Age-independent myocardial infarct quantification by signal intensity percent infarct mapping in swine.

PURPOSE: To test whether signal intensity percent infarct mapping (SI-PIM) accurately determines the size of myocardial infarct (MI) regardless of infarct age. MATERIALS AND METHODS: Forty-five swine with reperfused MI underwent 1.5T late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) after bolus injection of 0.2 mmol/kg Gd(DTPA) on days 2-62 following MI. Animals were classified into acute, healing, and healed groups by pathology. Infarct volume (IV) and infarct fraction (IF) were determined by two readers, using binary techniques (including 2-5 standard deviations [SD] above the remote, and full-width at half-maximum) and the SI-PIM method. Triphenyl-tetrazolium-chloride staining (TTC) was performed as reference. Bias (percent under/overestimation of IV relative to TTC) of each quantification method was calculated. Bland-Altman analysis was done to test the accuracy of the quantification methods, while intraclass correlation coefficient (ICC) analysis was done to assess intra- and interobserver agreement. RESULTS: Bias of the MRI quantification methods do not depend on the age of the MI. Full-width at half-maximum (FWHM) and SI-PIM gave the best estimate of MI volume determined by the reference TTC (P-values for the FWHM and SI-PIM methods were 0.183, 0.26, 0.95, and 0.073, 0.091, 0.73 in Group 1, Group 2, and Group 3, respectively), while using any of the binary thresholds of 2-4 SDs above the remote myocardium showed significant overestimation. The 5 SD method, however, provided similar IV compared to TTC and was shown to be independent of the size and age of MI. ICC analysis showed excellent inter- and intraobserver agreement between the readers. CONCLUSION: Our results indicate that the SI-PIM method can accurately determine MI volume regardless of the pathological stage of MI. Once tested, it may prove to be useful for the clinic.

A Simple Numerical Body Surface Mapping Parameter Signifies Successful Percutaneous Coronary Artery Intervention.

BACKGROUND: In coronary artery disease (CAD), body surface potential mapping (BSPM) may reveal minor electrical potential changes appearing in the depolarization phase even if pathological changes are absent on the conventional 12-lead ECG. We hypothesized that a simple BSPM parameter, Max/Min signifies successful percutaneous coronary intervention (PCI). METHODS: Ninety-two adult Caucasian patients with stable CAD and positive exercise test underwent coronary angiography. Seventy patients (age, 59 ± 8; 46 males) were revascularized by PCI (left anterior descending [LAD] in 38, right [RCA] in 17 and left circumflex [LCX] coronary artery in 15). Control groups contained 22 patients (age, 60 ± 8; 14 males) without intervention and 35 healthy subjects (age, 58 ± 2; 15 males). Left ventricular ejection fraction (LVEF, transthoracic echocardiography) and Max/Min BSPM parameter (63-lead Montreal system) were evaluated before and 4-40 days following coronary angiography. Max/Min was defined by the ratio of the highest maximum to the deepest minimum potential of all leads recorded by BSPM. RESULTS: Before PCI, Max/Min value of patients with LAD lesion (0.83 [0.74; 0.93]) was significantly lower while that with RCA lesion (1.63 [1.35; 1.99]) was significantly higher than that of healthy group (1.01 [0.970; 1.13]) (P < 0.05) and LVEF was significantly lower in LAD lesion (46.50% [43.00; 51.00]) than in the healthy group (55.00% [50.00; 58.75]) (P < 0.01). Max/Min value significantly increased from 0.83 [0.74; 0.93] to 0.92 [0.82; 0.99] (P < 0.01) following LAD PCI while significantly decreased from 1.63 [1.35; 1.98] to 1.35 [1.21; 1.43] (P < 0.01) post-RCA PCI. It did not vary significantly, however, either following LCX PCI or without intervention. LVEF significantly increased (from 46.50% [43.00; 51.00] to 49.00% [46.00; 51.00]) only after LAD PCI. CONCLUSION: Max/Min parameter is suitable to follow patients after LAD and RCA PCI.

[Dobutamine stress cardiovascular magnetic resonance imaging in patients with peripheral artery disease]. / Dobutaminterheléses szív mágneses rezonanciás vizsgálat alsó végtagi érszukületben szenvedo betegeken.

Patients with peripheral arterial disease often have coronary heart disease, as well. However, their assessment with classical noninvasive cardiology methods is often non-diagnostic or limited. The aim of this study was to analyze the feasibility and the risks of dobutamine stress cardiovascular MRI for cardiac evaluation of patients with peripheral arterial disease. 21 patients with peripheral artery disease (mean±SD age 64.3±7.7 years) were studied prospectively with dobutamine stress cardiovascular MRI. The protocol was completed by all of 21 patients. The target heart rate was attained in 95.2% of the studies. No serious adverse event occurred. The image quality scores (1-4) for all ventricular wall segments were high (median, interquartile range) (4 [4-4]). Five patients (23.8%) have inducible wall motion abnormality. Interobserver agreement was almost perfect for wall motion scores (κ = 0.87, p<0.0001). Dobutamine stress cardiovascular MRI is feasible with low risk for the cardiological assessment of patients with peripheral arterial disease.

Differentiation of acute and four-week old myocardial infarct with Gd(ABE-DTTA)-enhanced CMR.

BACKGROUND: Standard extracellular cardiovascular magnetic resonance (CMR) contrast agents (CA) do not provide differentiation between acute and older myocardial infarcts (MI). The purpose of this study was to develop a method for differentiation between acute and older myocardial infarct using myocardial late-enhancement (LE) CMR by a new, low molecular weight contrast agent.Dogs (n = 6) were studied in a closed-chest, reperfused, double myocardial infarct model. Myocardial infarcts were generated by occluding the Left Anterior Descending (LAD) coronary artery with an angioplasty balloon for 180 min, and four weeks later occluding the Left Circumflex (LCx) coronary artery for 180 min. LE images were obtained on day 3 and day 4 after second myocardial infarct, using Gd(DTPA) (standard extracellular contrast agent) and Gd(ABE-DTTA) (new, low molecular weight contrast agent), respectively. Triphenyltetrazolium chloride (TTC) histomorphometry validated existence and location of infarcts. Hematoxylin-eosin and Masson's trichrome staining provided histologic evaluation of infarcts. RESULTS: Gd(ABE-DTTA) or Gd(DTPA) highlighted the acute infarct, whereas the four-week old infarct was visualized by Gd(DTPA), but not by Gd(ABE-DTTA). With Gd(ABE-DTTA), the mean +/- SD signal intensity enhancement (SIE) was 366 +/- 166% and 24 +/- 59% in the acute infarct and the four-week old infarct, respectively (P < 0.05). The latter did not differ significantly from signal intensity in healthy myocardium (P = NS). Gd(DTPA) produced signal intensity enhancements which were similar in acute (431 +/- 124%) and four-week old infarcts (400 +/- 124%, P = NS), and not statistically different from the Gd(ABE-DTTA)-induced SIE in acute infarct. The existence and localization of both infarcts were confirmed by triphenyltetrazolium chloride (TTC). Histologic evaluation demonstrated coagulation necrosis, inflammation, and multiple foci of calcification in the four day old infarct, while the late subacute infarct showed granulation tissue and early collagen deposition. CONCLUSIONS: Late enhancement CMR with separate administrations of standard extracellular contrast agent, Gd(DTPA), and the new low molecular weight contrast agent, Gd(ABE-DTTA), differentiates between acute and late subacute infarct in a reperfused, double infarct, canine model.

Improved cardiorespiratory fitness following moderate exercise may encourage inactive people for doable and sustainable behavioral change.

BACKGROUND: Global physical inactivity pandemic is responsible for more than 5 million deaths annually through its effects on non-communicable diseases. This requires urgent intervention. The aim of this study was to investigate the associations of physical activity with cardiovascular fitness in a cross-sectional retrospective observational fashion. Data were collected for 21 years from 2530 healthy volunteers and athletes representing the entire spectrum of physical activity from the totally inactive sedentary persons to the highly trained national athletes. METHODS: Cardiac fitness was investigated echocardiographically, which is characterized by reduced resting heart rate (RHR), increased relative left ventricular muscular mass (rLVMM), improved left ventricular diastolic function (characterized by the ratio of early to late ventricular peak velocities, E/A) and peak exercise oxygen consumption. RESULTS: We found that even moderate exercise is associated with improved cardiac characteristics. With increasing exercise level, the RHR decreased from 69 to 63.3, 61.4, 58.6, 56.1, and 55.8/min in non-athletes, leisure athletes, lower class athletes, 2nd class athletes, 1st class athletes, and national athletes, respectively. While the rLVMM was increased from 64.6 to 70.7, 76.3, 78.5, 86.7, and 88.9 in the same groups. The E/A ratio also increased from 1.71 to 1.72, 1.85, 2.04 in the non-athletes, leisure athletes, lower class athletes, and 2nd class athletes, respectively, but then decreased to 1.92 and 1.98 in the 1st class athletes and national athletes. The largest exercise-induced improvement of cardiac fitness was observed between the inactive and the least active group, which did not increase further in the highly trained national athletes enduring up to 20 training hours per week. CONCLUSIONS: Our findings indicate that cardiac fitness can be improved by moderate exercise in sedentary persons. This information would help physicians to encourage inactive patients, who find physical exercise intimidating, for doable and sustainable behavioral change.

The MRI characteristics of the no-flow region are similar in reperfused and non-reperfused myocardial infarcts: an MRI and histopathology study in swine.

BACKGROUND: The no-flow region (NF) visualised by magnetic resonance imaging (MRI) in myocardial infarction (MI) has been explained as the product of reperfusion-injury-induced microvascular obstruction. However, a similar MRI phenomenon occurs in non-reperfused MI. Accordingly, our purpose was to compare the MRI and histopathologic characteristics of the NF in reperfused and non-reperfused MIs. METHODS: Reperfused (n = 7) and non-reperfused MIs (n = 7) were generated in swine by percutaneous balloon occlusion and microsphere embolisation techniques. Four days post-MI, animals underwent myocardial T2-mapping, early and serial late gadolinium enhancement MRI. MI and NF were compared between the models using the independent samples t test. Serial measurements were analysed using repeated measures analysis of variance. Triphenyltetrazolium chloride (TTC) macroscopic and microscopic histopathologic assessment was also performed. RESULTS: The MI size in the reperfused and non-reperfused groups was 17.1 ± 3.4 ml and 19.4 ± 8.1 ml, respectively (p = 0.090), in agreement with TTC assessment (p = 0.216; p = 0.484), and the NF size was 7.7 ± 2.4 ml and 8.1 ± 1.9 ml, respectively (P = 0.211). Compared to the reference 2-min post-contrast measurement, the NF size was significantly reduced at 20 min in the reperfused group and at 25 min in the non-reperfused group (both p < 0.001). Nevertheless, the NF was still detectable at 45 min after injection. No significant T2 difference was observed between the groups (p > 0.326). Histopathologic assessment revealed extensive calcification and hemosiderin deposition in the NF of the reperfused MI, but not in the non-reperfused MI. CONCLUSIONS: The NF in non-reperfused and reperfused MIs have similar characteristics on MRI despite the different pathophysiologic and underlying histopathologic conditions, indicating that the presence of the NF alone cannot differentiate between these two types of MI.

Evaluation of hyperdynamic resuscitation in 60% TBSA burn-injured sheep.

It has been suggested that hyperdynamic (HD) resuscitation improves outcomes. We hypothesized that initial HD resuscitation of burn injury using fluid and inotropes would improve metabolic function as indicated by base excess. We used an anesthetized ovine model of 60% TBSA full-thickness flame burn with delayed resuscitation started at 90 min after burn and continued for 8 h. Three groups (n = 6 each) were included: 1) HD defined as cardiac index (CI) of 1.5x baseline achieved by using Ringer's lactate alone (HD-Fluid); 2) Ringer's lactate and dobutamine (HD-Drug); and 3) Parkland Formula (Parkland) as a control group. Statistical analysis performed using analysis of variance and Tukey's HSD test. Significance accepted at P < 0.05. Higher CI was achieved in both HD-Fluid and HD-Drug groups, e.g., at 8 h the CI was 4.6 +/- 0.4 and 4.7 +/- 0.6 L/min/m respectively, as compared with Parkland 3.6 +/- 0.5 L/min/m. The net fluid balance (fluid infused - urine output) was similar in both Parkland and HD-Drug groups, which were 2.5x more in HD-Fluid (P = 0.001). The mean postburn urinary outputs were similar in both Parkland and HD-Drug groups, e.g., Parkland (0.9 +/- 0.08 mL/kg/h), HD-Drug (1.0 +/- 0.2 mL/kg/h) and increased in HD-Fluid (3.7 +/- 1.0 mL/kg/h; P = 0.0005). Base excess remained positive in both HD-Drug (+2.5 +/- 1 mmol/L) and Parkland (+1.5 +/- 1.7 mmol/L), and declined to -4.0 +/- 3.6 mmol/L in HD-Fluid group (P = 0.036). We conclude that there may be no benefit to using hyperdynamic regimens for the initial resuscitation of burn injury.

Hypotensive resuscitation of multiple hemorrhages using crystalloid and colloids.

Hypotensive resuscitation has been advocated as a better means to perform field resuscitation of penetrating trauma. Our hypothesis is that hypotensive resuscitation using either crystalloid or colloid provides equivalent or improved metabolic function while reducing the overall fluid requirement for resuscitation of hemorrhage. We compared hypotensive and normotensive resuscitation of hemorrhage using lactated Ringer's (LR) with hypotensive resuscitation using Hextend (Hex), 6% hetastarch in isotonic buffered saline. Instrumented conscious sheep were hemorrhaged in three separate bleeds, 25 mL/kg at T0 and 5 mL/kg at both T50 and T70. Resuscitation was started at T30 and continued until T180. Hypotensive resuscitation to a mean arterial pressure (MAP) of 65 mmHg was performed with LR or Hex using a closed-loop resuscitation (CLR) system for a LR-65 and Hex-65 treatment protocol. A control treatment protocol was resuscitation with LR to a MAP target of 90 mmHg, LR-90. All treatment protocols were successfully resuscitated to near target levels. Two animals in the hypotensive treatment protocols died during the second and third bleedings, one in the LR-65 and one in the Hex-65 treatment protocol. Mean infused volumes were 61.4 +/- 11.3, 18.0 +/- 5.9, and 11.6 +/- 1.9 mL/kg in the LR-90, LR-65, and Hex-65 treatments, respectively (*P < 0.05 versus LR-90). Mean minimum base excess (BE) values were +1.9 +/- 1.4, -5.8 +/- 4.3, and -5.9 +/- 4.0 mEq/L in the LR-90, LR-65, and Hex-65 treatments, respectively. Hypotensive resuscitation with LR greatly reduced volume requirements as compared with normotensive resuscitation, and Hex achieved additional volume sparing. However, trends toward lower BE values and the occurrence of deaths only in the hypotensive treatment protocols suggest that resuscitation to a target MAP of 65 mmHg may be too low for optimal outcomes.

Comparison of transfusion with DCLHb or pRBCs for treatment of intraoperative anemia in sheep.

Isoflurane-anesthetized sheep were transfused with packed red blood cells (pRBCs) or diaspirin cross-linked hemoglobin (DCLHb) for treatment of intraoperative hemorrhage. A rapid 15-min hemorrhage with lactated Ringer (LR) infusion maintained filling pressure at baseline and reduced blood hemoglobin (Hb) to ~5 g/dl. Sheep received 2 g/kg Hb, DCLHb (n = 6), or pRBCs (n = 7); control group received LR alone (n = 6). After 2 h, anesthesia was discontinued; sheep were monitored in the animal intensive care unit for 48 h. DCLHb expanded blood volume more, but increased total blood Hb less, than pRBCs. Lower Hb and increased methemoglobin resulted in lower arterial oxygen content compared with the pRBCs. DCLHb caused pulmonary hypertension (from 13 to 30 mmHg) and elevated filling pressure (from 6 to 15 mmHg). Cardiac outputs (CO) were similar for all groups during anesthesia; however, during recovery CO increased only in the LR and packed pRBCs groups. DCLHb may limit the reflex ability to increase CO after volume expansion. Hemodynamic effects of DCLHb may be exaggerated when infused after large-volume LR.

Infarct density distribution by MRI in the porcine model of acute and chronic myocardial infarction as a potential method transferable to the clinic.

To study the feasibility of a myocardial infarct (MI) quantification method [signal intensity-based percent infarct mapping (SI-PIM)] that is able to evaluate not only the size, but also the density distribution of the MI. In 14 male swine, MI was generated by 90 min of closed-chest balloon occlusion followed by reperfusion. Seven (n = 7) or 56 (n = 7) days after reperfusion, Gd-DTPA-bolus and continuous-infusion enhanced late gadolinium enhancement (LGE) MRI, and R1-mapping were carried out and post mortem triphenyl-tetrazolium-chloride (TTC) staining was performed. MI was quantified using binary [2 or 5 standard deviation (SD)], SI-PIM and R1-PIM methods. Infarct fraction (IF), and infarct-involved voxel fraction (IIVF) were determined by each MRI method. Bias of each method was compared to the TTC technique. The accuracy of MI quantification did not depend on the method of contrast administration or the age of the MI. IFs obtained by either of the two PIM methods were statistically not different from the IFs derived from the TTC measurements at either MI age. IFs obtained from the binary 2SD method overestimated IF obtained from TTC. IIVF among the three different PIM methods did not vary, but with the binary methods the IIVF gradually decreased with increasing the threshold limit. The advantage of SI-PIM over the conventional binary method is the ability to represent not only IF but also the density distribution of the MI. Since the SI-PIM methods are based on a single LGE acquisition, the bolus-data-based SI-PIM method can effortlessly be incorporated into the clinical image post-processing procedure.

Acute infarct selective MRI contrast agent.

To determine the infarct affinity of a low molecular weight contrast agent, Gd(ABE-DTTA), during the subacute phase of myocardial infarct (MI). Dogs (n = 7) were examined, using a closed-chest, reperfused MI model. MI was generated by occluding for 180 min the left anterior descending (LAD) coronary artery with an angioplasty balloon. DE-MRI images with Gd(ABE-DTTA) were obtained on days 4, 14, and 28 after MI. Control DE-MRI by Gd(DTPA) was carried out on day 27. T2-TSE images were acquired on day 3, 13 and 27. Triphenyltetrazolium chloride (TTC) histomorphometry validated postmortem the existence of infarct. Gd(ABE-DTTA) highlighted the infarct on day 4, but not at all on day 14 or on day 28, following MI. On day 4, the mean ± SD signal intensity (SI) of infarcted myocardium in the presence of Gd(ABE-DTTA) significantly differed from that of healthy myocardium (45 ± 6.0 vs. 10 ± 5.0, P < 0.05), but it did not on day 14 (11 ± 9.4 vs. 10 ± 5.7, P = NS), nor on day 28 (7 ± 1.5 vs. 7 ± 2.4, P = NS). The mean ± SD signal intensity enhancement (SIE) induced by Gd(ABE-DTTA) was 386 ± 165% on day 4, significantly different from mean SIE on day 14 (9 ± 20%), and from mean SIE on day 28 (12 ± 18%), following MI (P < 0.05). The last two mean values did not differ significantly (P = NS) from each other. As control, Gd(DTPA) was used and it did highlight the infarct on day 27, inducing a mean SIE value of 312 ± 40%. The mean SIE on day 3, 13, or 27 did not vary significantly (P = NS) on the T2-TSE images (114 ± 41%, 123 ± 41%, and 150 ± 79%, respectively). Post mortem, the existence of infarcts was confirmed by TTC staining. The infarct affinity of Gd(ABE-DTTA) vanishes in the subacute phase of scar healing, allowing its use for infarct age differentiation early on, immediately following the acute phase.

Determination of infarct size in ex vivo swine hearts by multidetector computed tomography using gadolinium as contrast medium.

OBJECTIVE: To demonstrate the feasibility of using multidetector computed tomography with gadolinium contrast (Gd-MDCT) for the quantification of myocardial infarct (MI). MATERIALS AND METHODS: MI was induced in male swine (n = 6). One week later, the animals received 0.2-mmol/kg gadopentetate dimeglumine and were sacrificed. On the excised hearts, Gd-MDCT with several tube voltages (80, 120, and 140 kV), late gadolinium enhancement MRI (LGE-MRI), and triphenyl-tetrazolium-chloride staining were then conducted. We used a 2-SD threshold for the CT images and several threshold limits (2, 3, 4, 5, 6 SD, and full width at half-maximum [FWHM]) for the LGE-MRI images to delineate the infarct area. Total infarct volume and infarct fraction of each heart were calculated. RESULTS: MI size measured by MDCT at 140 kV showed good correlation with the reference triphenyl-tetrazolium-chloride value. Applying an 80-kV tube voltage, however, significantly underestimated MI size. In our study, the LGE-MRI method, using the 6-SD threshold, provided the most accurate determination of MI size. LGE-MRI, using the 2- and 3-SD threshold limits, significantly overestimated infarct size. CONCLUSIONS: The Gd-MDCT technique has been found suitable for the evaluation of MI in an ex vivo experimental setting. Gd-MDCT has the ability to detect MI even at low kV settings, but accuracy is limited by a high image noise because of reduced photon flux.

Quantification of myocardial viability distribution with Gd(DTPA) bolus-enhanced, signal intensity-based percent infarct mapping.

INTRODUCTION: A substantial, common shortcoming of the currently used semiautomated techniques for the quantification of myocardial infarct with delayed enhancement magnetic resonance imaging is the assumption that the whole myocardial slab that corresponds to the hyperenhanced tomographic area is 100% nonviable. This assumption is, however, incorrect. To resolve this conflict, we have recently proposed the signal intensity percent-infarct mapping method and validated it in an ex vivo, canine experiment. The purpose of the current study has been the validation of the signal intensity percent-infarct mapping method in vivo, using a porcine model of reperfused myocardial infarct. METHODS: In swines (n=6), reperfused myocardial infarct was generated occluding for 90 min by an angioplasty balloon either the left anterior descending or the left circumflex coronary artery. To obtain DE images, Gd(DTPA) enhanced inversion-recovery fast gradient-echo acquisitions were carried out on day 28 after myocardial infarction. Scanning started 15 min after intravenous injection of 0.2 mmol/kg Gd(DTPA). At the end of the MRI session, the animal was sacrificed and 2,3,5-triphenyltetrazolium chloride staining was used to validate the existence and to determine the accurate size of the myocardial infarct. Tissue samples were taken and stained with hematoxylin-eosin and Masson's trichrome for histological assessment of the infarct and the periinfarct zone. The signal intensity percent-infarct mapping data were compared with corresponding data from the delayed enhancement images analyzed with SI(remote+2S.D.) thresholding, and with corresponding triphenyltetrazolium-chloride staining data using Friedman's repeated measure analysis of variance on ranks. RESULTS: The infarct volume determined by the triphenyltetrazolium chloride, SI(remote+2S.D.) and signal intensity percent-infarct mapping methods was 3.04 ml [2.74, 3.45], 13.62 ml [9.06, 18.45] and 4.27 ml [3.45, 6.33], respectively. Median infarct volume determined by SI(remote+2S.D.) significantly differed from that determined by triphenyltetrazolium chloride (P<.05). The Bland-Altman overall bias was 12.49% of the volume of the left ventricle. Median infarct volume determined by signal intensity percent-infarct mapping, however, did not differ significantly (NS) from that obtained by triphenyltetrazolium chloride. Signal intensity percent-infarct mapping yielded only a 1.99% Bland-Altman overall bias of the left ventricular volume. CONCLUSIONS: This in vivo study in the porcine reperfused myocardial infarct model demonstrates that signal intensity percent-infarct mapping is a highly accurate method for the determination of the extent of myocardial infarct. MRI images for signal intensity percent-infarct mapping are obtained with the pulse sequence of conventional delayed enhancement imaging and are acquired within clinically acceptable scanning time. This makes signal intensity percent-infarct mapping a practical method for clinical implementation.

Near-infrared spectroscopy-guided closed-loop resuscitation of hemorrhage.

BACKGROUND: Endpoint resuscitation has been suggested as a better means to resuscitate penetrating injury. We performed computer-controlled closed-loop resuscitation using invasive cardiac output (CO) or noninvasive skeletal muscle oxygen saturation (SkMusSO(2)) via near infrared spectroscopy (NIRS). METHODS: Conscious sheep received a 4.0-mm aortotomy and uncontrolled hemorrhage at t = 0 min (T0) while resuscitation started at T20 using lactated Ringer's solution. RESULTS: The aortotomy rapidly decreased the mean arterial pressure (MAP) to approximately 30 mm Hg and CO to 20% to 30% of baseline. The SkMusSO(2) endpoint group required only half as much fluid through 4 hours of resuscitation as the CO endpoint group (34.9 +/- 8.4 mL/kg vs. 63.1 +/- 9.4 mL/kg). CO and MAP were lower in the SkMusSO(2) group after T60. Mean infusion volumes were 180% and 100% of the bled volume collected at autopsy in the CO and SkMusSO(2) groups. Brain and muscle oxygenation and base excess were as high or higher in the CO endpoint group. CONCLUSION: Closed-loop resuscitation with either CO or SkMusSO(2) endpoints effectively performs fluid resuscitation of severe uncontrolled hemorrhagic shock. Limited resuscitation may achieve favorable clinical results with volumes less than recommended by Advanced Trauma Life Support guidelines.

Sleep environment and the risk of sudden infant death syndrome in an urban population: the Chicago Infant Mortality Study.

OBJECTIVE: To examine risk factors for sudden infant death syndrome (SIDS) with the goal of reducing SIDS mortality among blacks, which continues to affect this group at twice the rate of whites. METHODS: We analyzed data from a population-based case-control study of 260 SIDS deaths that occurred in Chicago between 1993 and 1996 and an equal number of matched living controls to determine the association between SIDS and factors in the sleep environment and other variables related to infant care. RESULTS: The racial/ethnic composition of the study groups was 75.0% black; 13.1% Hispanic white; and 11.9% non-Hispanic white. Several factors related to the sleep environment during last sleep were associated with higher risk of SIDS: placement in the prone position (unadjusted odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.7-3.4), soft surface (OR: 5.1; 95% CI: 3.1-8.3), pillow use (OR: 2.5; 95% CI: 1.5-4.2), face and/or head covered with bedding (OR: 2.5; 95% CI: 1.3-4.6), bed sharing overall (OR: 2.7; 95% CI: 1.8-4.2), bed sharing with parent(s) alone (OR: 1.9; 95% CI: 1.2-3.1), and bed sharing in other combinations (OR: 5.4; 95% CI: 2.8-10.2). Pacifier use was associated with decreased risk (unadjusted OR: 0.3; 95% CI: 0.2-0.5), as was breastfeeding either ever (OR: 0.2; 95% CI: 0.1-0.3) or currently (OR: 0.2; 95% CI: 0.1-0.4). In a multivariate model, several factors remained significant: prone sleep position, soft surface, pillow use, bed sharing other than with parent(s) alone, and not using a pacifier. CONCLUSIONS: To lower further the SIDS rate among black and other racial/ethnic groups, prone sleeping, the use of soft bedding and pillows, and some types of bed sharing should be reduced.

Isoflurane but not mechanical ventilation promotes extravascular fluid accumulation during crystalloid volume loading.

BACKGROUND: The combination of isoflurane anesthesia and mechanical ventilation reduces urinary output and promotes redistribution of a crystalloid bolus into the extravascular space. The authors hypothesized that mechanical ventilation rather than isoflurane causes this alteration. METHODS: The fate of a 25-ml/kg, 20-min, 0.9% saline fluid bolus was studied in four different experiments per sheep: while conscious and spontaneously ventilating (CSV), while conscious and mechanically ventilated (CMV), while anesthetized with isoflurane and mechanical ventilated (ISOMV), and while anesthetized with isoflurane and spontaneously ventilating (ISOSV). RESULTS: By calculations based on the indicator dilution and mass balance principles, plasma expansion was similar between protocols. Isoflurane but not mechanical ventilation reduced urinary output and increased interstitial fluid volume (P < 0.001): At 180 min, mean total urinary outputs were 15.6 +/- 2.1 and 15.9 +/- 2.9 ml/kg in the CSV and CMV protocols and 2.7 +/- 0.6 and 3.1 +/- 1.1 ml/kg in the ISOSV and ISOMV protocols, respectively. The net changes in extravascular volume, assumed to be interstitial fluid volume, were 8.6 +/- 3.3 and 8.1 +/- 3.1 ml/kg, and 22.5 +/- 1.5 and 22.1 +/- 1.6 ml/kg in the corresponding protocols. Volume kinetic analysis demonstrated extravascular fluid accumulation associated with isoflurane anesthesia similar to the calculated interstitial accumulation of 20.2 +/- 0.5 and 26.5 +/- 0.3 ml/kg in the ISOSV and ISOMV protocols, respectively. CONCLUSION: Isoflurane, but not mechanical ventilation, decreased urinary excretion and increased interstitial fluid volume. Volume kinetic analysis indicated "third-space" losses due to isoflurane. Perioperative fluid retention may be associated not only with surgical tissue manipulation, but with anesthesia per se.

Aplicación de la medicina legal en los derechos humanos / Legal medicine application in human wrights

Se analiza la aplicación de las Ciencia Forenses en el estudio de casos de derechos humanos, en personas que han sido víctimas de tortura física o psicológica. Enfatiza en el cuidado que se debe tener ante un certificado médico de defunción en una persona joven en ausencia de enfermedad y en el examen clínico y psicológico de la persona viva que ha sido torturada.