Your Oct. 15 edition contains two items challenging the factual accuracy of my biography "Dutch: A Memoir of Ronald Reagan."

Permit me to respond first to the letter of Drs. Joseph M. Giordano and John E. Hutton Jr. regarding the medical care delivered to President Reagan after the assassination attempt of March 30, 1981.

My statement that catheters were inserted into Reagan's "arterial lines" was an error, and the phrase has already been altered to "veins" for the next printing. As for the number of chest tubes inserted into his chest, it is given as two in Dr. Herbert L. Abrams's authoritative history of the assassination attempt and its aftermath, "The President Has Been Shot." But since Giordano says that he personally inserted only the first of these (for blood drainage) and not the second (for air retrieval), I will adjust my text accordingly.

I also stand corrected on the matter of the president's total blood loss "being suppressed for a long time." It was confirmed by George Washington University Medical Center at 3.7 quarts on April 2, 1981. This confirmation, however, itself corrected the hospital's initial statement that he had lost only 2.5 quarts. To this day, many Americans are unaware how near death Reagan was. Abrams devotes two scorching chapters to the efforts of both the hospital and the White House to play down the crisis and exaggerate the speed of Reagan's recovery. He finds without equivocation that the 25th Amendment should have been invoked to relieve a temporarily incapacitated president from executive responsibility.

When I wrote that during the initial moments of the emergency, Reagan's "obstinate heart still beat on, lowering the pressure still further," I was stating a simple hydraulic fact. It was pumping blood out of his vascular system and into his pleural cavity--hardly part of the normal pressurized circuit. Giordano has himself publicly confirmed that Reagan "had a blood pressure of 70/0; they couldn't [read] it in the normal ways. . . . Another five or ten minutes and he may have been at the point of no return." In the light of this, it is disingenuous for him and Hutton to suggest that the ashen-faced president was maintaining normal pressure before reperfusion.

They further challenge my assertion that the emergency room blood transfusion amounted to "a major physiological insult" to Reagan's system. This is the language of Dr. Benjamin Aaron, chief operating surgeon in the emergency. Aaron also informed me that certain units of the replacement blood and plasma frantically squeezed into the president were older and colder than they should have been in ideal conditions. He may have said "refrigerator" in describing the storage process to me, although my notes of our interview say "freezer." In any case, neither noun affects his conclusion that the president suffered a vascular shock "of number ten magnitude, worse than a prolonged beating."

The careful language wherewith Giordano and Hutton declare that "by the time [cold] blood is administered through IV lines, the effect on core body temperature would probably be small" contrasts with Aaron's admirable willingness to call a spade a spade. I quote from the American College of Surgeons' guidelines for advance trauma life support, sent to me by Hutton himself: "Iatrogenic hypothermia in the resuscitation phase of trauma victims can and must be prevented. The use of blood warmers is . . . most desirable in the emergency department. The most efficient and easy way to prevent hypothermia in any patient receiving massive amounts of crystalloid is to heat the fluid to 39 degrees C before using it."

Notwithstanding these items of contention, I would like to emphasize my belief that Giordano and his emergency room team--acting as fast as they could and as professionally as they could--deserve as much credit as Aaron and his surgical team for saving the life of the president.

On the final point Giordano and Hutton raise, regarding the normality of Reagan's blood profile, they are contradicted by Aaron, who told me that his count was still "below normal" in 1989. And their claim that the president's recovery after each of his subsequent hospitalizations was "extraordinarily rapid" is somewhat belied by the fact that in late February 1987, seven weeks after his prostatectomy, aides were worried enough to again consider invoking the 25th Amendment.

Elsewhere in your Oct. 15 issue, Charles Krauthammer alleges in his column "Nixon on the Couch" [op-ed] that seven pages of my book are devoted to "imagining Reagan's thoughts while making his first movie." The thoughts referred to are not imagined. Those of Ronald Reagan the man are taken from his own written account of the production, and those of "Andy McCaine," the onscreen hero, derive directly from the shooting script of "Love Is on the Air." Both sources are repeatedly cited in the notes.

Since Krauthammer is--as he often reminds us--a psychiatrist, he must be aware of the phenomenon whereby an actor's personality sometimes melds with that of his character. I confess that I am more interested in such subtleties than in the oft-told story of Reagan's 1980 presidential campaign, which is already well-documented in the works of Lou Cannon and others.

--Edmund Morris