Clinical Validation in Spain of Dysfunctional Ventilatory Weaning Response

PURPOSE

To validate clinically the diagnosis of dysfunctional ventilatory weaning response (DVWR) in order to determine the incidence and identify the defining characteristics and related factors.

METHODS

A descriptive, longitudinal, prospective study was carried out over 2 years using a nonprobability quota sample of 80 patients from 3 different university hospitals in Spain divided into two groups: Group A (patients with 24–72 hours of mechanical ventilation) and Group B (patients with >72 hours of mechanical ventilation). Observation, interview, physical examination, and chart review were used for data collection. Researchers designed an instrument to collect patient assessments. It was validated through a pilot study and included all the variables thought to be related with the phenomenon. A maximum of 10 observations per patient was made in a period of 5 days. Each observation took place in a framed time. At least two defining characteristics and a related factor had to be documented for the investigators to determine the existence of DVWR.

FINDINGS

The mean weaning time was 1.7 days (SD= 1.5). Based on research nurses' judgment, 70% (n= 57) of patients had DVWR. There was no difference in the incidence of DVWR between patients from Groups A and B. The 80 patients provided a total of 267 observations. DVWR occurred in 146 (55%) observations based on researchers' judgment, whereas DVWR was diagnosed in 48 observations (25%) based on clinical nurses' judgment.

DVWR at time 1 was indicated by indicators and factors in boldface were presented in more than one time shallow breathing, gasping breaths, adventitious breath sounds, deterioration in blood gases, increase in respiratory rate, blood pressure increase, heart rate increase, slight accessory respiratory muscles, apprehension, diaphoresis, inability to cooperate, hypervigilance, and fatigue. Related factors included a history of ventilatory dependence greater than 1 week, ineffective airway clearance, lack of trust in nurse, adverse environment, and anxiety. DVWR at time 2 was characterized by sleep pattern disturbance, pain, and having had previous DVWR were related factors. DVWR at time 3 included breathing discomfort, increase need for oxygen, agitation, and feeling warm. Related factors were perception of futility regarding own ability to be weaned. Indicators and factors in boldface were presented in more than one time. Adventitious breath sounds (OR= 9.2), adverse environment (OR= 21.9), and anxiety (OR= 43.12) were the variables resulting from logistic regression model.

DISCUSSION

Nurses do not recognize DVWR as frequently as researchers, who are very familiar with the weaning process but have not been trained to make a nursing diagnosis. It seems nurses associated the dysfunctional response only with the most severe manifestations. DVWR has a high incidence among patients who undergo a weaning process, regardless of the final outcome. History of ventilatory dependence >1 week has a protective effect against DVWR on day 1 of weaning. At time 1, the diversity of characteristics of DVWR was very broad, including severe manifestations. Although the risk of a new episode does not decrease, the severity appears to be milder in subsequent presentations. The nursing treatment received by the patient during the first episode of DVWR might have an influence on the response in the following attempts because most patients had only one episode. The increase in respiratory rate, heart rate, and systolic blood pressure was associated with DVWR at all three observation times. This may be related to the fact that all the mentioned variables were used as operational indicators of anxiety and this was the single related factor presented all the time. Adventitious breath sounds, adverse environment, and anxiety can be considered predictors of DVWR.

CONCLUSIONS

DVWR has a high incidence, although it is not well recognized by clinical nurses. Training nurses could increase the reliability of the diagnosis process in clinical practice. DVWR has different manifestations across the weaning process. Anxiety reduction, clearing the airway, and controlling environmental stimuli may prevent DVWR.