Ventilation Literature Summaries

OVERVIEW

• summaries of key papers from the ventilation literature
• NIV
• ARDS
• Tracheostomy
• Weaning

NON-INVASIVE VENTILATION (NIV)

Lightowler JV1 Wedzicha JA, Elliott MW, Ram FS. Non-invasive positive pressure ventilation to treat respiratory failure resulting from exacerbations of chronic obstructive pulmonary disease: Cochrane systematic review and meta-analysis. BMJ. 2003 Jan 25;326(7382):185. [PMC140272]

• 8 studies
• patients with hypercapnic respiratory failure from an exacerbation of COPD
• NIV vs standard care
  -> reduced mortality
  -> reduced need for intubation

Masip J, Roque M, Sánchez B, Fernández R, Subirana M, Expósito JA. Noninvasive ventilation in acute cardiogenic pulmonary edema: systematic review and meta-analysis. JAMA. 2005 Dec 28;294(24):3124-30. [PMID 16380593]

• systematic review (15 trials)
• CPAP vs BIPAP in APO
  -> decreased mortality in CPAP group

Mehta S et al. Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary edema. Crit Care Med. 1997 Apr;25(4):620-8. [PMID 9142026]

• BIPAP vs CPAP
• APO -> prematurely terminated after only 27 patients as increased risk of MI in BIPAP group
• criticisms: unmatched groups with a higher incidence of patients with chest pain in BIPAP group

Other indications for NIV with less compelling evidence =

• -> pneumonia in the immunosuppressed
• -> isolated chest trauma with rib #’s + regional analgesia
• -> acute-on-chronic hypercapnic respiratory failure due to chest wall deformity or neuromuscular disease
• -> acute asthma

Nava S et al. Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med. 2005 Nov;33(11):2465-70. [PMID 16276167]

• MRCT
• n = 97
• inclusion criteria: ventilated for more than 48 hours + risk of developing post extubation respiratory failure (hypercapnia, CHF, weak cough, secretion retention, co-morbidities, upper airway obstruction)
• extubation to NIV for atleast 8 hours VS extubation to O2
  -> significant reduction in re-intubation rate
  -> extubate high risk patients to NIV (data no so convincing for extubating everyone to NIV)

Esteban, A. et al (2004) “Noninvasive Positive-Pressure Ventilation for Respiratory Failure after Extubation” NEJM 350:2452-60

• MRCT
• 37 centers (8 countries)
• n = 221
• extubated after at least 48 hours of MV who developed respiratory failure within 48 hours -> NIV vs standard medical therapy
  -> trial stopped early because of increased mortality in NIV group (risk of death: NIV group 25% and invasive group 14% -> absolute risk increase = 11% -> NNH 10)
  -> in unselected patients NIV didn’t prevent re-intubation, it delayed it and was associated with a higher rate of death!

Weaknesses

• waited until respiratory failure developed prior to instituting NIV
• unselected patients
• contamination from cross over to the NIV group

Ferrer M et al. Non-invasive ventilation after extubation in hypercapnic patients with chronic respiratory disorders: randomised controlled trial. Lancet. 2009 Sep 26;374(9695):1082-8 [PMID 19682735]

• RCT
• single center (Spain)
• n = 106
• inclusion criteria: ventilated with chronic respiratory disorders and hypercapnia (>45mmHg) after a successful spontaneous breathing trial -> NIV for 24 hours vs O2
• primary end point: avoidance of respiratory failure after extubation
  -> respiratory failure less likely in patients assigned to NIV (ARR 33% -> NNT 3)
  -> NIV group had a lower 90 day mortality (ARR 20% -> 5)

Weaknesses

• ICU length of stay not changed -> it could be argued that you should just keep them ventilated for longer and wait until their hypercapnic respiratory failure resolves!

ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)

• See Acute Respiratory distress Syndrome (ARDS) Literature Summaries

TRACHEOSTOMY

Griffiths J et al. Systematic review and meta-analysis of studies of the timing of tracheostomy in adult patients undergoing artificial ventilation. BMJ. 2005 May 28;330(7502):1243 [PMC558092]

• systematic review of randomized and controlled studies looking at early tracheostomy VS later tracheostomy VS prolonged endotracheal intubation
• 15,950 articles -> 5 papers analysed
• n = 406
  -> no difference in mortality or risk of pneumonia
  -> significant difference in duration of MV and ICU stay

WEANING

Brochard L et al. Comparison of three methods of gradual withdrawal from ventilatory support during weaning from mechanical ventilation. Am J Respir Crit Care Med. 1994 Oct;150(4):896-903. [PMID 7921460]

• RCT
• n = 109
• inclusion criteria: deemed ready for weaning, failed to sustain 2 hours on a T piece
• SIMV vs PSV vs further T piece sessions
  -> significant increase in number of patients successfully weaned on PSV

Esteban A et al. A comparison of four methods of weaning patients from mechanical ventilation. Spanish Lung Failure Collaborative Group. N Engl J Med. 1995 Feb 9;332(6):345-50. [PMID 7823995]

• -> one daily spontaneous breathing trials are equally as effective as multiple daily trials
• -> spontaneous breathing trials led to extubation 3 times more rapidly than SIMV and 2 times as quickly as PSV

Girard TD et al. Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial. Lancet. 2008 Jan 12;371(9607):126-34 [PMID 18191684]

• 4 Centers is North American
• RCT – 2003-2006
• inclusion criteria: > 18 years, on MV for > 12 hours
• exclusion criteria: post cardiac arrest, moribund, > 2 weeks ventilatory support, severe dementia, co-enrolled in another trial
• intervention = SBT vs SAT -> SBT
• primary end points = ventilator free days
• secondary end points = delirium, 28 day -> 1 year mortality, length of stay in ICU and hospital
• n = 334 (powered of 80%)
• intention to treat analysis
• Results
  -> reduction in ventilator free days
  -> reduced mortality at 1 year
  -> similar delirium rates but less coma
  -> increased risk of extubation
  -> however, risk of re-intubation same in control arm
  -> higher rate of successful extubation
  -> lower trachestomy rate

Strengths

• protocolised
• multi-centre

Weaknesses

• not blinded
• not generalisable to Australasia (North America has Ventilator Technician)
• surgical patients not enrolled
• sedation time and practice not recorded