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Biomedical subjects

J Gamble

Publications and source records attributed to J Gamble.

At least 55 records · Page 3Linked to original sources
PubMed1997

Changes in subcutaneous interstitial fluid pressure, tissue oxygenation, and skin red cell flux during venous congestion plethysmography in men.

OBJECTIVE: Venous congestion plethysmography enables noninvasive assessment of microvascular filtration capacity (Kf) in limbs. However, increases in fluid filtration might alter the balance of Starling forces: for example, progressive increases in interstitial fluid pressure (Pi) would reduce net fluid flux, thus underestimating Kf. Furthermore, elevation of cuff pressure to values close to diastolic blood pressure, as used in the protocol, may be itself impair tissue perfusion with unknown effects on the microvascular parameters investigated. METHODS: Pi was measured in healthy volunteers (n = 14) with a modified "Wick in needle" technique during small (8 mm Hg) cumulative increases in venous pressure (0-95 mm Hg). Changes in the hemoglobin (Hb) concentration, oxygenated hemoglobin (HbO2) concentration and oxidized cytochrome aa3 concentration were assessed in the calf using noninvasive near-infrared spectroscopy. Skin red blood cell flux close to the strain gauge was evaluated by laser Doppler fluxmetry. RESULTS: Pi at control was -0.89 +/- 0.8 mm Hg and during elevation of venous pressure remained constant until a cuff pressure of 30 mm Hg was reached. It rose thereafter to 1.57 +/- 1.3 mm Hg (mean +/- SD). Skin red cell flux was significantly reduced when cuff pressure exceeded 30 mm Hg and following cuff deflation, evidence of reactive hyperemia was obtained. Hb concentration increased significantly as a result of venous pressure elevation. No change in either HbO2 or cytochrome aa3 concentration was observed as long as cuff pressure remained under diastolic blood pressure. CONCLUSIONS: The small increase in Pi together with an absence of impaired tissue oxygenation during the venous congestion plethysmography protocol described by Gamble et al. supports the contention that this protocol enables accurate assessment of filtration capacity.

Adult↗
PubMed1997

Microvascular fluid filtration capacity (Kf) assessed with cumulative small venous pressure steps and with various degrees of tilt.

Tilt procedures are frequently used to test central and peripheral cardio-vascular reflexes. We have previously used venous congestion strain gauge plethysmography for measurement of fluid filtration capacity (Kf) in human legs and have shown that, providing small cumulative venous congestion pressure steps are applied, venous congestion pressure can be increased to arterial diastolic pressure without activating peripheral vasoconstrictor mechanisms. We have also studied the effect of passive tilting on Kf and have shown that the procedure does not influence the measured value Kf indicating that passive tilting does not after the total surface area available for fluid filtration, but rather the blood flow in the microvessels of the tissue under study. In the present protocol we compared the fluid filtration (Jv) resulting from small (7-10 mmHg) cumulative pressure steps with those obtained by altering hydrostatic load with progressive increases and decreases of head down tilt of -8 degrees -15 degrees and -30 degrees, followed by a similar pattern of 15 degrees, 30 degrees and 70 degrees of head up tilt. The values of Jv obtained in response to these procedures were compared with those deduced from the relationship between fluid filtration and venous congestion pressure (Pcuff) obtained during the small cumulative pressure step protocol. It was reasoned that reflex activation, by the tilt induced pressure load, would cause a reduction in local blood flow and enhanced microvascular fluid extraction. The resulting local increase in colloid osmotic pressure would give rise to lower values of Jv than those predicted on the basis of the Kf slope.

Adult↗
PubMed1995

Investigating the origin of cyclic changes in limb volume using mercury-in-silastic strain gauge plethysmography in man.

1. Vasomotion, a phenomen frequently observed in skeletal muscle microcirculation, has been observed under physiological conditions and found enhanced during critical reduction of tissue perfusion due to hypoxic hypoxia, haemorrhage and local hypotension. We used a computer assisted non-invasive plethysmographic method to investigate periodic changes of limb volume (volumotion), which we previously found in critically ill patients. The current study was designed to investigate the origin of volumotion. 2. Simultaneous recordings of limb circumference of both calves were obtained. In patients with peripheral vascular disease and patients with minor surgery the cross-correlation with spontaneous breathing was investigated. In patients who had undergone major abdominal or vascular surgery we analysed for cross-correlations between MSG plethysmography signals of both legs and changes in central venous, arterial and ventilation pressures. In this group the effects of positive-pressure ventilation and positive end-expiratory pressure (PEEP) were also studied. 3. No ventilation-related volumotion was observed during spontaneous breathing. During positive-pressure ventilation a ventilation-related peak was found in the Fourier transform in agreement with the ventilation frequency applied. The amplitude of ventilation-related volumotion decreased significantly after a pressure cuff applied to the thigh was inflated above central venous pressure. We observed a significant increase in the amplitude of ventilation-related volumotion when PEEP was applied. 4. Ventilation-related volumotion showed significant cross-correlation between both legs. Slow wave volumotion (0.5-7 cycles min-1) was frequently observed, but always appeared unilaterally. Whilst we looked for correlations between slow wave volumotion and changes in central venous pressure and arterial blood pressure, respectively, significant cross-correlation with the MSG plethysmography recordings was only observed at the frequency of the positive-pressure ventilation. 5. The fact that periodic changes of limb circumference matching the frequency of the positive-pressure ventilation were detectable with the MSG plethysmography system demonstrates that small volume changes (less than 0.02 ml (100 ml tissue)-1) can be assessed using this system. As slow wave volumotion was observed unilaterally and revealed no correlation either with breathing, ventilation or arterial and central venous pressure, we suggest that slow wave volumotion is a local event most likely reflecting arteriolar vasomotion.

Aged↗
PubMed1995

L-carnitine improvement of cardiac function is associated with a stimulation in glucose but not fatty acid metabolism in carnitine-deficient hearts.

OBJECTIVES: Increasing myocardial carnitine content can improve heart function in patients with carnitine deficiency. We were interested in determining the effects of L-carnitine on cardiac function and substrate metabolism in a rat model of carnitine deficiency. METHODS: Carnitine deficiency was induced in male Sprague-Dawley rats by supplementing the drinking water with 20 mM sodium pivalate. Control animals received an equimolar concentration of sodium bicarbonate. Following treatment, cardiac function and myocardial substrate utilization were determined in isolated working hearts perfused with glucose and relevant levels of fatty acids. To increase tissue levels of carnitine, hearts were perfused with 5 mM L-carnitine for a period of 60 min. RESULTS: Hearts from sodium pivalate-treated animals demonstrated a 60% reduction in total heart carnitine content, depressions in cardiac function and rates of palmitate oxidation, and elevated rates of glycolysis compared to control hearts. Treatment with L-carnitine increased total carnitine content and reversed the depression in cardiac function seen in carnitine-deficient hearts. However, this was not associated with any improvement in palmitate oxidation. Rates of glycolysis and glucose oxidation, on the other hand, were increased with L-carnitine. CONCLUSIONS: Our findings indicate that acute L-carnitine treatment is of benefit to cardiac function in this model of secondary carnitine deficiency by increasing overall glucose utilization rather than normalizing fatty acid metabolism.

Animals↗
PubMed1994

Glycolysis and glucose oxidation during reperfusion of ischemic hearts from diabetic rats.

Stimulation of glucose oxidation by dichloroacetate (DCA) treatment is beneficial during recovery of ischemic hearts from non-diabetic rats. We therefore determined whether DCA treatment of diabetic rat hearts (in which glucose use is extremely low), increases recovery of function of hearts reperfused following ischemia. Isolated working hearts from 6 week streptozotocin-diabetic rats were perfused with 11 mM [2-3H/U-14C]glucose, 1.2 mM palmitate, 20 microU/ml insulin, and subjected to 30 min of no flow ischemia followed by 60 min reperfusion. Heart function (expressed as the product of heart rate and peak systolic pressure), prior to ischemia, was depressed in diabetic hearts compared to controls (HR x PSP x 10(-3) was 18.2 +/- 1 and 24.3 +/- 1 beats/mm Hg/min in diabetic and control hearts respectively) but recovered to pre-ischemic levels following ischemia, whereas recovery of control hearts was significantly decreased (17.8 +/- 1 and 11.9 +/- 3 beats/mm Hg/min in diabetic and control hearts respectively). This enhanced recovery of diabetic rat hearts occurred even though glucose oxidation during reperfusion was significantly reduced as compared to controls (39 +/- 6 and 208 +/- 42 nmol/min/g dry wt, in diabetic and control hearts respectively). Glycolytic rates (3H2O production) during reperfusion were similar in diabetic and control hearts (1623 +/- 359 and 2071 +/- 288 nmol/min/g dry wt, respectively). If DCA (1 mM) was added at reperfusion, hearts from control animals exhibited a significant improvement in function (HR x PSP x 10(-3) recovered to 20 +/- 4 beats/mm Hg/min) that was accompanied by a 4-fold increase in glucose oxidation (from 208 +/- 42 to 753 +/- 111 nmol/min/g dry wt). DCA was without effect on functional recovery of diabetic rat hearts during reperfusion but did significantly increase glucose oxidation from 39 +/- 6 to 179 +/- 44 nmol/min/g dry wt). These data suggest that, unlike control hearts, low glucose oxidation rates are not an important factor in reperfusion recovery of previously ischemic diabetic rat hearts.

Animals↗
PubMed1994

A study of factors governing fluid filtration in the diabetic foot.

The effect of lowering the foot on the factors governing fluid filtration in the foot were studied in 12 male insulin-dependent diabetic subjects and 10 controls. Toe skin blood flow, measured by laser Doppler flowmetry, was significantly higher during dependency in the diabetic group. In the control subjects, the colloid osmotic pressure of venous blood sampled from the foot rose to 47.7 mmHg (range 45.1-53.8) after 50 min of foot dependency. In the diabetic group, colloid osmotic pressure failed to rise to the same extent (median 36.7 mmHg; range 28.6-43.0; P < 0.001). Capillary pressure, measured directly by the Landis microinjection technique, was significantly higher in the diabetic group (85.3 +/- 1.7 (n = 6) vs. 92.2 +/- 4.6 cm H2O (n = 6); P < 0.007), as was foot swelling rate determined by mercury strain gauge plethysmography (0.069 +/- 0.022 vs. 0.099 +/- 0.025 ml min-1 100 ml-1; P < 0.02). These results suggest an impairment of the oedema-preventing mechanisms in diabetic subjects which may contribute to the risks of ulceration in the diabetic foot.

Adult↗
PubMed1994

The 1993 Merck Frosst Award. Acetyl-CoA carboxylase: an important regulator of fatty acid oxidation in the heart.

It has long been known that most of the energy production in the heart is derived from the oxidation of fatty acids. The other important sources of energy are the oxidation of carbohydrates and, to a lesser extent, ATP production from glycolysis. The contribution of these pathways to overall ATP production can vary dramatically, depending to a large extent on the carbon substrate profile delivered to the heart, as well as the presence or absence of underlying pathology within the myocardium. Despite extensive research devoted to the study of the individual pathways of energy substrate metabolism, relatively few studies have examined the integrated regulation between carbohydrate and fatty acid oxidation in the heart. While the mechanisms by which fatty acids inhibit carbohydrate oxidation (i.e., the Randle cycle) have been characterized, much less is known about how carbohydrates regulate fatty acid oxidation in the heart. It is clear that an increase in intramitochondrial acetyl-CoA derived from carbohydrate oxidation (via the pyruvate dehydrogenase complex) can downregulate beta-oxidation of fatty acids, but it is not clear how fatty acid acyl group entry into the mitochondria is downregulated when carbohydrate oxidation increases. Recent interest in our laboratory has focused on the involvement of acetyl-CoA carboxylase (ACC) in this process. While it has been known for some time that malonyl-CoA does exist in heart tissue, and that it is a potent inhibitor of carnitine palmitoyltransferase 1 (CPT 1), it has only recently been demonstrated that an isoenzyme of ACC exists in the heart that is a potential source of malonyl-CoA.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetyl Coenzyme A↗
PubMed1993

Acetyl-CoA carboxylase regulation of fatty acid oxidation in the heart.

The role of acetyl-coenzyme A carboxylase (ACC) in regulating fatty acid oxidation was investigated in isolated fatty acid perfused working rat hearts. Overall fatty acid oxidation rates were determined by addition of 1.2 mM [3H]palmitate to the perfusate of hearts in which the endogenous triglyceride pool was prelabeled with [14C]palmitate. Rates of both exogenous and endogenous fatty acid oxidation were measured by simultaneous measurement of 3H2O and 14CO2 production, respectively. A second series of hearts were perfused under similar conditions except that [U-14C]glucose was present in the perfusate for measurement of glucose oxidation rates. Addition of dichloroacetate (DCA, 1 mM) to the perfusate resulted in a dramatic stimulation of glucose oxidation (a 411% increase), with a parallel decrease in fatty acid oxidation (from 305 +/- 51 to 206 +/- 40 nmol/g dry weight.min.unit work). DCA treatment increased the contribution of glucose oxidation to ATP production from 7.1 to 30.6%, while decreasing the contribution of overall fatty acid oxidation from 92.9 to 69.4%. Tissue levels of malonyl-CoA in hearts treated with DCA were higher compared to controls (14.0 +/- 0.6 and 10.0 +/- 0.7 nmol/g dry weight, respectively) and were negatively correlated (r = -0.85) with overall fatty acid oxidation rates. Acetyl-CoA levels were also significantly higher in DCA-treated hearts, and a positive correlation (r = 0.88) was seen between myocardial acetyl-CoA and malonyl-CoA levels. This suggests that DCA treatment increased the supply of acetyl-CoA for ACC. Western blots revealed the presence of both the 280-kDa (ACC-280) and the 265-kDa (ACC-265) isoforms of ACC in cardiac tissue, with a predominance of ACC-280. The activity of ACC extracted from hearts was similar in both groups when assayed under optimal conditions of acetyl-CoA and citrate. However, using affinity purified ACC, it was demonstrated that heart ACC (predominantly ACC-280) had a higher Km for acetyl-CoA than ACC isolated from white adipose tissue (predominantly ACC-265). We conclude that ACC is an important regulator of fatty acid oxidation in the heart and that acetyl-CoA supply is a key determinant of heart ACC-280 activity. As acetyl-CoA levels increase, ACC-280 is activated resulting in an increase in malonyl-CoA inhibition of fatty acid oxidation.

Acetyl-CoA Carboxylase↗
PubMed1993

Increased microvascular fluid permeability in young type 1 (insulin-dependent) diabetic patients.

Microvascular fluid permeability was assessed by determination of the capillary filtration coefficient in the forearm of ten young Type 1 (insulin-dependent) diabetic patients with a short duration of diabetes, satisfactory glycaemic control and minimal evidence of microangiopathy, and ten age- and sex-matched control subjects. A strain gauge plethysmographic method with a computer based logging and analysis system was used. This enabled differentiation between the volume filling and fluid filtration components of the response to venous pressure elevation. The median capillary filtration coefficient was found to be significantly higher in the young diabetic patients in comparison with control subjects (9.2 x 10(-3) ml.min-1.100 g tissue-1.mmHg-1 vs 3.8 x 10(-3) ml.min-1.100 g tissue-1.mmHg-1, p < 0.001). There were no significant correlations between capillary filtration coefficient and either plasma glucose concentration, haemoglobin A1c or duration of diabetes. As there is no evidence from other studies to support an increase in capillary surface area in the forearms of young Type 1 diabetic patients, these results may reflect a primary change in microvascular fluid permeability.

Adolescent↗
PubMed1993

A reassessment of mercury in silastic strain gauge plethysmography for microvascular permeability assessment in man.

1. We have used non-invasive mercury in a silastic strain gauge system to assess the effect of pressure step size, on the time course of the rapid volume response (RVR) to occlusion pressure. We also obtained values for hydraulic conductance (Kf), isovolumetric venous pressure (Pvi) and venous pressure (Pv) in thirty-five studies on the legs of twenty-three supine control subjects. 2. The initial rapid volume response to small (9.53 +/- 0.45 mmHg, mean +/- S.E.M.) stepped increases in venous pressure, the rapid volume response, could be described by a single exponential of time constant 15.54 +/- 1.14 s. 3. Increasing the size of the pressure step, to 49.8 +/- 1.1 mmHg, gave a larger value for the RVR time constant (mean 77.3 +/- 11.6 s). 4. We propose that the pressure-dependent difference in the duration of the rapid volume response, in these two situations, might be due to a vascular smooth muscle-based mechanism, e.g. the veni-arteriolar reflex. 5. The mean (+/- S.E.M.) values for Kf, Pvi and Pv were 4.27 +/- 0.18 (units, ml min-1 (100 g)-1 mmHg-1 x 10(-3), 21.50 +/- 0.81 (units, mmHg) and 9.11 +/- 0.94 (units, mmHg), respectively. 6. During simultaneous assessment of these parameters in arms and legs, it was found that they did not differ significantly from one another. 7. We propose that the mercury strain gauge system offers a useful, non-invasive means of studying the mechanisms governing fluid filtration in human limbs.

Arm↗
PubMed1993

[Microvascular monitoring using mercury in silastic strain gauge plethysmography (MSG)].

Mercury in silastic strain gauge plethysmography (MSG) is a noninvasive method for assessing microvascular parameters in peripheral limbs. MSG allows measurement of capillary filtration coefficient (Kf), isovolumetric venous pressure (Pvi), venous pressure (Pv) and arterial inflow (Qa) into the limb, respectively. We used MSG in combination with invasive monitoring techniques (pulmonary artery flotation catheters and arterial catheters) to study 36 critically ill patients in either hemorrhagic or septic shock. We observed marked increases in Pvi in both patient groups which correlated with outcome. On admission, both groups showed elevated values for Pvi, survivors 37.7 +/- 2.6, nonsurvivors 33.7 +/- 3.5 mm Hg (mean +/- SEM) when compared with a control group of young healthy students (22.1 +/- 0.82 mm Hg). Survivors showed a decrease in Pvi to 27.3 +/- 1.7 mm Hg, whereas in nonsurvivors Pvi increased to 39.5 +/- 3.0 at the last measurement taken. The changes in Pvi depended on the resuscitation regime used. On admission, patients requiring only fluid replacement (F) had a lower Pvi (31.3 +/- 2.9 mm Hg) than patients needing inotropic support with dobutamine (D, Pvi = 38.2 +/- 2.4 mm Hg) to fulfill our therapeutic goals (DO2 > 550 ml.min-1 x m-2, VO2 > 150 ml.min-1 x m-2 and mixed venous lactate < 1.5 mmol/l). After treatment Pvi did not change significantly in the F group (31.3 +/- 1.8), the D group however showed a significant decrease in Pvi to 25.4 +/- 2.42, which did not differ from the normal value. We regard Pvi as an indicator of insufficient microvascular flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Formate metabolism in micropigs.

The toxicity of methanol is directly related to the accumulation of formate which, in turn, is related to the adequacy of the folate-dependent metabolism of formate to carbon dioxide. Thus, humans who possess low hepatic folates and low 10-CHO H4folate dehydrogenase activity metabolize formate poorly and are sensitive to methanol. Conversely, most laboratory species do not exhibit methanol toxicity because they metabolize formate at high rates. Studies reported here show that the Yucatan micropig has the lowest hepatic folates of any animal species studied. Formate oxidation rates in micropigs were 23% of rates reported for rats. The half-life of formate disappearances from the blood was 74 min, a value twice that reported for rats. In addition, 10-CHO H4folate dehydrogenase activity and amount in micropig liver is markedly reduced. Micropigs may prove useful in studies of methanol poisoning due to their low capacity for formate oxidation and their reasonable size and ease in handling.

Animals↗
PubMed1992

Myocardial stretch alters twitch characteristics and Ca2+ loading of sarcoplasmic reticulum in rat ventricular muscle.

OBJECTIVE: The aim was to determine the influence of diastolic muscle length on force development and timing parameters of cardiac muscle twitch contraction and to determine whether a length dependency exists for the calcium loading capacity of the sarcoplasmic reticulum. METHODS: Right ventricular papillary muscles and trabeculae were isolated from hearts of female Wistar rats weighing 220-280 g. Papillary muscles were stretched to diastolic lengths of 90, 95, and 100% Lmax and paced at 1.0 Hz. Individual twitch profiles were characterised by their peak force and the maximum rate (dF/dt) of the positive and negative force changes. Intrinsic timing was identified through waveform analysis that divided the twitch profile into time domains for the ascending limb (T0-T1; T1-T2) and the descending limb (T2-T3; T3-T4). Each domain was compared at three muscle lengths. The sarcoplasmic reticular calcium content at short (1.88 microns) and long (2.11 microns) sarcomere lengths was characterised by rapid cooling contractures after 1 s and 60 s of diastolic rest. RESULTS: Peak developed force and the maximum rate of positive and negative force development decreased as diastolic muscle length was reduced from Lmax to 90% Lmax. The intrinsic timing for the segment that reflects the relaxation phase of the twitch (T1-T4) was shortened as muscle length was reduced. The time domain that reflects the combined effects of calcium release and the early phase of contraction (T0-T1) was insensitive to diastolic muscle length. The fractional release of sarcoplasmic reticular calcium at different muscle lengths was approximately 32-35% of the total sarcoplasmic reticulum calcium pool. CONCLUSIONS: The data on the intrinsic timing of the twitch characteristics coupled with rapid cooling contracture analysis suggests a fractional calcium release that is approximately 32-35% of the total sarcoplasmic reticular capacity at either long or short muscle lengths. However, the loading capacity of the sarcoplasmic reticulum is greater when the muscle operates at a shorter diastolic length. This can be interpreted as meaning that diastolic muscle length differentially influences sarcoplasmic reticular calcium storage and release processes.

Animals↗
PubMed1992

Mercury in silastic strain gauge plethysmography for the clinical assessment of the microcirculation.

We have used the mercury in silastic strain gauge plethysmography (MSG) system, which is wholly non-invasive, to obtain values (mean +/- s.e.m.) for the following parameters in the legs of supine control subjects: venous pressure (Pv) 9.89 +/- 0.88 mmHg, vascular compliance (Comp) 3.50 +/- 0.29 ml 100 g-1 mmHg-1 x 10(-2), microvascular hydraulic conductivity (Kf) 4.10 +/- 0.16 ml min-1 100 g-1 mmHg-1 x 10(-3) and isovolumetric venous pressure (Pvi) 22.12 +/- 0.82 mmHg. On passive foot-down tilting of control subjects through about 45 degrees, both Pv and Pvi rose to 28.00 +/- 2.33 and 36.58 +/- 2.29 mmHg respectively. The increases in both parameters were highly significant, P < 0.0001. We found that the time course of the vascular compliance component was short if small pressure steps were used. The value increased markedly if large steps were used. We also observed that none of the microvascular parameters studied in the arms differed from those in the legs of the same subjects. We observed that the mean value Kf in the arms of 12 young, non-neuropathic diabetics (9.08 +/- 6.12 x 10(-3)) was significantly greater than that of age and sex-matched controls (P < 0.001). Studies on 14 venous ulceration patients indicated that the values for Kf and Pv were unchanged, whilst those of vascular compliance (5.60 +/- 0.58 x 10(-2) ml 100 g-1 mmHg-1) and Pvi (37.30 +/- 2.25 mmHg) were significantly greater than those found in age-matched controls (P < 0.002 and 0.001, respectively). We feel that Pvi is a useful index of microvascular perfusion. We attribute the pressure-dependent difference, in the time course of the vascular compliance response, to the veni-arteriolar reflex. We feel that the pressure dependency of this response might form the basis for the assessment of peripheral autonomic neuropathy. We believe that the MSG system offers a means of monitoring the development of pathologies resulting from microvascular under-perfusion and, of course, the improvement in response to therapeutic interventions.

Adult↗
PubMed1991

The assessment of the microcirculatory effects of dobutamine using mercury in silastic strain gauge plethysmography in man.

Adverse changes in the microcirculation are currently considered as the most likely common pathway of organ failure, dramatically manifest in the multiple organ failure syndrome. We have investigated 28 patients presenting with gross cardiovascular instability due to septic shock or haemorrhage, using standard invasive methods of monitoring (Physiological Profile). We combined this study with a computer assisted mercury-in-rubber strain gauge plethysmography (MSG) measurement, for a parallel (non-invasive) assessment of peripheral microcirculatory function. We started the investigation on patient arrival in ICU and continued it during their resuscitation regime, which essentially consisted of fluid loading together with inotropic support, where necessary. We found highly significant changes in isovolumetric venous pressure (Pvi), determined by the MSG technique, when we compared survivors (27.29 +/- 1.65 mmHg, mean +/- s.e.m.) with non-survivors (39.5 +/- 2.97 mmHg, P less than 0.001). To investigate the role of dobutamine in patient improvement we compared the Pvi values obtained from the MSG studies and demonstrated a significant decrease from the initial value (38.2 +/- 2.4 mmHg) to the final one (25.4 +/- 2.4 mmHg), obtained after weaning the patients off dobutamine. Marked cyclic changes in limb circumference (vasomotion) were also observed and their appearance correlated well with accepted parameters of cardiovascular instability. We propose that changes in both Pvi and Vm are useful indices of microvascular hypoperfusion which is probably the underlying cause of pathology in both patient groups.

Dobutamine↗