Reporter's notebook: Ukrainian doctor recounts 'non-stop carnage,' seeing 15,000 casualties

DONBAS REGION, Ukraine -- Andrii Semiankiv, a renowned Ukrainian novelist and doctor, says he has attended to around 15,000 wounded soldiers throughout the war.

"I've long past the point where I can emotionally react or I can assess the reality of what is happening," he told ABC News at a medical "stabilization point" -- or "stab point" for short -- situated close to the frontlines.

A soldier named Volodymyr was brought in with shards of shrapnel in his back, which were quickly removed by the dedicated team of young medics.

A Russian drone dropped a grenade on Volodymyr whilst he was trying to recover the body of a dead comrade.

"Our losses are heavy," Volodymyr told us. "I've lost so many friends."

Compared to the "carnage" that Semiankiv and his team regularly witness, Volodymyr's wounds were considered minor.

On a busy night, as many as 80 wounded soldiers can arrive at the "stab point" in a matter of hours.

Semiankiv appears to be one of those impressive people you rarely meet. He's stoical and calm but admits he has seen so many shredded limbs and other horrific injuries that he is now numb to their effect.

He doesn't allow himself to have hope. Amid the endless horror of Ukraine's war, he says, hope is not a helpful thing. He just serves.

And he serves, he says, because he can remember the faces of people he has lost, medics who bravely went to try and pull the wounded off the battlefield and were killed in the process.

In another part of the battle zone, the deep snow filling the trench-line looks pretty, masking the ugliness of war and the danger lurking in the countryside nearby.

Our team has arranged to spend no more than one hour at a Ukrainian artillery position.

We're several miles back from the frontlines but the greatest risk is that Russian one-way explosive attack drones, which are proving deadly for Ukrainian troops, could be within striking distance overhead.

Next to their American-supplied M777 howitzer, Valeriy, the commander of this artillery unit from Ukraine's 45th Artillery Brigade shows us their artillery rounds, stacked up in a bunker.

There are just 20 shells. The commander says they had around 150 to 200 rounds to fire on any given day in the summer.

Back then, Ukraine was on the offensive, and its artillery was blasting Russian positions in a more impressive way to lend cover to advancing troops.

However Ukraine's diminishing number of shells and Russia's "seemingly limitless supply," as one Ukrainian soldier put it is indicative of how the tables have turned.

Russian forces are now on the front foot in this war. According to Ukrainian soldiers, Russia has more artillery, more lethal drones, more attack helicopters and fighter jets and has a larger supply of men which it can throw into battle.

Meanwhile the lack of Ukrainian artillery firepower, says Valeriy, a commander in the 45th Brigade is costing the lives of Ukrainian troops.

With the U.S. Congress still blocking additional funding, the White House says it is, for now, unable to send any more military aid to Ukraine.

Vadim, another of the soldiers, makes an appeal directly into our camera, aimed at American lawmakers.

"Dignified members of Congress … it's now or never, tomorrow could be too late," he says.

If Ukraine's stocks of ammunition are under pressure, the country's reserves of trained soldiers are being strained too.

Mounting casualties mean the Ukrainian government is expected to soon announce a fresh wave of mobilization.

Back at the medical "stabilization point," Semiankiv says he is "bitter" about waiting for U.S. lawmakers to provide Ukraine with more funding. He claims it is costing "hundreds of lives which cannot be brought back."

"I don't get it," he says. "I don't understand why the decision on supporting Ukraine is so difficult and controversial."