Reproducibility and responsiveness of heart rate indexes to assess wheeling efficiency in patients with spinal cord injuries.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To measure the reproducibility and responsiveness of heart rate indexes in measuring energy expenditure during wheelchair locomotion of adults with spinal cord injury (SCI). SETTING: SARAH Rehabilitation Hospital Network-Brasilia, Brazil. METHODS: The study consecutively enrolled 35 individuals with SCI. Volunteers propelled their wheelchairs at a self-selected and comfortable velocity around a circular track. The first assessment day was a responsiveness study, in which three tests were performed, with the wheelchair weight increased randomly during the last two tests. On the second assessment day, the test was conducted without extra weight (that is, baseline conditions) for reproducibility analyses. RESULTS: All indexes demonstrated reproducibility on all statistical analyses. The Propulsion Cardiac Cost Index (PCCI) had a lower variation coefficient than the Physiological Cost Index (PCI; 8.5%, 95% confidence interval (CI) 5.8-11.2 vs 24.2%, 95% CI 16.0-32.4) and lower effect size than the Total Heart Beat Index (THBI; 0.16 vs 0.26). The PCCI also had the best responsiveness results on all statistical tests. The PCCI correlation was the largest (r=0.63, P<0.01, 95% CI 0.43-0.83, followed by PCI (r=0.53, P<0.01, 95% CI 0.34-0.72) and then the THBI (r=0.50, P<0.01, 95% CI 0.29-0.71). CONCLUSIONS: All three indexes were reproducible and responsive. However, the PCCI gave better statistical results. This index may be useful in functional diagnosis and follow-up of rehabilitation.

Validity of heart rate indexes to assess wheeling efficiency in patients with spinal cord injuries.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To validate heart rate (HR) indexes for the evaluation of energy expenditure during wheelchair propulsion in people with spinal cord injury (SCI). SETTING: SARAH Rehabilitation Hospital Network-Brasilia, Brazil. METHODS: Forty-eight men aged 29.0±7.8 years with a SCI between C6 and L3 causing complete motor impairment were enrolled in the study. The assessment consisted of 5 min of rest while seated in the wheelchair, followed by 5 min of wheelchair propulsion at a self-selected comfortable speed. The main outcomes measured were oxygen consumption, HR, physiological cost index (PCI), total heart beat index (THBI) and propulsion cardiac cost index (PCCI). RESULTS: Using oxygen uptake as gold standard, the highest correlations were found between this and PCCI (r=0.59, P<0.001, 95% confidence interval (CI) 0.36-0.75) and THBI (r=0.58, P<0.001, 95% CI 0.36-74.0), independently of the injury level. The PCI had the lowest correlation coefficient (r=0.38, P<0.01, 95% CI 0.11-0.60). Spearman correlation analysis showed that the indexes mostly associated with lesion level were PCCI (ρ=-0.531; P<0.001; 95% CI -0.708 to -0.291) and THBI (ρ=-0.524; P<0.001; 95% CI -0.704 to -0.282). CONCLUSIONS: Both THBI and PCCI seem to be valid measures for assessing energy expenditure. Both indexes showed a coherent correlation with the spinal injury level.

Effect of graded water immersion on vital capacity and plasma volume in patients with cervical spinal cord injury.

STUDY DESIGN: A case-control study was conducted. OBJECTIVE: The aim of the study was to test the hypothesis that the increase in hydrostatic pressure on the abdominal wall may be the major determinant of vital capacity (VC) improvement in tetraplegic subjects during water immersion, despite the blood volume shifts from the legs and abdomen to the thorax. SETTING: The study was carried out in the Rehabilitation Center, Brasília/DF, Brazil. METHODS: In total, 11 men with tetraplegia (complete motor lesion, C4-7, 30.4 years old) and 12 healthy controls were studied. Hematocrit level and spirometry values were obtained on dry land and at each level of immersion (the pelvis, xiphoid and neck). RESULTS: Baseline spirometry value of tetraplegic subjects showed reduced VC (53.3+/-17.4% of predicted), whereas all control subjects had >80% of predicted values. Neither group showed significant changes in VC at the pelvic and xiphoid levels of immersion. In tetraplegic subjects, VC increased by 27.2% at the neck level (+/-25.8, P<0.008), whereas in healthy subjects it decreased by 6.3% (+/-5.0, P<0.008). Both groups showed significantly increased inspiratory capacity only when immersed to the neck. Hematocrit level of tetraplegic subjects fell significantly with immersion to the xiphoid and neck levels (P<0.017), which occurred in controls only at the xiphoid level (P<0.017). CONCLUSIONS: Hydrostatic compression may be the main contributor to improving VC in tetraplegic subjects immersed in water. This improvement occurs despite increased plasma volume during immersion.

Maximal static mouth respiratory pressure in spinal cord injured patients: correlation with motor level.

STUDY DESIGN: Transversal. OBJECTIVES: The few studies concerning maximal static mouth respiratory pressures in patients with spinal cord lesions suggest a marked reduction. We studied the correlation of these parameters with the motor level of injury. SETTING: Rehabilitation Center, Brasília/DF, Brazil. METHODS: One hundred and thirty-one patients with traumatic spinal cord injury (C4-L3) were recruited. The participants were assessed by standard spirometry and maximal static mouth respiratory pressure. RESULTS: Forced vital capacity was most reduced in tetraplegics (subgroup C4-C5, 49%+/-25 predicted) and increase successively for each descending subgroup (C6-C8, 61%+/-22 predicted; T1-T6, 70%+/-15 predicted), becoming normal in low paraplegia (T7-L3, 84%+/-15 predicted). There is no evidence of an obstructive disturbance throughout all groups. The lowest average percent predicted of maximal static inspiratory pressure (MIP) was in the subgroup C4-C5 (50%+/-23). The average percent predicted of maximal static expiratory pressure (MEP) improved from 19%+/-14 in the C4-C5 subgroup to 51%+/-19 for T7-L3 subgroup. The average percent predicted of all participants for MIP was 74%+/-30 and for MEP was 37%+/-21. In patients with complete motor lesion, the correlation with the level of injury was stronger for MEP (r=0.81, P<0.0001; r (2)=0.65) than for MIP (r=0.62, P=0.004; r (2)=0.38). No correlation was found among incomplete motor lesion patients. CONCLUSIONS: The linear regression equations for the relationship of percent predicted MIP or MEP to level of injury are applicable only to complete motor lesions and may be useful to establish normative association between them.

Cholinergic bronchomotor tone and airway caliber in tetraplegic patients.

STUDY DESIGN: Case-control study. OBJECTIVES: To evaluate the resting airway caliber in subjects with tetraplegia; to define the participation of cholinergic innervation in this condition; and to determine if baclofen modifies this pattern. SETTING: A rehabilitation hospital, Brasília, Brazil. METHODS: We studied 18 tetraplegic patients, with complete motor loss between C4 and C8, and 18 healthy control subjects by measuring airway conductance, before and after inhaled ipratropium bromide. RESULTS: At baseline, the pulmonary function parameters revealed mild-to-moderate restrictive impairment in tetraplegic patients as defined by decreases in total lung capacity and predicted percent of slow vital capacity. The average baseline specific airway conductance (sGaw) was less in tetraplegic patients (0.25+/-0.11) than in the control group (0.41+/-0.10 l/s/cm H(2)O) (P<0.0001). All patients had improved post-bronchodilator sGaw >or=40% compared with only four of the 18 controls (P<0.001). The average increase for tetraplegic patients was 235% (+/-93) versus 25% (+/-24) for controls (P<0.0001). Analysis of variance for repeated measurements showed significant difference in sGaw between the control and spinal cord injury (SCI) groups (P<0.0001) following bronchodilator challenge, but found no difference for total gas volume. No difference for mean basal sGaw and bronchodilator challenge was encountered comparing tetraplegic patients using baclofen to those not using it. CONCLUSIONS: Cervical SCI patients have a reduced baseline conductance compared to controls. Marked improvement occurs after an inhaled anticholinergic drug. This behavior was not affected by the use of baclofen. The study adds support to the hypothesis of an increased cholinergic bronchomotor tone in tetraplegic patients.

Neuronal counting and parasympathetic dysfunction in the hearts of chronically Trypanosoma cruzi infected rats

Dez ratos machos Wistar cronicamente infectados pelas cepas Colombiana, Sao Felipe (12SF), e Y do Trypanosoma cruzi, foram submetidos, apos 8 meses de infeccao, juntamente com dez animais controles, ao teste da resposta bradicardica barorreflexa pela injecao endovenosa de fenilefrina. Seis ratos chagasicos exibiram disfuncao cardiaca parassimpatica, caracterizada pela depressao do indice da resposta bradicardica barorreflexa. Embora o estudo histologico dos coracoes chagasicos mostrasse lesoes dos ganglios atriais, a contagem dos neuronios em cortes seriados, nao apresentou reducao numerica significativa dos mesmos.

Lesöes cardíacas em ratos Wistar inoculados com diferentes cepas do Trypanosoma cruzi / Cardiac lesions in Wistar rats infected with different strains of Trypanosoma cruzi

Ratos albinos Wistar infectados com diferentes inóculos das cepas Y, Colombiana (COL) e Säo Felipe (12SF) do Trypanosoma cruzi desenvolveram parasitemia elevada entre 14 e 21 dias, a qual tornou-se desprezível ou desapareceu completamente ao final da 4ª semana. As lesöes do coraçäo foram avaliadas, semiquantitativamente, pelo sistema de "scores", conforme a intensidade e a extensäo da inflamaçäo, nas diferentes estruturas do órgäo, tendo sido observado que: a) na fase inicial (aguda) da infecçäo, os animais mortos espontaneamente ou em conseqüência do acidente anestésico apresentaram cardite de intensidade moderada a acentuada, näo havendo diferença em relaçäo as cepas utilizadas; as diferentes estruturas do coraçäo estavam uniformemente comprometidas; b) na fase crônica da infecçäo observou-se cardite de grau leve a moderado e as lesöes foram mais freqüentes e intensas quanto maior o inóculo empregado; no entanto, inóculos baixos só produziram lesöes quando a cepa utilizada foi a Colombiana. Trombose mural nos átrios e dilataçäo da ponta do ventrículo esquerdo foram observadas em 20% dos animais, independetemente da cepa. Na fase crônica 15% dos animais apresentaram miocardite crônica com fibrose, associada a hipertrofia das miocélulas. Os AA confirmam ser o rato albino suscetível a infeccäo chagásica e, portanto, um modelo útil no estudo das manifestaçöes cardíacas da Doença de Chagas