Rotational Thromboelastometry-Guided Transfusion Protocol to Reduce Allogeneic Blood Transfusion in Proximal Aortic Surgery With Deep Hypothermic Circulatory Arrest.

OBJECTIVES: To determine the impact of a rotational thromboelastometry (ROTEM)-guided transfusion protocol on the use of blood products, patient outcomes, coagulation factor concentrates, and costs. DESIGN: A single-center retrospective cohort study. SETTING: A tertiary university hospital. PATIENTS: Adults undergoing proximal aortic surgery with deep hypothermic circulatory arrest. INTERVENTION: ROTEM-guided transfusion protocol compared with clinically-guided transfusion. MEASUREMENTS AND MAIN RESULTS: Two hundred seventeen patients were included; seventy-one elective and 24 emergency patients in the clinically-guided group, and 59 elective and 63 emergency patients in the ROTEM-guided transfusion protocol group. In the ROTEM-guided transfusion protocol group, a significant reduction in transfusion of red blood cells (5 [3-8] v 2 [0-4], p < 0.001), platelet concentrate (2 [2-3] v 1 [1-2], p < 0.001), and plasma (1,980 mL [1,320-3,300] v 800 mL [0-1,000], p < 0.001) was seen in elective surgery. Emergency patients received fewer red blood cells (7 [5-10] v 5 [2-10], p = 0.040), platelet concentrate (3 [2-4] v 2 [2-3], p = 0.023), and plasma (3,140 mL [1,980-3,960] v 1,000 mL [0-1,400], p < 0.001). Prothrombin complex concentrate and fibrinogen concentrate were increased significantly in elective and emergency patients. The surgical reexploration for bleeding rate was decreased in elective patients 33.8% v 5.1%. CONCLUSION: The implementation of a ROTEM-guided transfusion protocol might have the potential to decrease blood product transfusion and may improve patient outcomes.

Delineation of the mechanisms of tendon gliding resistance within the carpal tunnel.

BACKGROUND: Forceful, high-velocity, and repetitive manual hand tasks contribute to the onset of carpal tunnel syndrome. This study aimed to isolate and identify mechanisms that contribute to tendon gliding resistance in the carpal tunnel. METHODS: Eight human cadaver hands (four pairs) were used. Tendon gliding resistance (force, energy, and stiffness) was measured under different conditions: with intact and with divided subsynovial connective tissue, at 2mm/s and 60mm/s tendon excursion velocity, and with and without relaxation time before tendon excursion. RESULTS: Subsynovial connective tissue stretching substantially contributed to increased gliding resistance force and energy during higher tendon excursion velocities, and subsynovial connective tissue stiffening was observed. Poroelastic properties of the tendon (and possibly the subsynovial connective tissue) also appear to be involved because relaxation time significantly increased gliding resistance force and energy (P<0.01), and the difference in energy and force between high- and low-velocity tendon excursions increased with relaxation time (P=0.01 and P<0.01). Lastly, without relaxation time, no difference in force and energy was observed (P=0.06 and P=0.60), suggesting contact friction. INTERPRETATION: These findings are consistent with the hypothesis that the mechanics of tendon motion within the carpal tunnel are affected by the integrity of the subsynovial connective tissue. While not tested here, in carpal tunnel syndrome this tissue is known to be the fibrotic, thickened, and less-fluid-permeable. An extrapolation of our findings suggests that these changes in the subsynovial connective tissue of carpal tunnel syndrome patients could increase contact friction and carpal tunnel pressure.

Multidimensional ultrasound imaging of the wrist: Changes of shape and displacement of the median nerve and tendons in carpal tunnel syndrome.

Dynamics of structures within the carpal tunnel may alter in carpal tunnel syndrome (CTS) due to fibrotic changes and increased carpal tunnel pressure. Ultrasound can visualize these potential changes, making ultrasound potentially an accurate diagnostic tool. To study this, we imaged the carpal tunnel of 113 patients and 42 controls. CTS severity was classified according to validated clinical and nerve conduction study (NCS) classifications. Transversal and longitudinal displacement and shape (changes) were calculated for the median nerve, tendons and surrounding tissue. To predict diagnostic value binary logistic regression modeling was applied. Reduced longitudinal nerve displacement (p≤ 0.019), increased nerve cross-sectional area (p≤ 0.006) and perimeter (p≤ 0.007), and a trend of relatively changed tendon displacements were seen in patients. Changes were more convincing when CTS was classified as more severe. Binary logistic modeling to diagnose CTS using ultrasound showed a sensitivity of 70-71% and specificity of 80-84%. In conclusion, CTS patients have altered dynamics of structures within the carpal tunnel.

The effect of tendon excursion velocity on longitudinal median nerve displacement: differences between carpal tunnel syndrome patients and controls.

The subsynovial connective tissue (SSCT) is a viscoelastic structure connecting the median nerve (MN) and the flexor tendons in the carpal tunnel. Increased strain rates increases stiffness in viscoelastic tissues, and thereby its capacity to transfer shear load. Therefore, tendon excursion velocity may impact the MN displacement. In carpal tunnel syndrome (CTS) the SSCT is fibrotic and may be ruptured, and this may affect MN motion. In this study, ultrasonography was performed on 14 wrists of healthy controls and 25 wrists of CTS patients during controlled finger motions performed at three different velocities. Longitudinal MN and tendon excursion were assessed using a custom speckle tracking algorithm and compared across the three different velocities. CTS patients exhibited significantly less MN motion than controls (p ≤ 0.002). While in general, MN displacement increased with increasing tendon excursion velocity (p ≤ 0.031). These findings are consistent with current knowledge of SSCT mechanics in CTS, in which in some patients the fibrotic SSCT appears to have ruptured from the tendon surface.

Altered median nerve deformation and transverse displacement during wrist movement in patients with carpal tunnel syndrome.

RATIONALE AND OBJECTIVES: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. Strong pinch or grip with wrist flexion has been considered a risk factor for CTS. Studying median nerve displacement during wrist movements may provide useful information about median nerve kinematic changes in patients with CTS. The purpose of this study was to evaluate the deformability and mobility of the median nerve in patients with CTS compared to healthy subjects. MATERIALS AND METHODS: Dynamic ultrasound images were obtained in 20 affected wrists of 13 patients with CTS. Results were compared to complementary data obtained from both wrists of 10 healthy subjects reported in a previous study. Shape and position of initial and final median nerve were measured and analyzed for six defined wrist movements. The deformation ratios for each movement were defined as the median nerve area, perimeter, and circularity of the final position normalized by respective values assessed in the initial position. The median nerve displacement vector and magnitude were also calculated. RESULTS: The deformation ratio for circularity was significantly less in patients with CTS compared to healthy subjects during wrist flexion (P < .05). The mean vector of median nerve displacement during wrist flexion was significantly different between patients with CTS and healthy subjects (P < .05). The displacement magnitude of the median nerve was found to be less in patients with CTS compared to healthy subjects during most movements, with the exception of wrist extension with fingers extended. CONCLUSIONS: Patients with CTS differ from normal subjects with regard to mobility and deformability of the median nerve.

Transverse ultrasound assessment of median nerve deformation and displacement in the human carpal tunnel during wrist movements.

The symptoms of carpal tunnel syndrome, a compression neuropathy of the median nerve at the wrist, are aggravated by wrist motion, but the effect of these motions on median nerve motion are unknown. To better understand the biomechanics of the abnormal nerve, it is first necessary to understand normal nerve movement. The purpose of this study was to evaluate the deformation and displacement of the normal median nerve at the proximal carpal tunnel level on transverse ultrasound images during different wrist movements, to have a baseline for comparison with abnormal movements. Dynamic ultrasound images of both wrists of 10 asymptomatic volunteers were obtained during wrist maximal flexion, extension and ulnar deviation. To simplify the analysis, the initial and final shape and position of the median nerve were measured and analyzed. The circularity of the median nerve was significantly increased and the aspect ratio and perimeter were significantly decreased in the final image compared with the first image during wrist flexion with finger extension, wrist flexion with finger flexion and wrist ulnar deviation with finger extension (p < 0.01). There were significant differences in median nerve displacement vector between finger flexion, wrist flexion with finger extension and wrist ulnar deviation with finger extension (all p's < 0.001). The mean amplitudes of median nerve motion in wrist flexion with finger extension (2.36 ± 0.79 normalized units [NU]), wrist flexion with finger flexion (2.46 ± 0.84 NU) and wrist ulnar deviation with finger extension (2.86 ± 0.51 NU) were higher than those in finger flexion (0.82 ± 0.33 NU), wrist extension with finger extension (0.77 ± 0.46 NU) and wrist extension with finger flexion (0.81 ± 0.58 NU) (p < 0.0001). In the normal carpal tunnel, wrist flexion and ulnar deviation could induce significant transverse displacement and deformation of the median nerve.

The effect of low- and high-velocity tendon excursion on the mechanical properties of human cadaver subsynovial connective tissue.

Fibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel is the most common histological finding in carpal tunnel syndrome (CTS). Fibrosis may result from damaged SSCT. Previous studies found that with low-velocity (2 mm/s), tendon excursions can irreversibly damage the SSCT. We investigated the effect of tendon excursion velocity in the generation of SSCT damage. Nine human cadaver wrists were used. Three repeated cycles of ramp-stretch testing were performed simulating 40%, 60%, 90%, and 120% of the middle finger flexor tendon superficialis physiological excursion with an excursion velocity of 60 mm/s. Energy and force were calculated and normalized by values obtained in the first cycle for each excursion level. Data were compared with low-velocity excursion data. For high-velocity excursions, a significant drop in the excursion energy ratio was first observed at an excursion level of 60% physiological excursion (p < 0.024) and that for low-velocity excursions was first observed at 90% physiological excursion (p < 0.038). Furthermore, the energy ratio was lower at 60% for high velocities (p ≤ 0.039). Increasing velocity lowers the SSCT damage threshold. This finding may be relevant for understanding the pathogenesis of SSCT fibrosis, such as that accompanying CTS, and a relationship with occupational factors.

Dynamic sonographic measurements at the carpal tunnel inlet: reliability and reference values in healthy wrists.

INTRODUCTION: Reliability and reference values are not well-established for most dynamic sonographic measurements of the median nerve (MN) and flexor tendons that may be used for diagnosing carpal tunnel syndrome (CTS). METHODS: Wrists of 20 healthy participants were imaged using ultrasound. Cines of the carpal tunnel inlet were acquired during hand motion. Based on shape and displacement measurements, intra- and interrater reliability and reference values were calculated. RESULTS: Intraclass correlation coefficients (ICCs) for measurements of the MN and most flexor tendons were ≥0.51 for shape parameters and ≥0.71 for displacement parameters. During motion, the MN flattened with ulnar movement, tendons became more circular, and flexor tendons of corresponding fingers moved toward each other. CONCLUSION: Shape and displacement measurements of the MN and most flexor tendons had reliability results ranging from moderate to excellent. The reference values may be useful for the diagnosis of CTS.

Maternal psychosocial outcome after early onset preeclampsia and preterm birth.

OBJECTIVE: To evaluate the impact of severe, early onset preeclampsia on long-term maternal psychosocial outcome after preterm birth. METHODS: Women with severe, early onset preeclampsia before 32 weeks' gestation (cases) admitted in a tertiary university referral center between 1993 and 2004, and women with preterm delivery without preeclampsia (controls), matched for age, parity, gestational age at delivery, ethnicity, and year of delivery. Women who consented to participation received three questionnaires in 2008 concerning depression (Zung Depression Scale: score range 0-20; 20 items with 2-point frequency scale: no = 0 and yes = 1), posttraumatic stress symptoms (Impact of Event Scale: score range 0-75; 15 items with 4-point frequency scale: not at all = 0, rarely = 1, sometimes = 3 and often = 5. Scores > 19 are regarded as high symptom levels), and social aspects (Social Readjustment Rating Scale: selection of six items concerning relational aspects with husband/partner, employer, or future family planning). RESULTS: Included in the study were 104 cases and 78 controls (response rate 79% and 58%, respectively). There was no difference in depression scores between cases (5.4 ± 4.0) and controls (5.4 ± 4.3). Patients with severe, early onset preeclampsia had significantly higher scores of posttraumatic stress symptoms (28.7 ± 8.6 vs. 25.7 ± 7.9). The majority of women among both cases and controls had high-posttraumatic stress symptom levels (88% vs. 79%). No differences could be found in relational aspects. CONCLUSION: Women with preterm birth due to severe, early onset preeclampsia experience more often posttraumatic stress symptoms on average 7 years after the pregnancy compared to women with preterm birth without preeclampsia.