Immunocapture and microplate-based activity and quantity measurement of pyruvate dehydrogenase in human peripheral blood mononuclear cells

Thiamine as a metabolic resuscitator after in-hospital cardiac arrest

INTRODUCTION

Elevated lactate is associated with mortality after cardiac arrest. Thiamine, a cofactor of pyruvate dehydrogenase, is necessary for aerobic metabolism. In a mouse model of cardiac arrest, thiamine improved pyruvate dehydrogenase activity, survival and neurologic outcome.

AIM

To determine if thiamine would decrease lactate and increase oxygen consumption after in-hospital cardiac arrest.

METHODS

Randomized, double-blind, placebo-controlled phase II trial. Adult patients with arrest within 12 hours, mechanically ventilated, with lactate ≥ 3 mmol/L were included. Randomization was stratified by lactate > 5 or ≤ 5 mmol/L. Thiamine 500 mg or placebo was administered every 12 hours for 3 days. The primary outcome of lactate was checked at baseline, 6, 12, 24, and 48 hours, and compared using a linear mixed model, accounting for repeated measures. Secondary outcomes included oxygen consumption, pyruvate dehydrogenase, and mortality.

RESULTS

Enrollments stopped after 36 patients due Data Safety and Monitoring Board concern about potential harm in an unplanned subgroup analysis. There was no overall difference in lactate (mean difference at 48 hours 1.5 mmol/L [95% CI -3.1-6.1], global p = 0.88) or any secondary outcomes. In those with randomization lactate > 5 mmol/L, mortality was 92% (11/12) with thiamine and 67% (8/12) with placebo (p = 0.32). In those with randomization lactate ≤ 5 mmol/L mortality was 17% (1/6) with thiamine and 67% (4/6) with placebo (p = 0.24). There was a significant interaction between randomization lactate and the effect of thiamine on survival (p = 0.03).

CONCLUSIONS

In this single center trial thiamine had no overall effect on lactate after in-hospital cardiac arrest.

Thiamine as a metabolic resuscitator after out-of-hospital cardiac arrest

INTRODUCTION

Thiamine is a key cofactor for aerobic metabolism, previously shown to improve mortality and neurological outcomes in a mouse model of cardiac arrest. We hypothesized that thiamine would decrease lactate and improve outcomes in post-arrest patients.

METHODS

Single center, randomized, blinded, placebo-controlled, Phase II trial of thiamine in adults within 4.5 hours of return of spontaneous circulation after out-of-hospital cardiac arrest (OHCA), with coma and lactate ≥ 3 mmol/L. Participants received 500 mg IV thiamine or placebo twice daily for 2 days. Randomization was stratified by lactate > 5 or ≤ 5 mmol/L. The primary outcome of lactate was checked at baseline, 6, 12, and 24 hours, and compared using a linear mixed model to account for repeated measures. Secondary outcomes included SOFA score, pyruvate dehydrogenase, renal injury, neurological outcome, and mortality.

RESULTS

Of 93 randomized patients, 76 were enrolled and included in the analysis. There was no difference in lactate over 24 hours (mean difference 0.34 mmol/L (95% CI: -1.82, 2.50), p = 0.43). There was a significant interaction between randomization lactate subgroup and the effect of the intervention on mortality (p = 0.01) such that mortality was higher with thiamine in the lactate > 5 mmol/L group and lower with thiamine in the < 5 mmol/L group. This subgroup difference prompted the Data and Safety Monitoring Board to recommend the study be terminated early. PDH activity increased over 72 hours in the thiamine group. There were no differences in other secondary outcomes.

CONCLUSION

In this single-center randomized trial, thiamine did not affect lactate over 24 hours after OHCA.

Thiamine as adjunctive therapy for diabetic ketoacidosis (DKAT) trial protocol and statistical analysis plan: a prospective, single-centre, double-blind, randomised, placebo-controlled clinical trial in the USA

INTRODUCTION

Diabetic ketoacidosis (DKA) is a potentially life-threatening diabetic complication. Despite the high prevalence of DKA and the substantial associated healthcare burden, limited research on strategies to improve outcomes currently exists.Thiamine (vitamin B1) is a cofactor of pyruvate dehydrogenase, which plays a key role in aerobic glucose metabolism. Thiamine deficiency is common in patients with DKA, resulting in a shift to anaerobic metabolism and hyperlactatemia, which can prolong and complicate recovery. Therefore, we hypothesise that thiamine administration will improve aerobic metabolism and lead to faster resolution of acidemia in patients with DKA.

METHODS AND ANALYSIS

In this single centre, double-blind, randomised, placebo-controlled, parallel group interventional trial, 100 patients admitted to the hospital with DKA will be randomised to receive either intravenous thiamine (200 mg in 50 mL 0.9% saline) or placebo (0.9% saline identical in appearance and volume) two times per day for 2 days. The primary outcome will be the change in bicarbonate level over 24 hours as compared between the two treatment groups. Additional secondary outcomes include the change over time in anion gap, lactate levels, oxygen consumption by circulating mononuclear cells, intensive care unit and hospital length-of-stay and hospital resource usage when comparing the two study arms.

ETHICS AND DISSEMINATION

This trial was approved by the Committee on Clinical Investigations, the institutional review board of Beth Israel Deaconess Medical Center (protocol number 2018P000475). Findings will be disseminated through peer-reviewed publications and professional conference presentations.

TRIAL REGISTRATION NUMBER

NCT03717896; clinicaltrials.gov.

The Effect of a Single Dose of Thiamine on Oxygen Consumption in Patients Requiring Mechanical Ventilation for Acute Illness: A Phase II, Randomized, Double-Blind, Placebo-Controlled Trial

Lower oxygen consumption is associated with worse survival in septic shock and in other forms of critical illness. No treatment that increases oxygen extraction, a key determinant of oxygen consumption, has been found. Thiamine is required for aerobic metabolism, and deficiency is common in the critically ill.

OBJECTIVES

We evaluated the effect of thiamine on oxygen consumption in patients requiring mechanical ventilation for an acute illness.

DESIGN

Phase II, randomized, double-blind, and placebo-controlled trial.

SETTING AND PARTICIPANTS

ICUs in a tertiary care hospital in the United States. Patients admitted to the ICU and requiring mechanical ventilation were screened for enrollment.

INTERVENTIONS

After enrollment, baseline measurement of oxygen consumption and baseline laboratories including lactate, central venous oxygen saturation, and pyruvate dehydrogenase, a single dose of 200 mg IV thiamine or placebo was administered. Oxygen consumption was then monitored for 6 additional hours and repeat laboratories were drawn at the end of the protocol.

MAIN OUTCOMES AND MEASURES

The primary outcome was the change in oxygen consumption. Analysis was done using linear regression with a first-order autoregressive variance-covariance structure to account for repeated measures within subjects. Secondary outcomes included change in lactate, central venous oxygen saturation, and pyruvate dehydrogenase quantity and activity.

RESULTS

Sixty-seven patients were enrolled. After excluding 11 patients due to inadequate quantity or quality of oxygen consumption data, 56 patients were included. There was no difference in change in oxygen consumption in the 6 hours after study drug. Results for secondary outcomes were similarly negative. In the prespecified subgroup of 18 thiamine deficient patients, there was a difference in the two oxygen consumption curves (p = 0.006), although no difference in median oxygen consumption or area under the curve.

CONCLUSIONS AND RELEVANCE

A single dose of IV thiamine did not alter oxygen consumption in patients requiring mechanical ventilation for acute illness.

Pyruvate Dehydrogenase Activity Is Decreased in the Peripheral Blood Mononuclear Cells of Patients with Sepsis. A Prospective Observational Trial

RATIONALE

Rodent studies have shown that pyruvate dehydrogenase (PDH) levels are low in sepsis. This may cause cells to shift to anaerobic metabolism, resulting in increased lactate production. Alterations in PDH during sepsis have never been studied in humans.

OBJECTIVES

The objective of this pilot study was to measure PDH activity and quantity in patients with severe sepsis.

METHODS

We conducted a pilot case-control study at a single urban tertiary care center. We compared PDH activity and quantity between patients with severe sepsis admitted to the intensive care unit and healthy control subjects. PDH activity and quantity were measured in isolated peripheral blood mononuclear cells. We measured PDH activity and quantity in control subjects at baseline and in patients with sepsis at 0 (baseline), 24, 48, and 72 hours.

MEASUREMENTS AND MAIN RESULTS

We enrolled 56 patients with sepsis and 20 control subjects with at least one blood sample being drawn from each patient. PDH activity and quantity in the sepsis group were significantly lower than the control group (P < 0.001). In multivariable linear regression adjusting for age, race, sex, and assay plate, the difference remained significant. Patients with sepsis who died had significantly lower PDH activity compared with those who survived (P = 0.03).

CONCLUSIONS

PDH activity and quantity is decreased in peripheral blood mononuclear cells of humans with severe sepsis when compared with healthy control subjects, and may be associated with mortality. Whether decreased PDH activity plays a role in lactate metabolism or whether pharmacologic modification of PDH activity may improve outcomes remains unknown.

Pyruvate Dehydrogenase Activity Is Decreased in Emergency Department Patients With Diabetic Ketoacidosis

OBJECTIVES

The pyruvate dehydrogenase complex (PDH) is an essential enzyme in aerobic metabolism. Ketones are known to inhibit PDH activity, but the extent of this inhibition is unknown in patients with diabetic ketoacidosis (DKA).

METHODS

We enrolled adult patients presenting to the emergency department in hyperglycemic crisis. Patients were classified as DKA or hyperglycemia without ketoacidosis based on laboratory criteria. Healthy controls were also enrolled. PDH activity and quantity were measured in isolated peripheral blood mononuclear cells. We compared PDH values between groups and measured the relationship of PDH values to measures of acid-base status.

RESULTS

Twenty-seven patients (17 with DKA) and 31 controls were enrolled. Patients with DKA had lower PDH activity and quantity compared to the two other groups. PDH activity was significantly correlated with serum bicarbonate and pH and inversely correlated with the anion gap.

CONCLUSIONS

DKA is associated with greater suppression of PDH activity than hyperglycemia without ketoacidosis, and this is correlated with measures of acid-base status. Future studies may determine whether PDH depression plays a role in the pathophysiology of DKA and whether modification of PDH could decrease time to DKA resolution.

Thiamine as a neuroprotective agent after cardiac arrest

AIMS

Reduction of pyruvate dehydrogenase (PDH) activity in the brain is associated with neurological deficits in animals resuscitated from cardiac arrest. Thiamine is an essential co-factor of PDH. The objective of this study was to examine whether administration of thiamine improves outcomes after cardiac arrest in mice. Secondarily, we aimed to characterize the impact of cardiac arrest on PDH activity in mice and humans.

METHODS

Animal study: Adult mice were subjected to cardiac arrest whereupon cardiopulmonary resuscitation was performed. Thiamine or vehicle was administered 2min before resuscitation and daily thereafter. Mortality, neurological outcome, and metabolic markers were evaluated. Human study: In a convenience sample of post-cardiac arrest patients, we measured serial PDH activity from peripheral blood mononuclear cells and compared them to healthy controls.

RESULTS

Animal study: Mice treated with thiamine had increased 10-day survival (48% versus 17%, P<0.01) and improved neurological function when compared to vehicle-treated mice. In addition, thiamine markedly improved histological brain injury compared to vehicle. The beneficial effects of thiamine were accompanied by improved oxygen consumption in mitochondria, restored thiamine pyrophosphate levels, and increased PDH activity in the brain at 10 days. Human study: Post-cardiac arrest patients had lower PDH activity in mononuclear cells than did healthy volunteers (estimated difference: -5.8O.D./min/mg protein, P<0.001).

CONCLUSIONS

The provision of thiamine after cardiac arrest improved neurological outcome and 10-day survival in mice. PDH activity was markedly depressed in post-cardiac arrest patients suggesting that this pathway may represent a therapeutic target.

Thiamine as an adjunctive therapy in cardiac surgery: a randomized, double-blind, placebo-controlled, phase II trial

Background

Thiamine is a vitamin that is essential for adequate aerobic metabolism. The objective of this study was to determine if thiamine administration prior to coronary artery bypass grafting would decrease post-operative lactate levels as a measure of increased aerobic metabolism.

Methods

We performed a randomized, double-blind, placebo-controlled trial of patients undergoing coronary artery bypass grafting. Patients were randomized to receive either intravenous thiamine (200 mg) or placebo both immediately before and again after the surgery. Our primary endpoint was post-operative lactate levels. Additional endpoints included pyruvate dehydrogenase activity, global and cellular oxygen consumption, post-operative complications, and hospital and intensive care unit length of stay.

Results

Sixty-four patients were included. Thiamine levels were significantly higher in the thiamine group as compared to the placebo group immediately after surgery (1200 [683, 1200] nmol/L vs. 9 [8, 13] nmol/L, p < 0.001). There was no difference between the groups in the primary endpoint of lactate levels immediately after the surgery (2.0 [1.5, 2.6] mmol/L vs. 2.0 [1.7, 2.4], p = 0.75). Relative pyruvate dehydrogenase activity was lower immediately after the surgery in the thiamine group as compared to the placebo group (15 % [11, 37] vs. 28 % [15, 84], p = 0.02). Patients receiving thiamine had higher post-operative global oxygen consumption 1 hour after the surgery (difference: 0.37 mL/min/kg [95 % CI: 0.03, 0.71], p = 0.03) as well as cellular oxygen consumption. We found no differences in clinical outcomes.

Conclusions

There were no differences in post-operative lactate levels or clinical outcomes between patients receiving thiamine or placebo. Post-operative oxygen consumption was significantly increased among patients receiving thiamine.

Trial registration

clinicaltrials.gov NCT02322892, December 14, 2014

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1245-1) contains supplementary material, which is available to authorized users.