Guillian- Barre syndrome (GBS) is an acute and fulminant inflammatory polyradiculoneuropathy that presents as progressive weakness of limbs with generalised areflexia or hyporeflexia. Most patients require hospitalisation, and in about 30 % of the cases, ventilator assistance is needed during their illness [1]. Some patients show a quick recovery, while some require prolonged mechanical ventilation (MV) (a requirement for MV for more than two weeks) due to worsening bulbar and respiratory muscle weakness or due to the respiratory complications inherent to prolonged immobility [2]. Previous studies have attempted to identify simple, functional markers to predict prolonged MV, which can help the critical care team plan an early tracheostomy [3,4]. To date, there are no studies in India on patients with GBS on prolonged MV. Here, we aimed to identify the predictive factors determining the duration and outcome of patients with GBS requiring prolonged MV.

This study was conducted in a tertiary care referral hospital over eight years (2009-2018). This was a retrospective and observational study. Any patient with a diagnosis of GBS and requiring mechanical ventilation were included in the study. Those with incomplete data or those who left against medical advice were excluded. The diagnosis of GBS was based on the electrodiagnostic criteria laid by Ho et al. [5]. The demographic data, muscle power grading according to the medical research council (MRC) scale, presence of facial & bulbar weakness and associated co-morbid conditions such as hypertension, diabetes and chronic kidney disease (CKD) were noted. The severity of the disease was assessed by Hughes disability status scale. The MRC sum score was obtained and was stratified into three groups (0-20, 21-40 and 41-60) to compare with the outcome [6]. The ventilator requirement includes the mode {invasive or non-invasive/ continuous positive airway pressure (CPAP), synchronised intermittent mechanical ventilation (SIMV) or assist controlled mode (ACV)}, the duration of ventilation and total duration of hospital stay were noted. The timing and the complications related to percutaneous tracheostomy was noted.

Electrophysiological studies were conducted (by Medtronic key point) at admission, day seven and third week of their illness.

77 years). The average duration of disease was six days (range 0-22 days). The mean admission single breath count was 14, while the mean single breath count at the intubation time was 10. The mean duration of hospital stay from admission was 27 days (3-68 days), while the duration of ventilator requirement from time of intubation was 17 days (1-50 days). Treatment with IVIG or plasma exchange was given within 0-2 days of admission in Hughes grade 4-5. The therapy received was IVIG in 56 patients and PLEX in 22, while one patient did not opt for any treatment due to financial constraints but still improved.

Table 1: Baseline and explanatory parameters of the study population (79 patients).

The baseline parameters of the patients were mentioned as percentages.

The indication of MV was progressive respiratory muscle weakness in 71(90%) patients, followed by pneumonia in 6(8%) and cardiac failure with pulmonary oedema in 2(3%) patients. Only 29(37%) patients needed tracheostomy. Sepsis and septic shock were the parameters that determined the timing of tracheostomy(p<0.01). Neither age, gender, single breath count, facial, bulbar weakness, MRC sum score nor diabetes, hypertension nor smoking indicated a need for tracheostomy. Seventeen (22%) patients had dysautonomia during their hospital stay.

Even the MRC scores of the individual muscles (Table 4) did not correlate with the duration of MV.

Table 3: Association of MRC sum scores (at the peak of the illness) with ventilation duration in study population (N=79)

Abbreviations: MRC¹=Medical research council, ECR²=Extensor carpi radialis TA³=Tibialis anterior

The power of the individual muscle groups did not correlate with the prolonged duration of mechanical ventilation. Twelve (27 %) patients with AMAN, 4(9%) of AMSAN, 22(49%) of patients with AIDP and 7(16%) with unexcitable nerves had received prolonged MV (Table 2). These electrophysiological subtypes did not determine the duration of MV(p=0.612). However, on multivariate regression analysis, sepsis (p=0.02; {95%CI 1.3-24.4}), MRC sum score (p=0.01; {95% CI 0.89-0.99}) and albumin levels within day 14(p=0.004{95% CI 0.05-0.57}) correlated with prolonged duration of MV. Severe weakness in lower MRC sum score (less than 20) predicted high mortality during hospital stay(p=0.007). CKD and pulmonary disease were the other important parameters that predicted significant mortality (p=0.03 and 0.01, respectively). Clinical parameters such as bulbar weakness(p=0.31), single breath count(p=0.76), diabetes(p=0.17), hypertension(p=0.43), smoking(p=0.75) were not statistically significant as predictors of outcome (Table 4).

Table 4: Association of outcome with Demographic parameters of the study population (N=79)

The improvement within six months of follow up did not correlate to their duration of mechanical ventilation (p=0.34).

The number of patients who required MV (35%) was similar to the other studies [11]. The common indicators of MV were respiratory muscle weakness and pneumonia [12,13]. A previous study showed that the combination of single breath count, neck weakness and bulbar symptoms was an excellent bedside predictor of the need for MV [14]. The average single breath count in our study was ten, and it was a significant clinical indicator for intubation.

The defining duration for prolonged mechanical ventilation in critically ill patients is variable, some authors quoting two weeks, three weeks and two months [4,15,16]. Conventionally, we took two weeks, which was felt more practical indicator of the need for tracheostomy. The anticipation of the duration of MV enables the clinician to plan the right time for tracheostomy. Only 37% of the patients underwent tracheostomy, which was a low rate [4]. This difference reflects a practice parameter, allowing an uncomplicated and improving patient to stretch for a few more days rather than performing an early tracheostomy. The significant predictor for tracheostomy was again sepsis, and the complications were rare and hence unlikely to have influenced the outcome.

The most common cause of death in our study was sepsis, septic shock and pneumonia. The mortality in other studies is between 1 -18% [17]. Ours being a tertiary referral hospital, there could have been a possible referral bias. Deaths in these patients occurred predominantly during the critical care unit stay that required intensive ventilator care. Nearly 18% of the patients were still non-ambulatory at six months, similar to other studies (18).

Sepsis and septic shock were 'the' important parameters that determined the duration of mechanical ventilation and the need for tracheostomy. A study from the Netherlands of 150 patients with mechanical ventilation showed that patients with weakness of deltoid muscles with MRC score of 0-2; those with unexcitable nerves or axonopathy on electrophysiology had a greater chance of prolonged duration of MV and probably early tracheostomy might be indicated in them [4].

GBS on electrophysiology, determined the prolonged duration of mechanical ventilation, this study showed the predictors of prolonged duration of mechanical ventilation were sepsis and septic shock. This highlights that GBS has a natural recovery course independent of electrophysiological subtype, and measures should be taken to prevent and treat sepsis.

We acknowledge Dr Meena Angamuthu Kanikannan, who was a constant source of inspiration and support in framing the protocol of the manuscript. Dr SY helped in the proof checking, data collection, literature review, and writing of the manuscript SAJ, Dr MLN, Dr RM, Dr SP, Dr RB helped proofread the manuscript.