Esophageal Carcinoma

Posted by Carla Rothaus • December 26th, 2014

The 5-year survival rate in esophageal cancer, although poor, has improved over the past decade. A new review discusses the epidemiologic aspects, pathogenesis, prevention, and therapy of esophageal adenocarcinoma and squamous-cell carcinoma, focusing on recent advances.

In spite of the fact that the ability to detect early-stage esophageal adenocarcinoma has improved, most tumors are found when regional metastasis (in 30% of cases) or distant metastasis (in 40% of cases) has already occurred, at which point the 5-year survival rate declines from 39% in cases of localized disease to 4% in cases with distant metastasis.

Clinical Pearls

Describe the epidemiology of esophageal cancer.

Esophageal cancer has two main subtypes — esophageal squamous-cell carcinoma and esophageal adenocarcinoma; their precursor lesions are esophageal squamous dysplasia and Barrett’s esophagus, respectively. Although squamous-cell carcinoma accounts for about 90% of cases of esophageal cancer worldwide, the incidence of and mortality rates associated with esophageal adenocarcinoma are rising and have surpassed those of esophageal squamous-cell carcinoma in several regions in North America and Europe. In the United States, more than 18,000 new cases of esophageal cancer and more than 15,000 deaths from esophageal cancer were expected in 2014. Esophageal carcinoma is rare in young people and increases in incidence with age, peaking in the seventh and eighth decades of life. The main risk factors for esophageal adenocarcinoma are gastroesophageal reflux disease, obesity, and cigarette smoking; H. pylori infection is associated with a reduced risk. Cigarette smoking and alcohol consumption constitute the main risk factors for esophageal squamous-cell carcinoma. High intake of red meats, fats, and processed foods is associated with an increased risk of both types of esophageal cancer, whereas high intake of fiber, fresh fruit, and vegetables is associated with a lower risk.

How do esophageal adenocarcinoma and esophageal squamous-cell carcinoma differ?

Esophageal adenocarcinoma has become the predominant type of esophageal cancer in North America and Europe, while esophageal squamous-cell carcinoma remains the predominant esophageal cancer in Asia, Africa, and South America and among African Americans in North America. Adenocarcinoma is three to four times as common in men as it is in women, whereas the sex distribution is more equal for squamous-cell carcinoma. The endoscopic appearance is also similar, although approximately three quarters of all adenocarcinoma lesions are found in the distal esophagus, whereas squamous-cell carcinoma is more frequent in the proximal to middle esophagus. The overall 5-year survival rate for patients with esophageal adenocarcinoma in the United States is approximately 17%, which is slightly higher than the rate for patients with squamous-cell carcinoma.

Morning Report Questions

Q: What is the typical presentation of a patient with esophageal carcinoma?

A: The clinical presentation is similar between esophageal adenocarcinoma and squamous-cell carcinoma, despite differences in demographic and risk factors. Common clinical presentations include progressive dysphagia, weight loss, and heartburn unresponsive to medical treatment, as well as signs of blood loss. Less common symptoms include hoarseness, cough, and pneumonia related to laryngeal nerve paralysis or invasion of the tracheobronchial tree.

Q: How is adenocarcinoma of the esophagus treated?

A: The introduction of endoscopic mucosal resection with or without ablation has been a major advance in treating not only Barrett’s esophagus with high-grade dysplasia but also adenocarcinoma that is limited to the epithelial portion of the mucosa (category T1a), particularly for small tumors (<2 cm in diameter) that are asymptomatic and noncircumferential. In patients with category T1b tumors that have penetrated the muscularis mucosae and entered the submucosa, the risk of lymph-node spread is as high as 20%, and radical esophagectomy may be the preferred method of treatment, although some treatment centers have expanded the indications for endoscopic therapy to include low-risk submucosal tumors. Locally advanced tumors, defined as category T3N1, are best treated with esophagectomy. The main advance in treating patients who undergo esophagectomy has been the adoption of neoadjuvant treatment.       Randomized, controlled trials have shown a survival benefit with neoadjuvant chemoradiotherapy or chemotherapy, as compared with esophagectomy alone, in both types of esophageal carcinoma. Obstructive symptoms related to unresectable disease can be palliated with endoscopic esophageal stenting or high-dose intraluminal brachytherapy.

Figure 2. Simplified Staging of Esophageal Carcinoma.

Table 1. Management of Esophageal Adenocarcinoma.

 

Acute Traumatic Brain Injury

Posted by Carla Rothaus • December 26th, 2014

In a phase 3 trial, progesterone had no benefit as a neuroprotective agent in patients with blunt traumatic brain injury. Together with a second negative clinical trial of progesterone for acute TBI (SYNAPSE), the findings provide no support for this therapeutic approach.

More than 2.4 million emergency department visits, hospitalizations, or deaths are related to traumatic brain injury (TBI) annually, and approximately 5.3 million Americans are living with disability from TBI. The aggregate annual cost of TBI in the United States now approaches $76.5 billion. Survivors of severe TBI typically require 5 to 10 years of intensive therapy and are often left with substantial disability. Despite decades of research, no pharmacologic agent has been shown to improve outcomes after TBI.

Clinical Pearls

What is the basis for interest in the use of progesterone for acute traumatic brain injury?

Progesterone is a potent neurosteroid synthesized in the central nervous system. Preclinical studies in laboratory animals indicated that the early administration of progesterone after experimental TBI reduced cerebral edema, neuronal loss, and behavioral deficits. Enthusiasm for progesterone as a treatment for TBI was further stimulated by two single-center clinical trials showing decreased mortality and improved functional outcomes with progesterone as compared with placebo.

•What do the Extended Glasgow Outcome Scale (GOS-E) scores indicate with respect to functional outcome?

A GOS-E score of 1 indicates death, 2 indicates a vegetative state, 3 or 4 indicates severe disability, 5 or 6 indicates moderate disability, and 7 or 8 indicates good recovery.

Q: Does the early administration of progesterone (within 4 hours after injury) improve the outcome in patients with moderate-to-severe acute TBI when compared to placebo?

A: Despite extensive preclinical data and two promising single-center trials, progesterone was not associated with any benefit over placebo, as measured by the GOS-E score at 6 months, in this large, multicenter clinical trial. For the primary hypothesis comparing progesterone with placebo, favorable outcomes occurred in 51.0% of patients assigned to progesterone and in 55.5% of those assigned to placebo; the model estimated a relative benefit of 0.95 (95% confidence interval [CI], 0.85 to 1.06; P=0.35), with a relative benefit of less than 1.00 indicating fewer favorable outcomes in the progesterone group than in the placebo group.

Table 2. Outcomes at 6 Months.

Q: Was progesterone associated with more adverse events than placebo in this trial?

A: Progesterone was associated with an acceptable safety profile. Eight prospectively defined adverse events that were deemed to be potentially associated with the study drug were similar in frequency in the two groups. However, phlebitis or thrombophlebitis was significantly more frequent in the progesterone group than in the placebo group (relative risk, 3.03; 95% CI, 1.96 to 4.66). Episodes of phlebitis were frequently categorized as not serious and were self-limited.

Table 3. Adverse Events Potentially Associated with the Study Drug. 

Two New NEJM Quick Takes – Watch them Now!

Posted by Karen Buckley • December 22nd, 2014

The latest Quick Take animation, narrated by Editor-in-Chief Jeffrey Drazen, summarizes a new study that explores the efficacy of a not-so-new but largely unknown over-the-counter medication for smoking cessation. In the randomized trial of smokers who called New Zealand’s national Quitline, cytisine (a partial nicotinic acetylcholine receptor agonist) was superior to nicotine-replacement therapy in helping smokers quit. Would this less expensive treatment work elsewhere in the world? View the Quick Take on smoking cessation.  For more information, read the full article, and the Insights post on this topic.

A new Quick Take video summary gives an overview of the recently published results of the MR CLEAN trial, which found that for patients with acute ischemic stroke caused by a proximal occlusion of the anterior circulation, intra-arterial therapy administered within six hours of symptom onset can improve functional outcomes. Watch the video summary now. For more information, read the full article and accompanying editorial. And to discuss the results with the authors and experts in the field, participate in the live discussion on the new NEJM Group Open Forum.

You may also wish to peruse previous Quick Takes you may have missed.

Acute Pericarditis

Posted by Carla Rothaus • December 19th, 2014

Acute pericarditis in the United States is usually idiopathic and presumed to be viral. A history and laboratory tests, a chest radiograph, and an echocardiogram are used in evaluation. Treatment usually includes an NSAID and colchicine.  The latest Clinical Practice review, on this topic, comes from Dr. Martin LeWinter, at the University of Vermont Medical Center.

In developed countries, roughly 80 to 90% of cases of acute pericarditis are idiopathic; that is, no specific cause is identified after routine evaluation. It is assumed that these cases are viral. The remaining 10 to 20% of cases are most commonly associated with post-cardiac injury syndromes, connective-tissue diseases (especially systemic lupus erythematosus), or cancer.

Clinical Pearls

How does acute pericarditis present clinically, and what are the diagnostic criteria?

Chest pain is the presenting symptom in virtually all patients for whom a diagnosis of pericarditis would be considered. Although the differential diagnosis of chest pain is extensive, certain features point strongly to pericarditis, especially pleuritic pain that is relieved by sitting forward and that radiates to the trapezius ridge (the latter feature is virtually pathognomonic). Many patients have premonitory symptoms suggestive of a viral illness, and an abrup onset is not unusual. Sinus tachycardia and low-grade fever are also common. The diagnosis of acute pericarditis is established when a patient has at least two of the following symptoms or signs: chest pain consistent with pericarditis, pericardial friction rub, typical ECG changes, or a pericardial effusion of more than trivial size. Because the rub and ECG findings may be transient, frequent auscultation and ECG recordings can be helpful in establishing the diagnosis.

Figure 1. Typical Electrocardiogram in a Patient with Acute Pericarditis.

What is the general approach when acute pericarditis is suspected or confirmed?

Appropriate tests include a complete blood count with a differential count, a high-sensitivity test of C-reactive protein, measurements of troponin I or T and serum creatinine, and liver-function tests. A chest radiograph should always be obtained, and findings should be normal unless there is a large pericardial effusion or an associated pulmonary disorder. An echocardiogram is routinely indicated for patients with suspected or confirmed pericarditis. The most important rationale is detection of a pericardial effusion, which can cause or threaten to cause cardiac tamponade without enlarging the cardiac silhouette on a chest radiograph.

Figure 2. Suggested Initial Approach for a Patient Presenting with Chest Pain Suggestive of Acute Pericarditis.

Morning Report Questions

Q: What is the treatment for acute pericarditis?

A: Nonsteroidal antiinflammatory drugs (NSAIDs) have long been the mainstay of the initial treatment of acute pericarditis. The most commonly used agents are ibuprofen (600 to 800 mg every 6 to 8 hours), indomethacin (25 to 50 mg every 8 hours), and aspirin (2 to 4g daily in divided doses). Patients receiving these drugs should also receive a proton pump inhibitor for gastric protection. On the basis of observational data from a relatively small number of patients with recurrent pericarditis, the European Society of Cardiology concluded in its 2004 guidelines that there was sufficient evidence to recommend colchicine combined with an NSAID for initial treatment of a first bout of pericarditis. More recently, evidence from the Investigation on Colchicine for Acute Pericarditis (ICAP) randomized clinical trial, involving patients with a first episode of pericarditis, strongly supported this recommendation. The optimal duration of treatment is uncertain. For colchicine, a 3-month course is reasonable on the basis of results from the ICAP trial. The usual duration of NSAID treatment, supported by expert opinion, is 1 to 2 weeks, with the actual duration driven by clinical response.

Q: What clinical course can be expected for most patients diagnosed with acute pericarditis?

A: In 70 to 90% of patients, acute idiopathic pericarditis is self-limited, responds promptly to initial treatment, and completely resolves. In a small number of patients, probably less than 5%, the condition does not respond satisfactorily to initial treatment, and in 10 to 30% of patients, recurrences develop after a satisfactory initial response. Most patients have only one or two recurrences, but a small fraction (probably less than 5% of the total population with acute pericarditis) have multiple recurrences with considerable disability. Ultimately, recurrences cease in the majority of cases.

Smoking Cessation

Posted by Carla Rothaus • December 19th, 2014

In a trial involving smokers who called the New Zealand national quitline, cytisine (a partial agonist of the nicotinic acetylcholine receptor) was superior to nicotine-replacement therapy in helping smokers quit. Nausea and sleep disorders were more frequent with cytisine.

Four systematic reviews report cytisine to be superior to placebo for short-term and long-term smoking abstinence. No trials have compared cytisine with nicotine-replacement therapy; a pragmatic, open-label, noninferiority trial conducted in New Zealand investigated whether cytisine was at least as effective as nicotine-replacement therapy.

Clinical Pearls

What is cytisine?

Cytisine is a plant-based alkaloid found in members of the Leguminosae family. Like varenicline, cytisine is a partial agonist of nicotinic acetylcholine receptors (nAChRs), with an affinity for the alpha4beta2 receptor subtype, and a half-life of 4.8 hours. Cytisine remains relatively unknown outside Eastern Europe despite calls for licensing worldwide because of its proven benefits, low cost as compared with other cessation medications (cytisine, $20 to $30 for 25 days; nicotine-replacement therapy, $112 to $685 for 8 to 10 weeks; varenicline, $474 to $501 for 12 weeks), and low cost per quality-adjusted-life-year.

Is cytisine as effective as nicotine-replacement therapy for smoking cessation?

Cytisine was not only noninferior to nicotine-replacement therapy but had superior effectiveness: 1-month continuous abstinence rates were significantly higher in the cytisine group (40%, 264 of 655) than in the nicotine-replacement therapy group (31%, 203 of 655) (risk difference, 9.3 percentage points; 95% confidence interval [CI], 4.2 to 14.5; number needed to treat, 11). The effectiveness of cytisine for continuous abstinence was superior to that of nicotine-replacement therapy at 1 week, 2 months, and 6 months.

Table 2. Continuous Abstinence and 7-Day Point-Prevalence Abstinence According to Treatment Group, According to the Intention-to-Treat Analysis.

Morning Report Questions

Q: Is cytisine equally effective in men and women?

A: Among secondary outcomes, prespecified analyses conducted according to sex showed a significantly higher 1-month continuous abstinence rate with cytisine in women and showed no significant difference (noninferiority) in men (P=0.011 for heterogeneity). The higher quit rate observed in women taking cytisine has not been previously reported in studies of nAChR partial agonists. This finding could be the result of chance (since data were not adjusted for multiplicity) but warrants further investigation, since several reviews of nicotine-replacement therapy have reported lower quit rates in women than in men, possibly as a result of biologic and psychosocial differences.

Q: How do the safety profiles of cytisine and nicotine-replacement therapy compare?

A: Self-reported adverse events occurred more frequently in the cytisine group (288 events reported by 204 participants) than in the nicotine-replacement-therapy group (174 events reported by 134 participants), with an incidence rate ratio of 1.7 (95% CI, 1.4 to 2.0; P<0.001). The majority of adverse events were nonserious and were mild to moderate in severity. The most frequent adverse events in the cytisine group were nausea and vomiting and sleep disorders.

Table 3. Summary of All-Cause Adverse Events.

New Conversations on the NEJM Group Open Forum

Posted by Karen Buckley • December 18th, 2014

Will the results of the MR CLEAN trial change the standard of care for patients with acute ischemic stroke? Ask the authors and other experts in the field in the latest discussion about NEJM original research.

From the NEJM CareerCenter “Fascinating Physician” series, meet Dr. Wen Dombrowski, a geriatrics physician executive who develops technology, business, and collaborative health care solutions to improve the quality of life in vulnerable populations.

And the lively discussion with Dr. Julian Seifter on acid-base disorders has been extended for another week!

The NEJM Group Open Forum is publicly available for all to view, but in order to comment you must register with Medstro — a simple, one-minute process — and be a physician.

Where There’s Smoke: Cytisine versus Nicotine Replacement Therapy

Posted by Rena Xu • December 17th, 2014

Motivation, it’s often said, is half the battle of behavior change.  In the battle against nicotine addiction, however, motivation alone may not be enough.  Mass media campaigns have helped to raise awareness about the dangers of smoking.  But for the majority of smokers who already want to quit, the question remains: how?

In 2006, a drug called varenicycline — more commonly known as Chantix — entered the market.  Chantix is a partial agonist of nicotinic acetylcholine receptors; it works in part by decreasing the pleasure response to smoking.  In Eastern Europe, a related drug called cytisine has been used for smoking cessation for some time.  Cytisine has the same mechanism of action as Chantix but is sold as a generic agent and is much cheaper.  Both agents work differently from nicotine replacement therapy (e.g., gum or patches), which directly supply nicotine to the body.

A study published this week in NEJM compared the effectiveness of cytisine versus nicotine replacement therapy for smoking cessation.  1300 adult smokers in New Zealand were randomized to receive either cytisine for 25 days or nicotine replacement therapy for 8 weeks.  Participants also received behavioral support.  The primary outcome was self-reported continuous abstinence after one month.

At one month, 40% of participants in the cytisine group reported continuous abstinence, as compared to 31% of those on nicotine replacement therapy (absolute difference of 9.3 percentage points; 95% confidence interval 4.2 to 14.5; number needed to treat = 11).  Abstinence was also higher with cytisine than with nicotine replacement therapy at two and six months.  And, time to relapse (resumption of smoking) was longer for patients in the cytisine group as compared to the nicotine replacement group (53 versus 11 days; hazard ratio 0.8, P=0.001).

Not surprisingly, whether patients were compliant with therapy made a difference.  In the cytisine group, the median time to relapse was 127 days among compliant participants, versus only 20 days among those who were non-compliant (P<0.001).  Unfortunately, compliance rates weren’t great – only 53% in the cytisine group, and 67% in the nicotine replacement therapy group.

There were more self-reported adverse events with cytisine than nicotine replacement therapy, with an incidence rate ratio of 1.7 (P<0.001).  The most commonly reported events were nausea and vomiting and sleep disorders.  The authors note, “The higher proportion of adverse events in the cytisine group may be due to reporting bias, since the known side effects of nicotine-replacement therapy could have been regarded as ‘normal’ by participants in the nicotine replacement therapy group who had previously received such therapy and could therefore have gone unreported.”

Today, cytisine use is mostly limited to Eastern Europe.  Considering it is much less expensive than Chantix ($20-$30 for the recommended 25 day treatment course of cytisine versus $500 for 12 weeks of Chantix), if cytisine is indeed more effective than nicotine replacement therapy, as the findings of this study suggests, then introducing it to a broader market could yield tremendous value.

What is your current approach to smoking cessation?  What has been your experience with Chantix?  If cytisine becomes available to you, how do you anticipate it will fit into your treatment algorithm? 

For more on this topic, view the NEJM Quick Take animation, narrated by editor-in-chief Jeffrey Drazen.

Polycystic Kidney Disease

Posted by Carla Rothaus • December 11th, 2014

In patients with autosomal dominant polycystic kidney disease, the rate of increase in total kidney volume was not slowed by lisinopril and telmisartan, as compared with lisinopril and placebo, but was slowed with rigorous blood-pressure control.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by gradual cyst enlargement over a period of decades before the loss of kidney function. Hypertension occurs early and is associated with progression to end-stage renal disease (ESRD) and death from cardiovascular causes in patients with ADPKD. Immunohistologic studies and clinical studies support a central role of the renin-angiotensin-aldosterone system (RAAS) in the pathogenesis of hypertension in patients with ADPKD. It is unclear whether more aggressive antihypertensive therapy or an increased use of RAAS inhibitors delays progression to ESRD in patients with ADPKD.

Clinical Pearls

Does rigorous blood pressure control confer benefits in young patients with early ADPKD?

In the study by Schrier et al., as compared with standard blood-pressure control, rigorous blood-pressure control was associated with a slower increase in total kidney volume, no overall change in the estimated GFR, a greater decline in the left-ventricular-mass index, and greater reduction in urinary albumin excretion. Participants in the low-blood-pressure group had a 14.2% slower annual increase in total kidney volume, as compared with those in the standard-blood-pressure group (5.6% vs. 6.6%, P=0.006). Patients younger than 30 years of age with the largest kidneys were more likely to benefit from rigorous blood-pressure control than were patients of similar age with smaller kidneys. Men, but not women, also had evidence of a benefit from low blood pressure.

Figure 2. Changes in Total Kidney Volume and Estimated Glomerular Filtration Rate (eGFR) during Follow-up, and Subgroup Analyses, According to Blood-Pressure Group.

Is there a benefit to dual blockade of the RAAS in patients with autosomal dominant polycystic kidney disease?

Lisinopril-telmisartan treatment did not show a benefit, as compared with lisinopril alone, with regard to the change in total kidney volume or estimated GFR. The total kidney volume increased at similar rates in the lisinopril-telmisartan group and the lisinopril-placebo group (6.0% per year and 6.2% per year, respectively; P=0.52). Urinary albumin excretion remained unchanged in the two treatment groups. A significant and similar decline from baseline in the left-ventricular-mass index occurred in the two groups. Renal blood flow decreased and renal vascular resistance increased similarly in the two groups.

Figure 3. Changes in Total Kidney Volume and eGFR during Follow-up, and Subgroup Analyses, According to Treatment Group.

Morning Report Questions

Q: Were there significant between-group differences with respect to adverse events?

A: The proportion of patients with one or more episodes of dizziness and light-headedness at the end of the study was greater in the low-blood-pressure group than in the standard-blood-pressure group (80.7% vs. 69.4%, P=0.002). The frequencies of death, serious cardiovascular or renal events, hyperkalemia, acute kidney injury, and cancer did not differ significantly between the two groups. The proportion of patients who had one or more serious adverse events and symptoms was similar in the two groups.

Table 2. Adverse Events in the 2-by-2 Factorial-Design Trial.

Q: What do the authors conclude about the lack of improvement in the slope of the estimated GFR in cases where treatment decreased the rate of increase in total kidney volume?

A: A beneficial effect on cyst burden (rate of total kidney-volume growth) was not associated with an improvement in the slope of the estimated GFR. Whether a time lag between the therapeutic effect on total kidney volume and stabilization of the estimated GFR occurs in patients with ADPKD is not yet known. Given the combination of the decline in the estimated GFR in the short-term phase and a potential temporal delay between the change in total kidney volume and the change in the estimated GFR, this study was not of sufficient size or duration to show a potential benefit of blood-pressure control on kidney function.

Lactic Acidosis

Posted by Carla Rothaus • December 11th, 2014

When lactic acidosis accompanies low-flow states or sepsis, mortality rates increase sharply. A new review summarizes our current understanding of the pathophysiological aspects of lactic acidosis, as well as the approaches to its diagnosis and management.

Lactic acidosis results from the accumulation of lactate and protons in the body fluids and is often associated with poor clinical outcomes. The effect of lactic acidosis is governed by its severity and the clinical context. Mortality is increased by a factor of nearly three when lactic acidosis accompanies low-flow states or sepsis, and the higher the lactate level, the worse the outcome.

Clinical Pearls

What causes lactic acidosis?

Hyperlactatemia occurs when lactate production exceeds lactate consumption. In tissue hypoxia, whether global or localized, lactate is overproduced and underutilized as a result of impaired mitochondrial oxidation. Even if systemic oxygen delivery is not low enough to cause generalized hypoxia, microcirculatory dysfunction can cause regional tissue hypoxia and hyperlactatemia. Hyperlactatemia can also result from aerobic glycolysis, a term denoting stimulated glycolysis that depends on factors other than tissue hypoxia.  Activated in response to stress, aerobic glycolysis is an effective, albeit inefficient, mechanism for rapid generation of ATP. In the hyperdynamic stage of sepsis, epinephrine-dependent stimulation of the (beta)2-adrenoceptor augments the glycolytic flux both directly and through enhancement of the sarcolemmal Na+,K+-ATPase (which consumes large quantities of ATP). Other disorders associated with elevated epinephrine levels, such as severe asthma (especially with overuse of beta2-adrenergic agonists), extensive trauma, cardiogenic or hemorrhagic shock, and pheochromocytoma, can cause hyperlactatemia through this mechanism. Drugs that impair oxidative phosphorylation, such as antiretroviral agents and propofol, can augment lactic acid production and on rare occasions cause severe lactic acidosis. Cardiogenic or hypovolemic shock, severe heart failure, severe trauma, and sepsis are the most common causes of lactic acidosis, accounting for the vast majority of cases.

Table 1. Causes of Lactic Acidosis.

How is lactic acidosis diagnosed?

An elevated serum anion gap, particularly a value higher than 30 mmol per liter, can provide supportive evidence. However, other causes of a raised anion gap, such as ketoacidosis and toxic alcohol ingestion, should always be considered. A normal anion gap does not rule out lactic acidosis. In one study, 50% of patients with a serum lactate level of 5 to 10 mmol per liter did not have an elevated anion gap. Correction of the anion gap for the effect of serum albumin can improve its sensitivity, but many cases will still escape detection. Therefore, the serum anion gap lacks sufficient sensitivity or specificity to serve as a screening tool for lactic acidosis. An elevated blood lactate level is essential for confirmation of the diagnosis. Previously, the definition of lactic acidosis included a blood pH of 7.35 and a serum [HCO3-] of 20 mmol per liter or lower. However, the absence of one or both of these features because of coexisting acid-base disorders does not rule out lactic acidosis.

Morning Report Questions

Q: What general approaches should guide management of lactic acidosis?

A: Restoring tissue perfusion after hemodynamic compromise is essential in the treatment of patients with lactic acidosis. Vasopressors and inotropic agents should be administered as needed. Crystalloid and colloid solutions are both effective in restoring tissue perfusion in patients with sepsis or hypovolemia. Red-cell transfusions should be administered to maintain the hemoglobin concentration at a level above 7 g per deciliter. An adequate PO2 should be maintained by ensuring an appropriate inspired oxygen concentration, with endotracheal intubation and mechanical ventilation as needed. Given the potentially deleterious effects of an acidic environment, some clinicians recommend therapy with intravenous sodium bicarbonate for severe acidemia (blood pH, <7.2). However, the value of bicarbonate therapy in reducing mortality or improving hemodynamics remains unproven. Using dialysis to provide bicarbonate can prevent a decrease in ionized calcium, prevent volume overload and hyperosmolality (potential complications of bicarbonate infusion), and remove substances associated with lactic acidosis, such as metformin. Resuscitative efforts should be complemented by measures targeting the cause or causes of lactic acidosis.

Q: How should a patient be monitored for the development of lactic acidosis?

A: Measurement of the blood lactate level remains the cornerstone of monitoring for lactic acidosis. Lactate can be measured in arterial or venous blood, since the values are virtually interchangeable. An interval of 2 to 6 hours has been suggested for repeat lactate measurements, but this issue has not been examined rigorously. Changes in levels of blood lactate have been used to guide therapy. In a randomized, controlled study, a reduction of at least 20% in serum lactate levels every 2 hours was targeted for the first 8 hours of resuscitation; achievement of this target of lactate clearance was associated with decreased morbidity and mortality. Evidence that in seriously ill patients even lactate levels at the upper end of the normal range are associated with poor clinical outcomes argues for the normalization of blood lactate as a primary goal of therapy.

Table 2. Measures for Monitoring and Goals of Therapy in Patients with Lactic Acidosis.

Join the conversation on the NEJM Group Open Forum

Posted by Karen Buckley • December 9th, 2014

Two active conversations await your participation on the NEJM Group Open Forum, powered by Medstro, a social professional network for physicians.

Dr. Julian Seifter, author of the recent Review Article, “Integration of Acid-Base and Electrolyte Disorders,” is on hand to answer your questions on this topic.

Meet “Fascinating Physician” Andrey Ostrovsky, a Pediatrics Senior Resident at Boston Children’s Hospital whose numerous accomplishments include founding three companies and working as Health Policy Fellow to a US Senator. Ask him how he manages it all.

The forum is publicly available for all to view, but in order to comment you must register with Medstro — a simple, one-minute process. Look for two new discussions on December 18.