An 87-year-old Caucasian man was transferred from another hospital after an episode of altered mental status secondary to hypercapnea requiring intubation. His past medical history included type 2 diabetes, stage 3 chronic kidney disease, and heart failure with preserved ejection fraction. He was a lifelong non-cigarette smoker. Per the family he was complaining of shortness of breath, weight gain and worsening leg swelling for 3 weeks, and was progressively more somnolent over the last week. On admission to the outside hospital the results of his laboratory tests were significant for a normal blood glucose of 176mg/dL, normal white blood cell count at 7000 cells/mm3, creatinine of 1.6mg/dL (at his baseline), elevated brain natriuretic peptide at 778pg/mL and negative toxicology screen. He had no history of opioid or benzodiazepine usage. His ABG showed acute on chronic hypercapnea with a pH of 7.22, partial pressure of carbon dioxide (pCO2) of 83mmHg and bicarbonate (HCO3) of 36mmol/L requiring intubation explaining his altered mental status. He was noted to be in congestive cardiac failure and was given diuretics and eventually he was extubated. He was transferred to our institution on nightly bilevel positive airway pressure (bipap) for his unexplained hypercapnic failure. His only complaint on transfer was his chronic two-pillow orthopnea.\nOn arrival he was in no acute distress with a heart rate of 74, respiratory rate of 20, blood pressure of 107/65mmHg, and oxygen saturation of 98% on 2L nasal cannula. A cardiovascular and respiratory system examination was unrevealing with normal jugular venous pressure and normal cardiac examination. There was paradoxical abdominal motion with the abdominal wall moving inwards on inspiration. A neurologic examination revealed 3/5 strength in his left deltoid and decreased biceps reflexes bilaterally. Power, tone and reflexes were normal in both his lower limbs. He also had severe osteoarthrosis of distal and proximal interphalangeal joints bilaterally with Heberden’s nodes.\nHis ABG on room air showed a partial pressure of oxygen of 64mmHg, pCO2 of 53mmHg, HCO3 of 28mmol/L and a pH of 7.33 with a normal A-a gradient of 18. This was consistent with chronic respiratory acidosis secondary to hypoventilation, given the normal A-a gradient. A chest X-ray showed elevated hemidiaphragms bilaterally (Figure ). Pulmonary function testing showed a restrictive pattern with a normal ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of 0.79 (114% predicted), with FEV1 and FVC 49 and 42% of predicted respectively. There were also significantly decreased maximum inspiratory and maximum expiratory pressures of 27.2 and 31.4% predicted; and a decrease in FVC of 22% from the sitting to supine position suggestive of neuromuscular weakness (>20%). The diffusing capacity was normal suggesting a chest wall or neuromuscular cause of restrictive lung mechanics.\nGiven his abnormal neurologic examination with left deltoid weakness and decreased biceps reflexes, our differential included respiratory neuromuscular weakness from cervical spondylosis and phrenic nerve root compression (given the C5 neurological deficits); or possible cervical myelopathy at C5/C6. The absent biceps reflex (C5 and C6) raised suspicion for myelopathy at the C5 to C6 level although this is typically associated with a brisk triceps reflex (C7). The lack of neurological findings in his lower extremities also argued against myelopathy, but given the potential variable manifestations of cervical myelopathy, an electromyogram (EMG) and nerve conduction study (NCS) were performed. The EMG and NCS revealed decreased amplitude in the phrenic nerves bilaterally and radiculopathy in his upper limbs, suggestive of nerve root compression at the cervical foraminal level. There was no evidence of amyotrophic lateral sclerosis or myopathy on EMG/NCS and serum creatine phosphokinase was normal. A cervical MRI was performed and showed severe bilateral foraminal narrowing at C3, C4 and C5 with no evidence of myelopathy, confirming the diagnosis of phrenic nerve root compression from cervical spondylosis as the cause of hypoventilation. When he developed pulmonary edema, the resultant decreased lung compliance placed an increased respiratory load on his weakened neuromuscular apparatus leading to worsening hypercapnea and resultant metabolic encephalopathy with altered mental status. Carbon dioxide, being readily diffusible across the blood–brain barrier is a well-known cause of encephalopathy in the setting of hypercapnea.\nHe was offered surgical decompression of cervical motor roots or possible diaphragmatic pacing. Given his age, he opted for conservative management with nightly bipap to rest his respiratory muscles at night. He showed significant improvement with night-time bipap and felt less fatigued during the day, probably from the rest provided to his respiratory neuromuscular apparatus. Following discharge he remained stable but gradually became less compliant with bipap. He had four admissions in 2 years with hypercapnic respiratory failure in the setting of pulmonary edema from heart failure. Pulmonary edema and the resultant decreased lung compliance placed an increased respiratory load on his weakened neuromuscular apparatus. As expected he fatigued more easily with his weakened neuromusculature leading to hypoventilation and worsening hypercapnea. He required continuous bipap while hospitalized until diuresis improved chest wall compliance and respiratory mechanics. He continued to refuse invasive therapies and was managed conservatively with nightly bipap. He developed evidence of right ventricular failure and pulmonary hypertension on echo from a combination of pulmonary venous hypertension from heart failure and chronic hypoxia from hypoventilation secondary to his neuromuscular weakness. Given his recurrent episodes of respiratory failure and worsening heart failure he was eventually transitioned to hospice care.
A 64-year-old man was referred to the orthopaedic service with right hemidiaphragm paralysis. He had initially presented to his general practitioner reporting subjective shortness of breath after stand-up paddleboarding. His past medical history was significant for asbestos exposure and polio. Chest radiograph revealed an elevated right hemidiaphragm (Figures and ). A previous chest radiograph taken five years before showed normal diaphragmatic contours. He was subsequently referred to the respiratory physicians where workup included a chest CT scan (which revealed no intrathoracic abnormality) and dynamic fluoroscopic sniffing test (which confirmed complete right hemidiaphragm paralysis). He reported innocuous injuries to his neck in the past and intermittent neck pain for which he had previously consulted both a chiropractor and an osteopath. An MRI scan was undertaken which showed right-sided cervical foraminal stenosis (with uncovertebral and facet joint osteophytic changes at C3/4 and C4/5) (). He was therefore referred to the orthopaedic service. On examination, he had no focal cervical spine tenderness with a well-preserved range of motion. He did have some generalized right shoulder girdle and upper limb wasting and weakness compared to the left (presumed to be secondary to his postpolio syndrome). His upper limb reflexes were intact and symmetrical with the contralateral side.\nThe underlying cause for his hemidiaphragm paralysis, whether it was related to his cervical foraminal stenosis or postpolio syndrome, was indeterminant ().\nAfter obtaining multiple subspecialist opinions, a decision was made to proceed with posterior right C3/4 and C4/5 foraminotomies accepting that this may not have any effect on his shortness of breath. Surgery proceeded uneventfully as did postoperative recovery. By three months postoperatively, his hemidiaphragm paralysis had completely resolved on chest radiograph, and his shortness of breath had also improved (). Comparison of preoperative and postoperative spirometry lung function showed significant improvements in all parameters tested: increases in FVC from 3.88L to 4.86L, FEV1 from 2.44L to 3.13L, TLC from 5.11L to 7.65L, FRCpl from 2.61 to 3.63, and RV from 1.23L to 2.58L. A graphic representation of these findings is shown in . A satisfactory outcome was thus achieved.