Acid-base disturbances in acute asthma

Hyperlacticaemia in children with status asthmaticus. The Stewart approach

BACKGROUND

Patients with status asthmaticus (SA) frequently present with lactic acidosis (LA). Our goal is to identify the nature of this LA using the Stewart physicochemical model and to identify the independent factors associated with LA in children with SA.

METHODS

Analytical study of a retrospective cohort using a nested case-control design. Twenty-eight episodes of SA in 24 children were included. Patients admitted to a paediatric intensive care unit (PICU) for SA over a 9-year period were recruited consecutively. Data were analysed using the Stewart model and the Strong Ion Calculator. Data were analysed using descriptive statistics and regression models were fitted within the general linear model.

RESULTS

Hyperlacticaemia (Lact[mM/L] = 3.905 [95% CI = 3.018-4.792]) and acidosis (pH = 7.294 [95% CI = 7.241-7.339]) were observed in 18 episodes (15 patients; 62.5%). According to the Stewart model, acidosis was caused by a decrease in strong ion difference. Initially, pCO2 was high (pCO2[mmHg] = 45.806 [95% CI = 37.314-54.298]) but the net unmeasured ion (NUI) component was normal (NUI = -4,461 [95% CI = -3.51 to -5.412]), and neither changed significantly over the clinical course. There was no need to determine pyruvate, as the NUI was normal and the LA was type B (non-hypoxic, lactate/pyruvate < 25). We observed a correlation (P = .023) between LA and intramuscular epinephrine administered on arrival at hospital, but not between LA and the cumulative dose of nebulized salbutamol.

CONCLUSIONS

Most patients with SA presented LA. The Stewart model confirmed that LA is not hypoxic, probably due to sympathomimetic-related glycolysis.

Asthma and COPD: A Focus on β-Agonists - Past, Present and Future

Asthma has been recognised as a respiratory disorder for millennia and the focus of targeted drug development for the last 120 years. Asthma is one of the most common chronic non-communicable diseases worldwide. Chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide, is caused by exposure to tobacco smoke and other noxious particles and exerts a substantial economic and social burden. This chapter reviews the development of the treatments of asthma and COPD particularly focussing on the β-agonists, from the isolation of adrenaline, through the development of generations of short- and long-acting β-agonists. It reviews asthma death epidemics, considers the intrinsic efficacy of clinical compounds, and charts the improvement in selectivity and duration of action that has led to our current medications. Important β2-agonist compounds no longer used are considered, including some with additional properties, and how the different pharmacological properties of current β2-agonists underpin their different places in treatment guidelines. Finally, it concludes with a look forward to future developments that could improve the β-agonists still further, including extending their availability to areas of the world with less readily accessible healthcare.

Elevated blood lactate in COPD exacerbations associates with adverse clinical outcomes and signals excessive treatment with β2 -agonists

BACKGROUND AND OBJECTIVE

Raised blood lactate secondary to high dose β2 -agonist treatment has been reported in asthma exacerbations but has not been investigated during acute exacerbations of COPD (AECOPD). We explored associations of blood lactate measurements with disease outcomes and β2 -agonist treatments during AECOPD.

METHODS

Retrospective (n = 199) and prospective studies (n = 142) of patients hospitalized with AECOPD were conducted. The retrospective cohort was identified via medical records and the prospective cohort was recruited during hospitalization for AECOPD. Baseline demographics, comorbidities, β2 -agonist treatment, biochemical measurements and clinical outcomes were compared between patients with normal (≤2.0 mmol/L) versus elevated lactate (>2.0 mmol/L). Regression analyses examined associations of lactate measurements with β2 -agonist dosages.

RESULTS

Demographic data and comorbidities were similar between high versus normal lactate groups in both cohorts. The populations were elderly (mean >70 years), predominantly male (>60%) with reduced FEV1 (%) 48.2 ± 19 (prospective cohort). Lactate was elevated in approximately 50% of patients during AECOPD and not related to evidence of sepsis. In the prospective cohort, patients with high lactate had more tachypnoea, tachycardia, acidosis and hyperglycaemia (p < 0.05) and received more non-invasive ventilation (37% vs. 9.7%, p < 0.001, prospective cohort). There was a trend to longer hospitalization (6 vs. 5 days, p = 0.06, prospective cohort). Higher cumulative β2 -agonist dosages were linked to elevated lactate levels (OR 1.04, p = 0.01).

CONCLUSION

Elevated lactate during AECOPD was common, unrelated to sepsis and correlated with high cumulative doses of β2 -agonists. Raised lactate may indicate excessive β2 -agonist treatment and should now be investigated as a possible biomarker.

Immune metabolism in allergies, does it matter?-A review of immune metabolic basics and adaptations associated with the activation of innate immune cells in allergy

Type I allergies are pathological, type 2 inflammatory immune responses against otherwise harmless environmental allergens that arise from complex interactions between different types of immune cells. Activated immune cells undergo extensive changes in phenotype and function to fulfill their effector functions. Hereby, activation, differentiation, proliferation, migration, and mounting of effector responses require metabolic reprogramming. While the metabolic changes associated with activation of dendritic cells, macrophages, and T cells are extensively studied, data about the metabolic phenotypes of the other cell types critically involved in allergic responses (epithelial cells, eosinophils, basophils, mast cells, and ILC2s) are rather limited. This review briefly covers the basics of cellular energy metabolism and its connection to immune cell function. In addition, it summarizes the current state of knowledge in terms of dendritic cell and macrophage metabolism and subsequently focuses on the metabolic changes associated with activation of epithelial cells, eosinophils, basophils, mast cells, as well as ILC2s in allergy. Interestingly, the innate key cell types in allergic inflammation were reported to change their metabolic phenotype during activation, shifting to either glycolysis (epithelial cells, M1 macrophages, DCs, eosinophils, basophils, acutely activated mast cells), oxidative phosphorylation (M2 macrophages, longer term activated mast cells), or fatty acid oxidation (ILC2s). Therefore, immune metabolism is of relevance in allergic diseases and its connection to immune cell effector function needs to be considered to better understand induction and maintenance of allergic responses. Further progress in this field will likely improve both our understanding of disease pathology and enable new treatment targets/strategies.

Pathophysiology, Evaluation, and Management of Metabolic Alkalosis

Metabolic alkalosis is an increase in blood pH to >7.45 due to a primary increase in serum bicarbonate (HCO3 -). Metabolic alkalosis results from alkali accumulation or acid loss, and it is associated with a secondary increase in carbon dioxide arterial pressure (PaCO2). Metabolic alkalosis is a common acid-base disorder, especially in critically ill patients. The pathogenesis of chronic metabolic alkalosis includes two derangements, generation of metabolic alkalosis via gain of alkali or loss of acid and maintenance of metabolic alkalosis by increased tubular HCO3 - reabsorption (failure of the kidneys to excrete excess alkali). Metabolic alkalosis is the most common acid-base disorder in hospitalized patients, particularly in the surgical critical care unit. Mortality increases as pH increases.

Acid-Base Disturbances in Patients with Asthma: A Literature Review and Comments on Their Pathophysiology

Asthma is a common illness throughout the world that affects the respiratory system function, i.e., a system whose operational adequacy determines the respiratory gases exchange. It is therefore expected that acute severe asthma will be associated with respiratory acid-base disorders. In addition, the resulting hypoxemia along with the circulatory compromise due to heart–lung interactions can reduce tissue oxygenation, with a particular impact on respiratory muscles that have increased energy needs due to the increased workload. Thus, anaerobic metabolism may ensue, leading to lactic acidosis. Additionally, chronic hypocapnia in asthma can cause a compensatory drop in plasma bicarbonate concentration, resulting in non-anion gap acidosis. Indeed, studies have shown that in acute severe asthma, metabolic acid-base disorders may occur, i.e., high anion gap or non-anion gap metabolic acidosis. This review briefly presents studies that have investigated acid-base disorders in asthma, with comments on their underlying pathophysiology.

Beware of beta! A case of salbutamol-induced lactic acidosis in severe asthma

A 22-year-old woman presented with symptoms and signs consistent with acute severe asthma. After significant doses of beta-agonist, she developed a significant lactic acidosis. Significant issues arose in this patient's history with regards to purchase of medications, compliance and follow-up with respiratory service. Beta-adrenergic receptors when stimulated have been hypothesised to increase lipolysis, producing free fatty acids, which inhibit the conversion of pyruvate to coenzyme A within the Krebs cycle. Additional pyruvate is generated through stimulation of glycolysis and glycogenolysis through simultaneous catecholamine surge. This increased pyruvate load is shunted through anaerobic glycolysis, producing increased lactate. Steroid use during an asthma attack enhances the beta-2 receptor sensitivity, further potentiating lactate production. The hyperadrenergic state in this young asthmatic likely resulted in pyruvate and therefore lactate rise and thus metabolic acidosis as mentioned before. This piece highlights a physiological phenomenon that may occur in the context of iatrogenic hyperadrenergism.

Association of epilepsy and asthma: a population-based retrospective cohort study

Background

Epidemiologic data supporting the epilepsy–asthma association are insufficient. Therefore, we examined this association in this study.

Methods

By using claims data from the National Health Insurance Research Database (Taiwan), we executed a retrospective cohort analysis. Analysis 1 entailed comparing 150,827 patients diagnosed as having incident asthma during 1996–2013 with disease-free controls who were selected randomly during the same period, frequency matched in terms of age and sex. Similarly, analysis 2 entailed comparing 25,274 patients newly diagnosed as having epilepsy with sex- and age-matched controls who were selected randomly. At the end of 2013, we evaluated in analysis 1 the epilepsy incidence and risk and evaluated in analysis 2 the asthma incidence and risk. We applied Kaplan–Meier analysis to derive plots of the proportion of asthma-free seizures.

Results

In analysis 1, the asthma group exhibited a higher epilepsy incidence than did the control group (3.05 versus 2.26 per 1,000 person-years; adjusted hazard ratio: 1.39, 95% CI [1.33–1.45]). We also noted a greater risk of subsequent epilepsy in women and girls. In analysis 2, we determined that the asthma incidence between the control and epilepsy groups did not differ significantly; however, some age subgroups including children and individuals in their 30s had an increased risk. A negative association was found in adolescents. The Kaplan–Meier analysis revealed epilepsy to be positively associated with subsequent onset of asthma within seven years of epilepsy diagnosis.

Discussion

Asthma may be associated with high epilepsy risk, and epilepsy may be associated with high asthma risk among children and individuals in their 30s. Nevertheless, people with epilepsy in other age subgroups should be aware of the possibility of developing asthma within seven years of epilepsy diagnosis.

New perspectives on the regulation of type II inflammation in asthma

Asthma is a chronic inflammatory disease of the lungs which has been thought to arise as a result of inappropriately directed T helper type-2 (Th2) immune responses of the lungs to otherwise innocuous inhaled antigens. Current asthma therapeutics are directed towards the amelioration of downstream consequences of type-2 immune responses (i.e. β-agonists) or broad-spectrum immunosuppression (i.e. corticosteroids). However, few approaches to date have been focused on the primary prevention of immune deviation. Advances in molecular phenotyping reveal heterogeneity within the asthmatic population with multiple endotypes whose varying expression depends on the interplay between numerous environmental factors and the inheritance of a broad range of susceptibility genes. The most common endotype is one described as "type-2-high" (i.e. high levels of interleukin [IL]-13, eosinophilia, and periostin). The identification of multiple endotypes has provided a potential explanation for the observations that therapies directed at typical Th2 cytokines (IL-4, IL-5, and IL-13) and their receptors have often fallen short when they were tested in a diverse group of asthmatic patients without first stratifying based on disease endotype or severity. However, despite the incorporation of endotype-dependent stratification schemes into clinical trial designs, variation in drug responses are still apparent, suggesting that additional genetic/environmental factors may be contributing to the diversity in drug efficacy. Herein, we will review recent advances in our understanding of the complex pathways involved in the initiation and regulation of type-2-mediated immune responses and their modulation by host factors (genetics, metabolic status, and the microbiome). Particular consideration will be given to how this knowledge could pave the way for further refinement of disease endotypes and/or the development of novel therapeutic strategies for the treatment of asthma .

Management of Acute Exacerbation of Asthma and Chronic Obstructive Pulmonary Disease in the Emergency Department

Acute asthma and chronic obstructive pulmonary disease (COPD) exacerbations are the most common respiratory diseases requiring emergent medical evaluation and treatment. Asthma and COPD are chronic, debilitating disease processes that have been differentiated traditionally by the presence or absence of reversible airflow obstruction. Asthma and COPD exacerbations impose an enormous economic burden on the US health care budget. In daily clinical practice, it is difficult to differentiate these 2 obstructive processes based on their symptoms, and on their nearly identical acute treatment strategies; major differences are important when discussing anatomic sites involved, long-term prognosis, and the nature of inflammatory markers.

Advances in acute asthma

PURPOSE OF REVIEW

The purpose of this study is to highlight some of the recent findings related with the management of acute exacerbations in the context of the emergency department setting.

RECENT FINDINGS

β₂-agonist heliox-driven nebulization significantly increased by 17% [95% confidence interval (CI) 5.2-29.4] peak expiratory flow, and decreased the rate of hospital admissions (risk ratio 0.77, 95% CI 0.62-0.98), compared with oxygen-driven nebulization. Other findings indicate that there is no robust evidence to support the use of intravenous or nebulized magnesium sulphate in adults with severe acute asthma, and that levalbuterol was not superior to albuterol regarding efficacy and safety in individuals with acute asthma. Finally, hyperlactatemia developed during the first hours of acute asthma treatment has a high prevalence, is related with the use of β₂-agonists and had no clinical consequences.

SUMMARY

After a comprehensive review of the best quality pieces of literature published in the last year, it is possible to conclude that the goals of acute asthma management remain almost unchanged.

Transient occult cardiotoxicity in children receiving continuous beta-agonist therapy

BACKGROUND

Continuous beta-agonist therapy, typically in the form of inhaled albuterol, is the first line therapy for the treatment of acute and severe bronchospasm in children. Although this treatment is commonly used, concerns about cardiotoxicity have been raised. We aimed to investigate the cardiotoxic effects of continuous beta-agonist therapy in children.

METHODS

We conducted a retrospective review of children admitted to the intensive care unit (ICU) between May 2008 and April 2009, who were treated with continuous beta-agonist therapy (intravenous and nebulized).

RESULTS

Twenty of the 36 children treated with continuous albuterol had repeated serum troponin-T and lactate levels measured. Eleven patients (55%) were also treated with continuous intravenous terbutaline. Elevated levels of troponin-T levels were found in 25% of children, and elevated lactate levels were found in 60%. However, all returned to normal levels within 48 hours of ICU admission, despite continued beta-agonist therapy. No children experienced arrhythmias during therapy. There was no association between intravenous terbutaline use and elevated troponin-T [odds ratio (OR), 1.3; 95% CI, 0.2-10.3] or with elevated serum lactate (OR, 0.6; 95% CI, 0.1-3.7). There was also no association between elevated troponin-T or lactate and ICU or hospital length of stay.

CONCLUSIONS

In this small study, a significant proportion of children had elevated serum troponin-T and lactate levels while receiving inhaled continuous beta-agonist therapy, irrespective of intravenous therapy. However, these abnormal values all returned to normal within 48 hours of ICU admission and were not associated with increased duration of hospitalization.

Albuterol administration is commonly associated with increases in serum lactate in patients with asthma treated for acute exacerbation of asthma

BACKGROUND

Controversy exists around the incidence and cause of hyperlactatemia during asthma exacerbations. We evaluated the incidence, potential causes, and adverse events of hyperlactatemia in patients with acute asthma exacerbation.

METHODS

This study was a subanalysis of subjects receiving placebo from a prospective, randomized trial evaluating an IV b -adrenergic agonist in acute asthma exacerbation. Plasma albuterol, serum lactate, and bicarbonate concentrations were measured at baseline and 1.25 h, and dyspnea score and spirometry were measured at baseline and hourly for 3 h. All subjects had a therapeutic trial comprising 5 to 15 mg nebulized albuterol, 0.5 to 1 mg nebulized ipratropium, and at least 50 mg oral prednisone or its equivalent prior to initiation of the study. Following randomization, subjects were treated with continued albuterol and IV magnesium at the discretion of their treating physician. Subjects were followed to hospital admission or discharge with follow-up at 24 h and 1 week.

RESULTS

One hundred seventy-fi ve subjects were enrolled in the parent trial, with 84 in the placebo group. Sixty-fi ve had complete data. Mean SD albuterol administration prior to baseline was 12.3 5.3 mg. Mean baseline lactate was 18.5 8.4 mg/dL vs 26.5 11.8 mg/dL at 1.25 h ( P , .001). Forty-fi ve subjects (69.2%) had hyperlactatemia. Mean baseline bicarbonate level was 22.6 2.9 mEq/L vs 21.9 4.0 mEq/L at 1.25 h ( P 5 .11). Plasma albuterol concentration correlated with lactate concentration ( b 5 0.45, P , .001) and maintained a significant association after adjusting for asthma severity ( b 5 0.41, P 5 .001). Hyperlactatemia did not increase the risk of hospitalization or relapse ( P 5 .26) or was associated with lower FEV 1 % predicted at 3 h ( P 5 .54).

CONCLUSIONS

Plasma albuterol was significantly correlated with serum lactate concentration after adjusting for asthma severity. Hyperlactatemia was not associated with poorer pulmonary function as measured by 3-h FEV 1 % predicted or increased hospitalization or relapse at 1 week.

Critical Asthma Syndrome in the ICU

Critical asthma syndrome represents the most severe subset of asthma exacerbations, and the critical asthma syndrome is an umbrella term for life-threatening asthma, status asthmaticus, and near-fatal asthma. According to the 2007 National Asthma Education and Prevention Program guidelines, a life-threatening asthma exacerbation is marked by an inability to speak, a reduced peak expiratory flow rate of <25 % of a patient's personal best, and a failed response to frequent bronchodilator administration and intravenous steroids. Almost all critical asthma syndrome cases require emergency care, and most cases require hospitalization, often in an intensive care unit. Among asthmatics, those with the critical asthma syndrome are difficult to manage and there is little room for error. Patients with the critical asthma syndrome are prone to complications, they utilize immense resources, and they incite anxiety in many care providers. Managing this syndrome is anything but routine, and it requires attention, alacrity, and accuracy. The specific management strategies of adults with the critical asthma syndrome in the hospital with a focus on intensive care are discussed. Topics include the initial assessment for critical illness, initial ventilation management, hemodynamic issues, novel diagnostic tools and interventions, and common pitfalls. We highlight the use of critical care ultrasound, and we provide practical guidelines on how to manage deteriorating patients such as those with pneumothoraces. When standard asthma management fails, we provide experience-driven recommendations coupled with available evidence to guide the care team through advanced treatment. Though we do not discuss medications in detail, we highlight recent advances.

Inhaled β-agonist therapy and respiratory muscle fatigue as under-recognised causes of lactic acidosis

A 49-year-old man with chronic obstructive pulmonary disease (COPD) presented with significant tachypnoea, fevers, productive cough and increased work of breathing for the previous 4 days. Laboratory data showed elevated lactate of 3.2 mEq/L. Continuous inhaled ipratropium and albuterol nebuliser treatments were administered. Lactate levels increased to 5.5 and 3.9 mEq/L, at 6 and 12 h, respectively. No infectious source was found and the lactic acidosis cleared as the patient improved. The lactic acidosis was determined to be secondary to respiratory muscle fatigue and inhaled β-agonist therapy, two under-recognised causes of lactic acidosis in patients presenting with respiratory distress. Lactic acidosis is commonly used as a clinical marker for sepsis and shock, but in the absence of tissue hypoperfusion and severe hypoxia, alternative aetiologies for elevated levels should be sought to avoid unnecessary and potentially harmful medical interventions.

Acid-base patterns in acute severe asthma

BACKGROUND AND OBJECTIVES

Acid-base status in acute severe asthma (ASA) remains undefined; some studies report complete absence of metabolic acidosis, whereas others describe it as present in one fourth of patients or more. Conclusion discrepancies would therefore appear to derive from differences in assessment methodology. Only a systematic approach centering on patient clinical findings can correctly establish true acid-base disorder prevalence levels.

METHODS

This study examines acid-base patterns in ASA (314 patients), taking into account both natural history of disease and treatment, in patients free of other diseases altering acid-base status. Data were collected from patients admitted for ASA without prior history of chronic bronchitis, emphysema, kidney or liver disease, heart failure, uncontrolled diabetes mellitus or gastrointestinal illness. Informed consent was obtained for all patients, after study protocol approval by the Institutional Review Board.

RESULTS

Arterial blood gases, plasma electrolytes, lactate levels, and FEV(1) were measured on arrival. Severe airway obstruction was found with FEV(1) values of 25.6 ± 10.0%, substantial hypoxemia (PaO(2) 66.1 ± 11.9 mmHg) and increased A-a O(2) gradient (39.3 ± 12.3 mmHg) breathing room air. While respiratory alkalosis occurred in patients with better preservation of FEV1, respiratory acidosis was observed with more severe airway obstruction, as was increased lactate in the majority of patients, independent of PaO(2) and PaCO(2) levels.

CONCLUSIONS

Predominant acid-base patterns observed in ASA in this patient population included primary hypocapnia, or less frequently, primary hypercapnia. Lactic acidosis occurred in 11% of patients and presented consistently as a mixed acid-base disorder. These findings suggest lactic acidosis results from the combined effects of both ASA and medication-related sympathetic effects.

Severe acute asthma exacerbation in children: a stepwise approach for escalating therapy in a pediatric intensive care unit

OBJECTIVES

An increasing prevalence of pediatric asthma has led to increasing burdens of critical illness in children with severe acute asthma exacerbations, often leading to respiratory distress, progressive hypoxia, and respiratory failure. We review the definitions, epidemiology, pathophysiology, and clinical manifestations of severe acute asthma, with a view to developing an evidence-based, stepwise approach for escalating therapy in these patients.

METHODS

Subject headings related to asthma, status asthmaticus, critical asthma, and drug therapy were used in a MEDLINE search (1980-2012), supplemented by a manual search of personal files, references cited in the reviewed articles, and treatment algorithms developed within Le Bonheur Children's Hospital.

RESULTS

Patients with asthma require continuous monitoring of their cardiorespiratory status via noninvasive or invasive devices, with serial clinical examinations, objective scoring of asthma severity (using an objective pediatric asthma score), and appropriate diagnostic tests. All patients are treated with β-agonists, ipratropium, and steroids (intravenous preferable over oral preparations). Patients with worsening clinical status should be progressively treated with continuous β-agonists, intravenous magnesium, helium-oxygen mixtures, intravenous terbutaline and/or aminophylline, coupled with high-flow oxygen and non-invasive ventilation to limit the work of breathing, hypoxemia, and possibly hypercarbia. Sedation with low-dose ketamine (with or without benzodiazepines) infusions may allow better toleration of non-invasive ventilation and may also prepare the patient for tracheal intubation and mechanical ventilation, if indicated by a worsening clinical status.

CONCLUSIONS

Severe asthma can be a devastating illness in children, but most patients can be managed by using serial objective assessments and the stepwise clinical approach outlined herein. Following multidisciplinary education and training, this approach was successfully implemented in a tertiary-care, metropolitan children's hospital.

The critically ill asthmatic--from ICU to discharge

Status asthmaticus (SA) is defined as an acute, severe asthma exacerbation that does not respond readily to initial intensive therapy, while near-fatal asthma (NFA) refers loosely to a status asthmaticus attack that progresses to respiratory failure. The in-hospital mortality rate for all asthmatics is between 1% to 5%, but for critically ill asthmatics that require intubation the mortality rate is between 10% to 25% primarily from anoxia and cardiopulmonary arrest. Timely evaluation and treatment in the clinic, emergency room, or ultimately the intensive care unit (ICU) can prevent the morbidity and mortality associated with respiratory failure. Fatal asthma occurs from cardiopulmonary arrest, cerebral anoxia, or a complication of treatments, e.g., barotraumas, and ventilator-associated pneumonia. Mortality is highest in African-Americans, Puerto Rican-Americans, Cuban-Americans, women, and persons aged ≥ 65 years. Critical care physicians or intensivists must be skilled in managing the critically ill asthmatics with respiratory failure and knowledgeable about the few but potentially serious complications associated with mechanical ventilation. Bronchodilator and anti-inflammatory medications remain the standard therapies for managing SA and NFA patients in the ICU. NFA patients on mechanical ventilation require modes that allow for prolonged expiratory time and reverse the dynamic hyperinflation associated with the attack. Several adjuncts to mechanical ventilation, including heliox, general anesthesia, and extra-corporeal carbon dioxide removal, can be used as life-saving measures in extreme cases. Coordination of discharge and follow-up care can safely reduce the length of hospital stay and prevent future attacks of status asthmaticus.

Take my breath away: a case of lactic acidosis in an asthma exacerbation

A 36-year-old male with a history of chronic asthma presented to an emergency department with shortness of breath consistent with an asthma exacerbation. He had persistent tachypnea following inhaled bronchodilator treatment; thus, the workup and differential diagnosis were expanded. He was found to have a mixed respiratory alkalosis and metabolic acidosis with elevated serum lactate without an obvious cause and was admitted to hospital. His case was reviewed, and the lactic acidosis was thought to be caused by inhaled β2-agonist use. Emergency physicians should be aware of the potential side effects of inhaled β2-agonists as lactic acidosis may complicate clinical assessment and management of asthma exacerbations and lead to unnecessary and potentially dangerous escalations in therapy.

Analytic review: management of life-threatening asthma in adults

Asthma remains a troubling health problem despite the availability of effective treatment. A small but significant number of asthmatics experience life-threatening attacks culminating in intensive care unit admission. Standard treatment includes high dose systemic corticosteroids and inhaled bronchodilators. Patients with especially severe attacks may develop respiratory failure and need endotracheal intubation and mechanical ventilation. Severe airway obstruction may lead to dynamic hyperinflation and the possibility of hemodynamic collapse and barotrauma. Fortunately, most intubated asthmatics survive if physicians adhere to key management principles intended to avoid or minimize hyperinflation. The purpose of this review is to discuss the pathogenesis of life-threatening asthma and to provide practical guidance to promote rationale, safe, and effective management.

Outcome of children with life-threatening asthma necessitating pediatric intensive care

OBJECTIVE

To report the outcome of children with life-threatening asthma (LTA) admitted to a university Pediatric Intensive Care Unit (PICU).

METHODS

Retrospective study between October 2002 and May 2010 was carried out. Every child with LTA and bronchospasm was included.

RESULTS

30 admissions of 28 patients (13 M, 17 F) were identified which accounted for 3% of total PICU admissions (n = 1033) over the study period. The majority of patients were toddlers (median age 3.1 years). Few had past history of prematurity, lung diseases, or neuro-developmental conditions. Approximately half had previous admissions for asthma and one-forth with history of non-compliance to recommended treatment for asthma. One patient had parainfluenza virus and one had rhinovirus isolated. None of these factors were associated with need for mechanical ventilation (n = 6 admissions). Comparing with patients who did not receive mechanical ventilation, ventilated children had significantly higher PIM2 score (1.65 versus 0.4, p < 0.001), higher PCO2 levels (9.3 kPa versus 5.1 kPa, p = 0.01) and longer PICU stay (median 2.5 days versus 2 days, p = 0.03) The majority of patients received systemic corticosteroids, intravenous or inhaled bronchodilators. There was one pneumothorax but no death in this series.

CONCLUSIONS

LTA accounted for a small percentage of PICU admissions. Previous hospital admissions for asthma and history of non-compliance were common. Approximately one quarters required ventilatory supports. Regardless of the need for mechanical ventilation, all patients survived with prompt treatment.

Acute severe asthma: new approaches to assessment and treatment

The precise definition of a severe asthmatic exacerbation is an issue that presents difficulties. The term 'status asthmaticus' relates severity to outcome and has been used to define a severe asthmatic exacerbation that does not respond to and/or perilously delays the repetitive or continuous administration of short-acting inhaled beta(2)-adrenergic receptor agonists (SABA) in the emergency setting. However, a number of limitations exist concerning the quantification of unresponsiveness. Therefore, the term 'acute severe asthma' is widely used, relating severity mostly to a combination of the presenting signs and symptoms and the severity of the cardiorespiratory abnormalities observed, although it is well known that presentation does not foretell outcome. In an acute severe asthma episode, close observation plus aggressive administration of bronchodilators (SABAs plus ipratropium bromide via a nebulizer driven by oxygen) and oral or intravenous corticosteroids are necessary to arrest the progression to severe hypercapnic respiratory failure leading to a decrease in consciousness that requires intensive care unit (ICU) admission and, eventually, ventilatory support. Adjunctive therapies (intravenous magnesium sulfate and/or others) should be considered in order to avoid intubation. Management after admission to the hospital ward because of an incomplete response is similar. The decision to intubate is essentially based on clinical judgement. Although cardiac or respiratory arrest represents an absolute indication for intubation, the usual picture is that of a conscious patient struggling to breathe. Factors associated with the increased likelihood of intubation include exhaustion and fatigue despite maximal therapy, deteriorating mental status, refractory hypoxaemia, increasing hypercapnia, haemodynamic instability and impending coma or apnoea. To intubate, sedation is indicated in order to improve comfort, safety and patient-ventilator synchrony, while at the same time decrease oxygen consumption and carbon dioxide production. Benzodiazepines can be safely used for sedation of the asthmatic patient, but time to awakening after discontinuation is prolonged and difficult to predict. The most common alternative is propofol, which is attractive in patients with sudden-onset (near-fatal) asthma who may be eligible for extubation within a few hours, because it can be titrated rapidly to a deep sedation level and has rapid reversal after discontinuation; in addition, it possesses bronchodilatory properties. The addition of an opioid (fentanyl or remifentanil) administered by continuous infusion to benzodiazepines or propofol is often desirable in order to provide amnesia, sedation, analgesia and respiratory drive suppression. Acute severe asthma is characterized by severe pulmonary hyperinflation due to marked limitation of the expiratory flow. Therefore, the main objective of the initial ventilator management is 2-fold: to ensure adequate gas exchange and to prevent further hyperinflation and ventilator-associated lung injury. This may require hypoventilation of the patient and higher arterial carbon dioxide (PaCO(2)) levels and a more acidic pH. This does not apply to asthmatic patients intubated for cardiac or respiratory arrest. In this setting the post-anoxic brain oedema might demand more careful management of PaCO(2) levels to prevent further elevation of intracranial pressure and subsequent complications. Monitoring lung mechanics is of paramount importance for the safe ventilation of patients with status asthmaticus. The first line of specific pharmacological therapy in ventilated asthmatic patients remains bronchodilation with a SABA, typically salbutamol (albuterol). Administration techniques include nebulizers or metered-dose inhalers with spacers. Systemic corticosteroids are critical components of therapy and should be administered to all ventilated patients, although the dose of systemic corticosteroids in mechanically ventilated asthmatic patients remains controversial. Anticholinergics, inhaled corticosteroids, leukotriene receptor antagonists and methylxanthines offer little benefit, and clinical data favouring their use are lacking. In conclusion, expertise, perseverance, judicious decisions and practice of evidence-based medicine are of paramount importance for successful outcomes for patients with acute severe asthma.

Respiratory muscle strength and muscle endurance are not affected by acute metabolic acidemia

Respiratory muscle fatigue in asthma and chronic obstructive lung disease (COPD) contributes to respiratory failure with hypercapnia, and subsequent respiratory acidosis. Therapeutic induction of acute metabolic acidosis further increases the respiratory drive and, therefore, may diminish ventilatory failure and hypercapnia. On the other hand, it is known that acute metabolic acidosis can also negatively affect (respiratory) muscle function and, therefore, could lead to a deterioration of respiratory failure. Moreover, we reasoned that the impact of metabolic acidosis on respiratory muscle strength and respiratory muscle endurance could be more pronounced in COPD patients as compared to asthma patients and healthy subjects, due to already impaired respiratory muscle function. In this study, the effect of metabolic acidosis was studied on peripheral muscle strength, peripheral muscle endurance, airway resistance, and on arterial carbon dioxide tension (PaCO(2)). Acute metabolic acidosis was induced by administration of ammonium chloride (NH(4)Cl). The effect of metabolic acidosis was studied on inspiratory and expiratory muscle strength and on respiratory muscle endurance. Effects were studied in a randomized, placebo-controlled cross-over design in 15 healthy subjects (4 male; age 33.2 +/- 11.5 years; FEV(1) 108.3 +/- 16.2% predicted), 14 asthma patients (5 male; age 48.1 +/- 16.1 years; FEV(1) 101.6 +/- 15.3% predicted), and 15 moderate to severe COPD patients (9 male; age 62.8 +/- 6.8 years; FEV(1) 50.0 +/- 11.8% predicted). An acute metabolic acidemia of BE -3.1 mmol x L(-1) was induced. Acute metabolic acidemia did not significantly affect strength or endurance of respiratory and peripheral muscles, respectively. In all subjects airway resistance was significantly decreased after induction of metabolic acidemia (mean difference -0.1 kPa x sec x L(-1) [95%-CI: -0.1 - -0.02]. In COPD patients PaCO(2) was significantly lowered during metabolic acidemia (mean difference -1.73 mmHg [-3.0 - -0.08]. In healthy subjects and in asthma patients no such effect was found. Acute metabolic acidemia did not significantly decrease respiratory or peripheral muscle strength, respectively muscle endurance in nomal subjects, asthma, or COPD patients. Metabolic acidemia significantly decreased airway resistance in asthma and COPD patients, as well as in healthy subjects. Moreover, acute metabolic acidemia slightly improved blood gas values in COPD patients. The results suggest that stimulation of ventilation in respiratory failure, by induction of metabolic acidemia will not lead to deterioration of the respiratory failure.

An under-recognized complication of treatment of acute severe asthma

A 39-year-old man presented to the emergency department (ED) in severe respiratory distress. He had a prior diagnosis of brittle asthma and had been admitted on several occasions but never previously ventilated. Therapy given in the first 3 hours of arrival included nebulized salbutamol (5 mg, x5), ipratropium bromide (0.5 mg), intravenous hydrocortisone (200 mg), and magnesium sulfate (2 g). His arterial blood gases continued to deteriorate. He was then given an intravenous bolus of salbutamol (250 microg) and heliox via facemask. His worsening status necessitated invasive ventilation. His hypercapnia and resultant respiratory acidosis improved rapidly, but there was a concurrent accumulation of lactic acid resulting in acidemia. This patient had lactic acidosis as a direct effect of administration of salbutamol. The development of hazardous salbutamol-induced toxicity in acute severe asthma is discussed.

A case of lactic acidosis complicating assessment and management of asthma

Introduction

Lactic acidosis often occurs in severely unwell patients presenting to Accident and Emergency. It is commonly associated with either hypoxia or decreased tissue perfusion secondary due to cardiovascular collapse or sepsis.

Case presentation

We present a case of severe lactic acidosis in the presence of normal tissue perfusion and oxygenation in a 31-year-old patient with poorly-controlled asthma. Acidosis promptly reversed on discontinuation of inhaled beta-agonists.

Conclusion

Lactic acidosis secondary to inhaled beta-agonist administration may be a common scenario which can be misinterpreted very easily and can confuse the clinical picture. Further studies will be needed to establish the exact aetiology of this lactic acid production.

Metabolic acidosis as an underlying mechanism of respiratory distress in children with severe acute asthma

OBJECTIVE

1) To alert the clinician that increasing rate and depth of breathing during treatment of acute asthma may be a manifestation of metabolic acidosis with hyperventilation rather than worsening airway obstruction; and 2) to describe the frequency of metabolic acidosis with hyperventilation in children with severe acute asthma admitted to our pediatric intensive care unit.

DESIGN

Retrospective medical record review.

SETTING

University-affiliated children's hospital.

PATIENTS

All patients admitted to the pediatric intensive care unit with a diagnosis of asthma between January 1, 2005, and December 31, 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Fifty-three patients with asthma (median age 7.8 yrs, range 0.7-17.9 yrs; 35 [66%] male; 46 [87%] black and 7 [13%] white) were admitted to the pediatric intensive care unit during the study period. Fifteen (28%) patients developed metabolic acidosis with hyperventilation (pH <7.35, Pco2 <35 torr [4.6 kPa], and base excess < or = -7 mmol/L) during their hospital course. Of these, lactic acid was assessed in four patients and was elevated in each; all had hyperglycemia (blood glucose >120 mg/dL [6.7 mmol/L]). Patients who developed metabolic acidosis with hyperventilation received asthma therapy similar to that received by patients who did not develop the disorder. Metabolic acidosis resolved contemporaneously with tapering of beta2-adrenergic agonists and administration of supportive care. All patients survived.

CONCLUSIONS

Metabolic acidosis with hyperventilation manifesting as respiratory distress can occur in children with severe acute asthma. A pathophysiologic rationale exists for the contribution of beta2-adrenergic agents to the development of this acid-base disorder. Failure to recognize metabolic acidosis as the underlying mechanism of respiratory distress may lead to inappropriate intensification of bronchodilator therapy. Supportive care and tapering of beta2-adrenergic agents are recommended to resolve this condition.

Lactic acidosis in children with acute exacerbation of severe asthma

This is a retrospective case series reporting lactic acidosis in four pediatric patients with acute severe asthma treated with nebulized beta2-agonists in a pediatric intensive care unit of a tertiary care teaching facility. During treatment with beta2-agonists, these patients developed lactic acidosis with a peak concentration of 5.2 to 13 mmol/l. Lactic acidosis improved within 24 h after discontinuation or decrease in the dosage of beta2-agonists. We conclude that the intensive use of beta2-agonists for acute severe asthma in children may be the primary and significant cause of lactic acidosis.

Mechanisms by which systemic salbutamol increases ventilation

BACKGROUND AND OBJECTIVE

Salbutamol (SAL) has systemic effects that may adversely influence ventilation in asthmatic patients. The authors sought to determine the magnitude of this effect and mechanisms by which i.v. SAL affects ventilation.

METHODS

A prospective study of nine healthy subjects (eight men, one woman; age 23 +/- 1.4 years (SD)) was undertaken. Each subject received i.v. SAL at 5, 10 and 20 microg/min each for 30 min at each dose and was observed for 1 h post infusion. Minute ventilation ((VE)), oxygen consumption (VO(2)), CO(2) production (VCO(2)), occlusion pressure (P(0.1)), heart rate, blood pressure, respiratory rate, glucose, arterial blood gases, lactate and potassium (K(+)) were recorded at baseline and at 30-min intervals. The effect of 100% oxygen on (VE) and P(0.1) during SAL infusion at 20 microg/min was observed. Results are expressed as mean +/- SEM.

RESULTS

V(E) was significantly increased at 20 microg/min SAL (37.8 +/- 12.1%, P = 0.01), as were VO(2) (22.5 +/- 5.1%, P < 0.01) and VCO(2) (40.9 +/- 10.6%, P < 0.01). Ventilation was in excess of metabolic needs as demonstrated by a rise in the respiratory exchange ratio (0.87 +/- 0.03 to 0.99 +/- 0.04, P < 0.05). Serum lactate rose by 124 +/- 30.4% from baseline to 20 microg/min (1.1 +/- 0.1 to 2.3 +/- 0.25 mmol/L, P < 0.01) and base excess decreased (0.89 +/- 0.56 to vs. -1.75 +/- 0.52 mmol/L, P < 0.01) consistent with a lactic acidosis contributing to the excess ventilation. There was no significant differences in (VE) or P(0.1) with F(I)O(2) = 1.0, suggesting peripheral chemoreceptor stimulation was not responsible for the rise in (VE). At 20 microg/min SAL, K(+) fell significantly from baseline (3.8 +/- 0.06 to 2.8 +/- 0.09 mmol/L, P < 0.001).

CONCLUSION

Systemic SAL imposes ventilatory demands by increasing metabolic rate and serum lactate. This may adversely affect patients with severe asthma with limited ventilatory reserve.

Elevated plasma lactate level associated with high dose inhaled albuterol therapy in acute severe asthma

BACKGROUND

Lactic acidosis is a recognised event in adult patients with status asthmaticus, particularly in the setting of intensive care. However, it has been infrequently studied in patients attending the emergency departments (ED).

METHODS

We conducted a prospective and descriptive study to assess levels of lactate and effects on bronchodilator response in adult patients with acute severe asthma treated with high doses of albuterol in the ED. In total, 18 subjects (mean (SD) age 42.9 (2.7) years, FEV1 = 32.2 (10.9)% of predicted) who presented to an emergency department were enrolled in the study. All patients were treated with albuterol; four puffs (100 microg/puff) at 10 minute intervals, delivered by a pressurised metered dose inhaler into a spacer device over a 2 hour period.

RESULTS

At the end of treatment, mean (SD) plasma lactate level (2.94 (2.1) mmol/l) was significantly higher (p = 0.001) than baseline. Of the 18 patients, nine (50%) showed lactate levels > or = 2.5 mmol/l (four patients presented values > 4 mmol/l); these patients had a shorter duration of attack prior to ED presentation (p = 0.01), a higher pretreatment heart rate (p = 0.005), a lower pretreatment SpO2 (p = 0.03), a lower pretreatment PO2 (p = 0.009), a higher pretreatment PCO2, and a lower pretreatment serum potassium (p = 0.005). However, there were no significant differences in the airway response between groups.

CONCLUSIONS

This study confirmed previous observations that high lactate concentrations can develop during the first hours of inhaled beta agonist treatment. The presence of a previous hyperadrenergic state may predispose to the development of this condition. A significant improvement in lung function was associated with elevated lactate levels.

Life-threatening asthma in children: treatment with sodium bicarbonate reduces PCO2

OBJECTIVES

To assess the effect of administration of sodium bicarbonate on carbon dioxide levels in children with life-threatening asthma (LTA) and to evaluate the clinical effect of this treatment.

STUDY DESIGN

Retrospective study.

SETTING

A pediatric ICU (PICU) of a tertiary care university hospital.

PATIENTS

Seventeen children with LTA who received sodium bicarbonate.

MEASUREMENTS AND RESULTS

In January 1999, a new protocol for the treatment of LTA was initiated in our institution, incorporating the use of IV sodium bicarbonate in acidotic patients (pH < 7.15) with refractory status asthmaticus. Since January 1999, sodium bicarbonate was administered to 17 patients; 5 patients received two or three doses of sodium bicarbonate. In three patients, sodium bicarbonate was administered after intubation. Intubation and mechanical ventilation were performed in five patients before admission to the PICU, and in one patient during admission. There was a significant decrease of Pco(2) after sodium bicarbonate infusion (p = 0.007). An improvement of respiratory distress in all but one patient was seen as well.

CONCLUSIONS

Administration of sodium bicarbonate in 17 children with LTA was associated with a significant decrease in Pco(2) and an improvement of respiratory distress. The possible benefits of sodium bicarbonate in LTA deserve further study in a controlled, prospective design.

Severe exacerbations of asthma

All asthmatics regardless of their perceived severity, are at risk of exacerbation, particularly if they are suboptimally treated in the outpatient arena. Fortunately most patients recover after administration of bronchodilators and anti-inflammatory medications, but preventable deaths continue to occur and refractory cases result in hospitalization and need for mechanical ventilation. We begin this article by reviewing the pathophysiology of acute exacerbations to build a foundation for the assessment of clinical status and to provide the rationale for a carefully contemplated and evidence-based therapeutic approach. We end this article with an in-depth examination of the particular problems that are encountered during mechanical ventilation and offer a strategy that helps minimize complications. In the final analysis, however, the greatest gains in the field of acute asthma will come not from its treatment but from its prevention by enhanced educational and environmental efforts and by the delivery of optimal medications at home.

Risk Factors and Prognostic Variables for Survival of Foals with Radiographic Evidence of Pulmonary Disease

The medical records of 163 neonatal foals that had thoracic radiographs taken within 48 hours of admission to a referral hospital were reviewed. The objectives of this study were (1) to identify risk factors for the development of thoracic radiographic changes and (2) to identify prognostic indicators for survival in foals with radiographic evidence of pulmonary disease. Failure of transfer of passive immunity (IgG concentration < or = 400 mg/dL) was the only risk factor for radiographic evidence of respiratory disease identified by multivariate analysis. Hypoxemic patients (PaO2 < or = 60 mm Hg) were 4.9 times more likely to reveal radiographic abnormalities in a subset of foals for which arterial blood gas results were available. Foals with a serum creatinine concentration > 1.7 mg/dL upon presentation, dyspnea, and a history of dystocia were significantly more likely to die based on the multivariate statistical outcome analysis. An anion gap > or = 20 mEq/dL was strongly associated with nonsurvival in a subset of foals with arterial blood gas results. These hematologic and biochemical variables can be readily obtained during the initial evaluation of sick foals. The presence of a high anion gap appeared to have the greatest clinical impact and may be a useful prognostic indicator in foals with radiographic evidence of respiratory disease. In contrast, the majority of physical examination variables, including evaluation of tachypnea, abnormal respiratory sounds, fever, weakness, and milk reflux from the nares, which are usually obtained during the general respiratory evaluation of foals, were unrelated to outcome.

Lactic acidosis and status asthmaticus: how common in pediatrics?

BACKGROUND

Lactic acidosis is a well described phenomenon in adult patients with severe asthma. However, this entity is rarely reported in children with status asthmaticus.

OBJECTIVE

To report our experience in a 13-year-old girl who developed lactic acidosis as a complication of status asthmaticus and to investigate the prevalence of this complication of severe asthma. We sought to determine the frequency of lactic acidosis in such patients and to review etiologies of lactic acidosis.

METHODS

1) Observations on the clinical and laboratory findings in an adolescent girl with status asthmaticus who developed lactic acidosis were recorded. 2) The medical records of 100 children and adolescents with status asthmaticus admitted to an intensive care unit were reviewed for laboratory evidence of lactic acidosis. 3) We also reviewed our own previous experience of status asthmaticus with respiratory failure.

RESULTS

Among 100 patients admitted to a pediatric intensive care unit for status asthmaticus, a single case of isolated metabolic acidosis was identified. This proved to be attributable to lactic acidosis. When records of patients with severe respiratory failure were examined, no cases of metabolic acidosis were found.

CONCLUSIONS

Although rare, lactic acidosis does occur in pediatric-aged patients during status asthmaticus. It is important that this complication be recognized and treated because acidosis may inhibit the effectiveness of bronchodilator therapy, produce electrolyte disturbances, and cause serious adverse effects on the patient's cardiovascular system.

Lactic acidosis in status asthmaticus : three cases and review of the literature

Lactic acidosis is a frequent laboratory finding in patients with severe exacerbations of asthma. The pathogenesis of lactic acidosis in asthma is not well understood, but it has been presumed, by some, to be generated by fatiguing respiratory muscles. We herein report the cases of three patients with status asthmaticus and lactic acidosis despite pharmacologic muscle relaxation. No common etiologies were found for lactic acidosis that abated after bronchospasm improved and the intensity of pharmacologic therapies was reduced. We review the literature describing lactic acidosis with asthma and discuss mechanisms by which lactic acidosis may occur in patients with status asthmaticus.

Acute asthma

OBJECTIVE: Asthma is the most common medical emergency in children. It is associated with significant morbidity and mortality rates and poses a tremendous societal burden worldwide. Management of the acute attack involves a stepwise approach that includes beta-agonist and steroid therapy, the mainstay of emergency treatment. Most patients will respond to this regime and can be discharged from the emergency department. Failure to respond to treatment necessitates hospital admission and sometimes admission to the intensive care unit (ICU). Management in the ICU involves intensification of pharmacologic therapy, including nonstandard therapies, in an attempt to avoid intubation and ventilation. When needed, mechanical ventilatory support can be rendered fairly safe with little morbidity if the likely cardiorespiratory physiologic derangements are appreciated and if appropriate ventilatory strategies are used. In the past two decades, the availability of newer potent medications and changes in approach to monitoring and ventilatory strategies have resulted in a decrease in ICU morbidity and mortality rates. Research endeavors are presently underway to further characterize the underlying mechanisms of the disease and are likely to lead to novel therapies. This article reviews the approach to management of acute severe asthma.

Management of the severe asthmatic

Asthma morbidity and mortality continue to increase. The clinical characteristics of the high risk asthmatic patient continue to be elucidated. These include historical features, current disease characteristics and psychosocial factors. Beta-Adrenergic agonists continue to be the mainstay of acute therapy. The following review details these topics.

Hyperlactatemia during acute severe asthma

OBJECTIVE

To evaluate arterial lactate levels during treatment of acute severe asthma (ASA) and the prognostic value of arterial hyperlactatemia in ASA.

DESIGN

Prospective study.

SETTING

A respiratory intensive care unit (ICU) of a university hospital.

PATIENTS

29 consecutive patients admitted to the ICU for ASA not intubated on admission and with a peak expiratory flow (PEF) < 150 l/min or an arterial carbondioxide tension (PaCO2) > 40 mm Hg. All patients received standardized treatment during the first 24 h including i.v. and nebulized salbutamol, i.v. theophylline, and dexamethasone.

MEASUREMENTS AND RESULTS

Arterial lactate levels were serially measured by an enzymatic method during the first 24 h following admission. On admission, the mean arterial lactate level was 3.1 +/- 0.38 mmol/l (range 1.1-10.4); 17 patients (59%) had arterial hyperlactatemia with a lactate level > 2 mmol/l. No difference was found in lactate levels between patients with progressively worsening asthma and those with an acute onset of severe asthma. No correlation was found between arterial lactate levels on admission, on the one hand, and respiratory rate (RR), heart rate, PEF, pH, PaCO2, arterial oxygen tension, potassium, phosphorus, creatine kinase, or transaminase values on admission, on the other hand. All patients developed an important but transient increase in arterial lactate levels during treatment, with a peak at 7.72 +/- 0.46 mmol/l and a mean elevation of 4.62 +/- 0.45 mmol/l (range 0.4-12.1), from the initial admission value contrasting with a significant clinical improvement assessed by RR, PEF, and arterial blood gas parameters.

CONCLUSION

This study suggests that, in ASA, arterial hyperlactatemia is frequently present on admission to the ICU. Delayed hyperlactatemia is a constant finding during treatment of ASA. Initial or delayed hyperlactatemia seems of no prognostic value because none of the patients required mechanical ventilation. The effects of therapy for acute asthma on lactate metabolism still need to be studied.

Lactic acidosis secondary to severe anemia in a patient with paroxysmal nocturnal hemoglobinuria

A patient with paroxysmal nocturnal hemoglobinuria developed lactic acidosis associated with severe anemia. The lactic acidosis corrected after blood transfusion. In the absence of shock, sepsis, or other identifiable causes of lactic acidosis, the severe anemia (hemoglobin 1.2 g/dl) appeared to be the primary etiologic factor.