By Dr. John McElligott
Special to Land Line
To understand high blood pressure, which is also called hypertension, you need to understand “plumbing.” Let me explain.
The body has a pump, the heart. The body also has pipes or hoses, which are the blood vessels known as arteries. Water and blood go through the pumps and pipes.
Increase the pump rate, and the pressure in the pump and pipes goes up. Decrease the diameter of the pipes (constrict the arteries), and the pressure in the pump and pipes goes up. Increase the amount of fluid in the pipes, and the pressure in the pump and pipes goes up.
When the pressure remains high, the pump fails and pipes burst. As the pump slowly stops working, the fluid in the pump slows its flow and stagnates, leaking out of the pipes as the total plumbing system fails.
You are affecting the dynamics of the pump, pipes and fluid when you get stressed or angry; when you smoke, dip or chew; or when you eat or use salt in excess.
Knowing your numbers is vital to understanding what pressure would be best for all the parts of the system. So what does a blood pressure of 120/80, 140/90 or 160/100 mean?
The upper number, or systolic reading, reflects the pressure needed to force blood from the heart out into the body and the great vessels going to the brain and other organs. The brain is more sensitive to high systolic blood pressure. High systolic pressures cause strokes.
The lower number, or diastolic reading, is the pressure that flows in a backward direction when the heart has finished contracting. Diastolic pressure needs to be lower to prevent damage to the heart vessels or coronary arteries.
Drivers need to know which medications are good for treating high blood pressure and how they work in the body.
Some common names for diuretics, or fluid pills, are hydrochlorothiazide (HCTZ), furosamide (Lasix) and diazide (HCTZ/Triamterene).
Fluid pills decrease the fluid pumped by the heart and the amount of fluid in the blood vessels.
However, not all diuretics are good for truckers. Some diuretics are very strong and will make you stop every 30 minutes to urinate. The urine flow problem can take several weeks to resolve.
In addition, these diuretics, with the exception of diazide, can cause a serious loss of potassium. Small shifts up or down in this electrolyte can cause problems; therefore, some diuretics require potassium supplementation. The other most common side effects are cramping, pain over your parotid glands and dry mouth.
Having said this, HCTZ can be a great medication in low doses. The combination of HCTZ with other hypertensive medications can control blood pressure and is excellent for truckers.
ACE inhibitors and ARBs
The next class of high blood pressure medications is ACE inhibitors. ACE is short for angiotensin-converting enzyme, which is a potent substance released from the kidneys to regulate the flow and pressure through the renal arteries. As blood flows through, it is filtered and urine is made.
If a person has narrowing of the arteries to either kidney, then ACE drugs are not indicated because they can cause elevations in electrolytes such as potassium, which can stop the heart dead in its tracks. This is why your doctor will check your blood work before and after starting an ACE drug.
Ace inhibitors and their close cousins ARBs (angiotensin-receptor blockers) are the drugs of choice for a driver with high blood pressure and diabetes. Both of these drugs protect the kidneys from the complications of these devastating diseases. These drugs help keep the arteries soft and compliant and aid in preventing the hardening of these vessels.
ACE inhibitors and ARBs are often combined with HCTZ, and the combination does not require potassium replacement as do pure diuretics. Make sure you ask questions if your doctor gives you a potassium supplement with an ACE/ARB type drug.
Beta blockers and
calcium channel blockers
The heart acts as a pump, propelling the blood through the arteries and veins (the pipes). One way to lower the blood pressure is to lower the number of contractions or beats the heart makes in one minute. The faster rate results in a higher volume of blood being pumped, and results in a higher blood pressure.
Beta blockers lower the heart rate by blocking the stimulating action of adrenaline on the nerve endings in the heart, which results in the heart beating faster. Beta blockers help maintain a slower heart rate, and the blood pressure is subsequently lowered.
You need to be aware of any medical conditions that are not compatible with the medications, which could cause problems. Beta blockers should not be combined with certain conditions – or should be given very cautiously. Those conditions include depression, heart failure, asthma, emphysema, severe insulin-dependent diabetes with frequent episodes of hypoglycemia or blackouts, and some lipid or cholesterol disorders.
Some beneficial side effects of beta blockers include less anxiety, clear thinking, fewer headaches and, in general, a calming effect.
Some unpleasant side effects include increased sleepiness, depressed mood, slowed heart rate that can result in dizziness or blackout spells, poor sex drive and difficulty maintaining an erection.
Beta blocker medications can be a good choice for professional drivers, but they should be tailored to the needs of the specific individual.
The calcium channel blockers are my least favorite class of drug for the driver. Unfortunately, the calcium channel blockers do not seem to work well for some people. In addition, they can cause swelling of the legs and constipation, which are particularly unpleasant side effects for drivers.
Central-acting drugs make the central nervous system relax the blood vessels. The central-acting drugs are not recommended for drivers because they can make one sleepy and can cause blackouts. However, clonidine hydrochloride (Catapres) is used for the emergency treatment of extremely elevated blood pressure when there is danger of a massive stroke.
The medication known as terazosin (Hytrin) is an alpha blocker and causes the blood vessels (veins and arteries) to relax and expand, improving blood flow and thus lowering the blood pressure.
This is a good drug for drivers, primarily for men, for other reasons. Terazosin increases the urinary stream and gives a boost to one’s erectile tissues for sexual activity. The only caveat would be to take the medication when going to bed and not in the morning. Terazosin can make one sleepy and can cause dizziness and (rarely) blackouts.
When considering which type of high blood pressure treatment to prescribe, your physician needs to know not only your profession, but also what you can afford. Generic medications are less expensive in some stores and could be an option. LL
Editor’s note: Dr. John McElligott is a co-founder of PDMD, a chain of truck stop medical clinics for truck drivers.