Evaluation of isotonic sodium bicarbonate solution for alkalizing effects in conscious calves.
(73/455)
After intravenous (i.v.) infusion of various volumes of 1.35%-isotonic sodium bicarbonate solution (ISB), acid-base equilibrium, blood pressure, plasma volume and biochemical parameters in healthy Holstein calves were studied. Four calves each were randomly assigned to the low-dose (LD; i.v. infusion of 5 ml/kg ISB), middle-dose (MD; i.v. infusion of 10 ml/kg ISB) and the high-dose groups (HD; i.v. infusion of 15 ml/kg ISB). Administration volumes of ISB in the LD, MD and HD groups were decided based on the first half volumes of 5, 10 and 15 mEq of base requirement by the acceptable equation. Systemic, pulmonary artery and central venous pressures, cardiac output and plasma osmotic pressure were not changed by ISB infusion and remained constant throughout the experiment for all groups. There was good correlation (r(2) = 0.950) between relative changes in base excess and infused volume of bicarbonate (y=2.491x). The coefficient of distribution for bicarbonate ions was calculated to be 0.401 (=1/2.491). Therefore, it is suggested that a value of 0.4 would be most appropriate when calculating the base requirements in calves. Therefore, the first half volumes of ISB correcting base deficits of 5, 10 and 15 mEq in calves were estimated to be 6, 12 and 18 ml/kg, respectively. On the basis of the findings in this study, ISB may be used to correct metabolic acidosis without altering the plasma osmotic pressure, hemodynamic status and respiratory function in the calves. (+info)
Goal-directed intraoperative fluid administration reduces length of hospital stay after major surgery.
(74/455)
BACKGROUND: Intraoperative hypovolemia is common and is a potential cause of organ dysfunction, increased postoperative morbidity, length of hospital stay, and death. The objective of this prospective, randomized study was to assess the effect of goal-directed intraoperative fluid administration on length of postoperative hospital stay. METHODS: One hundred patients who were to undergo major elective surgery with an anticipated blood loss greater than 500 ml were randomly assigned to a control group (n = 50) that received standard intraoperative care or to a protocol group (n = 50) that, in addition, received intraoperative plasma volume expansion guided by the esophageal Doppler monitor to maintain maximal stroke volume. Length of postoperative hospital stay and postoperative surgical morbidity were assessed. RESULTS: Groups were similar with respect to demographics, surgical procedures, and baseline hemodynamic variables. The protocol group had a significantly higher stroke volume and cardiac output at the end of surgery compared with the control group. Patients in the protocol group had a shorter duration of hospital stay compared with the control group: 5 +/- 3 versus 7 +/- 3 days (mean +/- SD), with a median of 6 versus 7 days, respectively ( = 0.03). These patients also tolerated oral intake of solid food earlier than the control group: 3 +/- 0.5 versus 4.7 +/- 0.5 days (mean +/- SD), with a median of 3 versus 5 days, respectively ( = 0.01). CONCLUSIONS: Goal-directed intraoperative fluid administration results in earlier return to bowel function, lower incidence of postoperative nausea and vomiting, and decrease in length of postoperative hospital stay. (+info)
Haemoglobin Rahere (beta Lys-Thr): A new high affinity haemoglobin associated with decreased 2, 3-diphosphoglycerate binding and relative polycythaemia.
(75/455)
A new haemoglobin with increased oxygen affinity, beta82 (EF6) lysine leads to threonine (Hb Rahere), was found during the investigation of a patient who was found to have a raised haemoglobin concentration after a routine blood count. The substitution affects one of the 2, 3-diphosphoglycerate binding sites, resulting in an increased affinity for oxygen, but both the haem-haem interaction and the alkaline Bohr effect are normal in the haemolysate. This variant had the same mobility as haemoglobin A on electrophoresis at alkaline pH but was detected by measuring the whole blood oxygen affinity; it could be separated from haemoglobin A, however, by electrophoresis in agar at acid pH. The raised haemoglobin concentration was mainly due to a reduction in plasma volume (a relative polycythaemia) and was associated with a persistently raised white blood count. This case emphasises the need to measure the oxygen affinity of haemoglobin in all patients with absolute or relative polycythaemia when some obvious cause is not evident. (+info)
Hemodilution is common in patients with advanced heart failure.
(76/455)
BACKGROUND: Anemia frequently occurs in chronic heart failure (CHF) patients and is associated with a poor prognosis. A low hematocrit may result from an increased plasma volume (hemodilution) or from reduced red blood cell volume (true anemia). The prevalence and clinical outcome of CHF patients with hemodilution is unknown. METHODS AND RESULTS: The prevalence of anemia and its effect on outcome was examined in 196 patients with CHF. The prevalence of hemodilution was assessed in a subset of 37 ambulatory anemic patients with I131-tagged albumin to measure red blood cell and plasma volume. Clinical outcome was monitored. Sixty-one percent of the CHF patients were anemic. The prevalence of anemia increased from 33% in patients with New York Heart Association class II heart failure to 68% in class IV CHF patients. Survival was reduced in anemic patients compared with patients with a normal hematocrit (P<0.05). In the subset of 37 anemic patients, 17 patients (46%) had hemodilution and 20 patients (54%) had a true anemia. Nine patients with hemodilution died or underwent urgent transplant compared with 4 patients in the true anemia group (P<0.04). CONCLUSION: Hemodilution is common in CHF patients. Anemia is associated with a poor prognosis in CHF. Patients with hemodilution tend to do worse than patients with true anemia, which suggests that volume overload may be an important mechanism contributing to the poor outcome in anemic CHF patients. (+info)
Effect of erythropoietin on exercise capacity in patients with moderate to severe chronic heart failure.
(77/455)
BACKGROUND: Patients with chronic heart failure (CHF) are frequently anemic. An increase in hemoglobin could enhance exercise performance by increasing oxygen delivery. We investigated the effect of erythropoietin (EPO) on exercise performance in anemic patients with CHF. METHODS AND RESULTS: Twenty-six anemic patients aged 57+/-11 years were randomized to receive EPO (15 000 to 30 000 IU per week) or placebo for 3 months. Parameters measured at baseline and end therapy included blood parameters (hemoglobin, hematocrit, plasma volume), exercise parameters (peak oxygen consumption [VO2], exercise duration, 6-minute walk), muscle aerobic metabolism (half-time of VO2 and near infrared recovery), and forearm vasodilatory function. EPO was well tolerated by all patients. Twelve patients in the EPO group felt improvement versus 1 in the placebo group (P<0.05). There were significant increases in hemoglobin (11.0+/-0.5 to 14.3+/-1.0 g/dL, P<0.05), peak VO2 (11.0+/-1.8 to 12.7+/-2.8 mL. min(-1) x kg(-1), P<0.05) and exercise duration (590+/-107 to 657+/-119 s, P<0.004) in the EPO group but no significant changes in the control group. Resting and hyperemic forearm vascular resistance and indices of the rate of muscle oxidative capacity were unchanged in both groups. CONCLUSION: EPO significantly enhances exercise capacity in patients with CHF. One mechanism of improvement in VO2 is increased oxygen delivery from increased hemoglobin concentration. (+info)
Mice lacking endothelial ACE: normal blood pressure with elevated angiotensin II.
(78/455)
Recently, the concept of local renin-angiotensin systems (RAS) capable of generating angiotensin II apart from the circulation has received considerable attention. To investigate this, we generated ACE 1/3 mice in which one allele of ACE is null and the second allele was engineered to express ACE on the surface of hepatocytes. ACE 1/3 mice express no endothelial ACE and lack ACE within the lungs. Their kidneys contain <7.8% the enzyme levels present in control mice. Plasma conversion of angiotensin I to angiotensin II was 43.3% normal. The baseline blood pressure and renal function of the ACE 1/3 mice were normal, probably as a function of a marked increase of both plasma angiotensin I and angiotensin II. When exposed to 2 weeks of a salt-free diet (a stress diet stimulating the RAS), blood pressure in ACE 1/3 mice decreased to 92.3+/-2.0 mm Hg, a level significantly lower than that of wild-type control mice. The ACE 1/3 mice demonstrate the plasticity of the RAS and show that significant compensation is required to maintain normal, basal blood pressure in a mouse with an impaired local vascular and renal RAS. (+info)
Mechanism of dilutional anemia in massive splenomegaly.
(79/455)
Twenty patients with anemia and massive splenomegaly were studied in order to elucidate the mechanism by which splenomegaly results in plasma volume expansion. In 18 patients, increased plasma volume accounted for most of the anemia. Fourteen patients had an exaggerated renin response to standing, mean 1967 +/- 613 (SE) ng angiotensin ll/100 ml plasma (p less than 0.05). The mean resting forearm blood flow was increased 3.47 +/- 0.32 (SE) ml/100 ml forearm tissue (p less than 0.001). The venous capacitance was normal, as contrasted to a marked decrease in venous capacitance in patients with anemia of comparable degree without splenomegaly. Cardiac indices were increased in 10 of 11 patients (range 4.1-8.1 liters/min/sq m). In nine of ten patients oxygen consumption was increased (range 147-231 ml/min/sq m). Splenectomy was performed on 14 patients. Splenic blood flow was elevated in four of four patients (range 750-2000 ml/min). Splenic A-V oxygen difference was exaggerated in seven of seven patients and in three of three patients splenic indocyanine-green dye dilution curve failed to show an early peak suggestive of A-V shunting in the spleen. Free portal pressure was elevated in 12 of 12 patients and decreased immediately after splenectomy. The intravascular albumin mass decreased in ten patients, was unchanged in three at 2-4 mo after splenectomy, and was accompanied by a rise in the plasma albumin concentration in nine. These data suggest that a flow-induced portal hypertension with expansion of the portal vascular space is an important early hemodynamic change. This finding, together with a decreased peripheral resistance, probably results in a decrease in effective intravascular volume, resulting in stimulation of the renin-angiotensin-aldosterone system and other renal hemodynamic changes necessary for salt and water retention. Splenectomy usually accomplishes a complete reversal of these abnormalities and correction of the anemia. (+info)
Short-term aerobic training and circulatory function in women: age and hormone-replacement therapy.
(80/455)
The physiological basis of training responses in women, and particularly older women, is not well understood. Short-term aerobic training (STAT) was used to probe the effects of age and hormone-replacement therapy (HRT) on women's ability to rapidly change peak uptake ( VO(2max)), plasma volume and cardiac function. A total of 39 females participated in the STAT programme: 15 younger (Y; aged 19-29 years), 12 postmenopausal women undergoing HRT and 12 non-medicating postmenopausal (PM) women (aged 60-75 years). Training consisted of ten sessions of cycling over a 2-week period, which progressed in duration from 20 to 60 min and in intensity from 60-75% of maximum heart rate. Plasma volume (PV; as determined by Evan's Blue dye dilution), VO(2max) (cycle ergometry) and cardiac function (radionuclide ventriculography) were analysed using analysis of covariance or repeated measures ANOVA. All groups demonstrated similar increase in VO(2max) (Y, 13%; PM, 17%; HRT, 13%), but without a significant change in left-ventricular ejection fraction and diastolic function or volumes during supine exercise. PV expansion was observed among the Y group (7%; P <0.05) but not the PM group (2%; P >0.05) or women undergoing HRT (1%; P >0.05). Age and hormone-replacement status did not affect the magnitude of VO(2max) change. This study suggests that STAT improves VO(2max), independent of central adaptations. (+info)