Tracheal Saline Instillation: Effects in Patients With Lung Infection
ABSTRACT & COMMENTARY
Synopsis: In mechanically ventilated patients, instillation of normal saline solution had an adverse effect on SpO2, which persisted for up to 10 minutes.
Source: Ackerman MH, et al. Am J Crit Care 1998; 7:261-266.
In a prospective, randomized study, ackerman and associates determined the effect of endotracheal instillation of normal saline solution (NSS) before suctioning on oxygen saturation (SpO2), heart rate, and blood pressure in 29 patients with pulmonary infections. Pulmonary infection was defined as a change in the amount, color, and consistency of sputum; growth of infectious organisms on sputum cultures; evidence of infiltrates on chest radiographs; a WBC count of 12,000/mL or higher; and a body temperature of 39°C or higher.
Experimental subjects (n = 14) received a 5-mL bolus of NSS into the airway via the injection port of an in-line suctioning system, and control subjects (n = 15) did not. To simulate clinical practice, each subject was suctioned when deemed necessary by the staff nurse caring for the patient, and the number of suction passes was not controlled. Both groups were suctioned until their airways were clear as determined by the staff nurse. Suctioning was not preceded by preoxygenation or hyperinflation, in an effort to ensure uniformity in physiologic response to the procedure. Subjects were enrolled in the study for up to 12 hours, and data were collected from all suctioning episodes during this interval (mean, 5.0 + 2.2; range, 2-10 suctioning episodes).
After suctioning, SpO2 decreased for both groups. SpO2 returned to baseline within two minutes for the group that did not receive NSS, but remained less than baseline at 10 minutes post suctioning for the NSS group. Heart rate and blood pressure increased in both groups, but the changes were small and not clinically significant.
COMMENT BY LESLIE A. HOFFMAN, RN, PhD
Outcomes following NSS instillation have been assessed in several prior studies, and none have shown a clear clinical benefit. However, several of these studies were conducted in patients immediately following open heart surgery, a population unlikely to have required suctioning. Subjects in the present study all had evidence of a pulmonary infection, making them more likely to benefit. The major finding following NSS instillation was a decrement in SpO2, which persisted for 10 minutes.
NSS is commonly instilled prior to suctioning in patients with artificial airways. Proposed benefits include thinning and loosening secretions and stimulating a cough, thereby assisting secretion mobilization. There are a number of reasons why NSS instillation may not accomplish its intended benefits. Laboratory research has not shown that the viscosity of secretions decreases with the addition of NSS. NSS instillation may stimulate cough, but introduction of the suction catheter may accomplish the same outcome. Further, after NSS instillation patients are typically given extra breaths that likely propel secretions further down the airways and, thus, makes them more difficult to expel. There is also a risk of airway colonization from manipulation of the airway and tubing during the procedure. Thick and tenacious secretions are likely caused by inadequate systemic hydration or inadequate humidity in the ventilator circuit-problems that require different solutions.
Unfortunately, Ackerman and associates did not measure the volume or weight of secretions obtained following the intervention, so, it is not possible to determine if NSS caused a change in these variables. Since response can be individualized, it is also unfortunate that patients were not suctioned with and without NSS instillation, which would provide a more rigorous test of efficacy. Further, data were reported as change scores, making it difficult to determine the actual decrement in SpO2. Based on representative data for three subjects, the decrement ranged from 3-5% below baseline immediately after suctioning and from 1-4% below baseline 10 minutes after suctioning. Such changes would be clinically important.
Findings of this study add to the increasing number of studies that reported no benefit from NSS instillation. Until benefits are demonstrated, NSS instillation should be abandoned as a routine clinical practice.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content