Chronic renal failure and its effects on driving
Chronic renal failure (CRF) is an irreversible process characterised by impaired renal function, with signs and symptoms that characterise uremic syndrome.
The most frequent causes of CRF are diabetic nephropathy, arterial hypertension, glomerulonephritis and renal polycystosis.
Increased levels of urea may make the patient feel unwell and cause anorexia, laxitude, fatigue, vomiting or blunting of mental acuity.
Proteic malnutrition with hypertriglyceridaemia leads to generalised atrophy of the tissues, typical in cases of chronic uremia.
In the advanced stages, dietary salt is retained leading to arterial hypertension with volume overload and congestive heart failure and oedema.
Until the glomerular filtration has reduced to half its normal rate, few changes are seen in blood pH, although mild non-progressive metabolic acidosis can be observed. In moderate CRF, hyperchloraemic acidosis is evident.
As the renal disease progresses, osteodystrophy develops because of abnormalities in the calico-phosphorus and HTP.
From a clinical standpoint, secondary hyperparathyroidism is characterised by bone pain, itching, ischemic necrosis and periarthritis.
In patients with osteomalacia, pain can appear with proximal functional impotency in the limbs, and spontaneous bone fractures.
Pericarditis can be due to the uraemia and produce cardiac tamponade. Pneumonitis and phlebitis are common.
The artherosclerosis is accelerated by the CRI, which is also adversely affected by arterial hypertension, lipid abnormalities, vascular calcifications cause by the secondary hyperparathyroidism, carbohydrate intolerance, diabetes and dialysis.
Even more frequently seen are cardiovascular problems, because the arteriosclerosis is more extensive with earlier onset and manifests with intermittent claudation and gangrene, coronary disease and icthus.
Anaemia is frequent, and abnormalities in coagulation can cause complications due to propensity to bleed, such as digestive haemorrhage.
Neurological abnormalities are common, with paresthesia caused by distally distributed polyneuropathy, both bilateral and symmetrical, a nocturnal burning sensation, restless legs and muscle cramps.
In advanced cases, uremic encephalopathy with asterixis, convulsions and coma can develop.
The most common digestive symptoms are anorexia, constipation, nausea and vomiting. Superficial ulcers of the mucous, peptic ulcers and diviculitis can cause digestive haemorrhage.
Glucose intolerance, uremic pruritis and hemorrhagic spots are also common.
Diabetic patients with advanced CRI present a diminished need for insulin, with a risk of serious hypoglycaemia if the dose is not adjusted.
Diabetic retinopathy is associated with the evolution of nephropathy.
Psychological conditions such as depression, irritability and risk of suicide.
The specific treatment of the complications can improve the acute drop in renal function, but the progression of chronic renal disease is unlikely to be cured by therapy.
The appearance of oliguria, progressive hyperpotassemia and pericarditis indicate a serious situation, although dialysis or kidney transplant can improve the evolution.
Advice on Chronic renal failure
- Patients with slightly decreased renal reserve do not present symptoms and are able to drive.
- Mild to moderate kidney failure can present only vague symptoms, such as nycturia, which will not interfere with driving, except for tiredness for not getting enough rest at night.
- The initial manifestations of uremia are laxitude, fatigue, and impaired mental acuity, which adversely affect the ability to drive, therefore patients should refrain from driving until the specialist has established the correct treatment and the patient is recovering, meaning he can then decide the patient can drive safely again.
- Neuromuscular manifestations such as sudden muscle spasms, peripheral neuropathy with sensory and motor manifestations, muscle spasms and convulsions, adversely affect driving.
- Gastrointestinal symptoms such as nausea, anorexia and stomatitis are continuous and do not interfere with driving, although they do make it uncomfortable and less safe.
- Vomiting is frequent, and can incapacitate the driver. As there is a risk of this, the driver should try to travel with a companion and stay calm, trying to park in a safe place where there is no risk of having an accident until the episode passes.
- The patient should not drive while suffering from episodes of ulcers with digestive haemorrhage and risk for further bleeding, which occur during the advanced stage of the disease.
- Malnutrition with atrophy of the tissues is observed in advanced cases of uremia and precludes driving.
- The patient should not drive while suffering from poorly controlled hypertension or hypertension that could leave to congestive heart disease or leg oedema.
- Pericarditis is common in chronic uremia and means the patient may not drive.
- Nevertheless, in acute uremia, if the pericarditis is reversible, the specialist may give permission to drive if on examining the patient he finds there are no longer any symptoms or lesions.
- Pruritus is an extraordinarily bothersome symptom for some patients, and can be a distraction from driving.
- Patients with osteomalacia and osseous pain that produce proximal functional impotence in the limbs, and so they should not drive.
- Anaemia and abnormalities in coagulation can weaken the driver and vulnerable, with the illness itself causing a greater risk of haemorrhage as well as small blows or knocks. We should warn the patient of these risks, and if the disorder is serious, advise him not to drive.
- Secondary hyperparathyroidism causes osseous pain, pruritis, ischemic necrosis and periarthritis and can limit driving.
- Patients with stable CRI with few symptoms can suffer from acute metabolic or cCRFulatory collapse if they have intercurrent disease and suddenly deteriorate. The patient must not drive until he is stabilized and asymptomatic.
- Patients with diabetic neuropathy who do not adjust their doses of insulin during the evolution of their kidney failure can cause serious episodes of hypoglycaemia, which could mean them completely losing control of the vehicle if they suffer an episode while driving.
- Diabetic retinopathy has a negative effect on the eyesight, meaning it does not meet the legal minimum requirements for driving.
- Doctors should warn all their patients who drive with kidney failure, that a lot of drugs can cause side effects that affect driving if they do not adjust the doses. This is the case with anti-anxiety drugs, antidepressants, anticonvulsants, etc.
- A driver with uncontrolled psychological and depressive conditions should be told not to drive temporarily until the doctor can confirm that his state of mind has improved sufficiently for him to drive again.