Metabolic alkalosis contributes to acute hypercapnic respiratory failure in adult cystic fibrosis

BACKGROUND

and study objectives: Patients with end-stage cystic fibrosis (CF) develop respiratory failure and hypercapnia. In contrast to COPD patients, altered electrolyte transport and malnutrition in CF patients may predispose them to metabolic alkalosis and, therefore, may contribute to hypercapnia. The aim of this study was to determine the prevalence of metabolic alkalosis in adults with hypercapnic respiratory failure in the setting of acute exacerbations of CF compared with COPD.

DESIGN

Levels of arterial blood gases, plasma electrolytes, and serum albumin from 14 consecutive hypercapnic CF patients who had been admitted to the hospital with a respiratory exacerbation were compared with 49 consecutive hypercapnic patients with exacerbations of COPD. Hypercapnia was defined as a PaCO(2) of > or = 45 mm Hg.

RESULTS

Despite similar PaCO(2) values, patients in the CF group were significantly more alkalotic than were those in the COPD group (mean [+/- SD] pH, 7.43 +/- 0.03 vs 7.37 +/- 0.05, respectively; p < 0.01). A mixed respiratory acidosis and metabolic alkalosis was evident in 71% of CF patients and 22% of COPD patients (p < 0.01). The mean concentrations of plasma chloride (95.1 +/- 4.9 vs 99.8 +/- 5.2 mmol/L, respectively; p < 0.01) and sodium (136.5 +/- 2.8 vs 140.4 +/- 4.5 mmol/L, respectively; p < 0.01) were significantly lower in the CF group, and the levels of serum albumin were significantly reduced (27.4 +/- 5.8 vs 33.7 +/- 4.8 mmol/L, respectively; p < 0.01).

CONCLUSION

Metabolic alkalosis contributes to hypercapnic respiratory failure in adults with acute exacerbations of CF. This acid-base disturbance occurs in conjunction with reduced total body salt levels and hypoalbuminemia.

Metabolic alkalosis and myoclonus

This is the first case reported of vomiting-induced metabolic alkalosis associated with myoclonus. The report describes an unusual presentation of myoclonus secondary to acid-base disturbance caused by recreational drug-induced vomiting. The severe derangement of hyponatraemia, hypokalaemia, and alkalosis appears to have been reasonably well tolerated due to the gradual onset and relatively long history. The causes, mechanism, and management of metabolic alkalosis are discussed.

Pre-HD dilution acidosis, without post-HD contraction alkalosis in uremic patients

The aim of this study was to verify if the degree of pre-HD acidosis and its correction post-HD is related to body fluid expansion during the interdialytic period. Twelve uremic patients without major problems, with stable hematocrit, with regular and similar HD-session characteristics, but widely varying amounts of body fluid expansion in the interdialytic period were included. Blood samples were collected from arterial line pre- and post-HD, anaerobically in heparinized syringes, for determination of HCO3-, pH and PaCO2 (radiometer Copenhagen ABL 300 Acid-Base Laboratory), in two similar HD-sessions for each patient (12 patients, 24 HD-sessions). The percentage (%) of body weight gain in the interdialytic period was also estimated. For each patient, the mean value of parameters studied in the two HD-sessions was used for the evaluation of findings. According to mean values (+/-SD) of HCO3-, pH and PaCO2 Pre-HD (18.26+/-1.99 mmol/L, 7.31+/-0.03, 36.27+/-2.5 mmHg respectively) and post-HD (26.37+/-1.7, 7.43+/-0.03, 38.43+/-2.10 respectively) patients are acidotic pre-HD and slightly alkalemic post-HD. Correlation between the percentage (%) of interdialytic body weight gain (IBWG) and the values of HCO3-, pH and PaCO2, Pre-HD (r=-0.814, p<0.001; r=-0.931, p<0.001; r=0, 100 NS; respectively) and post-HD (r=-0.958, p<0.001; r=-0.937, p<0.001; r=-0.504 NS; respectively) indicates a significant and negative relationship of IBWG% with HCO3- and pH pre- and post-HD, but not with PCO2. In conclusion, the negative relationship of IBWG% with HCO3- and pH pre- and post-HD indicates that the body fluid expansion during the interdialytic period contributes to a dilutional acidosis pre-HD, but not to a contraction alkalosis post-HD, by the elimination of fluid during the HD-session.

Patients with thrombotic thrombocytopenic purpura commonly develop metabolic alkalosis during therapeutic plasma exchange

Thrombotic thrombocytopenic purpura (TTP) and myasthenia gravis (MG) are category I indications for therapeutic plasma exchange (TPE). This study was based on the hypothesis that the development of metabolic alkalosis during TPE is more common in TTP than in MG, based on our previous observations. In order to test it, we compared the levels of bicarbonate and potassium in both groups of patients undergoing plasmapheresis. Fifteen patients with TTP (190 procedures) and ten MG patients seen concurrently were studied. While baseline bicarbonate levels were similar among all patients, the post-procedure bicarbonate levels in TTP patients were mostly elevated with a mean +/- SD of 29.4 +/- 3.5 mEq/L, as opposed to decreased or unchanged in MG patients 26.3 +/- 3.1 mEq/L (mean +/- SD) (P = 1.4 x 10(-8)). Furthermore, alkalosis in the TTP group persisted throughout subsequent daily treatments. There was also a significant decrease between pre- and post-TPE potassium levels in TTP patients (P = 3 x 10(-21)) by paired Student's t test. Additionally, samples with levels <3.3 mEq/L were alkalotic 75% of the time. In the MG group, however, potassium was normal in 85% and 83% of the pre- and post-TPE samples, respectively. Consequently, the hypokalemia was significantly more marked in the TTP group (P = 0.0008). These data confirm that plasmapheresis commonly induces metabolic alkalosis in TTP patients, probably due to high citrate in fresh frozen plasma, the frequency of treatments, and perhaps decreased renal clearance due to disease involvement of the kidneys.

Citrate anticoagulation in continuous venovenous hemodiafiltration: a metabolic challenge

OBJECTIVE

Feasibility and safety evaluation of regional citrate anticoagulation (RCA) versus systemic heparinization for continuous venovenous hemodiafiltration.

DESIGN AND SETTING

Combined retrospective and prospective observational study performed in a secondary multidisciplinary intensive care unit of the Ospedale Civico Lugano Switzerland.

PATIENTS AND INTERVENTIONS

Twelve hemodynamically unstable patients (median APACHE II score 26, interquartile range 22-29) in whom heparin was judged to be at least temporarily contraindicated. A switch from RCA (predilution setting; same iso-osmotic replacement and dialysis fluid) to heparinization or vice versa was recommended for the final evaluation; 56 dialyzers were used for RCA (1,400 h) and 39 for heparinization (1,271 h).

MEASUREMENTS AND RESULTS

Median dialyzer life span was 24.2 h (interquartile range 17.4-42.3) for RCA and 42.5 h (20.6-69.1) for heparinization. Fluid control and dialysis quality were similar in the two groups and required no additional intervention. The risk of significant hypocalcemia and metabolic alkalosis was higher at the beginning of the RCA program and decreased with the further training of the staff. Seven bleeding episodes occurred with heparinization vs. three in RCA.

CONCLUSIONS

RCA may be a safe and useful form of anticoagulation which is more expensive than heparinization but helps to minimize bleeding risk. The risk of metabolic complications is higher at the beginning of a new RCA program. For centers lacking experienced staff we suggest reserving this technique for patients with rapid clotting of the extracorporeal circuit if treated without anticoagulation.

Predictors of alkalosis after liver transplantation

BACKGROUND

Metabolic alkalosis (MA) is common after orthotopic liver transplantation (OLT).

METHODS

The study was conducted to identify factors associated with MA after 285 OLTs. MA, defined as total carbon dioxide content of 30 mEq/L or greater, developed in 115 patients (40%) within the first 3 postoperative days.

RESULTS

By univariate analysis, patients with MA had a greater preoperative carbon dioxide content (24.4 +/- 3 versus 22.9 +/- 2.9 mEq/L; P < 0.0001) and hematocrit (35% +/- 5% versus 33% +/- 6%; P < 0.02), but lower creatinine (0.9 +/- 0.5 versus 1.2 +/- 1.2 mg/dL; P < 0.001) and blood urea nitrogen levels (15 +/- 12 versus 19 +/- 17 mg/dL; P < 0.001) compared with controls. Patients with MA were administered more citrate intraoperatively compared with controls (6.2 +/- 5.2 versus 4.5 +/- 3.6 mEq/kg of body weight; P < 0.02). Patients with MA had a lower postoperative potassium level (3.7 +/- 0.4 versus 4 +/- 0.5 mEq/L; P < 0.0001) and cumulative fluid balance (-0.66 +/- 1.87 versus +0.003 +/- 3.9 L; P < 0.007) compared with controls. By multivariate analysis, preoperative carbon dioxide content (odds ratio, 1.19; 95% confidence interval [CI], 1.08 to 1.31 per mEq/L), creatinine level (odds ratio, 0.61; 95% CI, 0.39 to 0.96 per mg/dL), intraoperative administered citrate (odds ratio, 3.35; 95% CI, 1.71 to 6.53 per 10 mEq/kg body weight), and postoperative potassium level (odds ratio, 0.32; 95% CI, 0.18 to 0.57 per mEq/L) were independently associated with MA. MA was not associated with increased hospital mortality (7.8% versus 8.2%, MA versus controls). However, patients with MA spent more time on mechanical ventilation than controls (5 +/- 0.8 versus 3 +/- 0.6 days; P < or = 0.03).

CONCLUSION

Preoperative total carbon dioxide content, renal function, intraoperative administered citrate, and postoperative potassium level are independently associated with MA after primary OLT.

Metabolic alkalosis with hypoelectrolytemia in infants with cystic fibrosis

BACKGROUND

Infants with cystic fibrosis (CF) can develop episodes of hyponatremic hypochloremic dehydration with metabolic alkalosis when they sweat excessively, which is not caused by sweating in normal infants. We investigated the incidence of the metabolic alkalosis with hypoelectrolytemia in CF infants, the possible risk factors for its occurrence and the importance of the manifestation in the diagnosis of CF.

METHODS

In order to evaluate the incidence and the risk factors for the development of this sweat-related metabolic disorder in CF, we reviewed the records of all children diagnosed as having CF before the age of 12 months in a 10-year period. Data analysis included medical history data, clinical features, biochemical parameters (blood pH, serum bicarbonate, sodium, chloride and potassium levels), sweat chloride test values, as well as genetic analysis data.

RESULTS

The prevalence of metabolic alkalosis in association with low serum electrolyte concentrations (hyponatremia, hypochloremia, and hypokalemia) in infant CF population in our region was 16.5%. We found no season predilection in its occurrence. Early infant age, breast-feeding, delayed CF diagnosis, heat exhaustion and the presence of severe CF transmembrane conductance regulator mutations are predisposed factors for the development of metabolic alkalosis with hypoelectrolytemia.

CONCLUSIONS

The results from our study suggest that metabolic alkalosis with hypoelectrolytemia is a relatively common manifestation of CF in infancy. The possibility of CF should be seriously considered in any infant with this metabolic disorder.

Hypercalcaemia and metabolic alkalosis with betel nut chewing: emphasis on its integrative pathophysiology

BACKGROUND

Events in the gastrointestinal tract that might contribute to a high absorption of calcium were simulated in vitro to evaluate why only a small proportion of individuals who ingest alkaline calcium salts develop hypercalcaemia, hypokalaemia and metabolic alkalosis.

METHODS

A patient who chewed and swallowed around 40 betel nuts daily developed hypercalcaemia, metabolic alkalosis, hypokalaemia with renal potassium wasting, and renal insufficiency. The quantities of calcium and alkali per betel nut preparation were measured. Factors that might increase intestinal absorption of calcium were evaluated.

RESULTS

Hypercalcaemia in the index case was accompanied by a high daily calcium excretion (248 mg, 6.2 mmol). Circulating levels of 1,25-dihydroxyvitamin D(3) and parathyroid hormone were low. Hypokalaemia with a high transtubular K(+) concentration gradient, metabolic alkalosis, a low excretion of phosphate and a very low glomerular filtration rate were prominent features.

CONCLUSIONS

Possible explanations for the pathophysiology of metabolic alkalosis and hypokalaemia are provided. We speculate that a relatively greater availability of ionized calcium than inorganic phosphate in the lumen of the intestinal tract could have enhanced dietary calcium absorption.

[Severe metabolic alkalosis and beer drinking]

We describe a case report with moderately low plasma sodium level and predominant metabolic alkalosis. Others have reported acid-base balance disorders, although no clear pathophysiological explanation has been put forward. We hypothesize that, combine with poor protein intake, mild hyperosmolar beer leads to a water intoxication syndrome, whereas strong hyperosmolar beer intake more likely induces hypochloremic metabolic alkalosis.

Inherited primary renal tubular hypokalemic alkalosis: a review of Gitelman and Bartter syndromes

Inherited hypokalemic metabolic alkalosis, or Bartter syndrome, comprises several closely related disorders of renal tubular electrolyte transport. Recent advances in the field of molecular genetics have demonstrated that there are four genetically distinct abnormalities, which result from mutations in renal electrolyte transporters and channels. Neonatal Bartter syndrome affects neonates and is characterized by polyhydramnios, premature delivery, severe electrolyte derangements, growth retardation, and hypercalciuria leading to nephrocalcinosis. It may be caused by a mutation in the gene encoding the Na-K-2Cl cotransporter (NKCC2) or the outwardly rectifying potassium channel (ROMK), a regulator of NKCC2. Classic Bartter syndrome is due to a mutation in the gene encoding the chloride channel (CLCNKB), also a regulator of NKCC2, and typically presents in infancy or early childhood with failure to thrive. Nephrocalcinosis is typically absent despite hypercalciuria. The hypocalciuric, hypomagnesemic variant of Bartter syndrome (Gitelman syndrome), presents in early adulthood with predominantly musculoskeletal symptoms and is due to mutations in the gene encoding the Na-Cl cotransporter (NCCT). Even though our understanding of these disorders has been greatly advanced by these discoveries, the pathophysiology remains to be completely defined. Genotype-phenotype correlations among the four disorders are quite variable and continue to be studied. A comprehensive review of Bartter and Gitelman syndromes will be provided here.

[Severe metabolic alkalosis following hypokalemia from a paraneoplastic Cushing syndrome]

Metabolic alkalosis is frequently observed in critically ill patients. Etiologies are numerous but endocrinal causes are rare. We report a case of a patient with severe respiratory insufficiency, metabolic alkalosis and hypokalemia. The evolution was fatal. Further explorations revealed an ectopic Adrenocorticotropine Hormone syndrome. The initial tumor was probably a small cell lung carcinoma.

Unexpected electrolyte changes in a vomiting man

A 27 year old man presented with 24 hours of unexplained vomiting. His past health was unremarkable except for a deep vein thrombosis one year earlier. At that time his serum electrolytes were normal. The results of repeat electrolyte measurement are shown in Table 1.

Usefulness of plasma exchange plus continuous hemodiafiltration to reduce adverse effects associated with plasma exchange in patients with acute liver failure

OBJECTIVE

To efficiently remove middle-molecular-weight substances such as hepatic toxins and minimize adverse effects associated with plasma exchange implementation, we have performed plasma exchange slowly in combination with continuous hemodiafiltration. This study was designed to determine the usefulness of plasma exchange with continuous hemodiafiltration in reducing the adverse effects associated with implementation of plasma exchange alone.

DESIGN

A retrospective clinical study.

SETTING

University teaching hospital.

PATIENTS

The study involved 90 patients with liver failure who had been treated with plasma exchange in our department over the past 12 yrs. We examined these patients by dividing them into two groups (48 patients treated with plasma exchange alone and 42 patients treated with plasma exchange plus continuous hemodiafiltration at the time of plasma exchange implementation).

MEASUREMENTS AND MAIN RESULTS

Baseline blood Na+ concentration, HCO3- concentration, and colloid osmotic pressure were followed after implementation of plasma exchange to compare the frequency of development of three adverse effects (hypernatremia, metabolic alkalosis, and sharp decrease in colloid osmotic pressure) in the two groups. Hypernatremia was found in 26.7% of treatments in the group with plasma exchange alone and 3.3% in the group of plasma exchange plus continuous hemodiafiltration, and metabolic alkalosis was found in 30.6% of treatments in the group with plasma exchange alone and 4.9% in the group of plasma exchange plus continuous hemodiafiltration; both percentages were significantly higher in the group with plasma exchange alone (p <.001). A sharp decrease in colloid osmotic pressure occurred in 13.3% of treatments in the group with plasma exchange alone but was not observed at all in the patients treated with plasma exchange plus continuous hemodiafiltration.

CONCLUSIONS

We conclude that adverse effects associated with plasma exchange for artificial liver support for liver failure can be alleviated with use of plasma exchange plus continuous hemodiafiltration instead of plasma exchange alone.

Gitelman's syndrome: an overlooked cause of chronic hypokalemia and hypomagnesemia in adults

In 1966, Gitelman described a benign variant of classical Bartter's syndrome in adults characterized by consistent hypomagnesemia and hypocalciuria, hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism with normal blood pressure. A specific gene has been found responsible for this disorder, encoding the thiazide-sensitve Na-Cl coporter (TSC) in the distal convoluted tubule. Mutant alleles result in loss of normal TSC function and the phenotype is identical to patients with chronic use of thiazide diuretics. Gitelman's syndrome is a more common cause of chronic hypokalemia than Bartter's syndrome, with which it is often confused. The distinguishing features between both syndromes are discussed.