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Gasometric parameters after tracheal aspiration in patients with septic shock: a clinical trial



Alexandra de Oliveira Matias Ferreira1,2, Monyque Evelyn dos Santos Silva3, Paula Dias Vidigal3, Maria Cecília Pereira Bosa1, Dalmo Valério Machado de Lima3

1Clementino Fraga Filho University Hospital / Federal University of Rio de Janeiro
2Pedro Ernesto University Hospital/State University of Rio de Janeiro
3Federal Fluminense University


Hypothesis: There is no hypoxemia after tracheal aspiration when there is no optimization of O2 pre-aspiration. Aim: To verify, through the assessment of arterial gasometry, if there is a significant difference in the values of SaO2, PaO2 and P/F in patients on ventilatory assistance and septic shock when FiO2 is not kept to 100% after tracheal aspiration. Method: a randomized clinical trial-type crossover, with two interventions, one arm, double-blind, phase III. A convenience sample of 27 patients is used by calculation for discrete variables of finite populations. Inclusion criteria: septic shock due to local infection, mechanical ventilation for more than 12 hours, optimal FiO2 <95%, PEEP <24 mmHg. For the statistical analysis we will use the student`s t-test with a significance level of 5% supported by software R version 2.5.1.
Keywords: Anoxia; Suction; Clinical Trial; Nursing; Intensive Care Units.



Randomized clinical trials have shown that the supply of 100% oxygen, before and after tracheal aspiration, in stable patients undergoing a ventilator weaning process, shows no significant differences in gasometric parameters and clinical results, a behavior which has not been tested in septic patients. Although tracheal aspiration is essential in caring for such patients, it has been done the same way since its creation in 1936(1). This technique aims to maintain airway patency, prevent infection, promote gas exchange, improve arterial oxygenation and improve lung function in patients who are intubated or tracheostomized with decreased level of consciousness, and have a diminished cough reflex. When there is an accumulation of secretions in the respiratory tract, the nurse must act to remove and/or facilitate the removal of this secretion(2).



Are there significant differences in gasometrical rates and in SpO2 in critically ill patients, when hyper oxygenation with FiO2 is not kept to 100% before tracheal aspiration, using as a parameter, the baseline physiological data?



There is no hypoxemia, comparing PaO2, SaO2, P/F and SpO2 after tracheal aspiration when the hyper oxygenation to 100% is not used before tracheal aspiration in critically ill septic patients.



To verify if there is a significant difference in the data with regard to SaO2, PO2, P/F and SpO2 in septic critically ill patients on mechanical ventilation, when the hyper oxygenation is not kept to 100% before tracheal aspiration.  This is demonstrated by comparing before and after aspiration gasometry data, according to baseline physiological data.


The tracheal aspiration without using the FiO2, for less than 15 seconds, and reconnection with mechanical ventilation between the aspiration is found to be as effective as the optimization of oxygen before the aspiration as a means of preventing hypoxemia.



Randomized clinical trial of crossover, one arm, double-blind, phase III. The data will be compared to two or more treatments or interventions in which subjects or patients, after completing a stage of treatment, will undergo other therapeutic interventions(3).
There will be a baseline for patient selection and pre-aspiration gasometry, named ideal gasometry. Randomization will be in groups of four patients, selected from a sequence of random numbers generated by the spreadsheet Microsoft Office Excel 2010 owned by Microsoft Corporation®. Group A will undergo aspiration FiO2 to 100% and group B will undergo aspiration without an increase in the FiO2 baseline. At the end of the experiment will be test a new gasometry test and then we will exchange groups. Tracheal aspiration is performed through an open system with catheter No. 14 using an aseptic technique. A Quartz Time® stopwatch will be used for timing.
Eligibility criteria: 18 years of age minimum, suffering from septic shock with a focus of local infection, mechanical ventilation for more than 12 hours, ideal FiO2 <95%; PEEP <24 mm / Hg. Surgical patients with Chronic Obstructive Pulmonary Disease Gold IV, patients receiving only palliative care, postpartum women and thrombocytopenic patients will be excluded.
The convenience sample of 21 patients was estimated by calculation for discrete variables of finite populations at a significance level of 0.05 and confidence interval of 95%.
The wasout time will be determined by auscultation to confirm the presence of tracheal secretions.
For the analysis of the tests an in vitro diagnostic cartridge, single use, disposable, with analyzers for human whole blood, will be used at the bedside.
The follow-up time is estimated at six months - August 2012 to February 2013 aiming to reach the n sample.



Student t-test for comparison of two-tailed paired samples adopting an α = 0.05 using the software R version 2.5.1 will be used.



The project was submitted to the Ethics Committee of the Federal University of Rio de Janeiro according to Resolution 196/96 of the National Health Council, approved with the number CAAE 04432812.0.0000.5257 and Protocol 061-12. Primary Registers of UTN WHO: U1111-1132-8681 in the Brazilian clinical trial registry project No. REQ: 796.



1. Martins I, Gutiérrez MGR. Nursing interventions for the nursing diagnosis ineffective airway clearance. Acta Paul Enferm. 2005;18(2):143-9

2. Rodrigues MVH. Estudo do comportamento hemodinâmico, da troca gasosa, mecânica, respiratória e da análise do muco brônquico na aplicação de técnicas de remoção de secreção brônquica em pacientes sob ventilação mecânica.  Tese [ doutorado em Cardiologia ]. Universidade de São Paulo; 2007.

3. Lima, DVM. Design of research: a contribution for authors. OnlineBraz J ofNursing. [ serial on the Internet ]. 2011 Oct; [ cited 2012 Aug 3 ] 10(2). Available from: http://www.objnursing.uff.br/index.php/nursing/article/view/3648


Project Data: Project from Professional Master Program in Nursing Care.
Financial Support for Research: Regional Nursing Council - RJ.


Received: 03/08/2012
Approved: 06/09/2012


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