INTRODUCTION

 

In the acute stage of the stroke, dysphagia is found in up to 50% of stroke patients, depending on the timing of the assessment, the diagnostic methods used.¹ Dysphagic symptoms resolve in most patients within a week to a month and persist in only a small number of subjects beyond six months.² Aspiration pneumonia is the most important acute complication of dysphagia, affecting up to one third of dysphagic patients.³

 

Aim of Work

To estimate the frequency of pneumonia in acute stroke patients fed by nasogastric tubes and to determine risk factors for post stroke pneumonia.

 

PATIENTS AND METHODS

 

Fifty patients (27 male, 23 female) were consecutively admitted to neurology critical care unit, Zagazig university hospitals. Their ages ranged from 50 to 72 years with a mean age 62±10.4 years.

The study was approved by local ethics committee. The clinical severity of the stroke was assessed on the day of admission using the National Institutes of Health stroke scale (NIHSS).

We included patients presented within 24 hours of the onset of acute stroke and patients provided with

a nasogastric tube (NGT) because of dysphagia. On the other hand, we excluded patients who were admitted for more than 24 hours after stroke onset, patients who started oral feeding from the first day of admission and those who were in coma or with endotracheal intubation on admission.

All patients were subjected to (a) full history taking, (b) general and neurological examination, and (c) computed tomography (CT) or magnetic resonance imaging (MRI) to confirm the diagnosis of stroke.

The patients’ ability to swallow was assessed clinically on the day of admission using two of the following standardized tests. First, the swallowing provocation test. This test is generally used to evaluate the swallowing reflex. The test requires the injection of 0.4 ml (first step) and, if necessary, 2.0 ml (second step) of distilled water into the nasopharynx through a small nasal catheter. This test was considered normal if the latency of swallowing after either of the water injections was less than three seconds.^4,5 Second, the water swallowing test that assess the patient’s ability to drink 5 ml (first step) and 50 ml (second step) of water.⁶ Subjects who drank the water without cough or wet/hoarse voice were considered normal.

On the day of admission, a nasogastric tube (flexible silicon tube with inner diameter of either 14 mm or 16 mm) was inserted only in patients in whom either of the above tests yielded abnormal results. The indication for tube feeding was re-evaluated daily. We noted the time when the nasogastric tube was removed and oral feeding was started.

 

The patients were examined daily throughout their hospital stay for the presence of pneumonia. The diagnosis was based on three or more of the following variables; fever, productive cough with purulent sputum, abnormal respiratory examination (tachypnea > 22 breaths/min), tachycardia, inspiratory crackles, bronchial breathing), abnormal chest radiograph, arterial hypoxemia (PO2 <9.3 kPa) and isolation of a relevant pathogen.

 

Statistical Analysis

All other analyses were performed using a statistical software package (SPSS for Windows version 10.0; SPSS Inc., Chicago, IL). Comparisons of the categorical variables were made using the Chi-square test. Continuous variables were compared among groups using the Student’s t-test. We took p value at or below 0.05 to indicate significance.

 

RESULTS

 

No statistically significant difference between patients with pneumonia and those without pneumonia regarding the age and sex, and regarding the lesion location (Tables 1 and 2).

As measured by the NIHSS score, patients who acquired pneumonia were more severely affected than patients without pneumonia. This difference was statistically significant. Moreover, Patients with pneumonia more often required endotracheal intubation and mechanical ventilation as well as longer duration of NGT insertion than those without pneumonia. This difference was also statistically significant (Table 3).

Patients with pneumonia more often had disordered consciousness and facial palsy than those without pneumonia. The difference was statistically significant (Table 3).

 

 

Table 1. Epidemiological data in relation to development of pneumonia.

 

	No  pneumonia (n=28)	Pneumonia (n=22)	P-value
Age (years±SD)	65.5±10.4	68±11.5	0.42
Sex Males Females	16 (57.2%) 12 (42.8%)	11 (50%) 11 (50%)	0.61

 

 Table 2. Lesion location in relation to development of pneumonia.

 

	No pneumonia (n=28)	Pneumonia (n=22)	P-value
Right MCA occlusion	7 (25%)	5 (22.7%)	0.85
Left MCA occlusion	14 (50%)	10 (45.5%)	0.75
Brain stem	2 (7.2%)	1 (4.5%)	1.0
Right capsular hemorrhage	2 (7.2%)	3 (13.6%)	0.64
Left capsular hemorrhage	3 (10.7%)	3 (13.6%)	1.0

MCA middle cerebral artery

 

Table 3. Clinical features in relation to development of pneumonia.

 

Clinical features	No pneumonia (n=28)	Pneumonia (n=22)	P-value
NIHSS score ± SD	10.5±5.2	17.8±4.9	0.000**
Decreased   consciousness	5 (17.9% )	13 (59.1%)	0.002**
hemiparesis	10 (35.7%)	13 (59.1%)	0.09
Facial palsy	9 (32.2%)	14 (63.6%)	0.02*
Dysarthria	6 (21.4% )	7 (31.8%)	0.4
Aphasia	7 (25% )	10 (45.5% )	0.13
Neglect	4 (14.3% )	4 (18.2% )	0.35
Endotracheal intubation	3 (10.7% )	8 (36.4% )	0.04*
Duration NGT insertion (days±SD)	5.5±1.5	17.3±2.5	0.000**

NGT nasogastric tube, NIHSS National Institute Health Stroke Scale

*Significant at P<0.05 **Significant at P<0.01

 

DISCUSSION

 

Over a 12-months period, a prospective study was done on 50 consecutive patients with acute stroke who were given tube feeding because of dysphagia. The incidence of pneumonia in our patients was 44%. This number seems surprisingly large compared with other studies. Thus, Mann and colleagues¹, Gordon and colleagues⁷, and Hilker and colleagues⁸, found evidence of pneumonia in only 20%, 13%, and 21% of their patients, respectively. Discrepancies between these numbers are clearly explained by selection bias, as the frequencies given in the first three studies referred to unselected stroke patients.

In our study, a decreased level of consciousness and facial palsy were independent clinical variables predictive of pneumonia. Disordered consciousness has already been identified as a major risk factor for pneumonia, and is not specific for stroke patients.⁹ Pathophysiologically, a decreased level of consciousness is known to lead to attenuation of protective reflexes and to worsening of the coordination of breathing and swallowing¹⁰, thereby predisposing to aspiration independent of the underlying disease.

Facial palsy itself does not increase the risk of aspiration. More probably, a severe facial palsy indicates concomitant paresis of the tongue and other oropharyngeal muscles involved in swallowing. Severe facial palsy can be interpreted as a marker for a substantially increased risk of aspiration.¹¹

The incidence of pneumonia in acute stroke patients fed by nasogastric tube in our study (44%) warrants changes to the present therapeutic strategies.

The early insertion of a gastrostomy tube does not appear to be superior to feeding through a nasogastric tube. As with nasogastric tubes, gastrostomy tubes do not offer protection from colonized oral secretions.¹² Many researchers have found similar aspiration rates with gastrostomy and nasogastric tube feeding.^13,14

To reduce the rate of aspiration pneumonia in acute stroke patients, one might consider the use of early protective endotracheal intubation in high-risk patients—that is, those with severely decreased consciousness and severe facial palsy. There are two arguments in favor of such a strategy. First, according to our findings, pneumonia is a complication of the acute stage of the illness, occurring as early as the second day after stroke onset. Thus, one might reasonably expect that a short interval of endotracheal intubation and mechanical ventilation would be sufficient to get the patient past the most critical period. Second, if one refrains from endotracheal intubation initially, it will anyway become necessary later in a substantial number of patients: in their study, more than one third of patients with pneumonia required endotracheal intubation and mechanical ventilation.¹¹

This contrasts with the opinions of others who found that endotracheal intubation itself is not free of risk and may lead to injury to the teeth, the vocal cords, and the trachea. Additionally, the sedation and analgesia required for endotracheal intubation may cause a substantial fall in arterial blood pressure, thereby endangering the penumbral tissue in acute stroke patient. Finally, endotracheal intubation and sedation seriously interfere with early rehabilitation, which has been shown to be important for the outcome of acute stroke patients.¹⁵

 

Conclusion

We can conclude that feeding tubes offer only limited protection against aspiration pneumonia in patients with dysphagia caused by acute stroke. Patients with decreased level of consciousness and severe facial palsy are especially endangered by pneumonia in the first few days following stroke onset. Risks and benefits of more protective strategies such as early endotracheal intubation have to be established in future studies.

 

[Disclosure: Authors report no conflict of interest]

 

REFERENCES

 

1.        Mann G, Hankey GJ, Cameron D. Swallowing function after stroke: prognosis and prognostic factors at 6 months. Stroke. 1999; 30:744-8.

2.        Barer DH. The natural history and functional consequences of dysphagia after hemispheric stroke. J Neurol Neurosurg Psychiatry. 1989; 52:236-41.

3.        Smithard DG, O’Neill PA, Park C, Morris J. Complications and outcome after acute stroke - does dysphagia matter? Stroke. 1996; 27:1200-4.

4.        Teramoto S, Matsuse T, Fukuchi Y, Ouchi Y. Simple two-step swallowing provocation test for elderly patients with aspiration pneumonia. Lancet. 1999; 353:1243.

5.        Teramoto S, Fukuchi Y. Detection of aspiration and swallowing disorder in older stroke patients: simple swallowing provocation test versus water swallowing test. Arch Phys Med Rehabil. 2000; 81:1517-9.

6.        DePippo K, Holas MA, Reding MJ. Validation of the 3-oz water swallow test for aspiration following acute stroke. Arch Neurol. 1992; 49:1259-61.

7.        Gordon C, Hewer RL, Wade DT. Dysphagia in acute stroke. Br Med J (Clin Res Ed). 1987; 295:411-4.

8.        Hilker R, Poetter C, Findeisen N, Sobesky J, Jacobs A, Neveling M, et al. Nosocomial pneumonia after acute stroke—implications for neurological intensive care medicine. Stroke. 2003; 34:975-81.

9.        Joshi N, Localio R, Hamory B. A predictive risk index for nosocomial pneumonia in the intensive care unit. Am J Med. 1992; 93:135-42.

10.     Moulton C, Pennycook AG. Relation between Glasgow coma score and cough reflex. Lancet. 1994; 343:1261-2.

11.     Dziewas R, Ritter M, Schilling M, Konrad C, Oelenberg S, Nabavi DG, et al. Pneumonia in acute stroke patients fed by nasogastric tube. J Neurol Neurosurg Psychiatry. 2004; 75:852-6.

12.     Marik PE. Aspiration pneumonitis and aspiration pneumonia. N Engl J Med. 2001; 344:665-71.

13.     Baeten C, Hoefnagels J. Feeding via nasogastric tube or percutaneous endoscopic gastrostomy. A comparison. Scand J Gastroenterol Suppl. 1992; 194:95-8.

14.     Park RH, Allison MC, Lang J, Spence E, Morris AJ, Danesh BJ, et al. Randomised comparison of percutaneous endoscopic gastrostomy and nasogastric tube feeding in patients with persisting neurological dysphagia. BMJ. 1992; 304:1406-9.

15.     Indredavik B, Bakke F, Slordahl SA, Rokseth R, Hâheim LL. Treatment in a combined acute and rehabilitation stroke unit: which aspects are most important? Stroke. 1999; 30:917-23.