Light Therapy in Cardiopulmonary Bypass Surgery

Study Overview
=================
Brief Summary
-----------------
The goal of this study is to determine whether or not exposure to blue spectrum light reduces acute kidney injury and systemic inflammation in subjects undergoing cardiopulmonary bypass. Subjects scheduled to undergo cardiopulmonary bypass surgery will be exposed to either bright (1000 lux) blue spectrum (480nm) light or to ambient, white fluorescent light for a 24 hour photoperiod the day prior to surgery and for a 24 hour photoperiod in the immediate postoperative period.

Detailed Description
-----------------
Light modifies the biology and physiology of mammals, including humans. The cellular biology of both the immune system, as well as, the cells comprising tissues and organs (e.g., kidney, liver) are under the regulation of light and exhibit circadian rhythms. Studies show that the severity of organ injury varies with the time of the day, the duration of the day, and the season. This variation is due to the biology of circadian rhythms, and light is the principle environmental cue entraining circadian biology. More recent data suggest that modulating the spectrum of light to which an organism is exposed may therapeutically modulate the cellular response to stress or injury. Specifically, exposure to a short (24 hour) photoperiod of high illuminance, blue spectrum light attenuated liver and kidney injury when animals were subjected to ischemia/reperfusion (I/R), a model in which the blood flow to an organ is temporarily reduced and then restored. A predominant cause of organ injury in this model is the misdirected and exacerbated inflammation of a type of immune cell called the neutrophil. However, blue light inhibited neutrophil infiltration into the ischemic kidney and liver, and thereby reduced inflammation and neutrophil-mediated organ injury. Cardiopulmonary bypass (CPB) surgery is an operation characterized by excessive inflammation and a high risk of organ injury, particularly acute kidney injury (AKI). Thus, we hypothesize that exposure to blue light, by comparison to standard environmental, white fluorescent light, will reduce inflammation, organ injury and improve the outcome of patients undergoing CPB.

Official Title
-----------------
Light Therapy in Cardiopulmonary Bypass Surgery

Conditions
-----------------
Acute Kidney Injury, Inflammation

Intervention / Treatment
-----------------
* Other: Blue light


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: age greater than or equal to 18 years undergoing cardiopulmonary bypass surgery Exclusion Criteria: Blindness Immunocompromised or immunosuppressed state Anticipated survival < 24 hours

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Blue light<br>Exposure to high illuminance (1000 lux), blue spectrum (480nm) light for the 24 hour photoperiod prior to surgery and for the 24 hour photoperiod immediately after surgery | Other: Blue light<br>* Exposure to high illuminance (1000 lux), blue spectrum (480 nm) light for a 24-hour photoperiod immediately before surgery and a 24-hour photoperiod immediately after surgery<br>|
| No Intervention: Ambient light<br>Exposure to ambient, white fluorescent light | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in creatinine concentration | The change in serum creatinine after intervention compared to baseline. | Change in serum creatinine concentration at 24 hours after surgery compared to preoperative baseline creatinine concentration | 
| Change in blood urea nitrogen (BUN) concentration | The change in serum BUN after intervention compared to baseline. | Change in serum BUN concentration at 24 hours after surgery compared to preoperative baseline BUN concentration | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Inflammation | The change in serum concentration of inflammatory mediators after intervention compared to baseline. | Change in serum cytokine concentrations comparing serum concentrations at 24 hours after surgery to serum concentrations immediately (with 1 hour) after surgery | 
| all cause mortality | Death 28 days after surgery and intervention | within 28 days after surgery | 
| duration of ICU stay | ICU length of stay 28 days after surgery and intervention | within 28 days after surgery | 
| duration of hospital stay | Hospital length of stay 28 days after surgery and intervention | within 28 days after surgery | 
| Ventilator-free days | Cumulative days without mechanical ventilation 28 days after surgery and intervention | within 28 days after surgery | 
| Duration of renal replacement therapy | Days of dialysis within the first 28 days after surgery and intervention | within 28 days after surgery |