Hypoxaemic Rescue Therapies In

ARDSReview of the evidence

Muhammad AbdelmoneimPSMMC-ICU

Is she in refractory hypoxemia?

Refractory HypoxemiaO Most studies in a general ARDS population and

many clinicians define refractory hypoxia as eitherO PaO2/FIO2 ratio < 100Or

O SaO2 < 88%Or

O PaO2 < 60 mmHg

With a plateau airway pressure > 30 cm H2O with a FIO2 > 0.8

 Lines of rescue therapiesO First line

O iNOO ProningO HFOVO Alveolar recruitment maneuvers

To prevent critical hypoxia, to allow ‘protective’ ventilation and to minimize organ

failure• Second line >> ECMO

Inhaled Nitric Oxide (iNO)

iNO showed no effects on mortality, regardless of hypoxemia severities.

Crit .Care Med 2014 Feb;42(2):404-12. doi: 10.1097/CCM.0b013e3182a27909.

iNO

O However iNO proved by many studies that it improves oxygenation

O Mostly started at 5 ppm and titrated up to 40 ppm to achieve optimal effect

O Optimal effect on oxygenation can usually be achieved with lower doses (5–10 ppm), whereas optimal effect on pulmonary artery pressure may require higher doses (up to 40 ppm)

Prone positioningO Patients with severe trauma and

ARDS O Often spend prolonged time in the

supine position, this tends to increase atelectasis and consolidation in the gravitational-dependent lung regions

O ARDS increases lung weight collapsing the dorsal regions of the lungs under the weight of the ventral regions

Prone positioning

• Prone positioning shifts the gravitational forces and reduces the cardiac compression of the lungs.

• Higher percentage of the lungs’ alveolar units are open to ventilation in the prone position than in the supine position.

• Air is distributed more homogeneously throughout the lungs, and stress and strain are decreased

•  Enhanced drainage of secretions from the posterior lung segments

Prone Positioning Effect

PROSEVA

The 28-day mortality was 16.0% in the prone group and 32.8% in the supine group (P<0.001). The hazard ratio for death with prone positioning was 0.39 (95% confidence interval [CI], 0.25 to 0.63) NNT 6

Prone positioning

When to stop proningO The criteria for stopping prone treatment are any

of the following (PROSEVA protocol): O Improvement in oxygenation (defined as a

PaO2:FiO2 ratio of ≥150 mm Hg, with a PEEP of ≤10 cm of water and an FiO2 of ≤0.6; in the prone group, these criteria had to be met in the supine position at least 4 hours after the end of the last prone session);

O A decrease in the PaO2:FiO2 ratio of more than 20%, relative to the ratio in the supine position, before two consecutive prone sessions; or complications occurring during a prone session and leading to its immediate interruption. proseva protocol.pdf

Prone positioning

Prone positioning

Complications leading to the immediate interruption of prone treatment included :

O Nonscheduled extubation, O Main-stem bronchus intubation, O Endotracheal-tube obstruction, O HemoptysisO Oxygen saturation of less than 85% on pulse oximetry O PaO2 of less than 55 mm Hg for more than 5 minutes when

the FiO2 was 1.0O Cardiac arrestO Heart rate of less than 30 beats per minute for more than 1

minute,O Systolic blood pressure of less than 60 mm Hg for more

than 5 minutesO Any other life-threatening reason for which the clinician

decided to stop the treatment.

Recruitment maneuvers and PEEP titration

O The most common RM used in protective ventilation strategies was a static RM of 40 cm H2O pressure for 40 s

O  However this RM method can be uncomfortable, may induce circulatory depression and has not been associated with improved outcomes in patients with ARDS

For patients with acute lung injury and acute respiratory distress syndrome, a multifaceted protocolized ventilation strategy designed to recruit and open the lung resulted in no significant difference in all-cause hospital mortality or barotrauma compared with an established low-tidal-volume protocolized ventilation strategy. This "open-lung" strategy did appear to improve secondary end points related to hypoxemia and use of rescue therapy

RM-PEEP

O Current evidence suggests that high PEEP regimes may have a survival benefit in patients with severe ARDS but there is insufficient evidence to establish the long term effects of recruitment maneuvers

O Recruitment maneuvers and PEEP titration are inexpensive, readily available and should be considered prior to other expensive or invasive rescue therapies in patients with refractory hypoxaemia

RM-PEEP

High frequency oscillatory ventilation (HFOV)

OSCILLATE

Conclusions In adults with moderate-to-severe ARDS, early application of HFOV, as compared with a ventilation strategy of low tidal volume and high positive end-expiratory pressure, does not reduce, and may increase, in-hospital mortality.

(HFOV)

Saudi Arabia: Riyadh: King Saud Bin Abdulaziz University for Health Science – Y.M. Arabi, H. Tlayjeh, O. Trinidad, O. Abahussein; Riyadh Armed Forces Hospital – Y. Mandourah, A. Abu

Daya, G. Hood, Q. Weber .

(HFOV)

(HFOV) OSCAR

(HFOV)

O LimitationsO expense of a separate ventilatorO The need for specific training in the use

of HFOV and circuit set-upO  Impaired clearance of pulmonary

secretionsO The need for heavy sedation and

neuromuscular blockade

(HFOV)

O Currently the place of oscillation in the rescue of hypoxaemic ARDS patients is unclear but it is usually commenced after other rescue therapies have been unsuccessful (iNO, RMs, PEEP).

O Depending on local experience and training many centers would then choose between prone positioning and oscillation as an additional rescue at this point?

O Although there is some evidence that oscillation when prone may also be efficacious, future studies are required to determine the true clinical place of such a strategy.

(HFOV)

Extra-corporeal membrane oxygenation (ECMO)

 provide non-pulmonary oxygen delivery and carbon dioxide removal and may also

facilitate lung protective ventilation in ARDS

(ECMO)

CESAR

(ECMO)

O The aim of CEZAR trial is to assess whether for patients with severe, but potentially reversible, respiratory failure, ECMO will increase the rate of survival without severe disability by six months post randomisation and will be cost effective from the viewpoints of the NHS and society, compared to conventional ventilatory support.

(ECMO)

O During ECMO, ventilator settings are gradually reduced to allow lung rest, i.e. peak inspiratory pressure 20 cm H2O, end expiratory pressure 10 cm H2O, rate 10 breaths per minute and FIO2 30%. ( 30,20,10,10)

O Anticoagulation is maintained with heparin to keep the activated clotting time (ACT) between 160 and 220 seconds. Patients are fed enterally or parenterally into the circuit, as indicated.

O Invasive procedures are avoided to reduce the risk of haemorrhage, and therefore any additional venous access necessary, e.g. for haemofiltration, is achieved via the circuit.

O Patients are diuresed to dry weight. O Haemoglobin concentrations are maintained at 14 g/dl, and

platelet counts are kept >100,000 per ml. O Patients are weaned from ECMO and decannulated when chest

X-ray appearance and lung compliance have improved, and adequate gas exchange without excessive ventilation (peak pressure less than 30 cmH2O, and FIO2 less than 60%) can be demonstrated during a 'trial-off' ECMO.

(ECMO) CEZAR protocol

O Main conclusions: O 6 month survival without disability: 63%

ECMO group vs. 47% conventional group NNT 6.

O Quality-adjusted life years at 6 months ('confined to bed' and 'unable to wash or dress'): ECMO group showed a gain of 0.03 gain

(ECMO)

ANZ-ECMO

During June to August 2009 in Australia and New Zealand, the ICUs at regional referral centers provided mechanical ventilation for many patients with 2009 influenza A(H1N1)-associated respiratory failure, one-third of whom received ECMO. These ECMO-treated patients were often young adults with severe hypoxemia and had a 21% mortality rate at the end of the study period

(ECMO)

Thanks