Refractory Central Neurogenic Hyperventilation: A Novel Approach Utilizing Mechanical Dead Space

Disordered breathing in severe cerebral illness - towards a conceptual framework

Despite potentially life-threatening symptoms of disordered breathing in severe cerebral illness, there are no clear recommendations on diagnostic and therapeutic strategies for these patients. To identify types of breathing disorders observed in severely neurological comprised patients, to direct further research on classification, pathophysiology, diagnosis and treatment for disordered breathing in cerebral disease. Data including polygraphy, transcutaneous capnometry, blood gas analysis and radiological examinations of patients with severe cerebral illness and disordered breathing admitted to the neurological intensive care were analyzed. Patients (15) presented with acquired central hypoventilation syndrome (ACHS), central bradypnea, central tachypnea, obstructive, mixed and central apneas and hypopneas, Cheyne Stokes respiration, ataxic (Biot's) breathing, cluster breathing and respiration alternans. Severe cerebral illness may result in an ACHS and in a variety of disorders of the respiratory rhythm. Two of these, abrupt switches between breathing patterns and respiration alternans, suggest the existence of a rhythmogenic respiratory network. Polygraphy, transcutaneous capnometry, blood gas analysis and MRI are promising tools for diagnosis and research alike.

Central neurogenic hyperventilation secondary to suspected metastatic renal cell carcinoma

Central neurogenic hyperventilation (CNH) is a neurogenic disorder rarely described within Emergency Medicine literature. CNH is a primary cause of hyperventilation, most commonly due to primary central nervous system neoplasms. Patient presentation varies based on the underlying cause, and may present with a sole chief complaint of dyspnea. We present a case of an adult male with a history of deep vein thrombosis, anticoagulated on apixaban, and extensively metastatic renal cell carcinoma who presented with a two-week history of dyspnea. Evaluation in the emergency department showed a primary respiratory alkalosis with a compensatory metabolic acidosis. Diagnostic work-up failed to reveal a cardiac, pulmonary, metabolic, or toxic cause. During the emergency department course, the patient became dysarthric and altered, at which point, computed tomography scan of the head revealed a pontine hemorrhage. The hemorrhage was stabilized with prothrombin complex concentrate, but the patient's dyspnea and mental status deteriorated throughout the course of his hospitalization. While the cause of the patient's hemorrhage was not elucidated, given the patient's widely metastatic disease, it was presumed to be secondary to metastasis. Our case highlights both a unique cause of a rare disorder of hyperventilation, and a diagnostic challenge to the emergency medicine provider. It is important to consider central causes of hyperventilation in patients with dyspnea and neurologic symptoms.

Central neurogenic hyperventilation in conscious patients due to CNS neoplasm: a case report and review of the literature on treatment

Background

Central neurogenic hyperventilation (CNH) is increasingly reported in conscious patients with a CNS neoplasm. We aimed to synthesize the available data on the treatment of this condition to guide clinicians in their approach.

Methods

We describe the case of a 39-year-old conscious woman with CNH secondary to glioma brainstem infiltration for whom hyperventilation was aborted with hydromorphone, dexamethasone, and brainstem radiotherapy. We then performed a review of the literature on the treatment of CNH in conscious patients due to a CNS neoplasm.

Results

A total of 31 studies reporting 33 cases fulfilled the selection criteria. The underlying neoplasm was lymphoma in 15 (45%) and glioma in 13 (39%) patients. Overall, CNH was aborted in 70% of cases. Opioids and sedatives overall seemed useful for symptom relief, but the benefit was often of short duration when the medication was administered orally or subcutaneously. Methadone and fentanyl were successful but rarely used. Chemotherapy was most effective in patients with lymphoma (89%), but not glioma (0%) or other neoplasms (0%). Patients with lymphoma (80%) and other tumors (100%) responded to radiotherapy more frequently than patients with glioma (43%). Corticosteroids were moderately effective. Subtotal surgical resection was successful in the 3 cases for which it was attempted.

Conclusion

Definitive treatment of the underlying neoplasm may be more successful in aborting hyperventilation. Variable rates of palliation have been observed with opioids and sedatives. Treatment of CNH is challenging but successful in a majority of cases.