Read More about Blood Clots

Updated 7/5/08

By Brian McGrory

Blood Clots
Arteries are blood vessels that carry blood away from the
heart to body tissues and organs. Veins are blood vessels
through which blood travels from all parts of the body back
to the heart.

A blood clot is a jelly-like mass of thickened blood. The
body normally forms a blood clot to stop bleeding. After hip
surgery there will be a blood clot near the new hip joint.
This is normal, and not dangerous.

If a blood clot develops inside a vein, however, it can
block the normal flow of blood and cause temporary and
long-term problems. This can result in pain, tenderness and
swelling of the leg. When a blood clot occurs in one of the
main veins of the body (usually a leg or pelvic vein after
hip surgery) it is called a deep vein thrombosis or DVT.
These clots become life threatening if they move to the
heart, lungs or brain. If a clot breaks loose from a vein,
it may travel through the heart and can block lung arteries.
This is called a pulmonary embolism or PE. A PE can cause
sharp chest pain, shortness of breath, coughing up blood or
passing out. If the clot is severe enough, it can be life
threatening or fatal.

Methods to prevent blood clot after surgery may include
early mobilization and activity, elevation of the feet,
ankle exercises, elastic stockings, compression devices that
passively help blood flow in the legs, and anti-coagulation
medicines.

PREVENTION OF DEEP VEIN THROMBOSIS (DVT PROPHYLAXIS)

What Are The Issues?

The medical term for a blood clot in the blood vessel is a
thrombus. Deep vein thrombosis (DVT) is a formation of a
blood clot in one of the deep veins of the body,
particularly in the leg or pelvis. It is a problem that can
be asymptomatic (silent), or in the worse case scenario,
fatal. Death can occur if a blood clot which forms in the
deep veins of the body breaks off and travels to the lungs,
heart or brain and causes severe overload of the capacity to
breath or pump blood. Some doctors think that even a silent
blood clot can cause chronic swelling or skin ulcerations, a
difficulty called post-phlebitic syndrome.

The risk of DVT is increased in a number of circumstances.
Lower extremity surgery, and specifically total hip
replacement surgery, increases the risk of deep vein
thrombosis. The surgery heightens the body’s tendency for
coagulation or clotting. In addition, when the leg is
manipulated during surgery there may be irritation to the
walls of the major blood vessels in the leg. Finally, during
and after surgery the lower extremity is not used as much
and, therefore, the normal blood flow rate is decreased. The
leg muscles usually help venous blood return to the heart
when they are used.

Further factors heighten the risk of blood clotting. These
include history of previous DVT or PE, cancer, obesity, and
conditions that predispose to abnormal clotting (for
example, a family history of DVT/PE or known medical
condition associated with increased clotting).

Patients contemplating hip replacement surgery therefore
need to understand the issues regarding what methods should
be used to minimize the chance of deep vein thrombosis.

Why Is There Controversy?

1. There appears to be no known way to absolutely prevent
deep vein thrombosis after total hip replacement surgery.

2. Some prevention strategies actually cause complications
that can be worse than DVT. An example of this would be a
bleeding complication near the spinal cord because the
patient was on a blood thinner medicine.

3. Each of the methods used to diminish risk of DVT has an
associated set of risks and benefits. Issues include the
expense of the intervention, the convenience, and the
ability of a given patient to utilize or comply with their
use.

4. There are multiple treatments to minimize the risk of DVT
and fatal PE.

5. Medical doctors and surgeons often disagree on what is a
more serious complication for the patient and, therefore,
disagree on the exact method to prevent blood clots at the
time of surgery.

6. There appears to be significant marketing by some
companies that may overstate the benefits of a given
intervention and may gloss over some of the problems
associated with that intervention.

7. There are conflicting data as to what is and what is not
helpful in preventing blood clots. Most of the studies
available look at several different factors at once; it is
therefore difficult to understand if a specific intervention
has made a large difference. Examples of this are:

· The NIH has said that aspirin does not help prevent blood
clots after total hip replacement surgery, but there is
evidence that when taken with a global program of
prophylaxis interventions, aspirin is helpful in preventing
blood clots. More than one study has suggested that low dose
aspirin reduced the risks of PE and DVT in high-risk
surgical patients. This was confirmed in a recent clinical
trial in which 160 mg of aspirin was given for 35 days after
surgery.

· Research studying DVT and PE is a “moving target.” As we
change the specifics of a given type of surgery (including
the type of anesthesia and the activity after the surgery),
research data from surgeries done as recently as 5-10 years
ago may not be applicable to surgery done today.

· One of the blood thinners that is commonly given, sodium
warfarin (Coumadin), can be given at many different dosages.
Depending on the specific amount given and the response of
individual patients to that dose (monitored by a blood test
called the INR), the protection from DVT and PE may be
different for different patients.

· Some of the newer injectable anti-coagulant medicines were
originally approved (and are argued to be as good or better
than Coumadin) if given at the time of surgery or slightly
before. Some of the companies have decided that these
medicines should be given slightly later, however, because
of a significant rate of bleeding complications. This,
however, makes it unclear if they are helpful to the same
degree that was noted when they were given at the time of
surgery. One of these bleeding problems may occur when
giving spinal anesthetics in patients that have been taking
these medications (when spinal anesthesia is used with low
molecular weight heparin drugs or heparinoids, bleeding next
to the spine can occur and can result in long term or
permanent paralysis).

· The actual rate of deep vein thrombosis is difficult to
assess, as most physicians do not obtain venograms or other
invasive or non-invasive tests to screen for blood clots on
all patients.

· The type of anesthesia, operative time and blood loss are
also important in determining the risk of deep vein
thrombosis and, therefore, must be entered into the equation
discussing these issues.

What Do Most Surgeons Do

Eighty-six members of the hip and knee societies in North
America were surveyed to determine what they do after total
hip replacement to minimize the chance of blood clots.

All surgeons responding used some type of prophylaxis.
Sixty-four percent of the time warfarin was used, fifteen
percent of the time low molecular weight heparin was used,
and twenty-one percent of the time aspirin was used. Ten
percent of surgeons gave intra-operative heparin during
their surgeries in addition to one of these other regimens.

Mechanical DVT prophylaxis, such as compression stockings,
were used in 76% of cases in addition to one of the
medicines.

Medicines were continued less than two weeks in 38% of those
responding, between two and four weeks in 29% of those
responding, and greater than four weeks in 33% of those
responding. Perioperative testing with a method such as an
ultrasound was performed routinely 22% of the time, only in
symptomatic patients in 71% of the time, and never used in
7% of the time.

What I Do

Because there is no absolute way to prevent deep vein
thrombosis in a small amount of patients after hip
replacement surgery, my philosophy is to minimize the chance
of blood clot while also minimizing the inconvenience and
expense to the patient.

I think that it is important to differentiate between
patients at standard risk of DVT after hip replacement
surgery and those at very high risk of blood clot, as I
treat them differently.

In those patients at standard risk, I initiate blood thinner
medicine the day of surgery by having the hospital staff
give the patient warfarin on the morning of surgery. During
the surgery I use a hypotensive spinal anesthetic if
possible, and minimize blood loss and operative time. The
patient is wearing a thigh-high TED stocking on the
contralateral leg during the surgery, and a thigh-high TED
stocking is placed on the operative leg immediately after
surgery. In the recovery room the patient is instructed to
do ankle pumps as soon as the spinal anesthetic wears off,
and this is encouraged throughout the hospital stay. The
morning after surgery the patient stands by the bedside and
does toe pumping exercises. Physical and occupational
therapy are initiated with the goal of maximizing muscle use
(even if the patient is not bearing full weight on the
operative leg). INR is monitored throughout the
hospitalization, and each day the patient is given a dose of
warfarin to try to obtain an INR between 1.7 and 2.0. Once
this is achieved, this level of anti-coagulation is
continued for between 7 and 10 days. The patient continues
to wear the thigh-high TED stockings during this period, and
continues leg elevation and ankle pumping when appropriate.
The patient takes 160 mg of aspirin per day after the
warfarin treatment is completed and this is continued for a
minimum of 35 days. Aspirin and warfarin are usually not
given together because an increase in bleeding episodes can
be seen when combination therapy is given. Discontinuation
of the thigh-high TED stockings depends on the swelling any
given patient experiences, but are usually worn for 2 –6
weeks.

We are vigilant throughout the perioperative periodto
monitor for the signs and symptoms of deep vein thrombosis
and pulmonary embolus. If any of these signs are present,
consideration of an ultrasound test or, if necessary, a lung
scan may be the next appropriate step.

In patients with very high risk of blood clot, warfarin
therapy is continued for 6 to 12 weeks after surgery. A
higher INR (between 2 and 2.5) is usually achieved, and
aspirin is not routinely given. Once or twice a week the INR
is measured with a blood test. All other aspects of the
program are similar in this group.

Discharge Instructions to Prevent DVT

· Take several short walks each day

· Do ankle pump exercises every hour while awake

· Wear the TED stockings while sitting and standing. You may
(with help) take them off when in bed, but your legs should
be elevated on one or two pillows. At the 2 week follow-up
you will get further instructions on how long to wear the
stockings.

· If you go to the rehabilitation hospital or nursing home:

·You will be given blood thinner by your nurses.

·You should take 160 mg aspirin each day for 35 days after
you are discharged.

· If you are discharged to home:

·You will be given a prescription for warfarin, also known
as Coumadin, which you should take until empty (there are no
refills).

·You should take 160 mg aspirin each day for 35 days after
you have finished your warfarin.

· If we know that you are at very high risk of blood clot,
the team will tell you and give you special medicine
instructions

· If you have leg swelling that gets worse during the day,
but that is minimal in the morning, take 3 twenty minute
rests during the day. During the rests you should lay
completely flat with 2 to 3 pillows under both of the feet.

· Call the office immediately if you think that you have
signs or symptoms of DVT, PE, or excessive bleeding.

Deep Vein Thrombosis
Pulmonary Embolism
Excessive Bleeding

Increasing leg pain
Shortness of breath
Excessive bleeding after shaving

Swelling that does not decrease with leg elevation
Chest pain that may be worse with deep breaths
Bleeding from the gums

Enlargement of the veins near the skin surface
Coughing up blood
Black or red stool

Reddish skin color
Rapid heart beat

Skin that is warm to the touch
Feeling faint

What You Should Ask

It is important for the patient considering hip replacement
surgery to understand:

1. That there is a risk of deep vein thrombosis.

2. Some patients are at an even higher risk and may need to
be treated differently than patients under the standard
risk.

It is important to discuss with your surgeon what he or she
suggests to minimize the chance of deep vein thrombosis and
pulmonary embolus after your hip surgery. In my opinion, all
patients undergoing hip replacement surgery should
understand the pros and cons of the different treatments to
prevent these complications, and the surgeon should have a
well thought out plan for minimizing the risk of deep vein
thrombosis.