Mechanical Ventilation In Mechanical Ventilation In ARDS Versus COPDARDS Versus COPD

Prof. Dr Alaa Prof. Dr Alaa KoraaKoraaDr. Hanaa El GendyDr. Hanaa El Gendy

PFTPFT ObstructivObstructivee

RestrictiveRestrictive

-FEV1: normally >80% of -FEV1: normally >80% of FVC.FVC.

-FVC-FVC

-FEV1/ FVC ratio-FEV1/ FVC ratio

-VC-VC

-TLC-TLC

-RV-RV

-FRC-FRC

-MMEFR=FEFR 25-75% of -MMEFR=FEFR 25-75% of VCVC

-Total compliance-Total compliance

- Airway resistance- Airway resistance

- Work of breathing- Work of breathing

Little effectLittle effect

( < 75% predicted ) ( < 75% predicted )

Normal or Normal or

Air trappingAir trapping

NormalNormal

Normal or Normal or

No air trappingNo air trappingNormalNormal

NormalNormal

Spirograph In Different Respiratory DiseasesSpirograph In Different Respiratory Diseases

Normal Flow Volume LoopNormal Flow Volume Loop

Flow-Volume Loops In Different Respiratory DiseasesFlow-Volume Loops In Different Respiratory Diseases

Acute Respiratory Distress Syndrome Acute Respiratory Distress Syndrome (ARDS)(ARDS)

It is a clinical syndrome characterized by a pulmonary It is a clinical syndrome characterized by a pulmonary disorder resulting from diffuse injury to the alveolo-disorder resulting from diffuse injury to the alveolo-capillay membrane . capillay membrane .

Acute Lung Injury Acute Lung Injury (ALI)(ALI) has been used as a term for has been used as a term for hypoxemic respiratory failure, a severe version of which hypoxemic respiratory failure, a severe version of which is is (ARDS)(ARDS). .

Criteria of ARDS: Criteria of ARDS:

Acute onset.Acute onset.

Bilateral diffuse pulmonary infiltrates on chest x-ray. Bilateral diffuse pulmonary infiltrates on chest x-ray.

Bedside finding of tachypnea, dyspnea and crackles. Bedside finding of tachypnea, dyspnea and crackles.

Pulmonary Capillary Wedge Pressure <18mmHg or no Pulmonary Capillary Wedge Pressure <18mmHg or no evidence of LA hypertension.evidence of LA hypertension.

PaO2/FiO2 <300 = ALI.PaO2/FiO2 <300 = ALI.

PaO2/FiO2 <200 = ARDS. PaO2/FiO2 <200 = ARDS.

One or more underlying disease process known to be One or more underlying disease process known to be associated with ARDS.associated with ARDS.

What Cause ALI?What Cause ALI?

Direct injury Direct injury (primary, pulmonary)(primary, pulmonary)

Indirect Injury Indirect Injury

(secondary, extrapulmonary)(secondary, extrapulmonary)

Pathologic Changes In ARDSPathologic Changes In ARDS

Management Of ARDSManagement Of ARDS

The cornerstone of treatment is to keep the PaO2 The cornerstone of treatment is to keep the PaO2 >60mmHg, without causing injury to the lungs with >60mmHg, without causing injury to the lungs with excessive O2 or volutrauma.excessive O2 or volutrauma.

   Pressure control ventilation is more versatile than Pressure control ventilation is more versatile than

volume control, although breaths should be volume volume control, although breaths should be volume limited, to prevent stretch injury to the alveoli.limited, to prevent stretch injury to the alveoli.

We must have a holistic multisystem approach of the We must have a holistic multisystem approach of the ABCDEFGABCDEFG

Ventilation Strategy in ARDSVentilation Strategy in ARDS

* * Keep the PaO2 over 60mmHg or over 50mmHg at the Keep the PaO2 over 60mmHg or over 50mmHg at the very least.very least.

** Avoid volutrauma, barotraumas and biotrauma Avoid volutrauma, barotraumas and biotrauma (VIL)(VIL), , by keeping the tidal volumes in the 4-6ml/kg range and  by keeping the tidal volumes in the 4-6ml/kg range and  airway plateau pressure below 30 cmH2O .airway plateau pressure below 30 cmH2O .

** Peak airway pressure 20-40 cmH2O or < 20 cmH2O Peak airway pressure 20-40 cmH2O or < 20 cmH2O above PEEP.above PEEP.

** PEEP values of 2-3 cmH2O above lower PEEP values of 2-3 cmH2O above lower inflection point (LIP).inflection point (LIP).

** Lower respiratory rate. Lower respiratory rate.

** Inverse ratio ventilation.Inverse ratio ventilation.

** Permissive hypercapnia. Permissive hypercapnia.

** Low inspiratory flow.Low inspiratory flow.

The advantages of using PCV The advantages of using PCV in ALIin ALI

(1) Gas Distribution:(1) Gas Distribution:

(2) Control of mean airway pressure(2) Control of mean airway pressure

It is possible to increase the mean airway pressure, by It is possible to increase the mean airway pressure, by prolongation of the inspiratory time prolongation of the inspiratory time auto-PEEPauto-PEEP..

Inverse ratio ventilationInverse ratio ventilation, is a key part of the , is a key part of the open lung approachopen lung approach to ARDS and  is the basis of some to ARDS and  is the basis of some pressure controlled modes - pressure controlled modes - BiLEVELBiLEVEL/APRV/APRV..

Open Lung ApproachOpen Lung Approach

Phasic opening and closing of injured lung units causes Phasic opening and closing of injured lung units causes further injury to lung tissue . The low tidal volume further injury to lung tissue . The low tidal volume approach amount of phasic stretch of lung units approach amount of phasic stretch of lung units in inspiration, to prevent (VIL). in inspiration, to prevent (VIL).

Open lung approach, stenting the airways open at end Open lung approach, stenting the airways open at end expiration, using PEEP just above Pflex” (the lower expiration, using PEEP just above Pflex” (the lower inflection point on the pressure volume curve).inflection point on the pressure volume curve).

Static volume pressure curve of an injured lung: the lungs are said to be most Static volume pressure curve of an injured lung: the lungs are said to be most compliant between the lower inflection point of the curve and the upper compliant between the lower inflection point of the curve and the upper inflection point, beyond which overdistension takes place.inflection point, beyond which overdistension takes place.

PEEP Endpoints :PEEP Endpoints :

Best PaO2 Best PaO2 Best O2 delivery Best O2 delivery Lowest shunt Lowest shunt Best QtBest Qt Highest compliance Highest compliance lowest Vd / Vt lowest Vd / Vt Pplat < 30 cm H2OPplat < 30 cm H2O Best CT areationBest CT areation Until P/V curve become concave.Until P/V curve become concave.

What is a recruitment What is a recruitment maneuver?maneuver?

Recruitment maneuvers are used to reinflate collapsed Recruitment maneuvers are used to reinflate collapsed alveoli, a sustained pressure is applied, and PEEP is alveoli, a sustained pressure is applied, and PEEP is used to prevent derecruitment. used to prevent derecruitment.

Measurement of positive end-expiratory pressure (PEEP)-induced alveolar recruitment using the pressure–volume (PV) curve. The PV curves of the respiratory system recorded from zero end-expiratory pressure (ZEEP) and from PEEP are superimposed on a common volume axis. '0' volume corresponds to the end-expiratory lung volume (EELV) on ZEEP. The first point of the PEEP PV curve corresponds to the increase in EELV induced by PEEP (Δ EELV). On this example, the recruitment induced by PEEP is measured at a pressure of 20 cmH2O.

Adjuvant Therapy With Adjuvant Therapy With Ventilation used in ARDSVentilation used in ARDS

1- Prone Position1- Prone Position improves ventilation- improves ventilation-perfusion matching by:perfusion matching by:

Redistributing ventilation to area of better perfusion Redistributing ventilation to area of better perfusion

but not the reverse .but not the reverse .

More homogeneous end expiratory lung volume More homogeneous end expiratory lung volume (EELV) . (EELV) .

VIL.VIL.

2- Partial liquid ventilation (PLV) with 2- Partial liquid ventilation (PLV) with perfluorocarbons,perfluorocarbons, which carry oxygen. The which carry oxygen. The FRC is filled with the liquid, and the patient FRC is filled with the liquid, and the patient ventilated above it. PLV has the added advantage of ventilated above it. PLV has the added advantage of lavaging the airways and removing cellular debris.lavaging the airways and removing cellular debris.

Partial liquid ventilation (PLV) with perfluorocarbonsPartial liquid ventilation (PLV) with perfluorocarbons

3-3- High frequency oscillation:High frequency oscillation: full tidal volume full tidal volume ventilation, with no cyclic opening and closing of lung ventilation, with no cyclic opening and closing of lung units.units.

4- Tracheal gas insufflation:4- Tracheal gas insufflation: 2 or more litres of 2 or more litres of oxgen are delivered into the major bronchi in expiration oxgen are delivered into the major bronchi in expiration to wash out dead space gas.to wash out dead space gas.

5- Extracorporeal membrane oxygenation 5- Extracorporeal membrane oxygenation (ECMO)(ECMO)

Chronic Obstructive Chronic Obstructive Pulmonary Disease Pulmonary Disease

Chronic Obstructive Pulmonary Chronic Obstructive Pulmonary Disease ( COPD )Disease ( COPD )

COPD is a preventable and treatable disease with some COPD is a preventable and treatable disease with some significant extrapulmonary effects that may contribute significant extrapulmonary effects that may contribute to the severity in individual patients. Its pulmonary to the severity in individual patients. Its pulmonary component is characterized by airflow limitation that is component is characterized by airflow limitation that is not fully reversible and usually progressive. not fully reversible and usually progressive.

DiagnosisDiagnosis

..

Static Lung Static Lung VolumesVolumes

SeveritySeverity Post-Post-bronchodilator bronchodilator FEV1/FVCFEV1/FVC

FEV1 % predictedFEV1 % predicted

At riskAt risk >0.7>0.7 ≥≥8080

Mild COPDMild COPD <0.7<0.7 ≥≥8080

Moderate COPDModerate COPD <0.7<0.7 50-7950-79

Severe COPDSevere COPD

<0.7<0.7 30-4930-49

Very Severe Very Severe COPDCOPD

<0.7<0.7 <30 <30 oror 30-50 with Chronic 30-50 with Chronic Respiratory Failure symptomsRespiratory Failure symptoms

PathophysiologyPathophysiology

What is auto-PEEP?What is auto-PEEP?

Auto-PEEP is gas trapped in alveoli at end Auto-PEEP is gas trapped in alveoli at end expiration increased the work of breathing. expiration increased the work of breathing.

Auto PEEP exerts a positive pressure, and Auto PEEP exerts a positive pressure, and normal gas transit cannot be reestablished until normal gas transit cannot be reestablished until there is a pressure gradient from the mouth to there is a pressure gradient from the mouth to the alveoli. the alveoli.

Thus the patient must generate a much higher Thus the patient must generate a much higher negative inspiratory pressure to make the negative inspiratory pressure to make the pressure within negative with respect to pressure within negative with respect to atmospheric pressure.atmospheric pressure.

After the third breath, the airway was occluded at end-expiration After the third breath, the airway was occluded at end-expiration using the end-expiratory hold function on the ventilator. During using the end-expiratory hold function on the ventilator. During the period of zero flow, pressure in the alveoli and ventilator circuit the period of zero flow, pressure in the alveoli and ventilator circuit equilibrate, and the plateau pressure reflects auto or intrinsic equilibrate, and the plateau pressure reflects auto or intrinsic positive end-expiratory pressure (PEEPi), indicated by the arrowpositive end-expiratory pressure (PEEPi), indicated by the arrow ..

Giving CPAP to a patient who Giving CPAP to a patient who has auto-PEEPhas auto-PEEP

The increased work of breathing associated with auto-The increased work of breathing associated with auto-PEEP can be offloaded by applying CPAP to the PEEP can be offloaded by applying CPAP to the trachea/mouth, and splinting open the connecting trachea/mouth, and splinting open the connecting airways. airways.

The use of external PEEP in the setting of auto-PEEP may be The use of external PEEP in the setting of auto-PEEP may be

conceptualized by the "waterfall over a dam" analogy. In this analogy, conceptualized by the "waterfall over a dam" analogy. In this analogy, the presence of dynamic hyperinflation and 10 cmH20 of auto-PEEP is the presence of dynamic hyperinflation and 10 cmH20 of auto-PEEP is represented in the top panel by the reservoir of water trickling over represented in the top panel by the reservoir of water trickling over the dam represented by the solid block. In the middle panel, as long as the dam represented by the solid block. In the middle panel, as long as the external PEEP is less than or equal to the amount of auto-PEEP, the external PEEP is less than or equal to the amount of auto-PEEP, the amount of water in the upstream reservoir, representing dynamic the amount of water in the upstream reservoir, representing dynamic hyperinflation, does not increase. However, once the amount of water hyperinflation, does not increase. However, once the amount of water in the reservoir does increase (bottom panel), dynamic hyperinflation in the reservoir does increase (bottom panel), dynamic hyperinflation worsens. worsens.

THE FOUR COMPONENTS OF THE FOUR COMPONENTS OF COPD MANAGEMENTCOPD MANAGEMENT

1-Assess and monitor disease 1-Assess and monitor disease

2-Reduce risk factors2-Reduce risk factors

3-Manage stable COPD3-Manage stable COPD

-Education-Education

-Pharmacologic-Pharmacologic

-Non-pharmacologic-Non-pharmacologic

4-Manage exacerbations4-Manage exacerbations

Ventilation Strategy in COPDVentilation Strategy in COPD

1-The primary goal is to increase PaO2 to at least 60 mmHg and SaO2 1-The primary goal is to increase PaO2 to at least 60 mmHg and SaO2 90%.90%.

2-Tidal volumes (8-10 ml/kg). 2-Tidal volumes (8-10 ml/kg).

3-Minute ventilation (115 ml//kg). 3-Minute ventilation (115 ml//kg).

4-long expiratory times .4-long expiratory times .

5-High inspiratory flow allow short inspiratory time and therefore longer 5-High inspiratory flow allow short inspiratory time and therefore longer expiratory time for any given respiratory rate .expiratory time for any given respiratory rate .

6-Lower RR.6-Lower RR.

7- Volume control ventilation is more versatile than pressure control.7- Volume control ventilation is more versatile than pressure control.

As flow increased from 30 to 60 and 90 L/min (from right to left), As flow increased from 30 to 60 and 90 L/min (from right to left), frequency increased from (18 to 23 and 26 breaths/min, respectively), frequency increased from (18 to 23 and 26 breaths/min, respectively), Auto-PEEP decreased (from 15.6 to 14.4 and 13.3 cm H2O, Auto-PEEP decreased (from 15.6 to 14.4 and 13.3 cm H2O, respectively) and end-expiratory chest volume also fell. Increases in respectively) and end-expiratory chest volume also fell. Increases in flow from 30 L/min to 60 and 90 L/min also led to decreases in the flow from 30 L/min to 60 and 90 L/min also led to decreases in the swings in Pes from 21.5 to 19.5 and 16.8 cm H2O. swings in Pes from 21.5 to 19.5 and 16.8 cm H2O.

COPD flow and frequencyCOPD flow and frequency

What about OWhat about O22??

Long-term oxygen therapy in COPD :Long-term oxygen therapy in COPD :

PaO2PaO2 55 mm Hg or Sao2 55 mm Hg or Sao2 88 %. 88 %.

PaO2 between 55 and 60 mm Hg Sao2 PaO2 between 55 and 60 mm Hg Sao2 89 % with 89 % with evidence of evidence of pulmonary hypertensionpulmonary hypertension, , corcor pulmonalepulmonale, , or secondary or secondary erythrocytosiserythrocytosis (hematocrit >55%). (hematocrit >55%).

PaO2 PaO2 60 mm Hg or Sao2 60 mm Hg or Sao2 90 % for patients 90 % for patients whose room air PaO2 whose room air PaO2 55 mm Hg or SaO2 55 mm Hg or SaO2 88% 88% during exercise or sleep. during exercise or sleep.

Continuous low flow oxygen therapy , not more than Continuous low flow oxygen therapy , not more than 1 - 2L by nasal cannula, (for >15 hs/d) sufficient to 1 - 2L by nasal cannula, (for >15 hs/d) sufficient to correct hypoxemia has been shown to improve correct hypoxemia has been shown to improve survival. survival.

Mechanical VentilationMechanical Ventilation

A goal of mechanical ventilation is to A goal of mechanical ventilation is to prevent excessive work of breathing, prevent excessive work of breathing, while maintaining a work of breathing while maintaining a work of breathing that is sufficient to prevent respiratory that is sufficient to prevent respiratory muscle atrophy. This can be achieved by muscle atrophy. This can be achieved by using either using either NIPPV or IIPPVNIPPV or IIPPV..

Indication and Relative contraindication Indication and Relative contraindication for NIPPVfor NIPPV

Selection Criteria:Selection Criteria:

Moderate to severe dyspnea with the use of accessory muscles. Moderate to severe dyspnea with the use of accessory muscles. Moderate to severe acidosis PH Moderate to severe acidosis PH 7.35 and/or PaCO2 > 45 7.35 and/or PaCO2 > 45

mmHg. mmHg. RR > 25 breaths/min.RR > 25 breaths/min.

Exclusion Criteria: Exclusion Criteria:

Respiratory arrest.Respiratory arrest. Cardiovascular instability.Cardiovascular instability. High aspiration risk. High aspiration risk. Burn.Burn. Extreme obesity.Extreme obesity. Craniofacial trauma.Craniofacial trauma.

Advantages Of NIPPVAdvantages Of NIPPV

– Decreases need for invasive ventilation and Decreases need for invasive ventilation and

may be associated with improved outcome. may be associated with improved outcome.

– CPAP alone can reduce work of breathing in CPAP alone can reduce work of breathing in COPD during weaning and during sleep. COPD during weaning and during sleep.

– BiPAP weaning may be better than weaning BiPAP weaning may be better than weaning on pressure support via an ETT.on pressure support via an ETT.

Nocturnal bilevel ventilation:Nocturnal bilevel ventilation:

Is the use of NIPPV at two pressures (for Is the use of NIPPV at two pressures (for inhalation and exhalation) for at least 4 hours inhalation and exhalation) for at least 4 hours per night. per night.

The two pressures are usually referred to The two pressures are usually referred to IPAP IPAP and and EPAPEPAP. EPAP is a set pressure that has the . EPAP is a set pressure that has the same function as PEEP or CPAP and IPAP has same function as PEEP or CPAP and IPAP has the same function as pressure-support the same function as pressure-support ventilationventilation. .

Indications of IIPPV:Indications of IIPPV:

Hypoxemia that has not corrected with NIPPVHypoxemia that has not corrected with NIPPV Exclusion criteria of NIPPVExclusion criteria of NIPPV Sever acidosis PH<7.25 and/or PaCO2 >60 Sever acidosis PH<7.25 and/or PaCO2 >60

mmHgmmHg Impending respiratory arrestImpending respiratory arrest Respiratory rate > 36 breaths/minute Respiratory rate > 36 breaths/minute Use of all accessory muscles Use of all accessory muscles Thoracoabdominal paradox Thoracoabdominal paradox Even minor mental state changes Even minor mental state changes Patient's subjective sense of exhaustionPatient's subjective sense of exhaustion Cardiovascular instability Cardiovascular instability