Respiratory Care in Neuromuscular Respiratory Care in Neuromuscular DiseaseDisease

Cori Daines, MDCori Daines, MDPediatric Pulmonary MedicinePediatric Pulmonary Medicine

University of ArizonaUniversity of Arizona

Neuromuscular Disease

• Duchenne’s muscular dystrophy

• Becker’s muscular dystrophy

• Limb-Girdle muscular dystrophy

• Spinal muscular atrophy

• Myotonic dystrophy

Neuromuscular Disease

• Genetically inherited

• Muscle weakness– Extremities– Trunk/spine– Respiratory– Swallowing– Cardiac

Neuromuscular diseaseNeuromuscular disease

• Controller failureController failure

• Chest wall compromiseChest wall compromise

• Muscle weaknessMuscle weakness– HypotoniaHypotonia– HypertoniaHypertonia

Respiratory ControlRespiratory Control

• Maintain homeostasisMaintain homeostasis– OxygenOxygen– Carbon dioxideCarbon dioxide– Hydrogen ion concentration (pH)Hydrogen ion concentration (pH)

• Optimize mechanical efficiencyOptimize mechanical efficiency• Complex functionsComplex functions

– VocalizationVocalization– CoughCough– ExerciseExercise– Adaptation to diseaseAdaptation to disease

Respiratory MusclesRespiratory Muscles

• DiaphragmDiaphragm• IntercostalsIntercostals• Accessory muscles (shoulder girdle)Accessory muscles (shoulder girdle)• PharynxPharynx• LarynxLarynx• Abdominal wallAbdominal wall• PerineumPerineum

Physiologic impactPhysiologic impact

• Ventilatory impairmentVentilatory impairment• Oxygenation impairment [(A-a)DO2 Oxygenation impairment [(A-a)DO2 ]]• Sleep disordered breathingSleep disordered breathing• Maintenance of lung volumeMaintenance of lung volume• Growth of the lung in childrenGrowth of the lung in children• Lung clearance impairmentLung clearance impairment• Lung inflammation from aspirationLung inflammation from aspiration• Nocturnal vs diurnal dysfunction variesNocturnal vs diurnal dysfunction varies

PreventionPrevention

• Assuming that there is no primary lung Assuming that there is no primary lung disease most NMD patients can have normal disease most NMD patients can have normal lungslungs

• ““An ounce of prevention is worth a pound of An ounce of prevention is worth a pound of cure”cure”

• 4 E’s = “Expansion, Evacuation, Evasion and 4 E’s = “Expansion, Evacuation, Evasion and Evaluation”Evaluation”– i.e. expand the lungs, clear the airways, and avoid i.e. expand the lungs, clear the airways, and avoid

aspiration and infection aspiration and infection – Evaluate how the patient progresses acutely and Evaluate how the patient progresses acutely and

over the long termover the long term

Minimize work of breathingMinimize work of breathing• Normally 15% of energy = WOBNormally 15% of energy = WOB

• In NMD this can be exceededIn NMD this can be exceeded– Decreased use of energy in movementDecreased use of energy in movement– Increased work of breathing due to Increased work of breathing due to

inefficient system and/or stiff/obstructed inefficient system and/or stiff/obstructed lungslungs

• Increased WOB will lead to chronic Increased WOB will lead to chronic hypercapnea and compensatory hypercapnea and compensatory alkalosisalkalosis

ExpansionExpansion

• Weakness leads toWeakness leads to– Poor inspirationPoor inspiration– Atelectasis and decreased compliance due to fluid Atelectasis and decreased compliance due to fluid

accumulation and microatelectasisaccumulation and microatelectasis– Chest wall/Shoulder girdle contractureChest wall/Shoulder girdle contracture– Kyphoscoliosis (except DMD)Kyphoscoliosis (except DMD)

• Loss of MIP correlates with loss of lung Loss of MIP correlates with loss of lung volume and MIP < 30 are predictive of volume and MIP < 30 are predictive of increases in CO2increases in CO2

Duchenne MD: FVC vs AgeDuchenne MD: FVC vs Age

Bach et al. Arch Phys Med Rehabil 1981; 62:328Bach et al. Arch Phys Med Rehabil 1981; 62:328

ExpansionExpansion

• Reduced: TLC, VC, FRC, ERVReduced: TLC, VC, FRC, ERV• Balance between chest wall and Balance between chest wall and

diaphragmdiaphragm– Affects optimal position (Upright better with Affects optimal position (Upright better with

weak diaphragm)weak diaphragm)– Rate of loss of function affects degree of Rate of loss of function affects degree of

breathing intolerance: Rapid is worsebreathing intolerance: Rapid is worse

EvacuationEvacuation

• Optimal humidity and warmth to maintain ciliary Optimal humidity and warmth to maintain ciliary functionfunction

• CoughCough– SenseSense– Close glottisClose glottis– Pressurize pulmonary gas by tensing abdomen and Pressurize pulmonary gas by tensing abdomen and

perineum (200 cm H2O)perineum (200 cm H2O)– Explosively open airwayExplosively open airway– Continue cough to lower lung volumeContinue cough to lower lung volume

• Cough peak flow transients are 6 to 12 liters per Cough peak flow transients are 6 to 12 liters per second; i.e. 360 to 720 L/minsecond; i.e. 360 to 720 L/min

Pulmonary clearance failurePulmonary clearance failure

• Disrupted cilia due to drying and inflammationDisrupted cilia due to drying and inflammation• Low tidal volume (< 20 ml/kg)Low tidal volume (< 20 ml/kg)• Poor glottic closurePoor glottic closure• Poor abdominal compression Poor abdominal compression

– CPF < 2.7 L/sec = 160L/min predict failure of CPF < 2.7 L/sec = 160L/min predict failure of extubation in adults (i.e. < 2 L/min/kg)extubation in adults (i.e. < 2 L/min/kg)

• Poor coordinationPoor coordination• Inablility to continue to low lung volumeInablility to continue to low lung volume

EvacuationEvacuation

• Chest physiotherapyChest physiotherapy

• Stacking with voluntary coughStacking with voluntary cough

• Stacking with augmented coughStacking with augmented cough

• Mechanical insufflation-exsufflationMechanical insufflation-exsufflationTracheostomyTracheostomy

EVASION: Avoid pulmonary damageEVASION: Avoid pulmonary damage

• Growth failureGrowth failure– Poor expansionPoor expansion– Poor nutritionPoor nutrition

• AspirationAspiration

• Foreign body (tracheostomy)Foreign body (tracheostomy)

• Poor clearance with inflammatory Poor clearance with inflammatory processesprocesses

Evasion: AspirationEvasion: Aspiration• A tension exists between natural, pleasure giving aspects A tension exists between natural, pleasure giving aspects

of feeding and danger of aspiration and inadequate of feeding and danger of aspiration and inadequate nutritionnutrition

• Often this leads to an illogical approach; i.e. pt has to fail Often this leads to an illogical approach; i.e. pt has to fail oral feeds to go to alternative as opposed to succeed with oral feeds to go to alternative as opposed to succeed with oral feedings to move off of supportive modalities (NG,GT oral feedings to move off of supportive modalities (NG,GT etc)etc)

• Progresses early in SMA/Brainstem dysfunction and later Progresses early in SMA/Brainstem dysfunction and later in DMDin DMD

• Oral hygiene important even if NPOOral hygiene important even if NPO

EvaluationEvaluation

• History and physical including QOL and sleep History and physical including QOL and sleep questionnairequestionnaire

• Chest filmChest film• Lung volumesLung volumes• MIP/MEPMIP/MEP• Sniff MIPSniff MIP• Inspiratory flow reserveInspiratory flow reserve• Maximum insufflation capacityMaximum insufflation capacity• Cough peak flowsCough peak flows

Patient status changes with Patient status changes with viral respiratory infectionsviral respiratory infections

• Increased secretionsIncreased secretions• Decreased muscle strengthDecreased muscle strength• Surfactant dysfunction in LRISurfactant dysfunction in LRI• Transient increase in need for supportTransient increase in need for support• We commonly evaluate patients when We commonly evaluate patients when

they have recovered from an illness or they have recovered from an illness or are stableare stable

Dr. Bach: Outpatient ProtocolDr. Bach: Outpatient Protocol

• Patients at risk Patients at risk – During chest colds w/ assisted PCF below 270 LPM During chest colds w/ assisted PCF below 270 LPM

• Patients prescribed Patients prescribed – Oximeter and MIE deviceOximeter and MIE device

• Patients trained in Patients trained in – Air stacking insufflated volumes via mouth and nasal Air stacking insufflated volumes via mouth and nasal

interfaces interfaces – Manually assisted coughing Manually assisted coughing – Mechanical in-exsufflation at [+35 to +50] to [-35 to -50] cm Mechanical in-exsufflation at [+35 to +50] to [-35 to -50] cm

H2O H2O

Outpatient ProtocolOutpatient Protocol

• Patients given 1-hour access to Patients given 1-hour access to – Portable volume ventilator Portable volume ventilator – Cough Assist MIE (J. H. Emerson Co., Cambridge, MA) Cough Assist MIE (J. H. Emerson Co., Cambridge, MA) – Various mouthpieces and nasal interfaces Various mouthpieces and nasal interfaces

• Patients and care providers are instructed Patients and care providers are instructed – SaO2 <95% indicates hypoventilation or airway mucus SaO2 <95% indicates hypoventilation or airway mucus

accumulation that must be cleared to prevent atelectasis accumulation that must be cleared to prevent atelectasis and pneumonia and pneumonia

– Use SaO2 monitoring whenever fatigued, short of breath, or Use SaO2 monitoring whenever fatigued, short of breath, or ill ill

– Use noninvasive IPPV and manually and mechanically Use noninvasive IPPV and manually and mechanically assisted coughing as needed to maintain normal SaO2 at all assisted coughing as needed to maintain normal SaO2 at all times times

Outpatient ProtocolOutpatient Protocol

• Patients with elevated EtCO2 or daytime SaO2 <95% Patients with elevated EtCO2 or daytime SaO2 <95% – Undergo nocturnal SaO2 monitoring Undergo nocturnal SaO2 monitoring

• When symptomatic or nocturnal SaO2 mean <94% When symptomatic or nocturnal SaO2 mean <94% – A trial of nocturnal nasal IPPV is provided A trial of nocturnal nasal IPPV is provided

• People continue to use nocturnal nasal IPPV when People continue to use nocturnal nasal IPPV when they felt less fatigue and nocturnal mean SaO2 they felt less fatigue and nocturnal mean SaO2 increases. increases.

• Most young patients use noninvasive IPPV for the Most young patients use noninvasive IPPV for the first time to assist lung ventilation during chest first time to assist lung ventilation during chest infections. infections.

Respiratory muscle aids: IndicationsRespiratory muscle aids: Indications

• Failure to maintain a healthy lung with Failure to maintain a healthy lung with growth and optimal ventilatory functiongrowth and optimal ventilatory function– i.e. failing the 3 E’si.e. failing the 3 E’s

• Prevention is keyPrevention is key

• Optimize support in relation to the Optimize support in relation to the needs of the patientneeds of the patient

Using what the patient hasUsing what the patient has

• Daytime spontaneous respiration with Daytime spontaneous respiration with nocturnal support for control, airway nocturnal support for control, airway obstruction, recruitment of lung volumeobstruction, recruitment of lung volume

• Glossopharyngeal breathing during the Glossopharyngeal breathing during the daytime with nocturnal ventilationdaytime with nocturnal ventilation

• Optimizing cough and lung volume with Optimizing cough and lung volume with stacking maneuversstacking maneuvers

Glossopharyngeal breathingGlossopharyngeal breathing

Maximal insufflation capacityMaximal insufflation capacity

• Breath stackingBreath stacking• Measured unassisted with spontaneous Measured unassisted with spontaneous

breathes or GPB breathsbreathes or GPB breaths• Commonly 1.5x the VCCommonly 1.5x the VC• Can be augmented with interface and manual Can be augmented with interface and manual

resuscitator bagresuscitator bag• Maintain lung volume and compliance and Maintain lung volume and compliance and

chest wall compliancechest wall compliance

Inspiratory muscle aidsInspiratory muscle aids

• Rocking bed and abdominal beltRocking bed and abdominal belt– Disadvantage is no expansion of lung; i.e. Disadvantage is no expansion of lung; i.e.

frc to less than frcfrc to less than frc

• Negative pressure ventilatorsNegative pressure ventilators– Disadvantages are OSAS and aspirationDisadvantages are OSAS and aspiration

• Non-invasive IPPVNon-invasive IPPV

• Tracheostomy and IPPVTracheostomy and IPPV

Nocturnal supportNocturnal support

• Used prior to need for 24/7 supportUsed prior to need for 24/7 support

• Improves daytime PaO2, PaCO2Improves daytime PaO2, PaCO2

• Reduces respiratory muscle work at Reduces respiratory muscle work at night and rests the musclesnight and rests the muscles

• Reverses cor pulmonale perhaps in Reverses cor pulmonale perhaps in addition to O2 by improving lung volumeaddition to O2 by improving lung volume

Nocturnal supportNocturnal support

• Increases MIP and lung volumeIncreases MIP and lung volume• Improves compliance and FRC during the Improves compliance and FRC during the

daytimedaytime• Can be used even in patients with severe Can be used even in patients with severe

breathing intolerancebreathing intolerance– CCHS or Quadraparesis with daytime CCHS or Quadraparesis with daytime

diaphragmatic pacingdiaphragmatic pacing– GPB during daytimeGPB during daytime

• Can be transitioned to 24/7 with illnessesCan be transitioned to 24/7 with illnesses

NIPPV: InterfacesNIPPV: Interfaces

• Full face maskFull face mask

• Nasal maskNasal mask

• Custom maskCustom mask

• Mouthpiece / LipsealMouthpiece / Lipseal– Leakage and dental issuesLeakage and dental issues

• Sipper mouthpieceSipper mouthpiece

NIPPV: Nasal mask / ProngsNIPPV: Nasal mask / Prongs

• 2-3 x preferred compared 2-3 x preferred compared to mouthpieceto mouthpiece

• Problems:Problems:– Leak, esp mouthLeak, esp mouth– Nasal bridge pressure with Nasal bridge pressure with

maskmask– Gum erosion or compression Gum erosion or compression

with maskwith mask– Nasal erosion with prongsNasal erosion with prongs

• Chin strap may be neededChin strap may be needed

NIPPV: Full face maskNIPPV: Full face mask

• Decreased leakDecreased leak• DecreasedDecreased

– CoughCough– TalkingTalking– EatingEating

• Nocturnal use with Nocturnal use with daytime nasal maskdaytime nasal mask

NIPPV: Sipper / MouthpieceNIPPV: Sipper / Mouthpiece• Daytime useDaytime use

• Allows facial freedomAllows facial freedom

• Flexed mouthpiece +/- custom Flexed mouthpiece +/- custom orthodonticsorthodontics

• Intermittently used to augment Intermittently used to augment breathingbreathing

• Continuously usedContinuously used

NIPPV: Sipper / MouthpieceNIPPV: Sipper / Mouthpiece• Large VT set on ventilator or High insp Large VT set on ventilator or High insp

flow if pressure controlledflow if pressure controlled

• Allows stacking maneuversAllows stacking maneuvers

• Head/neck control for intermittent useHead/neck control for intermittent use

• Use of flexed mouthpiece with a back Use of flexed mouthpiece with a back pressure of 2-3 cmH2O can reduce low pressure of 2-3 cmH2O can reduce low pressure/disconnect alarmspressure/disconnect alarms

Complications of NIPPVComplications of NIPPV

• Facial and orthodontic changesFacial and orthodontic changes

• Aerophagia (PIP > 25 cmH2O)Aerophagia (PIP > 25 cmH2O)

• Nasal drying/congestion = humidifyNasal drying/congestion = humidify

• Volutrauma - air leakVolutrauma - air leak

TracheostomyTracheostomy

• ControversialControversial• Current view in rehab circles is that with Current view in rehab circles is that with

proper care a tracheostomy is never neededproper care a tracheostomy is never needed• Our experience is that tracheostomy may Our experience is that tracheostomy may

have a rolehave a role– Patient preferencePatient preference– Upper airway dysfunctionUpper airway dysfunction– Severe central airway obstruction by secretionsSevere central airway obstruction by secretions

VentilatorsVentilators

VentilatorsVentilators• Pressure cycled Pressure cycled vsvs Volume cycled Volume cycled

• Pressure cycled are often triggered by flow Pressure cycled are often triggered by flow sensing reducing work of breathingsensing reducing work of breathing

• Flow sensing is also important in pts with Flow sensing is also important in pts with high respiratory rates = infants/toddlershigh respiratory rates = infants/toddlers

VentilatorsVentilators• Leak can vary with sleep, position, and Leak can vary with sleep, position, and

effort which is problematic with volume effort which is problematic with volume cycled ventilatorscycled ventilators

• Variable airway resistance and/or Variable airway resistance and/or pulmonary or chest wall compliance better pulmonary or chest wall compliance better with volume settingswith volume settings

• Pressure cycling limits ability to stackPressure cycling limits ability to stack

Ventilator triggering and rateVentilator triggering and rate

• Small/weak or brainstem/CNS pts may Small/weak or brainstem/CNS pts may not trigger wellnot trigger well

• Spontaneous-timed modes are useful Spontaneous-timed modes are useful with a backup rate higher than with a backup rate higher than spontaneous when initiating ventilation spontaneous when initiating ventilation in infants/young childrenin infants/young children

• Back-up rates lower than spontaneous Back-up rates lower than spontaneous once comfortableonce comfortable

Ventilation goalsVentilation goals• Healthy lungs with good volumes and no atelectasisHealthy lungs with good volumes and no atelectasis• Rate on the low side and Vt or PIP on the high sideRate on the low side and Vt or PIP on the high side• PaCOPaCO22 = 35 = 35 ± ± 5 mmHg5 mmHg• Room airRoom air• Patient comfortPatient comfort

– Ability to trigger ventAbility to trigger vent– Ability to deliver needed volume/flow in timeAbility to deliver needed volume/flow in time– No auto-PEEPNo auto-PEEP– No auto-cycling / Ventilator-Patient dysynchronyNo auto-cycling / Ventilator-Patient dysynchrony

• Primary lung disease may change this approachPrimary lung disease may change this approach

BiPAP settingsBiPAP settings• S/T mode / High span IPAP/EPAPS/T mode / High span IPAP/EPAP

– If OSAS is main issue low span is appropriateIf OSAS is main issue low span is appropriate• IPAP range 15-18IPAP range 15-18

– May need higher with high UA resistance, non-May need higher with high UA resistance, non-compliant lungs, obesity/non-compliant chest wallcompliant lungs, obesity/non-compliant chest wall

– May need to be lower with high spont ratesMay need to be lower with high spont rates• EPAP range 2-4EPAP range 2-4

– Depending upon circuit may need 4 cmH2O to Depending upon circuit may need 4 cmH2O to avoid rebreathingavoid rebreathing

– High EPAP is rarely neededHigh EPAP is rarely needed

Other issuesOther issues

• Inspiratory timeInspiratory time– I:E of 1:2I:E of 1:2– Ti of 0.5 min (infant) and 1.0 (>infant)Ti of 0.5 min (infant) and 1.0 (>infant)

• Insp flow rate necessary to achieve pressure Insp flow rate necessary to achieve pressure comfortablycomfortably

• Trigger sensitivity set to reduce WOB, but not Trigger sensitivity set to reduce WOB, but not autocycleautocycle

• Pressure support may improve comfort with Pressure support may improve comfort with spontaneous breathsspontaneous breaths– Ultimately creates an S/T mode depending upon settingsUltimately creates an S/T mode depending upon settings

LTV system - PulmoneticsLTV system - Pulmonetics

LTV system - PulmoneticsLTV system - Pulmonetics

LTV systemLTV system

LTV: FeaturesLTV: Features

Control mode ventilationControl mode ventilation

Limited respiratory control / Inability to trigger breathsLimited respiratory control / Inability to trigger breaths

Assist Control ModeAssist Control Mode

Can trigger breaths, but needs support with each breathCan trigger breaths, but needs support with each breath

SIMV ModeSIMV Mode

Most patients, improved comfort, stable CO2sMost patients, improved comfort, stable CO2s

Bilevel ModeBilevel Mode

Mimic BiPAP / No Backup RateMimic BiPAP / No Backup Rate

Rise TimeRise Time

• Pressure Pressure controlcontrol

• Pressure Pressure supportsupport

• Flow in Flow in volume volume control is set control is set by Ti and Vtby Ti and Vt

Rise TimeRise Time

• Slow rise timeSlow rise time– Small ETSmall ET– Bronchospasm / AODBronchospasm / AOD– Pressure overshoot on PIPPressure overshoot on PIP

• Fast rise timeFast rise time– Short Ti / High respiratory rateShort Ti / High respiratory rate

• Vary with age; i.e. larger VT = faster rise timeVary with age; i.e. larger VT = faster rise time

Home ventilation realityHome ventilation reality

• Every patient is uniqueEvery patient is unique• These are “more guidelines rather than These are “more guidelines rather than

rules”rules”• Vary settings, interfaces, strategies to Vary settings, interfaces, strategies to

achieve goals of good health and achieve goals of good health and optimized quality of lifeoptimized quality of life

Discharge home: Medical IssuesDischarge home: Medical Issues

• Presence of a stable airwayPresence of a stable airway• FiO2 less than 40%FiO2 less than 40%• PCO2 safely maintainedPCO2 safely maintained• Nutritional intake optimalNutritional intake optimal• Other medical conditions well controlledOther medical conditions well controlled• Above may vary if palliative careAbove may vary if palliative care

Jardine E, Wallis C. Thorax 1998; 53:762Jardine E, Wallis C. Thorax 1998; 53:762

Discharge Home: SupportDischarge Home: Support

• Goals and plans clarified with family and Goals and plans clarified with family and caregiverscaregivers

• Family and respite caregivers trained in the 4 Family and respite caregivers trained in the 4 E’s and all equipmentE’s and all equipment

• Nursing support arranged for nighttimeNursing support arranged for nighttime• Equipment lists developed and implemented Equipment lists developed and implemented

with re-supply and funding addressedwith re-supply and funding addressed• Funding and insurance issues addressedFunding and insurance issues addressed