Bright Light Exposure in Surgical Patients

PER2 transcript and protein levels in patients undergoing cardiac surgery following intense light therapy utilizing blood samples, buccal swaps and right atrial myocardium. In addition, we will examine the correlation of PER2 levels and PER2 related metabolism and perform a whole genome microarray screen from the collected tissue/blood samples.

Patients will be enrolled 10 to 1 days prior to surgery and will either receive an intense (bright light) box or a placebo/control device (dim/night light box). The patient will start using the light box 7 days prior to surgery every morning from 8.30 to 9.00 AM. The patient will need to keep the box as close as possible to their eyes and not walk away during the treatment period.

1. Blood /buccal swabs will be collected on the day of enrollment (10-1 days prior to surgery) between 7 and 10 AM without any light therapy and on the day of surgery between 7 and 10 AM before anesthesia induction after one week of light/placebo therapy. A small piece of the right atrial myocardium (which stems from cardiac cannulation and is otherwise discarded) will be put in liquid nitrogen in the OR and stored for further analysis. In addition, we will draw a blood sample 72 hrs. after surgery and determine Troponin I levels. Investigating this patient population will give the necessary evidence if light could also be effective in a perioperative setting to prevent or decrease damage to the myocardium during high risk cardiac surgery. In addition, it will help us understand if light could be used in general to prevent or treat heart ischemia.
2. We will use our light boxes for 30 minutes in ICU care patients on the first morning after admission from 8.30 to 9.00 AM. Before light therapy/sunrise and immediately after light therapy, a blood sample is drawn. These samples will be analyzed for melatonin levels. We have demonstrated that effective intense blue intense light therapy significantly suppresses melatonin plasma levels in health human volunteers which is the desired outcome of light therapy. We also have shown that light exposure via windows does not achieve such a result. Light therapy will be continued for up to 10 days, and blood samples are drawn each morning before sunrise and after light therapy. In patients that are sedated and have their eyes closed, eyes will be opened manually and lubricated before light therapy is initiated. The sample size will be n=40 (10 light treatment 5 days, 10 light treatment 10 days and 10 standard room light treatment 5 and 10 days). Additional readouts from plasma sample will be triglyceride and ANGPTL4 levels as we have already shown that intense light significantly downregulates triglycerides in healthy volunteers. Further, we recently discovered ANGPTL4 as major light dependent protein. ANGPTL4 is a key regulator of triglycerides and of endothelial function in humans and triglyceride levels are also indicative of endothelial function. This approach will allow us to evaluate the effectiveness of our light therapy approach and will further give insight into light elicited endothelial mechanisms in humans.

To further study endothelial function, we will use the Endo_PAT device (Itamar Medical Ltd, Franklin, MA) which has been shown to reliably detect endothelial dysfunction and alterations in critical ill patients. This device has been shown to even work when patients who are on vasopressor therapy. This device is noninvasive and works like an SpO2 monitor with built in cuff pressure measurement.

Finally, we will use Actigraphy (Actiwatch, Phillips) to analyze circadian patterns and associated changes following light therapy. We already have purchased FDA approved Actigraphy devices and shown that intense light strengthens the circadian rhythms in healthy volunteers. Watches will be around the wrist for the duration of the light therapy and are noninvasive.