The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury
Abstract Background Cerebral regional microcirculation is altered following severe head injury. In addition to tissue disruption, partial pressure of tissue oxygenation is impaired due to an increase in the oxygen tissue gradient. The heterogenic distribution of cerebral microcirculation is multifac...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-11-01
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| Series: | Intensive Care Medicine Experimental |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s40635-018-0210-5 |
| _version_ | 1818117158966657024 |
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| author | Judith Bellapart Kylie Cuthbertson Kimble Dunster Sara Diab David G. Platts Christopher Raffel Levon Gabrielian Adrian Barnett Jennifer Paratz Rob Boots John F. Fraser |
| author_facet | Judith Bellapart Kylie Cuthbertson Kimble Dunster Sara Diab David G. Platts Christopher Raffel Levon Gabrielian Adrian Barnett Jennifer Paratz Rob Boots John F. Fraser |
| author_sort | Judith Bellapart |
| collection | DOAJ |
| description | Abstract Background Cerebral regional microcirculation is altered following severe head injury. In addition to tissue disruption, partial pressure of tissue oxygenation is impaired due to an increase in the oxygen tissue gradient. The heterogenic distribution of cerebral microcirculation is multifactorial, and acute anemia challenges further the delivery of oxygen to tissues. Currently, a restrictive transfusion threshold is globally applied; however, it is unclear how anemia modifies regional cerebral microcirculation; hence, it is unclear if by aiming to a global endpoint, specific anatomical regions undergo ischemia. This study aims to quantify the temporal changes in cerebral microcirculation after severe head injury, under the effect of anemia and transfusion. It also aims to assess its effects specifically at the ischemic penumbra compared to contralateral regions and its interactions with axonal integrity in real time. Twelve ovine models were subjected to a severe contusion and acceleration-deceleration injury. Normovolemic anemia to a restrictive threshold was maintained after injury, followed by autologous transfusion. Direct quantification of cerebral microcirculation used cytometric count of color-coded microspheres. Axonal injury was assessed using amyloid precursor protein staining. Results A mixed-effect regression model from pre-transfusion to post-transfusion times with a random intercept for each sheep was used. Cerebral microcirculation amongst subjects with normal intracranial pressure was maintained from baseline and increased further after transfusion. Subjects with high intracranial pressure had a consistent reduction of their microcirculation to ischemic thresholds (20–30 ml/100 g/min) without an improvement after transfusion. Cerebral PtiO2 was reduced when exposed to anemia but increased in a 9.6-fold with transfusion 95% CI 5.6 to 13.6 (p value < 0.001). Conclusions After severe head injury, the exposure to normovolemic anemia to a restrictive transfusion threshold, leads to a consistent reduction on cerebral microcirculation below ischemic thresholds, independent of cerebral perfusion pressure. Amongst subjects with raised intracranial pressure, microcirculation does not improve after transfusion. Cerebral oxymetry is impaired during anemia with a statistically significant increase after transfusion. Current transfusion practices in neurocritical care are based on a rigid hemoglobin threshold, a view that excludes cerebral metabolic demands and specific needs. An RCT exploring these concepts is warranted. |
| first_indexed | 2024-12-11T04:33:58Z |
| format | Article |
| id | doaj.art-fd4e83885a1643c29c003271cb9e25d6 |
| institution | Directory Open Access Journal |
| issn | 2197-425X |
| language | English |
| last_indexed | 2024-12-11T04:33:58Z |
| publishDate | 2018-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Intensive Care Medicine Experimental |
| spelling | doaj.art-fd4e83885a1643c29c003271cb9e25d62022-12-22T01:20:47ZengSpringerOpenIntensive Care Medicine Experimental2197-425X2018-11-016111710.1186/s40635-018-0210-5The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injuryJudith Bellapart0Kylie Cuthbertson1Kimble Dunster2Sara Diab3David G. Platts4Christopher Raffel5Levon Gabrielian6Adrian Barnett7Jennifer Paratz8Rob Boots9John F. Fraser10Critical Care Research Group, University of QueenslandHistopathology Department, Royal Brisbane and Women’s HospitalCritical Care Research Group, University of QueenslandCritical Care Research Group, University of QueenslandCritical Care Research Group, University of QueenslandCritical Care Research Group, University of QueenslandMedical School Research CentreCritical Care Research Group, University of QueenslandSchool of Medicine, University of QueenslandIntensive Care Department, Royal Brisbane and Women’s HospitalCritical Care Research Group, University of QueenslandAbstract Background Cerebral regional microcirculation is altered following severe head injury. In addition to tissue disruption, partial pressure of tissue oxygenation is impaired due to an increase in the oxygen tissue gradient. The heterogenic distribution of cerebral microcirculation is multifactorial, and acute anemia challenges further the delivery of oxygen to tissues. Currently, a restrictive transfusion threshold is globally applied; however, it is unclear how anemia modifies regional cerebral microcirculation; hence, it is unclear if by aiming to a global endpoint, specific anatomical regions undergo ischemia. This study aims to quantify the temporal changes in cerebral microcirculation after severe head injury, under the effect of anemia and transfusion. It also aims to assess its effects specifically at the ischemic penumbra compared to contralateral regions and its interactions with axonal integrity in real time. Twelve ovine models were subjected to a severe contusion and acceleration-deceleration injury. Normovolemic anemia to a restrictive threshold was maintained after injury, followed by autologous transfusion. Direct quantification of cerebral microcirculation used cytometric count of color-coded microspheres. Axonal injury was assessed using amyloid precursor protein staining. Results A mixed-effect regression model from pre-transfusion to post-transfusion times with a random intercept for each sheep was used. Cerebral microcirculation amongst subjects with normal intracranial pressure was maintained from baseline and increased further after transfusion. Subjects with high intracranial pressure had a consistent reduction of their microcirculation to ischemic thresholds (20–30 ml/100 g/min) without an improvement after transfusion. Cerebral PtiO2 was reduced when exposed to anemia but increased in a 9.6-fold with transfusion 95% CI 5.6 to 13.6 (p value < 0.001). Conclusions After severe head injury, the exposure to normovolemic anemia to a restrictive transfusion threshold, leads to a consistent reduction on cerebral microcirculation below ischemic thresholds, independent of cerebral perfusion pressure. Amongst subjects with raised intracranial pressure, microcirculation does not improve after transfusion. Cerebral oxymetry is impaired during anemia with a statistically significant increase after transfusion. Current transfusion practices in neurocritical care are based on a rigid hemoglobin threshold, a view that excludes cerebral metabolic demands and specific needs. An RCT exploring these concepts is warranted.http://link.springer.com/article/10.1186/s40635-018-0210-5AnemiaAPP stainingHistologyMicrocirculationMicrospheres |
| spellingShingle | Judith Bellapart Kylie Cuthbertson Kimble Dunster Sara Diab David G. Platts Christopher Raffel Levon Gabrielian Adrian Barnett Jennifer Paratz Rob Boots John F. Fraser The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury Intensive Care Medicine Experimental Anemia APP staining Histology Microcirculation Microspheres |
| title | The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| title_full | The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| title_fullStr | The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| title_full_unstemmed | The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| title_short | The effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| title_sort | effects of normovolemic anemia and blood transfusion on cerebral microcirculation after severe head injury |
| topic | Anemia APP staining Histology Microcirculation Microspheres |
| url | http://link.springer.com/article/10.1186/s40635-018-0210-5 |
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