Extremely low birth weight infants remain at increased risk of intraventricular hemorrhage from the fragile vascular bed of the germinal matrix; the roles of hypotension (ischemia) and reperfusion (hyperemia) in the development of intraventricular hemorrhage are still debated. Cerebrovascular pressure autoregulation protects the brain by maintaining constant cerebral blood flow despite changes in blood pressure. The ontogeny of cerebrovascular pressure autoregulation has not been well established and uncertainty remains about the optimal arterial blood pressure required to support brain perfusion. Another important aspect of premature cerebral hemodynamics is the critical closing pressure––the arterial blood pressure at which cerebral blood flow ceases. Interestingly, in premature infants, the critical closing pressure approximates the mean arterial blood pressure. Often in this unique population, cerebral blood flow occurs only during systole when the diastolic arterial blood pressure is equal to the critical closing pressure. Moreover, the diastolic closing margin, a metric of cerebral perfusion that normalizes diastolic arterial blood pressure to the critical closing pressure, may be a better measure than arterial blood pressure for defining cerebral perfusion in premature infants. Elevated diastolic closing margin has been associated with intraventricular hemorrhage. This review summarizes the current state of understanding of cerebral hemodynamics in premature infants.
Arterial Pressure ; Blood Pressure ; Brain ; Cerebrovascular Circulation ; Hemodynamics ; Hemorrhage ; Homeostasis ; Humans ; Hypotension ; Infant ; Infant, Low Birth Weight ; Infant, Newborn ; Infant, Premature ; Perfusion ; Reperfusion ; Systole ; Uncertainty

We hypothesized that when used in combination with cardiac troponins, heart-type fatty acid binding protein (H-FABP) would have greater diagnostic value than conventional markers for the early diagnosis of myocardial infarction (MI). Patients with typical chest pain at a single emergency department were consecutively enrolled. Initial blood samples were drawn for H-FABP, myoglobin, creatine kinase isoenzyme MB (CK-MB), and cardiac troponin-I (cTnI) measurements. MI was defined by serial cTnI measurements. To evaluate the adjunctive role of biochemical markers, we derived and compared logistic regression models predicting MI in terms of their discrimination (area under the receiver operating characteristics curve, AUC) and overall fit (Bayesian information criterion, BIC). Seventy-six of 170 patients were diagnosed as having MI. The AUC of cTnI, H-FABP, myoglobin, and CK-MB were 0.863, 0.827, 0.784, and 0.772, respectively. A logistic regression model using cTnI (P = 0.001) and H-FABP (P < 0.001) had the biggest AUC (0.900) and the best fit determined by BIC. Sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of this model at 30% probability were 81.6%, 80.9%, 4.26, and 0.23, respectively. H-FABP has a better diagnostic value than both myoglobin and CK-MB as an adjunct to cTnI for the early diagnosis of MI.
Aged ; Area Under Curve ; Biological Markers/blood ; Chest Pain/complications ; Creatine Kinase, MB Form/blood ; Early Diagnosis ; Fatty Acid-Binding Proteins/*blood ; Female ; Humans ; Logistic Models ; Male ; Middle Aged ; Myocardial Infarction/complications/*diagnosis ; Myoglobin/blood ; Point-of-Care Systems ; Predictive Value of Tests ; Troponin I/*blood

We hypothesized that when used in combination with cardiac troponins, heart-type fatty acid binding protein (H-FABP) would have greater diagnostic value than conventional markers for the early diagnosis of myocardial infarction (MI). Patients with typical chest pain at a single emergency department were consecutively enrolled. Initial blood samples were drawn for H-FABP, myoglobin, creatine kinase isoenzyme MB (CK-MB), and cardiac troponin-I (cTnI) measurements. MI was defined by serial cTnI measurements. To evaluate the adjunctive role of biochemical markers, we derived and compared logistic regression models predicting MI in terms of their discrimination (area under the receiver operating characteristics curve, AUC) and overall fit (Bayesian information criterion, BIC). Seventy-six of 170 patients were diagnosed as having MI. The AUC of cTnI, H-FABP, myoglobin, and CK-MB were 0.863, 0.827, 0.784, and 0.772, respectively. A logistic regression model using cTnI (P = 0.001) and H-FABP (P < 0.001) had the biggest AUC (0.900) and the best fit determined by BIC. Sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of this model at 30% probability were 81.6%, 80.9%, 4.26, and 0.23, respectively. H-FABP has a better diagnostic value than both myoglobin and CK-MB as an adjunct to cTnI for the early diagnosis of MI.
Aged ; Area Under Curve ; Biological Markers/blood ; Chest Pain/complications ; Creatine Kinase, MB Form/blood ; Early Diagnosis ; Fatty Acid-Binding Proteins/*blood ; Female ; Humans ; Logistic Models ; Male ; Middle Aged ; Myocardial Infarction/complications/*diagnosis ; Myoglobin/blood ; Point-of-Care Systems ; Predictive Value of Tests ; Troponin I/*blood

We developed an institutional protocol mandating emergency physicians to contact the interventional cardiologist directly in all cases of ST-segment elevation myocardial infarction (STEMI) and hypothesized that this would reduce door-to-balloontimes (DTBT). From January 2004 to July 2006, 208 patients with STEMI were treated with primary percutaneous coronary intervention (PCI). A total of 144 patients were treated before implementing the new protocol ("before") and 64 patients were treated after the implementation ("after"). The DTBT was significantly reduced from 148+/-101 min to 108+/-56 min (p<0.05). While only 25% of the "before'' patients received PCI within 90 min after arrival, 50% of the "after'' patients received PCI within 90 min (p<0.05). There were no significant differences between two groups in other outcomes (postprocedural TIMI flow, mortality, subsequent stroke, heart failure, shock, reinfarction, length of stay in intensive care unit, and the total hospital length of stay). In conclusion, mandating emergency physicians to directly notify interventional cardiologists of all STEMI patients reduces DTBT.
Aged ; *Angioplasty, Transluminal, Percutaneous Coronary ; Communication ; Electrocardiography ; Emergency Service, Hospital/*organization & administration ; Female ; Humans ; Male ; Middle Aged ; Myocardial Infarction/*therapy ; Patient Care Team/*organization & administration ; Physicians ; Time Factors