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Background: Neonatal umbilical artery blood-gas analysis is a diagnostic procedure performed shortly after birth to assess the acid-base balance, oxygenation, and metabolic status of a newborn infant. This retrospective study aimed to investigate the association of prenatal maternal fever with neonatal umbilical artery blood-gas analysis. Methods: A retrospective analysis was conducted on data from 333 parturients and their newborns. Demographic characteristics, clinical information, and neonatal umbilical artery blood gas analysis data were analyzed to evaluate the association between prenatal maternal fever and neonatal blood-gas analysis. Pregnant women with fever (≥38.0 °C) during labor were compared with those without fever. Neonatal umbilical artery blood gas parameters were assessed in relation to the degree and duration of maternal fever. Results: The incidence of the adverse delivery outcome of parturients with high prenatal fever and long duration of fever was significantly higher than that of the low fever, short-term fever, and normal parturients (p < 0.05). The pH of neonatal umbilical veins in the high fever groups was reduced compared with the control group (p < 0.05). Lactic acid (Lac) of neonatal umbilical vein in the low fever and high fever groups was enhanced compared with the control group (p < 0.05). The pH of neonatal umbilical veins in the short-term fever and long-term fever groups was elevated compared with the control group (p < 0.05). The umbilical artery pH and base excess (BE) were positively correlated with maternal peak fever temperature (r = 0.20, r = 0.22, p < 0.05). The umbilical Lac was negatively correlated with maternal peak fever temperature (r = –0.22, p < 0.05). Moreover, the umbilical artery pH and BE were positively correlated with maternal duration of fever (r = 0.29, r = 0.21, p < 0.05). The umbilical artery Lac was negatively correlated with maternal duration of fever (r = –0.25, p < 0.05). Conclusions: The findings suggested that maternal fever during labor was associated with alterations in neonatal umbilical artery blood gas analysis. Understanding the influence of prenatal fever on delivery outcomes is crucial for optimizing maternal and neonatal health.

Non-carbonic buffer power (ßNC) of blood is a pivotal concept in acid-base physiology as it is employed in several acid-base evaluation techniques, including the Davenport nomogram and the Van Slyke equation used for Base excess estimation in blood. So far, ßNC has been assumed to be independent of metabolic acid-base status of blood, despite theoretical rationale for the contrary. In the current study, we used CO2 tonometry to assess ßNC in blood samples from 10 healthy volunteers, simultaneously analyzing the electrolyte shifts across the red blood cellmembrane as these shifts translate the action of intracellular non-carbonic buffers to plasma. The ßNC of the blood was re-evaluated after experimental induction of metabolic acidosis obtained by adding a moderate or high amount of either hydrochloric or lactic acid to the samples. Moreover, the impact of ßNC and pCO2 on the Base excess of blood was examined. In the control samples, ßNC was 28.0 ± 2.5 mmol/L. In contrast to the traditional assumptions, our data showed that ßNC rose by 0.36mmol/L for each 1 mEq/l reduction in plasma strong ion difference (p < 0.0001) and was independent of the acid used. This could serve as a protective mechanism that increases the resilience of blood to the combination of metabolic and respiratory acidosis. Sodium and chloride were the only electrolytes whose plasma concentration changed relevantly during CO2 titration. Although no significant difference was found between the electrolyte shifts in the two types of acidosis, we observed a slightly higher rate of chloride change in hyperchloremic acidosis, while the variation of sodium wasmore pronounced in lactic acidosis. Lastly, we found that the rise of ßNC in metabolic acidosis did not induce a clinically relevant bias in the calculation of Base excess of blood and confirmed that the Base excess of blood was little affected by a wide range of pCO2. [ABSTRACT FROM AUTHOR]

Non-carbonic buffer power (βNC) of blood is a pivotal concept in acid-base physiology as it is employed in several acid-base evaluation techniques, including the Davenport nomogram and the Van Slyke equation used for Base excess estimation in blood. So far, βNC has been assumed to be independent of metabolic acid-base status of blood, despite theoretical rationale for the contrary. In the current study, we used CO2 tonometry to assess βNC in blood samples from 10 healthy volunteers, simultaneously analyzing the electrolyte shifts across the red blood cell membrane as these shifts translate the action of intracellular non-carbonic buffers to plasma. The βNC of the blood was re-evaluated after experimental induction of metabolic acidosis obtained by adding a moderate or high amount of either hydrochloric or lactic acid to the samples. Moreover, the impact of βNC and pCO2 on the Base excess of blood was examined. In the control samples, βNC was 28.0 ± 2.5 mmol/L. In contrast to the traditional assumptions, our data showed that βNC rose by 0.36 mmol/L for each 1 mEq/l reduction in plasma strong ion difference (p < 0.0001) and was independent of the acid used. This could serve as a protective mechanism that increases the resilience of blood to the combination of metabolic and respiratory acidosis. Sodium and chloride were the only electrolytes whose plasma concentration changed relevantly during CO2 titration. Although no significant difference was found between the electrolyte shifts in the two types of acidosis, we observed a slightly higher rate of chloride change in hyperchloremic acidosis, while the variation of sodium was more pronounced in lactic acidosis. Lastly, we found that the rise of βNC in metabolic acidosis did not induce a clinically relevant bias in the calculation of Base excess of blood and confirmed that the Base excess of blood was little affected by a wide range of pCO2.

Introduction: Blood gas analysis (BGA) is an essential test used for years to provide vital information in critically ill patients. However, the instability of the blood gases is a problem. We aimed to evaluate time and temperature effects on blood gas stability. Materials and methods: Arterial blood was collected from 20 patients into syringes. Following BGA for baseline, syringes were divided into groups to stand at 4°C and 22°C for 30, 60, 90, 120 minutes. All were tested for pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), oxygen saturation (sO2), oxyhemoglobin (O2Hb), sodium, potassium, glucose, lactate, oxygen tension at 50% hemoglobin saturation (p50), and bicarbonate. A subgroup analysis was performed to detect the effect of air on results during storage. Percentage deviations were calculated and compared against the preset quality specifications for allowable total error. Results: At 4°C, pO2 was the least stable parameter. At 22°C, pO2 remained stable for 120 min, pH and glucose for 90 min, lactate and pCO2 for 60 min. Glucose and lactate were stable when chilled. Air bubbles interfered pO2 regardless of temperatures, whereas pCO2 increased significantly at 22°C after 30 min, and pH decreased after 90 min. Bicarbonate, sO2, O2Hb, sodium, and potassium were the unaffected parameters. Conclusions: Correct BGA results are essential, and arterial sample is precious. Therefore, if immediate analysis cannot be performed, up to one hour, syringes stored at room temperature will give reliable results when care is taken to minimize air within the blood gas specimen. [ABSTRACT FROM AUTHOR]

Induction of parturition in horses is still not well accepted due to the potential peripartum complications for mares and newborn foals. We assessed differences after spontaneous and induced parturition with low doses of oxytocin (OX) in 1) incidence of peripartum complications in mares; 2) viability, behavioral, physical, and venous blood gas analyses in foals. In this study 61 mares were included; 45/61 were enrolled in the spontaneous foaling group (SF) and 16/61 in the induced foaling group (IF). In the IF group, when the calcium in mammary secretion reached concentrations of ≥250 ppm, mares received a single injection of 2.5 IU of oxytocin IV once a day until foaling. Mares' breed, age, parity, gestational and stage II length, and peripartum complications were recorded. Foal maturity, vital (Apgar score), behavioral and physical parameters were assessed at birth, and the foal clinical condition was monitored for one week. A jugular venous blood sample was collected at birth for blood gas analysis, acid-base status, and lactate assessment. The median gestational length was within the reference interval in all the mares included and did not differ between the two groups. No statistical differences in the II stage length nor in incidence of peripartum complications were observed between the two groups. All the foals were born alive and showed no signs of prematurity/dysmaturity. No statistical differences were found in foal viability between the two groups. Time to stand and nurse from the mare, and body temperature were significantly higher in the IF compared to the SF group. Venous blood pH, SO 2 % and BE were lower, while pCO 2 and lactate were higher in the IF than in the SF group. All the foals in both groups remained clinically healthy during the observation period. In conclusion, at term induction of parturition with a low dose of oxytocin does not have adverse effects on peripartum in mares. Our findings suggest that at term induced foals suffer slightly greater, but not clinically significant, hypoxia, hypercapnia and acidosis than spontaneously delivered foals. • Induction of delivery by a low dose of OX does not adversely affect peripartum in mares at term. • At term induction by a low dose of OX did not impair clinical status of the newborns. • Induced foals showed slightly longer time to stand and suck signs vs. spontaneously delivered. • Induced foals suffered greater hypercapnia and acidosis than spontaneously delivered foals. • In foals no clinical signs were present at birth and during the first week of life. [ABSTRACT FROM AUTHOR]

To establish reference intervals for arterial blood-gas (ABG), acid-base and electrolyte values from a healthy equine population. Retrospective clinical study. A total of 139 client-owned, systemically healthy horses, 1 year of age and older, presented for elective surgical procedures. Blood samples were collected anaerobically from the transverse facial or common carotid artery of horses breathing room air, prior to administration of preanaesthetic medication. Samples were analysed immediately, without correction for body temperature, using an automated bench-top analyser. Variables analysed included pH, arterial partial pressure of carbon dioxide (PaCO 2) and arterial partial pressure of oxygen (PaO 2) and plasma concentrations of sodium (Na+), potassium (K+), calcium (Ca2+) and chloride (Cl−). Actual and standardized plasma bicarbonate concentration [HCO 3 − (P) and HCO 3 − (P, st)], blood and extracellular fluid base excess [base (B) and base (ECF)] and anion gap (AG) were calculated by the machine from preprogrammed algorithms. Methods used for determination of PaCO 2 , PaO 2 , HCO 3 − (P), HCO 3 − (P, st), base (B) and base (ECF) met the guidelines of the Clinical and Laboratory Standards Institute. Reference intervals were determined with the nonparametric or the standard parametric method dependent on data distribution. Reference intervals were determined for pH, 7.37–7.49; PaCO 2 , 4.84–7.20 kPa (36.3–54.0 mmHg); PaO 2 , 11.01–14.97 kPa (82.6–112.3 mmHg); Na+, 133–141 mmol L–1; K+, 3.05–4.65 mmol L–1; Ca2+, 1.34–1.72 mmol L–1; Cl−, 100–110 mmol L–1; HCO 3 − (P), 23.55–33.90 mmol L–1; HCO 3 − (P, st), 23.87–32.45 mmol L–1; base (B), 0.51–8.80 mmol L–1; base (ECF), –0.53 to 9.39 mmol L–1 and AG, 1.5–11.5 mEq L–1. These data were derived from the largest group of horses reported in a single study and may aid in interpretation of ABG, acid-base and electrolyte measurements in clinical practice. [ABSTRACT FROM AUTHOR]

The golden standard method to obtain accurate blood oxygen saturation is blood gas analysis that needs invasive procedure of blood sampling. Photoacoustic technique enables us to measure real-time blood oxygen saturation without invasive procedure. The aim of this study is to use the photoacoustic technique, an optical method, for accurately determining oxygen saturation in vivo. We measured induced photoacoustic signals of arterial blood in the rabbit model of stable hypoxemia after irradiation at 750 and 800 nm. Oxygen saturation was calculated from the photoacoustic signals using two calibration curves. Calibration curve 1 is a conventional curve derived from the absorbance coefficient of hemoglobin, whereas calibration curve 2 is derived from the photoacoustic signals obtained from the original blood vessel model. Simultaneously, blood-gas analysis was performed to obtain the reference standard of oxygen saturation. Regression analysis and Bland-Altman analysis were performed to assess the accuracy of oxygen saturation obtained using the two methods. The oxygen saturation calculated using calibration curves 1 and 2 showed strong correlations with the reference standard in regression analysis (R = 0.965, 0.964, respectively). The Bland-Altman analysis revealed better agreement and precision with calibration curve 2, whereas there was significant underestimation of values obtained using calibration curve 1. Photoacoustic measurement of oxygen saturation using calibration curve 2 provided an accurate estimate of oxygen saturation, which was similar to that obtained using a portable blood-gas analyzer. [ABSTRACT FROM AUTHOR]

The present experiment was designed to study progressive changes in the physiological responses of broiler chickens (Gallus gallus) exposed to different durations of acute heat stress. Male broiler chickens (n=8) at 16 days of age, were exposed to acute heat stress of 34°C for 6, 12 or 18h while control chickens were kept at 25°C. Exposure to different durations of heat stress resulted in significant decreases in the levels of blood HCO3- and pCO2, while pH and pO2 were not changed. Hemoglobin, hematocrit and Na+ values were reduced after 6h while no such change was observed after 12 or 18h of heat stress. In contrast, K+ levels were lowered by 6 or 12h of heat stress and no differences in blood calcium levels were observed between the control and heat-stressed groups. In conclusion, there is evidence that exposure of broiler chickens to different durations of acute heat stress resulted in distinct time-dependent physiological responses. Data set from this experimental model could provide an overview of physiological state in the typical acute heat-stressed birds.

Background: The aim of the study was to retrospectively investigate whether parameters of routine point-of-care testing (POCT) predict hospital mortality in critically ill surgical patients on admission to the intensive care unit (ICU). Methods: Arterial blood analyses of 1551 patients on admission to the adult surgical ICU of the Technical University Munich were reviewed. POCT was performed on a blood gas analyser. The association between acid-base status and mortality was evaluated. Metabolic acidosis was defined by base excess (BE) <-2 mmol/L and, wherever applicable, subdivided into lactic acidosis by lactate >50% of BE, anion gap (AG)-acidosis by AG >16 mmol/L, hyperchloraemic acidosis by chloride >115 mmol/L. Metabolic alkalosis was defined by BE ≥3 mmol/L. Logistic regression analysis identified variables independently associated with mortality. Results: Overall mortality was 8.8%. Mortality was greater in male patients (p=0.012). Mean age was greater in non-survivors (p<0.0005). Nine hundred and eighty-six patients showed no metabolic acid-base disorder (mortality 7.3%), thereof 26 patients with pCO2 >55 mm Hg (mortality 23.1%). Three hundred and seventy-seven patients presented with acidosis (mortality 11.4%), thereof 163 patients with lactic acidosis (mortality 19%). Mortality for alkalosis (174 patients) was 12.1%. Mean blood glucose level for non-survivors was higher compared to survivors (p<0.0005). Logistic regression analysis identified lactate, glucose, age, male gender as independent predictors of mortality. Conclusions: Lactate and glucose on ICU admission independently predict mortality. BE and AG failed as prognostic markers. Lactic acidosis showed a high mortality rate implying that lactate levels should be obtained on ICU admission. Prevalence of hyperchloraemic acidosis was low. Metabolic alkalosis was associated with an increased mortality. Further studies on this disturbance and its attendant high mortality are warranted. [ABSTRACT FROM AUTHOR]

Objective– To evaluate the effect of body position on the arterial partial pressures of oxygen and carbon dioxide (PaO2, PaCO2), and the efficiency of pulmonary oxygen uptake as estimated by alveolar-arterial oxygen difference (A-a difference). Design– Prospective, randomized, crossover study. Setting– University teaching hospital, intensive care unit. Animals– Twenty-one spontaneously breathing, conscious, canine patients with arterial catheters placed as part of their management strategy. Interventions– Patients were placed randomly into lateral or sternal recumbency. PaO2 and PaCO2 were measured after 15 minutes in this position. Patients were then repositioned into the opposite position and after 15 minutes the parameters were remeasured. Measurements and Main Results– Results presented as median (interquartile range). PaO2 was significantly higher ( P=0.001) when patients were positioned in sternal, 91.2 mm Hg (86.0–96.1 mm Hg), compared with lateral recumbency, 86.4 mm Hg (73.9–90.9 mm Hg). The median change was 5.4 mm Hg (1.1–17.9 mm Hg). All 7 dogs with a PaO2<80 mm Hg in lateral recumbency had improved arterial oxygenation in sternal recumbency, median increase 17.4 mm Hg with a range of 3.8–29.7 mm Hg. PaCO2 levels when patients were in sternal recumbency, 30.5 mm Hg (27.3–32.7 mm Hg) were not significantly different from those in lateral recumbency, 32.2 mm Hg (28.3–36.0 mm Hg) ( P=0.07). The median change was −1.9 mm Hg (−3.6–0.77 mm Hg). A-a differences were significantly lower ( P=0.005) when patients were positioned in sternal recumbency, 21.7 mm Hg (17.3–27.7 mm Hg), compared with lateral recumbency, 24.6 mm Hg (20.4–36.3 mm Hg). The median change was −3.1 mm Hg (−14.6–0.9 mm Hg). Conclusions– PaO2 was significantly higher when animals were positioned in sternal recumbency compared with lateral recumbency, predominantly due to improved pulmonary oxygen uptake (decreased A-a difference) rather than increased alveolar ventilation (decreased PaCO2). Patients with hypoxemia (defined as PaO2<80 mm Hg) in lateral recumbency may benefit from being placed in sternal recumbency. Sternal recumbency is recommended to improve oxygenation in hypoxemic patients. [ABSTRACT FROM AUTHOR]

Abstract: Acid–base balance describes the complex processes that work to maintain a stable extracellular pH for optimal cellular function. The process of balancing the production and neutralization of tissue acid provides a great challenge for newborn infants who have significantly higher rates of acid production than adults. Factors which help maintain a stable acid–base balance include buffers, the respiratory system and renal system. Both intracellular and extracellular buffers resist changes in pH; the most important extracellular buffer system for maintaining stable pH is the bicarbonate system. In response to acidosis or alkalosis the respiratory system balances the production of acid with the clearance of CO2 by altering respiratory rate. The kidneys provide a delayed but sustained response to pH imbalance by excreting either acidic or alkaline urine in response to systemic acidosis and alkalosis, respectively. In sick premature infants these systems have a limited capacity completely to control pH. This review discusses the physiology of the three systems which control acid–base balance. Patterns of clinical abnormalities in acid–base status and their underlying causes are discussed. We present a systematic approach to blood gas analysis and interpretation in newborn infants. [Copyright &y& Elsevier]

The pattern of several blood-gas indices has been investigated in eight show jumpers during a 2-day showjumping event. The effectiveness of the athlete horse’s physiological buffering systems has been pointed out, as well as the similarity between the patterns of the indices regarding the acid-base status and those metabolically defining the horse’s physical potential. The results of this study draw attention to the importance of a qualitative and quantitative determination of the blood-gas parameters in the show jumper, not only to define the horse’s acid-base status but also to analyse the potential performance more accurately. [ABSTRACT FROM AUTHOR]

Respiratory function and hemodynamics were studied during laparoscopic cholecystectomy (LC) under a 10 mmHg pneumoperitoneum (PP) by carbon dioxide insufflation. Blood-gas analysis and measurement of cardiac function by using a Swan-Ganz catheter were performed. Creatinine clearance rate was measured preoperatively and intraoperatively. Compared with values obtained before the institution of PP, blood-gas analysis showed a significant increase in PCO2 (P < 0.01), and a significant decrease in pH (P < 0.01) and base excess (P < 0.05) during PP. With respect to cardiac function, there was no significant change in cardiac output, pulmonary arterial pressure, and pulmonary arterial wedge pressure. Intraoperative creatinine clearance rate (Ccr) was decreased in 29 of 48 cases, increased in 18 cases, and unchanged in 1 case, resulting in no significant difference overall between the values measured preoperatively and intraoperatively. However, in eight individual cases, the Ccr was found to have decreased significantly. Although alterations in respiratory function were observed, LC at 10 mmHg PP did not cause any crucial problems in respiratory or cardiac function. It should be kept in mind, however, that renal blood flow may decrease in some cases even at intraabdominal pressures under 10 mmHg. [ABSTRACT FROM AUTHOR]

Objectives To assess acid-base metabolism after bladder substitution with the ileal Kock reservoir, using capillary blood-gas analysis, measurement of the renal excretion of ammonium and titratable acid and the evaluation of renal function by plasma clearance of 51Cr-labelled ethylenediamine tetra-acetic acid (51Cr-EDTA). Patients, subjects and methods The investigation comprised both a cross-sectional study, with initial measurements after surgery, and a longitudinal study, with pre-operative measurements, both groups of patients being followed for 2 years after inclusion. The cross-sectional study included 26 patients (median age 66 years, range 44-75), with a median post-operative follow-up of 1.2 years (range 0.3-3.7), and 16 control subjects (median age 62 years, range 34-80), and the longitudinal study comprised seven patients (median age 57 years, range 42-68). Results The median values for capillary blood pH, carbon dioxide pressure, standard bicarbonate and standard base excess were significantly lower in patients with a bladder substitute than in the control subjects. An acid-base chart showed that the values for 44% of patients and none of the controls were within the area representing mild metabolic acidosis. This difference could not be attributed to differences in renal function because the 51Cr-EDTA clearance was normal and similar in the two groups of patients and among patients and controls. Nevertheless, the median values for each of the variables measured by blood-gas analysis were within the reference interval of the normal population. Net acid excretion was similar in patients with a bladder substitute and control subjects, but urinary pH was significantly higher in the patients. Accordingly, the renal excretion of ammonium was significantly higher and the excretion of titratable acid significantly lower in patients after ileal bladder substitution. Conclusions The results are consistent with the hypothesis that bladder substitution with the ileal Koch reservoir results in an acid load to the body, caused mainly by ammonium reabsorption in the reservoir. The acid load is compensated by an increased renal excretion of ammonium but causes a mild metabolic acidosis in about half the patients. [ABSTRACT FROM AUTHOR]