Positive end-expiratory pressure
Positive end-expiratory pressure (PEEP) is the pressure in the lungs (alveolar pressure) above atmospheric pressure (the pressure outside of the body) that exists at the end of expiration.[1] The two types of PEEP are extrinsic PEEP (PEEP applied by a ventilator) and intrinsic PEEP (PEEP caused by a non-complete exhalation). Pressure that is applied or increased during an inspiration is termed pressure support.
Intrinsic PEEP (Auto)
Auto (Intrinsic) PEEP — Incomplete expiration prior to the initiation of the next breath causes progressive air trapping (hyperinflation). This accumulation of air increases alveolar pressure at the end of expiration, which is referred to as auto-PEEP.
Auto-PEEP develops commonly in high minute ventilation (hyperventilation), expiratory flow limitation (obstructed airway) and expiratory resistance (narrow airway).
Once auto-PEEP is identified, steps should be taken to stop or reduce the pressure build-up[2]. When auto-PEEP persists despite management of its underlying cause, applied PEEP may be helpful if the patient has an expiratory flow limitation (obstruction)[3][4].
Extrinsic PEEP (Applied)
Applied (Extrinsic) PEEP — Applied PEEP is usually one of the first ventilator settings chosen when mechanical ventilation is initiated. It is set directly on the ventilator.
A small amount of applied PEEP (3 to 5 cmH2O) is used in most mechanically ventilated patients to mitigate end-expiratory alveolar collapse[5]. A higher level of applied PEEP (>5 cmH2O) is sometimes used to improve hypoxemia or reduce ventilator-associated lung injury in patients with acute lung injury, acute respiratory distress syndrome, or other types of hypoxemic respiratory failure[6].
Indications
Contraindications
Contraindications — There are no absolute contraindications to applied PEEP. However, applied PEEP can have adverse consequences (especially at high levels) and should be used cautiously in patients who have intracranial abnormalities, unilateral or focal lung disease, hypotension, hypovolemia, pulmonary embolism, dynamic hyperinflation without airflow limitation, or a bronchopleural fistula[9]. It may also have undesirable consequences in patients undergoing prone ventilation[10].
Complications
- Decreased venous return —
- Barotrauma — Pulmonary barotrauma is lung injury that results from the hyperinflation of alveoli past the rupture point.
- Increased intracranial pressure — In people with normal lung compliance, PEEP may increase the intracranial pressure (ICP) due to an impedance of venous return from the head[11].
- Alterations of Renal Functions and Water Metabolism — When PEEP is applied kidneys function in eliminating wastes, clearance of certain drugs, and regulating fluid, electrolyte, and acid-base balance is inhibited[12][13].
See also
References
- ^ thefreedictionary.com > positive end-expiratory pressure (PEEP) Citing: Saunders Comprehensive Veterinary Dictionary, copyright 2007
- ^ Caramez MP, Borges JB, Tucci MR, Okamoto VN, Carvalho CR, Kacmarek RM et al. (2005). "Paradoxical responses to positive end-expiratory pressure in patients with airway obstruction during controlled ventilation.". Crit Care Med 33 (7): 1519–28. PMC 2287196. PMID 16003057. http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16003057.
- ^ Smith TC, Marini JJ (1988). "Impact of PEEP on lung mechanics and work of breathing in severe airflow obstruction.". J Appl Physiol 65 (4): 1488–99. PMID 3053583.
- ^ Kondili E, Alexopoulou C, Prinianakis G, Xirouchaki N, Georgopoulos D (2004). "Pattern of lung emptying and expiratory resistance in mechanically ventilated patients with chronic obstructive pulmonary disease.". Intensive Care Med 30 (7): 1311–8. doi:10.1007/s00134-004-2255-z. PMID 15054570.
- ^ Manzano F, Fernández-Mondéjar E, Colmenero M, Poyatos ME, Rivera R, Machado J et al. (2008). "Positive-end expiratory pressure reduces incidence of ventilator-associated pneumonia in nonhypoxemic patients.". Crit Care Med 36 (8): 2225–31. doi:10.1097/CCM.0b013e31817b8a92. PMID 18664777. http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18664777.
- ^ Smith, RA. Physiologic PEEP. Respir Care 1988; 33:620.
- ^ Eremenko AA, Borisov RIu, Egorov VM (2011). "[Evaluating the effectiveness of "open lung" maneuvre].". Anesteziol Reanimatol (3): 43-7. PMID 21851022.
- ^ Hillman NH, Nitsos I, Berry C, Jane Pillow J, Kallapur SG, Jobe AH (2011). "Positive end-expiratory pressure and surfactant decrease lung injury during initiation of ventilation in fetal sheep.". Am J Physiol Lung Cell Mol Physiol 301 (5): L712-20. doi:10.1152/ajplung.00157.2011. PMID 21856815. http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21856815.
- ^ Hasan FM, Beller TA, Sobonya RE, Heller N, Brown GW (1982). "Effect of positive end-expiratory pressure and body position in unilateral lung injury.". J Appl Physiol 52 (1): 147–54. PMID 7037709.
- ^ Huynh T, Messer M, Sing RF, Miles W, Jacobs DG, Thomason MH (2002). "Positive end-expiratory pressure alters intracranial and cerebral perfusion pressure in severe traumatic brain injury.". J Trauma 53 (3): 488-92; discussion 492-3. doi:10.1097/01.TA.0000025657.37314.2F. PMID 12352486.
- ^ Frost EA (1977). "Effects of positive end-expiratory pressure on intracranial pressure and compliance in brain-injured patients.". J Neurosurg 47 (2): 195-200. doi:10.3171/jns.1977.47.2.0195. PMID 327031.
- ^ Kaczmarczyk G (1994). "Pulmonary-renal axis during positive-pressure ventilation.". New Horiz 2 (4): 512-7. PMID 7804800.
- ^ Dehne MG, Meister M, Röhrig R, Katzer C, Mann V (2010). "Effects of inverse ratio ventilation with PEEP on kidney function.". Ren Fail 32 (4): 411-6. doi:10.3109/08860221003672176. PMID 20446776.
External links