Before rolling into the operating room, Ms. Tomczak joined in a short prayer. Then she asked Dr. Scheinin if he had gotten plenty of rest. “I don’t want to hear any ‘oopses,’ ” she said.

Before surgery, doctors ordered doses of intravenous iron and Aranesp, a drug that stimulates red cell production. They also limited the number of blood draws for lab testing. Every milliliter might count.

As Dr. Scheinin opened the thoracic cavity and began cauterizing his way through tissue, another surgeon suctioned blood with a long tube. Rather than disposing of it as medical waste, he routed it through a hose into the cylinder of a cell salvage machine.

A centrifuge spun out the heavy red cells, which were washed with saline and later returned through a port in Ms. Tomczak’s jugular vein. The church does not view this as a transfusion because the blood ostensibly remains in a continuous circuit with the body.

The same was true of a process called hemodilution. At the outset of the operation, doctors ordered a unit of whole blood removed from Ms. Tomczak and replaced it with saline to maintain her blood pressure. The process diluted the hemoglobin concentration of her remaining blood, cushioning the impact of any blood loss. The drawn blood hung in a bag from a pole until shortly after the new lung was transplanted, when it was returned to the body.

Dr. Scheinin worked with cool and quiet focus as a soundtrack shuffled from ZZ Top to Bob Seger to Lynyrd Skynyrd. With Ms. Tomczak breathing on a ventilator, he clamped the pulmonary artery and vein, severed them and the bronchus and lifted her diseased lung into a bowl. It was riddled with BB-size nodules, hard to the touch.

After suturing in the new lung with methodical strokes, Dr. Scheinin unclamped the vessels and prodded the organ to inflate like a beach ball. The lung began to rise and fall in precise rhythm.