"Air hunger is a horrible feeling," Waisel added. "It's the inability to get your breath."
Waisel testified at the beginning of a two-day hearing on the state's new lethal drug process.
Ohio plans to use intravenous doses of two drugs, midazolam, a sedative, and hydromorphone, a painkiller, to put McGuire to death. The method has been part of Ohio's execution process since 2009, though never used. It was chosen because of a shortage of other lethal injection drugs.
The state says its own anesthesiology expert is ready to argue that experiments have shown nothing of the sort will happen.
Such dueling arguments have taken place often in federal judge Gregory Frost's courtroom over the years. Frost has heard numerous arguments for and against Ohio's lethal injection process.
He has never ruled the drugs themselves unconstitutional, but he has at times harshly criticized the state for conducting haphazard executions by not closely following its own policies.
McGuire, 53, was sentenced to die for the 1989 rape and fatal stabbing of Joy Stewart in Preble County in western Ohio. The 22-year-old Stewart was newly married and pregnant.
"McGuire will experience the agony and terror of air hunger as he struggles to breathe for five minutes after defendants intravenously inject him with the execution drugs," the inmate's attorneys said in a Monday court filing.
Higher courts have twice rejected claims that the drugs pose a risk of severe pain, the state argued in opposing McGuire's attempt to stop his execution.
The state says that because courts have upheld the use of those drugs in the backup method, McGuire can't challenge their use just because they are to be given intravenously.
There is no excuse for not raising this claim years ago, "much less presenting it for the first time in an eleventh-hour stay of execution," lawyers for the Ohio attorney general's office said in their filing.
Late Wednesday, McGuire's attorneys filed a separate appeal with the U.S. Supreme Court, saying information about his chaotic childhood of abuse and neglect could have prevented him from being sentenced to death if it was presented at trial.
The filings argue McGuire was so malnourished as a child that his stomach was swollen and distended. He also had to frequently steal food for himself and his younger sister, the appeal said.
McGuire was physically abused by at least four different parental figures and shows signs of brain damage from head trauma, the attorneys said.
The filings say jurors who sentenced McGuire to death never got to hear the full extent of his chaotic childhood because his trial attorneys didn't properly investigate reasons he should be spared.
Even without the full picture of McGuire's life, a juror held out for 12 hours before relenting, a sign that a full investigation might have led to a different outcome, the lawyers said. In Ohio, one juror can block a death sentence by voting against it.
The state's response to that claim is expected Monday.