Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 2, 2003, pp. 203-205

Neurology India, Vol. 51, No. 2, April-June, 2003, pp. 203-205

Ventilatory management of respiratory failure in patients with severe Guillain-Barré syndrome

A. N. Aggarwal, D. Gupta, V. Lal,* D. Behera, S. K. Jindal, S. Prabhakar*

Departments of Pulmonary Medicine and *Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

S. K. Jindal
Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh-160012, India.
E-mail: skjindal@sancharnet.in

Accepted on 15.04.2002.

Code Number: ni03063

ABSTRACT

Guillain-Barré syndrome (GBS) is the commonest peripheral neuropathy causing ventilatory failure, and 10-30% patients may require respiratory support. Records of 11 adult patients of GBS in respiratory failure, admitted to the Respiratory Intensive Care Unit (RICU) of our institute for mechanical ventilation over a four-year period, were studied. Six patients received intravenous immunoglobulin. The median duration of mechanical ventilation was 38 days. Seven patients underwent tracheostomy. Four patients were ventilated for less than 2 weeks and 3 for more than 2 months each. Seven developed ventilator-associated pneumonia and/or sepsis. Three patients died in, and two shortly after discharge from RICU; all had systemic problems or complications of hospitalization.

Key Words: Acute inflammatory demyelinating polyneuropathy, Ventilatory failure, Mechanical ventilation, Ventilator-associated pneumonia, Sepsis, Hospital mortality.

Guillain-Barré syndrome (GBS) is an acute, monophasic, symmetrically progressive, peripheral neuropathy. The outcome is generally favorable in most patients. Since the disease may be complicated by respiratory paralysis and/or severe autonomic instability, it is recognized as a potential neurologic emergency that may require intensive care management.¹ Respiratory failure is the most life-threatening complication of GBS, and 10-30% patients may require mechanical ventilation.^1,2 GBS is the commonest peripheral neuropathy causing respiratory failure.³ A higher mortality than the West has been seen in the few reports published from this country.^4-6 We review here the ventilatory management of respiratory failure in patients with severe GBS seen at our center.

MATERIAL AND METHODS

Patients of GBS in respiratory failure, admitted to the Respiratory Intensive Care Unit (RICU) of our institute for mechanical ventilation over a four-year period, were managed as per protocol described herein. Diagnosis of GBS was established clinically, and supplemented by data from laboratory and electrophysiologic tests, wherever available.⁷ Age, gender, precipitating events, duration of weakness, baseline symptoms and comorbid conditions were recorded for all patients. The ultimate outcome measure was hospital survival. Duration of mechanical ventilation and ventilator-associated complications (if any) were also recorded.

All patients were ventilated using Puritan Bennett 7200AE ventilators. The need for tracheal intubation and mechanical ventilation was determined by serial assessment of respiratory function by clinical examination (level of overall patient comfort, frequency and depth of breathing, use of accessory muscles, presence of paradoxical respiration, single breath count, and integrity of upper airway reflexes), arterial blood gas (ABG) data and chest radiography.⁸ Initially, control mode ventilation (CMV) with tidal volumes of around 10 ml/kg was used. Patients were quickly shifted to synchronized intermittent mandatory ventilation (SIMV) with pressure support after stabilization. An effort was made to maintain oxygen fraction in inspired air (FiO2) at <0.5, while maintaining adequate oxygenation (pO2 >60 mm Hg). Adequate nutrition, asepsis, humidification of inspired air, and regular endotracheal toileting were ensured. Chest physiotherapy was applied to prevent atelectasis. Continuous monitoring of hemodynamic and respiratory (including ABG and respiratory mechanics) variables was ensured. Patients were frequently turned in bed to prevent pressure sores. Low doses of heparin were administered subcutaneously to decrease risk of venous thrombosis. Immunotherapy with intravenous immunoglobulin (IVIG) was administered wherever feasible, in a dose of 400 mg/kg daily for 5 days.⁹

Tracheostomy was performed in the second week of RICU stay for patients predicted to require prolonged mechanical ventilation.¹⁰ Weaning was accomplished by gradual reduction in the SIMV rate and the level of pressure support. A T-piece trial was given and patients were extubated if they had normal bulbar reflexes and did not show any worsening (as manifested by respiratory muscle fatigue on clinical examination and/or carbon dioxide retention on ABG analysis) during this period.

RESULTS

During the study period, 11 adult patients of GBS required mechanical ventilation in RICU on 12 occasions. There were 8 men and 3 women, with age ranging from 15 to 78 years. Five patients had acute gastroenteritis and one had upper respiratory tract infection just prior to the onset of neuromuscular weakness; in other patients a definite precipitating event could not be identified. One patient had underlying chronic obstructive pulmonary disease and 2 had diabetes mellitus and hypertension at the time of admission. Two patients had already developed aspiration pneumonia by the time they were shifted to RICU, and another required repeat mechanical ventilation after she developed hospital-acquired pneumonia and respiratory muscle fatigue. Four patients had autonomic dysfunction manifested by fluctuations in the heart rate and blood pressure. Six patients received IVIG.

The median duration of mechanical ventilation was 38 days (range 6-160 days). Four patients were ventilated for less than 2 weeks each; of them 2 died during the first week. Other patients underwent tracheostomy during the second week of RICU stay. Three patients (aged 45, 55 and 56 years) were ventilated for more than 2 months.

Three patients developed sacral pressure sores and 7 developed ventilator-associated pneumonia and/or sepsis. In addition, 1 patient developed tracheal stenosis related to prolonged tracheostomy, and needed dilatation (using laser therapy) following discharge. Three patients died in, and two after discharge from, RICU. One 45-year-old man had aspiration pneumonia and sepsis at the time of admission, another 78-year-old man developed sepsis and multiple organ dysfunction soon after admission; both died within the first week of RICU stay. In addition, one 55-year-old man died after 100 days of mechanical ventilation; he had two episodes of ventilator-associated pneumonia and sepsis which responded to antibiotic therapy, but he developed refractory hypotension and renal failure preterminally. One 56-year-old lady, who was ventilated on two occasions for 60 and 38 days, died in the hospital two weeks after successful weaning and transfer to ward. Another patient, who was ventilated for more than 5 months, had a sudden death (possibly related to a cardiac event) at home, 4 days after discharge from the hospital.

DISCUSSION

Adequate ventilation in any individual relies on the triad of adequate inspiratory effort, effective expiratory force, and the ability to protect the airway. All these 3 components may be affected to some degree in patients with GBS.³ Ineffective inspiration is a manifestation of diaphragmatic weakness and results in alveolar hypoventilation. Expiratory weakness results from intercostal and abdominal muscle weakness, and results in impaired cough and clearance of airway secretions. Bulbar weakness increases the risk of aspiration. In addition, weakness of the tongue and pharyngeal muscles may cause positional mechanical airway obstruction. All these mechanisms exert their detrimental effects through a common mechanism of atelectasis, pneumonia and hypoxemia to precipitate acute ventilatory failure. Respiratory function may be compromised much before signs of ventilatory insufficiency are obvious, and serial assessment of ventilatory parameters is mandatory to determine the need for endotracheal intubation and mechanical ventilation.⁸ Vital capacity below 15 mL/kg, peak inspiratory pressures less than 25 cm H2O, inability to count to 20 in one breath, bulbar weakness, paradoxical breathing, hypoxemia and respiratory acidosis are all indications for endotracheal intubation and mechanical ventilation.¹¹ However, no patient should be denied respiratory support because he or she does not meet specific guidelines for measures of pulmonary function. It is prudent to intubate patients electively before a crisis ensues. ¹¹

Patients with GBS have normal lung mechanics and oxygen requirements. Therefore mechanical ventilation itself is not difficult unless pulmonary complications supervene. However, in keeping with the protracted course of GBS, the duration of mechanical ventilation is usually prolonged, with a mean of 4-12 weeks in different reports.^5,6,12-14 The median duration of mechanical ventilation in our patients was 38 days. Three patients required respiratory support for more than 2 months; all were more than 45 years old. There are some data to suggest that older patients require mechanical ventilation for longer periods,¹⁵ though this is not a consistent phenomenon.² What is obvious is that this disease requires longer periods of respiratory support than any other single entity now commonly seen. When profound weakness leads to an almost complete cessation of respiratory muscle function, respiratory support is best provided through CMV.³ The commonest mode of mechanical ventilation used in other patients with GBS is SIMV. This mode is comfortable for the patient, assures a minimum level of minute ventilation, and allows variation in respiratory support from near total to minimal. Pressure support ventilation is often combined with SIMV to reduce work of breathing during spontaneous breaths and minimize desynchronization with the ventilator.

The time to wean patients from mechanical ventilation is when criteria necessitating respiratory support are no longer present. The process of weaning a patient with GBS is best considered as a respiratory conditioning program. As muscle strength improves, gradual reduction in either the SIMV rate or the level of pressure support will progressively increase patient contribution towards the work of breathing. However, several patients cannot be weaned from mechanical ventilation despite satisfactory measurements of respiratory muscle strength. This may be attributed to unappreciated residual diaphragmatic weakness, abnormal coordination of respiratory muscles due to autonomic neuropathy, or systemic factors like malnutrition, fever and depletion of potassium, phosphate or magnesium.³ A subgroup of patients may require prolonged respiratory support, sometimes in excess of one year, before weaning from ventilatory support is possible.¹⁶

Endotracheal intubation is more difficult in patients with GBS than in other patients requiring emergency airway control, because of dysautonomia which can cause sudden arrhythmia or hypotension during airway manipulation.³ Endotracheal tubes currently available require low cuff pressures to maintain adequate seal. Yet, prolonged intubation has its own risks, and it is reasonable to proceed to tracheostomy once the need for prolonged mechanical ventilation is apparent. Early tracheostomy is not routinely advised, since several patients improve rapidly and can be extubated after the first few days.¹⁴ However, patients of severe GBS with clinical and electromyographic evidence of axonal involvement usually require prolonged respiratory support, and tracheostomy can be performed early in this subgroup of patients.³ In all other patients with evolving illness, tracheostomy should be considered in the second week.¹⁰

Complications in critically ill patients with GBS are most often not related to the basic disease. Although autonomic instability can precipitate swings in blood pressure or arrhythmias, these can usually be successfully tackled in a well-equipped ICU. Three of our patients had labile blood pressures requiring definitive therapy. The common complications are related to prolonged intubation and include tracheal stenosis, hemorrhage from innominate artery, cuff leaks, accidental extubation and airway obstruction. In addition, ventilator-associated pneumonia is a constant risk in patients whose normal airway defenses have been bypassed; this risk increases progressively as the duration of intubation increases. Other nosocomial infections, including urinary tract infections and infections through intravenous access lines, are also a common occurrence. Even with meticulous care, several of these complications cannot be prevented in a patient requiring prolonged mechanical ventilation. Some of these complications were also noted in our patients. Once such problems supervene, further management and prognosis are guided more by these complications than the basic disease. These complications are often responsible for increased morbidity, prolongation of the duration of respiratory support and/or adverse outcome.

Deaths resulting from GBS are nowadays uncommon, because of advances in all the aspects of intensive care. Mortality rates vary widely, ranging from 1% to 18% in most reports from the West.¹¹ Patients requiring mechanical ventilation may have higher mortality rates.³ A much higher mortality rate has been reported from some Indian centers, possibly related to less than ideal intensive care facilities due to financial constraints, when compared to conditions in developed countries.^4-6 In the modern era, death in GBS usually results from pneumonia, sepsis, adult respiratory distress syndrome, and less frequently, from autonomic instability or pulmonary embolism; most of these patients are on ventilatory support.^17,18 Old age and associated comorbidities increase the risk of death.¹⁹ Of the 6 patients aged 45 years or more managed by us, 5 died.

In conclusion, ventilatory failure in severe GBS often requires prolonged respiratory support and RICU care. Mechanical ventilation itself is not difficult in these patients with normal lung mechanics and gas exchange. Most patients have a favorable outcome. Mortality is usually related to systemic problems or complications of hospitalization, rather than the basic disease.

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