Tracheal fluid leakage in benchtop trials: comparison of static versus dynamic ventilation model with and without lubrication

Purpose: Longitudinal folds in tracheal tube (TT) cuffs cause leakage of pooled secretions past the tube cuff, and the most common in vitro method to test the efficacy of a new tube is a benchtop model using an artificial rigid trachea. This study compared the potential of a static and dynamic ventilation benchtop model and cuff lubrication in testing the tracheal sealing properties of a given TT cuff. Methods: Static trial Six brands of 7.5mm internal diameter (ID) cuffed TT (n=8) with high volume-low pressure cuffs were inflated in an artificial trachea (18mm ID) without and with lubrication. Dynamic trial The same tube cuffs, without lubrication, were subjected to positive pressure ventilation (PPV)+positive end-expiratory pressure (PEEP) of 5cmH2O or to PPV alone (without PEEP) or to PEEP alone (without PPV). Clear water (5ml) was placed above the tube cuff, and fluid leakage (ml) was measured up to 60min. Results: Gel lubrication, PEEP alone and PPV+PEEP completely prevented fluid leakage across the tube cuffs in all six TT brands tested within 60min when compared to the static unlubricated model (0% leak versus 100% leak; P<0.01). Fluid leakage in the static unlubricated model and the PPV group was 1.38-4.76ml and 0.23-4.47ml, respectively. Conclusion: Gel lubrication, PEEP alone, and PPV+PEEP in the benchtop model had a much stronger protective effect than PPV alone on fluid leakage. Studies testing the fluid sealing efficiency of tube cuffs might be more conclusive in a static benchtop model without lubrication than in a dynamic mode

Functional connectivity and amplitude of low-frequency fluctuations changes in people with complete subacute and chronic spinal cord injury.

After spinal cord injury (SCI), reorganization processes and changes in brain connectivity occur. Besides the sensorimotor cortex, the subcortical areas are strongly involved in motion and executive control. This exploratory study focusses on the cerebellum and vermis. Resting-state functional magnetic resonance imaging (fMRI) was performed. Between-group differences were computed using analysis of covariance and post-hoc tests for the seed-based connectivity measure with vermis and cerebellum as regions of interest. Twenty participants with complete SCI (five subacute SCI, 15 with chronic SCI) and 14 healthy controls (HC) were included. Functional connectivity (FC) was lower in all subjects with SCI compared with HC in vermis IX, right superior frontal gyrus (pFDR = 0.008) and right lateral occipital cortex (pFDR = 0.036). In addition, functional connectivity was lower in participants with chronic SCI compared with subacute SCI in bilateral cerebellar crus I, left precentral- and middle frontal gyrus (pFDR = 0.001). Furthermore, higher amplitude of low-frequency fluctuations (ALFF) was found in the left thalamus in individuals with subacute SCI (pFDR = 0.002). Reduced FC in SCI indicates adaptation with associated deficit in sensory and motor function. The increased ALFF in subacute SCI might reflect reorganization processes in the subacute phase

Mean kurtosis-Curve (MK-Curve) correction improves the test–retest reproducibility of diffusion kurtosis imaging at 3 T

Diffusion kurtosis imaging (DKI) is applied to gain insights into the microstructural organization of brain tissues. However, the reproducibility of DKI outside brain white matter, particularly in combination with advanced estimation to remedy its noise sensitivity, remains poorly characterized. Therefore, in this study, we investigated the variability and reliability of DKI metrics while correcting implausible values with a fit method called mean kurtosis (MK)-Curve. A total of 10 volunteers (four women; age: 41.4 ± 9.6 years) were included and underwent two MRI examinations of the brain. The images were acquired on a clinical 3-T scanner and included a T1-weighted image and a diffusion sequence with multiple diffusion weightings suitable for DKI. Region of interest analysis of common kurtosis and tensor metrics derived with the MK-Curve DKI fit was performed, including intraclass correlation (ICC) and Bland–Altman (BA) plot statistics. A p value of less than 0.05 was considered statistically significant. The analyses showed good to excellent agreement of both kurtosis tensor- and diffusion tensor-derived MK-Curve–corrected metrics (ICC values: 0.77–0.98 and 0.87–0.98, respectively), with the exception of two DKI-derived metrics (axial kurtosis in the cortex: ICC = 0.68, and radial kurtosis in deep gray matter: ICC = 0.544). Non-MK-Curve–corrected kurtosis tensor-derived metrics ranged from 0.01 to 0.52 and diffusion tensor-derived metrics from 0.06 to 0.66, indicating poor to moderate reliability. No structural bias was observed in the BA plots for any of the diffusion metrics. In conclusion, MK-Curve–corrected DKI metrics of the human brain can be reliably acquired in white and gray matter at 3 T and DKI metrics have good to excellent agreement in a test–retest setting

Functional connectivity and amplitude of low-frequency fluctuations changes in people with complete subacute and chronic spinal cord injury

After spinal cord injury (SCI), reorganization processes and changes in brain connectivity occur. Besides the sensorimotor cortex, the subcortical areas are strongly involved in motion and executive control. This exploratory study focusses on the cerebellum and vermis. Resting-state functional magnetic resonance imaging (fMRI) was performed. Between-group differences were computed using analysis of covariance and post-hoc tests for the seed-based connectivity measure with vermis and cerebellum as regions of interest. Twenty participants with complete SCI (five subacute SCI, 15 with chronic SCI) and 14 healthy controls (HC) were included. Functional connectivity (FC) was lower in all subjects with SCI compared with HC in vermis IX, right superior frontal gyrus (p$_{FDR}$ = 0.008) and right lateral occipital cortex (p$_{FDR}$ = 0.036). In addition, functional connectivity was lower in participants with chronic SCI compared with subacute SCI in bilateral cerebellar crus I, left precentral- and middle frontal gyrus (p$_{FDR}$ = 0.001). Furthermore, higher amplitude of low-frequency fluctuations (ALFF) was found in the left thalamus in individuals with subacute SCI (p$_{FDR}$ = 0.002). Reduced FC in SCI indicates adaptation with associated deficit in sensory and motor function. The increased ALFF in subacute SCI might reflect reorganization processes in the subacute phase

Osteoporosis in the lower extremities in chronic spinal cord injury.

STUDY DESIGN Cross-sectional study. OBJECTIVES To investigate the effect of chronic motor complete spinal cord injury (SCI) and sex on bone densitometry parameters of the hip, femoral neck, tibial epiphysis, and diaphysis and on long bone fractures. SETTING SCI rehabilitation center. METHODS Women and men with long-term (≥7 years) motor complete SCI were compared with able-bodied women and men. Dual-energy X-ray absorptiometry was used to assess bone densitometry parameters at the hip and femoral neck, whereas peripheral quantitative computed tomography was used for the tibial epiphysis and diaphysis. RESULTS The data of 18 women and 25 men with SCI with a mean age of 54.7 ± 12.4 and 53.5 ± 8.6 years, respectively, were analyzed. As reference groups, 74 able-bodied women and 46 men with a mean age of 51.0 ± 13.1 and 50.9 ± 11.2 years were evaluated. Most bone densitometry values were significantly (p ≤ 0.033) lower in the SCI compared with the reference groups, including total bone mineral density at the distal tibial epiphysis (-58.0% in SCI women and -53.6% in SCI men). Fracture rates per 100 patient-years were 3.17 and 2.66 in women and men with SCI compared with 0.85 and 0.21 in able-bodied women and men, respectively. CONCLUSIONS Compared with able-bodied women and men, individuals with chronic motor complete SCI showed considerably lower bone densitometry values and a higher historical fracture rate. These findings support the need for preventative and therapeutic strategies against bone loss in individuals with SCI

Exercise Capacity, Functioning and Quality of Life 12 Weeks after Traumatic Thoracic Spinal Cord Injury

Background. A spinal cord injury (SCI) leads to patho-physiological changes that can affect physical and psychological performance. The aim of this observational study was to evaluate the relationship between exercise capacity, functioning and quality of life in patients 12 weeks after traumatic paraplegia participating in early rehabilitation. Material and methods. 13 patients participated in this study and performed cardio-pulmonary exercise testing (CPET) on an arm-crank ergometer to determine peak exercise capacity (VO2peak). Data from the spinal cord independence measure (SCIM) were used to assess different areas of functioning. The 12-item short form survey (SF12) questionnaire was applied to measure quality of life. Spearman correlations were used to relate VO2peak with SCIM data and results from the SF12 questionnaire. Results. VO2peak ranged between 12.6 and 28.1 ml/kg/min. A significant relationship was found between VO2peak and the physical component of the SF12 questionnaire, whereas no correlations were found with either SCIM sub or total score, or with the mental component or the total score of the SF12 questionnaire. Conclusions. 1. Patients with traumatic paraplegia showed fair to average exercise capacity after 12 weeks of early rehabilitation. 2. A significant relationship between VO2peak and subjectively rated physical fitness exists at this time point. 3. The implementation of an individual fitness program tailored to the patients' needs based on CPET results is highly recommended in order to improve functioning and quality of life

Massive aspiration past the tracheal tube cuff caused by closed trachael suction system

Background: Aspiration past the tracheal tube cuff has been recognized to be a risk factor for the development of ventilator-associated pneumonia (VAP). This study investigated the effect of closed tracheal suctioning on aspiration of fluid past the tracheal tube cuff in an in vitro benchtop model. Methods: High-volume low pressure tube cuffs of 7.5 mm internal diameter (ID) were placed in a 22 mm ID artificial trachea connected to a test lung. Positive pressure ventilation (PPV) with 15 cm H(2)O peak inspiratory pressure and 5 cm H(2)O positive end-expiratory pressure (PEEP) was used. A closed tracheal suction system (CTSS) catheter (size 14Fr) was attached to the tracheal tube and suction was performed for 5, 10, 15, or 20 seconds under 200 or 300 cm H(2)O suction pressures. Amount of fluid (mL) aspirated along the tube cuff and the airway pressure changes were recorded for each suction procedure. Fluid aspiration during different suction conditions was compared using Kruskal-Wallis and Mann-Whitney test (Bonferroni correction [α = .01]). Results: During 10, 15, and 20 seconds suction, airway pressure consistently dropped down to -8 to -13 cm H(2)O (P < .001) from the preset level. Fluid aspiration was never observed under PPV + PEEP but occurred always during suctioning. Aspiration along the tube cuff was higher with -300 cm H(2)O than with -200 cm H(2)O suction pressure (P < .001) and was much more during 15 and 20 seconds suction time as compared to 5seconds (P < .001). Conclusion: Massive aspiration of fluid occurs along the tracheal tube cuff during suction with the closed tracheal suction system

A novel algorithm for detecting active propulsion in wheelchair users following spinal cord injury

Physical activity in wheelchair-bound individuals can be assessed by monitoring their mobility as this is one of the most intense upper extremity activities they perform. Current accelerometer-based approaches for describing wheelchair mobility do not distinguish between self- and attendant-propulsion and hence may overestimate total physical activity. The aim of this study was to develop and validate an inertial measurement unit based algorithm to monitor wheel kinematics and the type of wheelchair propulsion (self- or attendant-) within a "real-world" situation. Different sensor set-ups were investigated, ranging from a high precision set-up including four sensor modules with a relatively short measurement duration of 24 h, to a less precise set-up with only one module attached at the wheel exceeding one week of measurement because the gyroscope of the sensor was turned off. The "high-precision" algorithm distinguished self- and attendant-propulsion with accuracy greater than 93% whilst the long-term measurement set-up showed an accuracy of 82%. The estimation accuracy of kinematic parameters was greater than 97% for both set-ups. The possibility of having different sensor set-ups allows the use of the inertial measurement units as high precision tools for researchers as well as unobtrusive and simple tools for manual wheelchair users

Changes in Strength, Sensation, and Prehension in Acute Cervical Spinal Cord Injury: European Multicenter Responsiveness Study of the GRASSP

Objective. To investigate the internal and external responsiveness and recovery profiles of the Graded Redefined Assessment of Strength, Sensibility, and Prehension (GRASSP) instrument in revealing changes in upper limb function within the first year following cervical spinal cord injury (SCI). Method. A European prospective, longitudinal, multicenter study assessing the GRASSP at 1, 3, 6, and 12 months after cervical SCI. Subtests of GRASSP were compared to the upper extremity motor (UEMS) and light touch scores (LT) according to the International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI), the Spinal Cord Independence Measure self-care subscore (SCIM-SS), as well as a clinician-rated outcome measure (CROM) of clinical relevance. Data were analyzed for GRASSP responsiveness and recovery rate over time. Results. Seventy-four participants entered the study. GRASSP subtests proved responsive (standardized response mean [SRM] ranged from 0.79 to 1.48 for strength, 0.50 to 1.03 for prehension, and 0.14 to 0.64 for sensation) between all examination time points. In comparison, UEMS and LT showed lower responsiveness (SRM UEMS ranged from 0.69 to 1.29 and SRM LT ranged from 0.30 to -0.13). All GRASSP subtests revealed significant, moderate-to-excellent correlations with UEMS, LT, and SCIM-SS at each time point, and changes in GRASSP subtests were in accordance with the CROM. GRASSP prehension and motor recovery was largest between 1 and 3 months. Conclusion. The GRASSP showed excellent responsiveness, detecting distinct changes in strength and prehension relating to the severity of cervical SCI. It detected clinically significant changes complimentary to the ISNCSCI and SCIM-SS assessments

Novel Sensor Technology To Assess Independence and Limb-Use Laterality in Cervical Spinal Cord Injury

After spinal cord injury (SCI), levels of independence are commonly assessed with standardized clinical assessments. However, such tests do not provide information about the actual extent of upper limb activities or the impact on independence of bi- versus unilateral usage throughout daily life following cervical SCI. The objective of this study was to correlate activity intensity and laterality of upper extremity activity measured by body-fixed inertial measurement units (IMUs) with clinical assessment scores of independence. Limb-use intensity and laterality of activities performed by the upper extremities was measured in 12 subjects with cervical SCI using four IMUs (positioned on both wrists, on the chest, and on one wheel of the wheelchair). Algorithms capable of reliably detecting self-propulsion and arm activity in a clinical environment were applied to rate functional outcome levels, and were related to clinical independence measures during inpatient rehabilitation. Measures of intensity of upper extremity activity during self-propulsion positively correlated (p < 0.05, r = 0.643) with independence measures related to mobility. Clinical measures of laterality were positively correlated (p < 0.01, r = 0.900) with laterality as measured by IMUs during "daily life," and increased laterality was negatively correlated (p < 0.01, r = -0.739) with independence. IMU sensor technology is sensitive in assessing and quantifying upper limb-use intensity and laterality in human cervical SCI. Continuous and objective movement data of distinct daily activities (i.e., mobility and day-to-day activities) can be related to levels of independence. Therefore, IMU sensor technology is suitable not only for monitoring activity levels during rehabilitation (including during clinical trials) but could also be used to assess levels of participation after discharge