A basic solution for a complex problem: does treatment of metabolic acidosis slow CKD progression?

PURPOSE OF THIS REVIEW

Metabolic acidosis is frequently encountered in patients with chronic kidney disease (CKD), with increasing prevalence as kidney function worsens. Treating electrolyte disturbances is the sine qua non of Nephrologists, and alkali therapy to normalize serum bicarbonate levels and slow progression of kidney disease has been embedded in clinical practice guidelines for decades on the basis of animal models and controversial clinical trials. This review will critically appraise the literature base for this recommendation and determine whether the available evidence supports this common practice, which is a timely endeavor considering the impending demotion of metabolic acidosis treatment from recommendation to practice point in forthcoming KDIGO guidelines.

RECENT FINDINGS

Earlier, open-label, studies supporting the utility of sodium bicarbonate therapy to slow progression of chronic kidney disease have been challenged by more recent, blinded, studies failing to show benefit on CKD progression. This was further demonstrated in the absence of concomitant sodium administration with the hydrochloric acid binder veverimer, which failed to demonstrate benefit on renal death, end stage kidney disease or 40% reduction in estimated glomerular filtration rate in a large multicenter trial.

SUMMARY

The current body of literature does not support the routine treatment of metabolic acidosis in patients with CKD and the authors agree with the forthcoming KDIGO guidelines to de-emphasize this common practice.

Arterial Blood Gases and Acid-Base Regulation

Disorders of acid-base status are common in the critically ill and prompt recognition is central to clinical decision making. The bicarbonate/carbon dioxide buffer system plays a pivotal role in maintaining acid-base homeostasis, and measurements of pH, PCO2, and HCO3 - are routinely used in the estimation of metabolic and respiratory disturbance severity. Hypoventilation and hyperventilation cause primary respiratory acidosis and primary respiratory alkalosis, respectively. Metabolic acidosis and metabolic alkalosis have numerous origins, that include alterations in acid or base intake, body fluid losses, abnormalities of intermediary metabolism, and renal, hepatic, and gastrointestinal dysfunction. The concept of the anion gap is used to categorize metabolic acidoses, and urine chloride excretion helps define metabolic alkaloses. Both the lungs and kidneys employ compensatory mechanisms to minimize changes in pH caused by various physiologic and disease disturbances. Treatment of acid-base disorders should focus primarily on correcting the underlying cause and the hemodynamic and electrolyte derangements that ensue. Specific therapies under certain conditions include renal replacement therapy, mechanical ventilation, respiratory stimulants or depressants, and inhibition of specific enzymes in intermediary metabolism disorders.

Electrolyte imbalance in COVID-19 patients admitted to the Emergency Department: a case-control study

In patients visiting the emergency department (ED), a potential association between electrolytes disturbance and coronavirus disease 2019 (COVID-19) has not been well studied. We aim to describe electrolyte disturbance and explore risk factors for COVID-19 infection in patients visiting the ED. We carried out a case-control study in three hospitals in France, including adult ED inpatients (≥ 18 years old). A total of 594 ED case patients in whom infection with COVID-19 was confirmed, were matched to 594 non-COVID-19 ED patients (controls) from the same period, according to sex and age. Hyponatremia was defined by a sodium of less than 135 mmol/L (reference range 135-145 mmol/L), hypokalemia by a potassium of less than 3.5 mmol/L (reference range 3.5-5.0 mmol/L), and hypochloremia by a chloride of less than 95 mmol/L (reference range 98-108 mmol/L). Among both case patients and controls, the median (IQR) age was 65 years (IQR 51-76), and 44% were women. Hyponatremia was more common among case patients than among controls, as was hypokalemia and hypochloremia. Based on the results of the multivariate logistic regression, hyponatremia, and hypokalemia were associated with COVID-19 among case patients overall, with an adjusted odds ratio of 1.89 [95% CI 1.24-2.89] for hyponatremia and 1.76 [95% CI 1.20-2.60] for hypokalemia. Hyponatremia and hypokalemia are independently associated with COVID-19 infection in adults visiting the ED, and could act as surrogate biomarkers for the emergency physician in suspected COVID-19 patients.

Early-Life Multiple Sevoflurane Exposures Alleviate Long-term Anxiety-Like Behaviors in Mice via the proBDNF/ERK Pathway

Early-life multiple anesthetics exposure causes neurotoxicity and hence cognitive dysfunction on developing brain. However, the effects of early-life multiple sevoflurane exposures on emotional changes, especially upon stress, are far beyond understood. In young male C57BL6/J mice, the present study showed that 3% sevoflurane inhalation for 2 h in three consecutive days did not influence anxiety-like behaviors as measured by open field test, light dark transition, and elevated plus maze test. In addition, foot shocks stress induced both the short- and long-term anxiety-like behaviors. However, triple sevoflurane exposures ameliorated the long-term anxiety-like behaviors induced by the foot shocks. In parallel, foot shocks stress upregulated the expression of phosphorylated extracellular signal-regulated kinase (p-ERK) and brain-derived neurotrophic factor precursor (proBDNF) in the anterior cingulate cortex (ACC), which were significantly inhibited by triple sevoflurane exposures. Immunofluorescence further indicated that the increased p-ERK was mainly expressed in the proBDNF-positive staining cells. Intra-ACC injection of recombinant proBDNF protein upregulated the p-ERK expression and blocked the anxiolytic effect of sevoflurane exposure on long-term anxiety-like behaviors. Therefore, our study demonstrated that multiple sevoflurane exposures alleviate long-term anxiety-like behaviors upon acute stress in young mice by inhibiting proBDNF-ERK signaling in the ACC.

The Treatment of Metabolic Acidosis: An Interactive Case-Based Learning Activity

Introduction

Metabolic acidosis is a dangerous and potentially life-threatening condition encountered in the inpatient and emergency department setting. Metabolic acidoses due to renal failure, bicarbonate losses, or lactic acidosis are common conditions, and the appropriate medical management of each is relevant to any inpatient medical provider. Therefore, we created a learning activity that utilizes blackboard-style videos followed by an interactive case-based learning session to help the medical student recognize, diagnose, and manage common causes of metabolic acidosis.

Methods

We organized this learning activity by assigning digital videos, followed by application in an interactive team-based format. We created electronic blackboard-style videos and a quiz to assess medical knowledge related to concepts discussed in the videos. Next, we created case resources that facilitate an interactive case-based teaching session so the learners could apply their knowledge and simulate the management of metabolic acidosis.

Results

We implemented this activity for 34 medical students. All students viewed the videos prior to the in-class session. In a pre/post assessment of medical knowledge, we observed a significant improvement in quiz scores. Next, we successfully facilitated the case-based active learning session, allowing the assessment of higher-order cognitive skills related to management of patients with metabolic acidosis. Our medical students felt highly satisfied and competent at the completion of our course.

Discussion

Our medical students rated this as an excellent learning activity. Others may find this activity useful within the context of any course or rotation related to patients with metabolic acidosis.

Increased compensatory kidney workload results in cellular damage in a short time porcine model of mixed acidemia - Is acidemia a 'first hit' in acute kidney injury?

Acute kidney injury (AKI) corrupts the outcome of about 50% of all critically ill patients. We investigated the possible contribution of the pathology acidemia on the development of AKI. Pigs were exposed to acidemia, acidemia plus hypoxemia or a normal acid-base balance in an experimental setup, which included mechanical ventilation and renal replacement therapy to facilitate biotrauma caused by extracorporeal therapies. Interestingly, extensive histomorphological changes like a tubular loss of cell barriers occurred in the kidneys after just 5 hours exposure to acidemia. The additional exposure to hypoxemia aggravated these findings. These ‘early’ microscopic pathologies opposed intra vitam data of kidney function. They did not mirror cellular or systemic patterns of proinflammatory molecules (like TNF-α or IL 18) nor were they detectable by new, sensitive markers of AKI like Neutrophil gelatinase-associated lipocalin. Instead, the data suggest that the increased renal proton excretion during acidemia could be an ‘early’ first hit in the multifactorial pathogenesis of AKI.

Combined effects of lung function, blood gases and kidney function on the exacerbation risk in stable COPD: Results from the COSYCONET cohort

RATIONALE

Alterations of acid-base metabolism are an important outcome predictor in acute exacerbations of COPD, whereas sufficient metabolic compensation and adequate renal function are associated with decreased mortality. In stable COPD there is, however, only limited information on the combined role of acid-base balance, blood gases, renal and respiratory function on exacerbation risk grading.

METHODS

We used baseline data of the COPD cohort COSYCONET, applying linear and logistic regression analyses, the results of which were implemented into a comprehensive structural equation model. As most informative parameters it comprised the estimated glomerular filtration rate (eGFR), lung function defined via forced expiratory volume in 1 s (FEV₁), intrathoracic gas volume (ITGV) and (diffusing capacity for carbon monoxide (DLCO), moreover arterial oxygen content (CaO₂), partial pressure of oxygen (PaCO₂), base exess (BE) and exacerbation risk according to GOLD criteria. All measures were adjusted for age, gender, body-mass index, the current smoking status and pack years.

RESULTS

1506 patients with stable COPD (GOLD grade 1-4; mean age 64.5 ± 8.1 y; mean FEV₁ 54 ± 18 %predicted, mean eGFR 82.3 ± 16.9 mL/min/1.73 m²) were included. BE was linked to eGFR, lung function and PaCO₂ and played a role as indirect predictor of exacerbation risk via these measures; moreover, eGFR was directly linked to exacerbation risk. These associations remained significant after taking into account medication (diuretics, oral and inhaled corticosteroids), whereby corticosteroids had effects on exacerbation risk and lung function, diuretics on eGFR, BE and lung function.

CONCLUSION

Even in stable COPD acid-base metabolism plays a key integrative role in COPD risk assessment despite rather small deviations from normality. It partially mediates the effects of impairments in kidney function, which are also directly linked to exacerbation risk.

Prevalence and predictors of intra-abdominal hypertension and compartment syndrome in surgical patients in critical care units at Kenyatta National Hospital

BACKGROUND

Intra-abdominal hypertension (IAH) affects almost every organ sytem.If it is not detected early and corrected, mortality would be high. The prevalence of IAH and abdominal compartment syndrome (ACS) at Kenyatta National Hospital (KNH) critical care units is not known. The aim of this sudy was to determine the prevalence and factors associated with development of IAH/ACS among critically ill surgical patients.

METHODS

This was a cross sectional descriptive study involving surgical patients in critical care units at KNH, carried out from March 2015 to October 2015. One hundred and thirteen critically ill and ventilated patients 13 years or older were recruited into the study. Krohn's intravesical method was used to measure intra- abdominal pressure (IAP). Measurements were done at first contact, then at 12 and 24 h. Additional parameters recorded included: laboratory tests such as serum bilirubin and total blood count as well as clinical parameters such as urine output, vital signs and peak airway pressure, among others. Frequency, means and standard deviation were used to describe the data. Categorical variables e.g. age, were analysed using Chi square test and continous variables using student 't' test and Mann Whitney test as appropriate RESULT: A total of 113 consecutive surgical patients admitted to the critical care units were recruited. Of our study population, 71.7% (by IAP max) and 67.3% (by IAP mean) had IAH. Abdominal compartment syndrome (ACS) developed in 4.4% of the population. The following factors were significant determinants of risk of IAH : amount of IV fluids over 24 h (3949.6 vs 2931.1, p = 0.003, adjusted OR 1.0 [1.0-1.002]), haemoglobin values at admission (9.9 vs 12.0, p = <0.012, adjusted OR 0.6 [0.4-0.9]), peak airway pressure (28.4 vs 17.3; p = 0.018, adjusted OR 1.6 [1.1-2.4]) and synchronised intermittent mandatory ventilation (SIMV) (60 vs 32; p = 0.041, adjusted OR 1.4 [0.78-2.04]). Of those who had IAH; age, amount of iv fluids over 24 h, fluid balance and ventilator mode were significant determinants of risk of progression to ACS .

CONCLUSION

The prevalence of intraabdominal hypertension and abdominal compartment syndrome at KNH is high. Clinical parameters pertaining to fluids administration and ventilator mode are siginificant determinants.

Dietary Acid-Base Load and Risk of Chronic Kidney Disease in Adults: Tehran Lipid and Glucose Study

INTRODUCTION

The objective was to examine whether dietary acid load was associated with chronic kidney disease (CKD) in adults.

MATERIALS AND METHODS

The cross-sectional analyses included 4564 participants, aged 20 years and older, who participated in the 4th phase of the Tehran Lipid and Glucose Study and had complete dietary and serum creatinine data. Dietary data were obtained from using a 147-item food-frequency questionnaire. Dietary acid load was calculated as the potential renal acid load (PRAL). Anthropometrics, blood pressure, and fasting plasma glucose, and lipids were measured. Chronic kidney disease was defined as an estimated glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 calculated using the Modification of Diet in Renal Disease equation. Risk of CKD was obtained in quartiles of PRAL with logistic recreation.

RESULTS

The mean dietary PRAL of the participants was -22.0 mEq/d. After adjustment for age, sex, and body mass index, the odds ratio for CKD in the highest compared to the lowest quartile of PRAL was 1.38 (95% confidence interval [CI], 1.02 to 1.83). After additional adjustment for energy intake and smoking, the odds ratio for CKD in the 4th quartile of PRAL compared to the 1st was 1.42 (95% CI, 1.06 to 1.91). In the final model, after additional adjustment for dietary intake of total fat, carbohydrate, dietary fiber, fructose, sodium, diabetes mellitus, and hypertension, the risk of CKD in the highest dietary PRAL category, compared to the lowest, increased by 42%.

CONCLUSIONS

After adjusting for possible confounding factors, we found that higher PRAL (more acidic diet) was associated with higher prevalent CKD in Iranian adults.

Use of different approaches of acid-base derangement to predict mortality in critically ill patients

BACKGROUND

There have been controversial data regarding the application of acid-base analysis based on Stewart methodology to predict clinical outcome in different populations.

OBJECTIVE

To compare predictive ability of the physicochemical approach and the traditional bicarbonate approach of acid-base analysis in critically ill patients in relation to 28-days mortality and to evaluate the use of the physico chemical approach determined by the strong ion gap (SIG) in 1) medical compared to surgical critically ill patients; and 2) sepsis compared to non-sepsis patients.

MATERIAL AND METHOD

This retrospective cohort study included 410 critically ill patients in the adult medical and surgical intensive care units (ICU) at a tertiary care hospital over a 2-year period. For each patient, values derived from the bicarbonate approaches including anion gap (AG), corrected anion gap (cAG) and lactate and those obtained from the physicochemical approach like SIG were simultaneously computed at ICU admission. The comparison of predictive ability between different approaches was assessed by forward stepwise logistic regression and the area under the receiver operating characteristic (aROC) curves.

RESULTS

Of the 410 patents enrolled, 205 (50%) were admitted in the medical ICU and 226 patients (55%) were male. Overall 28-day mortality was 44.6% (183/410). The comparison between medical and surgical patients showed no difference in age (59 vs. 64 yr), APACHE II score (21 vs. 20), presence of sepsis (71% vs. 70%) and 28-day mortality (45% vs. 44%). Acid-base disturbance in non-survivors (n = 183) and survivors (n = 227) determined by pH (7.39 +/- 0.04 vs. 7.41 +/- 0.01), serum bicarbonate (16.0 +/- 6.1 vs. 17.9 +/- 7.4) and PaCO2 (32.4 +/- 13.4 vs. 29.4 +/- 8.2) were comparable. However non-survivors had higher levels of SIG (9.7 +/- 6.2 vs. 6.4 +/- 5.2) and cAG (27.5 +/- 8.8 vs. 20.3 +/- 8.6) than survivors did. According to a ROC curves, the predictive ability to discriminate between survivors and non-survivors of lactate, cAG AG and SIG are 0.77, 0.72, 0.68 and 0.67, respectively. Correlations between the SIG and values derived from bicarbonate approach are fair. There was no difference in SIG values between surgical and medical patients with the same severity scores. Sepsis patients (n = 291) had significantly higher SIG than non-sepsis patients (n = 129) did (8.81 +/- 6.38 vs. 5.74 +/- 4.14; p = 0.01).

CONCLUSION

Compared to the traditional approach, an alternative Stewart approach does not provide any greater advantage to predict mortality in the studied population. Because of complex calculation, the usefulness of such approach on the routine clinical practice may be limited.

Dyselectrolytemias and arrhythmias

Critical care patients are submitted to multiple derangements of vital parameters. Even in patients with a normally performing heart, its electrical activity can be strongly influenced by dyselectrolytemias, acid-base imbalance and aggressive drug therapy. In this paper, the basic principles of the electrophysiologic properties of the heart are reviewed, and the impact of dyselectrolytemias on heart excitability are underlined. Some clinically relevant aspects are described in greater depth, with respect to life-threatening arrhythmias.

Neurologic presentations of acid-base imbalance, electrolyte abnormalities, and endocrine emergencies

Accurate identification of nervous system dysfunction is vital in the assessment of any multisystem disorder. The neurologic manifestations of acid-base disturbances, abnormal electrolyte concentrations, and acute endocrinopathies are protean and typically determined by the acuity of the underlying derangement. Detailed history and physical examination may guide appropriate laboratory testing and lead to prompt and accurate diagnosis. Neurologic manifestations of primary and secondary systemic disorders are frequently encountered in all subspecialties of medicine. This article focuses on key neurologic presentations of respiratory and metabolic acid-base derangements and potentially life-threatening endocrinopathies.

Acid-base imbalance in uncomplicated ST-elevation myocardial infarction: the clinical role of tissue acidosis

Little information is available on acid-base imbalance in uncomplicated ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous intervention (PCI). We therefore assessed acid-base imbalance in 257 consecutive uncomplicated STEMI patients submitted to PCI to determine whether its evaluation could help in identifying patients at higher risk for in-hospital complications (acute pulmonary edema and dysrhythmias). A basic metabolic profile was performed at hospital admission, that is before PCI. After PCI, we measured: creatinine, uric acid and NT-pro BNP and serum electrolytes. Peak troponin I was also considered. Acidemia was present in 11 patients (4.2%), HCO(3) < 22 in 62 (24.1%). Base excess < -3 was detectable in 70 patients (27.2%), anion gap > 12 in 13 (5.1%), Cl/Na < 0.79 in 93 patients (38.5%). Patients with a Cl/Na < 0.79 had a lower LVEF (p = 0.042) and higher values of NT-pro-BNP (p = 0.019) and of latency (p = 0.029) together with a higher length of stay (p = 0.017) and a higher incidence of in-hospital complications (p = 0.017). At backward stepwise regression analysis, the following variables resulted independent predictors of in-hospital complications: base excess OR 1.47 (95% CI 1.04-2.10) p = 0.031; Cl/Na ratio O.R. 1.85 (95% CI 1.05-3.27) p = 0.035. In STEMI patients submitted to mechanical revascularization the evaluation of acid-base status and, in particular the detection of even mild degrees of acidosis may help in risk stratification for in-hospital complications. A Cl/Na < 0.79 ratio and a base excess are independent predictors for in-hospital complications.

[Non-traumatic rhabdomyolysis in medical practice]

Rhabdomyolysis, meaning "disintegration of striated muscle", is a potentially life-threatening syndrome resulting from release of muscular cell constituents into the circulation. The aim of this study is to determine frequence and causes of rhabomyolysis in internal medicine practice, as well as diagnostic and therapeutic discussions, based on a retrospective study in patients addressed to a medical clinic of an universitary emergency hospital.

RESULTS

The most common causes of rhabdomyolysis in general practice are represented by muscular trauma, muscle enzyme deficiencies, electrolyte abnormalities, infections, drugs, toxins and endocrine disorders. Frequent encountered clinical manifestations are weakness, myalgia and tea-colored urine, and the most sensitive laboratory finding of muscle injury is an elevated plasma creatine kinase level. The management of patients with rhabdomyolysis includes early vigorous hydration, together with specific measures (urine alkalinization, mannitol, hemodialysis).

Diagnosis of hypokalemia: a problem-solving approach to clinical cases

In situations where the cause of hypokalemia is not obvious, measurement of urinary potassium excretion and blood pressure and assessment of acid-base balance are often helpful. A random urine potassium-creatinine ratio (K/C) less than 1.5 suggests poor intake, gastrointestinal losses, or a shift of potassium into cells. If hypokalemia is associated with paralysis, we should consider hyperthyroidism, familial or sporadic periodic paralysis. Metabolic acidosis with a urine K/C ratio less than 1.5 suggests lower gastrointestinal losses due to diarrhea or laxative abuse. Metabolic acidosis with K/C ratio of 1.5 higher is often due to diabetic ketoacidosis or type 1 or type 2 distal renal tubular acidosis. Metabolic alkalosis with a K/C ratio less than 1.5 and a normal blood pressure is often due to surreptitious vomiting. Metabolic alkalosis with a higher K/C ratio and a normal blood pressure suggests diuretic use, Bartter syndrome, or Gitelman syndrome. Metabolic alkalosis with a high urine K/C ratio and hypertension suggests primary hyperaldosteronism, Cushing syndrome, congenital adrenal hyperplasia, renal artery stenosis, apparent mineralocorticoid excess, or Liddle syndrome. Hypomagnesemia can lead to increased urinary potassium losses and hypokalemia. The differential rests upon measurement of blood magnesium, aldosterone and renin levels, diuretic screen in urine, response to spironolactone and amiloride, measurement of plasma cortisol level and the urinary cortisol-cortisone ratio, and genetic testing.

Hyperlactemia can predict the prognosis of liver resection

Although hyperlactemia is known to accompany hepatic failure and metabolic acidosis, few reports examined the relationships between lactate concentrations and outcome after liver resection. We examined the ability of arterial plasma lactate concentration to predict the patient outcome after hepatectomy. The relationships of arterial lactate and base excess (BE) measured on admission to the intensive care unit (ICU) after hepatectomy to postoperative outcome were investigated in 151 consecutive patients. Lactate level was significantly higher in nonsurvivors than in survivors (P < 0.001), and in patients with postoperative complications than in those without complications (P < 0.001). Base excess was significantly reduced in nonsurvivors (P < 0.001) and in patients with postoperative complications (P = 0.004). The area under the receiver-operator curve of lactate to mortality was 0.86, whereas that of BE to the mortality was 0.82. Moderate correlation was observed between the lactate level at ICU admission and the highest total bilirubin concentration measured within 14 days after the surgery (r = 0.61), whereas the correlation between BE and bilirubin levels was lower (r = 0.35). Using multivariate analysis, the lactate level independently predicted mortality (P = 0.008) and morbidity (P = 0.013). Lactate (P < 0.001) and BE (P = 0.0068) levels both independently predicted the highest bilirubin concentration. The arterial plasma lactate concentration measured on admission to ICU seemed an excellent predictor of patient outcome after liver resection.

Regulation of bone cell function by acid–base balance

Bone growth and turnover results from the coordinated activities of two key cell types. Bone matrix is deposited and mineralised by osteoblasts and it is resorbed by osteoclasts, multinucleate cells that excavate pits on bone surfaces. It has been known since the early 20th century that systemic acidosis causes depletion of the skeleton, an effect assumed to result from physico-chemical dissolution of bone mineral. However, our own work has shown that resorption pit formation by cultured osteoclasts was absolutely dependent on extracellular acidification; these cells are inactive at pH levels above about 7·3 and show maximum stimulation at a pH of about 6·9. Bone resorption is most sensitive to changes in H+concentration at a pH of about 7·1 (which may be close to the interstitial pH in bone). In this region pH shifts of <0·05 units can cause a doubling or halving of pit formation. In whole-bone cultures, chronic HCO3-acidosis results in similar stimulations of osteoclast-mediated Ca2+release, with a negligible physico-chemical component.In vivo, severe systemic acidosis (pH change of about –0·05 to –0·20) often results from renal disease; milder chronic acidosis (pH change of about –0·02 to –0·05) can be caused by excessive protein intake, acid feeding, prolonged exercise, ageing, airway diseases or the menopause. Acidosis can also occur locally as a result of inflammation, infection, wounds, tumours or diabetic ischaemia. Cell function, including that of osteoblasts, is normally impaired by acid; the unusual stimulatory effect of acid on osteoclasts may represent a primitive ‘fail-safe’ that evolved with terrestrial vertebrates to correct systemic acidosis by ensuring release of alkaline bone mineral when the lungs and kidneys are unable to remove sufficient H+equivalent. The present results suggest that even subtle chronic acidosis could be sufficient to cause appreciable bone loss over time.

Acid-base and electrolyte abnormalities in dogs with gastrointestinal foreign bodies

Gastrointestinal foreign bodies occur commonly in dogs. The objective of the study was to describe the acid-base and electrolyte abnormalities identified in dogs with gastrointestinal foreign bodies and determine if these abnormalities are related to the site or type of foreign body present. Medical records of 138 dogs were reviewed, and information on signalment, initial venous electrolyte and acid-base values, surgical findings, relevant historical information, imaging modalities used, cost of hospital visit, intra- or postoperative complications, and survival was obtained. The site of the foreign body was recorded in 94.9% of cases and the most common site was the stomach (50%), followed by the jejunum (27.5%). The foreign bodies were linear in 36.2% of cases. The most common electrolyte and acid-base abnormalities regardless of the site or type of foreign body were hypochloremia (51.2%), metabolic alkalosis (45.2%), hypokalemia (25%), and hyponatremia (20.5%). No significant association was found between electrolyte or acid-base abnormalities and the site of foreign body. Linear, as opposed to discrete, foreign bodies were more likely to be associated with a low serum sodium concentration (odds ratio, 0.85; 95% confidence interval, 0.75-0.95). Hyperlactatemia (> 2.4 mmol/L) was seen in 40.5% of dogs. A wide variety of electrolyte and acid-base derangements are found in dogs with gastrointestinal foreign bodies. Hypochloremia and metabolic alkalosis are common in these dogs. Hypochloremic, hypokalemic metabolic alkalosis is seen with both proximal and distal gastrointestinal foreign bodies.

A comparison of traditional and quantitative analysis of acid-base and electrolyte imbalances in horses with gastrointestinal disorders

The purpose of this study was to compare traditional and quantitative approaches in analysis of the acid-base and electrolyte imbalances in horses with acute gastrointestinal disorders. Venous blood samples were collected from 115 colic horses, and from 45 control animals. Horses with colic were grouped according to the clinical diagnosis into 4 categories: obstructive, ischemic, inflammatory, and diarrheic problems. Plasma electrolytes, total protein, albumin, pH, pCO2, tCO2, HCO3-, base excess, anion gap, measured strong ion difference (SIDm), nonvolatile weak buffers (A(tot)), and strong ion gap were determined in all samples. All colic horses revealed a mild but statistically significant decrease in iCa2+ concentration. Potassium levels were mildly but significantly decreased in horses with colic, except in those within the inflammatory group. Additionally, the diarrheic group revealed a mild but significant decrease in Na+, tCa, tMg, total protein, albumin, SIDm, and A(tot). Although pH was not severely altered in any colic group, 26% of the horses in the obstructive group, 74% in the ischemic group, 87% in the inflammatory group, and 22% in the diarrheic group had a metabolic imbalance. In contrast, when using the quantitative approach, 78% of the diarrheic horses revealed a metabolic imbalance consisting mainly of a strong ion acidosis and nonvolatile buffer ion alkalosis. In conclusion, mild acid-base and electrolyte disturbances were observed in horses with gastrointestinal disorders. However, the quantitative approach should be used in these animals, especially when strong ion imbalances and hypoproteinemia are detected, so that abnormalities in acid-base status are evident.

Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness

STUDY OBJECTIVES

A severely altered level of consciousness (ALC) has been considered a contraindication to noninvasive positive pressure ventilation (NPPV). We compared the clinical outcome of patients with acute respiratory failure (ARF) due to COPD exacerbations and different degrees of ALC.

DESIGN

A 5-year case-control study with a prospective data collection.

SETTING

Respiratory Monitoring Unit.

PATIENTS

Eighty of 153 consecutive COPD patients requiring NPPV for ARF were divided into four groups, which were carefully matched for the main physiologic variables, according to the level of consciousness assessed with the Kelly-Matthay Score, in which 1 is normal (control subjects) and 6 is severely impaired.

MEASUREMENT AND RESULTS

Changes from baseline in arterial blood gas (ABG) levels and Kelly score, the rate and causes of NPPV failure, the rate of nosocomial pneumonia, and the 90-day mortality rate were compared. NPPV significantly improved ABG levels and Kelly score in all groups after 1 to 2 h. NPPV failure (Kelly score 1 = 15%; Kelly score 2 = 25%; Kelly score 3 = 30%; Kelly score > 3 = 45%) and 90-day mortality rate (Kelly score 1 = 20%; Kelly score 2 = 35%; Kelly score 3 = 35%; Kelly score > 3 = 50%) significantly increased with the worsening of the level of consciousness. Using a multivariate analysis, the acute nonrespiratory component of the acute physiology and chronic health evaluation (APACHE) III score, and baseline pH independently predicted baseline Kelly score. After 1 to 2 h of NPPV, changes in the Kelly score were associated with those in pH. No correlation was found with Pa(CO2).

CONCLUSIONS

This study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, whereas the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, even though better than expected, so that an initial and cautious attempt with NPPV may be performed even in this latter group. Changes in the level of consciousness induced by NPPV are not correlated with those in Pa(CO2).

Experimental study on the role of endotoxin in the development of hepatopulmonary syndrome

AIM: To evaluate the role of intestinal endotoxemia in the genesis of hepatopulmonary syndrome.

METHODS: A rat model of cirrhosis was prepared with the method of compound factors. At the end of the eighth week, rats with cirrhosis were treated with 300 μg LPS/100 g body weight, and 1 g/rat of glycine about four h prior to LPS. After three h of LPS treatment, blood and tissues were collected for various measurements. Kupffer cells were isolated from male Wistar rats and cultured, and divided into five groups. Supernatant was harvested at 3 h after treatment with LPS for measurement of tumor necrosis factor-alpha (TNF-α).

RESULTS: Our results showed that in rats with cirrhosis, slowed and deepened breath with occasional pause was. PaO₂, PaCO₂ and standard bicarbonate (SB) in arterial blood were decreased. Arterial O₂ and actual bicarbonate (AB) were markedly decreased. There was a close correlation between decreased O₂ and endotoxin. Metabolic acidosis accompanying respiratory alkalosis was the primary type of acid-base imbalance. The alveolar-arterial oxygen gradient was sharply widened. Massive accumulation of giant macrophages in the alveolar spaces and its wall and widened alveolar wall architecture were observed. The number of bacterial translocations in mesenteric lymph nodes increased. The ratio of TC99M-MAA brain-over-lung radioactivity rose. Endotoxin, and TNF-α, endothelin-1 (ET-1), nitric oxide (NO) in plasma and ET-1, carbon monoxide (CO) in lung homogenates increased. After administration of a given dosage of LPS in rats with cirrhosis, various pathological parameters worsened. Plasma level of endotoxin was related to TNF-α, ET-1, NO in plasma and ET-1, NO, CO in lung homogenates. TNF-α level was related to ET-1 and NO in plasma and lung homogenates and CO in lung homogenate as well. The level of TNF-α increased after infusion of LPS into culture supernatant of Kupffer cells in vitro. However, TNF-α significantly decreased after pretreatment with glycine, PD98059 and SB212850. Glycine could antagonize the effect of LPS in vivo and in vitro.

CONCLUSION: Intestinal endotoxemia accompanying by cirrhosis may be an important mechanism in the development of hepatopulmonary syndrome in rats. Overproduction of TNF-α due to endotoxin stimulation of Kupffer cells via mitogen-activated protein kinase (MAPK) signal transduction pathway may be a major mechanism mediating the pathologic alterations of hepatopulmonary syndrome.

Acid–base balance may influence risk for insulin resistance syndrome by modulating cortisol output

Frank metabolic acidosis is known to promote renal excretion of hydrogen ion by induction of glutaminase and other enzymes in the renal tubules. This induction, at least in part, reflects an increase in pituitary output of ACTH and a consequent increased production of cortisol and aldosterone; these latter hormones act on the renal tubules to promote generation of ammonia, which expedites renal acid excretion. Recent evidence suggests that the moderate metabolic acidosis associated with a protein-rich diet low in organic potassium salts - quantifiable by net acid output in daily urine - can likewise evoke a modest increase in cortisol production. Since cortisol promotes development of visceral obesity, and has a direct negative impact on insulin function throughout the body, even a modest sustained up-regulation of cortisol production may have the potential to increase risk for insulin resistance syndrome and type 2 diabetes. This thesis appears to be consistent with previous epidemiological reports correlating high potassium consumption, or a high intake of fruits and vegetables, with reduced risk for diabetes and coronary disease. Future prospective epidemiology should assess whether the estimated acid-base balance of habitual diets - calculated from the ratio of dietary protein and potassium - correlates with risk for insulin resistance syndrome and diabetes.

[Nephrocalcinosis]

Nephrocalcinosis is used to describe renal parenchymal calcification. Causes of nephrocalcinosis include persistent hypercalcemia, hypercalciuria, acid-base disorders, hyperoxaluria and urinary stasis. Patients with nephrocalcinosis initially present no symptom. However, advanced nephrocalcinosis is irreversible and causes impaired renal function. Therefore, careful observation for the presence and progression of nephrocalcinosis is necessary for patients who have risk factors for this disorder.

Experimental animal models of muscle pain and analgesia

Muscle pain is a prevalent clinical problem but can be difficult to treat because relatively little is known about nervous system mechanisms that mediate and modulate it. This review profiles four new animal models of muscle and deep tissue pain currently being used to elucidate mechanisms of muscle pain and analgesia.

[Anthropometric methods in evaluation of somatic development of children with metabolic diseases]

Somatic development is determined by genetic and environmental factors. Morbidity, especially in chronic metabolic diseases, is considered as one of the environmental factors which significantly influences somatic development. Chronic diseases may affect growth by five mechanisms: nutritional factors, protein loss, chronic inflammation, tissue anoxia with acid-base disturbances and by drugs used in treatment. Somatic development assessment, especially longitudinal observations in chronic diseases, give important informations concerning the growth processes, factors affecting growth and treatment effectiveness. It also allows us to determine the moment of growth delay or catch-up growth. This paper discusses the importance and the interpretation of anthropometric measurements, which should be used in the assessment of somatic development, the dynamics of growth and the nutritional status of children with metabolic diseases.

Are resuscitation and operation justified in injured patients with extreme base deficits (less than −20)?

BACKGROUND

This study assessed the outcome of injured patients in shock with an admission base deficit of -20 or less (approximate pH <7.0) at a level 1 trauma center.

METHODS

A retrospective review was made of the trauma registry, supplemented by chart review, of all trauma patients admitted with a base deficit -20 or less from 1995 to 2002. Data collected included mechanism of injury, base deficit, Injury Severity Score(ISS), operative procedures, and outcome. Data are presented as mean +/- SD.

RESULTS

Over the study period, 110 trauma patients (88% male; 31 +/- 13 years; 34% blunt trauma; ISS 26 +/- 15) were admitted with base deficit of -20 or less. Overall survival was 38%, with the majority of deaths occurring within hours of admission.

CONCLUSIONS

An admission base deficit of -20 or less is associated with high mortality in patients with gunshot wounds (64%) or blunt trauma (70%). The majority of patients who die will do so within hours of admission. Beyond 24 hours, the survival rates of 73% for patients with blunt trauma, 79% for those with gunshot wounds, and 90% for those with stab wounds justify continuing resuscitation and reoperations.

[Cardiac complications of anorexia nervosa]

The death rate of anorexia nervosa (AN) patients is up to 30 times greater than that of age-matched normal women. Bradycardia, hypotension and mitral valve prolapse are cardiac abnormalities that can be frequently found in AN patients. Risk of death is substantially linked to QT prolongation, which could be due to hypokalemia (binge/purging type AN) or to a starvation-derived anatomical remodelling of the heart (restricting type AN). The principal risk factors are duration of illness > 10 years, chronic hypokalemia, plasmatic albumin chronically < 3.6 g/dl and absolute QT > or = 600 ms.

Hypomagnesemia and concurrent acid-base and electrolyte abnormalities in patients with congestive heart failure

BACKGROUND

Patients with severe decompensated congestive heart failure (CHF) commonly exhibit acid-base and electrolyte disturbances mainly due to the activation of several neurohumoral mechanisms as well as to drugs regularly used in this population. Magnesium deficit is not infrequently observed in CHF patients but its pathophysiology remains less well-studied as compared with other electrolyte alterations, such as hypokalemia. However, there is evidence that early detection and correction of magnesium abnormalities could obviate potentially deleterious arrhythmogenic effects.

AIM

To assess the incidence of magnesium level disorders and analyze the underlying pathophysiological mechanisms in patients with CHF.

METHODS

Eighty-six consecutive CHF patients (NYHA class III or IV) admitted to our hospital over a period of 5 years were studied. Patients with diabetes mellitus, liver or renal failure, and chronic obstructive lung disease were excluded. All patients received conventional treatment with digoxin, diuretic agents and an angiotensin converting enzyme inhibitor. On admission, blood and urine electrolytes and renal function parameters were determined. Arterial blood gases and serum anion gap determinations were also performed.

RESULTS

Hypomagnesemia was found in 15 [n=15 (17.4%)] CHF patients. The majority of these patients also exhibited other electrolyte abnormalities, such as hypokalemia, hypocalcemia and hypophosphatemia. Inappropriate magnesiuria (fractional excretion of magnesium >4%) was evident in eight hypomagnesemic patients. A variety of associated conditions, including poor dietary intake, also favored magnesium depletion.

CONCLUSION

Magnesium deficit is a common electrolyte disorder in CHF (NYHA class III/IV) patients and several interrelated mechanisms are implicated in its pathogenesis. Clinicians' awareness of the incidence of hypomagnesemia in this population as well as its related pathophysiology could be useful for the early detection and appropriate treatment to inhibit its arrhythmogenic potential.

Acid-base imbalance and the skeleton

Humans generally consume a diet that generates metabolic acids leading to a reduction in the concentration of systemic bicarbonate and a fall in pH. In vitro experiments indicate that this metabolic acidosis causes a release of calcium from bone that initially is simply due to physicochemical dissolution of the mineral. On a more chronic basis metabolic acidosis alters bone cell function; there is an increase in osteoclastic bone resorption and a decrease in osteoblastic bone formation. Concomitant with the dissolution and resorption of the bone mineral there is buffering of the addition protons by bone leading to restoration of the systemic pH. Interestingly respiratory acidosis, caused by an increase in the partial pressure of carbon dioxide induces far less bone dissolution and resorption and the additional hydrogen ions are not buffered by bone. As we age we are less able to excrete these metabolic acids due to the normal decline in renal function. We hypothesize that a slight, but significant, metabolic acidosis leads to greater loss of bone mineral and increase potential to fracture.

Acid-base alterations in heatstroke

OBJECTIVE

To analyze the acid-base balance during heatstroke.

DESIGN

Retrospective study.

SETTING

Heatstroke Center, Makkah, Saudi Arabia.

PATIENTS

Hundred nine consecutive heatstroke patients (mean age 55 +/- 12 years) with rectal temperature from 40 to 43.4 degrees C following exposure to hot weather.

INTERVENTION

Arterial blood gases collected prospectively and analyzed using 95% confidence limits established by controlled experimental studies. Severity of heatstroke on admission assessed by Simplified Acute Physiology Score and Organ System Failure score.

RESULTS

Metabolic acidosis was the predominant acid-base change followed by respiratory alkalosis (81 and 55% of the patients, respectively). The prevalence of metabolic acidosis (but not respiratory alkalosis) was significantly associated with the degree of hyperthermia: 63, 95 and 100% at 41, 42 and 43 degrees C, respectively (p < 0.0001). Patients with metabolic acidosis had a large anion gap (24 +/- 5). Arterial partial pressure of oxygen (PaO2), systolic blood pressure and Organ System Failure score were similar with or without metabolic acidosis. Although the acute physiology score was higher in patients with, than without, metabolic acidosis (15.7 +/- 3.7 vs 9.8 +/- 4.4, p < 0.001), there was no significant difference in neurologic morbidity and mortality (7.9 vs 1.1%, 5.6 vs 0%, p = 0.776 and 0.581, respectively).

CONCLUSION

We conclude that metabolic acidosis is the predominant response in heatstroke.

Experimental Candida albicans lesions in healthy humans: dependence on skin pH

The addition of suspensions of Candida albicans cells under occlusion to the left and right forearms, buffered at 2 different pH levels (6.0 and 4.5), resulted after 24 h in unilateral or bilateral lesions in 14 of 15 volunteers. The resulting skin-surface pH was 5.7+/-0.3 and 5.1+/-0.2, respectively. The lesions were more pronounced on the arm with the higher pH in all 14 subjects who reacted. In 11 cases, reactions occurred only on the arm with the higher pH. The pH-induced results are not due to inhibited growth of C. albicans. They may be due to a pH dependence of the yeast's virulence capacity and/or a modulation of the host's defence ability. The use of skin-occlusive products (e.g. dressings, diapers and panty liners) is known to raise skin pH and is associated with skin infections of C. albicans. An acidic buffer incorporated in such products could be a preventive measure for Candida-induced skin rash.

Acidosis in chronic renal insufficiency

In this article we deal with three aspects of acidosis in patients with chronic renal insufficiency: clinical characteristics, pathophysiology, and therapeutic approach.

Twice-told tales of metabolic acidosis, glucocorticoids, and protein wasting: what do results from rats tell us about patients with kidney disease?

Much has been learned from animal studies in chronic renal failure that is germane to clinical studies because animal models parallel human responses. Such studies have affirmed that correction of metabolic acidosis has a favorable effect on protein metabolism, nitrogen balance and growth. In the presence of metabolic acidosis, catabolism is increased in uremia. Glucocorticoids are involved in accelerating protein degradation in muscle, which results in loss of lean body mass, while a low insulin level appears to play a permissive role in accelerating increased catabolism. Cellular mechanisms mediating these changes include upregulation of the ubiquitin-proteasome pathway and branched-chain ketoacid dehydrogenase enzyme activity in muscle. Many of these findings from rat studies have been confirmed in human studies and have important clinical implications because correction of metabolic acidosis improves nutritional status and blunts the associated increase in protein catabolism.

Does asphyxia cause cerebral palsy?

The incidence of cerebral palsy is 1 per 1,000, whereas the proportion caused by perinatal asphyxia is only 8% to 10%. The purpose of this article is to review the relationship between asphyxia and cerebral palsy. Only a minority of cases, those involving severe pathological fetal academia, are consistently associated with neonatal encephalopathy and an increased risk of cerebral palsy.

Kidney stones as a manifestation of hypercalcemic disorders. Hyperparathyroidism and sarcoidosis

When hypercalcemia is detected in a kidney stone formation, an intact parathyroid hormone measurement should be made. Detection of hyperparathyroidism (HPT) is important to prevent further stone episodes and to avoid the complications of high serum calcium in other organ systems. Stones in patients with HPT often contain apatite salts in addition to calcium oxalate because parathyroid excess may create a renal tubular acidosis. The calculi seen in patients with sarcoidosis, another hypercalcemic state that may cause stone formation, however, are usually pure calcium oxalate. Excess generation of 1,25-dihydroxyvitamin D results in intestinal hyperabsorption of calcium and secondary hyperoxaluria.

Clinical Implications of Perinatal Depression

The evaluation of the depressed newborn as a possible role in intrapartum asphyxia must be based on the objective findings of the fetal heart rate tracing, umbilical cord blood gas, and newborn neurologic function. Using these points as a basis for long-term followup, the following principles have been elucidated: Intrapartum asphyxia is an uncommon cause of childhood neurologic disfunction, the intrapartum insult necessary to cause long-term neurologic dysfunction is profound, and the child who does not manifest encephalopathy in the newborn period will not suffer long-term neurologic dysfunction that can be attributed to intrapartum asphyxia.

[Encrusted cystitis. Is it always alkaline?]

OBJECTIVE

To report on our series of encrusted cystopathy.

METHODS

The clinical records of 37 patients (25 males, 67%; 12 females, 33%) with a histological diagnosis of encrusted cystopathy were reviewed.

RESULTS

Only 11 patients (29.7%) met the classical criteria for alkaline encrusted cystitis. They had an initial or predisposing bladder lesion, irritative symptoms, passed calcareous material, a demonstrated or suspected urinary infection from ureolytic pathogens and alkaline urine. The remaining 26 patients (70.2%) with histologically demonstrated encrustations on the bladder wall did not meet the foregoing criteria. Fifty-seven percent of the patients had a previous history of bladder tumor resection and treatment with intravesical instillations.

CONCLUSIONS

Alkaline encrusted cystopathy is an uncommon condition. Encrusting cystopathy can develop in the absence of ureolytic pathogens or alkaline urine. The bladder lesion on which the encrusting cystopathy is established, is determinant in the subsequent evolution.

Hypoplastic left heart syndrome: duration of survival without surgical intervention

BACKGROUND

Mortality rate for heart transplantation for patients with hypoplastic left heart syndrome (HLHS) has improved, but there is a considerable wait until a suitable donor is available. Thus it is important to examine the duration of survival and risk factors for early death in patients with HLHS who did not undergo surgical intervention.

METHODS AND RESULTS

Twenty-six consecutive patients were studied retrospectively. Duration of survival and the 14 following variables were investigated: date of birth, body weight at birth, cardiothoracic ratio, ascending aorta diameter, interatrial communication size, coarctation of the aorta, tricuspid regurgitation, anatomic subtype (patency) of mitral and aortic valve, arterial blood gas findings (pH, PaO 2, SaO 2, PaCO2, base excess), and ST depression in the electrocardiogram. Twenty patients survived <60 days (group A) and 6 patients survived beyond 60 days (group B). The duration of survival (mean [SD]) was 60 (151) days overall (1 patient is currently alive at 783 days). The long-term survivors (beyond 60 days) increased significantly after 1991 (P <.05). Coarctation of the aorta was a significant risk of early death (<60 days) (P <.05). Interatrial communication size was significantly smaller in group B than in group A (P <.05). The mean pH and base excess were significantly lower in group A than in group B. The other 9 variables showed no significant difference between the 2 groups.

CONCLUSIONS

There was a significant correlation of long-term survival with stabilized ductal blood flow without coarctation of the aorta, adequate restriction of interatrial communication without severe hypoxemia, and no metabolic acidosis.

Gastrectomy osteopenia in the rat: the role of vitamin B12 deficiency and the type of reconstruction of the digestive tract

1. The mechanisms underlying gastrectomy osteopenia are not yet clear. The gastrectomy-associated cobalamin (vitamin B12) deficiency may favour osteopenia and skeletal fractures. Also, the exclusion of the duodenum from the food passage may contribute to gastrectomy osteopenia. To investigate this, rats were gastrectomized and the passage of nutrients restored either with the duodenum excluded (Roux Y) or included (Longmire). Sham-operated rats served as controls. In half of the rats in each gastrectomy group the serum B12 levels were normalized by parenteral administration of B12.2. Four months post operation, both gastrectomy groups showed a similar degree of osteopenia. There was normal bone mineralization; serum levels of parathyroid hormone were normal, but decreased for 25-hydroxyvitamin D, and elevated for 1,25-dihydroxyvitamin D; in urine there was decreased pH and excessive hyperphosphaturia.3.B12 therapy had no influence on any of the essential bone and mineral metabolic parameters.4. We conclude that osteopenia in the gastrectomized rat (i) is not due to B12 or folic acid deficiency, calcium deficiency or secondary hyperparathyroidism; (ii) is independent of the type of anatomic reconstruction of the digestive tract; (iii) appears to be related to disturbed vitamin D, phosphorus and acid-base metabolism.

Effect of locally applied drugs on the endolymphatic sac potential

In Ménière's disease, an inner ear disorder related to an endolymphatic hydrops, an alteration of the functioning of the endolymphatic sac has been proposed. The endolymphatic sac is assumed to be involved in the secretion/resorption of endolymph. The epithelial transport systems have been indirectly studied by the recording of the endolymphatic sac transepithelial potential (ESP) in control conditions and after the local injection of drugs such as diuretics that have been proposed in the treatment of Ménière's disease. The ESP was recorded, in vivo, in guinea pigs up to 150 minutes after the perisaccular injection of 5 microL of a 150 mmol/L (mM) NaCl solution containing various drugs known to inhibit ionic transport systems. The initial ESP was +8.4+/-0.3 mV (mean +/- SEM, n = 78). The basolateral injection of 5 microL of 150 mM NaCl induced an ESP decrease of 64%+/-6.0% (n = 12), 5 minutes after the end of the injection. Then ESP increased, returning to its initial value at 60 minutes and surpassing it at 120 minutes. Diuretics such as acetazolamide (10[-3] mol/L [M]), an inhibitor of carbonic anhydrase, and amiloride (10[-4] M), an inhibitor of Na channel or Na/H exchanger, decreased the ESP recovery. At variance, bumetanide (10[-6] M, 10[-4] M), the Na-K-Cl cotransport inhibitor, and chlorothiazide (10[-4] M), a Na-Cl cotransporter inhibitor, failed to alter the ESP as compared with the control group. Ouabain (10[-3] M), the Na+,K+-adenosine triphosphatase (ATPase) inhibitor, prevented the ESP recovery otherwise observed 60 minutes after the NaCl injection. Bafilomycin A1, the inhibitor of the vacuolar-type H+-ATPase, prevented the recovery of the ESP with a log-dose/effect (10[-5] M, 10[-6] M, 10[-8] M). Disulfonic acid stilbene (DIDS) (10[-4] M), an inhibitor of transporters involving HCO3-, also prevented the ESP recovery. These results suggest that the genesis of the ESP was highly dependent on acid-base transport systems including carbonic anhydrase, a vacuolar-type H+-ATPase, and an anionic transport system blocked by DIDS. Further studies are needed to confirm the alteration of the acid-base balance in this epithelium and its possible involvement in the pathogenesis of Ménière's disease.

Arterial blood gas abnormalities in patients with dizziness

Arterial blood gases were analyzed in 121 patients with dizziness. Sixty-one showed arterial blood gas abnormalities in the dizziness period. An increase in bicarbonate was seen in 57, increases in both bicarbonate and arterial carbon dioxide pressure in 8, and a low arterial oxygen pressure in 22 patients. The frequency of the abnormalities was significantly higher in those with central-peripheral diseases than in those with Meniere's disease. Arterial blood gases were also checked at random in the remission period in 22 patients. The frequency of dizziness recurrence was significantly higher in patients with the abnormalities in the remission period than in patients without them. These results indicate that approximately half of the patients with dizziness tend to have arterial blood gas abnormalities in the dizziness period. It is suggested that arterial blood gas abnormalities cause temporary vestibular dehabituation that increases the frequency of dizziness in central-peripheral diseases and Meniere's disease.

Can asphyxiated infants at risk for neonatal seizures be rapidly identified by current high-risk markers?

OBJECTIVE

Markers currently used to identify infants at highest risk for perinatal hypoxic-ischemic cerebral injury are insensitive in predicting the subsequent occurrence of neonatal seizures and/or neurodevelopmental sequelae, ie, cerebral palsy. To facilitate therapeutic strategies, early identification of the infant at highest risk for developing seizures secondary to hypoxia ischemia or asphyxia is critical, particularly if novel but potentially toxic therapies currently under experimental investigation become available for clinical use.

METHODS

Ninety-six inborn term infants considered at high risk for having neonatal seizures secondary to hypoxia ischemia or asphyxia and admitted to the neonatal intensive care unit directly after labor and delivery were prospectively evaluated. Markers of high risk included the presence of moderate to thick meconium-stained amniotic fluid (MSAF), fetal heart rate (FHRT) abnormalities abruptio placentae, intubation and positive pressure ventilation in the delivery room (DR), chest compressions and epinephrine administration as part of resuscitation, a 5-minute Apgar score of 5 or less, umbilical cord arterial pH of 7.00 or less, and/or a base deficit of -14 mEq/L or more negative.

RESULTS

Seizures developed in 5 (5.2%) of the 96 infants. High-risk markers included FHRT abnormalities only (n=36), FHRT abnormalities and MSAF (n=20), MSAF only (n=23), abruptio placentae (n=6), intubation in the DR (n=44), intubation in the neonatal intensive care unit (n=22), chest compressions (n=2), 5-minute Apgar scores of 5 or less (n=21), umbilical cord arterial pH of 7.00 or less (n=21), and base deficits of -14 mEq/L or more negative (n=19). By univariate analysis, significant relationships with seizures were found with Apgar scores, the need for intubation in the DR, umbilical cord arterial pH, and base deficit. Combinations of the identified risk markers showed a strong relationship with seizures with the following odds rations (ORs), 95% confidence limits, sensitivity, specificity, and positive predictive values (PPVs): (1) low cord pH and intubation, OR, 163 (confidence limits, 7.9 and 3343.7); sensitivity, 100%; specificity 94%; and PPV, 50%; (2) low cord pH and low 5-minute Apgar score, OR, 39 (confidence limits, 3.9 and 392.5); sensitivity, 80%; specificity, 91%; and PPV, 33.3%; and (3) low pH, intubation, and low 5-minute Apgar score, OR, 340 (confidence limits, 17.8 and 6480.6); sensitivity, 80%; specificity, 98.8%; and PPV, 80%.

CONCLUSIONS

A combination of high-risk postnatal markers, specifically, a low 5-minute Apgar score and intubation in the DR in association with severe fetal acidemia, facilitates the identification within the first hour of life of term infants at highest risk for developing seizures secondary to perinatal asphyxia.

Amniotic fluid meconium: a fetal environmental hazard

OBJECTIVE

To investigate the hypothesis that meconium aspiration syndrome, the major hazard of meconium during labor, may be associated with superimposed fetal acute acidemia.

METHODS

Umbilical artery blood gases were measured in 7816 term pregnancies with meconium in the amniotic fluid (AF) and the results were correlated with intrapartum and neonatal outcomes.

RESULTS

Sixty-nine (1%) infants developed meconium aspiration syndrome and 31 (45%) of these were in association with fetal acidemia at birth. Moreover, umbilical blood gas analysis and intrapartum events suggested that the fetal acidemia linked to meconium aspiration was an acute event rather than a long-duration process, which might be expected if meconium was itself a marker of an antecedent fetal asphyxial event.

CONCLUSION

Meconium in the AF may be a fetal environmental hazard when acidemia supervenes rather than solely a marker of preexisting fetal compromise leading to the release of meconium.

Factors affecting outcome following cardiopulmonary resuscitation

Many patients who receive cardiopulmonary resuscitation (CPR) for cardiac arrest do not survive to leave hospital. Factors associated with adverse outcomes include unwitnessed cardiac arrest in general wards, particularly at night, prolonged resuscitation, asystole, associated disorders (e.g. sepsis, malignancy, renal failure, and left ventricular dysfunction), absent pupillary responses, hypoxaemia, low PetCO2 during resuscitation, and severe acid base imbalance. Outside hospitals, cardiac arrests result in more favourable outcomes if they occur at work, and bystander CPR and early defibrillation are initiated. On admission to ICU, likely predictors of death or severe neurological disability include prolonged coma, impaired brainstem reflexes, and persistent convulsions. Experience with cerebrospinal fluid enzymes and electrophysiological measurements is limited. Multivariate scoring systems are not sufficiently reliable. The importance of hyperglycaemia, the required level of CPR training, and the appropriateness of responding to some cases, remain debatable.