In another sign of his increasing frailty, the pope has begun receiving nutrition through a feeding tube in his nose, the Vatican said, acknowledging the pope's recovery from surgery last month has been "slow."
In a statement Wednesday, Vatican spokesman Joaquin Navarro-Valls said John Paul had been outfitted with a nasogastric tube to "improve the calorie intake and favor an effective recovery of strength."
John Paul's brief appearance at his studio window Wednesday was his second unsuccessful attempt to speak to the crowds in St. Peter's Square that week.
After managing just a rasp of his voice, he blessed well-wishers by making the sign of the cross with his hand and withdrew.
On Easter Sunday, the other appearance, mass was tinged with sadness, CBS News Correspondent Allen Pizzey reports. On the day when John Paul usually blesses the world in sixty languages, he could not utter a single intelligible word.
A feeding tube is common in people requiring supplemental nutrition. Implementation involves threading a plastic tube down the nose and throat and into the stomach, allowing liquid food to be fed directly to the stomach.
Dr. Barbara Paris, director of geriatrics at Maimonides Medical Center in New York, said the nasogastric tube might be just a temporary measure to boost John Paul's nutrition while he continues his recovery. But she said it could also be the first step toward having a more permanent feeding tube inserted directly into his stomach.
That procedure, known as PEG — percutaneous endoscopic gastrostomy — involves making a surgical incision in the abdomen so that a feeding tube can be passed directly into the stomach, bypassing the throat altogether.
The nasogastric tube is less invasive and a simpler solution to the PEG procedure, but is not generally used for long-term supplemental feeding, Paris said.
Terri Schiavo, the severely brain-damaged woman at the center of a right-to-die legal battle in the United States, was fed for years by a PEG tube before it was removed earlier this month.
While the nasogastric tube is uncomfortable for the patient, no sedation or surgery is required. John Paul can eat and speak with it in place, experts said.
The Vatican has not said when the tube was inserted; none was visible during John Paul's appearance Wednesday.
In the statement, Navarro-Valls said John Paul is continuing his "slow and progressive convalescence" from a tracheotomy Feb. 24. In that surgery, a tube was inserted in John Paul's throat to help him breathe.
He said John Paul spends "many hours" seated in an armchair, celebrates Mass in his private chapel and has work contacts with his aides "following directly the activities of the Holy See and the life of the church."
But he said John Paul's public audiences remain suspended.
He also said medical assistance is being provided by the Vatican medical staff under the direction of the pope's personal physician, Dr. Renato Buzzonetti — an apparent reference to reports that outside medical help had been called in.
The insertion of the feeding tube was the latest in a series of interventions for the frail 84-year-old pope, who has battled Parkinson's disease for years as well as hip and knee ailments that have made it virtually impossible for him to sit or stand.
In addition to the tracheotomy, the pope has had an inflamed appendix and benign tumor on his colon removed, and he underwent hip replacement surgery after falling in the bathroom in 1994. He was shot in the abdomen in 1981.
The pope was rushed to Gemelli Polyclinic hospital twice last month with breathing crises. He last spoke to the public on March 13, shortly before being discharged from hospital a second time.
Since then, he has been unable to speak publicly. On Easter Sunday, he tried but failed to deliver his "Urbi et Orbi" blessing to tens of thousands of people gathered for Easter Mass, making only a few sounds into the microphone before giving up.
Pizzey reports that the pope's feeding tube and uncertain prognosis for the future begs the question of what happens if John Paul II becomes incapacitated.
In such a case, the church has bio-ethics guidelines to deal with life-support issues. For instance, in the case of Teri Schiavo, the Vatican has called for her life to be sustained.
But it is not against shutting off life-prolonging systems that it defines as "overzealous … extraordinary or disproportionate."
If the pope faced an end-of-life medical decision and could not vocalize it himself, ethics professor Father Robert Gahl told Pizzey, "that decision would probably be made by his personal secretary."
"He looks very frail but certainly very committed to seeing his people," said Kate Strauss, an American tourist in St. Peter's with her family. "We happened to be here by chance and we just had no idea we'd get a blessing from him and a blessing for the babies."
The Vatican newspaper, L'Osservatore Romano, headlined its Wednesday afternoon editions with the pope's appearance, saying the history of St. Peter's Square was growing more profound every day.
"The gesture of his hand communicated courage, hope, strength," the newspaper said.