Clinical correlates of arterial lactate levels in patients with ST-segment elevation myocardial infarction at admission: a descriptive study

Introduction  

Blood lactate measurements can be used as an indicator of hemodynamic impairment and relate to mortality in various forms of shock. Little is known at the moment concerning the clinical correlates of systemic lactate in patients with ST-segment elevation myocardial infarction (STEMI).     

Stressing the critically ill patient: The cardiopulmonary and metabolic responses to an acute increase in oxygen consumption

Critically ill patients frequently have compromised respiratory and hemodynamic function. Chest physical therapy has been previously shown to increase oxygen demand and therefore was used to examine how postoperative mechanically ventilated patients responded to an increased oxygen demand. We found that during chest physical therapy, oxygen consumption increased 52% ±- 37% (SD) over baseline values. There was a 35% ±- 32% increase in oxygen extraction and a 17% ±- 33% increase in oxygen delivery. Arterial and pulmonary artery pressures also increased. The cardiac output increase was due to increased heart rate with no change in stroke volume. The increases in minute ventilation and alveolar ventilation were not sufficient to eliminate the greater quantity of carbon dioxide produced, resulting in a small increase in Paco₂. There was no significant change in systemic vascular resistance. The increase in oxygen demand caused by chest physical therapy triggered an integrated physiological response that resulted in increased respiratory and cardiac performance. This in some ways, such as the lack of increase in systemic vascular resistance, resembles the response to exercise.     

Filtration of activated granulocytes during cardiopulmonary bypass surgery: a morphologic and immunologic study to characterize the trapped leukocytes

Cardiopulmonary bypass surgery induces an inflammatory reaction among others by activation of granulocytes. Leukocyte filtration has been shown to reduce the postoperative morbidity mediated by activated granulocytes. However, little is known about the mechanism of filter-leukocyte interaction. This study examines whether a leukocyte filter removes activated granulocytes or a general leukocyte population. Eleven patients undergoing cardiopulmonary bypass surgery were included in this study. Leukocyte filtration was achieved before the reperfusion phase with a Pall non-woven polyester filter located at the venous side of the heart-lung machine. After filtration, the trapped granulocytes inside the filter were examined morphologically with light and scanning electron microscopy and immunologically by CD45RO antigen binding to the filter material. Furthermore, leukocyte release markers were measured to determine whether cells were activated during filtration. Microscopic evaluation revealed 84% granulocytes and 14% lymphocytes trapped in the filter, compared with 78% granulocytes and 22% lymphocytes in the blood before filtration. Granulocytes were trapped significantly more in the first blood contact layer of the filter material than in the middle layer and last layer, whereas lymphocytes trapped slightly more in the middle layer. The near maximum level of CD45RO expression was measured on granulocytes trapped inside the filter material, whereas CD2 and CD19 measured on lymphocytes were bound to a minor extent. Beta-glucuronidase concentration did not increase after filtration, suggesting the absence of activation of granulocytes by filtration. A leukocyte filter made of non-woven polyester material removes the activated granulocytes rather than leukocytes at random. This implies that this particular type of leukocyte removal filter is suitable for use in cardiopulmonary bypass patients whose granulocytes in the circulation are activated. Furthermore, measurement of activated granulocytes instead of total leukocyte count is likely preferable for functional assessment of leukocyte removal devices.     

Left ventricular myocardial volumes measured during arterial and delayed phases of multidetector row computed tomography: a study on intra- and interobserver variability

To compare and correlate left ventricular (LV) myocardial volumes obtained using arterial and delayed phases of multidetector row computed tomography (CT) and evaluate their intra- and interobserver variation. Two observers evaluated the arterial- and delayed-phase serial short-axis images of 45 healthy volunteers. Intra- and interobserver variations in LV myocardial volumes were correlated with four factors—myocardial volume, contrast-volume-to-body-weight ratio, and contrast-to-noise ratios in the arterial and delayed phases. Variations in the apex, mid-ventricle, and base were compared. Intra- and interobserver analyzes revealed no statistical difference and good correlation. Intra- and interobserver variations were within 5 and 10%, respectively, and were independent of the four factors. Variations were the highest at the apex. LV myocardial volumes measured using arterial- and delayed-phase cardiac CT exhibit no significant difference and good correlation. Intra- and interobserver variations are both clinically acceptable, and the apex contributes most to these variations.     

A combined approach for improving cardiopulmonary bypass in coronary artery surgery: a pilot study

BACKGROUND: This is a pilot study carried out to assess the feasibility and the clinical impact of a combined approach of cardiopulmonary bypass (CPB) with reduced anti-coagulation. METHODS: We used a retrospective, non-randomized analysis of 45 consecutive patients undergoing coronary artery bypass using standard CPB with full anticoagulation (activated clotting time, ACT, > 450 s) (Group 1; n = 23) or closed, heparin-coated CPB with low anticoagulation (ACT>250 s), precise heparin and protamine titration, controlled suction, and retrograde autologous prime (Group 2; n = 22). RESULTS: Patients were similar except for a higher incidence of three-vessel disease in Group 2 (77.3% versus 47.8%; p < 0.03). Heparin was reduced by 41% in Group 2 and protamine by 56% (p < 0.0001). Total postoperative blood loss was similar between Groups 1 and 2 (429 +/- 149 versus 435+/-168 ml, respectively). However, the operative hematocrit decrease was lower in Group 2 (-1.6 +/- 7.5% versus -6.9 +/- 4.8%; p = 0.007), although hemodilution was similar, as reflected by the blood protein level. The need for postoperative inotropic support was less frequent in Group 2 (36.4% versus 65.2%; p = 0.05). Within the subgroup of patients weaned from CPB without requiring inotropic support (n = 35), the cardiac index dropped significantly in Group 1 (p = 0.003) 6 h after the start of CPB, whereas it remained stable in Group 2 (p = 0.92). Using multivariate analyses, Group 2 was found to be more protected than Group 1 against myocardial cellular injury (p = 0.046) and need for postoperative inotropic support (p = 0.014). CONCLUSION: The pejorative postoperative outcome in coronary artery surgery was attenuated through a combined approach aimed at improving CPB.     

Left ventricular myocardial volumes measured during arterial and delayed phases of multidetector row computed tomography: a study on intra- and interobserver variability

To compare and correlate left ventricular (LV) myocardial volumes obtained using arterial and delayed phases of multidetector row computed tomography (CT) and evaluate their intra- and interobserver variation. Two observers evaluated the arterial- and delayed-phase serial short-axis images of 45 healthy volunteers. Intra- and interobserver variations in LV myocardial volumes were correlated with four factors—myocardial volume, contrast-volume-to-body-weight ratio, and contrast-to-noise ratios in the arterial and delayed phases. Variations in the apex, mid-ventricle, and base were compared. Intra- and interobserver analyzes revealed no statistical difference and good correlation. Intra- and interobserver variations were within 5 and 10%, respectively, and were independent of the four factors. Variations were the highest at the apex. LV myocardial volumes measured using arterial- and delayed-phase cardiac CT exhibit no significant difference and good correlation. Intra- and interobserver variations are both clinically acceptable, and the apex contributes most to these variations.     

Association between arterial elasticity, C-reactive protein and maximal oxygen consumption in well-trained cadets during three days extreme physical load: a pilot study

Regular aerobic training has beneficial effects on inflammatory pathways and on arterial elasticity, which are both important cardiovascular risk factors. The aim of the present study was to evaluate the effect of extreme physical load on arterial elasticity and inflammatory markers in well-trained healthy men who participated in a high-ranking combat course. Seven well-trained male cadets were examined during an international military combat course of 3.5 days duration. Small (C2) and large (C1) artery elasticity was assessed using diastolic pulse wave analysis. Inflammatory markers and arterial elasticity measurement were performed before and after the competition. The extreme prolonged physical load caused individually different responses in arterial elasticity, C-reactive protein (CRP) and creatine kinase in individual cadets. Maximal oxygen consumption (VO(2) max kg(-1)) correlated significantly with the change (Delta-difference between baseline and 24 h recovery period) of creatine kinase (r= -0.78; p=0.04) and DeltaC2 (r=0.78; p=0.04) and DeltaC1 (r=0.82; p=0.02). In multivariate analysis (R(2)=0.89, p=0.01) the DeltaC2 correlated strongly with VO(2) max kg(-1) (p=0.005) and with the DeltaCRP (p=0.03), whereas the DeltaC1 correlated only with VO(2) max kg(-1) and did not correlate significantly with the DeltaCRP. Changes in small arterial elasticity induced by extreme physical load were significantly related to VO(2) max kg(-1) and DeltaCRP, whereas the change of large artery elasticity was only associated with VO(2) max kg(-1). Our preliminary results indicate that acute exercise-induced inflammation may affect small artery elasticity. However, further, more extensive studies are needed in this area.     

Interstitial lactate levels in human skin at rest and during an oral glucose load: a microdialysis study

In vitro data have suggested that the skin is a significant lactate source. The purpose of the present study was to measure lactate and glucose concentrations in intact human skin in vivo using the microdialysis technique. Microdialysis fibres of 216 μm were inserted intradermally and perfused at a rate of 3 μl min^–1. In the first experimental protocol, dialysis fibres were calibrated by the method of no net flux in eight subjects. Skin lactate concentrations of 2·48 ± 0·17 mmol l^–1 were significantly greater than lactate concentrations of 0·84 ± 0·15 mmol l^–1 in venous plasma (P<0·01). Glucose concentrations in skin and venous plasma were similar (5·49 ± 0·18 vs. 5·26 ± 0·24 mmol l^–1). In the second experimental protocol, changes in lactate and glucose levels were studied in 10 subjects after an oral glucose tolerance test (OGTT). After the OGTT, plasma glucose and lactate levels increased by 54% and 39% to peak levels at 30 and 60 min respectively. In comparison, skin glucose and lactate increased by 41% and 18% at 60 and 90 min. No changes in skin blood flow were observed during the OGTT. The data suggest that resting skin is a significant lactate source with no significant lactate production during OGTT. The cellular source of lactate in the skin remains undetermined to date.     

Using near-infrared spectroscopy myocardial oximetry to monitor myocardial oxygen balance in a swine model of cardiac surgery: a descriptive study

Journal of Clinical Monitoring and Computing - Monitoring of the adequacy of myocardial protection with cardioplegia is nearly non-existent in clinical cardiac surgical practice and instead relies...     

Administration of hydrogen sulfide via extracorporeal membrane lung ventilation in sheep with partial cardiopulmonary bypass perfusion: a proof of concept study on metabolic and vasomotor effects

Introduction  

Although inhalation of 80 parts per million (ppm) of hydrogen sulfide (H₂S) reduces metabolism in mice, doses higher than 200 ppm of H₂S were required to depress metabolism in rats. We therefore hypothesized that higher concentrations of H₂S are required to reduce metabolism in larger mammals and humans. To avoid the potential pulmonary toxicity of H₂S inhalation at high concentrations, we investigated whether administering H₂S via ventilation of an extracorporeal membrane lung (ECML) would provide means to manipulate the metabolic rate in sheep.     

The prognostic value of blood lactate levels relative to that of vital signs in the pre-hospital setting: a pilot study

Introduction  

A limitation of pre-hospital monitoring is that vital signs often do not change until a patient is in a critical stage. Blood lactate levels are suggested as a more sensitive parameter to evaluate a patient's condition. The aim of this pilot study was to find presumptive evidence for a relation between pre-hospital lactate levels and in-hospital mortality, corrected for vital sign abnormalities.     

Resting-state brain glucose utilization as measured by PET is directly related to regional synaptophysin levels: a study in baboons

It is classically recognized that regional cerebral glucose consumption (CMRglc), as measured by positron emission tomography (PET) and [18F]-2-fluorodeoxyglucose (FDG), is a precise index of the integrated local neuronal activity. However, despite extensive use of the FDG-PET method, the significance of the measured CMRglc has been little addressed so far. In the present study, we aimed for the first time to test whether resting-state CMRglc is directly related to synaptic density. To this end, we investigated in the baboon the relationships between CMR(glc) and the levels of synaptophysin (SY), a presynaptic protein classically used to assess synaptic density. CMR(glc), measured in vivo by FDG-PET at the resting-state, and SY levels, assessed postmortem by the Western blot technique, were quantified in seven brain areas of five baboons. By applying these two techniques to the same animals, we found significant positive correlations between CMR(glc) and SY levels, across all regions and all animals, as well as within individual baboons. These findings strongly support the hypothesis that resting-state CMR(glc) reflects integrated synaptic activity.     

The strength of the ankle dorsiflexors has a significant contribution to walking speed in people who can walk independently after stroke: an observational study

Dorsch S, Ada L, Canning CG, Al-Zharani M, Dean C. The strength of the ankle dorsiflexors has a significant contribution to walking speed in people who can walk independently after stroke: an observational study.ObjectiveTo investigate the relationship between the strength of muscles of the affected lower limb and walking speed after stroke.DesignA cross-sectional observational study.SettingUniversity laboratory.ParticipantsStroke survivors (N=60; mean age ± SD, 69±11y) 1 to 6 years poststroke, able to walk 10m independently without aids.InterventionsNot applicable.Main Outcome MeasuresMaximum isometric strength of 12 muscle groups (hip flexors/extensors, adductors/abductors, internal/external rotators, knee flexors/extensors, ankle dorsiflexors/plantarflexors, invertors/evertors) of the affected lower limb was measured using hand-held dynamometry. Comfortable walking speed was measured using the ten-meter walk test.ResultsUnivariate analysis revealed that strength of the hip flexors (r=.35, P=.01), hip extensors (r=.29, P=.03), hip internal rotators (r=.30, P=.02), hip adductors (r=.29, P=.03), knee extensors (r=.27, P=.03), knee flexors (r=.30, P=.02), ankle dorsiflexors (r=.50, P=.00), ankle plantarflexors (r=.29, P=.03), and ankle evertors (r=.33, P=.01) were all positively associated with walking speed. Multivariate analysis (n=58) revealed that the combined strength of the ankle dorsiflexors and the hip flexors accounted for 34% of the variance in walking speed (P<.001). The ankle dorsiflexors accounted for 31% of the variance (P<.001).ConclusionsThe strength of muscle groups other than the lower limb extensors, particularly the ankle dorsiflexors, has an important role in determining walking speed after stroke.     

Alcohol consumption in relation to metabolic regulation, inflammation, and adiponectin in 64-year-old Caucasian women: a population-based study with a focus on impaired glucose regulation

OBJECTIVE: The aims of this study were to examine alcohol drinking patterns in women with type 2 diabetes, impaired glucose tolerance (IGT), and normal glucose tolerance (NGT) and to investigate whether alcohol intake was associated with improved insulin sensitivity, decreased biomarkers of inflammation, and increased adiponectin levels and if these effects were limited to dysmetabolic women. RESEARCH DESIGN AND METHODS: From a cohort of 64-year-old Caucasian women, 209 with type 2 diabetes, 205 with IGT, and 186 with NGT were recruited. Alcohol consumption and medication use were assessed by questionnaires. Anthropometric data were collected, and blood glucose, insulin, HDL cholesterol, triglycerides, C-reactive protein, white blood cell count, and serum adiponectin were measured. RESULTS: Compared with the NGT group, alcohol consumption was lower in the IGT group and lowest in the diabetes group. Mean alcohol intakes of >9.2 and > or =3-9 g/day were positively associated with adiponectin and insulin sensitivity (homeostasis model assessment [HOMA]), respectively, independently of obesity, metabolic control, and other confounders. Alcohol intake correlated negatively with inflammatory markers, although this did not remain after adjustment for HOMA and waist circumference. The inverse associations between alcohol consumption and factors related to the metabolic syndrome such as HOMA, waist circumference, and inflammatory markers were more obvious among women with diabetes and IGT than in healthy women. CONCLUSIONS: In these women, moderate alcohol consumption showed beneficial associations with the prevalence of type 2 diabetes, IGT, insulin sensitivity, and serum adiponectin. There is a need to clarify whether adiponectin may be a mechanistic link and also to clarify the clinical implications of these observations.     

Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease: Evaluation of different tracers,comparison to segmental systolic pressure,angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure

Summary. The skin perfusion pressure (SPP) measured as the isotope washout cessation external pressure is valuable in selection of major amputation level. Five methodological investigations important to clinical use were carried out: (1) In five normal legs and 10 legs with arterial occlusive disease (AOD), ¹³¹I-antipyrine (¹³¹1-_-a.p.) was compared to Na(¹³¹I-) and ⁹⁹Tc_m-I pertechnetate (⁹⁹Tc^m). The average SPP by ¹³¹I-_a.p. and by ¹³¹I- were approximately equal, 57·0 mmHg (range 18–93) compared to 56·3 mmHg (range 13–88) (P > 0·1). The average SPP by ⁹⁹Tc_m was just slightly higher, 60·3 mmHg (range 18–98) (P < 0·02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased in legs with arterial occlusions at two levels or more; (4) In 47 legs with AOD, the SPP on the calf or on the thigh was compared with transcutaneously measured PO₂. The two different methods correlated statistically significant, but the scatter was great; (5) During induced variations in systemic blood pressure in seven patients (12 legs with AOD), the segmental SPP and the segmental systolic blood pressure were found on average to vary in proportion with the intra-arterial mean and systolic pressure respectively; however, this proportional relationship was not valid for the individual leg. It is concluded that ⁹⁹Tc^mis as suitable as the ¹³¹I-labelled tracers in estimating the SPP. The SPP is significantly correlated to skin blood flow, to systolic blood pressure, to tc PO₂ and to angiographic findings. Correction of SPP for systemic blood pressure changes can be made in proportion with the measured variations in systemic mean blood pressure. but only for groups of patients.     

Central arterial hemodynamics in small-for-gestational-age fetuses before and during maternal hyperoxygenation: a Doppler velocimetric study with particular attention to the aortic isthmus.

OBJECTIVE: Hemodynamic changes indicating a normalization of fetal blood flow redistribution during maternal oxygen administration have been suggested to be of positive prognostic value in growth-restricted fetuses. The aortic isthmus has been suggested as a site for early detection of blood flow redistribution as well as for verification of a response to maternal hyperoxygenation. The present study was performed to investigate whether this concept could be confirmed in a study involving fetuses assumed to have only a moderate disturbance in fetoplacental hemodynamics. DESIGN AND SUBJECTS: Twenty-five singleton fetuses with an estimated weight less than -2 SD below the gestational age-related mean and without any malformation or chromosomal aberration were studied between 27 and 38 (median 34) weeks of gestation. METHODS: Velocity waveforms from the mitral valve, aortic valve, middle cerebral artery, aortic isthmus and umbilical artery were recorded before and during maternal breathing of 100% oxygen. RESULTS: Nine fetuses demonstrated absent or reversed end-diastolic velocity (ARED) in the aortic isthmus while forward flow was present in the umbilical artery. The cerebral artery pulsatility index (PI) increased with oxygen administration and there was a decrease in the aortic isthmus PI. Variables obtained from the other recording sites did not change with maternal hyperoxygenation. CONCLUSIONS: ARED in the aortic isthmus appears to be an early sign of blood flow redistribution in this group of fetuses. Maternal oxygenation results in velocity waveform changes that suggest an increase of cerebral vascular resistance and a redistribution of blood from the brain to the vascular beds supplied by the descending aorta. The aortic isthmus is a suitable site to verify this response.