[Blood changes in rats fed diets deficient in tocopherol and ubiquinone. 4. Blood picture and blood coagulation factor changes in vitamin E deficient rats following stress].
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The need to conserve a patient's own blood and avoid homologous transfusion is now well recognized. Therefore, techniques designed to reduce requirements for homologous blood transfusions have been developed. One of the methods is autotransfusion of shed mediastinal blood after open-heart surgery. The objectives of the present study were to investigate osmotic fragility and oxygen transport capacity of shed mediastinal blood compared to patient blood and stored packed red blood cells (SAGM). Shed mediastinal blood from ten consecutive patients undergoing elective cardiac surgery (coronary bypass grafting) was studied and compared to patient blood, 10 units of 3 weeks old and 10 units of 5 weeks old stored packed red blood cells (SAGM). Oxygen transport capacity was investigated by calculation of p50 for oxygen by use of the oxygen status algorithm (OSA 2.0) programme and measurement of 2,3-diphosphoglycerate (2,3-DPG) concentrations. The osmotic fragility was determined using increasing concentrations of saline. 2,3-DPG concentrations in shed mediastinal blood (5.3 mikromol/ml erythrocyte) were within the range measured in patient blood, but significantly higher than SAGM blood (P < 0.001). P50 for oxygen (3.5 kPa) in shed mediastinal blood was not significantly different compared to patient blood, but significantly higher (P < 0.01) compared with stored SAGM blood. The osmotic fragility in shed mediastinal blood was not significantly different compared to patient blood, but significantly lower (P < 0.001) than the osmotic fragility in stored SAGM blood. This suggests that red cells saved from shed mediastinal blood have better oxygen transport capacity and may have longer survival compared to stored blood.
OBJECTIVE: Nocturnal non-invasive ambulatory blood pressure monitoring inevitably causes an undesirable external stimulus due to the cuff pressure and, for some monitors, disturbing compressor sound. The objective of the present study was to determine whether non-invasive automated blood pressure monitoring during sleep provokes arousal and changes in blood pressure and/or heart rate. DESIGN: Sleep response and blood pressure reaction during and immediately after blood pressure monitoring were studied by means of simultaneous electroencephalography and blood pressure recordings. METHODS: Blood pressure and electroencephalogram were recorded simultaneously in 24 subjects (10 hypertensive, 14 normotensive). Blood pressure was registered with a non-invasive automatic blood pressure monitor every 20 min. Inflation and deflation of the cuff were registered on one of the electroencephalogram channels by means of a small pressure meter attached to the cuff. For each subject, blood pressure during uninterrupted sleep was compared with that during arousal provoked by the recordings. RESULTS: Blood pressure recording caused an arousal in 67% of the recordings. During 33% of the recordings, sleep continued. Neither systolic nor diastolic blood pressure differed significantly for recordings during 'uninterrupted sleep' when compared with arousal. Heart rate was significantly faster during arousal than during uninterrupted sleep. Analysed separately, hypertensive subjects showed an overall blood pressure response close to that of normotensive subjects. There was a significant trend towards lower blood pressure, parallel with deeper sleep. CONCLUSIONS: The results of this study show that non-invasive ambulatory blood pressure monitoring during sleep accurately records basal blood pressure and can distinguish blood pressure during superficial sleep from blood pressure during deep sleep. Sleep is often disturbed by blood pressure monitoring but, irrespective of whether recording provokes arousal, monitored blood pressure is the same.
BACKGROUND: Patients with elevated clinic blood pressure and normal ambulatory blood pressure have a better prognosis than patients with sustained ambulatory hypertension, and may not have to be treated with antihypertensive drugs. On the contrary, current guidelines emphasize repeated clinic blood pressure measurements for the initiation of antihypertensive therapy. OBJECTIVE: To examine the relationship between ambulatory blood pressure at baseline and clinic blood pressure after 6 months of follow-up in untreated hypertensive patients, and the relationships of these pressures with the subsequent incidence of cardiovascular events. METHODS: Patients who were > or = 60 years old, with systolic clinic blood pressure of 160-219 mmHg and diastolic pressure < 95 mmHg, participated in the Systolic Hypertension in Europe trial. The relationship between ambulatory blood pressure at baseline and clinic blood pressure after 6 months of follow-up was examined in 295 patients enrolled in the Ambulatory Blood Pressure Monitoring substudy and randomized to the placebo arm, and who were still on double-blind treatment and not taking other antihypertensive drugs after 6 months follow-up. RESULTS: Age averaged 70 +/- 6 years, 41% were men, and baseline daytime ambulatory blood pressure was 152 +/- 16/84 +/- 10 mmHg; clinic blood pressure decreased from 173 +/- 10/86 +/- 6 mmHg at baseline to 163 +/- 20/85 +/- 9 mmHg at month 6. Systolic daytime ambulatory blood pressure at baseline and systolic clinic blood pressure at month 6 were considered normal if < 140 mmHg. Of the 74 patients with normal systolic daytime ambulatory blood pressure at baseline, only seven (9.5%) had a normal systolic clinic blood pressure during follow-up. Conversely, of the 24 patients with normal follow-up clinic blood pressure, only seven (29%) had a normal systolic daytime ambulatory blood pressure at baseline. The incidence of cardiovascular events beyond the 6-month visit was significantly related to baseline ambulatory blood pressure but not to follow-up clinic pressure. CONCLUSIONS: Baseline daytime ambulatory blood pressure and follow-up clinic blood pressure do not identify the same patients for antihypertensive treatment. Baseline ambulatory pressure is a better predictor of cardiovascular events than follow-up clinic pressure.
OBJECTIVE: To evaluate selected hemodynamic, blood gas, and biochemical responses to mild to moderate acute blood loss in standing, awake horses. DESIGN: Prospective study. ANIMALS: 7 healthy mares. PROCEDURES: Each horse was restrained in standing stocks, and its head was maintained in a neutral position; sedatives and tranquilizers were not administered. During a 1-hour period, blood was collected into collection bags by use of a suction pump. The rate of blood collection was approximately 16 mL/kg/h (7.3 mL/lb/h). Thirty minutes after blood collection, the blood was readministered at the same rate. Central venous pressure (CVP), central venous blood gas, blood lactate concentration, and heart rate were measured at baseline (after placement of catheters), after removal of blood, and after readministration of blood. RESULTS: In response to blood loss, CVP decreased and blood lactate concentration increased significantly, compared with baseline values; heart rate and results of central venous blood gas analysis did not change significantly. After readministration of blood, CVP returned to baseline value and blood lactate concentration approached baseline value. CONCLUSIONS AND CLINICAL RELEVANCE: Changes in CVP and blood lactate concentration appear to be early indicators of hypovolemia in horses, which may represent acute blood loss in trauma patients; these variables should be monitored to assess the potential need for blood transfusions. These variables can be used to monitor responses of horses to blood transfusions when whole blood is administered as the replacement fluid.
PURPOSE: Allogeneic blood transfusions have reportedly been associated with a poor prognosis in patients with curatively resected cancer. To control for immunosuppression induced by a speculatively causal allogeneic blood transfusion, we designed a randomized study in which the control group received autologous blood transfusions not related to any condition of immunosuppression. PATIENTS AND METHODS: One hundred twenty patients with potentially curative resectable colorectal cancer and the capability to predeposit autologous blood were randomly selected to receive either standard allogeneic blood transfusion or predeposited autologous blood. RESULTS: In curatively resected cancer patients, the number who needed allogeneic blood transfusions was reduced from 60% in the allogeneic blood group to 33% in the autologous blood group (P = .009). After a median follow-up duration of 22 months (range, 8 to 48) tumor recurrence was observed in 28.9% of the allogeneic blood group and 16.7% of the autologous blood group. Life-table analysis established a tendency toward a shorter tumor-free survival for the allogeneic blood group (log-rank P = .11). The problem with this analysis was the strong association of allogeneic blood transfusions with tumor recurrence, which interfered in 33% of patients in the autologous blood group who required additional allogeneic blood transfusions. Multivariate analysis of established risk factors for tumor recurrence and surgery-related variables reflecting potential immunosuppressive conditions showed that only pT stage (relative risk, 6.61; 95% confidence interval [CI], 1.82 to 23.99; P = .004), pN stage (relative risk, 8.39; 95% CI, 3.15 to 22.33; P < .001), and the need for allogeneic blood (relative risk, 6.18; 95% CI, 2.20 to 17.37; P < .001) were independent predictors of tumor recurrence. Subgroup analysis of patients who received a transfusion of < or = 2 U blood found a significantly higher risk of tumor recurrence in the allogeneic blood group (relative risk, 5.16; 95% CI, 1.13 to 23.62; P = .034), which was reduced to borderline significance (relative risk, 3.54; 95% CI, 0.76 to 16.51; P = .107) by adjustment for tumor (T) and node (N) stage. CONCLUSION: As indicated by these first results, the blood transfusion modality has a significant effect on tumor recurrence after surgical treatment of colorectal cancer. A change in the practice of blood transfusion might thus potentially surpass the impact of any recent adjuvant treatment strategies.
A previous investigation suggested that the use of plasma as the biological fluid for measurement of amphotericin B (AmpB) concentrations greatly underestimates the concentrations of AmpB in the total blood circulation following amphotericin B lipid complex (ABLC) administration to humans. The purpose of this study was to determine if differences in the method used to obtain plasma from whole blood influences the percentage of AmpB recovered in plasma following ABLC incubation in whole blood. ABLC (5 microg AmpB/ml; peak blood concentration observed in rabbits following intravenous bolus of ABLC at a dose of 1 mg/kg) was incubated in whole blood for 5 min at 25 degrees C. These conditions were used to mimic the sample retrieval conditions used when blood is obtained from animals and human patients. Following incubation, plasma was obtained from whole blood using five different methods: (A) Whole blood was centrifuged for 5 min at 23 degrees C, and the plasma was separated; (B) whole blood was stored at 4 degrees C for 18 h, and the plasma was separated by gravity; (C) whole blood was stored at 23 degrees C for 18h, and the plasma was separated by gravity; (D) whole blood was stored at 37 degrees C for 18 h in a water bath, and the plasma was separated by gravity; and (E) whole blood was stored at 30 degrees C for 18 h in a water bath, and the plasma was separated by gravity. All samples were protectedfrom light throughout the duration of the experiment. AmpB concentration in each plasma sample was determined by high-performance liquid chromatography (HPLC) using an external calibration curve. The whole blood:plasma Amp B concentration ratio and the percentage of AmpB partitioned into plasma following incubation of ABLC in whole blood for each plasma separation procedure was as follows: (A) 6.5:1 blood:plasma AmpB concentration ratio, 15.4% +/- 1.6% AmpB in plasma; (B) 2.98:1 blood:plasma AmpB concentration ratio, 33.6% +/- 7.7% AmpB in plasma; (C) 1.5:1 blood:plasma AmpB concentration ratio, 67.6% +/- 10.3% AmpB in plasma; (D) 1.5:1 blood : plasma concentration ratio, 68.1% +/- 1.1% AmpB in plasma; and (E) 1.2 : 1 blood:plasma AmpB concentration ratio; 83.4% +/- 5.5% AmpB in plasma. These findings suggest that when measurement of AmpB in plasma is required following ABLC administration, incubation of whole blood at 30 degrees C for 18 h appears to be the most effective method.
BACKGROUND: In validation studies reporting on the accuracy of blood pressure measuring devices (ambulatory and non-ambulatory systems), it is frequently stated that the accuracy of blood pressure devices seems to decrease at increasing blood pressure levels. This has been shown for several ambulatory devices in the past. Whether more recently validated devices are less accurate at increasing blood pressure levels is unknown, however. OBJECTIVES: We therefore retrospectively searched the literature for studies performed between 1993 and 2003, reporting on the accuracy of blood pressure measuring devices over different blood pressure levels. When needed, additional information from the authors was requested. METHODS: In total, 30 studies were selected. Of these, the studies reporting on the accuracy of 14 different ambulatory and nine different non-ambulatory devices were useful. For both ambulatory and non-ambulatory devices, accuracy appeared to decrease at increasing blood pressure levels. This was particularly shown for systolic blood pressure. RESULTS: We speculate whether this finding is due to the oscillometric method of blood pressure measurement. Another explanation may exist, however. Blood pressure variability increases with higher blood pressure. Further, the British Hypertension Society protocol 1993 uses sequential measurements. This may be the reason that, owing to the increased blood pressure variability, the accuracy of most devices tends to decrease at higher blood pressure levels. Consequently, the accuracy of blood pressure measuring devices may be underestimated at higher blood pressure levels. CONCLUSION: Currently used automated blood pressure measurement devices seem to be less accurate at increasing blood pressure levels. It is important to be aware of this phenomenon when treating hypertensive patients. The reported decrease in accuracy, however, may well be explained by the increasing blood pressure variability at increasing blood pressure and the use of sequential measurements. If this is the case, then the accuracy of these devices is perhaps underestimated.
BACKGROUND: We compared the sensitivity of office blood pressure and ambulatory blood pressure monitoring recordings in evaluating the effectiveness of antihypertensive treatment and identified factors related to inadequate blood pressure control among hypertensive stroke survivors. METHODS: Office blood pressure and ambulatory blood pressure monitoring measurements were performed at 120+/-30 days after ictus in 187 first-ever consecutive hypertensive stroke survivors who were receiving blood pressure-lowering medications according to international guidelines. Handicap was assessed by the modified Rankin Scale. Blood pressure was regarded as controlled if office and daytime ambulatory systolic and diastolic blood pressure values were <140/90 and <135/85 mmHg, respectively. Patients were subclassified according to the degree of their nocturnal systolic blood pressure fall [(mean daytime values-mean night-time values)100/mean daytime values] as dippers (>or=10%), nondippers (>or=0% and <10%) and reverse dippers (<0%). RESULTS: Effective blood pressure control was documented in significantly (P<0.001) fewer patients using ambulatory blood pressure monitoring (32.1%) than those using office recordings (43.3%), whereas in 16% of the study population a masked lack of per-treatment blood pressure control (elevated ambulatory blood pressure in the presence of normal office blood pressure levels) was identified. The distribution of dipping patterns differed significantly (P=0.01) between controlled hypertensive individuals (normal office and ambulatory measurements) and patients with isolated ambulatory hypertension (dippers: 31.3 vs. 10.0%; nondippers:56.9 vs. 53.3%; reverse dippers: 11.8 vs. 36.7%). Logistic regression analysis revealed diabetes mellitus and functional independency (modified Rankin Scale score<2) as independent predictors of inadequate blood pressure control. CONCLUSION: Ambulatory blood pressure monitoring detects a substantial number of treated hypertensive stroke survivors with a masked lack of per-treatment blood pressure control, who present a higher prevalence of abnormal circadian blood pressure patterns (reverse dipping). Diabetes mellitus and poststroke functional independency are the main factors contributing to inadequate blood pressure control.
STUDY OBJECTIVE: To demonstrate the utility of a new blood-conserving arterial line system in reducing blood loss associated with blood drawing in the critical care setting. DESIGN: Prospective, randomized, crossover comparison between two arterial line systems. SETTING: Medical intensive care unit (ICU); tertiary care teaching institution. PATIENTS: Thirty-one patients who required invasive arterial blood pressure monitoring throughout their ICU course. INTERVENTIONS: For ICU days 1 to 2, patients were randomized to receive either a conventional arterial line system or a new blood-conserving arterial line system. On ICU days 3 to 7, patients with a conventional arterial line were crossed over to the blood-conserving arterial line, and vice versa. Laboratory blood volumes, mixed discard volumes, and blood discard volumes were then recorded to document how much blood loss is associated with each aspect of the blood sampling process. RESULTS: The mean total volume of blood sent to the laboratory for testing was 257.4 ml. As a result of "clearing the line" over the 7-day period, patients with the conventional arterial line system lost a mean volume of 340.2 ml of blood mixed with heparinized saline solution more than patients with the blood-conserving arterial line. In terms of the blood component of the blood-heparinized saline solution mixture, use of the conventional arterial line was associated with an average of 156.8 ml more blood discarded than with the blood-conserving arterial line. CONCLUSION: The new blood-conserving arterial line system provides a simple and effective method for reducing blood loss related to diagnostic sampling in the critical care setting.
OBJECTIVE: To study the suitability of diagnosis-related groups (DRGs) to quantify blood use in order to fund hospitals directly for fresh blood components. DESIGN: (i) Retrospective empirical analysis of hospital inpatient separation data, matching DRG classification with blood usage. (ii) Prediction of blood usage based on actual DRGs and comparison with actual blood products issued from the blood service. SETTING: Eight large public hospitals, April 1994-March 1995, the Department of Human Services and the Australian Red Cross Blood Service in Victoria, 1994-1997. MAIN OUTCOME MEASURES: Requirement for transfusion according to DRG; quantity of blood or blood products transfused; and statistical reliability of measuring blood component usage by DRG. RESULTS: A match between patient records and transfusion records for 287,117 patient separations showed that the patients had received 51,115 units of red cells, 30,451 units of platelet concentrates, 9043 units of fresh frozen plasma and 1273 units of cryoprecipitate. Ten per cent of DRGs (527) accounted for over 70% of blood product usage. The numbers of DRGs in which blood products were used for at least 30 separations (with a relative SEM [for units of blood used per separations using blood] of up to 20% at a 95% confidence level) were 56 for red cells, 8 for platelets and 4 for fresh frozen plasma. Estimates of red cell usage calculated from actual DRGs for three consecutive years (1994-1997) showed that DRGs predicted aggregate issues of red cells by the Red Cross Blood Service (ratio of actual red cells issued to red cell usage estimates were 1.036 for 1994-95, 0.994 for 1995-96, and 1.021 for 1996-97, respectively). CONCLUSION: DRGs are moderately good predictors of blood product usage, and could be used to allocate funds for blood products to hospitals instead of to the blood service. However, DRG data are not designed to manage blood issue policies, because DRGs do not represent single diagnoses or procedures and some are surrogate descriptions of procedures.
Designated or directed blood transfusion (DD) is a controversial practice; its merits are currently debated on the basis of implications for the national blood supply and on the "safety" of directed blood compared with homologous blood. An equally compelling issue for the merits of DD is whether this practice results in its putative effect: to avoid volunteer homologous blood exposure. To study this, the authors reviewed 112 consecutive patients (73 orthopedic) who predeposited autologous blood for elective surgery. This group was compared with 17 patients (all orthopedic) who predeposited autologous blood and also requested storage of designated blood. Seven of 17 patients with DD subsequently received homologous blood, compared with 11 of 112 patients without designated blood (NDD, P less than 0.01) and 3 of 35 NDD orthopedic patients asked to predonate three or more units of blood, P = 0.015. DD and NDD patients were no different when analyzed for age, sex, or units blood stored; admission, nadir, or discharge hematocrit; autologous blood transfused; days in hospital; or surgical blood loss. The authors conclude that patient requests for DD are unjustified for elective surgical patients who are eligible to donate autologous blood because DD as practiced in this setting does not avoid subsequent homologous blood exposure. Maximizing autologous blood procurement is the preferred alternative for avoiding homologous blood transfusion.
Morphological evidence of the potential for adsorptive transcytosis of protein through the mammalian blood-brain fluid barriers, first reported from this laboratory in the mouse, has been confirmed and expanded upon in rats injected intravenously or into the lateral cerebral ventricle/subarachnoid space with with exogenous lectin wheatgerm agglutinin (WGA) conjugated to horseradish peroxidase (HRP). Blood-borne WGA-HRP rapidly enters cerebral endothelia by the process of adsorptive endocytosis and labels the vascular tree throughout the CNS. At 3 h post-injection and longer, WGA-HRP occupies the perivascular clefts and labels perivascular cells and basal lamina; this suspected transendothelial transfer of the lectin conjugate from blood to brain involves specific constituents of the endothelial endomembrane system of organelles (e.g., plasmalemma, vesicles, endosomes, Golgi complex). Within 6 h, reaction product is evident in extracellular clefts beyond the perivascular basal lamina and labels endocytic vesicles, endosomes, and dense bodies within cells and processes of the neuropil. Exposure of the abluminal surface of blood-brain barrier endothelia for 1-18 h to WGA-HRP delivered into the cerebral ventricles or subarachnoid space indicates blood-brain barrier endothelia do not engage in demonstrable adsorptive endocytosis at the abluminal surface. In this preparation, no endothelial organelles comparable to those sequestering blood-borne WGA-HRP are labelled with the lectin conjugate; hence, significant adsorptive transcytosis of WGA-HRP through cerebral endothelia from brain to blood is unlikely. The demonstrable difference in membrane internalization of the luminal versus abluminal plasmalemma of blood-brain barrier endothelia suggests the blood-brain barrier is polarized regarding adsorptive endocytosis of WGA-HRP. If adsorptive transcytosis of macromolecules through the blood-brain barrier does occur, the process appears unidirectional, from blood to brain but not from brain to blood. Absence of demonstrable endocytosis at the abluminal front is an enigma in the scheme of transcytosis through the blood-brain barrier from blood to brain insofar as exocytosis and endocytosis are complementary events in the cellular secretory process. This unconventional membrane behavior associated with the abluminal plasmalemma argues against a significant transcytosis of blood-borne protein through blood-brain barrier endothelia. The potential for transcytosis of macromolecules through the blood-cerebrospinal fluid barrier of choroid plexus epithelia is not as problemmatic as that through blood-brain barrier endothelia; additional evidence is provided to suggest choroid plexus epithelia participate in adsorptive endocytosis circumferentially and adsorptive transcytosis of WGA-HRP bidirectionally between the blood and cerebrospinal fluid.
OBJECTIVE: To assess the ability of limited ambulatory blood pressure monitoring as a valid replacement for office blood pressure measurement done to American Heart Association criteria in diagnosing hypertension. METHODS: In all, 105 adults, who had been referred for limited ambulatory blood pressure monitoring, participated in the study. Limited ambulatory blood pressure monitoring consisted of 6 h of blood pressure measurement while ambulatory at the Mayo Clinic, using a SpaceLabs 90207 (SpaceLabs Medical, Issaquah, Washington, USA) collecting six readings per hour for the period of observation. The study participants gave consent for three additional consecutive office blood pressure measurements, using a validated aneroid device, done to American Heart Association criteria, by a single hypertension nurse specialist. RESULTS: Mean systolic blood pressure by limited ambulatory blood pressure monitoring was 137.9+/-14.2 mmHg and for the nurse, 137.9+/-20.1 mmHg. Mean diastolic blood pressure by limited ambulatory blood pressure monitoring was 81.5+/-9.7 mmHg and for the nurse, 74.3+/-11.9 mmHg. The intermethod difference for systolic blood pressure was 0.03+/-12.5 mmHg and diastolic blood pressure, -7.2+/-8.0 mmHg. Using <140/90 as criteria factor, limited ambulatory blood pressure monitoring and the trained nurse agreed 77% of the time on whether the patient was hypertensive. This agreement increased to 81% if the participant's referral blood pressure was >or=140/90. CONCLUSIONS: Limited ambulatory blood pressure monitoring is an excellent replacement for office blood pressure, done to American Heart Association criteria, in diagnosing hypertension. This avoids issues of variability introduced by the observers, such as digit preference and bias, and increases reproducibility of blood pressure measurements. The appropriate normal value for limited ambulatory blood pressure monitoring is <140/90 mmHg compared with <135/85 mmHg used in 24-h ambulatory blood pressure monitoring.