Two surgeon “whistleblowers” say at least five patients have perished, including one who bled to death, at Brooklyn’s SUNY Downstate Medical Center amid poor care and negligent, boozing doctors, according to charges in two new lawsuits.

A transplant surgeon “abandoned” a patient on the operating table and then couldn’t be reached when his condition went south, according to a lawsuit filed by Dr. John Renz. When the backup surgeon failed at the operation, Renz says he and fellow whistleblower Dr. Rainer Gruessner, who were both out of town, had to fly back to Brooklyn to save the patient.

The transplant surgeon, Nabil Sumrani, also allegedly had an “inappropriate relationship” with a hospital pharmacist, Renz, also a transplant surgeon, claims in court papers.

Another surgeon allegedly left “multiple bottles of alcohol throughout [his] office” and “what appeared to be drug paraphernalia,” which janitors found after his departure, the court documents say. Dr. Devon John is now operating at Westchester Medical Center, where he is head of kidney transplants.

The stunning allegations were made in the Brooklyn Supreme Court lawsuits filed by Renz in January against SUNY and Downstate and by Gruessner in December against SUNY and SUNY Downstate Health Sciences University, which runs the hospital. The doctors say they alerted administrators to the patient safety issues in an attempt to fix the mess, which ultimately led to them being fired.

Gruessner, the former chairman of surgery and chief of transplant, maintains in his suit that a patient bled out when an on-call doctor couldn’t be reached. He alleges three other patients died in one year because of under-staffing at the taxpayer-funded, teaching hospital in East Flatbush.

And in June 2019, a patient went into cardiac arrest and died “at a time when there was not a single attending [doctor] present” and the resident responsible for inserting a breathing tube into the patient was so inexperienced “that he was almost shocked by the defibrillator,” according to Gruessner’ suit.

A SUNY Downstate spokeswoman said the hospital “takes its patient care mission very seriously. We have undertaken an aggressive and rigorous patient safety and quality agenda that advances patient care and creates positive outcomes for individuals in our care. If we see something that is not up to high standards, we investigate and take appropriate action because our patients deserve better.”

The Wall Street Journal, which first reported the doctors’ wrongful-termination claims, said the hospital loses about $3 million a month.

Gruessner, a transplant pioneer who led the team that saved Rep. Gabrielle Giffords at the University of Arizona after she was shot in 2011, came to Brooklyn in May 2017.

He alleges in his suit he quickly found “systemic institutional problems in patient care and safety” and told administrators.

Among the issues was a lack of around-the-clock staffing for heart-surgery patients, a problem that became acute from December 2018 to March 2019 when doctors and physician assistants “could not be relied on” to provide coverage because they had not been fully paid, Gruessner alleges.

“In fact, three inpatient deaths within a one-year period occurred on days in which there was no in-house coverage provided by nurse practitioners and physician assistants,” according to his lawsuit, which further alleges there was no backup pediatric surgeon, putting “the lives of children at risk.”

Gruessner alleges that he and Renz realized that poor outcomes with transplant failures and patient deaths had been caused by patients not getting enough anti-rejection meds, legal papers say.

The July 2019 report of the Scientific Registry of Transplant Recipients showed 14 instances at Downstate when a kidney transplant failed, more than double the expected number of six calculated by the Registry, The Post has learned.

The hospital voluntarily inactivated the program, which also included pancreas transplants, in July. It also stopped doing heart surgery in July.

Gruessner was stripped of his clinical duties in September although he is still a tenured professor.

“While I pursued extensively every avenue to create an environment dedicated to clinical excellence, my efforts were subverted by senior administration when I and my team of physicians raised concerns about Downstate’s failures to address issues of patient safety and health,” he told The Post. “In this respect, they have not only failed me, but more importantly, the people of Brooklyn.”

Renz, who left his job at the University of Chicago to come to Downstate, alleges he told senior management about the lack of “staffing and coverage, medical devices not being regularly or routinely checked and restocked after use, and delays in getting necessary pharmaceutical products and medications.”

In August, Renz says in his complaint, he was informed his appointment would not be renewed “based solely on budgetary concerns” and was told to “discontinue working immediately” and was escorted out by security.

Renz could not be reached. His lawyer, Peter Weidman, would not comment. Drs. John and Sumrani did not return messages seeking comment.