Thread by @DrJaredDyer

1/ Have you ever been confused about the pulmonary management of neuromuscular disorders? If so, I promise you aren’t the only one! Check out this #tweetorial primer on the basics of NMD management. @VCU_PCCM @crit_caring_MD @AvrahamCooperMD @PulmPEEPs #CHESTTrainees #MedEd

2/ Neuromuscular diseases affect the respiratory system in 3 main areas:
1⃣Ventilatory Function
2⃣Cough Function
3⃣Swallowing and Airway Protection

As muscle weakness progresses, this will lead to alveolar hypoventilation with subsequent hypoxemia and hypercapnia.

3/ Objective means to assess respiratory muscle function include:
1⃣Maximal Inspiratory Pressure
2⃣Maximal Expiratory Pressure
3⃣Forced Vital Capacity (Supine)
4⃣Peak Cough Flow

MIP <60 mmHg and nocturnal oximetry are effective in detecting early respiratory insufficiency.

4/ The Canadian Alternatives in Noninvasive Ventilation (CANvent) group developed this staging system for progressive respiratory muscle weakness to help guide clinicians in the management of NMD patients.

5/ Patients will require assisted airway clearance once their peak cough expiratory flow drops below 270 L/min (normal 360-400 L/min). Airway clearance needs to be focused on both the proximal and peripheral airways.

6/ Proximal airway clearance, i.e. cough augmentation, can be achieved through both manual and mechanical means. We will start with the manual methods, which include the following:

1⃣ Manual Breath Stacking
2⃣Resuscitation Bag
3⃣Glossopharyngeal Breathing

7/Glossopharyngeal breathing is a form of positive pressure breathing (i.e. frog breathing) where patients take 25 consecutive small gulps of air (~50mL). This can add up to 1L to the FVC! @atscommunity
atsjournals.org/doi/full/10.11…

8/ Other manual methods for proximal airway clearance include manual cough assist maneuvers:
1⃣Abdominal Thrust
2⃣Chest Wall Thrust

9/ The mechanical insufflator-exsufflator device is the most commonly utilized cough augmentation technique. The insufflator acts as a lung recruitment maneuver while the exsufflator applies negative pressure during exhalation to increase expiratory flow.

10/ Peripheral airway clearance, i.e sputum mobilization, is achieved through the use of high frequency chest wall oscillation. Evidence for vest therapy is conflicting but it should be done in conjunction with cough augmentation.

11/ Worsening respiratory muscle weakness and symptoms of hypoventilation during sleep (daytime somnolence, morning headaches) should prompt a discussion about the use of NIV. Early use of NIV when the FVC <50% and PCO2 > 45mmHg has been shown to improve survival.

12/ This awesome chart by @nickmmark highlights the different forms of non-invasive pressure ventilation. AVAPS (average volume pressure support) is a great starting point for patients with NMD.

13/ AVAPS ensures that patients are receiving a desired tidal volume through dynamic adjustments to the inspiratory pressure (IPAP). This allows for continued delivery of adequate ventilation in the setting of progressive respiratory failure.

14/ Other key points with regards to NIV in neuromuscular disease patients:
1⃣Supplemental oxygen should not be prescribed without ventilatory support as it may mask atelectasis
2⃣Patients need longer inspiratory times to prevent early off-cycling from muscle weakness

That's all folks! Hope you learned something! @lkbrath @DanckersMD @amiksodhi @aggie07girl @DrMeganConroy @subanichandra @VCU_IMRes @Huzaifahsmd