(CNN) Among 16 immigrants deaths in US government detention centers between December 2015 and April 2017, half resulted from inadequate medical care for detainees in times of need, a new report finds.
The report, published Wednesday, examined 15 of the deaths, which had "detainee deaths reviews" released by US Immigration and Customs Enforcement during this time period. In eight of those deaths, the reviews found a lack of satisfactory medical care which, in turn, contributed to the deaths.
One detainee, Jose Azurida, 54, died of a heart attack. According to the report, a guard immediately alerted a nurse when Azurida began experiencing symptoms, including vomiting and numbness in his arm. But he was not taken to a hospital for two hours. Once there, his heart was too damaged to respond to treatment and he died four days later.
Evidence of substandard medical practices was also identified in six of the remaining death reviews, according to the report by Human Rights Watch, the American Civil Liberties Union, Detention Watch Network and National Immigrant Justice Center.
"ICE has proven unable or unwilling to provide adequately for the health and safety of the people it detains," said Clara Long, a senior US researcher at Human Rights Watch in a statement. "The Trump administration's efforts to drastically expand the already-bloated immigration detention system will only put more people at risk."
A statement sent to CNN from ICE said the agency "takes very seriously the health, safety and welfare of those in our care, including those who come into ICE custody with prior medical conditions or who have never before received appropriate medical care. Any death that happens in ICE custody is a cause for concern."
The statement said agency protocols call for deaths to be reviewed to "determine whether the detainee received appropriate health services in relation to nationally recognized standards of detention health care and practices" and an "objective examination" determines whether detention standards were complied with. Results "are provided to ICE senior management and the Department of Homeland Security's Office of Civil Rights and Civil Liberties."
"ICE is committed to ensuring that everyone in our custody receives timely access to medical services and treatment. Comprehensive medical care is provided from the moment detainees arrive and throughout the entirety of their stay. All ICE detainees receive medical, dental and mental health intake screening within 12 hours of arriving at each detention facility, a full health assessment within 14 days of entering ICE custody or arrival at a facility, and access to daily sick call and 24-hour emergency care," according to the statement.
The new report said that since March 2010, 74 people have died in detention, but death reviews have only been released for 52 of them.
It also notes that death reviews do not represent detainee health care outcomes as a whole, but that the identification of these oversights points to "larger, systemic deficits in immigration detention facility health care."
"The death toll amassed by ICE is unacceptable and has proven that they cannot be trusted to care for immigrants in their custody," said Silky Shah, executive director of Detention Watch Network, a national coalition that exposes the injustices of the US' immigration detention and deportation system.
The report also identified the case of Rafael Barcenas-Padilla, 51, who was prescribed medication for an upper respiratory tract infection by an external doctor who was consulted over the phone. His ICE detention center did not have a nebulizer, a device used to deliver the medication, therefore he was not receiving it and his oxygen levels plummeted. Three days after the sharp decline in oxygen, he was sent to a hospital, where he died of bronchopneumonia.
"ICE puts thousands of people's health and lives at risk by failing to provide adequate medical care to the people it detains for weeks, months, and even years," said Victoria Lopez, senior staff attorney at the American Civil Liberties Union.
In the fiscal year 2017 -- running from October 2016 to September 2017 -- 12 people died in immigration detention, which is more than any year since 2009, according to the report.
That same year, ICE held, on average, 40,500 people per day, the report states. In 1994, this figure was 6,800.
Earlier this year, the Trump administration requested a budget of $2.8 billion to detain 52,000 immigrants each day, a 30% expansion.
"To the extent that Congress continues to fund this system, they are complicit in its abuses," said Heidi Altman, policy director at nongovernmental NGO the National Immigrant Justice Center. "Congress should immediately act to decrease rather than expand detention and demand robust health, safety, and human rights standards in immigration detention."