Actual Base Excess Research Articles

Application of different CO2 pneumoperitoneum pressure in laparoscopic pyeloplasty for infants with ureteropelvic junction obstruction.

Laparoscopic pyeloplasty is a minimally invasive approach for the therapy of infant ureteropelvic junction obstruction (UPJO), reliant on CO2 pneumoperitoneum insufflation. While the impact of CO2 insufflation on adult and older pediatric populations has been studied, its effects on infants remain less explored. This prospective randomized controlled trial included infants with UPJO undergoing laparoscopic pyeloplasty. Patients were allocated to low pneumoperitoneum pressure (LPP, 5 mmHg) or high pneumoperitoneum pressure (HPP, 8 mmHg) groups. Surgical parameters, postoperative complications, acid-base balance, stress markers, inflammatory cytokines, and oxidative stress markers were evaluated and compared. A total of 116 infants were analyzed. Preoperative characteristics were comparable between LPP and HPP groups. No significant differences in blood loss, operation time, or hospitalization time were observed. Postoperative complications were similar between groups. Acid-base balance analysis revealed a decrease in pH after pneumoperitoneum in both groups, with greater reductions in actual base excess and standard base excess in the HPP group. Stress markers, cytokines, and oxidative stress markers increased postoperatively in both groups, with higher levels in the HPP group. HPP leads to more pronounced physiological responses, including acid-base alterations, stress reactions, and inflammatory cytokine elevations.

Clinical analysis of patients with cardiopulmonary resuscitation in emergency department and establishment of prediction model of restoration of spontaneous circulation in hospital

To screen the independent influencing factors of restoration of spontaneous circulation (ROSC) in patients after cardiopulmonary resuscitation (CPR) and establish a predictive model, and explore its clinical value. A retrospective case control study was conducted. The clinical data of cardiac arrest patients admitted to the emergency department of Tangdu Hospital of Air Force Military Medical University and received CPR from January to July 2023 were analyzed, including general information, blood biochemical indicators, main cause of cardiac arrest, whether it was defibrillation rhythm, duration from admission to CPR, and whether ROSC was achieved. The clinical data between the patients whether achieved ROSC or not were compared. The binary multivariate Logistic regression analysis was used to screen the independent influencing factors of ROSC in in-hospital CPR patients. According to the above influencing factors, the ROSC prediction model was established, and the receiver operator characteristic curve (ROC curve) was drawn to evaluate the predictive value of the model for ROSC. A total of 235 patients who received CPR in the emergency department were enrolled, including 153 cases (65.11%) of in-hospital CPR and 82 cases (34.89%) of out-of-hospital CPR. The ROSC ratio was 30.21% (71/235). Among all patients, the majority were aged 61-80 years [40.43% (95/235)], and cardiogenic disease was the main cause of cardiac arrest [32.77% (77/235)]. Among 153 patients with in-hospital CPR, 89 were non-ROSC and 64 were ROSC with ROSC rate of 41.83%. Compared with the non-ROSC group, the patients in the ROSC group had lower blood lactic acid (Lac), N-terminal pro-brain natriuretic peptide (NT-proBNP), Lac/albumin (Alb) ratio (LAR), and ratio of non-defibrillation rhythm [Lac (mmol/L): 5.50 (2.33, 9.65) vs. 7.10 (3.50, 13.35), NT-proBNP (μg/L): 0.87 (0.20, 8.68) vs. 3.00 (0.58, 20.17), LAR: 0.14 (0.07, 0.29) vs. 0.19 (0.10, 0.43), non-defibrillation rhythm ratio: 68.75% (44/64) vs. 93.26% (83/89)], higher actual base excess (ABE) and Alb [ABE (mmol/L): -3.95 (-12.75, 0.23) vs. -7.50 (-13.50, -3.35), Alb (g/L): 38.13±7.03 vs. 34.09±7.81], and shorter duration from admission to CPR [hours: 3.25 (1.00, 14.00) vs. 8.00 (2.00, 27.50)], the differences were statistically significant (all P < 0.05). Binary multivariate Logistic regression analysis showed that LAR [odds ratio (OR) = 0.037, 95% confidence interval (95%CI) was 0.005-0.287], non-defibrillation rhythm (OR = 0.145, 95%CI was 0.049-0.426), and duration from admission to CPR (OR = 0.984, 95%CI was 0.972-0.997) were independent influencing factors for ROSC in hospitalized CPR patients (all P < 0.05). Based on the above influencing factors, a ROSC prediction model was constructed through regression analysis results. The ROC curve analysis showed that the area under the ROC curve (AUC) for predicting ROSC in in-hospital CPR patients was 0.757 (95%CI was 0.680-0.834), Yoden index was 0.429, sensitivity was 76.6%, and specificity was 66.3. LAR, non-defibrillation rhythm and duration from admission to CPR were independent influencing factors for ROSC in patients with in-hospital CPR. The ROSC prediction model established based on the above influencing factors has a good predictive value for ROSC of CPR patients in hospital, and can guide clinicians to evaluate the prognosis of patients through relevant indicators as early as possible.

Effects of time delay and blood storage methods on analysis of canine venous blood samples with an Element point-of-care analyzer.

Manufacturers of point-of-care (POC) analyzers recommend immediate processing and anaerobic collection of blood samples. However, it is not uncommon for clinical scenarios to result in delayed sample processing or room air exposure that could impact the test results. To investigate the effect of time delay and sample storage method on key POC analytes in canine venous blood samples processed with an Element POC analyzer. Blood gas analysis was performed on venous blood samples at times 0 (T0), 15, 30, and 60 minutes after sampling using three different storage methods: preheparinized plastic syringes and two different lithium heparin tubes. To determine clinical relevance, results were compared with allowable total error of the respective parameter. Significance was set at P < 0.05. Significant differences between the three storage methods at baseline were found for partial pressure of carbon dioxide (PCO2 ), partial pressure of oxygen (PO2 ), base excess, and total hemoglobin. No significant differences up to T60 were found within collection methods for actual bicarbonate (HCO3 - ), base excess, sodium, potassium, chloride, ionized calcium (iCa), glucose, and BUN. Significant differences within collection methods were found after T0 for creatinine, after 15 minutes for lactate, and after 30 minutes for pH and hematocrit. No significant differences were found for PO2 in samples stored in preheparinized plastic syringes at any time point. These results suggest that HCO3 - , sodium, potassium, chloride, iCa, glucose, and BUN are comparable within the three storage methods for up to 60 minutes after sampling without resulting in clinically relevant changes.

Promjena acidobazne ravnoteže krvi u lakon ovaca tijekom različitih stadija laktacije

The aim of the present study was to determine the acid-base balance in the blood of the Lacaune sheep during different lactation stages. Thirty lactating Lacaune sheep were involved in the research, and were monitored in the early (day 60), medium (day 120), and late lactation stages (day 180). The following parameters were determined in the blood plasma: pH, partial pressure of carbon dioxide – pCO2, partial pressure of oxygen – pO2, total pressure of carbon dioxide – tCO2, oxygen saturation – sO2, actual base excess Cbase – B, standard base excess Cbase – Ecf and electrolytes (Na+, K+, Ca2+, Cl- and HCO3- – bicarbonate), while total proteins – TP and albumin ALB were determined in the serum. Also, strong ion difference - SID, z value, anion gap - AG, weak anions, and cations - ATOTtp and ATOTalb, strong ion gap - SIG, unmeasured anions – XA and globulin concentrations were calculated. A significant effect of the lactation stage on most of the acid-base parameters in the blood of the Lacaune sheep was determined, except for pCO2, Cl-, z values and the SID. A significant increase of pO2, sO2, ATOTtp, ATOTalb, AG, SIGalb, SIGtp, XA, Na+, total proteins and albumins, as well as the decreased concentrations of K+ and Ca2+, were determined in the blood of the Lacaune sheep during lactation. During the medium stage of lactation, significant changes were determined in most of the acid-base parameters in the blood of the Lacaune sheep when compared to the other stages. A lactation stage may significantly affect the acid-base balance parameters in the blood of the Lacaune sheep, although the calculations of SIG, base excess (BE), and unmeasured anion (XA) values should also be included for the obtainment of a more comprehensive picture of the acid-base balance.

Genotype-phenotype analysis and prognosis in children with primary distal renal tubular acidosis

Objective: The purpose of this study was to investigate the relationship between genotypes and clinical phenotypes of primary distal renal tubular acidosis (dRTA) in children. Methods: Clinical information, genetic testing information and follow-up data (until March 2021) of children with dRTA from Children's Hospital of Chongqing Medical University (from January 2010 to December 2020) were analyzed retrospectively. According to different pathogenic genes, patients were divided into SLC4A1 gene and ATP6V0A4+ATP6V1B1 gene groups. Age at onset, clinical manifestations and laboratory findings were compared. Self-comparisons of height standard deviation score (HtSDS), weight standard deviation score (WtSDS), blood pH and serum potassium before and after treatment were tested. T-test, Fisher's exact test and rank sum test were used to analyze among groups. Results: Among 27 children with dRTA (16 boys and 11 girls), the age of onset was 33.4 (10.0, 36.0) months.There were 22 patients (81%) with SLC4A1 gene variation, 3 patients (11%) with ATP6V1B1 gene variation and 2 patients (8%) with ATP6V0A4 gene variation. Totally 22 patients (81%) with renal calcium deposition, 19 patients (70%) hypokalemia, 18 patients (67%) short stature, 16 patients (59%) malnutrition, 16 patients (59%) rickets, and 15 patients (56%) polydipsia and polyuria. Noteworthily, the genotyping results indicated that the age at onset in SLC4A1 gene group was older than that in ATP6V0A4+ATP6V1B1 gene group, with a statistically significant difference (27.3 (12.0, 36.0) vs. 8.2 (2.5, 15.0) months, H=6.33, P=0.012). However, there were no significant differences in clinical manifestations or laboratory test results (all P>0.05). Furthermore, the course of disease was 3.9 (1.3, 6.0) years and the follow-up period was 3.1 (1.0, 4.5) years in 27 patients. In addition, there were no significant differences in recovery rate of clinical manifestations and last laboratory findings between SLC4A1 gene group and ATP6V0A4+ATP6V1B1 gene group (all P>0.05). HtSDS and WtSDS of those patients significantly increased after treatment (-3.2±1.9 vs. -2.1±1.1, -2.5±1.5 vs. 0±1.9, t=-2.94, -5.44, both P<0.01). Serum K+ and blood pH were restored eventually ((3.2±0.5) vs. (4.0±0.5) mmol/L, 7.27±0.07 vs. 7.37±0.07, t=-4.92, -5.25, both P<0.01). Totally 14 patients had normalized serum potassium, 12 patients had normalized blood pH, but only 4 patients had normalized serum bicarbonate concentration and normal base excess. Conclusions: The age of onset of patients who had SLC4A1 gene mutation was older than that of patients with ATP6V0A4 gene and ATP6V1B1 gene mutations. However, there was no obvious correlation between the condition and prognosis of the dRTA patients and pathogenic genes. Early diagnosis, early treatment, regular follow-up and timely adjustment of the dosage of medication can significantly improve the prognosis of dRTA in children. Serum bicarbonate concentration and actual base excess might not be the necessory indicators to assess clinical recovery.

Transplanted Kidney Increases Nitric Oxide Formation With Metabolic Acidosis Reduction.

As a vasodilator, nitric oxide is considered to play a significant role in the homeostatic regulation of renal hemodynamics. To test the hypothesis that a kidney graft is capable of producing nitric oxide immediately after renal transplant surgery, we examined the possibility that it positively affects local metabolic acidosis. In kidney transplant recipients, we analyzed renal vein and central vein blood samples, which reflect local and systemic metabolic alterations, respectively. Samples were taken immediately after kidney recirculation (that is, the first blood passing through after clamps are released) and at 5, 15, and 30 minutes thereafter. Levels of nitric oxide metabolites (nitrites, nitrates, and their sum), malondialdehyde (an indicator of oxidative damages), and parameters of acid-base balance (pH level, actual excess base, hemoglobin, actual bicarbonate, partial pressure of carbon dioxide, partial pressure of oxygen) were analyzed. Living kidney donors (the recipients' parents) were controls. In renal vein samples, nitrates and the sum of nitrites and nitrates were significantly higher than that shown in control (P < .001) and central vein (P < .05) samples, suggesting an immediate increase in nitric oxide production in the transplanted organ. Metabolic acidosis occurred in both the renal and central vein, indicated by decreased pH and actual bicarbonate level as well as by negative actual base excess level. Only in the renal vein was an increased nitrite and nitrate associated with a reduction of negative actual excess base, thereby suggesting a decrease in anion formation. Transplanted kidneys increase nitric oxide production immediately after organ transplant surgery, which positively affects local metabolic acidosis. The mechanism for this effect is likely local circulation improvement.

Controlled delay of the expulsive phase of foaling affects sympathoadrenal activity and acid base balance of foals in the immediate postnatal phase

Stress at foaling has been demonstrated to delay birth. In this study, we followed the hypothesis that even a short delay of foaling increases catecholamine and cortisol release in foals, induces acidosis and impairs neonatal adaptation. Foaling was prolonged for 5 min by transferring mares to an unfamiliar environment at rupture of the allantochorion (group delay, n = 6) while control mares (n = 5) were left undisturbed. In their foals, times from birth to first standing and first suckling, heart rate, heart rate variability (HRV) and salivary cortisol concentration were analysed. Blood for analysis of epinephrine, norepinephrine, hematology and blood gases was collected directly and 30 min after birth. Statistical comparisons were made by repeated measures ANOVA. Times to first standing and suckling did not differ between groups. Fetal heart rate remained unchanged during birth and increased within 15 min postnatum (p < 0.001) while HRV decreased during the first hour of life in foals of both groups (p < 0.05). Immediately after birth, actual base excess was lower in foals with delayed birth than in control foals (p < 0.05). Epinephrine concentration immediately after birth was higher in group delay foals and increased from 0 to 30 min after birth in control foals (time p < 0.001, time x group p = 0.001). Cortisol concentration peaked at 1 h after birth in both groups (p < 0.001). Leukocyte and PMN count decreased from 0 to 30 min after birth (p < 0.001). In conclusion, a 5-min delay at foaling affected epinephrine release and acid base balance, but was without further effect on neonatal adaptation.

Kardiyopulmoner Baypas ile Koroner Arter Cerrahisi Uygulanan Hastalarda Serebral Oksijenizasyonun ve Doku Perfüzyonunun Değerlendirilmesi

Objective: We aimed to determine whether there is a correlation between perfusion parameters [Lactate (lac), venoarterial carbondioxide gradient (ΔpCO2), central venous oxygen saturation (ScVO2)] and the relationship between these parameters and cerebral oxygenation in normothermia (T2), hypothermia (T3) and re-warming (T4) periods in cardiopulmonary bypass procedure (CPB). Material and Methods: Forty patients aged 19-78 years who were scheduled for elective coronary artery bypass surgery were included in the study. Mean arterial pressure (MAP), cerebral oxygenation (rSO2), periferic oxygen saturation (SpO2) values were recorded and by taking blood samples from arterial cannula and central venous catheter simultaneously; hematocrit (Htc), ΔpCO2, lac, ScVO2, actual base excess (aBE), bicarbonate (HCO3) values were recorded in T1 (after anesthesia induction and central venous catheterization), T2 (normothermia, 36oC, at the start of CPB), T3 (hypotermia, 32oC) and in T4 (at the end of CPB, rewarming, 36oC). Results: Between ΔpCO2-lac values, only positive correlation was found in T4 and there was no correlation between them at other times. There was significant negative correlation between rSO2 and lac in T1, T3 and T4, but no significant correlation was found between rSO2-ΔpCO2 parameters at any time. The correlations of lac and ΔpCO2 with cross-clamp and CPB durations were positive, whereas the correlations between ScVO2 and rSO2 with cross-clamp and CPB durations were negative. Conclusion: ΔpCO2 is not an early indicator of hypoperfusion in patients undergoing CPB in accordance with the literature and the lactate level is a guiding parameter in reporting the perfusion status. We recommend the intraoperative use of cerebral oximetry to prevent the brain from being affected by hypoperfusion during CPB and to prevent postoperative neurocognitive disorders in patients.

Scientific Progress or Regress in Sports Physiology?

In modern societies there is strong belief in scientific progress, but, unfortunately, a parallel partial regress occurs because of often avoidable mistakes. Mistakes are mainly forgetting, erroneous theories, errors in experiments and manuscripts, prejudice, selected publication of "positive" results, and fraud. An example of forgetting is that methods introduced decades ago are used without knowing the underlying theories: Basic articles are no longer read or cited. This omission may cause incorrect interpretation of results. For instance, false use of actual base excess instead of standard base excess for calculation of the number of hydrogen ions leaving the muscles raised the idea that an unknown fixed acid is produced in addition to lactic acid during exercise. An erroneous theory led to the conclusion that lactate is not the anion of a strong acid but a buffer. Mistakes occur after incorrect application of a method, after exclusion of unwelcome values, during evaluation of measurements by false calculations, or during preparation of manuscripts. Co-authors, as well as reviewers, do not always carefully read papers before publication. Peer reviewers might be biased against a hypothesis or an author. A general problem is selected publication of positive results. An example of fraud in sports medicine is the presence of doped subjects in groups of investigated athletes. To reduce regress, it is important that investigators search both original and recent articles on a topic and conscientiously examine the data. All co-authors and reviewers should read the text thoroughly and inspect all tables and figures in a manuscript.

The use of a double‐lumen central venous catheter for airway management in pediatric patients undergoing laryngeal papillomatosis surgery

To evaluate the efficacy and safety of a spontaneous ventilation anesthesia technique with insufflation of oxygen and volatile agent through a double-lumen central venous catheter (DLCVC) in pediatric patients undergoing suspension laryngoscopic surgery for laryngeal papillomatosis. Thirty-six pediatric patients with laryngeal papillomatosis undergoing suspension laryngoscopic surgery were anesthetized with oxygen and volatile anesthetic insufflation while spontaneously breathing. Anesthesia was induced by inhalation of 8% sevoflurane in oxygen by mask. Atropine, dexamethasone, lidocaine, and midazolam were administered intravenously. The tip of a 7Fr DLCVC was inserted below the glottis after placement of the laryngoscope and establishing suspension. Anesthesia was maintained with insufflation of 4-6% sevoflurane and oxygen with a total fresh gas flow of 6 l·min(-1) through the 14G (larger lumen) of the DLCVC. Endtidal carbon dioxide tension (PetCO2) was monitored using the other lumen of the DLCVC, which was connected to the CO2 sampling line. Duration of the procedure as well as total anesthesia time was recorded. Electrocardiography (ECG), heart rate (HR), mean arterial pressure (MAP), oxygen saturation (SpO2), and PetCO2 were also monitored. Arterial blood was sampled for blood gas analysis including pH, PaO2 , PaCO2 , and actual base excess (ABE). Complications, including intraoperative patient movement, hypoxemia (SpO2 < 95% during oxygen insufflation), nausea, vomiting, bronchospasm, and arrhythmias, were recorded. There was a significant increase in PetCO2 and PaCO2 (P values <0.05) as well as a decrease in ABE, pH, and PaO2 (P values <0.05) in samples collected before and after surgery. MAP, HR, and SpO2 after surgery were not significantly different from after induction values (P values >0.05). During surgery, SpO2 < 95% in three cases and body movements in three cases were observed. No patient had any other of the complications previously described. Furthermore, no postsurgical endotracheal intubation was needed in any patient. After establishing an adequate depth of anesthesia, a spontaneous ventilation anesthesia technique with insufflation of oxygen and volatile agent through a DLCVC is feasible in pediatric patients undergoing suspension laryngoscopic surgery for laryngeal papillomatosis.

Influence of spurious hemolysis on blood gas analysis

Although the prevalence of hemolyzed samples referred for blood gas analysis is as high as 4%, no studies have assessed the bias introduced by spurious erythrocyte breakdown, nor it is known which parameters are mostly influenced and to what extent. This study was hence planned to assess the influence of spurious hemolysis on venous blood gas analysis. Venous blood was collected from nine healthy volunteers in sodium heparin tubes and divided in two aliquots of 3 mL. The former aliquot was mechanically hemolyzed by aspiration with 0.5 mL insulin syringe equipped with 30 gauge needle. One milliliter of all aliquots was tested for hemoglobin, pH, oxygen partial pressure (pO₂), partial pressure of carbon dioxide (pCO₂), bicarbonate (HCO³⁻), oxygen tension at 50% hemoglobin saturation (p50), oxygen saturation (sO₂), actual base excess (ABE), carboxyhemoglobin (COHb), methemoglobin (metHb), ionized calcium (Ca²⁺) and potassium, on ABL800 flex. The remaining 2 mL of blood were centrifuged, plasma separated and tested for hemolysis index. The concentration of cell-free hemoglobin increased from <0.5 g/L to 8.9±1.5 g/L in hemolyzed aliquots. In hemolyzed blood, significant decreases were found for pH (-0.2%), pO₂ (-4.9%), sO₂ (-4.9%), COHb (-11%) and Ca²⁺ (-7.0%), whereas significant increases were observed for pCO₂ (+4.1%), HCO³⁻ (+1.4%) and potassium (+152%). Clinically meaningful bias was found for pO₂, pCO₂, Ca²⁺ and potassium. Spurious hemolysis is likely to introduce meaningful biases in blood gas analysis, hence manufacturers of blood gas analyzers should develop instrumentation capable of identifying interfering substances in whole blood. The presence of spurious hemolysis should also be suspected whenever test results do not reflect the clinics.

Intrapartum fetal asphyxia: study of umbilical cord blood lactate in relation to fetal heart rate patterns

To correlate between umbilical artery cord blood lactate and acid-base status with intrapartum fetal heart rate monitoring, and to measure the reliability of umbilical cord blood lactate for prediction of early neonatal outcome. Sixty-six participants with intrapartum abnormal fetal heart rate monitoring and 60 participants with normal intrapartum recordings were recruited. The abnormal recordings included late onset, atypical variable and simple variable decelerations. After delivery, the arterial cord blood lactate, pH, actual base excess (ABE), and Apgar score were measured in all participants. There was significant inverse correlation between cord lactate and pH and ABE in all participants (correlation coefficient = -0.7, p < 0.0001). The cord lactate was significantly higher in the late onset and atypical variable decelerations groups compared to control (p < 0.0001). There was no significant correlation between the Apgar score and blood lactate in all groups; however, the sensitivity and specificity of cord lactate to predict low score at 5 min were higher in comparison to cord pH. Umbilical cord blood lactate is a reliable marker for intrapartum fetal asphyxia compared to cord acid-base status with better prediction for newborns with low Apgar score.

Prediction of fetal base excess values at birth using an algorithm to interpret fetal heart rate tracings: a retrospective validation

To evaluate whether a standardised algorithm to interpret fetal heart rate (FHR) tracings during the entire length of labour can predict umbilical artery base excess at birth, and to investigate its inter- and intra-observer reproducibility. Retrospective study. Obstetrics and gynaecology department at a tertiary referral centre in a university hospital. Group 1: 152 consecutive, generally low-risk, labouring women. Group 2: mixed group of 30 women who delivered a fetus with pH < 7.00 and 30 women who delivered a fetus with pH ≥ 7.00. Intrapartum FHR tracings were retrospectively and blindly evaluated by two independent assessors using an algorithm proposed by Ross and Gala to predict fetal base excess at birth. The accuracy in predicting the base excess values of newborns was expressed as the proportion of FHR tracings in which the operator was able to correctly calculate the actual base excess at birth (approximation of ± 2 mmol/l). Inter- and intra-observer reproducibility were estimated using the Pearson correlation coefficient. In the group of 152 low-risk labouring women, the two assessors correctly predicted the umbilical artery base excess in 73.1 and 76.3% of cases, respectively. Inter-observer (Pearson correlation coefficient = 0.75) and intra-observer (Pearson correlation coefficient = 0.80 and 0.82 for the first and second assessor, respectively) reproducibility was very good. In the 30 fetuses that were acidemic, the first and second observers correctly predicted base excess values in 23 (76.7%) and 21 (70%) cases, respectively (inter-observer reproducibility, Pearson correlation coefficient = 0.72). The algorithm proposed by Ross and Gala may be a valuable tool to estimate changes in umbilical base excess during active labour, with a high inter- and intra-observer reproducibility.

Alteration of anion gap and strong ion difference caused by hydroxyethyl starch 6% (130/0.42) and gelatin 4% in children

Synthetic colloid administration is a common practice for preventing perioperative hypovolemia and consecutive circulatory failure in children. This prospective, randomized study was conducted to investigate the effects of two different unbalanced synthetic colloid solutions on acid-base equilibrium in children. Fifty pediatric patients (aged 0-12 years) scheduled for major pediatric surgery were randomized to receive either 10 ml x kg(-1) of 6% hydroxyethyl starch solution 130/0.42 (HES) or 4% modified fluid gelatin (GEL) to maintain adequate systemic hemodynamics. Before and after colloid administration, a blood sample was collected to analyze hemoglobin, hematocrit, electrolytes, and acid-base parameters. The anion gap and the strong ion difference (SID) were calculated using standard formulas. Both HES and GEL administration caused a significant increase in plasma chloride concentration (P < 0.01) and an accompanying decrease in SID (P < 0.01). In the HES group, the anion gap decreased significantly (P < 0.01) whereas the anion gap remained stable in the GEL group. In both groups, initial actual base excess and pH did not change significantly after colloid administration. Moderate intraoperative plasma replacement with unbalanced synthetic colloids HES and GEL leads to a decrease in SID and, in the case of HES, to a significant decrease in the anion gap in children. These alterations may result in a possible misinterpretation when the anion gap and SID are used for differential diagnosis of metabolic disturbances during major pediatric surgery.

Umbilical cord blood lactate: A valuable tool in the assessment of fetal metabolic acidosis

Objective The aim of the present study was (1) to evaluate the relationship between umbilical cord arterial blood lactate and pH, standard base excess (SBE), and actual base excess (ABE) at delivery and (2) to suggest a cut-off level of umbilical cord arterial blood lactate in predicting fetal asphyxia using ROC-curves, where an ABE value less than −12 was used as “gold standard” for significant intrapartum asphyxia. Study design This is a descriptive study of umbilical cord arterial blood samples from 2554 singleton deliveries. The deliveries took place at the Department of Obstetrics and Gynaecology, Hvidovre University Hospital, Copenhagen, Denmark where umbilical cord blood sampling and blood gas analysis is part of the routine assessment of all newborns. Results We found significant correlations between lactate and pH ( r = −0.73), lactate and SBE ( r = −0.76), and lactate and ABE ( r = −0.83). ROC-curves suggested a lactate cut-off level of 8 mmol/l for indicating intrapartum asphyxia. Conclusion Lactate in arterial umbilical cord blood might be a more direct and accordingly more correct indicator of fetal asphyxia at delivery than pH and SBE (or ABE). Its potential as a predictor of neonatal outcome needs to be evaluated in future studies.

The acid–base impact of free water removal from, and addition to, plasma

Water, compared with plasma at a pH of 7.4, is a weak acid. The addition of free water to a patient should have an acidifying effect (dilutional acidosis) and the removal of it, an alkalinizing effect (concentrational alkalosis). The specific effects of free water loss or gain in a relatively complex fluid such as plasma has, to the authors' knowledge, not been reported. This information would be useful in the interpretation of the effect of changes in free water in patients. Plasma samples from goats were either evaporated in a tonometer to 80% of baseline volume or hydrated by the addition of distilled water to 120% of baseline volume. The pH and partial pressure of carbon dioxide, sodium, potassium, ionized calcium, chloride, lactate, phosphorous, albumin, and total protein concentrations were measured. Actual base excess (ABE), standard bicarbonate, anion gap, strong ion difference, strong ion gap, unmeasured anions, and the effects of sodium, chloride, phosphate, and albumin changes on ABE were calculated. Most parameters changed 20% in proportion to the magnitude of dehydration or hydration. Bicarbonate concentration, however, increased only 11% in the evaporation trial and decreased only -2% in the dehydration trial. The evaporation trial was associated with a mild, but significant, metabolic alkalotic effect (ABE increased 3.2 mM/L), whereas the hydration trial was associated with a slight, insignificant metabolic acidotic effect (ABE decreased only 0.6 mM/L). The calculated free water ABE effect (change in sodium concentration) was offset by opposite changes in calculated chloride, lactate, phosphate, and albumin ABE effects.

Study for acid-base homeostasis in children with growth hormone deficiency

To study the difference of plasma actual bicarbonate between the children with growth hormone deficiency (GHD) and idopathatic short stature (ISS) and to value the plasma bicarbonate standard deviation scores (SDS) in diagnosis of GHD. Forty-seven short stature children were divided into two groups (GHD and ISS) according to the peak GH response to provocative test. Plasma actual bicarbonate concentrations anion gap (AG), base excess and electrolytes were measured in 47 children with short stature before GH provocative tests. The mean plasma actual bicarbonate concentrations, bicarbonate SDS were (22.60+/-1.29)mmol/L and -0.27+/-0.98 respectively in GHD children, which were significantly lower than those of ISS children (P<0.01), whereas AG was higher than that of ISS children [(11.73+/-4.52 vs 7.87+/-1.70) mmol/L], P<0.01. Seventy-two percent of patients with bicarbonate SDS<or=1 s were diagnosed as GHD. Plasma actual bicarbonate concentrations and bicarbonate SDS are lower in patients with GHD than those in patients with idopathatic short stature. Evaluation of plasma bicarbonate SDS of short stature children can predict the probability of GHD, especially when bicarbonate SDS is less than 1 s.

Pathogenesis CO 2 Pneumoperitoneum-Induced Metabolic Hypoxemia in a Rabbit Model

Study Objective To investigate the effects of carbon dioxide (CO 2) pneumoperitoneum-induced changes in blood gases, acid-base balance, and oxygen homeostasis in rabbits. Design Prospective, randomized, controlled study (Canadian Task Force classification I). Setting University training and teaching center. Subjects Twenty-six adult female New Zealand white rabbits. Interventions Anesthesia and pneumoperitoneum. Measurements and Main Results In anesthetized rabbits arterial blood gases, acid-base balance, oxygenation values, and lactate concentrations were assayed during 2 hours. Spontaneous breathing, superficial and optimal ventilation without pneumoperitoneum, and with pneumoperitoneum at low (6 mm Hg) and higher (10 mm Hg) insufflation pressures were compared. The CO 2 pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis. Carboxemia with increasing end-tidal CO 2 and partial pressure of CO 2 (p< 0.001), acidosis with decreasing pH (p< 0.001), and base deficiency with decreasing actual base excess (p< 0.001), standard base excess and standard bicarbonate and acid excess with increasing hydrogen bicarbonate (p<0.05 and <0.01) were found. Desaturation (p <0.01) with decreasing oxyhemoglobin p <0.05) and hemoglobin oxygen affinity (p <0.01) were also found. Carboxemia with acidosis was more pronounced with higher (p <0.01) than with lower (p >0.05) intraperitoneal pressures, and also with spontaneous breathing (p <0.05) and superficial ventilation (p< 0.001) than with optimal ventilation, resulting in metabolic hypoxemia. Conclusion In superficially ventilated and spontaneously breathing rabbits, CO 2 pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis, resulting in metabolic hypoxemia. With optimal ventilation and low intraperitoneal pressure carboxemia, respiratory acidosis, and changes in oxygen metabolism were minimal.

Reduction of CO(2)-pneumoperitoneum-induced metabolic hypoxaemia by the addition of small amounts of O(2) to the CO(2) in a rabbit ventilated model. A preliminary study.

CO(2)-pneumoperitoneum used in endoscopic surgery induces system effects by CO(2) absorption. This study investigated the effect of the addition of O(2) to CO(2)-pneumoperitoneum, upon CO(2) absorption. The effect of a pneumoperitoneum using 100% CO(2) or 94% CO(2) + 6% O(2) upon arterial blood gases, acid base and O(2) homeostasis was evaluated. In series A suboptimal ventilation and a pneumoperitoneum pressure (PP) of 10 mmHg was used. In series B adequate ventilation and PP of 6 mmHg was used. CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis i.e. increasing pCO(2), HCO(3)(P < 0.001) and lactate concentrations (P < 0.05) and decreasing pH, actual base excess and standard bicarbonate (P < 0.001), resulting in metabolic hypoxaemia with desaturation, lower pO(2) (P < 0.001) and O(2)Hb (P < 0.05). These effects were more pronounced with higher PP and suboptimal ventilation. CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis resulting in metabolic hypoxaemia. The addition of 6% of O(2) to the CO(2)-pneumoperitoneum prevented these effects to a large extent. If these preliminary data are confirmed in the human, the addition of a few percent of O(2) to CO(2) could become important for endoscopic surgery of long duration, especially in obese patients with limited cardiorespiratory adaptation and steep Trendelenburg.

Effects of xylazine on acid-base balance and arterial blood-gas tensions in goats under different environmental temperature and humidity conditions.

The effects of acute exposure to 3 different temperature and humidity conditions on arterial blood-gas and acid-base balance in goats were investigated after intravenous bolus administration of xylazine at a dose of 0.1 mg/kg. Significant (P<0.05) changes in the variables occurred under all 3 environmental conditions. Decreases in pH, partial pressure of oxygen and oxyhaemoglobin saturation were observed, and the minimum values for oxygen tension and oxyhaemoglobin saturation were observed within 5 min of xylazine administration. The pH decreased to its minimum values between 5 and 15 min. Thereafter, the variables started to return towards baseline, but did not reach baseline values at the end of the 60 min observation period. Increases in the partial pressure of carbon dioxide, total carbon dioxide content, bicarbonate ion concentration, and the actual base excess were observed. The maximum increase in the carbon dioxide tension occurred within 5 min of xylazine administration. The increase in the actual base excess only became significant after 30 min in all 3 environments, and maximal increases were observed at 60 min. There were no significant differences between the variables in the 3 different environments. It was concluded that intravenous xylazine administration in goats resulted in significant changes in arterial blood-gas and acid-base balance that were associated with hypoxaemia and respiratory acidosis, followed by metabolic alkalosis that continued for the duration of the observation period. Acute exposure to different environmental temperature and humidity conditions after xylazine administration did not influence the changes in arterial blood-gas and acid-base balance.