Accuracy of transcranial Doppler ultrasonography and single-photon emission computed tomography in the diagnosis of angiographically demonstrated cerebral vasospasm.

OBJECT: The goal of this study was to assess the accuracy of the routine clinical use of transcranial Doppler (TCD) ultrasonography and SPECT in predicting angiographically demonstrated vasospasm. METHODS: Following receipt of institutional review board approval, the authors reviewed the records of patients with subarachnoid hemorrhage who had been admitted between 2004 and 2005 and underwent TCD ultrasonography and SPECT evaluations within 24 hours of cerebral angiography. Patients were categorized based on the presence or absence of vasospasm and/or hypoperfusion in the anterior cerebral arteries (ACAs), middle cerebral arteries (MCAs), and basilar arteries (BAs) or posterior cerebral arteries (PCAs) according to each imaging modality. Logistic regression was used to estimate the odds ratio (OR) of an angiographically demonstrated vasospasm also detected on TCD ultrasonography and SPECT. RESULTS: One hundred fifty-two patients (101 women) with a mean age (+/- standard deviation) of 53 +/- 13 years were included in the study. In the ACA, the OR of a vasospasm on TCD ultrasonography was 27 (95% confidence interval [CI] 3-243) and on SPECT 0.97 (95% CI 0.36-2.6); in the MCA, 17 (95% CI 5.4-55) and 2.0 (95% CI 0.71-5.5), respectively; in the BA, 4.4 (95% CI 0.72-27) and 5.6 (95% CI 0.89-36), respectively. There was no substantial change in the relative odds of a vasospasm when the findings on TCD ultrasonography and SPECT were considered jointly. CONCLUSIONS: Transcranial Doppler ultrasonography appears to be highly predictive of an angiographically demonstrated vasospasm in the MCA and ACA; however, its diagnostic accuracy was lower with regard to vasospasm in the BA. Single-photon emission computed tomography was not predictive of a vasospasm in any of the vascular territories assessed.

Transcranial Doppler ultrasonography: a diagnostic tool of increasing utility.

PURPOSE OF REVIEW: Since its introduction in 1982, transcranial Doppler ultrasonography has become an important diagnostic and monitoring tool in patients with surgical disease. It has applications in the perioperative period, as well as in the intensive care unit. It is therefore appropriate for the anesthesiologist to maintain an understanding of its current utility. RECENT FINDINGS: Transcranial Doppler has an established role in diagnosing cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage and for guiding transfusion therapy in children with sickle cell disease. It has application in the preoperative evaluation of patients with cerebrovascular disease, as well as that of an intraoperative monitor in carotid endarterectomy and carotid stenting. It is useful for detecting right-to-left shunts in settings in which transesophageal echocardiography is not desirable. Its value in settings such as traumatic brain injury, hepatic failure, and migraine headache has yet to be fully clarified. SUMMARY: Although there are several settings in which transcranial Doppler has well established usefulness, there are many more in which it is likely valuable, such as traumatic brain injury, ischemic stroke, and fulminant hepatic failure. Further research is needed in these fields to elucidate the exact role for transcranial Doppler.

Effect of equiosmolar solutions of mannitol versus hypertonic saline on intraoperative brain relaxation and electrolyte balance.

BACKGROUND: The purpose of the study was to compare the effect of equiosmolar solutions of mannitol and hypertonic saline (HS) on brain relaxation and electrolyte balance. METHODS: After institutional review board approval and informed consent, patients with American Society of Anesthesiologists physical status II-IV, scheduled to undergo craniotomy for various brain pathologies, were enrolled into this prospective, randomized, double-blind study. Patients received 5 ml/kg 20% mannitol (n = 20) or 3% HS (n = 20). Partial pressure of carbon dioxide in arterial blood was maintained at 35-40 mmHg, and central venous pressure was maintained at 5 mmHg or greater. Hemodynamic variables, fluid balance, blood gases, electrolytes, lactate, and osmolality (blood, cerebrospinal fluid, urine) were measured at 0, 15, 30, and 60 min and 6 h after infusion; arteriovenous difference of oxygen, glucose, and lactate were calculated. The surgeon assessed brain relaxation on a four-point scale (1 = relaxed, 2 = satisfactory, 3 = firm, 4 = bulging). Appropriate statistical tests were used for comparison; P < 0.05 was considered significant. RESULTS: There was no difference in brain relaxation (mannitol = 2, HS = 2 points; P = 0.8) or cerebral arteriovenous oxygen and lactate difference between HS and mannitol groups. Urine output with mannitol was higher than with HS (P < 0.03) and was associated with higher blood lactate over time (P < 0.001, compared with HS). Cerebrospinal fluid osmolality increased at 6 h in both groups (P < 0.05, compared with baseline). HS caused an increase in sodium in cerebrospinal fluid over time (P < 0.001, compared with mannitol). CONCLUSION: Mannitol and HS cause an increase in cerebrospinal fluid osmolality, and are associated with similar brain relaxation scores and arteriovenous oxygen and lactate difference during craniotomy.

Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children.

There is little information on gender differences in cerebral autoregulation. The purpose of this study was to compare autoregulation of the anterior and posterior circulations using the tilt test method in healthy boys and girls who were 10-16 y of age. Transcranial Doppler was used to measure middle cerebral artery and basilar artery flow velocities (Vmca and Vbas). Cerebral autoregulation (ARI) of the middle cerebral (ARImca) and basilar arteries (ARIbas) was examined using the tilt test method. An ARI <0.4 indicates impaired autoregulation. Among the 13 boys and 13 girls, Vmca and Vbas were higher in girls. All children demonstrated intact autoregulation, but boys had higher ARImca than girls, whereas girls had higher ARIbas than boys. Girls demonstrated greater autoregulation in the basilar artery, whereas boys demonstrated greater autoregulation in the middle cerebral artery. Girls had higher flow velocities in both vessels. This study provides normative data on cerebral autoregulation of the posterior circulation in healthy, awake boys and girls.

Feeding intolerance as a result of small-intestine intussusception in a child with major burns.

Feeding intolerance is common in critically ill children. We present an unusual case of jejunojejunal intussusception causing feeding intolerance in a child with major burns. An 18-month-old female was admitted to the intensive care unit after sustaining a 65% TBSA burn. Following a decompressive laparotomy for abdominal compartment syndrome, nasojejunal feeds were started immediately after surgery, which she did not tolerate. A plain abdominal radiograph revealed a collection of intraluminal air and an abdominal CT revealed a proximal jejunojejunal intussusception. The patient underwent laparotomy and an uncomplicated reduction of the small-bowel intussusception (SBI). Successful enteral feedings were commenced on hospital day 24, and the patient was discharged to home after approximately a 4.5-month hospitalization. The major learning point is that SBI can cause feeding intolerance in the child with major burns. Despite the low incidence of SBI in critically ill children, arriving at a timely diagnosis is essential because the consequences of a missed or delayed diagnosis include intestinal ischemia, necrosis, or perforation. Because SBI defies diagnosis by techniques traditionally used to diagnose intussusception involving the colon, clinical suspicion for intussusception is needed to facilitate the urgent diagnosis and correction of feeding intolerance caused by mechanical obstruction.