Abstract
IntroductionTemperature changes are common in patients in a neurosurgical intensive care unit (NICU): fever is frequent among severe cases and hypothermia is used after cardiac arrest and is currently being tested in clinical trials to lower intracranial pressure (ICP). This study investigated cerebral hemodynamics when body temperature varies in acute brain injured patients.MethodsWe enrolled 26 patients, 14 with acute brain injury who developed fever and were given antipyretic therapy (defervescence group) and 12 who underwent an intracranial neurosurgical procedure and developed hypothermia in the operating room; once admitted to the NICU, still under anesthesia, they were re-warmed before waking (re-warming group). We measured cerebral blood flow velocity (CBF-V) and pulsatility index (PI) at the middle cerebral artery using transcranial color-coded duplex sonography (TCCDS).ResultsIn the defervescence group mean CBF-V decreased from 75 ± 26 (95% CI 65 to 85) to 70 ± 22 cm/s (95% CI 61 to 79) (P = 0.04); the PI also fell, from 1.36 ± 0.33 (95% CI 1.23 to 1.50) to 1.16 ± 0.26 (95% CI 1.05 to 1.26) (P = 0.0005). In the subset of patients with ICP monitoring, ICP dropped from 16 ± 8 to 12 ± 6 mmHg (P = 0.003). In the re-warming group mean CBF-V increased from 36 ± 10 (95% CI 31 to 41) to 39 ± 13 (95% CI 33 to 45) cm/s (P = 0.04); the PI rose from 0.98 ± 0.14 (95% CI 0.91 to 1.04) to 1.09 ± 0.22 (95% CI 0.98 to 1.19) (P = 0.02).ConclusionsBody temperature affects cerebral hemodynamics as evaluated by TCCDS; when temperature rises, CBF-V increases in parallel, and viceversa when temperature decreases. When cerebral compliance is reduced and compensation mechanisms are exhausted, even modest temperature changes can greatly affect ICP.
Highlights
Temperature changes are common in patients in a neurosurgical intensive care unit (NICU): fever is frequent among severe cases and hypothermia is used after cardiac arrest and is currently being tested in clinical trials to lower intracranial pressure (ICP)
Cerebral monitoring showed a reduction in ICP from 16 ± 8 to 12 ± 6 mmHg (P = 0.003) (Figure 1A) cerebral perfusion pressure (CPP) did not change (Figure 1B)
cerebral blood flow (CBF)-V decreased: mean velocity from 75 ± 26 to 70 ± 22 cm/s (P = 0.04) and systolic peak velocity from 144 ± 54 to 126 ± 41 cm/s (P = 0.002)
Summary
Temperature changes are common in patients in a neurosurgical intensive care unit (NICU): fever is frequent among severe cases and hypothermia is used after cardiac arrest and is currently being tested in clinical trials to lower intracranial pressure (ICP). This study investigated cerebral hemodynamics when body temperature varies in acute brain injured patients. A different technique, transcranial color-coded duplex sonography (TCCDS), measures CBF velocity (CBF-V) in a particular tract of a specific vessel. From this measurement, CBF is estimated according to a mathematical equation [8]. In this study we investigated cerebral hemodynamics using TCCDS, at different body temperatures in patients with acute brain injury. We explored two conditions: (1) defervescence, when febrile patients were treated with antipyretic drugs and (2) re-warming, after intracranial neurosurgical procedures
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