Respiratory complications of neurological diseases

INTRODUCTION

Muscular weakness is a common representation of various neurological diseases, often leading to a wide aspect of complications. The most common life-threatening complications of neurological diseases are infections and respiratory failure. Cerebrovascular accident (CVA) is a major contributor to respiratory complications, including sleep apnea, aspiration pneumonia, and respiratory failure.^[1] Traumatic brain injury (TBI) can be caused by blunt trauma or penetrating injury. Manifestations of TBI include hematomas, concussion, and most commonly hemorrhagic CVA. Respiratory complications are similar to those resulting from a stroke.^[2] Status epilepticus causes aspiration during the seizure resulting in aspiration pneumonia. Moreover, breathing dysfunction may lead to sudden unexpected death in epilepsy.^[3] Viral encephalitis is often caused by herpes simplex, which often results in coma.^[4] Seizures and respiration muscle weakness during the coma cause aspiration pneumonia. Coma necessitates the need for mechanical ventilation, which in the long term, increases the chances of getting infected with hospital-acquired pneumonia.^[5] Guillain-Barre syndrome is a rare neurological disease that usually manifests after Campylobacter jejuni infection.^[6] Bulbar respiratory center failure induces respiratory failure that requires invasive intervention. In addition, weakness of pharyngeal and mastication muscles can cause aspiration leading to pneumonia.^[7] Alzheimer’s disease manifestations consist of cognitive impairment, muscle weakness, and reflex weakness. In advanced stages, pharyngeal reflex weakness induces aspiration pneumonia which can be fatal in some cases.^[8] Parkinson’s disease (PD) causes weakness in mastication muscles, appearing as difficulty in chewing food which progresses to aspiration pneumonia. In addition, dyspnea is a common respiratory symptom of PD induced by breathing dysfunction and anxiety.^[9] Myasthenia gravis (MG) manifests as muscle weakness, rapid fatigue, ptosis, diplopia, skeletal muscles and respiration muscles weakness, and cough reflex weakness. Consequently, weakness of the cough reflex and respiration muscles results in respiratory failure and/or pneumonia.^[10] This study observes the neurological disorders discussed above and their corresponding respiratory complications, their diagnostic tools, and their management. Provided that, this observation aims to decrease the morbidity and mortality rates and provide a better general state of patients with neurological diseases.

MATERIALS AND METHODS

RESULTS

This study included 100 patients with a neurological disease diagnosis and developed respiratory complications. Their ages ranged from 18 to 89 years. The gender distribution of patients was 50 males and 50 females. The number of patients who smoked was 38 (23 males and 15 females) and non-smokers were 62. Table 1 presents the neurological disease diagnosis that developed respiratory complications. The clinical diagnosis was made based on the clinical findings upon inspection, palpation, auscultation, and percussion. In addition, radiographic imaging and laboratory testing helped further in the diagnosis. The conducted tests are divided into four categories: Radiographic investigations, arterial blood gas (ABG), oxygen saturation (SpO₂) levels, and C-reactive protein (CRP) levels. Table 2 presents the type of respiratory complications associated with neurological diseases. Various radiographic investigations were carried out including chest-X-ray (CXR) and thoracic computed tomography (CT). Table 3 presents the numbers and the percentages of the CXR and thoracic CT findings.

It was found through CXR and CT imaging that most of the aspiration pneumonia cases were located in the right lung with a percentage of 83%, whereas 17% of the cases were located in the left lung. Regarding partial pressure of oxygen (PaO₂) in the arterial blood analysis, the results were as follows: The percentage of patients who had normal PaO₂ levels was 23%. On the contrary, the percentage of patients who had low PaO₂ levels was 77%. Regarding partial pressure of carbon dioxide (PaCO₂) in arterial blood analysis, the results were as follows: The percentage of patients who had normal PaCO₂ levels was 40%. However, the percentage of patients who had high PaCO₂ levels was 60%. Note that the normal ranges are PaO₂ (75–100) mmHg and PCO₃ (35–45) mmHg.^[11]

Regarding SpO₂ assessment, the results were as follows: The percentage of patients who had normal SpO₂ levels was 21%. However, the percentage of patients who had insufficient SpO₂ was 30%, whereas for those who had decreased SpO₂, the percentage was 20%. Subsequently, the rest of the percentages for critical status, severe hypoxia, and acute danger to life were 11%, 10%, and 8%, respectively. Reference values of SpO₂ were normal SpO_2: 98–100%, insufficient SpO_2: 95–97%, decreased SpO_2: 90–94%, critical <90%, severe hypoxia <80%, and acute danger to life <70%.^[12]

Regarding CRP levels, all values were high and ranged between 13.4 and 348 mg/dL. Note that the normal range for CRP should be <0.3 mg/dL.^[13]

The treatments that were administered were divided into three groups: Physical, pharmacological, and interventional therapies. Physical therapies that were conducted include chest physical therapy, secretions suctioning, postural drainage, and placement of nasal cannula or respiratory face mask. Pharmacological treatments used are antibiotics such as ceftriaxone: ROSS, levofloxacin: LEVO, vancomycin: VANCONEX, C bactam: C BACTAM, clindamycin: CLINDO PLUS, and metronidazole: FLAGYL; proton pump inhibitors such as omeprazole: RISEK; anticoagulants such as enoxaparin sodium: ENOXIR; antiplatelets such as aspirin: AVENZOR; loop diuretics such as furosemide: LASIX; rehydration fluids such as normal saline; analgesic and antipyretic drugs such as acetaminophen: CETAMOL; glucocorticoids such as prednisone: PREDLON; calcium channel blockers such as amlodipine: DIPIVASC; and HMG-CoA reductase inhibitors such as rosuvastatin: ROSOVA. Interventional therapies that have been used were intubation with mechanical ventilation or tracheostomy with mechanical ventilation. Chest physical therapy, ceftriaxone, levofloxacin, omeprazole, aspirin, furosemide, acetaminophen, rosuvastatin, valproate sodium and/or levetiracetam, normal saline, and respiratory face mask were administered for non-critical cases. Intubation with mechanical ventilation or tracheostomy with mechanical ventilation was conducted in critical cases. The treatment plan mentioned above was expected to treat the respiratory complications, relieve neurological symptoms, and stabilize and improve the patient’s overall condition. Respiratory complications recovered in 70% of the patients with a stable and improved general state. On the other hand, 20% of the patients did not improve and suffered instability. Unfortunately, 10% of patients died due to respiratory complications.

DISCUSSION

CVA had the highest percentage of occurrence of respiratory complications. CVA has a wide range of causes and multiple predispositions.^[1] Aspiration pneumonia had the highest occurrence rate among respiratory complications. Neurological diseases often lead to the failure of physiological defense mechanisms essential to maintaining respiratory airway integrity. Factors that contribute to develop aspiration pneumonia include respiration, pharyngeal, and mastication muscle weakness as well as immobility, since the patient is most often asleep or unconscious, which increases the chances of aspiration. Furthermore, tracheal intubation escalates the opportunity of acquiring aspiration pneumonia.

Pleural effusion, pneumothorax, and respiratory failure are less common since muscle weakness is the most common manifestation of all neurological diseases. However, muscle weakness does not have a role in these diseases’ development that is why they occur less in neurological diseases. Moreover, these diseases typically develop in the advanced stages of neurological diseases when the patient’s overall condition deteriorates.

Regarding imaging results, pulmonary densities and infiltrates were the most common findings as they are typical presentations in aspiration pneumonia. The rest of the radiographic findings were less common and were seen in critical, serious, and rare respiratory diseases.

The right lung had a higher incidence of pneumonia than the left lung due to the physiological anatomy of the right bronchus, which is higher and more vertical in position, shorter in length, and wider in diameter than the left bronchus. Subsequently, the right lung is more exposed to aspiration, leading to a higher rate of infections.

ABG results indicated that most patients had low levels of PaO₂ and high levels of PaCO₂. This illustrates that most patients had type 2 respiratory failure. In such a manner, this is a normal outcome of a neurological disease since type 2 is usually caused by extrapulmonary diseases.

SpO₂ levels were low in most patients because they suffered from different levels of pneumonia, pleural effusion, pneumothorax, and pulmonary failure. These diseases contribute to various mechanisms causing hypoxia. These mechanisms include hypoventilation, ventilation-perfusion mismatch, and right-to-left shunt.^[14]

The body’s reaction to any inflammation is by increasing CRP levels in the bloodstream. This clarifies the high CRP levels in this study.

Prevention protocols recommended by this study include suctioning secretions regularly and positioning the bed at a 30°–45° angle to prevent secretions build up and aspiration. In addition, the patient should undergo nothing by mouth protocol and receive a nasogastric tube insertion. Subsequently, intubation is required if the Glasgow Coma Scale equals 8 or less.^[15] Early antithrombotic prevention from pulmonary embolism is recommended, but it is a contraindication for hemorrhagic CVA patients. However, compression stockings and intermittent pneumatic compression devices can also help prevent pulmonary embolisms. Unfortunately, they are not available in our country.

Regarding early diagnosis, regular clinical assessments, including complete blood count, ABG, and CRP levels, are recommended. CXR should be done for patients with abnormal clinical assessments and laboratory testing to confirm the diagnosis and start the treatment. This study suggests that these patients should receive special care and should be placed in a specialized neurological intensive care unit.

The study faced limitations such as difficulties in obtaining patient information from hard copy files and obstacles in acknowledging the sequence of events that led the patient to this status. In addition, the inability to undergo required scans because of resource limitations and the unavailability of advanced imaging techniques and devices. Furthermore, there were difficulties locating the patients since they were not present in a specialized intensive care unit, rather they were displaced.

The Italian study titled “practical approach to respiratory emergencies in neurological diseases”^[16] shares numerous similarities and results with this study. Both studies concluded that pneumonia is the most common respiratory complication of neurological diseases. This emphasizes the reliability and inclusivity of investigations done in this study. It also shows the importance of early diagnosis of pneumonia in high-risk patients and immediate treatment.

Both studies concluded that CVA is the most common neurological disease associated with pneumonia. Taking into account the time difference between both studies, this demonstrates a lack of awareness toward early diagnosis and prevention of pneumonia in CVA patients over the years. This amplifies the importance of this study in raising awareness of these neglected life-threatening complications.

Mortality rates are notably high due to respiratory complications; this indicates that they cause death in neurological disease patients more than the disease itself. This study highlights the significance of regular investigations and prolonged prevention of these complications to decrease mortality rates in these patients.

CONCLUSION

This study proved that the most common cause of death in patients with neurological diseases is respiratory complications. It manifested that early diagnosis and treatment of these complications maintain the stability of the patient’s general state and reduce their mortality rates. In addition, it identified the most common and most efficient treatment plans that can be administered to control and treat these complications. Respiratory complications pose a significant threat to the health of patients with neurological diseases. Early diagnosis, prevention, and effective treatment are vital to improving patient outcomes. Preventive measures, specialized care units, and tailored treatments help mitigate mortality rates. Consequently, this study underscores the best examinations and analyses that must be conducted to diagnose these complications accurately. This ensures that patients will not be exposed to expensive and high-risk tests without proven benefits. In conclusion, this study aims to raise awareness about the necessity of periodic investigations for these complications to avoid their occurrence and deterioration of the patient’s health.