Biomarkers of cardiometabolic health are associated with body composition characteristics but not physical activity in persons with spinal cord injury

Objective: To examine (i) the associations between physical activity dimensions, cardiorespiratory fitness and body composition and, (ii) the associations between physical activity dimensions, cardiorespiratory fitness, body composition and biomarkers of cardiometabolic health in persons with spinal cord injury (SCI).

Methods: A cross-sectional prospective cohort study with 7-day follow-up was conducted. Body composition, cardiorespiratory fitness and biomarkers of cardiometabolic health were measured in thirty-three participants with SCI (> 1 year post injury). Physical activity dimensions were objectively assessed over 7-days.

Results: Activity energy expenditure (r =.43), physical activity level (r =.39), and moderate-to-vigorous physical activity (MVPA) (r =.48) were significantly (P < 0.001) associated with absolute (L/min) peak oxygen uptake (?O₂ peak). ?O₂ peak was significantly higher in persons performing ≥150 MVPA minutes/week compared to <40 minutes/week (P?=?0.003). Individual physical activity dimensions were not significantly associated with biomarkers of cardiometabolic health. However, body composition characteristics (BMI, waist and hip circumference) showed significant (P < 0.04), moderate (r >.30) associations with parameters of metabolic regulation, lipid profiles and inflammatory biomarkers. Relative ?O₂ peak (ml/kg/min) was moderately associated with only insulin sensitivity (r?=?0.37, P?=?0.03).

Conclusions: Physical activity dimensions are associated with cardiorespiratory fitness; however, stronger and more consistent associations suggest that poor cardiometabolic health is associated with higher body fat content. Given these findings, the regulation of energy balance should be an important consideration for researchers and clinicians looking to improve cardiometabolic health in persons with SCI.     

An alternative approach to acid base abnormalities in critically ill patients

Contin Educ Anaesth Crit     

Prophylaxis againstMycobacterium avium-intracellulare complex infections in human immunodeficiency virus-infected patients

Summary Infection due to theMycobacterium avium complex (MAC) accounts for the most frequent AIDS-related opportunistic infections, but MAC infection is usually not the first AIDS-defining event that a patient infected with HIV experiences. The incidence increases linearly over time, at a rate of 20 to 25% per year, after a patient's first AIDS-defining event, and the incidence increases exponentially as the CD4+ cell count approaches zero. There is evidence that MAC may eventually infect most if not all HIV-infected patients who do not die from another HIV-related event. Since MAC infection contributes substantially to the morbidity and mortality of AIDS patients, prophylaxis appears to be mandatory. Rifabutin was the first drug which was shown to be effective in preventing MAC infection, and, recently, prophylaxis with clarithromycin was also found to prevent the disease. The optimal approach to prophylaxis still needs to be defined. Since a large majority of MAC infections occur in patients with CD4+ cell counts below 50/µl, recommendations regarding the prophylaxis of patients with a history of an AIDS-defining opportunistic event and a CD4+ cell count between 50 and 200/µl can be individualized, depending for example on how well the patient seems to be responding to antiretroviral treatment. Prophylaxis against MAC should be provided for any HIV-infected patient with a CD4+ cell count less than 50/µl.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

Considerations in dosage selection for third generation cephalosporins.

Pharmacokinetic parameters of third generation cephalosporins vary widely, requiring different dosage regimens and adjustment methods for each agent. Although their antibacterial spectrum favours their usage in infections caused by aerobic Gram-negative organisms, due to their limited post-antibiotic effect against these organisms, dosage regimens should ensure that free drug concentrations at the site of infection remain above the minimum inhibitory concentration for as much of the dosage interval as possible in patients with normal host defence mechanisms and for the entire dosage interval in immunocompromised patients. Altered protein binding encountered in various disease states can affect both microbiological and pharmacokinetic properties especially for drugs with high protein binding. Since the concentrations at the site of action are often different from those in serum, a higher or lower range of dosages needs to be selected depending on the target site. Decreased renal function affects the elimination of most third generation cephalosporins, whereas the presence of hepatic disease does not generally necessitate dosage adjustment. Because of the complex age-related physiological changes in paediatric and elderly patients, dosage should be adjusted on the basis of the reported pharmacokinetic data in these populations. The usual recommended dose may or may not be optimal in a given condition depending on the complex interactions between pharmacokinetic, microbiological and other host factors.     

Oxygen consumption following trauma: a reappraisal in severely injured patients requiring mechanical ventilation

Oxygen consumption (VO2) immediately following major injury in man has been said to be reduced. The evidence for this is poor. We have therefore measured VO2 soon after major injury in 16 patients. VO2 was reduced in only two patients, within the normal range in four and increased in ten. VO2 was maintained by increased oxygen extraction in six patients leading to low levels of mixed venous oxygen saturation. There is no evidence for an 'ebb phase' response in man.