Zannini said his hospital has been deluged with patients and said in the early hours, many of them died. His facility has received a shipment of antibiotics, blankets and other supplies and said his staff is even capable of doing surgeries now.
He said the most common injury among the more than 1,500 patients his doctors have seen is the "open fracture," or a compound fracture when the bone breaks through the skin.
There are already more than 300 American military troops on the ground in Haiti with thousands more expected in the coming days.
Emilia Casella of the U.N. World Food Program said the next few days will be critical as Haitians become increasingly hungry and thirsty, and as the cries of those trapped become fainter and their families become frantic.
Nevertheless, it seems to be almost impossible to speed up relief.
"The physical destruction is so great that physically getting from point A to B with the supplies is not an easy task," Casella told a news conference. "Pictures can get out instantly ... and that's important because the world needs to know. But getting physically tons and tons of equipment and food and water is not as instant as Twitter or Skype or 24-hour television news."
U.N. humanitarian spokeswoman Elisabeth Byrs said peacekeepers were maintaining security in Haiti, despite the challenges.
"It's tense but they can cope," Byrs said. "People who have not been eating or drinking for almost 50 hours and are already in a very poor situation, if they see a truck with something ... or if they see a supermarket which has collapsed, they just rush to get something to eat."
President Bill Clinton, who has been tapped along with President George W. Bush, to coordinate relief efforts in Haiti, said delays in supplies reaching victims is inevitable in a disaster of this magnitude. He pointed out that the very first plane on the ground -- an Air China flight—took six hours just to unload.
The U.N. was planning to ask governments later today for $550 million in humanitarian pledges for Haiti.
Though several rescue teams have made it into Haiti and pulled dozens out of the rubble, more rescue workers have paced the floors in a holding center in the Dominican Republic, frustrated that every second they are delayed means someone else may be dying.
American missionary Christa Brelsford said she knows exactly how lucky she is. Recovering in a Miami hospital, Brelsford lost her leg in the earthquake when the building she was in collapsed on top of her as she raced down the stairs.
Pinned between the roof and a concrete staircase, Brelsford's brother, also in Haiti at the time, and three Haitians worked for a half-hour to free her. Brelsford told "Good Morning America" today that she had no idea that her leg was crushed to the point of being almost disconnected.
"I thought that I could still wiggle," she said. "I was wiggling all of my toes."
Once free, Brelsford was thrown on the back of a motorcyle and raced to the Sri Lankan military peace-keeping mission, where officials treated her with a splint, cookies and cough drops.
She was also given the opportunity to e-mail her family in the U.S., telling them about the damage to her leg, but "otherwise, I'm fine."
"I hope they get the best care they can as soon as possible," she said of everyone else still in Port-au-Prince. "There are a lot of unmet medical needs right now. I know that I was incredibly lucky."