Tag Archives: X-Ray Computed Tomography

Suspected Cerebral Edema in Diabetic Ketoacidosis: Is There Still a Role for Head CT in Treatment Decisions? (Colman)

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Soto-Rivera CL, Asaro LA, Agus MS, DeCourcey DD. Suspected Cerebral Edema in Diabetic Ketoacidosis: Is There Still a Role for Head CT in Treatment Decisions?  Pediatr Crit Care Med. 2017 Jan 19. [Epub ahead of print]

OBJECTIVES: Neurologic deterioration associated with cerebral edema in diabetic ketoacidosis is typically sudden in onset, progresses rapidly, and requires emergent treatment. The utility of brain imaging by head CT in decisions to treat for cerebral edema has not been previously studied. The objective of this study was to describe the characteristics of pediatric patients with diabetic ketoacidosis who develop altered mental status and evaluate the role of head CT in this cohort.

DESIGN: Retrospective analysis of clinical, biochemical, and radiologic data.

SETTING: Tertiary care children’s hospital (2004-2010).

PATIENTS: Six hundred eighty-six admissions of patients (< 26 yr) with diabetic ketoacidosis.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Altered mental status was documented during 96 of 686 diabetic ketoacidosis admissions (14%). Compared with alert patients, those with altered mental status were younger (median, 12.0 vs 13.1 yr; p = 0.007) and more acidotic (pH, 7.04 vs 7.19; p < 0.001), with higher serum osmolality (328 vs 315 mOsm/kg; p < 0.001) and longer hospital length of stay (4.5 vs 3 d; p = 0.002). Head CT was performed during 60 of 96 diabetic ketoacidosis admissions with altered mental status (63%), 16 (27%) of which had abnormal results. Hyperosmolar therapy for cerebral edema was given during 23 of the 60 admissions (38%), during which 12 (52%) had normal head CT results, eight of these 12 (67%) after cerebral edema treatment and four (33%) before. Of the 11 admissions with abnormal head CT results that received hyperosmolar therapy, four head CT scan (36%) occurred after hyperosmolar treatment and seven (64%) before. For the 11 admissions with head CT before cerebral edema treatment, there was a median 2-hour delay between head CT and hyperosmolar therapy.

CONCLUSIONS: In this single-center retrospective study, there was no evidence that decisions about treatment of patients with diabetic ketoacidosis and suspected cerebral edema were enhanced by head CT, and head CT may have led to a significant delay in hyperosmolar therapy.

Altered Mental Status in ICU Patients: Diagnostic Yield of Noncontrast Head CT for Abnormal and Communicable Findings. (Stulce)

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Chokshi FH, et al. Altered Mental Status in ICU Patients: Diagnostic Yield of Noncontrast Head CT for Abnormal and Communicable Findings. Crit Care Med. 2016 Dec;44(12):e1180-e1185.

OBJECTIVE: To evaluate the diagnostic yield of noncontrast head CT for acute communicable findings in ICU patients specifically scanned for altered mental status.

DESIGN: Retrospective observational cohort study.

SETTING: University Hospital Neuroscience, Medical, and Surgical ICUs.

PATIENTS: ICU patients with new-onset altered mental status.

INTERVENTION: Noncontrast head CT.

MEASUREMENTS AND MAIN RESULTS: Reports on head CTs from two university hospitals performed for the sole indication of altered mental status in ICU patients between July 2011 and June 2013 were reviewed for 1) acute (new or worsening) hemorrhage, 2) mass effect/herniation, 3) infarction, and 4) hydrocephalus. Subgroup analyses of positive findings were performed by 1) ICU group type, 2) age, and 3) race. A total of 2,486 head CTs were performed in 1,357 patients whose age ranged from 14 to 116 years (median, 59; mean, 57.6 ± 16). Acute communicable findings in at least one of four categories were present in 22.8% (566/2,486) of examinations, with hydrocephalus being most common (11.5% [286/2,486]). The frequency of any acute communicable findings in neuroscience, medical, and surgical ICUs was 28.6% (471/1,648), 9.8% (43/440), and 13.1% (52/398), respectively. Neuroscience ICU head CTs had significantly higher rates of acute communicable findings in all categories, except for acute infarction, compared with the other two ICUs (p < 0.001). Acute hydrocephalus (13.6% vs 7.4%; p < 0.001) and mass effect (6.7% vs 4.3%; p = 0.01) were more common in patients less than 65 years. For other acute categories, no significant difference was noted by age. There was no significant difference in the likelihood of a positive examination by race.

CONCLUSIONS: Almost one in four head CTs in a university ICU patient population performed for primary indication of altered mental status yields abnormal communicable findings. In this patient population, utilization management barriers to examination ordering should be minimized.

Body position changes redistribute lung computed-tomographic density in patients with acute respiratory failure: impact and clinical fallout through the following 20 years. (Stockwell)

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Gattinoni L, Pesenti A, Carlesso E. Body position changes redistribute lung computed-tomographic density in patients with acute respiratory failure: impact and clinical fallout through the following 20 years. Intensive Care Med. 2013 Nov;39(11):1909-1915.

ABSTRACT: In patients with acute respiratory distress syndrome (ARDS), in supine position, there is a decrease of inflation along the sternum vertebral axis, up to lung collapse. In 1991 we published a report showing that, in ARDS patients, shifting from supine to prone position led immediately to the inversion of the inflation gradient and to a redistribution of densities from dorsal to ventral lung regions. This led to a “sponge model” as a wet sponge, similar to a heavy edematous lung, squeezes out the gas in the most dependent regions, due to the weight-related increase of the compressive forces. The sponge model accounts for density distribution in prone position, for which the unloaded dorsal regions are recruited, while the loaded ventral region, collapses. In addition, the sponge model accounts for the mechanism through which the positive end-expiratory pressure acts as counterforce to oppose the collapsing, compressing forces. The final result of proning was that the inversion of gravitational forces, together with other factors such as lung-chest wall shape-matching and the heart weight led to a more homogeneous distribution of inflation throughout the lung parenchyma. This is associated with oxygenation improvement as the dorsal recruitment, for anatomical reasons, prevails on the ventral de-recruitment. The more homogeneous distribution of inflation (i.e. of stress and strain) decreases/prevents the ventilator-induced lung injury, as consistently shown in animal experiments. Finally, and a series of clinical trials led to the conclusion that in patients with severe ARDS, the prone position provides a significant survival advantage.

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The use of computed tomography in pediatrics and the associated radiation exposure and estimated cancer risk. (Hebbar)

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JAMA Pediatr. 2013 Aug 1;167(8):700-7. PMID: 23754213

IMPORTANCE: Increased use of computed tomography (CT) in pediatrics raises concerns about cancer risk from exposure to ionizing radiation.

OBJECTIVES: To quantify trends in the use of CT in pediatrics and the associated radiation exposure and cancer risk. DESIGN Retrospective observational study.

SETTING: Seven US health care systems. PARTICIPANTS The use of CT was evaluated for children younger than 15 years of age from 1996 to 2010, including 4 857 736 child-years of observation. Radiation doses were calculated for 744 CT scans performed between 2001 and 2011.

MAIN OUTCOMES AND MEASURES: Rates of CT use, organ and effective doses, and projected lifetime attributable risks of cancer.

RESULTS: The use of CT doubled for children younger than 5 years of age and tripled for children 5 to 14 years of age between 1996 and 2005, remained stable between 2006 and 2007, and then began to decline. Effective doses varied from 0.03 to 69.2 mSv per scan. An effective dose of 20 mSv or higher was delivered by 14% to 25% of abdomen/pelvis scans, 6% to 14% of spine scans, and 3% to 8% of chest scans. Projected lifetime attributable risks of solid cancer were higher for younger patients and girls than for older patients and boys, and they were also higher for patients who underwent CT scans of the abdomen/pelvis or spine than for patients who underwent other types of CT scans. For girls, a radiation-induced solid cancer is projected to result from every 300 to 390 abdomen/pelvis scans, 330 to 480 chest scans, and 270 to 800 spine scans, depending on age. The risk of leukemia was highest from head scans for children younger than 5 years of age at a rate of 1.9 cases per 10 000 CT scans. Nationally, 4 million pediatric CT scans of the head, abdomen/pelvis, chest, or spine performed each year are projected to cause 4870 future cancers. Reducing the highest 25% of doses to the median might prevent 43% of these cancers.

CONCLUSIONS AND RELEVANCE: The increased use of CT in pediatrics, combined with the wide variability in radiation doses, has resulted in many children receiving a high-dose examination. Dose-reduction strategies targeted to the highest quartile of doses could dramatically reduce the number of radiation-induced cancers.

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