How can I get my sister's medical records years after her death?

My sister died in December 28, 2003 after being sick for only 9 days. All of those days were spent in the ICU on a ventilator. Her death certificate lists the cause of death as septic shock and multi-organ dysfunction. She had a blood clot in her foot that was successfully operated on. My question, can I obtain her medical records because I do not believe they knew what she died from. She and I were extremely close and her death still haunts me because no one at the hospital would ever tell us what she died from. She was only 53 and in perfect health.