Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets

Abstract

Summary. Introduction Non-bronchoscopic bronchoalveolar lavage is an alternative to diagnostic bronchoscopy in pediatric patients, as fiberoptic bronchoscopes with aspiration channels are too large for small infants. There are many variations of the method in clinical practice, and saline instillation followed by open endotracheal suctioning is still commonly used. Lung function can deteriorate with these procedures, and we have investigated the effects on lung mechanics and oxygenation in healthy piglets. Methods The lungs of anesthetized and mechanically ventilated piglets were recruited with CPAP 35 cmH 2 O. Thereafter we instilled 5 ml of saline into the endotracheal tube, followed by three breaths from the ventilator. Saline was retrieved through a suction catheter wedged far distally in the airway. The procedure was followed by a new recruitment maneuver. Complete inspiratory/expiratory pressure-volume loops (PV-loops) were obtained just before and 5 min after saline instillation. Arterial blood gases were collected at equivalent times in 14 similar piglets submitted to exactly the same procedure. Results The inspiratory limb of the PV-loops changed markedly, as the lower inflection point was displaced towards higher pressures (P ¼ 0.004), and hysteresis measured at 15 and 30 cmH 2 O increased (P ¼ 0.004 and P ¼ 0.012, respectively). Although PaO 2 decreased significantly (P ¼ 0.001), values after saline instillation/ suctioning were still in the high normal range, that is, 22.2 AE 2.6 kPa. Conclusions Opening pressures of the lungs increase markedly after saline instillation/suctioning in healthy piglets. In this situation, adequate recruitment maneuvers and PEEP might prevent lung collapse and deteriorations in arterial oxygenation.

Positive pressure ventilation: what is the real cost?

“…40 113 136 Medical intervention such as lavage effectively removes surfactant impairing regional and whole lung compliance. 29 Surfactant dysfunction changes compliance and exaggerates heterogeneous lung inflation necessitating ventilation patterns which may cause further damage. 11 30 69 123 Surfactant has a role in the immune defences of the lung.…”

Does a solitary lobar collapse give pressure–lung volume relationship similar to that found in acute respiratory distress syndrome? A porcine experimental study

“…In isolated degassed normal animal lungs immersed in liquid and contained in a plethysmograph, inflation and deflation of air induce significant hysteresis and a ÔkneeÕ, Pflex or lower inflexion point (LIP), on the inflation limb of PV curves, whereas inflation and deflation with saline give no or minimal hysteresis and no LIP, suggesting the importance of surface tension for producing hysteresis (Mead et al, 1957;Bachofen et al, 1970). On the other hand, hysteresis is minimal in in vivo studies of the lung in healthy humans or animals, indicating that the in vitro findings might be caused by changes in lung vitality or loss of surfactant (Jonson et al, 1993;Bitzen et al, 2004;Cunha-Goncalves et al, 2007;Koefoed-Nielsen et al, 2008). Indeed, in animals with surfactant-depleted lungs and in patients with ALI ⁄ ARDS, PV curves have both a significant hysteresis and a LIP (Matamis et al, 1984;Bernard et al, 1994;Ranieri et al, 1994;Amato et al, 1998;Albaiceta et al, 2004Albaiceta et al, , 2005Bitzen et al, 2006;Koefoed-Nielsen et al, 2008).…”

ETCare: a randomized, controlled, masked trial comparing two solutions for upper airway care in the NICU

“…[1][2][3][4][5] The practice of instilling saline as part of endotracheal tube suctioning is intended to enhance removal of thick secretions that can restrict gas flow through the endotracheal tube. Saline is also occasionally used to periodically clear the nasal passages of neonates on nasal continuous positive airway pressure.…”

“…1 Neonatal Intensive Care, McKay-Dee Hospital Center, Intermountain Healthcare, Ogden, UT, USA; 2 Respiratory Therapy Department, LDS Hospital, Intermountain Healthcare, Salt Lake City, UT, USA; 3 Neonatal Intensive Care, LDS Hospital, Intermountain Healthcare, Salt Lake City, UT, USA; 4 Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA; 5 Pharmacy Department, McKay-Dee Hospital Center, Intermountain Healthcare, Salt Lake City, UT, USA; 6 Pharmacy Department, LDS Hospital, Intermountain Healthcare, Salt Lake City, UT, USA and 7 Biostatistics and Data Center, LDS Hospital, Intermountain Healthcare, Salt Lake City, UT, USA Objective: Small quantities of normal saline are sometimes instilled into the endotracheal tube of intubated neonates, to assist with the removal of thick secretions and maintain patency of the endotracheal tube. However, saline is detrimental to the innate immune system of the upper airway mucosa, rapidly unfolding and inactivating antimicrobial peptides such as LL-37.…”