The use of lingual venous blood to determine the acid-base and blood-gas status of dogs under anesthesia.

OBJECTIVE: To assess the suitability of lingual venous blood (LBG) as an alternative to arterial blood (ABG) samples in determining acid-base balance and blood-gas status in dogs anesthetized for elective procedures and with medetomidine and isoflurane administration under experimental conditions. STUDY DESIGN: Prospective, randomized clinical and experimental study. ANIMALS: Clinical population of 18 ASA I/II dogs for elective surgery and five healthy Beagles (3 females and 2 males) for the experimental study. METHODS: Blood sampling was simultaneously performed at dorsal pedal arterial and lingual venous sites, generating paired data. Two paired samples were collected from each dog in the clinical part and four from each dog in the experimental part (two during isoflurane anesthesia and two during isoflurane plus medetomidine). A modified Bland and Altman method was used to examine data from the clinical part and the experimental data were subjected to a paired sign's test following transformation where appropriate. RESULTS: The pH of LBG overestimated ABG, with limits of agreement of (-0.01, 0.02). The partial pressure of carbon dioxide (PCO(2)) of LBG overestimated ABG by 0.6 mmHg [0.1 kPa], with limits of agreement of (-3.5, 4.6) mmHg [-0.5, 0.6 kPa]. The partial pressure of oxygen (PO(2)) of LBG underestimated ABG by 86.3 mmHg [-11.5 kPa], with limits of agreement of (-199.8, 27.3) mmHg [-26.6, 3.6 kPa]. During medetomidine administration values for PO(2) (p = 0.03) and lactate (p = 0.03) were lower for LBG when compared with ABG. The LBG value of PO(2) was lower (p = 0.03) during medetomidine and isoflurane administration versus isoflurane alone. CONCLUSIONS AND CLINICAL RELEVANCE: The pH and PCO(2) of LBG samples provide clinically acceptable substitutes of ABG samples in the dog population studied. The wider limits of agreement for PO(2) render it less reliable as a substitute for ABG. The difference in PO(2) identified between LBG and ABG during medetomidine administration may not preclude the use of LBG as substitutes for ABG samples.

Skeletal muscle endurance and muscle metabolism in patients with chronic heart failure.

BACKGROUND: Alterations in skeletal muscle function are known to contribute to exercise intolerance in patients with chronic heart failure (CHF). OBJECTIVES: To evaluate whether muscle isometric endurance can be objectively measured and whether it is related to skeletal muscle metabolism in CHF. METHODS: Isometric endurance of the vastus lateralis, measured as time to fatigue (T(F)), was evaluated in 25 patients with CHF (55+/-8 years of age [mean +/- SD]) and 18 healthy subjects (HS) (62+/-6 years of age [mean +/- SD]). Median frequency of surface electromyography was obtained from spectral analysis using a fast Fourier transformation. Citrate synthase (CS), 3-hydroxyacyl-CoA dehydrogenase (HADH), hexokinase (HK) and phosphofructokinase (PFK) activities were determined from the right vastus lateralis muscle. RESULTS: T(F) was lower in CHF patients than in HS (49+/-4 s and 80+/-7 s, respectively; P<0.01). Muscle fatigue was present at the end of the endurance test in both groups (median frequency breakpoint at mid-exercise for both groups [P<0.05]). CS (P<0.01) and HK (P<0.01) activities were lower in CHF patients than in HS, but PFK activity was higher (P<0.05). T(F) correlated significantly with CS (r=0.50), HADH (r=0.42), PFK (r=-0.47) and HK (r=0.41) activities and the PFK/CS ratio (r=-0.39) when both groups were considered, and with HADH (r=0.47) and PFK (r=-0.57) activities for the CHF group alone (all P<0.05). CONCLUSIONS: These results suggest that isometric endurance of the vastus lateralis muscle is reduced in patients with CHF and that it is related to a reduced muscle oxidative capacity.

Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.

Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.