Indirect calorimetry during treadmill walking--a study of two methods.

Walking is a complex process and the physiotherapist must focus on physical signs as well as functional and practical tests to evaluate treatment. Measurement of energy expenditure during level walking is a useful objective parameter for assessing walking as being a valuable supplement to evaluate the outcome of physiotherapy. This study had two purposes. The first purpose was to investigate whether sampling and measurement of oxygen consumption were reproducible when using two different devices during walking on a treadmill. A second purpose was to find out whether the measurements were sensitive enough to reveal differences in energy expenditure and respiratory quotient (RO) during different walking speeds. Ten healthy students (mean age 22 years; range 20-25 years) volunteered in the test-retest of a slightly adjusted Deltatrac metabolic monitor. Thirteen volunteers (mean age 45 years; range 31-57 years) participated in the test-retest of Sensormedics 2900. In the first test, the subjects walked for 10 min in order to get a steady state both at an individual comfortable speed and at a preset speed. The retest was done with the same design and within 2 weeks. Nobody experienced any discomfort during the tests. The repeatability of measuring energy expenditure and RQ was acceptable for both methods and the methods were sensitive in revealing differences in energy expenditure during different walking speeds. The RQ were, however, too low when using the Deltatrac monitor, probably as a result of low air flow. We therefore conclude that only the method using Sensormedics 2900 may be used for the evaluation of energy expenditure during walking on a treadmill.

Hb Trollhättan [beta 20(B2)Val-->Glu]--a new haemoglobin variant with increased oxygen affinity causing erythrocytosis.

Erythrocytosis is sometimes caused by the presence of haemoglobin (Hb) variants with increased oxygen affinity. Here we describe a beta-globin variant found by isoelectric focusing (IEF) of Hb from a 23-year-old Swedish male with moderate erythrocytosis. Amplification of DNA corresponding to the beta-globin gene and subsequent nucleotide sequencing revealed heterozygosity for a GTG-->GAG mutation at codon 20, thus suggesting a Val-->Glu substitution, which was confirmed at the protein level. This mutation occurs at the same position as Hb Olympia [beta 20(B2)Val-->Met], another variant associated with erythrocytosis due to increased oxygen affinity. The novel variant, Hb Trollhättan [beta 20(B2)Val-->Glu], which was also associated with increased oxygen affinity, was shown to be present in three generations of the patient's family.

Measurement of oxygen and carbon dioxide partial pressures in synovial fluid after tonometry.

A commercially available gas analyser was used to measure tension of oxygen (PO2) and carbon dioxide (PCO2) in synovial fluid samples after tonometry. Measured values of PCO2 were close to the expected (median difference 0.2 kPa, range -0.4 to 0.4) within the analysed concentration range of 4-10 kPa. No consistent difference between measured and expected values of PO2 were found for oxygen in the range 3-11 kPa (median difference 0.1 kPa, range -0.3 to 1.2). For oxygen tensions below 3 kPa, however, the measured values invariably overestimated the actual PO2, the errors ranging from 0.3 to 1.9 kPa, median 1.1. The importance of proper handling of samples was investigated and storage for 1 h at 0 degrees C in plastic syringes resulted in elevation of the PO2 levels measured (range of elevation 0.2 to 3.6 kPa, median 1.15), whilst no significant differences were found when stored in glass syringes. Within the limits stated, commercially available gas analysers may thus be used to investigate these parameters related to local tissue metabolism in effusive joint conditions.