Hey gang.  It has been a long time since I have done an "Ask Dr. Rob" post.  That is kind of like saying: "It's been a long time since I have had hemorrhoids."


Well, get out our Preparation H, sit down, and brace yourself for the next installment of this infamous series.

Today's question comes from Luke, who asks:

Dear Dr. Rob:

What's with the temperature of the exam room?  Why is it that every time I go to the doctor I leave with a case of frostbite?  Don't you docs realize that people are taking off their clothes in those rooms??

I was wondering when this question would come up.  Many patients have chattered this question to me, and I relish the chance to set things straight.  There is a good reason for it - a scientific reason.

It's the Law

Physicians aren't keeping the rooms cold out of whim or nastiness, we are following the law.  To be precise, we are following the laws. Yes, the laws that I am talking about are none other than the Laws of Thermodynamics.

einstein_laughingMost people think that there are only three laws of thermodynamics, but there are actually four.  This is because chemists felt that three laws were just not enough for them to relevant to today's kids, so they made a fourth law.  But some chemists were really ticked off at this, and took it to court.  They felt that having a fourth law would make the physicists snicker at them, as physicists are perfectly content having three laws to guide them: Newton's Laws.  The courts upheld their complaint (siting the law of unintended consequences) so instead of having a fourth law, they made the zeroth law. This made the physicists laugh out loud.

Here are the laws of thermodynamics:

  • The Zeroth Law (he he) - If two thermodynamic systems are separately in thermal equilibrium with a third, they are also in thermal equilibrium with each other.
  • The First Law - The change in the internal energy of a closed thermodynamic system is equal to the sum of the amount of heat energy supplied to the system and the work done on the system.
  • The Second Law - The total entropy of any isolated thermodynamic system tends to increase over time, approaching a maximum value.
  • The Third Law - As a system asymptotically approaches absolute zero of temperature all processes virtually cease and the entropy of the system asymptotically approaches a minimum value; also stated as: "the entropy of all systems and of all states of a system is zero at absolute zero" or equivalently "it is impossible to reach the absolute zero of temperature by any finite number of processes".

Does that explain things, Luke?  I thought it wouldn't.  So let me show you how it applies to you when you are wearing that little paper gown that is open in the back.

Zeroth Law: All things being equal...

This law refers to different systems being in equilibrium.  The obvious application for this in medicine is the need for the digestive, cardiovascular, and neurological systems to be in equilibrium.  If these are out of kilter, many bad things can follow.  Here's how:

  • If a person's eyes are bigger than their stomach, the neurological system is in greater power than the gastrointestinal system.  This is a real problem.  It causes the GI tract to seek food in large amounts to stretch the stomach out.  Cooling the eyes to below 40 degrees F makes them shrink - fixing the imbalance and reducing the obesity rate.
  • nm_heartburn_080602_mnIf someone has a warm heart, it puts the cardiovascular system into equilibrium with the gastrointestinal tract.  A cold heart causes the stomach to try to put things back in order by heating the heart.  But the stomach isn't made to warm things, and so usually just causes heartburn.  So doctors are utilizing the physiological phenomenon: "cold hands, warm heart" to prevent this from happening.
  • If someone has a lot of nerve, it means they are not nice to be with.  This is diametrically opposed to someone being all heart. It is important for someone to get up their nerve and also for them to have a heart. To prevent people from having a lot of nerve, it is important to give them cold feet. This makes them lose their nerve - causing the system to get back into equilibrium.  It's really quite obvious.

The First Law: Energy Crisis

0108081342_m_ces08_blackberry_poseThe next law is the first (stop laughing, physicists).  This law is about the internal energy in a closed system. Internal energy is the energy something has inside of itself.  This energy results in work. Patients are not supposed to be doing work while at the doctor's office.  It really annoys me when they are typing on their laptop or staring at their Blackberry.

To prevent this, doctors lower the internal energy in the patient by cooling down the exam room and closing the door (thus making a closed system).  This prevents the patient from working.


The Second Law: Disorderly Conduct

The second law has always been one of my favorites.  Entropy and me are pals.  It means that my desk being messy is simply a natural phenomenon.  It's not ADD, it's entropy!

So what does that have to do with cold exam rooms?  Entropy is a process that is driven by the energy in the system.  Increased heat causes particles to move faster, and hence for disorder to occur faster.  Despite my love of entropy as an excuse, it isn't good in the exam room.  I don't want my tongue depressors in the place where the cotton balls go.  People don't want me putting cotton in their mouths.  I don't want the scalpels to end up where the latex gloves go.  People wouldn't want me to use a scalpel to examine their....uh, never mind.

The gist of it is that it is clearly in the best interest of my patients to decrease the entropy in the exam room.  So, the colder the exam room, the less the entropy.  The less the entropy, the less the disorder.  The less the disorder, the less scalpels get mixed up with latex gloves.

You don't want that scalpel to end up....uh....well...you know.  Trust me: you don't.

The Third Law: The Absolute Truth

Probably the most significant thing about the third law (aside from the fact that it is really the fourth) is that it uses the word asymptotically. This word refers to the idea of an asymptote, which is "a line that continually approaches a given curve but does not meet it at any finite distance" (from the dictionary on my nifty-keen MacBook).  It is kind of like when you are packing to leave for a vacation, and are "almost" packed.  The closer you get to being done, the more time it takes to do any given task; and in the end, it takes two weeks to find your toothbrush.  It happens every time we try to go on vacation.  It is asymptotic.


The point that is being approached in the Third Law is called absolute zero.

Absolut Vodka is made in Russia.  Absolute Zero was discovered in Minnesota.  The people of this fair state discovered that if they got cold enough, then all entropy would be stopped completely.  Reaching absolute zero would make all of their children's rooms be always clean and chaos from a contested election be non-existent.  They keep trying to reach absolute zero, but it gets harder and harder the closer they get.  So, despite their best efforts, their kids still leave the socks on the floor.

The reaction of the Minnesotans is predictable: they run for the Absolut Vodka.  It is my hope, however, that they will one day reach absolute zero.  I think they will find my toothbrush there.

So what does this have to do with exam rooms?  I am not quite sure.  I actually missed that class in medical school.

I was looking for my toothbrush.

The Cold, Hard Facts

So there you have it, Luke.  That's the science behind the arctic blast down the back of that paper gown.  We really have no choice in the matter.  We wouldn't want the thermodynamic police after us.

Before I close, I have to mention one more reason we doctors like to keep the rooms cold.  How else could we keep the stethoscopes cold enough to stick to your skin?  It just wouldn't be right to have a warm stethoscope!

Thanks for the question.

Don't forget to submit your questions to dr.rob.questions(at)gmail(dot)com.