Closed versus partially ventilated endotracheal suction in extremely preterm neonates: physiologic consequences

Summary

This randomized cross over study aimed to compare the severity and incidences of desaturation and bradycardia between the partially ventilated endotracheal suction method (PVETS) and closed tracheal suction system (CTSS) in extremely preterm neonates. Fifteen intubated and ventilated extremely low birth weight preterm infants (mean birth weight 689 g) randomly underwent both suction techniques within a 12-h period to obtain a paired reading group. The process was repeated 24–48 h apart until three pairs of reading groups were collected. Changes in oxygen saturation measured with pulse oximetry and heart rate changes measured with electrocardiogram were recorded using Hewlett-Packard m240A monitor trending software. The mean of each parameter's variation from baseline was obtained using SPSS descriptive statistics and analyzed using SPSS repeated measures ANOVA. Fisher Exact Test was used to analyze the incidence of desaturation and bradycardia. The closed tracheal suction system reported a significantly smaller degree of oxygen saturation fall (P < 0.005) and significantly fewer incidences of desaturation. There was also a significantly smaller degree of heart rate reduction although episodes of bradycardia were not significantly different between the two methods. Oxygen saturation and heart rate were significantly more stable during the use of CTSS compared to PVETS in the extremely low birth weight preterm population.

Introduction

Endotracheal suction (ETS) is an essential but potentially hazardous supportive procedure for patients requiring mechanical ventilation. Suction induced responses are especially deleterious in extremely preterm neonates with immature pulmonary, and systemic haemodynamic function (Fenichel, 1990, Fiascone and Vreeland, 1997, Greenough, 1999, Greenough and Roberton, 1999). Of most concern is the immature haemodynamic regulatory function, which makes this group of patients very susceptible to serious conditions induced by hypoxemic and/or bradycardic events. Immediate complications of ETS include atelectasis, hypoxemia, bradycardia, disturbed central haemodynamics and mucosal trauma (Durand et al., 1989, Kerem et al., 1990, Shah et al., 1992, Simbruner et al., 1981, Walsh et al., 1989). This is especially pronounced in extremely low birth weight neonates (Greenough and Roberton, 1999). Episodic hypoxemic and bradycardic events have been implicated, individually or in combination, in cerebral haemodynamic fluctuations that can lead to the development of serious cerebral morbidities (Livera et al., 1991, Low et al., 1993). Continuous and immediate assessment of the parameters that reflect these two events are essential in studies aiming to investigate or reduce ETS induced complications.

Conventional methods of ETS often involve complete interruption of ventilation. Recently, experimental studies have focused on the use of techniques that permit mechanical ventilation during ETS, such as the partially ventilated endotracheal suction (PVETS) method, which incorporates special adaptors that allow partial mechanical ventilation to continue during the insertion of the suction catheter. One of the newest technological developments for facilitating ETS and reducing associated complications is the closed (multi-use catheter) tracheal suction system (CTSS). Both the PVETS and the CTSS have separately demonstrated potential in reducing the severity and incidences of hypoxemia and bradycardia when compared to the open method (Cabal et al., 1979, Graff et al., 1987, Gunderson et al., 1986, Mosca et al., 1997). However, no published prospective study to date has been carried out to compare the two techniques within the same group of subjects. Several physiologic, infection control, financial and time saving advantages have been cited by manufacturers and by centres that use CTSS (Paul-Allen and Octrow, 2000, Wright and Askin, 1996). The advantages, however, have not been substantiated by rigorous clinical research in the extremely preterm population.

The aim of this study was to compare heart rate (HR) and oxygen saturation (SpO₂) changes between the PVETS and CTSS in an extremely low birth weight neonatal cohort using a randomized cross over design. We hypothesized that there would be significantly less variation in the SpO₂ and HR parameters with the use of CTSS compared to PVETS.