Aytu BioPharma, Inc.; rebranded under the name MiOXSYS® System;
Variables collected from the electronic medical record and from an internal database used at Swedish Medical Center to track patient admissions included: age (continuous), sex [% female (n), % male (n),], ethnicity [% White (n), % Black (n), % Hispanic (n)], time from symptom to arrival (continuous; min), initial National Institutes of Health Stroke Severity (NIHSS) score (continuous) (
Activase® Alteplase (Genentech, Inc.) was used at Swedish Medical Center for tPA treatment. The single dose was dependent on the weight of the patient per the Federal Drug Administration package label (0.09 mg/kg). Patients who arrived within 4 h of symptom onset were considered for tPA treatment with the goal of providing a single dose of tPA within the first 60 min. Administration of tPA was not recommended for patients with the following characteristics at Swedish Medical Center: ICH on CT scan, abnormal anticoagulation profile, severe head trauma within the last 3 months, posttraumatic infarction, infective endocarditis, intracranial or spinal surgery within the last 3 months, gastrointestinal (GI) malignancy, GI bleeding within the last 21 days, history of ICH, intracerebral neoplasm, CT evidence of ischemic changes, suspicion of subarachnoid hemorrhage, or aortic arch dissection.
The patient characteristics and outcomes were first compared between groups of patients based on their collateral circulation score (good collaterals vs. reduced collaterals). A subset analysis was conducted among only the patients treated with IAT, which includes catheter-based approaches to achieve recanalization using mechanical clot disruption. In the subset analysis of only patients treated with IAT, outcomes were compared between groups of patients based on the collateral circulation score (good vs. reduced collaterals). To evaluate if ORP parameters were associated with successful reperfusion, the ORP parameters were also compared between groups of patients based on their TICI score; patients with a TICI score of 0-2a (unsuccessful reperfusion) were compared with those with a TICI score of 2b, 2c or 3 (successful reperfusion).
P<0.20 was used to indicate a statistically significant difference. The present pilot study used a convenience sample drawn from a previously completed prospective study, from which 19 patients met the selection criteria. As more patients could not be obtained and the sample size was small, the P-value was increased to reduce the likelihood of a type II error (a failure to reject the null hypothesis when it was false) and increase the power (
In the present study, 19 patients were included: 53% (n=10) had good collaterals and 47% (n=9) had reduced collaterals. The mean age was 65 years, 58% of patients were female, 79% of patients were White and all patients walked independently prior to injury. The patient demographics (age, sex and ethnicity) were statistically similar between the collateral status groups (
The mean admission sORP was comparable between the groups (P=0.65), and the mean admission cORP was the same for both groups, 0.2 µC (0.1 µC) (
Among only the patients treated with IAT, the admission ORP measures were similar between the groups (
Upon admission, neither sORP nor cORP were significantly different between patients who had a TICI score of 0-2a and patients who had a TICI score of 2b-3 (
On day 1, the patients treated with tPA had a significantly lower sORP (P=0.09) and a significantly higher cORP (P=0.06) compared with the patients who were not treated with tPA (
The present pilot study found that ORP could not significantly distinguish between good and reduced collateral circulation in patients with MCA occlusions on admission, which could be due to the small sample size. However, there were associations between the ORP and collateral status when examining only the patients who were treated with IAT. The biomarker for oxidative stress (sORP) increased after IAT (change day 1 to day 2), and the biomarker for antioxidant reserves (cORP) decreased after IAT (change day 1 to day 2), indicating that IAT reopened the pathway for oxidant circulation, allowing for antioxidant consumption. Patients with reduced collaterals experienced a larger increase in oxidant circulation (sORP) from day 1 to day 2 (after IAT) and a larger decrease in antioxidant availability (cORP) from day 1 to day 2 (after IAT) compared with patients good collaterals.
In the present study, neither sORP nor cORP were able to identify good or reduced collateral circulation on admission. It has been suggested that the baseline collateral circulation status may be useful in identifying the patients who will benefit from IAT (
Alternatively, the increase in oxidative stress experienced on day 2 among the patients with reduced circulation could be the result of IAT. When considering only the patients who received IAT, there were no significant differences in the pretreatment (day 1) ORP values between the groups; however, the day 1 sORP was slightly higher among those with good collaterals. Demirbag
Among all patients, those with good collaterals appeared to have improved outcomes compared with those with reduced collaterals. The LOS among the survivors was significantly shorter for those with good collaterals compared with the patients with reduced collaterals. While not significant, the patients with good collaterals also had a lower discharge mRS and improved discharge dispositions; the patients with good collaterals were discharged home more often and died in hospital or were discharged to rehab less often than the patients with reduced collaterals. Menon
The present findings demonstrated that a higher proportion of patients with reduced collaterals who received IAT had sICH compared with patients with good collaterals. Of the patients who suffered from sICH, 100% with reduced collaterals and 50% with good collaterals died (data not shown). Semerano
In the present study, patients with good collaterals were significantly more likely to have successful recanalization defined as a TICI score of 2b, 2c or 3 compared with the patients with reduced collaterals. Similarly, Marks
In the present study, the mean admission sORP values for both groups were much higher compared with that of heathy controls in a previous study (~137 mV); similarly, the mean admission cORP was also worse for the patients in the present study compared with the mean observed in healthy controls (inverse cORP ~1.65 µV) (
The present pilot study was limited by the small sample size (n=19), especially in the analysis of only patients treated with IAT (n=12), and larger studies are required to validate the results. While samples were collected daily throughout the LOS of the patients, the LOS varied from patient to patient, thus only a small number of samples were collected after day 2. The present study was a single center study using convenience sampling, which limits the generalizability. Only patients with MCA occlusions were included as these patients underwent imaging that allowed for retrospective collateral circulation scoring. It is important to explore whether the results of the present study can be reproduced among all stroke patients. The time of plasma collection was not recorded. On admission day, there was only one collection time; a specific timepoint (e.g., 2, 4 or 6 h after admission) when the ORP can differentiate between collateral circulation status (good vs. reduced) may be found when examining ORP hourly. There is a possibility that medications can alter the ORP measurements. Because the time of plasma sample collection had not been recorded, it could not be determined if tPA treatment occurred before or after obtaining the admission sample (day 1). Future research should focus on the effect of antioxidant treatment on the outcomes of patients, especially in patients after IAT, and whether those outcomes are further improved depending on the collateral circulation status.
The ORP parameters were not able to identify the collateral circulation status for patients with MCA occlusions on admission and may not be useful in identifying the patients who may benefit from IAT. The ORP parameters worsened after IAT regardless of the collateral circulation status, but the collateral circulation status differentiated the degree of posttreatment oxidative insult (sORP). Patients with reduced collateral circulation experienced a larger increase in oxidative stress (sORP) after IAT, potentially due to the lack of good collateral circulation around the ischemia leading to a sequestering of oxidants pretreatment. After IAT, patients with good collateral circulation continued to experience less oxidative stress (sORP) and had higher antioxidant reserves (cORP) compared with the patients with reduced collateral circulation; this was also the case on the last collection day.
The authors would like to thank the IRB coordinator at Injury Outcomes Network (Englewood, USA), Ms. Tina Thompson, who assisted with IRB submissions and documentation. The authors would like to thank the clinical research coordinator at Injury Outcomes Network (Englewood, USA), Ms. Breanna Nickels, and the nurse practitioners at Swedish Medical Center (Englewood, USA), Ms. Amy Nieberlein and Ms. Jasmin Johann, who all assisted with the data collection for this project.
The datasets generated and/or analyzed during the current study are not publicly available due to data use agreements with the participating hospital but are available from the corresponding author on reasonable request.
BA, SJ, RB, TB, LD, KS, RBO and DBO contributed to the study design. DBO and RBO contributed to the study conception. SJ and DBO confirm the authenticity of all the raw data. TB, LD, BA and RB contributed to the data collection. SJ conducted the statistical analysis. KS reviewed the statistical analysis. SJ drafted the original manuscript. All authors have read and approved the final manuscript.
The pilot study was deemed exempt from IRB approval by the Hospital Corporation of America-HealthOne IRB, Englewood, USA (#1562897). The requirement of patient consent for participation was also waived by the Hospital Corporation of America-HealthOne IRB.
Not applicable.
The authors declare that they have no competing interests.
Clinical characteristics.
Patient characteristics | Good collaterals (n=10) | Reduced collaterals (n=9) | P-value |
---|---|---|---|
Age, years [mean (SD)] | 62.7 (24.1) | 66.7 (11.7) | 0.66 |
Sex, % (n) | >0.99 | ||
Female | 60(6) | 56(5) | |
Male | 40(4) | 44(4) | |
Ethnicity, % (n) | >0.99 | ||
White | 90(9) | 89(8) | |
Black | 10(1) | 0 (0) | |
Hispanic | 0 (0) | 11(1) | |
Walking independently, % (n) | 100(10) | 100(9) | N/A |
Symptom to arrival, min [mean (SD)] | 197.1 (142.5) | 230.6 (109.9) | 0.59 |
Initial NIHSS score [mean (SD)] | 18.3 (5.2) | 15.9 (6.7) | 0.39 |
Creatinine, mg/dl [mean (SD)] | 1.0 (0.2) | 1.1 (0.3) | 0.58 |
LDL, mg/dl [mean (SD)] | 88.0 (36.4) | 88.3 (34.7) | 0.98 |
INR [mean (SD)] | 1.0 (0.1) | 1.1 (0.1) | 0.12 |
Admission type, % (n) | 0.35 | ||
Transferred | 50(5) | 78(7) | |
Direct Admission | 50(5) | 22(2) | |
Side of stroke, % (n) | 0.18 | ||
Left | 70(7) | 33(3) | |
Right | 30(3) | 67(6) | |
Mismatch, % (n) | 0.05 | ||
Yes | 60(6) | 11(1) | |
No | 40(4) | 89(8) | |
Treatment, % (n) | 0.29 | ||
Both IAT and tPA | 50(5) | 33(3) | |
Only IAT | 20(2) | 22(2) | |
Only tPA | 20(2) | 0 (0) | |
Neither IAT nor tPA | 10(1) | 44(4) |
Data presented as the mean (SD) were compared using an unpaired Student's t-test, and dichotomous and categorical data were compared with Fisher's exact test. NIHSS, National Institutes of Health Stroke Severity; LDL, low-density lipoproteins; INR, international normalized ratio; IAT, intraarterial therapy; tPA, tissue plasminogen activator.
ORP values over time by collateral grade.
Outcome | Good collaterals (n=10) | Reduced collaterals (n=9) | P-value |
---|---|---|---|
Type and day of ORP sample collection | |||
Day 1 | |||
sORP, mV [mean (SD)] | 169.5 (28.4) | 164.2 (18.9) | 0.65 |
cORP, µV [mean (SD)] | 0.2 (0.1) | 0.2 (0.1) | 0.73 |
Day 2 | |||
sORP, mV [mean (SD)] | 168.6 (14.6) | 188.7 (28.6) | 0.07 |
cORP, µV [mean (SD)] | 0.2 (0.0) | 0.2 (0.1) | 0.20 |
Change between day 1 and 2 | |||
sORP, mV [median (IQR)] | 5.8 (-20.3, 14.2) | 4.1 (-2.7, 40.2) | 0.48 |
cORP, µV [median (IQR)] | 0.0 (-0.1, 0.0) | 0.0 (-0.1, 0.0) | 0.96 |
Last collected sample | |||
sORP, mV [mean (SD)] | 160.1 (11.5) | 167.7 (26.3) | 0.46 |
cORP, µV [mean (SD)] | 0.3 (0.1) | 0.3 (0.2) | 0.52 |
Last collection day, days [mean (SD)] | 6.0 (4.0) | 6.0 (4.0) | 0.97 |
Discharge mRS [median (IQR)] | 3.0 (2.0, 4.0) | 4.0 (3.0, 4.0) | 0.31 |
LOS, days [mean (SD)] | |||
Among all patients | 7.2 (3.0) | 8.4 (7.0) | 0.63 |
Among survivors | 7.0 (3.1) | 9.4 (7.5) | 0.03 |
Discharge disposition, % (n) | 0.34 | ||
Death or hospice | 10.0(1) | 33.3(3) | |
Home or home with healthcare services | 40.0(4) | 11.1(1) | |
Rehabilitation | 50.0(5) | 55.6(5) |
Data presented as the median (IQR) were compared using the Wilcoxon rank sum test, data presented as the mean (SD) were compared using an unpaired Student's t-test, and dichotomous and categorical data were compared with Fisher's exact test. ORP, oxidation-reduction potential; sORP, static ORP; cORP, capacity ORP; mRS, modified Rankin Scale; LOS, length of stay; IQR, interquartile range.
Outcomes of patients treated with IAT.
Outcome | Good collaterals (n=7) | Reduced collaterals (n=5) | P-value |
---|---|---|---|
Type and day of ORP sample collection | |||
Day 1 | |||
sORP, mV [mean (SD)] | 162.9 (26.9) | 156.3 (19.2) | 0.69 |
cORP, µV [mean (SD)] | 0.2 (0.1) | 0.2 (0.1) | 0.90 |
Day 2 | |||
sORP, mV [mean (SD)] | 169.4 (16.6) | 203.5 (26.1) | 0.02 |
cORP, µV [mean (SD)] | 0.2 (<0.1) | 0.1 (<0.1) | <0.01 |
Change between day 1 and 2 | |||
sORP, mV [median (IQR)] | 13.0 (0.2, 24.2) | 40.2 (16.7, 68.2) | 0.13 |
cORP, µV [median (IQR)] | -0.1 (-0.1, <0.1) | -0.1 (-0.1, <-0.1) | 0.18 |
Last collected sample | |||
sORP, mV [mean (SD)] | 156.7 (10.5) | 181.4 (22.8) | 0.03 |
cORP, µV [mean (SD)] | 0.3 (0.1) | 0.2 (0.1) | 0.01 |
Average after IAT | |||
sORP, mV [mean (SD)] | 161.4 (8.8) | 184.8 (25.5) | 0.04 |
cORP, µV [mean (SD)] | 0.3 (<0.1) | 0.2 (0.1) | 0.03 |
Treatment, % (n) | >0.99 | ||
Both IAT and tPA | 71.4(5) | 60.0(3) | |
tPA only | 0.0 (0) | 0.0 (0) | |
IAT only | 29.6(2) | 40.0(2) | |
Neither IAT nor tPA | 0.0 (0) | 0.0 (0) | |
Time from stroke alert to IAT, min [mean (SD)] | 95.9 (27.8) | 85.0 (41.0) | 0.61 |
TICI score, % (n) | 0.18 | ||
2b, 2c or 3 | 100.0(7) | 60.0(3) | |
0, 1 or 2a | 0.0 (0) | 40.0(2) | |
sICH, % (n) | >0.99 | ||
Yes | 29.0(2) | 40.0(2) | |
No | 71.4(5) | 60.0(3) | |
LOS, days [median (IQR)] |
|||
Among all patients | 7.0 (5.0, 11.0) | 3.0 (2.0, 9.0) | 0.33 |
Among survivors | 6.5 (5.0, 11.0) | 3.0 (2.0, 19.0) | 0.44 |
Discharge mRS [median (IQR)] | 3.2 (1.6) | 4.4 (1.7) | 0.27 |
Discharge disposition, % (n) | 0.34 | ||
Death or hospice | 14.3(1) | 60(3) | |
Home or home with healthcare services | 28.9(2) | 20(1) | |
Rehabilitation | 57.4(4) | 20(1) |
aLOS was non-parametric among the patients treated with IAT, therefore the median (IQR) is presented and compared. Data presented as the median (IQR) were compared with the Wilcoxon rank sum test, data presented as the mean (SD) were compared using an unpaired Student's t-test, and dichotomous and categorical data were compared with Fisher's exact test. sORP, static oxidation-reduction potential; cORP, capacity oxidation-reduction potential; mRS, modified Rankin Scale; sICH, symptomatic intracranial hemorrhage; LOS, length of stay; IQR, interquartile range; IAT, intraarterial therapy; tPA, tissue plasminogen activator; TICI, thrombolysis in cerebral infarction scale.
ORP measurements over time compared between TICI score groups.
Type and day of ORP sample collection | TICI 0-2a | TICI 2b, 2c and 3 | P-value |
---|---|---|---|
Day 1 | |||
sORP, mV [median (IQR)] | 160.7 (142.0, 178.5) | 164.0 (138.1, 190.6) | >0.99 |
cORP, µV [median (IQR)] | 0.2 (0.2, 0.3) | 0.2 (0.2, 0.3) | >0.99 |
Day 2 | |||
sORP, mV [median (IQR)] | 200.9 (189.0, 212.8) | 176.9 (166.6, 197.0) | 0.35 |
cORP, µV [median (IQR)] | 0.2 (0.1, 0.2) | 0.2 (0.2, 0.2) | 0.34 |
Change between day 1 and 2 | |||
sORP, mV [median (IQR)] | 40.2 (34.3, 46.1) | 13.6 (-10.7, 27.9) | 0.11 |
cORP, µV [median (IQR)] | -0.1, (-0.1, 0.0) | -0.1 (-0.1, 0.0) | 0.79 |
Last collected | |||
sORP, mV [median (IQR)] | 200.9 (189.0, 212.8) | 156.6 (153.8, 165.7) | 0.03 |
cORP, µV [median (IQR)] | 0.2 (0.1, 0.2) | 0.3 (0.2, 0.4) | 0.12 |
Data presented as the median (IQR) were compared with the Wilcoxon rank sum test. ORP, oxidation-reduction potential; sORP, static ORP; cORP, capacity ORP; TICI, thrombolysis in cerebral infarction scale; IQR, interquartile range.