Winter 2004

Management of GBS in the intensive care unit

Most patients with Guillain-Barré syndrome (GBS) require admission to an intensive care unit (ICU) under the care of physicians who are familiar with the medical complications that develop in paralyzed ICU patients. The timely and skillful management of medical problems is as important as immune therapy in the outcome of patients with GBS.

Disordered breathing, manifest as weakness of the diaphragm and accessory breathing muscles, is a central issue and should be anticipated in any GBS patient with progressive limb weakness or speech and swallowing difficulties. Mild collapse of lung tissue (termed atelectasis) develops early in GBS and leads to lower oxygen levels. High carbon dioxide levels is a later finding as ventilatory failure advances; therefore, oxygen levels are not as helpful as measuring the strength of the breathing muscles at the bedside (respiratory mechanics) in monitoring the evolution of diaphragmatic weakness in GBS patients. Vital capacity, tidal volume, and negative inspiratory force are reasonably sensitive reflections of diaphragmatic power, and progressive decline in these values indicates impending breathing failure and the need for ventilatory support. These measures should be obtained early on in the course and repeated as frequently as dictated by the clinical state (up to every 4 to 6 hours). In general, the need for assisted breathing with ventilator support is advised if the vital capacity drops below approximately 14 ml/kg, but it must be acknowledged that this is a guideline and other factors such as age, lung disease, risk of choking, and perhaps most immediately, the degree of fatigue as evidenced by excessive perspiration, increased breaths per minute, and increased heart rate. If the breathing values remain stable (vital capacity above 1.5 L and inspiratory force better than -40 cm H20, approximately) for several consecutive measurements, the frequency of these measurements can be reduced.

Incentive spirometry (forceful breathing into a handheld plastic tube) is useful in the early stages of the illnesses prevent atelectasis. Frequent sectioning and chest physiotherapy minimize the accumulation of saliva and prevent choking and pneumonia, but patients with trouble swallowing will probably require intubation for protection of the airway. Most patients with severe, ventilator-dependent GBS who have no improvement after several weeks require tracheostomy to secure long-term airway management, avoid narrowing of the trachea as a complication of the endotracheal tube (tracheal stenosis), facilitate sectioning, and maximize patient comfort. Older patients with preexisting pulmonary disease are more likely to require tracheotomy.

Many patients with GBS have problems related to the automatic functions of the body, such as maintaining a normal heart rate, blood pressure, and bowel and bladder function. These abnormalities are referred to as ''dysautonomia,'' and involve demyelination of the autonomic nerves that develop as a complication of GBS. Autonomic dysfunction is often self-limited and thus may require no specific intervention. For example, resting increased heart rate (tachycardia) is common in GBS patients and does not require treatment except in those with active coronary artery disease and acute lack of blood flow to the heart. Hypertension often develops as a consequence of a procedure (for example, sectioning or intravenous catheter placement) but is usually transient and does not require therapy. Sustained high blood pressure (for example, > 180/95) can be managed with medications. Conversely, sudden drops in blood pressure with position change, termed postural hypotension, is often precipitated by only minor position changes and can be effectively treated with intravenous fluids or by placing the patient in the flat position. Invasive procedures or certain types of medications may trigger excessive autonomic nerve discharges (''vagal spells”) and precipitate slowing of the heart rate or other cardiac arrhythmias. These episodes are usually transient but anti-arrhythmic medications or a temporary cardiac pacemaker may be necessary. Difficulty with emptying of the bladder is common and of can be managed with intermittent catheterization or a temporary indwelling bladder catheter.

Infection is probably the most common medical complication that develops in GBS patients in the ICU. The major sources of infection are the lungs, urinary tract, and central intravenous catheters. Infections of the trachea or sinuses are other considerations in patients who are on a ventilator and have a persistent fever with no apparent source of infection. Every effort should be made to identify the bacteria and thus guide appropriate antibiotic therapy. Routine monitoring of the chest x-ray and sputum and urine cultures are useful, but bacterial colonization occurs frequently and patients should receive antibiotic therapy only when there is clinical evidence of an infection; inappropriate treatment with antibiotics only increases the risk of infection with antibiotic-resistant bacteria. Although indwelling urinary catheters are often necessary in GBS patients, the risk of colonization and infection increases after several days.

Immobilization that is associated with GBS predisposes to the formation of clots in the legs (deep venous thrombosis), which can break off and travel to the blood vessels of the lungs (pulmonary embolism). Daily skin injections of heparin and compression boots around the legs and thighs should be used routinely to prevent such clots from forming, and chronic thinning of the blood with warfarin may be considered for those who are bedbound or ventilator-dependent for long periods. Although ''plugging'' of the airways with mucous is probably the most common cause of sudden worsening of breathing in ventilated patients with GBS, any unexplained episode of acute oxygen loss requires evaluation for pulmonary embolism.

Patients who are on ventilators or have trouble swallowing require feeding through a small, thin tube that is placed in the nose which leads down to the stomach (nasogastric tube feeds) to maintain long-term nutritional support. A feeding tube can be placed directly into the stomach (gastrostomy tube) at the time of tracheotomy in patients who have a prolonged recovery. Feeding through an intravenous catheter (termed hyperalimentation) may be necessary in patients who have reduced bowel function. Careful intravenous hydration is essential because fluid losses that occur from perspiration and ventilator support may be substantial, leading to dehydration and impairing heart rate or blood pressure control. Electrolyte abnormalities (especially a low serum sodium level) also may develop.

Pain is a common symptom in patients with GBS, and is often underappreciated by the medical staff. Narcotics are almost always needed to manage pain, and the use of non-narcotic, chronic pain-killers often provides additional relief. An excellent alternative that we use routinely for severe pain in the back or legs is epidural analgesia; pain medications can be administered through a catheter that is placed near the nerves in the lower spine. Most patients benefit from early physical and occupational therapy. For example, passive range of motion of paralyzed joints prevents contractures, foot boards minimize the risk of foot drop and shortening of the Achilles tendon, and frequent turning and air mattresses reduce the risk of skin breakdown and development of skin ulcers.

Symptoms of anxiety and depression are also common, occur at all stages of the illness, and should not be overlooked. Those who are paralyzed on a ventilator and unable to communicate with their caregivers are most likely to experience fear and helplessness. Communication boards allow patients to maintain a ''connection'' with their families, nurses, and medical staff. We have observed that contact with recovered GBS patients provides additional psychological support.