Stress echocardiography as a gatekeeper to donation in aged marginal donor hearts: anatomic and pathologic correlations of abnormal stress echocardiography results.

BACKGROUND: Owing to the shortage of donor hearts, the criteria for acceptance have been considerably expanded. Pharmacologic stress echocardiography is highly accurate in identifying prognostically significant coronary artery disease, but brain death and catecholamine storm in potential heart donors may substantially alter the cardiovascular response to stress. This study assessed correlates of an abnormal resting/stress echocardiography results in potential donors. METHODS: From April 2005 to December 2007, 18 marginal candidate donors (9 men) aged 58 +/- 5 years were initially enrolled. After legal declaration of brain death, all marginal donors underwent bedside echocardiography, with baseline and (when resting echocardiography was normal) dipyridamole (0.84 mg/kg in 6 min) or dobutamine (up to 40 microg/kg/min) stress echo. Non-eligible hearts (with abnormal rest or stress echo findings) were excluded and underwent cardioautoptic verification. RESULTS: Resting echocardiography showed wall motion abnormalities in 5 patients (excluded from donation). Stress echocardiography was performed in the remaining 13 (dipyridamole in 11; dobutamine in 2). Results were normal in 7, of which 6 were uneventfully transplanted in marginal recipients. Results were abnormal in 6, and autoptic verification performed showed coronary artery disease in 5, and initial cardiomyopathy in 1. CONCLUSIONS: Bedside pharmacologic stress echocardiography can safely be performed in candidate heart donors, is able to unmask occult coronary artery disease or cardiomyopathy, and shows potential to extend donor criteria in heart transplantation. Further experience with using marginal donors is needed before exact guidelines can be established.

Cerebral arterio-venous pCO2 difference, estimated respiratory quotient, and early posttraumatic outcome: comparison with arterio-venous lactate and oxygen differences.

Arterio-venous pCO2 difference (AVDpCO2) and estimated respiratory quotient, the ratio between AVDpCO2 and arterio-venous O2 difference, may be potentially useful estimators of irreversible posttraumatic global cerebral ischemia. Our aim was to evaluate their relevance, along with arterio-venous lactate difference (AVDL) and lactate oxygen index (LOI), in early outcome prediction. The retrospective study involved 55 patients with severe head injury, admitted consecutively in a multidisciplinary intensive care unit of a general hospital. A retrograde jugular catheter was placed as soon as possible, allowing for 324 simultaneous arterio-jugular samples to be taken throughout the first 48-hour postinjury. Early brain death (within 48 h) was assumed to be due to early global ischemia. A multivariate model including clinical and radiologic descriptors and jugular bulb variables showed that a widening of AVDL and LOI was associated with early brain death. Whereas in the patients who died, a progressive worsening of AVDpCO2 and estimated respiratory quotient, associated with corresponding changes in AVDL and LOI were observed, in patients who survived the widening of AVDpCO2 normalized along with that of arterio-venous O2 difference. These findings suggest that the isolated measurement of widening AVDpCO2 is not specific for global cerebral ischemia, but its observation over time could be potentially more useful.

Global cerebral blood flow and CPP after severe head injury: a xenon-CT study.

OBJECTIVE: To evaluate the association between global cerebral blood flow and different cerebral perfusion pressure ranges in severe head injury. DESIGN: A retrospective study SETTING: Neurosurgical and trauma patients in an intensive care unit in a regional hospital. PATIENTS AND PARTICIPANTS: Out of a series of 237 consecutive patients with severe head injuries (GCS

Cerebral blood flow in traumatic contusions is predominantly reduced after an induced acute elevation of cerebral perfusion pressure.

OBJECTIVE: To evaluate the response to an acute elevation of cerebral perfusion pressure (CPP) of the regional cerebral blood flow (rCBF) measured in the edematous area of traumatic contusions. METHODS: rCBF was measured in the intracontusional low-density area, in the pericontusional healthy-appearing brain tissue surrounding the contusion, in a healthy-appearing area in the contralateral hemisphere, in 16 head-injured patients with 16 traumatic contusions larger than 2 cm at baseline, and after 20 minutes of norepinephrine-induced 20-mmHg elevation of CPP levels. RESULTS: After an induced acute elevation of CPP from baseline values of 65.8 ml/100 g/min (standard deviation, 8.6) to final values of 88.7 ml/100 g/min (standard deviation, 8.9; P < or = 0.0001), we found that rCBF mean levels decreased in the intracontusional low-density area (P = 0.0278), and change in rCBF was inversely associated to the baseline values. After grouping contusions according to the rCBF response to induced acute CPP elevation, rCBF mean values recorded at baseline were significantly lower in lesions with "rCBF improvement" than in those with "rCBF reduction" in the intracontusional low-density area (P = 0.0435). CONCLUSION: Our findings suggest that CPP elevation induced by norepinephrine is effective in improving contusional rCBF only in selected cases, which are represented by a subset of contusions with critical perfusion, which can be identified by rCBF measurements. Conversely, in contusions with rCBF higher than critical low values, the CPP elevation could probably induce a temporary breakdown of the blood brain barrier, and the norepinephrine leads to a vasoconstriction with a worsening of regional perfusion.

Xenon-CT and transcranial Doppler in poor-grade or complicated aneurysmatic subarachnoid hemorrhage patients undergoing aggressive management of intracranial hypertension.

OBJECTIVE: To evaluate whether elevated flow velocimetry values are associated with critically reduced cerebral blood flow values in deeply sedated patients with acute aneurysmatic subarachnoid hemorrhage and in whom the detection of clinical vasospasm is not feasible. DESIGN: Retrospective analysis of prospectively collected data. SETTING: Neurosurgical and trauma patients in an intensive care unit in a regional hospital. PATIENTS AND PARTICIPANTS: Twenty-nine patients in the acute phase following subarachnoid hemorrhage who were sedated and ventilated for elevated intracranial pressure, transcranial Doppler vasospasm, or respiratory failure and were studied with at least a coupled xenon-CT/transcranial Doppler study. MEASUREMENTS AND RESULTS: Combined measurement and comparison of cerebral blood flow by means of xenon-CT and of mean velocity by means of transcranial Doppler in middle cerebral artery territories. The case mix studied was consistent with patients' predominantly poor grade and with a complicated course. The results suggest that in sedated patients flow velocity and measured cortical mixed cerebral blood flow are not correlated, and, more specifically, that flow velocities values above 120 or 160 cm/s and Lindegaard index above 3 are not associated with an ischemic regional cerebral blood flow. Conversely, as many as 55% of the xenon-CT studies were associated with hyperemia. CONCLUSIONS: In patients with elevated intracranial pressure, mean middle cerebral artery flow velocity or Lindegaard Index does not help to detect critical cerebral blood flow nor elevated cerebral blood flow.

Factors associated with neurological outcome and lesion progression in traumatic subarachnoid hemorrhage patients.

OBJECTIVE: Traumatic subarachnoid hemorrhage (tSAH) is a frequent finding after closed-head injuries, and its presence is a powerful factor associated with poor outcome. The exact mechanism linking tSAH and an adverse outcome is poorly understood. The aim of this study was to identify the factors that may predict outcomes and changes in the computed tomographic (CT) scans of lesions in a selected population of tSAH patients. METHODS: We evaluated 141 patients admitted consecutively from January 1, 1997, to January 31, 1999, with a CT diagnosis of tSAH. The admission and "worst" CT scans were recorded. CT scan changes were reported as "significant CT progression" (changes in the Marshall classification) or "any CT progression." The amount of subarachnoid blood was recorded using a modified Fisher classification. Outcome was assessed at 6 months after injury with the Glasgow Outcome Scale. RESULTS: Twenty-eight patients (19.9%) had an unfavorable Glasgow Outcome Scale outcome. In the univariate analysis, prognosis was significantly related to age, admission Glasgow Coma Scale score, Marshall CT classification score at admission and on the worst CT scan, amount of tSAH, and volume of the associated brain contusions. From multivariate analysis, the only factors independently related to outcome were the Glasgow Coma Scale score (P < 0.01) and size of the tSAH at admission (P < 0.001). Thirty-four patients (24.1%) had significant CT lesion progression, and 66 patients (46.8%) had some lesion progression. Patients having significant progression of the lesion had a higher risk of an unfavorable outcome (32 versus 10%; P = 0.004). Unadjusted factors predicting CT progression were the Glasgow Coma Scale score at admission, the Marshall classification at admission, the amount of subarachnoid blood, and the presence or volume of associated brain contusions at admission. Independent factors associated with significant CT progression were the amount of tSAH (P < 0.001) and the presence or volume of brain contusions at admission (P < 0.001). CONCLUSION: The outcome of patients with tSAH at admission is related in a logistic regression analysis to the admission Glasgow Coma Scale score and to the amount of subarachnoid blood. These patients also have a significant risk of CT progression. The amount of subarachnoid blood and the presence of associated parenchymal damage are powerful independent factors associated with CT progression, thus linking poor outcomes and CT changes.

Centrifugal distribution of regional cerebral blood flow and its time course in traumatic intracerebral hematomas.

Cerebral blood flow (CBF) alterations following post-traumatic contusions have been demonstrated in recent papers. We evaluated regional CBF (rCBF) by means of Xenon-enhanced computerized tomography (Xe-CT) in 29 traumatic intracerebral hematomas, from 22 patients with severe head injury (GCS < or = 8). Fifty traumatic hematoma/Xe-CT CBF measurements were obtained from 39 Xe-CT studies performed during the acute phase (corresponding to the first 20 days post-injury). The rCBF was measured in three different regions of interest: the hemorrhagic core, the perihematoma edematous low-density area, and a 1-cm rim of perihematoma normal-appearing brain tissue, surrounding the edematous low-density area. We found a centrifugal improvement of rCBF as well as a decrease in the rates of CBF levels below 18 mL/100 g/min from the core to the periphery (p < 0.0001), which persisted over time. Ischemic rCBF values were detected in the perihematoma low-density area only in 24% of the traumatic hematomas. The time course of rCBF levels showed a reduced flow in the first 24 h, with a recovery of flow from day 2 to day 4, followed by another reduced flow (p < or = 0.0001) both in the perihematoma edematous low-density area and in the non-lesioned tissue. Our findings suggest that the only area with persistent ischemic values was the hemorrhagic core. Low rCBF levels seen in the perihematoma low-density area may only be ascribed partially to ischemia and can possibly recover over time. These results could encourage a surgical approach based on an early evacuation of the hemorrhagic core associated to a preservation of the surrounding edematous tissue.