Landmark articles on ventilation

Transcription

1 Landmark articles on ventilation Dr Shrikanth Srinivasan MD,DNB,FNB,EDIC Consultant, Critical Care Medicine Medanta, The Medicity

2 ARDS

3 AECC DEFINITION-1994 ALI Acute onset Bilateral chest infiltrates PCWP 18mm Hg or absence of clinical e/o LA hypertension PaO2 : FiO2 ratio 300 ARDS PaO2 : FiO2 ratio 200 And all the above Independent of PEEP Bernard et al, Am J Respir CCM; 1994;149:818-24

4 Shortcomings of AECC Defination Confusion relating to ALI No explicit criteria for defining acute leading to ambiguity regarding cases of acute-on-chronic hypoxemia. High interobserver variability in interpreting chest X-rays. Difficulties identifying / ruling out cardiogenic or hydrostatic pulmonary edema, especially in an era of plummeting pulmonary artery catheter use. PaO2 / FiO2 ratio is sensitive to changes in ventilator settings

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6 Berlin definition of acute respiratory distress syndrome Timing Chest imagining a Origin of oedema Oxygenation b Mild Within 1 week of a known clinical insult or new/worsening respiratory symptoms Bilateral opacities not fully explained by effusion, lobar/lung collapse, or nodules Respiratory failure not fully explained by cardiac failure or fluid overload; need objective assessment (for example, echocardiography) to exclude hydrostatic oedema if no risk factor present 200 <PaO 2 /FiO 2 < 300, with PEEP or CAP > 25 cmh 2 O c CPAP, continuous positive airway pressure;fio 2, fraction of inspired oxygen; PaO 2, partial pressure of arterial oxygen; PEEP, positive end-expiratory pressure. a Chest X-ray or computed tomography scan. b If altitude higher > 100 m, correction factors should be made as follows: PaO 2 /FiO 2 X (barometric pressure / 760). C this may be delivered non-invasively in the mild acute respiratory distress syndrome group. Adapted with permission from[9]. Moderate 100 <PaO 2 /FiO 2 < 200, with PEEP > 5 CmH 2 ) Severe PaO 2 /FiO 2 < 100, with PEEP > 5 cmh 2 O ARDS Definition task force: Acute respiratory distress syndrome: The Berlin Definition. JAMA 2012, 307:

7 Salient Differences Acute lung injury no longer exists.pao2/fio = mild ARDS. Acute onset of ARDS : within 7 days of some defined event, which may be sepsis, pneumonia, or simply a patient s recognition of worsening respiratory symptoms. Bilateral opacities consistent with pulmonary edema must be present ; may be detected on CT or chest X-ray. No need to exclude heart failure in the new ARDS definition; patients LV failure can coexist with ARDS. An objective assessment meaning an echocardiogram in most cases if there is no clear risk factor present

8 Is it any better? Compared with the AECC definition, the final Berlin Definition had better predictive validity for mortality, with an area under the ROC of (95% CI, ) vs (95% CI, ;P<.001) Gordon D. Rubenfeld, MD,JAMA. 2012;307(23):doi: /jama

9 CONCLUSIONS: The present study did not validate the Berlin definition of ARDS. Neither the stratification by severity nor the PaO2/FiO2 at study entry was independently associated with mortality Intensive care Med (2013) 39;

10 Low Tidal Volume Ventilation

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12 Summary Study design: Enrolled 861 patients and compared traditional ventilation treatment (initial tidal volume of 12 ml/kg PBW) and a Pplat of 50 cm of H2O, with ventilation with a lower tidal volume (initial tidal volume of 6 ml/kg PBW and a Pplat 30 cm of H2O. Primary outcome: death before a patient was discharged home and was breathing without assistance. Second primary outcome: ventilator-free days from day 1 to day 28.

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15 Summary Results The trial was stopped after the enrollment of 861 patients because mortality was lower in the group treated with lower tidal volumes than in the group treated with traditional tidal volumes (31.0 percent vs percent, P=0.007) Low TV ventilation reduces absolute mortality by about 7-9%, number needed to treat of between The number of days without ventilator use during the first 28 days after randomization was greater in this group (12±11 vs. 10±11; P=0.007).

16 Summary Conclusions In patients with acute lung injury and the acute respiratory distress syndrome, mechanical ventilation with a lower tidal volume than is traditionally used results in decreased mortality and increases the number of days without ventilator use.

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19 High PEEP or Low PEEP

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21 Summary Objectives To evaluate the association of higher vs lower PEEP with patient-important outcomes in adults with acute lung injury or ARDS who are receiving ventilation with low tidal volumes and to investigate whether these associations differ across prespecified subgroups. Involved analysis of 3 trials: ALVEOLI, LOVS and EXPRESS

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23 From: Higher vs Lower Positive End-Expiratory Pressure in Patients With Acute Lung Injury and Acute Respiratory Distress Syndrome: Systematic Review and Meta-analysis JAMA. 2010;303(9): doi: /jama For patients with ARDS at baseline: higher PEEP group had lesser mortality (34.1% vs 39.1%; P =.049) and more likely to achieve unassisted breathing earlier (64.3% vs 57.8%); For patients without ARDS at baseline: the RR for death in hospital with higher vs lower PEEP was higher (27.2% vs 19.4%) and the time to unassisted breathing proportions at 28 days was more, 70.1% vs 80.9%) Date of download: 6/17/2015

24 Summary Conclusions Treatment with higher vs lower levels of PEEP was not associated with improved hospital survival. However, higher levels were associated with improved survival among the subgroup of patients with ARDS. High PEEP is unlikely to benefit in patients with less severe lung injury; indeed, a strategy of treating these patients using high PEEP levels may be harmful.

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26 Summary Objective To compare an established low-tidal-volume ventilation strategy (target TV of 6 ml/kg of PBW, Pplat 30 cm H 2 O, and conventional levels of PEEP (n = 508) with an experimental strategy based on the original openlung approach, combining low tidal volume, lung recruitment maneuvers, and high positive-end expiratory pressure (target TV of 6 ml/kg PBW + Pplat 40 cm H 2 O + recruitment maneuvers, and higher PEEP)(n = 475)

27 From: Ventilation Strategy Using Low Tidal Volumes, Recruitment Maneuvers, and High Positive End-Expiratory Pressure for Acute Lung Injury and Acute Respiratory Distress Syndrome: A Randomized Controlled Trial JAMA. 2008;299(6): doi: /jama Figure Legend: Patients were censored at hospital discharge and at death in the 2 analyses, respectively. Date of download: 6/17/2015 Copyright 2015 American Medical Association. All rights reserved.

28 Summary Main Outcome Measure All-cause hospital mortality. Conclusion: Higher PEEP provided no benefit in 28-day mortality (28 vs 32%, p = 0.2). This open-lung strategy did appear to improve secondary end points related to hypoxemia (reduced refractory hypoxia (~5% vs. 10%, p = 0.01) and use of rescue therapies This results, in combination with the 2 other major trials could justify use of higher PEEP levels as an alternative to the established low-peep, low-tidal-volume strategy

29 PRONING

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31 Summary Multicenter, randomized trial in France and Spain, 466 patients Included patients with early, severe ARDS Early = within 36 hours of meeting ARDS criteria Severe = PaO 2 :FiO 2 ratio < 150 mm Hg (with FiO 2 of at least 60%, PEEP 5 cm H 2 0, and tidal volume of 6 ml/kg ideal weight) All patients underwent a hour stabilization period to verify inclusion criteria prior to randomization Prone positioning was conducted for at least 16 consecutive hours per day in standard ICU beds. Primary outcome: All cause mortality within 28 days after inclusion

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33 Summary Proning was stopped once the patient met oxygenation requirements while supine for at least four hours (PaO 2 :FiO mm Hg with PEEP 10 and FiO2 60 Results Prone positioning significantly reduced 28-day all-cause mortality compared to supine positioning (16% vs 32.8%,NNT 6, p<0.001). 17% Absolute risk reduction Proning also reduced 90-day mortality (23.6% vs. 41%, NNT 6, p<0.001) No increase in adverse events

34 Summary Conclusion This trial showed that patients with ARDS and severe hypoxemia (as confirmed by a Pao2:Fio2 ratio of <150 mm Hg, with an Fio2 of 0.6 and a PEEP of 5 cm of water) can benefit from prone treatment when it is used early and in relatively long sessions

35 Current Role of HFOV

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37 Summary Methods In a multicenter, RCT conducted at 39 intensive care units in five countries, we randomly assigned adults with new-onset, moderate-to-severe ARDS to HFOV targeting lung recruitment or to a control ventilation strategy targeting lung recruitment with the use of low tidal volumes and high PEEP Primary outcome was the rate of in-hospital death from any cause.

38 Summary Result: Trial stopped after 548 of a planned 1200 patients had undergone randomization in view of consistent trend towards harm. In-hospital mortality was 47% in the HFOV group, as compared with 35% in the control group (relative risk of death with HFOV, 1.33; 95% CI, 1.09 to 1.64; P = 0.005) More and longer need for sedation and vasoactive drugs in HFOV group

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40 Summary 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 endexpiratory pressure, does not reduce, and may increase, in-hospital mortality

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42 Role of ECMO

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44 Summary Objective: RCT To evaluate the safety, clinical efficacy, and cost-effectiveness of extracorporeal membrane oxygenation (ECMO) compared with conventional ventilation support. Subjects: 180 adults aged years with severe (Murray score >3.0 or ph <7.20) but potentially reversible respiratory failure

45 Summary Primary outcome was death or severe disability at 6 months after randomization or before discharge from hospital. Primary analysis was by intention to treat Results 766 patients were screened; 180 were enrolled and randomly allocated to consideration for treatment by ECMO (n=90 patients) or to receive conventional management (n=90) 68 (75%) patients actually received ECMO 63% (57/90) of patients allocated to consideration for treatment by ECMO survived to 6 months without disability compared with 47% (41/87) of those allocated to conventional management (relative risk 0.69, p=0.03).

46 The absolute risk reduction for the primary outcome was 16%, which translates into a number-needed-to-treat of 6.2 patients

47 Summary Conclusions We recommend transferring of adult patients with severe but potentially reversible respiratory failure, whose Murray score exceeds 3.0 or who have a ph of less than 7.20 on optimum conventional management, to a centre with an ECMO-based management protocol to significantly improve survival without severe disability. This strategy is also likely to be cost-effective in settings with similar services to those in the UK

48 Areas of Uncertainty It is not clear which patients with ARDS are the best candidates for this treatment or which is the most favourable timing for the initiation of ECMO? The intervention in CESAR was referral to an ECMO centre not treatment with ECMO. In fact, only 75% of ECMO-referred patients actually received ECMO Lack of a management protocol for patients randomized to conventional treatment Would the results be replicable in smaller or less experienced centres Should we exclude patients who have required more than 7 days of high-pressure or high-fio2 ventilation from receiving ECMO.

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50 Summary Methods Multicenter, double-blind trial enrolled 340 patients, with an onset of severe ARDS within the previous 48 hours were randomly assigned to receive, for 48 hours, either cisatracurium besylate (178 patients) or placebo (162 patients). Severe ARDS was defined as a ratio of the PaO2/FiO2) <150, with a PEEP of 5 cm H2O and a tidal volume of 6 to 8 ml/kg PBW. Primary outcome : 90-day in-hospital mortality rate

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52 Summary Results The crude 90-day mortality was 31.6% in the cisatracurium group and 40.7% in the placebo group (P = 0.08). Mortality at 28 days was 23.7% with cisatracurium and 33.3% with placebo (P = 0.05). The rate of ICU-acquired paresis did not differ significantly between the two groups

53 Summary Conclusions In patients with severe ARDS, early administration of a neuromuscular blocking agent improved the adjusted 90-day survival and increased the time off the ventilator without increasing muscle weakness

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55 Summary Study design Multicenter, double-blind, parallel-group trial Randomized 400 adults at intermediate to high risk of pulmonary complications after major abdominal surgery to either nonprotective mechanical ventilation or a strategy of lung-protective ventilation. Low tidal volume mechanical ventilation (LTV) ml/kg IBW; PEEP 6-8 cm H2O; recruitment maneuvers every 30 minutes Ordinary mechanical ventilation -- tidal volume ml/kg PEEP and recruitment maneuvers were not protocolized but could be provided at the anesthesiologist's discretion Primary outcome: a composite of major pulmonary and extrapulmonary complications occurring within the first 7 days after surgery.

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57 Summary Results: Major postop complications (within 1 week after abdominal surgery): 27.5% of the patients receiving larger tidal volumes, but only in 10.5% of LTV. Postop acute respiratory failure: 5% of patients in the LTV group required invasive or NIV in the week after surgery, compared to 17% in the conventional ventilation group -- a 69% relative risk reduction. Pulmonary complications (pneumonia, atelectasis, ARDS, respiratory failure): 17.5% of patients receiving LTV had of any type, compared to 36% in the conventional ventilation group. 30-day mortality was similar in both groups (~3%), but hospital stays were slightly shorter in LTV. There was no apparent harm from low tidal volume mechanical ventilation.

58 Summary CONCLUSIONS As compared with a practice of nonprotective mechanical ventilation, the use of a lungprotective ventilation strategy in intermediate-risk and high-risk patients undergoing major abdominal surgery was associated with improved clinical outcomes and reduced health care utilization

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61 Sherpa Neto et al, Curr Opin Crit Care 2015, 21:65 73

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66 Early or Late Tracheotomy

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68 Summary Objective To test whether early vs late tracheostomy would be associated with lower mortality in adult patients requiring mechanical ventilation in ICU. Study Design Multicentered RCT enrolled 909 adult patients on mechanical ventilation for less than 4 days and identified by the treating physician as likely to require at least 7 more days of mechanical ventilation. Patients were randomized 1:1 to early tracheostomy (within 4 days) or late tracheostomy (after 10 days if still indicated). Primary outcome measure was 30-day mortality.

69 Summary Results Early tracheostomy group: 91.9% received a tracheostomy late tracheostomy group: 44.9% received a tracheostomy. All-cause 30 days mortality was 30.8% in the early and 31.5% in the late group (absolute risk reduction for early vs late, 0.7%). Two-year mortality was 51.0% in the early and 53.7% in the late group (P =.74). Median critical care unit length of stay in survivors was 13.0 days in the early and 13.1 days in the late group (P =.74). Tracheostomy-related complications were reported for 6.3% of patients (5.5% in the early group, 7.8% in the late group).

70 Summary Conclusions Early tracheostomy within 4 days of critical care admission was not associated with an improvement in 30-day mortality or other important secondary outcomes. The ability of clinicians to predict which patients required extended ventilatory support was limited.