Core curriculum and competencies for advanced training in neurological intensive care: United Council for Neurologic Subspecialties guidelines.
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Clinical Competence↗
Biomedical subjects
Arthur Lam
Publications and source records attributed to Arthur Lam.
Program requirements for fellowship training in neurological intensive care: United Council for Neurologic Subspecialties guidelines.
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Critical Care↗
Dynamic perfusion computerized tomography in cerebral vasospasm following aneurysmal subarachnoid hemorrhage: a comparison with technetium-99m-labeled ethyl cysteinate dimer-single-photon emission computerized tomography.
OBJECT: The aim of this study was to correlate cerebral blood flow (CBF) and mean transient time (MTT) measured on dynamic perfusion computerized tomography (CT) with CBF using (99m)Tc ethyl cysteinate dimer-single-photon emission computerized tomography (SPECT) in patients with cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH). METHODS: Thirty-five patients with vasospasm following aneurysmal SAH (12 men and 23 women with a mean age of 49.3 +/- 10.1 years) underwent imaging studies; thus, 35 perfusion CT scans and 35 SPECT images were available for comparison. The CBF and MTT values in 12 different brain regions were defined relative to the interhemispheric occipital cortex values using perfusion CT scans and were compared with qualitative relative (rel)CBF estimated on SPECT images. In brain regions with normal, mild (relCBF 71-85%), moderate (relCBF 50-70%), and severe (relCBF < 50%) hypoperfusion on SPECT, the mean relCBF values measured on perfusion CT were 1.01 +/- 0.08, 0.82 +/- 0.22, 0.6 +/- 0.15, and 0.32 +/- 0.08, respectively (p < 0.0001); the mean relMTT values were 1.04 +/- 0.14, 1.4 +/- 0.31, 2.16 +/- 0.46, and 3.3 +/- 0.54, respectively (p < 0.0001). All but one brain region (30 regions) with severe hypoperfusion on SPECT images demonstrated relCBF values less than 0.6 and relMTT values greater than 2.5 on perfusion CT scans. CONCLUSIONS: Relative CBF and MTT values on perfusion CT showed a high concordance rate with estimated relCBF on SPECT in patients with vasospasm following aneurysmal SAH. Given its logistical advantages, perfusion CT may be a valuable method of assessing perfusion abnormality in the acute setting of vasospasm and in patients with an unstable condition following aneurysmal SAH.
Adult↗
Comparison of endovascular and surface cooling during unruptured cerebral aneurysm repair.
OBJECTIVE: To compare endovascular versus surface methods for the induction and reversal of hypothermia during neurosurgery in a multicenter, prospective, randomized study. METHODS: Patients undergoing elective open craniotomy for repair of an unruptured cerebral aneurysm (n = 153) were randomly assigned (2:1) to undergo whole-body hypothermia to 33 degrees C, either with an endovascular cooling device placed in the inferior vena cava via the femoral vein (n = 92) or with a surface convective air blanket (n = 61). Active rewarming was accomplished using the same devices. RESULTS: Cooling rates in endovascular and surface blanket groups averaged 4.77 and 0.87 degrees C/h, respectively (P < 0.001). When the first temporary arterial or aneurysm clip was placed, 99% of endovascular patients and 20% of surface blanket patients had reached the target of 33 degrees C (P < 0.001). Obese patients were cooled efficiently with the endovascular approach (3.56 degrees C/h). Rewarming rates averaged 1.88 degrees C/h for endovascular patients and 0.69 degrees C/h for surface blanket patients (P < 0.001). By the end of surgery, 89 and 53% of these patients, respectively, had rewarmed to at least 35 degrees C (P < 0.001). On leaving the operating room, 14% of endovascular patients and 28% of surface blanket patients were still intubated (P = 0.035). The overall safety of the two procedures was comparable. No clinically significant catheter-related thrombotic, bleeding, or infectious complications were reported in the endovascular group. CONCLUSION: Endovascular cooling provided superior induction, maintenance, and reversal of hypothermia compared with the surface blanket, without an increase in complications. Endovascular cooling may have clinical benefit for patients undergoing cerebrovascular surgery, as well as patients with acute stroke, head injury, or acute myocardial infarction.
Adolescent↗
Chronic cocaine exposure alters carbon dioxide reactivity but does not affect cerebral blood flow autoregulation in anesthetized dogs.
BACKGROUND: Cocaine use is common in trauma victims. Consequently, understanding how cocaine alters normal physiology is important to providing appropriate medical care for these patients. This study was designed to identify how chronic cocaine exposure alters cerebrovascular physiology. METHODS: Ten dogs (seven experimental, three control) were studied. Transcranial Doppler was used to measure CO2 reactivity and autoregulation of cerebral blood flow velocity (CBFvel). Measurements were made in anesthetized animals (0.6% or 1.8% isoflurane in oxygen and intravenous fentanyl) at baseline before cocaine exposure and then at weekly intervals for 4 weeks. During the 4-week study period, cocaine was administered intravenously four times per day. RESULTS: Cocaine did not alter autoregulation of CBFvel in response to changes in mean arterial pressure. However, cocaine markedly impaired CO2 reactivity in three of the seven animals. In this subset of animals, increasing Paco2 decreased CBFvel, which is consistent with vasoconstriction rather than vasodilation. CONCLUSION: Chronic cocaine exposure does not alter autoregulation of CBFvel but does alter CO2 reactivity in a subset of susceptible animals. If confirmed in humans, these findings have implications for traumatic brain injury patients who are chronic cocaine users. Specifically, the findings suggest that hyperventilation could exacerbate intracranial hypertension in a subset of these patients.
Anesthesia, General↗