Respiratory Muscle Function Tests and Diaphragm Ultrasound Predict Nocturnal Hypoventilation in Slowly Progressive Myopathies

Introduction: In slowly progressive myopathies, diaphragm weakness early manifests through sleep-related hypoventilation as reflected by nocturnal hypercapnia. This study investigated whether daytime tests of respiratory muscle function and diaphragm ultrasound predict hypercapnia during sleep.Methods: Twenty-seven patients with genetic myopathies (myotonic dystrophy type 1 and 2, late-onset Pompe disease, facioscapulohumeral dystrophy; 48 ± 11 years) underwent overnight transcutaneous capnometry, spirometry, measurement of mouth occlusion pressures, and diaphragm ultrasound.Results: Sixteen out of 27 patients showed nocturnal hypercapnia (peak ptcCO2 ≥ 50 mmHg for ≥ 30 min or increase in ptcCO2 by 10 mmHg or more from the baseline value). In these patients, forced vital capacity (FVC; % predicted) and maximum inspiratory pressure (MIP; % of lower limit or normal or LLN) were significantly reduced compared to normocapnic individuals. Nocturnal hypercapnia was predicted by reduction in FVC of <60% [sensitivity, 1.0; area under the curve (AUC), 0.82] and MIP (%LLN) <120% (sensitivity, 0.83; AUC, 0.84), the latter reflecting that in patients with neuromuscular disease, pretest likelihood of abnormality is per se higher than in healthy subjects. Diaphragm excursion velocity during a sniff maneuver excluded nocturnal hypercapnia with high sensitivity (0.90) using a cutoff of 8.0 cm/s.Conclusion: In slowly progressive myopathies, nocturnal hypercapnia is predicted by FVC <60% or MIP <120% (LLN). As a novelty, nocturnal hypercapnia can be excluded with acceptable sensitivity by diaphragm excursion velocity >8.0 cm/s on diaphragm ultrasound.

Intermittent abdominal pressure ventilation: feasibility and efficacy in neuromuscular disease. A case report

he standard treatment for patients with neuromuscular respiratory failure is non-invasive ventilation (NIV) as non-invasive ventilation support-setting (NVS). NVS is administered through a nasal or face mask and/or mouthpiece with the potential to cause nasal ulcers, discomfort, and/or aesthetic issues, resulting in poor compliance. We reported the observation of a 45-year-old woman with limb-girdle muscular dystrophy (LGMD), secondary to Dysferlin deficiency, who was on NVS since 2017 for nocturnal hypoventilation. In 2018, despite nocturnal ventilation, due to weight gain and daytime hypoventilation, a nasal mask was introduced. We initiated daytime intermittent abdominal pressure ventilation (IAPV) to mitigate cosmetic problems, improving in pO2 and decreasing in pCO2 versus baseline (52>84 mmHg, 46>33 mmHg respectively) at 6 (85 mmHg, 42 mmHg) and 18 months (93 mmHg, 38 mmHg), respectively. IAPV was effective, safe, and well-tolerated in our patients who did not tolerate standard daytime NVS with the known interface.

Diaphragm dysfunction (paralysis) in a cystic fibrosis patient

Diaphragmatic paralysis (DP) is a rare disease and usually occurs secondary to systemic processes, although idiopathic forms have been described. Management of diaphragmatic paralysis depends on multiple factors, including the etiology, presence, or absence of symptoms, and more importantly, the presence of nocturnal hypoventilation. DP has been described in both unilateral and bilateral forms. In unilateral DP, most patients are asymptomatic and often do not require intervention. Symptomatic patients with unilateral DP, however, will require plication. In bilateral DP, phrenic nerve pacing or nasal continuous positive airway pressure, bilateral positive airway pressure (CPAP BiPAP), or intermittent positive pressure ventilation by the nasal or oral mask is recommended. We describe a case of unilateral DP in a cystic fibrosis patient treated by surgical plication.

Diaphragm Dysfunction (Paralysis) in a Cystic Fibrosis Patient

Diaphragmatic Paralysis (DP) is a rare disease and usually occurs secondary to systemic processes, although idiopathic forms have been described. Management of diaphragmatic paralysis depends on multiple factors, including the etiology, presence, or absence of symptoms, and more importantly, the presence of nocturnal hypoventilation. DP has been described in both unilateral and bilateral forms. In unilateral DP, most patients are asymptomatic and often do not require intervention. Symptomatic patients with unilateral DP, however, will require plication. In bilateral DP, phrenic nerve pacing or nasal Continuous Positive Airway Pressure, Bilateral Positive Airway Pressure (CPAP BiPAP), or intermittent positive pressure ventilation by the nasal or oral mask is recommended. We describe a case of unilateral DP in a cystic fibrosis patient treated by surgical plication.

Assessment of Nocturnal Hypoventilation by Different Methods and Definitions in Children with Neuromuscular Disease: Oxycapnography and Blood Gas Analysis

Objective: To investigate whether partial arterial carbon dioxide pressure (PaCO2) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) is concordant with nocturnal end-tidal CO2 (PetCO2) measurement obtained by a noninvasive method of oxycapnography in children with neuromuscular disease (NMD). Methods: Twenty-one patients aged 6-18 years with a confirmed diagnosis of NMD were enrolled. Each patient underwent a nocturnal oxycapnography study using an orinasal probe and a pulse oximetry finger probe to record PetCO2, oxygen saturation (SpO2), pulse rate, and respiratory rate. Arterial blood gas analysis was performed to record PaCO2 levels on three occasions at night (23: 00 pm, 03: 00 am, 07: 00 am). Results: The mean overnight PaCO2 level of the three blood gas analyses (mean PaCO2noct) was 41.78±4.69 mmHg. A significant change was observed between mean PaCO2 23: 00 and PaCO2 07: 00 levels (p=0.032). There was no significant difference between PaCO2, PetCO2, and SpO2 levels in the NMD group. The interclass correlation coefficient between PaCO2 07: 00 and PetCO2 levels was 0.791 (95% CI: 0.533-0.923); the interclass correlation coefficient between overnight mean PaCO2 and PetCO2 levels was 0.811 (95% CI: 0.533-0.923). Conclusion: Our study indicates that nocturnal PetCO2 and PaCO2 levels were statistically comparable but the use of PaCO2 alone is not adequate to make an early diagnosis of NH in NMD. There is a need for making more restrictive definitions for NH, and conducting studies with larger study populations to reach an agreement on the best definition of hypoventilation, and updating consensus guidelines.