Selective PEEP in Acute Bilateral Lung Disease. Effect on Patients in the Lateral Posture

Abstract

Seven patients with acute respiratory failure due to diffuse and fairly uniform lung disease were studied during mechanical ventilation in the lateral decubital position with: (a) zero end-expiratory pressure (ZEEP) through a double-lumen oro-bronchial tube to permit a recording of the ventilation to each lung; (b) bilateral positive end-expiratory pressure (PEEP) of 1.2 kPa, with maintenance of ventilation distribution between lungs as observed during ZEEP; (c) selective PEEP of 1.2 kPa, applied to the dependent lung only, with ventilation as during ZEEP; and (d) conventional PEEP of 1.2 kPa applied to both lungs through a single-lumen tube, with free distribution of ventilation between the lungs. During ZEEP, 69% of ventilation was distributed to the non-dependent and 31% to the dependent lung; cardiac output was 6.51 X min-1, venous admixture (QS/QT) 40% and arterial oxygen tension (PaO2) 8.3 kPa. With bilateral PEEP, functional residual capacity (FRC) increased by 0.331, cardiac output was reduced to 5.11 X min-1 and venous admixture to 32%. PaO2 increased to 10.1 kPa. With selective PEEP the dependent lung FRC increased by 0.211 and the FRC of the non-dependent lung decreased by 0.081. Cardiac output increased to 6.11 X min-1, which was no longer significantly different from that during ZEEP. Venous admixture remained at the same level as with bilateral PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of body position and differential ventilation on lung dimensions and atelectasis formation in anaesthetized man

“…The effects of selective PEEP in the lateral position may be assumed to reduce shunt and ventilation/perfusion mismatch. Although the detailed effects of differential ventilation with selective PEEP on ventilation/ perfusion matching remain hypothetical at present, the net effect in terms of reduced venous admixture and improved arterial oxygenation has in fact been demonstrated in patients with acute respiratory failure (8) and in clinically lung healthy patients during anaesthesia (9). The findings in the present study point to morphological changes underlying such improvements.…”

“…8,9). During differential ventilation, the ventilators were electronically synchronized, thereby keeping the respiratory frequency equal and the start of inspiration simultaneous for both lungs.…”

“…Although the detailed effects of differential ventilation with selective PEEP on ventilation/ perfusion matching remain hypothetical at present, the net effect in terms of reduced venous admixture and improved arterial oxygenation has in fact been demonstrated in patients with acute respiratory failure (8) and in clinically lung healthy patients during anaesthesia (9). Although the detailed effects of differential ventilation with selective PEEP on ventilation/ perfusion matching remain hypothetical at present, the net effect in terms of reduced venous admixture and improved arterial oxygenation has in fact been demonstrated in patients with acute respiratory failure (8) and in clinically lung healthy patients during anaesthesia (9).…”

“…During differential ventilation with selective PEEP, a fixed tidal volume distribution with 50% of the total tidal volume going to each lung was used, combined with a PEEP of 1 kPa (10 cmH,O) to the dependent lung (cf. 8,9).…”

Capnography in the Intensive Care Unit

“…tion in cardiac output[99,100]. Opinions vary, however, as to the appropriate way to monitor improvement with PEEP therapy[101][102][103][104][105].Murray and colleagues[106] suggested that the PEEP level that results in the lowest PaF-1-co-) gradient is associated with the minimum intrapulmonary shunt value, without increasing dead space in a canine model of ARDS. Opinions vary, however, as to the appropriate way to monitor improvement with PEEP therapy[101][102][103][104][105].Murray and colleagues[106] suggested that the PEEP level that results in the lowest PaF-1-co-) gradient is associated with the minimum intrapulmonary shunt value, without increasing dead space in a canine model of ARDS.…”