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Gas exchange impairment induced by open suctioning in ARDS: impact of permissive hypercapnia

Background and aims

There is still controversy over the impact of open suctioning (OS) on gas exchange and the duration of suctioning. The goal of this physiologic study was to determine whether hypercarbia occurs following the use of OS in a lung lavage injured sheep and whether the level of baseline PaCO2 and duration of suctioning impacts gas exchange.


Six female sheep were lung injured by isotonic saline lavage until their PaO2 dropped to 100 mmHg on an FIO2 of 1.0, PEEP 5 cmH2O and VT 10 ml/kg. Then the VT was decreased to 6 ml/kg. RR was set to establish a PaCO2 of 40 mmHg or 80 mmHg. OS was performed on each animal. PaCO2 was randomly adjusted to 40 mmHg and 80 mmHg and the suction time randomly set at 10 s and 30 s. Before each of the four experimental conditions animals received recruitment maneuvers of 40 cmH2O CPAP for 40 s to establish a volume history, following by baseline for 15 min where FiO2 and PEEP were set based on the ARDSnet FiO2/PEEP [1]. OS was performed using a 14 Fr, TrachCare catheter at a pressure of -100 mmHg. Mean arterial blood pressure, heart rate, pulmonary and arterial wedge pressure, cardiac output, and arterial blood gases, were measured before, 1 min and then every 2 min after OS for 30 min.


During suctioning at 80 mmHg PaCO2 at both 10 s and 30 s suctioning times, the PaCO2 increased at 1, 15 and 31 min post suctioning (P < 0.05). PaCO2 also increased at 1 min when the baseline PaCO2 was 40 mmHg and the suction time was 30 s (P < 0.05) (Fig. 1). PaO2 decreased 1 min post suctioning in all conditions but recovered by 15 min. Hemodynamics did not demonstrate any significance differences regardless of the experimental condition.

Figure 1

Comparison of PaCO2 between groups.


OS causes in a significant increase in baseline PaCO2 during baseline hypercapnia and when suctioning is applied for 30 s. OS regardless of conditions results in a decrease in PaO2 that recovers rapidly post suctioning.


  1. 1.

    ARDS Network: N Engl J Med. 2000, 342: 1301-1308. 10.1056/NEJM200005043421801

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Caramez, M., Miyoshi, E., Harris, R.S. et al. Gas exchange impairment induced by open suctioning in ARDS: impact of permissive hypercapnia. Crit Care 9, P113 (2005).

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  • Isotonic Saline
  • Recruitment Maneuver
  • Lung Lavage
  • Exchange Impairment
  • Condition Animal