Blood Acid-base Balance Research Articles

A new analysis of hypoxia tolerance in fishes using a database of critical oxygen level (P crit).

Hypoxia is a common occurrence in aquatic habitats, and it is becoming an increasingly frequent and widespread environmental perturbation, primarily as the result of anthropogenic nutrient enrichment and climate change. An in-depth understanding of the hypoxia tolerance of fishes, and how this varies among individuals and species, is required to make accurate predictions of future ecological impacts and to provide better information for conservation and fisheries management. The critical oxygen level (P crit) has been widely used as a quantifiable trait of hypoxia tolerance. It is defined as the oxygen level below which the animal can no longer maintain a stable rate of oxygen uptake (oxyregulate) and uptake becomes dependent on ambient oxygen availability (the animal transitions to oxyconforming). A comprehensive database of P crit values, comprising 331 measurements from 96 published studies, covering 151 fish species from 58 families, provides the most extensive and up-to-date analysis of hypoxia tolerance in teleosts. Methodologies for determining P crit are critically examined to evaluate its usefulness as an indicator of hypoxia tolerance in fishes. Various abiotic and biotic factors that interact with hypoxia are analysed for their effect on P crit, including temperature, CO2, acidification, toxic metals and feeding. Salinity, temperature, body mass and routine metabolic rate were strongly correlated with P crit; 20% of variation in the P crit data set was explained by these four variables. An important methodological issue not previously considered is the inconsistent increase in partial pressure of CO2 within a closed respirometer during the measurement of P crit. Modelling suggests that the final partial pressure of CO2 reached can vary from 650 to 3500 µatm depending on the ambient pH and salinity, with potentially major effects on blood acid-base balance and P crit itself. This database will form part of a widely accessible repository of physiological trait data that will serve as a resource to facilitate future studies of fish ecology, conservation and management.

FEATURES OF EARLY NEONATAL ADAPTATION IN INFANTS BORN TO MOTHERS WITH HYPERTENSIVE DISORDERS OF PREGNANCY

To assess the clinical and laboratory characteristics of an adaptation period in babies delivered by cesarean section in hypertensive women, a survey was conducted in 196 neonatal infants. Fetal growth restriction, Apgar scores, degree of asphyxia, and resuscitation needs were determined. Umbilical cord indicators, such as blood gas composition and acid-base balance in the umbilical artery and vein, were studied. The course of an early postnatal adaptation and the outcomes of an early neonatal period were analyzed. The newborn babies of hypertensive mothers were found to have lower gestational age at birth, lower weight and height, a higher incidence of fetal growth restriction, and failure of most organs and systems, which considerably hampered their postnatal adaptation. In the group of babies born to mothers with severe preeclampsia, impairment in early neonatal adaptation processes was more pronounced than in those of mothers with chronic hypertension.

Blood Coagulation and Acid-Base Balance at Craniocerebral Hypothermia in Patients with Severe Traumatic Brain Injury

Systemic therapeutic hypothermia has gained a negative reputation in treating multiple trauma patients and is regarded as one of the factors in the lethal triad of shock, acidosis, and hypothermia. This fact owes to no relationship between acidosis and hypothermia; the effects of the latter on coagulation are evident and complexly reversible in the presence of acidosis. Objective: to determine the impact of noninvasive local brain cooling on the metabolic and blood coagulation indicators of a patient with acute cerebral ischemia. Subjects and methods. The subjects of the study were 113 patients with severe brain injury, including that complicated by the involvement of stem structures, who underwent brain cooling in different modifications. In so doing, the val ues of acidbase balance and coagulation system in arterial and venous blood were investigated. Results. Local brain hypother mia was not found to affect coagulation while the baseline negative values of excess buffer bases showed positive values (a right shift) by the end of cooling. Recommendations were given to prevent metabolic shifts. Conclusion. Patients at very high risk for bleeding may be safely cooled to a brain temperature of 32—34°C even in the presence of moderatetosevere acidosis. This is a great advantage of local hypothermia over systemic one.

Dry period cooling ameliorates physiological variables and blood acid base balance, improving milk production in murrah buffaloes.

This study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subsequent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly (P<0.05) lower in group 2, with the provision of cooling. Skin surface temperature at thorax was significantly lower in cooled group relative to noncooled group. Blood pH and pO2 were significantly (P<0.05) higher in heat stressed group as compared to the cooled group. pCO2, TCO2, HCO3, SBC, base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly (P<0.05) higher in cooled group as compared to noncooled group. DMI was significantly (P<0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher (P<0.05) in cooled group of Murrah buffaloes.

Correction of Poikylocytosis and Blood Biochemical Indicators in Acute Blood Loss

Objective: to provide a rationale for the use of perfluorane to correct erythrocyte morphological changes and blood biochemical indicators in acute blood loss. Material and methods. Experiments were carried out in outbred male rats weighing 250—300 g under nembutal anesthesia. Blood loss was induced by arterial blood exfusion until blood pressure (BP) reached 40 mm Hg, following which this BP level was maintained for 60 minutes. Then the amount of blood withdrawn was reinfused. Perfluorane was injected intraarterially at a dose of 3 ml/kg 45 min before the start of blood loss. On the following day arterial and venous blood samples were harvested. The values of metabolic parameters (acid-base balance (ABB), hemoglobin (Hb), packed cell volume (PCV), and blood biochemistry), the morphological characteristics of erythrocytes (the size of discocytes and the percentage of stomatocytes and echinocytes), and the levels of reticulocytes in peripheral blood were studied. Results. Perfluorane exerted a normalizing effect on the values of blood ABB. Twenty-four hours after blood loss and reinfusion, Group 1 (a non-perfluorane group; n=8) showed reductions in Hb, PCV, and serum iron as compared to Group 3 (intact animals; n=12). In Group 2 (a perfluorane group; n=10), these indicators were decreased to a lesser extent. In these time periods, hypercholesterolemia was less marked in Group 2 than in Group 1. In Group 2, the mean diameter of a discocyte was larger than that in the animals of the two other groups. Group 1 displayed as high as 32% increases in the count of echinocytes with their virtually complete absence in the intact animals. At the same time, the levels of echinocytes in Group 2 animals were similar to those in the intact animals. As compared to Group 3, Group 1 exhibited a 4.5-fold drop in the percentage of reticulocytes (р≤0.05) while Group 2 showed a 2.2-fold rise in this indicator (р≤0.05). Conclusion. The injection of perfluorane at a dose of 3 ml/kg body weight 45 min prior to blood loss causes an increase in the values of Hb, PCV, and serum iron and a reduction in total cholesterol. The administration of perfluorane

Порівняльна оцінка терапевтичної дії різних інфузійних розчинів на показники кислотно-лужної рівноваги крові щурів з гострою церебральною ішемією

Порівняльна оцінка терапевтичної дії різних інфузійних розчинів на показники кислотно-лужної рівноваги крові щурів з гострою церебральною ішемією

Effect of dietary cation-anion difference on performance of lactating dairy cows and stability of milk proteins

Casein micelle stability is negatively correlated with milk concentrations of ionic calcium, which may change according to the metabolic and nutritional status of dairy cows. The present study aimed to evaluate the effect of dietary cation-anion difference (DCAD) on concentrations of casein subunits, whey proteins, ionic calcium, and milk heat and ethanol stability. Sixteen Holstein cows were distributed in 4 contemporary 4×4 Latin square designs, which consisted of 4 periods of 21d and 4 treatments according to DCAD: 290, 192, 98, and −71mEq/kg of dry matter (DM). The milk concentrations of ionic calcium and κ-casein were reduced as DCAD increased, whereas the milk urea nitrogen and β-lactoglobulin concentrations were increased. As a result of these alterations, the milk ethanol stability and milk stability during heating at 140°C were increased linearly with increasing DCAD [Y=74.87 (standard error=0.87) + 0.01174 (standard error=0.0025) × DCAD (mEq/kg of DM) and Y=3.95 (standard error=1.02) + 0.01234 (standard error=0.0032) × DCAD (mEq/kg of DM), respectively]. In addition, 3.5% fat-corrected milk and fat, lactose, and total milk solids contents were linearly increased by 13.52, 8.78, 2.5, and 2.6%, respectively, according to DCAD increases from −71 to 290mEq/kg of DM, whereas crude protein and casein content were linearly reduced by 4.83 and 4.49%, respectively. In conclusion, control of metabolic changes in lactating dairy cows to maintain blood acid-base equilibrium plays an important role in keeping milk stable to ethanol and during heat treatments.

23 NEONATAL SUPPORT THERAPY AND BLOOD GAS EVALUATION IN CLONED AND ARTIFICIAL INSEMINATION-DERIVED NEWBORN CALVES

Offspring derived from artificial reproductive techniques are already known to present several postnatal undesirable phenotypes and clinical disorders. Despite its benefits, cloning by somatic cell nuclear transfer (SCNT) is extremely inefficient. The birth rate in cattle is around 5% of the transferred blastocysts, and ~50% of delivered calves die in the first 48 h. Neonatal respiratory distress is reported to be one of the main causes of such deaths. Veterinary intervention is often needed to promote or improve blood oxygenation, avoiding respiratory acidosis and improving carbon dioxide delivery from blood/lungs to the environment. This study aimed to evaluate a neonatal support therapy over the blood gas and acid-base balance on newborn calves derived from SCNT or AI. Four cloned and 3 AI-derived calves delivered by Caesarean section were used for the experiment. Postnatal therapeutic procedures were comprised 4 doses of 400 mg of intratracheal surfactant every 15 min, 25 mg of oral sildenafil every 8 h for 3 days, and 5 L min–1 intranasal oxygen. Blood collections were performed within 30 min (T0), at 12 (T12), 24 (T24) and 48 (T48) hours after delivery. Blood samples were collected from the caudal auricular artery with a butterfly and a blood gas syringe. Oxygen saturation (sO2), arterial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), pH, and bicarbonate (HCO3–) were evaluated with a portable blood gas analyzer (i-STAT, Abbott Point of Care Inc., Princeton, NJ, USA). Data obtained were submitted to ANOVA (Proc MIXED; SAS/STAT, version 9; SAS Institute Inc., Cary, NC, USA). There were significant differences between groups in blood pH (P = 0.0182) and between groups (P = 0.0281) and time of collection (P = 0.0303) in blood bicarbonate (HCO3–). The AI calves were born with normal pH (7.468 ± 0.033) and the cloned calves were born in acidosis (7.216 ± 0.166). These calves were stabilised in T48 (7.427 ± 0.017) using their own HCO3– that increased over time. Although there were no differences in sO2 (P = 0.4525), PaO2 (P = 0.3086), or PaCO2 (P = 0.2514), sO2 and PaO2 were numerically increased at the same time that PaCO2 decreased in both groups. In the cloned calves, the sO2, PaO2, and PaCO2 at T0 were 61.3 ± 28.6%, 39.8 ± 18.5 mmHg, and 65.8 ± 29.3 mmHg, respectively and reached 90.0 ± 3.4%, 57.7 ± 15.8 mmHg, and 42.0 ± 3.7 mmHg. In the AI calves, T0 blood gas analysis were 79.8 ± 19.4%, 56.1 ± 42.1 mmHg, and 39.1 ± 4.8 mmHg, and at T48 were 89.0 ± 2.6%, 82.3 ± 43.5 mmHg, and 43.0 ± 4.9 mmHg for sO2, PaO2, and PaCO2 respectively. The neonate support therapy improved calves' oxygenation and helped to eliminate the carbon dioxide from the blood. In our experience, the neonatal treatment was essential in supporting the lives of the cloned calves.Funding support was received from FAPESP 2011/19543–9.

Blood gas analysis, anion gap, and strong ion difference in horses treated with polyethylene glycol balanced solution (PEG 3350) or enteral and parenteral electrolyte solutions

Large volumes of different electrolytes solutions are commonly used for ingesta hydration in horses with large colon impaction, but little is known about their consequences to blood acid-base balance. To evaluate the effects of PEG 3350 or enteral and parenteral electrolyte solutions on the blood gas analysis, anion gap and strong ion difference, five adult female horses were used in a 5x5 latin square design. The animals were divided in five groups and distributed to each of the following treatments: NaCl (0.9% sodium chloride solution); EES (enteral electrolyte solution), EES+LR (EES plus lactated Ringer's solution); PEG (balanced solution with PEG 3350) and PEG+LR (PEG plus lactated Ringer's solution). Treatments PEG or PEG + LR did not change or promoted minimal changes, while the EES caused a slight decrease in pH, but its association with lactated Ringer's solution induced increase in AG and SID values, as well as caused hypernatremia. In turn, the treatment NaCl generated metabolic acidosis. PEG 3350 did not alter the acid-base balance. Despite it's slight acidifying effect, the enteral electrolyte solution (EES) did not cause clinically relevant changes.

Evaluation of acid-base control, electrolyte balance, and filter patency of a Prismaflex-based regional citrate anticoagulation protocol for pre-dilution continuous veno-venous hemodiafiltration.

Regional citrate anticoagulation (RCA) is increasingly used in patients requiring continuous renal replacement therapy (CRRT). This study evaluated a new RCA protocol based on the Prismaflex® dialysis device and an isotonic citrate solution (prismocitrate) for pre-dilution continous veno-venous hemodiafiltration. The Prismaflex®/Prismocitrate-based protocol involved an AN69ST® membrane (Prisma Flex ST100), a blood flow of 120 mL/min, 1.8 L/h Prismocitrate (10 mmol/L citrate/2 mmol/L citric acid) substitution fluid in pre-dilution mode, and 0.8 L/h dialysate flow (PrismOcal) at the start. In parallel, infusions of potassium, calcium, and magnesium were initiated. Blood pH, bicarbonate, base excess, and ionized calcium levels were measured in 6 hours intervals and magnesium levels every 24 hours. Scheduled hemofilter run time was 72 hours. A consecutive series of 25 continuous renal replacement treatments was analyzed in 15 patients. After at least 6h of RRT, 69.9% of bicarbonate concentrations and 84.6% base excess (BE) calculations were below normal range. During CRRT, mean bicarbonate decreased from 22.9 to 20.2 mmol/L and mean BE from -1.5 to -4.2 mmol/L. In addition, 66.3% of ionized systemic calcium concentrations were out of the normal range, while 54.1% of the magnesium readings were above normal range. Five filters reached the scheduled run time of 72 hours, 19 treatments stopped prematurely because of RRT related reasons (5 filter clottings, 2 severe metabolic disarrangements, 12 major Prismaflex® hardware or software handling problems). One patient was switched to intermittent hemodialysis. The evaluated Prismaflex®/ Prismocitrate-based citrate anticoagulation protocol provides insufficient control of blood acid-base and electrolyte balance.

Взаимосвязь интраабдоминального давления с показателями газов крови, кислотно-основного состояния и частотой ИВЛу пациентов с острым деструктивным панкреатитом

Взаимосвязь интраабдоминального давления с показателями газов крови, кислотно-основного состояния и частотой ИВЛу пациентов с острым деструктивным панкреатитом

Studying the influence of some reactive oxygen species on physical and chemical parameters of blood

The aim of this work was to estimate the dynamics of blood physical and chemical parameters when blood specimens were processed by singlet oxygen in vitro. Our experiments were executed with whole blood specimens of healthy people (n=10). Each specimen was divided into five separate portions of 5 ml. The first portion was a control (without any exposures). The second one was processed by an oxygen-ozone mixture (at ozone concentration of 500 mcg/l, the third portion--by oxygen, and the fourth and fifth ones were processed by a gas mixture with singlet oxygen (50 and 100% of generator power). In blood samples after processing we studied the activity of lactate dehydrogenase, aldehyde dehydrogenase and superoxide dismutase, erythrocyte and plasma levels of glucose and lactate, acid-base balance and the partial pressure of gases in blood. It was found out, that blood processing by singlet oxygen leads to optimization of energy, detoxication and antioxidant enzymes functioning with changes in plasma and erythrocyte level of glucose and lactate, normalization of blood gases level and acid-base balance. Our results show, that the effect of singlet oxygen on enzyme activity is more pronounced than exposure to an oxygen-ozone gas mixture.

Acute regulation of hematocrit and acid–base balance in chicken embryos in response to severe intrinsic hypercapnic hypoxia

The regulation of blood acid–base balance and hematology in day 15 chicken embryos in response to partial water submersion (with egg's air cell in air) and complete submersion producing severe intrinsic hypercapnic hypoxia and recovery in air was studied. The acid–base disturbance during submersion was characterized by initial rapid respiratory changes and then superseded by metabolic processes, resulting in a large progressive hysteresis. Throughout submersion and recovery, blood lactate concentration changed swiftly along with the changes in bicarbonate concentration ([HCO3−]), indicating that anaerobic glycolysis determined overall acid–base disturbances. Both partial and complete submersion produced large, rapid increases in hematocrit through proportional increases in mean corpuscular volume and red blood cell concentration. Death ensued once the internal pool of O2 was exhausted and/or the acid–base disturbance became too severe for survival (i.e., [HCO3−]a<∼10mmolL−1). However, embryos recovered from acid–base and hematological disturbances within 120min recovery in air after short bouts of complete (20min) or partial (60min) submersion, suggesting that shorter severe intrinsic hypercapnic hypoxia does not compromise viability of embryos.

Blood acid-base balance of sportsmen during physical activity

The aim of this study was to investigate the acid-base balance parameters in blood of sportsmen by physical activity. Before exercise lactate concentration in blood was normal. Carbon dioxide pressure (рСО2), bicarbonate concentration (НСО3 -), base excess (BE), were increased immediately after physical activity lactate concentration increased, while pH, BE, НСО3 -, рСО2 decreased in capillary blood of sportsmen. These changes show the development of lactate-acidosis which is partly compensated with bicarbonate buffering system and respiratory alkalosis. During postexercise recovery lactate concentration decreased, while рСО2, НСО3 -, BE increased. The results of this study can be used for diagnostics of acid-base disorders and their medical treatment for preservation of sportsmen physical capacity.

Changes in blood acid-base balance parameters and coagulation profile during diarrhea in calves

The purpose of this study was to investigate possible alterations in acid-base balance parameters and the coagulation profile in neonatal diarrheic calves. Twenty neonatal diarrheic and 20 clinically healthy neonatal calves aged between 1 week to 10 days were used. All blood samples were taken on the third day from the onset of diarrhea symptom. Venous blood samples were collected from each animal to determine platelet numbers, pH, pCO2, pO2, HCO(3-), BE, O2SAT, ctCO2 and electrolytes (K+, Na+ and Cl(-)). Plasma samples were collected from each animal for the measurement of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), the concentrations of fibrinogen, D-dimer and the activity of antithrombin III (AT III). Blood pH (7.19), BE (-10.6 mmol/l), HCO3(-) (25.15 mmol/l), pO2 (3.33 kPa), O2SAT (24.12 %) were significantly lower and serum concentration of K+ (6.55 mmol/l) was significantly higher in diarrheic calves. These changes indicate the state of uncompensated metabolic acidosis with accompanying hyperkalemia. TT (32.05s) and APTT (39.9s) values were more prolonged in calves with diarrhea than in the control group. D-dimer (587.25 microg/l) concentrations were significantly increased while a visible drop in AT III (103.75%) activity and platelets counts (598 x10(9)/l) were observed in diarrheic group of calves. The results suggest that a consumptive type of disseminated intravascular coagulation (DIC) developed in diarrheic calves.

Interactive effects of photoperiod and light intensity on blood physiological and biochemical reactions of broilers grown to heavy weights

The effects of photoperiod, light intensity, and their interaction on blood acid-base balance, metabolites, and electrolytes in broiler chickens under environmentally controlled conditions were examined in 2 trials. A 3 × 3 factorial experiment in a randomized complete block design was used in this study. In each trial, all treatment groups were provided 23L:1D with 20 lx of intensity from placement to 7 d, and then subjected to the treatments. The 9 treatments consisted of 3 photoperiods [long/continuous (23L:1D) from d 8 to 56, regular/intermittent (2L:2D), and short/nonintermittent (8L:16D) from d 8 to 48 and 23L:1D from d 49 to 56, respectively] and exposure to 3 light intensities (10, 5.0, and 0.5 lx) from d 8 through d 56 at 50% RH. Feed and water were provided ad libitum. Venous blood samples were collected on d 7, 14, 28, 42, and 56. Main effects indicated that short/nonintermittent photoperiod significantly (P < 0.05) reduced BW, pH, partial pressure of O2, saturated O2, Na(+), K(+), Ca(2+), Cl(-), osmolality, triiodothyronine (T3), and total protein along with significantly (P < 0.05) elevated partial pressure of CO2, hematocrit, hemoglobin, and lactate concentrations. In addition, there were no effects of photoperiod on HCO3(-), glucose, anion gap, and thyroxine (T4). Plasma corticosterone was not affected by photoperiod, light intensity, or their interaction. There was no effect of light intensity on most of the blood variables examined. Acid-base regulation during photoperiod and light intensity exposure did not deteriorate despite a lower pH and higher partial pressure of CO2 with normal HCO3(-). These results indicate that continuous exposure of broiler chickens to varying light intensities had a minor effect on blood physiological variables, whereas the short photoperiod markedly affected most blood physiological variables without inducing physiological stress in broilers.

Causes of Acute Intranatal and Postnatal Hypoxia in Neonatal Infants

Objective: to study the causes of acute intranatal hypoxia and reveal a relationship of placental changes to respiratory failure (RF) in newborn infants. Subjects and methods. The investigation included 252 neonates with the complicated course of an early neonatal period. Their gestational age was 26 weeks to 40 weeks, birth weight varied from 850 g to 4100 g. 95.3% of the newborn infants were born with a low Apgar score and RF, which required mechanical ventilation immediately after birth. The neonatal status was clinically evaluated; the values of blood gas composition and acid-base balance were recorded; the pathogen was discharged from the tracheobronchial tree; chest X-ray survey and placental morphological examination were performed. Results. The main cause of neonatal respiratory failure is chronic intrauterine hypoxia caused by placental inflammatory changes and fetal-placental blood circulatory disorders, which gives rise to preterm delivery, cerebral hemodynamic disorders, and neonatal amniotic fluid aspiration. Bacteriological examination of tracheobronchial aspirations showed that no microflora growth occured in the majority of the newborns acute intranatal hypoxia. Enterococcus faecalis and Staphylococcus epidermidis were isolated in 12.3% and 8.7%, respectively. Growth of в-hemolytic streptococcus was observed in 2.8% of cases. The rate of microbial association specific only for rate premature infants with neonatal respiratory distress syndrome (NRDS) was 4.8%. Conclusion. Placental changes causing fetal-placental circulatory disorders were ascertained to be responsible for acute intranatal and postnatal neonatal hypoxia. Placental inflammatory changes occurred in the majority of cases, as confirmed by bacteriological examinations of neonatal infants. Isolation of the varying microbial flora in infants with RF to a greater extent is, indicative of the infectious process occurring in the maternal body. Key words: acute intranatal hypoxia, neonatal amniotic fluid aspiration, intrauterine infection.

More effective dithiocarbamate derivatives inhibiting carbonic anhydrases, generated by QSAR and computational design

Dithiocarbamates (DTC) are promising compounds with potential applications in antitumoral and glaucoma therapy. Our aim is to understand molecular features affecting DTC interaction with carbonic anhydrases (CAs), zinc-containing enzymes maintaining acid-base balance in blood and other tissues. To this end, we generate QSAR models based on a compound series containing 25 DTC, inhibitors of four human (h) CAs isoforms: hCA I, II, IX and XII. We establish that critical physicochemical parameters for DTC inhibitory activity are: hydrophobic, electronic, steric, topological and shape. The predictive power of our QSAR models is indicated by significant values of statistical coefficients: cross-validated correlation q2 (0.55–0.73), fitted correlation r2 (0.75–0.84) and standard error of prediction (0.47-0.23). Based on the established QSAR equations, we analyse 22 new DTC derivatives and identify DTC dicarboxilic acids derivatives and their esters as potentially improved inhibitors of CA I, II, IX and XII.

Acute regulation of hematocrit and blood acid–base balance during severe hypoxic challenges in late chicken embryos (Gallus gallus)

Acid–base and hematocrit (Hct) responses of vertebrate embryos to severe hypoxia are as yet unknown, but may reveal the maturation process of physiological regulatory mechanisms. The present study elucidated how acute, severe hypoxia (10% O2, with and without 5% CO2) affects Hct and blood acid–base balance in late prenatal (days 11–19) chicken embryos. The time-course of the resulting Hct changes and blood acid–base disturbances was examined in detail in day 15 (d15) embryos to further understand the magnitude and time-components of these physiological changes. We hypothesized that Hct of developing embryos increases during severe hypoxia (10% O2) and hypercapnic hypoxia (5%CO2, 10%O2), due to increased mean corpuscular volume (MCV) and red blood cell concentration ([RBC]). We additionally hypothesized that 10% O2 would induce anaerobic glycolysis and the attendant increase in lactate concentration ([La−]) would create a severe metabolic acidosis. Hct increased in all embryos (d11–d19) during severe hypoxia (2h) but, with the exception of d19 embryos, the increase was due to increased MCV and was therefore unlikely related to O2 transport. The time-course of the d15 embryonic Hct response to hypoxic or hypercapnic hypoxic exposure was very rapid with MCV increasing within 30min. Severe metabolic acidosis occurred in all developing embryos (d11–d19) during 2h hypoxic exposure. Additionally, respiratory acidosis was induced in d15 embryos during hypercapnic hypoxia, with acid–base status recovering within 120min in air. Throughout hypoxic exposure and recovery, changes in [HCO3−] were matched by those in [La−], indicating that anaerobic glycolysis is a key factor determining the metabolic alterations and overall acid–base status. Further, the blood gas and Hct values recovered in air and unchanged embryo mass suggest that the hypoxia-induced disturbances were only transient and may not affect long-term survival.

Cardiopulmonary and analgesic effects of caudal epidurally administered ropivacaine in cattle

ObjectiveTo assess cardiopulmonary and analgesic effects after administration of ropivacaine into the caudal epidural space of cattle. Study designProspective, single-dose trial. AnimalsEight healthy mixed breed cows aged 8 ± 5 years and weighing 507 ± 112 kg. MethodsCaudal epidural anesthesia was produced in cows with 0.75% ropivacaine (0.11 mg kg−1). Onset time, duration and cranial spread of analgesia were recorded. Heart rate (HR), respiratory rate (fR), rectal temperature (RT), and mean arterial blood pressure (MAP) were measured prior to epidural administration (T0) and at 15, 30, 60, 120, 180 and 240 minutes after epidural administration (T15, T30, T60, T120, T180 and T240). Arterial blood acid-base balance (pH, standard bicarbonate and base excess), gas tension (PaO2, PaCO2, SaO2) and electrolytes (Na+, K+, iCa2+,Cl−) were recorded at T0, T30, T60, T120, T180 and T240. Ataxia was evaluated at T0, T30, T60, T120, T180 and T240 and at 1 hour intervals thereafter until analgesia was no longer present in each animal. ResultsEpidurally administered ropivacaine induced variable analgesia extending bilaterally from the coccyx to S3. Time to onset of analgesia and mean duration in the perineal area were 15 ± 4 and 359 ± 90 minutes, respectively. Respiratory rate and RT increased from T120 to T240 when compared to the value at T0. Ionized calcium and chloride concentrations increased at T180 and T240 when compared to T0. The other variables were not significantly different from baseline values (p> 0.05). Four animals were mildly ataxic. Conclusion and clinical relevanceRopivacaine (0.75%, 0.11 mg kg−1) can be administered by caudal epidural injection to produce prolonged bilateral perineal analgesia with minimal ataxia and cardiopulmonary changes in standing cattle.