Acid-base Values Research Articles

Short Term Propofol Anaesthesia Is Not Associated with an Increase in Blood Lactate: A Comparative Study with Sevoflurane

This research was conducted considering the fact that today, there are still very few studies comparing Sevoflurane or Target Controlled Infusion using Propofol in term of serum lactate accumulation during general anaesthesia. There were 92 patients aged 18-65 years old, classified under ASA I, were involved in this prospective study. They were divided into 2 groups and this study was done in a double-blind manner. Patients received either Sevoflurane inhalational or Propofol infusion using Marsh model (target plasma concentration of 5 mcg/ml) during operation. All the patients received anaesthesia in a standard practice and blood samples were taken at every hour until completion of operation. The blood samples were tested for acid-base values and lactate level. There are significant differences in the mean values of serum lactate levels at 1st, 2nd, 3rd and 4th hour of surgery within propofol and sevoflurane group with p value of < 0.05. Nevertheless, when comparing differences in the mean values of serum lactate levels between propofol and sevoflurane group showed no significant difference of serum lactate change with p=0.186. In conclusion, our study shows that short term anaesthesia with sevoflurane is associated with an increase blood lactate levels more than lactate levels observed during high dose propofol anaesthesia.

Acid base, electrolyte, glucose, and lactate values during cardiopulmonary resuscitation in dogs and cats.

To report acid base, electrolyte, glucose, and lactate values collected during or immediately after cardiopulmonary resuscitation (CPR) in dogs and cats. Retrospective study. University Teaching Hospital. Thirty-two dogs and 10 cats. None. Blood gas, electrolyte, glucose, and lactate values measured during CPR or within 5 minutes of return of spontaneous circulation (ROSC) were retrospectively evaluated. The time of blood collection with respect to the occurrence of cardiopulmonary arrest (CPA), the initiation of CPR or ROSC was noted. Forty-two venous blood samples were analyzed, 24 collected during CPR and 18 samples were collected within 5 minutes of ROSC. Metabolic acidosis and hyperlactatemia were evident in all samples in the study while an increased PvCO2 occurred in 88% of samples collected during CPR and in 61% of samples collected following ROSC. Hyperkalemia occurred in 65% of all cases, decreased ionized calcium was evident in 18%, hypoglycemia was evident in 21% while hyperglycemia was evident in 62%. There was no significant difference in any parameter evaluated between dogs and cats during CPR. There was no significant difference of any variable measured during the first 15 minutes of CPA versus those measured more than 15 minutes following CPA. When the values measured during the first 5 minutes of ROSC were compared to those measured during CPR, the pH and PvO2 were significantly lower in the CPR group. Biochemical abnormalities including metabolic acidosis, hyperkalemia, ionized hypocalcemia, hypoglycemia, and hyperglycemia can be identified during CPR and immediately following ROSC. The therapeutic and prognostic relevance of these changes are yet to be defined and may prove to be useful to guide patient management in the future.

Effect of syringe type, storage temperature and time delay on venous blood gas values in newborn calves

The effects of storage temperature, storage duration and the type of syringe on blood gas and acid–base values in blood of newborn calves were investigated using commercial blood gas syringes coated with heparin (Monovette blood gas syringe, Mono) or heparinised injection syringes (HS). The pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), base excess (BE), bicarbonate concentration, oxygen saturation (sO2), total carbon dioxide (TCO2) and l-lactate concentration were determined immediately after blood collection. In addition, venous blood from 30 calves collected immediately after birth was stored for 12 h at 4 and 18 °C. Means that differed from baseline by more than ±3 SD of the intraserial precision of the blood gas analyser were considered effects of blood storage. There were very strong correlations between the two syringe types for pH, BE, bicarbonate concentration, TCO2 and l-lactate concentration in blood assessed immediately after collection. The difference between the mean and baseline of pO2 exceeded ±3 SD after 20 min of storage at 4 °C and after 180 min at 18 °C. At those time points, the means of pH and l-lactate concentration were also outside the ±3 SD range. In blood stored in HS, means exceeded the ±3 SD range after 120 min for l-lactate, after 180 min for pH and after 360 min for the pCO2, pO2, BE and bicarbonate concentration. Storage of venous blood samples at 4 °C preserved blood gas values except for pO2. With the exception of l-lactate measurement, heparinised syringes are useful for storage of the blood at room temperature for up to 3 h.

Determination of pH Value and Acid-base Property of Ionic Liquid Aqueous Solutions

The ionic liquids (ILs) and their aqueous solutions have been considered as a new generation of absorption working substances for applications in gas separation and absorption refrigeration processes. It is important to understand the physicochemical properties of ionic liquids in aqueous solutions, such as chemical potential and acid-base properties before any industry application. In this study, we focused on the acid-base properties of the IL aqueous solutions by testing the pH values of the aqueous solutions of two ionic liquids, 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) and 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl). All the tests were carried out at 25 and in a well controlled dry air °C surrounding. There were 16 water mass fractions for each of [EMIM]Ac and [HMIM]Cl aqueous solutions tested in range of 0.04 to 0.95 and 0.01 to 0.96, respectively. There, two methods, the sophisticated pH paper and the pH meter, were applied for the tests and the differences between the two test methods were detected. The test data from the two test methods and their differences were then evaluated with an aggregation film model and the activity theory for the film and aqueous solution phases. The results show that the difference of the pH values tested by the two methods is significant. The pH data from the sophisticated pH paper test present the bulk acid-base property of the IL aqueous solutions, while the pH meter can only reflect the hydrogen ion concentration in the IL aggregation film which was formed on the surface of the electrode of the pH meter. With analysis of acid-base reaction in the IL aqueous solution, a calculation model for the pH value of the bulk solution region was developed, and the data of the sophisticated pH paper test were correlated and the solution acid-base values were obtained. Based on analysis of the water species equilibrium in the IL aggregation film and the bulk aqueous solution phases and its effect on the concentration of hydrogen ions in the aggregation film, a method for calculation of the difference of pH values between the aggregation film and the bulk solution was proposed and the data from the pH meter were then fitted with the proposed calculation method. The results provide experimental data and a quantitative method for analysis of the acid-base property of IL aqueous solution systems.

Evaporation of free water causes concentrational alkalosis in vitro

The development of metabolic alkalosis was described recently in patients with hypernatremia. However, the causes for this remain unknown. The current study serves to clarify whether metabolic alkalosis develops in vitro after removal of free water from plasma and whether this can be predicted by a mathematical model. Ten serum samples of healthy humans were dehydrated by 29 % by vacuum centrifugation corresponding to an increase of the contained concentrations by 41 %. Constant partial pressure of carbon dioxide at 40mmHg was simulated by mathematical correction of pH [pH(40)]. Metabolic acid-base state was assessed by Gilfix' base excess subsets. Changes of acid-base state were predicted by the physical-chemical model according to Watson. Evaporation increased serum sodium from 141 (140-142) to 200 (197-203) mmol/L, i.e., severe hypernatremia developed. Acid-base analyses before and after serum concentration showed metabolic alkalosis with alkalemia: pH(40): 7.43 (7.41 to 7.45) vs 7.53 (7.51 to 7.55), p = 0.0051; base excess: 1.9 (0.7 to 3.6) vs 10.0 (8.2 to 11.8), p = 0.0051; base excess of free water: 0.0 (- 0.2 to 0.3) vs 17.7 (16.8 to 18.6), p = 0.0051. The acidifying effects of evaporation, including hyperalbuminemic acidosis, were beneath the alkalinizing ones. Measured and predicted acid-base changes due to serum evaporation agreed well. Evaporation of water from serum causes concentrational alkalosis in vitro, with good agreement between measured and predicted acid-base values. At least part of the metabolic alkalosis accompanying hypernatremia is independent of renal function.

Association between umbilical cord artery pCO2 and the Apgar score; elevated levels of pCO2 may be beneficial for neonatal vitality after moderate acidemia

To determine the association between 5-min Apgar score and umbilical cord artery carbon dioxide tension (pCO₂). Observational study. European hospital labor wards. Data from 36,432 newborns ≥36 gestational weeks were obtained from three sources: two trials of monitoring with fetal electrocardiogram (the Swedish randomized controlled trial and the European Union Fetal ECG trial) and Mölndal Hospital data. After validation of the acid-base values, 25,806 5-min Apgar scores were available for analysis. Validation of the umbilical cord acid-base values was performed to obtain reliable data. 5-min Apgar score was regressed against cord artery pCO₂ in a polynomial multilevel model. Five-min Apgar score, umbilical cord pCO₂, pH, and base deficit. Overall, a higher cord artery pCO₂ was found to be associated with lower 5-min Apgar scores. However, among newborns with moderate acidemia, lower umbilical cord artery pCO₂ (≤median pCO₂ for the specific cord artery pH) was associated with lower 5-min Apgar scores, with a relative risk of 2.0 (95% confidence interval: 1.4-2.8) for 5-min Apgar scores 0-6. Metabolic acidosis affects the newborn's vitality more than respiratory acidosis. In addition, elevated levels of pCO₂ may be beneficial for fetuses with moderate acidemia, and thus cord artery pCO₂ is a factor that should be considered when assessing the compromised newborn.

Haematological, blood gas and acid–base values in the Galgo Español (Spanish greyhound)

Haematologic profiles, electrolyte concentrations, blood gas values and acid-base balance have been studied and reported in healthy greyhounds; however, there is only one study published on blood gas values in Galgos Españoles. Because of their purported common origins with greyhounds (same group and class), it was hypothesised that Galgos Españoles also have differences in haematologic values, electrolyte concentrations, blood gas values and acid-base balance compared to other non-sporting breeds. Venous blood samples from 30 Galgos Españoles and 20 dogs from different breeds were collected, and complete blood counts, electrolyte concentrations, blood gas values and acid-base balance were measured. From the 24 parameters analysed, 5 had statistically significant differences (P<0·05). Galgos Españoles had higher haematocrit (P<0·001), haemoglobin concentration (P=0·003), erythrocyte count (P=0·016) and pH (P=0·03), and lower platelet count (P=0·005), than those in other-breed dogs. These results confirm that significant haematologic differences exist in Galgos Españoles when compared with other dogs, although these differences are not as striking as in greyhounds. Practitioners need to be aware of these breed-specific differences in order to make accurate diagnoses in Galgos Españoles.

Effects of syringe type and storage conditions on results of equine blood gas and acid-base analysis

To determine effects of syringe type and storage conditions on blood gas and acid-base values for equine blood samples. Blood samples obtained from 8 healthy horses. Heparinized jugular venous blood was equilibrated via a tonometer at 37°C with 12% O(2) and 5% CO(2). Aliquots (3 mL) of tonometer-equilibrated blood were collected in random order by use of a glass syringe (GS), general-purpose polypropylene syringe (GPPS), or polypropylene syringe designed for blood gas analysis (PSBGA) and stored in ice water (0°C) or at room temperature (22°C) for 0, 5, 15, 30, 60, or 120 minutes. Blood pH was measured, and blood gas analysis was performed; data were analyzed by use of multivariable regression analysis. Blood Po(2) remained constant for the reference method (GS stored at 0°C) but decreased linearly at a rate of 7.3 mm Hg/h when stored in a GS at 22°C. In contrast, Po(2) increased when blood was stored at 0°C in a GPPS and PSBGA or at 22°C in a GPPS; however, Po(2) did not change when blood was stored at 22°C in a PSBGA. Calculated values for plasma concentration of HCO(3) and total CO(2) concentration remained constant in the 3 syringe types when blood was stored at 22°C for 2 hours but increased when blood was stored in a GS or GPPS at 0°C. Blood samples for blood gas and acid-base analysis should be collected into a GS and stored at 0°C or collected into a PSBGA and stored at room temperature.

Maternal and perinatal complications by day of gestation after spontaneous labor at 40-42 weeks of gestation

To evaluate pregnancy outcome after spontaneous labor by day of gestation between 40(+0) and 41(+6) weeks of gestation. Evaluation of prospectively collected labor ward data. University Hospital, Denmark. Unselected consecutive cohort of 14 678 spontaneously starting deliveries between 280 and 293 days of gestation during the years 2000-2006. Data were registered in a computer program after each delivery by a midwife and the entries further evaluated by a specialist in obstetrics. Complication rates were compared using Fisher's exact test. Maternal complication rates for each gestation day, including cesarean delivery, maternal blood transfusion, episiotomy, operative vaginal delivery, third and fourth degree perineal lacerations and perinatal morbidity. The cesarean delivery rate increased from 6% on day 280 to 11% on day 293. Cesarean delivery increased from 40 to 41 weeks gestation (7.3 vs. 9.5%, p<0.005), as did maternal transfusion (0.5 vs. 1.2%, p<0.001) and cesarean section on the indication fetal distress (1.5 versus 2.4%, p<0.005), but perineal lacerations did not. Likewise, there was an increase in episiotomy rates (3.0 vs. 3.5%, p=0.08), operative vaginal delivery (5.8 vs. 6.5%, p=0.07) and admission to neonatal intensive care (1.4 versus 2.0%, p=0.009), but no increase in 5 minute Apgar scores <7 or low umbilical artery acid-base values. Deliveries starting spontaneously in an unselected cohort showed an increase in maternal complications, meconium-stained amniotic fluid and admission to the neonatal intensive care unit.

Relation between umbilical cord blood pH, base deficit, lactate, 5‐minute Apgar score and development of hypoxic ischemic encephalopathy

Umbilical cord acid-base analysis is fundamental for assessing intrapartum hypoxia. The accuracy of arterial umbilical cord blood lactate, pH and base deficit to reflect a low 5-minute Apgar score and hypoxic ischemic encephalopathy (HIE) stage 2-3 was assessed, and new gestational age-adjusted reference standards were compared with traditional stationary reference values. A total of 13,735 pH-validated routine cord acid-base values from singleton deliveries were tested with stationary and gestational age-adjusted reference values using receiver operating characteristic curves and calculation of area under curve. University hospital. Accuracy of low pH, high base deficit and high lactate, alone or in combination, to imply 5-minute Apgar score < 7 or < 4 or HIE. Gestational age-adjusted values were for all parameters significantly better than crude values to indicate Apgar score < 7. For Apgar score < 4, the differences were not significant. The frequency of HIE was 0.046%, making statistical analyses pointless. Gestational age-adjusted lactate had the overall best accuracy and among combinations; a low age-adjusted pH plus high age-adjusted lactate was slightly better than a low age-adjusted pH plus high age-adjusted base deficit. The sensitivity and positive predictive value were low for all parameters. Lactate in cord arterial blood at birth is at least as good as base deficit to reflect an impaired condition at birth, and best when gestational age-adjusted values are used. Due to methodological confounding involved in calculation of base deficit, lactate may replace base deficit as an acid-base outcome parameter at birth.

A new tool for the validation of umbilical cord acid–base data

To identify the distribution of carbon dioxide tension (pCO(2) ) relative to pH in validated umbilical cord acid-base data. Observational study. European hospital labour wards. Data for 36,432 term newborns were obtained from three sources: two trials of fetal monitoring with electrocardiography (ECG; the Swedish randomised controlled trial and the European Union Fetal ECG trial) and data from Mölndal Hospital. From the total study population, cases with missing values or obvious typing errors were excluded. The remaining data were validated based on specified criteria. Percentiles of arterial pCO(2) by pH were calculated using multilevel regression modelling. Umbilical cord pH, pCO(2) and base deficit. Acid-base values were considered invalid in one out of seven cases. Percentiles for arterial pCO(2) corresponding to specified values of arterial pH were developed from the validated data of 26, 690 cases. Percentiles for arterial pCO(2) for a specified arterial pH can be used as a tool to identify cases with erroneously low pCO(2) values, and thus avoid an incorrect interpretation of the newborn's acid-base status.

Ductus venosus velocimetry in acute fetal acidemia and impending fetal death in a sheep model of increased placental vascular resistance

We investigated whether hypoxemia without acidemia affects ductus venosus (DV) blood velocity waveform pattern in sheep fetuses with intact placenta and whether worsening acidemia and impending fetal death are related to changes in DV velocimetry in fetuses with increased placental vascular resistance. A total of 34 fetuses were instrumented at 115-136/145 days of gestation. Placental embolization was performed in 22 fetuses on the fourth postoperative day, 24 h before the experiment. The control group was comprised of 12 fetuses with intact placenta. The experimental protocol consisted of fetal hypoxemia that was induced by replacing maternal inhaled oxygen with medical air. To further deteriorate fetal oxygenation and blood-gas status, uterine artery volume blood flow was reduced by maternal hypotension. Fetuses that underwent placental embolization were divided into two groups according to fetal outcome. Group 1 consisted of 12 fetuses that completed the experiment, and group 2 comprised 10 fetuses that died during the experiment. DV pulsatility index for veins (PIV) and fetal cardiac outputs (COs) were calculated. Placental volume blood flow, fetal blood pressures, and acid base and lactate values were monitored invasively. On the experimental day, the mean gestational age did not differ significantly between the groups. In groups 1 and 2, the baseline mean DV PIV and fetal COs were not statistically significantly different from the control group. In the control group, the DV PIV values increased significantly with hypoxemia. In groups 1 and 2, the DV PIV values did not change significantly, even with worsening acidemia and imminent fetal death in group 2. During the experiment, the fetal COs remained unchanged. We conclude that fetal hypoxemia increases the pulsatility of DV blood velocity waveform pattern. In fetuses with elevated placental vascular resistance, DV pulsatility does not increase further in the presence of severe and worsening fetal acidemia and impending fetal death.

PREPARATION OF CdIn2Se4n-TYPE SEMICONDUCTOR USED AS THERMOELECTRIC MATERIAL BY SOL–GEL METHOD

The objective of this research was to study the effect of various parameters such as temperature and pH to the formation of cadmium indium selenide ( CdIn2 Se 4 ) thin films, which were fabricated by sol–gel dip-coating method. This n-type semiconductor compound is suitable for application as thermoelectric materials. Cadmium, indium, selenium precursors were separately dissolved by solvents: ethanol, hydrochloric acid, and acetic acid to form metal alkoxides. The precursor solutions were then mixed together in N 2 atmosphere. These metal alkoxides were hydrolyzed by adding water and then polycondensed by adding ethylene glycol to become gels. These gels were adjusted to various acid-base values by adding diethylnolamine. Glass substrates were dipped into the gels to form thin films. These thin films were annealed at various temperatures in N 2 atmosphere and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and fourier transfrom infrared spectroscopy (FTIR) techniques. The results indicated that CdIn2 Se 4 compound occurred by the reaction at room temperature with pH 4 and annealed at 450°C in N 2 atmosphere.

A safe citrate anticoagulation protocol with variable treatment efficacy and excellent control of the acid–base status*

Citrate anticoagulation is an excellent alternative to heparin anticoagulation for critically ill patients requiring continuous renal replacement therapy. In this article, we provide a safe and an easy-to-handle citrate anticoagulation protocol with variable treatment doses and excellent control of the acid-base status. Prospective observational study. University hospital. One hundred sixty-two patients with acute renal failure requiring renal replacement therapy were enrolled in the study. A continuous venovenous hemodialysis-based citrate anticoagulation protocol using a 4% trisodium solution, a specially designed dialysate fluid, and a continuous calcium infusion were used. The study period was 6 days. Hemofilters were changed routinely after 72 hours of treatment. The patients were grouped according to body weight, with patients below 60 kg body weight in group 1, patients with at least 60 kg and up to 90 kg body weight in group 2, and patients with a body weight of above 90 kg in group 3. Dialysate flow was adapted according to body size and matched approximately 2 L/hr for a patient with average body size. Blood flow, citrate flow, and calcium flow were adjusted according to the dialysate flow used. Median filter run time was 61.5 hours (interquartile range: 34.5-81.1 hours). Only 5% of all hemofilters had to be changed because of clotting. The prescribed treatment dose was achieved in all patients. Acid-base and electrolyte control were excellent in all groups. In the rare cases of metabolic disarrangement during citrate anticoagulation, acid-base values were rapidly corrected by modifying either the dialysate flow or alternatively the blood flow rate. Eight patients (5%) developed signs of citrate accumulation indicated by an increase of the total calcium >3 mmol/L or a need for high calcium substitution. We provide a safe and an easy-to-handle citrate anticoagulation protocol that allows an excellent acid-base and electrolyte control in critically ill patients with acute renal failure. The protocol can be adapted to patients' need, allowing a wide spectrum of treatment doses.

Evaluation of Hyperviscous Fluid Resuscitation in a Canine Model of Hemorrhagic Shock: A Randomized, Controlled Study

Enhancing plasma viscosity during fluid resuscitation results in vasodilation and improved microvascular perfusion in rodents subjected to hemorrhagic shock. We hypothesized that resuscitation with hyperviscous lactated Ringer's solution (hyperLRS) would result in improved tissue oxygenation and acid-base values in hemorrhaged dogs. Twelve dogs were anesthetized and splenectomized. Vascular catheterization was performed, and tissue oxygen probes were placed in the jejunal serosa and skeletal muscle to assess macro- and microhemodynamic parameters. Baseline (BL) and posthemorrhage data were obtained. After 1 hour of hemorrhagic shock (mean arterial pressure [MAP] 30-40 mm Hg), treatment groups (n = 6) were administered bolus LRS or hyperLRS, and then received sufficient LRS to achieve and maintain an MAP between 60 mm Hg and 70 mm Hg. Data were obtained at 10, 30, 60, 120, and 180 minutes after fluid resuscitation. There were no significant differences between LRS or hyperLRS groups at BL or posthemorrhage. Blood and plasma viscosity were significantly increased by the administration of hyperLRS at all time points postresuscitation compared with LRS. Significantly more fluid was required to maintain MAP, and vascular hindrance was consistently lower in dogs administered hyperLRS versus LRS, suggesting viscosity-induced vasodilation. Central and mesenteric venous oxygen saturations were significantly decreased, whereas lactate and oxygen extraction ratios were significantly increased after hyperLRS administration compared with LRS. The tissue oxygen tension was similar in dogs administered hyperLRS or LRS. A hyperviscous balanced electrolyte solution did not improve hemodynamic parameters, tissue oxygen tension, or acid-base values despite evidence for viscosity-induced vasodilation.

Blood acid–base and plasma electrolyte values in healthy ostriches: The effect of age and sex

The effect of age and sex on blood acid–base and plasma electrolyte values was determined in venous blood samples from 45 clinically healthy ostriches ( Struthio camelus) from 26 days to 6 years of age. Animals were divided by age into four groups and the group of adults was divided by sex into two subgroups. Blood samples were collected without sedation. There was a significant ( P < 0.05) age difference in blood values of base excess (BE), plasma HCO 3 - , total CO 2 (TCO 2), Na +, K +, Cl − and anion gap (AG). The highest plasma concentrations of Na +, Cl − and value of AG were found in adult ostriches with a steady decrease to chicks. A significant ( P < 0.05) sex difference in adult animals with higher blood pH, lower blood values of pCO 2, BE, plasma concentrations of HCO 3 - , TCO 2 and K + was found in females. We concluded that blood acid–base values and plasma electrolyte concentrations in ostriches are affected by age and sex.

Significance of retrograde diastolic uterine artery blood flow during regional anesthesia in instrumented pregnant sheep

We studied the interactions between uterine and placental hemodynamics during maternal hypotension in chronically instrumented fetal sheep. In addition, we investigated maternal hemodynamic characteristics, fetoplacental hemodynamics and fetal acid-base status when a retrograde diastolic uterine artery blood flow pattern is present during maternal hypotension. Invasive maternal and fetal hemodynamic parameters, uterine (Q(UtA)) and placental (Q(UA)) volume blood flows and acid-base values were examined in 24 chronically instrumented sheep at baseline and during epidural-induced maternal hypotension at 117-132 (term 145) days of gestation. Uterine artery blood flow velocity waveforms were obtained by Doppler ultrasonography. Maternal hypotension decreased Q(UtA) without affecting Q(UA). During hypotension, eight out of 24 sheep demonstrated a retrograde diastolic blood flow velocity waveform pattern in the uterine artery. Maternal systolic, diastolic and mean arterial blood pressures were significantly lower in the retrograde group than in the antegrade group. No statistically significant differences in Q(UtA), Q(UA) and fetal blood gas values were detected between the two groups during hypotension. An acute decrease in uterine artery volume blood flow during maternal hypotension is not compensated by increased placental volume blood flow. A retrograde diastolic blood flow pattern in the uterine artery is related to lower maternal arterial pressures, especially during diastole. A uterine artery retrograde diastolic blood flow pattern does not have any additional detrimental short-term effects on fetal acid-base status.

Bicarbonate buffered ultrafiltration leads to a physiologic priming solution in pediatric cardiac surgery

Pediatric cardiopulmonary bypass (CPB) involves a high ratio of priming blood volume to patient blood volume. The composition of packed red blood cells (RBCs) is very unphysiological in terms of acid-base, electrolyte and metabolite values. Therefore, we tested the hypothesis whether ultrafiltration of the prime and replacement with bicarbonate buffered hemofiltration solution (BB-HS) is sufficient for reducing the metabolic load and reaching a physiologic state. For planned surgery of congenital heart defects with cardiopulmonary bypass, 20 CPB circuits were primed with BB-HS, gelatin and 1 unit of RBCs. The fluid was hemofiltrated using an ultrahemofilter at 300 ml/min until approximately 1000 ml of ultrafiltrate was restored with BB-HS. Blood gas analyses were obtained from the priming blood, once before and once after bicarbonate buffered ultrafiltration (BBUF). The measured substrates decreased significantly (P<0.001) after BBUF (glucose from 13.0+/-2.6 to 6.3+/-1.0 and lactate from 3.8+/-1.5 to 2.3+/-1.0 mmol/l). Acid-base parameters increased (P<0.001) to normal or high normal values (pH from 7.01+/-0.09 to 7.68+/-0.12; HCO(3) from 12.1+/-2.4 to 25.4+/-3.6 mmol/l and BE from -15.4+/-3.6 to -0.8+/-3.7 mmol/l). Even the electrolytes sodium, potassium and calcium changed significantly (P<0.001) toward the physiologic range. BBUF is an efficient method of reducing the metabolic load of priming. After BBUF, even the electrolyte and acid-base balance reached a physiologic state, which is important for minimizing electrolyte and acid-base disturbances after initiation of CPB.

Blood-Gas and Acid–Base Parameters in Nontranquilized Arabian Oryx (Oryx leucoryx) in the United Arab Emirates

Arterial and venous blood-gas and acid-base values were established from a herd (n = 19; 14 male, 5 female) of semi-free-ranging Arabian oryx (Oryx leucoryx) in the United Arab Emirates. The animals were restrained with the use of a modified raceway incorporating a commercially available handling crate. Statistically significant differences were found between arterial and venous values for PO2 (p < 0.001), PCO2 (p = 0.0141), SO2 (p < 0.001), pH (p = 0.0494), and glucose (p < 0.0001). The results are similar to those reported for the same species under field anesthetic conditions, and to those reported from other species of wild bovidae, both tranquilized and nontranquilized, established under similar methods of restraint. In addition, Bland and Altman plots suggest adequate levels of clinical agreement between venous and arterial pH but not between arterial and venous PCO2.

Fetal acid–base balance after betamethasone administration: relation to fetal heart rate variability

To explore whether the known decrease in fetal heart rate variability, which follows antenatal betamethasone administration is related to fetal acid-base changes. A retrospective study of 42 women with premature delivery following a single course of betamethasone. The study group consisted of 21 women who delivered within 48 h following first injection of betamethasone. The 21 women who delivered later than 48 h formed the control group. Fetal heart rate variability measurements and cord acid-base values were compared. The mean fetal heart rate variability (beats per minute) before the administration of betamethasone was significantly higher than at 24 h [8.05 (SD 3.15) vs. 5.32 (SD 2.27); p<0.001]. This was evident in both the groups, with no significant difference between them. In the control group, the mean variability before betamethasone administration and the variability prior to delivery were not significantly different [8.48 (SD 3.46) vs. 7.26 (SD 3.03); p=0.36]. There were no significant differences between study and control groups regarding the arterial cord acid-base values at delivery [pH 7.29 (SD 0.15) vs. 7.31 (SD 0.1); p=0.38]. Assuming that the fetal heart rate and the acid-base status prior to delivery would be a reflection of the effects of betamethasone as evident by reduced fetal heart rate variability, our data does not support acid-base changes as a pathophysiological mechanism.