Related factors of the nursing diagnosis ineffective breathing pattern in an intensive care unit

Objective to identify the predicting factors and sensitivity, specificity, positive and negative related value of nursing diagnosis Ineffective Breathing Pattern among patients of an intensive care unit. Method cross-sectional study. A logistic regression was fitted to assess the simultaneous effects of related factors. Results among the 120 patients, 67.5% presented Ineffective Breathing Pattern. In the univariate analysis, the related factors were: group of diseases, fatigue, obesity and presence of bronchial secretion, and the defining characteristics were: changes in respiratory depth, auscultation with adventitious sounds, dyspnea, reduced vesicular murmurs, tachypnea, cough and use of the accessory musculature to breathe. The mean age of patients with was higher than those without this diagnosis. The defining characteristics reduced murmurs had high sensitivity (92.6%), specificity (97.4%), negative related value (86.4%) and positive related value (98.7%). The related factors of Ineffective Breathing Pattern were the related factors fatigue, age and group of diseases. Conclusion fatigue, age and patients with a group of diseases were related factors of Ineffective Breathing Pattern in this study. Reduced vesicular murmurs, auscultation with adventitious sounds and cough may be defining characteristics to be added in the international classification, as well as the related factors bronchial secretion and group of diseases.


Introduction
The evaluation of the breathing pattern is essential to define nursing interventions and care plan to meet the patients' needs. This evaluation is performed through a physical examination, monitoring the physiological functions of chest examination, palpation, pulmonary percussion and auscultation, which provide objective data on the use of respiratory muscles, respiratory rate and lung sounds (1)(2) .
In normal conditions, the breathing pattern satisfies the need for oxygenation of the body. However, situations where there is fatigue, airway impairment due to secretion and decreased pulmonary expansion characterize the nursing diagnosis (ND) ineffective breathing pattern (IBP) (3) .
The ND ineffective breathing pattern (IBP) was first defined in 1980 and revised in 1996, 1998, 2010 and 2017. In 2017, this diagnosis was modified and included associated conditions. This diagnosis focuses on problem and belongs to domain 4, class 4, activity/ rest of the NANDA International, Inc. (NANDA-I). IBP is defined as an inspiration and/or expiration pattern that does not provide sufficient ventilation (4) .
This diagnosis has often been identified in adult individuals and in several units. In trauma patients treated at an university hospital in the city of São Paulo, Brazil, it was observed that 82.4% presented IBP (5) and 85.7% in adults who receive care in emergency rooms (6) .
In adult patients with heart disease, it was observed that this diagnosis was present in 70.6% and that 100.0% of them presented fatigue as a related factor (RF) and dyspnea as a defining characteristic (DC) (7) .
The first American survey identified the Nursing Diagnosis IBP in 81.0% of intensive care patients (8) . In the city of Rio Branco, Acre (AC), Brazil, a prevalence of 64.4% of IBP was identified in an Intensive Care Unit (ICU) patients (9) however, these studies evaluated only the prevalence, did not identify the measures of accuracy and also did not evaluate the predicting factors of the IBP nursing diagnosis. Thus, it is observed that the nursing diagnosis IBP is very frequent in ICUs. Due to the importance of early identification and the establishment of a care plan for these patients, the objective of the present study was to identify the predicting factors and to April 2016. The sample size was calculated by the formula for finite populations, using a 95% confidence coefficient; a random error of 5%; IBP prevalence of 64.4%, according to a study carried out at an ICU of the city of Rio Branco (9) , and the population of  (10)(11) .
The independent study variables (DC, RF and associated conditions) were identified in the NANDA-I, classification for the Nursing diagnosis IBP (4) and in a literature review (age, smoking, group of diseases, bronchial secretion, cough, reduce vesicular murmurs and auscultation with adventitious sounds) (12) . These selected variables were evaluated only by the main investigator of the study through interviews and physical examinations in the patients' bed, according to the conceptual and operational definition of each variable, in which some were previously validated (13)(14)(15) and others were adapted for the adult population,  (12) , auscultation with adventitious sounds (12) , and reduced vesicular murmurs (4,12) .
The related factors of IBP evaluated were: anxiety, pain, fatigue, respiratory muscle fatigue, hyperventilation, obesity, position of the body that prevents lung expansion, and bronchial secretion (4,12) .
The RF age, smoking and a group of diseases were also included (12) .
The associated conditions of IBP evaluated were: chest wall deformity, bone deformity, musculoskeletal damage and hypoventilation syndrome (4 for women (22) . The maximum inspiratory pressure was obtained through manovacuometry (10) and is a simple way to measure maximum respiratory pressures, and a quantitative measure of respiratory muscle function and strength, which indicates if ventilation is adequate.
The DC decreased inspiratory pressure evaluated by the manovacuometer was chosen to confirm the presence of IBP because a study conducted in 2015 and 2016 with 626 adult ICU patients showed that this DC and the RF fatigue were the ones that had the greatest sensitivity for the IBP diagnosis in these patients (23) .
The nurse responsible for this research collected the data with aid of a standardized collection instrument prepared for this purpose. Collection was performed every day in the morning with patients who met the inclusion criteria in the ICU. After the data collection, the patients presenting and not presenting the IBP nursing diagnosis were compared to the causality of IBP nursing diagnosis.
For manovacuometry, the subjects were evaluated in the seated position (90º), using a nasal clip and semirigid rubber, diver type, with a internal hole of 2 mm diameter, in which the patient was asked to seal his lips firmly around the mouthpiece. In order to measure the maximal inspiratory pressure (MIP), the patient was asked to exhale, and at that moment the researcher occluded the orifice of the device and then the patient made a maximal inspiratory effort against the occluded airway, which was recorded on the manovacuometer.
Patients would maintain the inspiratory pressure for at least 1.5 seconds and the highest sustained negative pressure was recorded. This same process was repeated three times, with one-minute intervals in each evaluation, and only the highest value was used (11) .
It is emphasized that if differences of values greater than 10% were obtained between measurements, they were discarded. The association between two categorical variables was verified using the Chi-square test, or the Fisher's exact test in cases of small samples. When differences were observed in the distributions, standardized adjusted residues were used to identify local differences.
Comparison of means between two groups was performed using Student's t-test for independent samples.
For all defining characteristics and related factors of dichotomous nature, accuracy measurements were presented through sensitivity, specificity, positive related value (PPV) and negative related value (NPV).
Logistic regressions were fitted to evaluate the simultaneous effects of RF on the presence of IBP. Due to the large number of variables that predicted the size of the sample, the variables whose associations with the dependent variable were significant at 20% in the univariate analysis were selected for the initial models.
Then the non-significant variables at 5% were excluded one by one in order of significance (backward method).

Discussion
The related factors of the nursing diagnosis IBP in the studied ICU were fatigue, age, and group of diseases (cardiocirculatory diseases, trauma and other diagnoses). The development of fatigue is an important and common complication in many patients admitted to ICUs and its incidence may range from 30% to 60% in these patients (11,24) . Fatigue has been investigated in many studies because of its high prevalence and the damage caused to the patients' quality of life (18,(25)(26)(27) . Besides previous co-morbidities, several factors may contribute to fatigue, including systemic inflammation, use of some medications such as corticoids, sedatives and neuromuscular blockers, malnutrition, hyperosmolarity, parenteral nutrition, cardiopathies and prolonged immobility, common conditions in the ICU (25)(26) . Fatigue can be present in patients with diverse pathologies, such as heart, lung, hematological, and oncological diseases, as well as in patients presenting pain, malnutrition and psychological manifestations such as anxiety and depression, which also corroborates the other RF found in this study, that is, group of diseases (27) .
Other factors that may contribute to the onset of fatigue are age and number of comorbidities (17) .

Regarding the number of morbidities, studies have
shown an association between greater number of morbidities and greater perception of fatigue (28)(29) . In the elderly, fatigue occurs due to changes in the body as a whole and in the cardiopulmonary system, in which reduction of oxygen uptake, reduction of respiratory muscle strength, and increase of vascular resistance are observed. In the muscular system, there is a decrease in muscle strength and flexibility, resulting in fatigue, which affects simple activities of daily life of the elderly (30) .   A recent study, also performed in an ICU in the city of Ribeirão Preto, SP, Brazil, with 626 adult patients, showed that the RF fatigue presented greater sensitivity for the IBP diagnosis (23) . The authors emphasize that IBP patients present DC related to ventilatory dysfunction and, if not treated adequately, this diagnosis may evolve to the diagnosis of impaired spontaneous ventilation (ISV), characterizing a worse prognosis of the patient (23) .

Univariate model Final multivariate model
Old age was the second predictor of IBP in this study. Ageing is characterized by a chronic decrease in the functions of the organic system, leaving the elderly susceptible to diseases, with risk to trigger the IBP diagnosis (2) . Ageing leads to physiological changes such as compromised gas exchange efficiency, reduced pulmonary compliance, decreased respiratory muscle strength, and decreased oxygen transport to tissues, resulting in decreased cardiac output, body mass, alveolar volume and ventilation/perfusion ratio, which may lead to the emergence of the Nursing diagnosis IBP (20) .
In this sense, it is up to nurses to recognize these peculiarities and alterations during the physical examination and to select interventions that improve the respiratory state within the expected for the age. A cross-sectional study conducted in Rio Grande do Sul, Brazil, identified that almost half of the elderly (42.0%) had IBP (31) . In this study, 86.7% of elderly patients presented IBP. It is also worth mentioning that this group of patients is more vulnerable to influenza due to the higher prevalence of chronic degenerative diseases and immunological deterioration, which may cause breathing changes and the manifestation of IBP (31)(32)(33)(34) .
The third related factor of IBP was group of diseases (trauma, cardiocirculatory diseases, and other diagnoses). External causes, as an important cause of traumas, represented by traffic accidents, represent a serious public health problem in Brazil and are responsible for high morbidity and mortality, disability rates, and sequelae, not to mention considerable economic cost (35) .
A study that analyzed 406 trauma victims in the city of São Paulo, SP, Brazil, identified a prevalence of 82.8% of patients with IBP (5) .
Another study performed in the urgency and emergency unit of a large public hospital in southern Brazil identified a prevalence of 51.2% of IBP in patients who had been victims of multiple traumas, the main ones being pain, skeletal muscle damage, hyperventilation and neuromuscular dysfunction, and the main DC was tachypnea and bradypnea (36) . The presence of develop IBP (36)(37) .
In relation to the group of diseases related to the Without intervention, this will lead to respiratory muscle fatigue and consequent IBP diagnosis (17) . Other related factors (obesity and bronchial secretion), although not identified as predictors of IBP in our study, have been also associated with this diagnosis.
It was also observed that the DC changes in respiratory depth, auscultation with adventitious sounds, dyspnea, reduced vesicular murmurs, tachypnea, cough and use of accessory respiratory muscles were also associated with IBP (12)(13)(14)19) .
In obese individuals, IBP diagnosis is detected by the reduced lung volume and capacity in these patients.
Excessive adipose tissue also causes mechanical compression of the diaphragm, resulting in restrictive respiratory insufficiency, decreased pulmonary compliance and increased pulmonary resistance, which consequently increases respiratory work and oxygen, resulting in the IBP diagnosis (38)(39) .
The RF bronchial secretion possibly related to the Nursing diagnosis IBP due to the narrowing of the lumen as consequence of the exacerbated production of secretions and also due to the inability of intensive care patients to expel secretions spontaneously from the respiratory tract, leading to respiratory difficulty and to the IBP diagnosis (12) .
The DC dyspnea, tachypnea, changes in respiratory depth and use of accessory muscles to breathe are very common alterations among patients with IBP.
This is due to respiratory muscle weakness and nonresolution of the underlying problem that led in the first place to respiratory decompensation. Tachypnea is the Rev. Latino-Am. Enfermagem 2019;27:e3153.
result of pulmonary hyperventilation, which develops as an adaptive compensation attempt (18) . The failure of this compensatory mechanism and the imbalance between the demand and the supply of oxygen favor the appearance of the IBP diagnosis (40)(41) . The use of the accessory musculature demonstrates the attempt to reestablish a normal breathing pattern. A study carried out in the city of Fortaleza, CE, Brazil, identified that the use of the accessory musculature brings a seven-fold higher chance of having the IBP diagnosis (15) . of chronic diseases such as asthma, chronic obstructive pulmonary disease (COPD) and rhinosinusitis (42) , which can cause changes in pulmonary ventilation, leading the individual to present the IBP diagnosis. A cross-sectional study carried out in Fortaleza, CE, Brazil, showed that the IBP diagnosis was the most prevalent and the most common DC were adventitious respiratory sounds and cough (43) . Adventitious respiratory sounds are detected in pulmonary auscultation and are common in patients with respiratory changes in ICUs (12) .
When assessing the specificity, sensitivity and positive and negative related values of DC and RF, it was observed that the DC reduced vesicular murmurs had an association and an excellent measure of accuracy, presenting sensitivity, specificity, positive related value and negative high values for the nursing diagnosis IBP.
Despite its importance, the DC reduced vesicular murmurs is not part of the NANDA-I classification for this nursing diagnosis. Vesicular murmurs are normal sounds auscultated in the lungs and their decrease is pathological and may indicate the presence of atelectasis and even decreased lung expansion (44) . Atelectasis is a respiratory complication caused by the obstruction of a bronchus, or lung, by secretion or solid bodies that prevent the flow of air and lead to a decrease in the number of alveoli worked (44) . When there is complete obstruction in a bronchus that supplies air to a normally ventilated region of the lung parenchyma, the gas in the alveoli distal to the obstruction is absorbed into the pulmonary circulation. Once all the alveolar gas is absorbed into the circulation, the alveoli, now without gas, collapse, generating a decrease in vesicular murmurs and causing changes in the respiratory ventilation and ineffective breathing pattern (44) .