Indications and Contraindications for PEEP

Created on Tue, 06/16/2015 - 17:18
Last updated on Tue, 06/16/2015 - 18:36

ARDS:

  • There people have reduced aerated lung volume
  • Yes, it helps to set a high PEEP to increase the aerated lung volume
  • Yes, very high PEEP can cause VILI
  • No, nobody can agree on how high the PEEP should be

The ALVEOLI Trial: by ARDS network, (2004) - randomized 549 patients to high PEEP vs low PEEP.

  • Same volumes (around 6ml/kg) and plateau pressures; No survival benefit.
  • The investigators recommend you have a try of high PEEP ventilation, and if it improves the oxygenation of your ARDS patient, then you are a winner; and if it doesn’t work, don’t feel too bad, because there is no evidence it makes any difference in the long run anyway.

ASTHMA:

  • These people have an increased intrinsic PEEP and higher airway resistance. The main problem is high expiratory resistance, so it takes a while to empty the lungs.
  • Less responsive to PEEP than COPD
  • This is probably because there is too much intrinsic PEEP; plus mucus plugs might be blocking some of the airways, making them immune to the benefits of PEEP.
  • The result is that PEEP might actually cause worsening hyperinflation and increased gas trapping.
  • Some data suggests that low level PEEP is beneficial.

COPD:

  • These people have an increased intrinsic PEEP and higher airway resistance.
  • PEEP reduces the workload of respiratory muscles by counteracting both intrinsic PEEP and airway resistance
  • Also, it may actually splint the airways, resulting in improved emptying of the trapped gas.
  • No trials to test whether PEEP in COPD is of any use whatsoever. 

PULMONARY OEDEMA:

  • The main problem is a negative intrathoracic pressure generated due to decreased lung volume and decreased lung compliance
  • PEEP works directly on this problem.
  • Most people would agree that about 10cmH2O of PEEP is the standard of care for cardiogenic pulmonary oedema.

Contraindications to PEEP

  • Tension Pneumothorax  - it will get worse
  • Hypovolemic shock – cardiac output will decrease
  • Bronchopleural fistula -  it wont heal
  • High intracranial pressure - it will get higher
  • Right ventricular failure - the failing right ventricle may fail more with the addition of increased afterload

 

References

The National Heart, Lung, and Blood Institute ARDS Clinical Trials Network. Higher versus lower positive end-expiratory pressure in patients with the acute respiratory distress syndrome. NEnglJMed 2004; 351: 327–36.

Soni, N., and P. Williams. "Positive pressure ventilation: what is the real cost?." British journal of anaesthesia 101.4 (2008): 446-457.

Kumar, Anil, et al. "Continuous positive-pressure ventilation in acute respiratory failure: effects on hemodynamics and lung function." New England Journal of Medicine 283.26 (1970): 1430-1436.