Evaluation of the transient hyperemic response test in head-injured patients

1997 ◽  
Vol 86 (5) ◽  
pp. 773-778 ◽  
Author(s):  
Piotr Smielewski ◽  
Marek Czosnyka ◽  
Peter Kirkpatrick ◽  
John D. Pickard
Keyword(s):  
Flow Velocity ◽  
Clinical Condition ◽  
Cerebral Autoregulation ◽  
Injured Patient ◽  
Content Type ◽  
Response Test ◽  
Arterial Blood ◽  
Head Injured ◽  
Hyperemic Response ◽  
Fine Print

✓ The transient hyperemic response test has been shown to provide an index of cerebral autoregulation in healthy individuals and in patients who have suffered a subarachnoid hemorrhage. In this study, the test was applied to patients who had received a severe head injury, and the value of the test was assessed by comparing its result with the individual's clinical condition (Glasgow Coma Scale [GCS] score), cerebral perfusion pressure (CPP), transcranial Doppler wave form—derived index for cerebral autoregulation (relationship between the CPP and the middle cerebral artery flow velocity), and outcome (Glasgow Outcome Scale [GOS] score). Forty-seven patients, aged 16 to 63 years, with head injuries were included in the study. Signals of intracranial pressure, arterial blood pressure, flow velocity, and cortical microcirculatory flux were digitized and recorded for a period of 30 minutes using special computer software. Two carotid compressions were performed at the beginning of each recording. The transient hyperemic response ratio (THRR: the ratio of the hyperemic flow velocity recorded after carotid release and the precompression baseline flow velocity) was calculated, as was the correlation coefficient Sx used to describe the relationship between slow fluctuations in the systolic flow velocity and CPP throughout the period of recording. No significant changes in CPP were found during compression. There was a significant correlation between the THRR and the Sx (r = 0.49, p < 0.0001). The hyperemic response proved to be lower in patients who exhibited a poor clinical grade at presentation (GCS scores < 6, p = 0.01) and lower in patients achieving a poor outcome (GOS scores of 3, 4, and 5, p = 0.003). Loss of postcompression hyperemia occurred when the CPP fell below 50 mm Hg. The carotid compression test provides a simple index of cerebral autoregulation that is relevant to the clinical condition and outcome of the severely head injured patient.

Cerebral autoregulation following head injury

2001 ◽  
Vol 95 (5) ◽  
pp. 756-763 ◽  
Author(s):  
Marek Czosnyka ◽  
Piotr Smielewski ◽  
Stefan Piechnik ◽  
Luzius A. Steiner ◽  
John D. Pickard
Keyword(s):  
Head Injury ◽  
Cerebral Autoregulation ◽  
Perfusion Pressure ◽  
Content Type ◽  
Arterial Blood ◽  
Head Injured ◽  
The Mean ◽  
Injured Patients ◽  
The Relationship ◽  
Fine Print

Object. The goal of this study was to examine the relationship between cerebral autoregulation, intracranial pressure (ICP), arterial blood pressure (ABP), and cerebral perfusion pressure (CPP) after head injury by using transcranial Doppler (TCD) ultrasonography. Methods. Using ICP monitoring and TCD ultrasonography, the authors previously investigated whether the response of flow velocity (FV) in the middle cerebral artery to spontaneous variations in ABP or CPP provides reliable information about cerebral autoregulatory reserve. In the present study, this method was validated in 187 head-injured patients who were sedated and receiving mechanical ventilation. Waveforms of ICP, ABP, and FV were recorded over intervals lasting 20 to 120 minutes. Time-averaged mean FV and CPP were determined. The correlation coefficient index between FV and CPP (the mean index of autoregulation [Mx]) was calculated over 4-minute epochs and averaged for each investigation. The distribution of averaged mean FV values converged with the shape of the autoregulatory curve, indicating lower (CPP < 55 mm Hg) and upper (CPP > 105 mm Hg) thresholds of autoregulation. The relationship between the Mx and either the CPP or ABP was depicted as a U-shaped curve. Autoregulation was disturbed in the presence of intracranial hypertension (ICP ≥ 25 mm Hg) and when mean ABP was too low (ABP < 75 mm Hg) or too high (ABP > 125 mm Hg). Disturbed autoregulation (p < 0.005) and higher ICP (p < 0.005) occurred more often in patients with unfavorable outcomes than in those with favorable outcomes. Conclusions. Autoregulation not only is impaired when associated with a high ICP or low ABP, but it can also be disturbed by too high a CPP. The Mx can be used to guide intensive care therapy when CPP-oriented protocols are used.

Transcranial Doppler ultrasound studies of cerebral autoregulation and subarachnoid hemorrhage in the rabbit

1990 ◽  
Vol 73 (4) ◽  
pp. 601-610 ◽  
Author(s):  
Richard J. Nelson ◽  
Sheila Perry ◽  
Tony K. Hames ◽  
John D. Pickard
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Flow Velocity ◽  
Doppler Ultrasound ◽  
Transcranial Doppler ◽  
Cerebral Autoregulation ◽  
Time Course ◽  
Cerebrovascular Reactivity ◽  
Waveform Analysis ◽  
Content Type ◽  
Fine Print

✓ The authors describe a method for Doppler ultrasound recording of flow velocity in the basilar artery of normal rabbits and rabbits with experimental subarachnoid hemorrhage (SAH). With this transcranial Doppler (TCD) model, clinical assumptions regarding flow velocity/cerebral blood flow (CBF) relationships, autoregulatory responses, and Doppler spectral waveform analysis can be tested under controlled conditions and compared with established methods of CBF measurement (hydrogen clearance). The time course of changes in flow velocity following SAH (cerebral vasospasm) is successfully demonstrated using the experimental TCD method. There are significant differences in the flow velocity and CBF responses to hypercapnia, hypocapnia, and trimethaphan-induced hypotension which indicate that TCD cannot be considered a simple alternative to CBF measurement for the study of cerebrovascular reactivity and cerebral autoregulation.

Extravasation of angiographic contrast material from a torn middle meningeal artery into the diploi

1973 ◽  
Vol 38 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Moris I. Saba ◽  
Robert B. King
Keyword(s):  
Subdural Hematoma ◽  
Contrast Material ◽  
Injured Patient ◽  
Middle Meningeal Artery ◽  
Content Type ◽  
Head Injured Patient ◽  
Head Injured ◽  
Meningeal Artery ◽  
Fine Print

✓ Extravasation of contrast material during angiography in a head-injured patient was shown at operation to have occurred because of a fistula between a lacerated meningeal artery and the diploic spaces within the skull. Usually such extravasation is regarded as diagnostic evidence of an epidural or subdural hematoma, as had been suggested erroneously by the angiogram in this case.

Efficacy of moderate hypothermia in patients with severe head injury and intracranial hypertension refractory to mild hypothermia

2003 ◽  
Vol 99 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Tadahiko Shiozaki ◽  
Yoshikazu Nakajima ◽  
Mamoru Taneda ◽  
Osamu Tasaki ◽  
Yoshiaki Inoue ◽  
...  
Keyword(s):  
Intracranial Hypertension ◽  
Mild Hypothermia ◽  
Brain Temperature ◽  
Moderate Hypothermia ◽  
Content Type ◽  
Arterial Blood ◽  
Cell Counts ◽  
Head Injured ◽  
Injured Patients ◽  
Fine Print

Object. This study was performed to determine whether moderate hypothermia (31°C) improves clinical outcome in severely head injured patients whose intracranial hypertension cannot be controlled using mild hypothermia (34°C). Methods. Twenty-two consecutive severely head injured patients who fulfilled the following criteria were included in this study: an intracranial pressure (ICP) that remained higher than 40 mm Hg despite the use of mild hypothermia combined with conventional therapies; and a Glasgow Coma Scale score of 8 or less on admission. After the failure of mild hypothermia in combination with conventional therapies; patients were exposed to moderate hypothermia as quickly as possible. As brain temperature was reduced from 34 to 31°C, the volume of intravenous fluid infusion was increased significantly from 1.9 ± 0.9 to 2.6 ± 1.2 mg/kg/hr (p < 0.01), and the dose of dopamine infusion increased significantly from 4.3 ± 3.1 to 8.2 ± 4.4 µg/kg/min (p < 0.01). Nevertheless, mean arterial blood pressure and heart rate decreased significantly from 97.1 ± 13.1 to 85.1 ± 10.5 mm Hg (p < 0.01) and from 92.2 ± 13.8 to 72.2 ± 14.3 beats/minute at (p < 0.01) at 34 and 31°C, respectively. Arterial base excess was significantly aggravated from −3.3 ± 4 at 34°C to −5.6 ± 5.4 mEq/L (at 31°C; p < 0.05). Likewise, serum potassium concentration, white blood cell counts, and platelet counts at 31°C decreased significantly compared with those at 34°C (p < 0.01). In 19 (86%) of 22 patients, elevation of ICP could not be prevented using moderate hypothermia. In the remaining three patients, ICP was maintained below 40 mm Hg by inducing moderate hypothermia; however, these three patients died of multiple organ failure. These results clearly indicate that moderate hypothermia induces complications more severe than those induced by mild hypothermia without improving outcomes. Conclusions. The authors concluded that moderate hypothermia is not effective in improving clinical outcomes in severely head injured patients whose ICP remains higher than 40 mm Hg after treatment with mild hypothermia combined with conventional therapies.

Cerebral autoregulation following minor head injury

1997 ◽  
Vol 86 (3) ◽  
pp. 425-432 ◽  
Author(s):  
Elisabeth C. Jünger ◽  
David W. Newell ◽  
Gerald A. Grant ◽  
Anthony M. Avellino ◽  
Saadi Ghatan ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Head Injury ◽  
Cerebral Autoregulation ◽  
Minor Head Injury ◽  
Lower Blood Pressure ◽  
Content Type ◽  
Lower Blood ◽  
Head Injured ◽  
Injured Patients ◽  
Fine Print

✓ The purpose of this study was to determine whether patients with minor head injury experience impairments in cerebral autoregulation. Twenty-nine patients with minor head injuries defined by Glasgow Coma Scale (GCS) scores of 13 to 15 underwent testing of dynamic cerebral autoregulation within 48 hours of their injury using continuous transcranial Doppler velocity recordings and blood pressure recordings. Twenty-nine age-matched normal volunteers underwent autoregulation testing in the same manner to establish comparison values. The function of the autoregulatory response was assessed by the cerebral blood flow velocity response to induced rapid brief changes in arterial blood pressure and measured as the autoregulation index (ARI). Eight (28%) of the 29 patients with minor head injury demonstrated poorly functioning or absent cerebral autoregulation versus none of the controls, and this difference was highly significant (p = 0.008). A significant correlation between lower blood pressure and worse autoregulation was found by regression analysis in head-injured patients (r = 0.6, p < 0.001); however, lower blood pressure did not account for the autoregulatory impairment in all patients. Within this group of head-injured patients there was no correlation between ARI and initial GCS or 1-month Glasgow Outcome Scale scores. This study indicates that a significant number of patients with minor head injury may have impaired cerebral autoregulation and may be at increased risk for secondary ischemic neuronal damage.

Stress-induced malignant hyperthermia in a head-injured patient

1988 ◽  
Vol 68 (2) ◽  
pp. 297-299 ◽  
Author(s):  
Tony Feuerman ◽  
George F. Gade ◽  
Robert Reynolds
Keyword(s):  
Head Injury ◽  
Body Temperature ◽  
Malignant Hyperthermia ◽  
Injured Patient ◽  
Drug Induced ◽  
Content Type ◽  
Anesthetic Agents ◽  
Head Injured ◽  
Inhalational Anesthetic ◽  
Fine Print

✓ Susceptibility to malignant hyperthermia is a rare inherited myopathy. Hypermetabolic crises accompanied by a rise in body temperature to as high as 44°C are the hallmark of malignant hyperthermia episodes. These are triggered by inhalational anesthetic agents or depolarizing muscle-relaxant drugs. A similar condition exists in pigs; however, in addition to drug-induced attacks, episodes of malignant hyperthermia occur in these animals as a result of stress. It has been proposed that stress-induced malignant hyperthermia occurs in man. The present paper presents a case of stress-induced malignant hyperthermia in a 21-year-old man in whom the inciting stress was a head injury.

Intraoperative monitoring of substrate delivery during aneurysm and hematoma surgery: initial experience in 16 patients

1997 ◽  
Vol 87 (6) ◽  
pp. 809-816 ◽  
Author(s):  
Egon M. R. Doppenberg ◽  
Joe C. Watson ◽  
William C. Broaddus ◽  
Kathryn L. Holloway ◽  
Harold F. Young ◽  
...  
Keyword(s):  
Cerebral Oxygenation ◽  
Parent Artery ◽  
Content Type ◽  
Arterial Blood ◽  
Wide Range ◽  
Head Injured ◽  
Intracranial Hematomas ◽  
Temporary Occlusion ◽  
Injured Patients ◽  
Fine Print

✓ The effects of proximal occlusion of the parent artery during aneurysm surgery in humans are not fully understood, although this method is widely used. The reduction in substrate that can be tolerated by normal and subarachnoid hemorrhage (SAH)—affected brain is unknown. Therefore, the authors measured brain oxygen tension (brain PO2), carbon dioxide tension (brain PCO2), pH, and hemoglobin oxygen (HbO2) saturation before and after temporary occlusion in 12 patients with aneurysms. The effect of removal of a traumatic intracranial hematoma on cerebral oxygenation was also studied in four severely head injured patients. A multiparameter sensor was placed in the cortex of interest and locked by means of a specially designed skull bolt. The mean arterial blood pressure, inspired O2 fraction, and end-tidal PCO2 were analyzed. Brain PO2 and HbO2 saturation data were collected every 10 seconds. Descriptive and nonparametric analyses were used to analyze the data. A wide range in baseline PO2 was seen, although a decrease from baseline in brain PO2 was found in all patients. During temporary occlusion, brain PO2 in patients with unruptured aneurysm (seven patients) dropped significantly, from 60 ± 31 to 27 ± 17 mm Hg (p < 0.05). In the SAH group (five patients), the brain PO2 dropped from 106 ± 74 to 87 ± 73 mm Hg (not significant). Removal of intracranial hematomas in four severely head injured patients resulted in a significant increase in brain PO2, from 13 ± 9 to 34 ± 13 mm Hg (p < 0.05). The duration of safe temporary occlusion could not be determined from this group of patients, because none developed postoperative deterioration in their neurological status. However, the data indicate that this technique is useful to detect changes in substrate delivery during intraoperative maneuvers. This study also reemphasizes the need for emergency removal of intracranial hematomas to improve substrate delivery in severely head injured patients.

Hemodynamic characterization of intracranial pressure plateau waves in head-injured patients

1999 ◽  
Vol 91 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Marek Czosnyka ◽  
Piotr Smielewski ◽  
Stefan Piechnik ◽  
Eric A. Schmidt ◽  
Pippa G. Al-Rawi ◽  
...  
Keyword(s):  
Intracranial Pressure ◽  
Flow Velocity ◽  
Reduced Pressure ◽  
Content Type ◽  
Plateau Waves ◽  
Compensatory Reserve ◽  
Head Injured ◽  
Clinical Consequences ◽  
Injured Patients ◽  
Fine Print

Object. Plateau waves of intracranial pressure (ICP) are often recorded during intensive care monitoring of severely head injured patients. They are traditionally interpreted as meaningful secondary brain insults because of the dramatic decrease in cerebral perfusion pressure (CPP). The aim of this study was to investigate both the hemodynamic profile and the clinical consequences of plateau waves.Methods. One hundred sixty head-injured patients were studied using continuous monitoring of ICP; almost 20% of these patients exhibited plateau waves. In 96 patients arterial pressure, ICP, and transcranial Doppler (TCD) blood flow velocity were studied daily for 20 minutes to 3 hours. Sixteen episodes of plateau waves in eight patients were recorded and analyzed.The dramatic increase in ICP was followed by a profound fall in CPP (by 45%). In contrast, flow velocity fell by only 20%. Autoregulation was documented to be intact both before and after plateau but was disturbed during the wave (p < 0.05). Pressure-volume compensatory reserve was always depleted before the wave. Cerebrovascular resistance decreased during the wave by 60% (p <0.05) and TCD pulsatility increased (p <0.05). Plateau waves did not increase the probability of an unfavorable outcome following injury.Conclusions. The authors have confirmed that the plateau waves are a hemodynamic phenomenon associated with cerebrovascular vasodilation. They are observed in patients with preserved cerebral autoregulation but reduced pressure-volume compensatory reserve.

Cerebral hemorrhage and edema following brain biopsy in rats: significance of mean arterial blood pressure

2000 ◽  
Vol 92 (1) ◽  
pp. 100-107 ◽  
Author(s):  
Helene Benveniste ◽  
Katie R. Kim ◽  
Laurence W. Hedlund ◽  
John W. Kim ◽  
Allan H. Friedman
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Neurosurgical Procedures ◽  
Shr Rats ◽  
Mr Microscopy ◽  
Content Type ◽  
Wky Rats ◽  
Arterial Blood ◽  
Fine Print

Object. It is taken for granted that patients with hypertension are at greater risk for intracerebral hemorrhage during neurosurgical procedures than patients with normal blood pressure. The anesthesiologist, therefore, maintains mean arterial blood pressure (MABP) near the lower end of the autoregulation curve, which in patients with preexisting hypertension can be as high as 110 to 130 mm Hg. Whether patients with long-standing hypertension experience more hemorrhage than normotensive patients after brain surgery if their blood pressure is maintained at the presurgical hypertensive level is currently unknown. The authors tested this hypothesis experimentally in a rodent model.Methods. Hemorrhage and edema in the brain after needle biopsy was measured in vivo by using three-dimensional magnetic resonance (MR) microscopy in the following groups: WKY rats, acutely hypertensive WKY rats, spontaneously hypertensive rats (SHR strain), and SHR rats treated with either sodium nitroprusside or nicardipine. Group differences were compared using Tukey's studentized range test followed by individual pairwise comparisons of groups and adjusted for multiple comparisons.There were no differences in PaCO2, pH, and body temperature among the groups. The findings in this study indicated that only acutely hypertensive WKY rats had larger volumes of hemorrhage. Chronically hypertensive SHR rats with MABPs of 130 mm Hg did not have larger hemorrhages than normotensive rats. There were no differences in edema volumes among groups.Conclusions. The brains of SHR rats with elevated systemic MABPs are probably protected against excessive hemorrhage during surgery because of greater resistance in the larger cerebral arteries and, thus, reduced cerebral intravascular pressures.

Contribution of CSF and vascular factors to elevation of ICP in severely head-injured patients

1987 ◽  
Vol 66 (6) ◽  
pp. 883-890 ◽  
Author(s):  
Anthony Marmarou ◽  
Angelo L. Maset ◽  
John D. Ward ◽  
Sung Choi ◽  
Danny Brooks ◽  
...  
Keyword(s):  
Severe Head Injury ◽  
Ventricular Catheter ◽  
Outflow Resistance ◽  
Content Type ◽  
Relative Contribution ◽  
Temporal Course ◽  
Head Injured ◽  
Predominant Factor ◽  
Injured Patients ◽  
Fine Print

✓ The authors studied the relative contribution of cerebrospinal fluid (CSF) and vascular parameters to the level of intracranial pressure (ICP) in 34 severely head-injured patients with a Glasgow Coma Scale score of less than 8. This was accomplished by first characterizing the temporal course of CSF formation and outflow resistance during the 5-day period postinjury. The CSF formation and outflow resistance were obtained from pressure responses to bolus addition and removal of fluid from an indwelling ventricular catheter. The vascular contribution to the level of ICP was assessed by withdrawing fluid at its rate of formation and observing the resultant change in equilibrium ICP level. It was found that, with the exception of patients with subarachnoid hemorrhage, CSF parameters accounted for approximately one-third of the ICP rise after severe head injury, and that a vascular mechanism may be the predominant factor in elevation of ICP.

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