Distribution of volatile organic compounds by distance from industrial complexes and potential health impact on the residents.

Volatile organic compounds (VOCs) are the air pollutants emitted from the petrochemical industry known to pose adverse health effects on workers. The database based on the third phase of The Environmental Health Study in the Korean National Industrial Complexes (EHSNIC) in Ulsan conducted from 2018 to 2021 was used. Subjects were divided into the exposed and control group according to the estimated pollution level and distances from the industrial complexes. Ambient benzene, ethylbenzene, and xylene were significantly higher in the exposed group compared to the controls, as well as their metabolites. Risk of chronic disease and atopic dermatitis was higher in the exposed group which was supported by higher serum inflammatory markers and high hazard index of the exposed region. These results can draw attention to people engaged with environmental plans and used as primary data when making policies to reduce pollutant levels around industrial complexes.

The relationship between self-reported sensory decline and cognitive frailty in older persons.

This study aimed to explore the relationship between self-reported sensory decline, including poor hearing and vision, and cognitive frailty in older persons. This cross-sectional study analyzed data from the 2020 National Survey of Living Conditions and Welfare Needs of Older Koreans. Binomial logistic regression analysis was performed to analyze the relationship between self-reported sensory decline and cognitive frailty. Of 9,692 participants, 39.8 % experienced sensory decline. The prevalence of cognitive frailty was 15.7 % among participants with poor hearing, 6.9 % among those with poor vision, and 17.9 % among those with combined poor hearing and vision. In our model, adjusted for sociodemographic and health-related variables, the cognitive frailty was significantly associated with poor hearing alone and combined poor hearing and vision. The findings suggest that healthcare professionals should prioritize their attention to the risk of cognitive frailty in older adults experiencing poor hearing alone and combined with poor vision.

Post-acute COVID-19 syndrome in previously hospitalized patients.

INTRODUCTION: With the prolongation of the COVID-19 pandemic, more individuals are experiencing sequelae after COVID-19 infection, also known as post-acute COVID-19 syndrome (PCS). The aims of this study were to describe the prevalence and characteristics of PCS symptoms such as fatigue, anxiety, and depression and to compare these symptoms according to participant characteristics in patients who had been previously hospitalized due to COVID-19. DESIGN: A descriptive cross-sectional study design was used. METHODS: We included 114 individuals who had been hospitalized for COVID-19 and were discharged from the hospital at least 4 weeks before. Symptoms were assessed using the Fatigue Severity Scale, the Hospital Anxiety-Depression Scale, and the PCS symptom questionnaire developed by the authors. We used descriptive statistics, the Student's t-test, the Wilcoxon rank-sum test, and the Kruskal-Wallis test for statistical analyses. RESULTS: The most prevalent symptoms were anxiety (66.7%), fatigue (64.0%), headache (57.9%), and concentration or memory difficulties (57.9%). Concentration or memory difficulties and sleep disturbances had the highest mean frequency. Concentration or memory difficulties were rated with the highest mean severity, and cough, loss of taste, and muscle and joint pain had the highest mean distress scores. Female participants, individuals hospitalized for more than 2 weeks, individuals discharged more than 9 months ago, unvaccinated patients, and those who tried at least one symptom relief method reported higher symptom distress. CONCLUSION: The findings of this investigation into the frequency, severity, and distress of symptoms shed light on the identification of post-COVID symptoms in detail. To objectively evaluate and comprehend the symptom trajectories of PCS, prospective studies about the development of symptom assessment tools and studies with a longitudinal design should be conducted. CLINICAL RELEVANCE: A substantial number of respondents reported numerous symptoms and expressed symptom distress; therefore, the development of nursing interventions and treatments to alleviate PCS symptoms is crucial.

Silent struggles to self-manage high blood pressure among deaf sign language users: a qualitative study.

AIMS: Tailored self-management support of hypertension, considering language and communication, is important for minorities, specifically in the deaf community. However, little is known about the experiences of hypertension self-management in deaf individuals who use sign language. This study aimed to explore the factors and processes of self-management in deaf sign language users with hypertension. METHODS AND RESULTS: Ten men and women who used sign language participated in this study. Data were collected using in-depth personal interviews conducted in the presence of a sign language interpreter between November 2022 and February 2023. All interviews were recorded and transcribed for conventional content analysis. Qualitative analyses identified four categories related to the self-management of hypertension among participants: personal factors (chronic hand pain, unique language and communication, and efforts to turn crisis into opportunities), family and socioeconomic factors (family support and financial burden of living), challenges (limited health literacy and alienation from health education), and desire for health education considering the deaf community. CONCLUSION: The results of this study suggest that family support, socioeconomic status, hand pain, and health literacy should be considered for the planning and development of health education on self-management of hypertension in deaf individuals. In addition, this health education requires cooperation with qualified sign language interpreters in healthcare settings.

Prenatal to peripubertal exposure to Di(2-ethylhexyl) phthalate induced endometrial atrophy and fibrosis in female mice.

Di(2-ethylhexy) phthalate (DEHP) is a widely used plasticizer that is ubiquitously found in the environment. Using a mouse model, we investigated the impact of early life DEHP exposure ranging from the prenatal to peripubertal developmental period of the female reproductive system. Pregnant female mice were allocated to three groups as follows: control, 100 mg/kg/day, and 500 mg/kg/day DEHP treatment. DEHP exposure was introduced through feeding during pregnancy (3 weeks) and lactation (3 weeks). After weaning, the offspring were also exposed to DEHP through feeding for another 2 weeks. Observations were conducted on female offspring at 10 and 24 weeks. The number of live offspring per dam was significantly lower in the high-DEHP-exposed group (500 mg/kg/day) compared to the control group (7.67 ± 1.24 vs. 14.17 ± 0.31; p < 0.05) despite no difference in pregnancy rates across the groups. Low-DEHP exposure (100 mg/kg/day) resulted to a decreased body weight (36.07 ± 3.78 vs. 50.11 ± 2.11 g; p < 0.05) and decreased left uterine length (10.60 ± 1.34 vs. 14.77 ± 0.82 mm; p < 0.05) in 24-week- old female mice. As early as 10 weeks, endometrial atrophy and fibrosis were observed, and endometrial cystic hyperplasia was noted in female mice at 24 weeks. Our study is the first to demonstrate that female mice exposed to DEHP in the early life developed endometrial fibrosis in the female offspring. Further studies on the consequences of these observations in fecundity and other reproductive functions are warranted.

Associations with smartphone usage and life satisfaction among older adults: Mediating roles of depressive symptoms and cognitive function.

This study aimed to investigate the serial mediating effects of depressive symptoms and cognitive function on the relationship between smartphone usage and life satisfaction among older people. Multiple linear regression analyses for complex randomly sampled data were used to identify the association between the status/level of smartphone usage, depressive symptoms, cognitive function, and life satisfaction. Furthermore, the Sobel test was conducted to assess the serial mediating effects of depressive symptoms and cognitive function on the relationship between smartphone usage and life satisfaction. The status and level of smartphone usage had significant positive impacts on cognitive function and life satisfaction, and negative impacts on depressive symptoms. Our results suggest that nurses should assess the status and level of smartphone usage among older people and plan approaches that enable them to utilize various smartphone functions to improve the well-being of this population.

Development of a robust daily soil temperature estimation in semi-arid continental climate using meteorological predictors based on computational intelligent paradigms.

Changes in soil temperature (ST) play an important role in the main mechanisms within the soil, including biological and chemical activities. For instance, they affect the microbial community composition, the speed at which soil organic matter breaks down and becomes minerals. Moreover, the growth and physiological activity of plants are directly influenced by the ST. Additionally, ST indirectly affects plant growth by influencing the accessibility of nutrients in the soil. Therefore, designing an efficient tool for ST estimating at different depths is useful for soil studies by considering meteorological parameters as input parameters, maximal air temperature, minimal air temperature, maximal air relative humidity, minimal air relative humidity, precipitation, and wind speed. This investigation employed various statistical metrics to evaluate the efficacy of the implemented models. These metrics encompassed the correlation coefficient (r), root mean square error (RMSE), Nash-Sutcliffe (NS) efficiency, and mean absolute error (MAE). Hence, this study presented several artificial intelligence-based models, MLPANN, SVR, RFR, and GPR for building robust predictive tools for daily scale ST estimation at 05, 10, 20, 30, 50, and 100cm soil depths. The suggested models are evaluated at two meteorological stations (i.e., Sulaimani and Dukan) located in Kurdistan region, Iraq. Based on assessment of outcomes of this study, the suggested models exhibited exceptional predictive capabilities and comparison of the results showed that among the proposed frameworks, GPR yielded the best results for 05, 10, 20, and 100cm soil depths, with RMSE values of 1.814°C, 1.652°C, 1.773°C, and 2.891°C, respectively. Also, for 50cm soil depth, MLPANN performed the best with an RMSE of 2.289°C at Sulaimani station using the RMSE during the validation phase. Furthermore, GPR produced the most superior outcomes for 10cm, 30cm, and 50cm soil depths, with RMSE values of 1.753°C, 2.270°C, and 2.631°C, respectively. In addition, for 05cm soil depth, SVR achieved the highest level of performance with an RMSE of 1.950°C at Dukan station. The results obtained in this research confirmed that the suggested models have the potential to be effectively used as daily predictive tools at different stations and various depths.

Understanding health literacy of deaf persons with hypertension in South Korea: A cross-sectional study.

BACKGROUND: Health literacy is strongly associated with health inequality among persons with deafness, and hypertension (HTN) is the most prevalent chronic disease among persons with deafness in South Korea. Despite its importance, research regarding the health literacy levels of persons with deafness with HTN in South Korea is lacking. This study aimed to comprehensively assess the health literacy levels of persons with deafness with HTN in South Korea, including linguistic, functional, and internet health literacy. METHODS: In this descriptive cross-sectional study, 95 persons with deafness with HTN were recruited through facilities associated with the deaf community. From August 2022 to February 2023, data were collected through face-to-face surveys attended by a sign language interpreter and online surveys. The data were analyzed using descriptive statistics and Spearman's correlation. RESULTS: Approximately 62.1% of the participants exhibited a linguistic health literacy level corresponding to less than that of middle school students, and the total percentage correct of functional health literacy was 17.9%. Each domain of internet health literacy was low. Significant correlations were found between some aspects of health literacy. CONCLUSIONS: The study's findings highlight the low health literacy levels across various facets among persons with deafness with HTN in South Korea. Based on these findings, several strategies are suggested for developing HTN self-management interventions for persons with deafness. This study contributes to the foundational understanding of health literacy among persons with deafness with HTN in South Korea and provides valuable insights and guidance for developing HTN self-management interventions.

Unveiling the Diversity of Hydnum in the Republic of Korea with One New Species, Hydnum paucispinum.

Hydnum is a genus of ectomycorrhizal fungi belonging to the Hydnaceae family. It is widely distributed across different regions of the world, including North America, Europe, and Asia; however, some of them showed disjunct distributions. In recent years, with the integration of molecular techniques, the taxonomy and classification of Hydnum have undergone several revisions and advancements. However, these changes have not yet been applied in the Republic of Korea. In this study, we conducted an integrated analysis combining the morphological and molecular analyses of 30 specimens collected over a period of approximately 10 years in the Republic of Korea. For molecular analysis, the sequence data of the internal transcribed spacer (ITS) region, the large subunit of nuclear ribosomal RNA gene (nrLSU), and a portion of translation elongation factor 1-α (TEF1) were employed as molecular markers. Through this study, we identified eight species that had previously not been reported to occur in the Republic of Korea, including one new species, Hydnum paucispinum. A taxonomic key and detailed descriptions of the eight Hydnum species are provided in this study.

Exercise as an antidepressant: exploring its therapeutic potential.

The COVID-19 pandemic has increased the prevalence of depressive disorders worldwide, requiring alternative treatments beyond medication and psychotherapy. Exercise has positive effects on the brain; therefore, it has emerged as a promising therapeutic option for individuals with depression. Considerable research involving humans and animals offers compelling evidence to support the mental health benefits of physical activity or exercise mediated by the regulation of complex theoretical paradigms. However, challenges such as conducting long-term follow-up assessments and considering individual characteristics remain in human studies despite extensive efforts. While animal studies provide valuable insights into the potential benefits of exercise and its impact on outcomes related to depression and anxiety in rodents exposed to different stress paradigms, translating the findings to humans requires careful evaluation. More research is needed to establish precise exercise prescription guidelines and to better understand the complex relationship between exercise and depressive disorders. Therefore, this concise review explores the evidence supporting exercise intervention as an antidepressant treatment and its underlying mechanisms.

Similarities and Differences of Interventions to Promote Physical and Psychological Health Between Prefrail and Frail Older Women: A Systematic Review.

The current review aimed to explore similarities and differences in the properties of interventions that promote physical and psychological health between prefrail and frail older women. Ten databases were searched for studies published from database inception to May 2023. Two Cochrane tools were used to assess the risk of bias in experimental and quasi-experimental studies. Twenty-three studies were selected, including 11 studies on prefrailty and 12 studies on frailty. Exercise interventions were predominant, but the contents and standards of exercise intensity were inconsistent between prefrail and frail women. For the main outcomes of the interventions, balance ability and biochemical factors were measured more frequently for frail older women than prefrail older women. Psychological health was less measured for prefrail and frail older women compared to physical health. Future research needs to consider balance training, as well as the evaluation of biochemical factors and psychological health among prefrail or frail older women. [Journal of Gerontological Nursing, 49(10), 20-28.].

A Clinical Data Warehouse Analysis of Risk Factors for Inpatient Falls in a Tertiary Hospital: A Case-Control Study.

OBJECTIVES: The aims of the study are to identify fall risk factors and to establish automatic risk assessments based on clinical data from electronic medical records of hospitalized patients. METHODS: In this retrospective case-control study, we reviewed the electronic medical records of 1454 patients (292 and 1162 patients in the fall and nonfall groups, respectively) who were hospitalized at a 1800-bed tertiary hospital in South Korea between January 1, 2017, and December 31, 2017. Patients' age, sex, and clinical department were matched, and all laboratory reports, clinical flow sheets, and nursing initial assessment records of case from the Clinical Data Warehouse system were analyzed. The collated patient records data were analyzed using SAS (version 9.4) and logistic regression. RESULTS: Overall, 65 risk factors, including low body mass index, low blood pressure, low albumin levels, high fasting blood sugar level, low red blood cell counts, and high potassium levels, that significantly increased the incidence of falls were identified. Falls were also associated with 21 items from the clinical flow sheet and nursing initial assessment, including frequent bowel movements, 24-hour urine tests, imaging tests, biopsy, pain, intravenous tubes, unclear consciousness, and taking medication. CONCLUSIONS: Fall risk factors identified via the Clinical Data Warehouse can be used to build an automated detection system to detect fall risk in electronic medical records, enabling nurses to assess the fall risk in addition to using the fall scale.

Mycorrhizal Fungal Diversity Associated with Six Understudied Ectomycorrhizal Trees in the Republic of Korea.

Mycorrhizal fungi are key components of forest ecosystems and play essential roles in host health. The host specificity of mycorrhizal fungi is variable and the mycorrhizal fungi composition for the dominant tree species is largely known but remains unknown for the less common tree species. In this study, we collected soil samples from the roots of six understudied ectomycorrhizal tree species from a preserved natural park in the Republic of Korea over four seasons to investigate the host specificity of mycorrhizal fungi in multiple tree species, considering the abiotic factors. We evaluated the mycorrhizal fungal composition in each tree species using a metabarcoding approach. Our results revealed that each host tree species harbored unique mycorrhizal communities, despite close localization. Most mycorrhizal taxa belonged to ectomycorrhizal fungi, but a small proportion of ericoid mycorrhizal fungi and arbuscular mycorrhizal fungi were also detected. While common mycorrhizal fungi were shared between the plant species at the genus or higher taxonomic level, we found high host specificity at the species/OTU (operational taxonomic unit) level. Moreover, the effects of the seasons and soil properties on the mycorrhizal communities differed by tree species. Our results indicate that mycorrhizal fungi feature host-specificity at lower taxonomic levels.

Potential of a bivalent vaccine for broad protection against enterovirus 71 and coxsackie virus 16 infections causing hand, foot, and mouth disease.

Hand, foot, and mouth disease (HFMD) is a highly contagious viral infection that is mainly caused by enterovirus 71 (EV71) and coxsackievirus 16 (CVA16). As there are no specific therapeutics for HFMD, the development of a bivalent vaccine is required to cover a broad range of infections. In this study, the effectiveness of novel monovalent and bivalent vaccines targeting EV71 C4a and CVA16 was investigated for their ability to prevent viral infections in neonatal human scavenger receptor class B member 2 (hSCARB2) transgenic mice. As hSCARB2 serves as a key viral receptor for EV71, these transgenic mice are susceptible to EV71 strains and facilitate viral binding, internalization, and uncoating processes. Antisera prepared by vaccine immunization were transferred to 2-day-old hSCARB2 transgenic mice, which were then infected with EV71 C4a or CVA16 virus. The antisera generated by each monovalent or bivalent vaccine effectively protected against EV71 C4a and CVA16 infections. The examination of tissue damage and viral contents in various organs indicated that both monovalent and bivalent antisera reduced EV71 C4a viral load in the brainstem, and no significant tissue damage was observed. During CVA16 infection, the monovalent and bivalent antisera significantly reduced viral contents in both the brainstem and muscles. These results suggest that passive immunity by monovalent and bivalent antisera can effectively protect against EV71 C4a and CVA16 infections. Thus, the development of a bivalent vaccine that can provide broad protection against both CV and EV infections may be a promising strategy in preventing HFMD.

Association Between Social Frailty and Life Satisfaction Among Older Adults: The Role of Functional Limitations and Depressive Symptoms.

The current study aimed to identify life satisfaction depending on the degree of social frailty and explore the mediating role of functional limitations and depressive symptoms between social frailty and life satisfaction. A secondary analysis of a cross-sectional survey was used. Data of 6,479 older adults were selected from the 2020 National Survey of Older Koreans. Of all participants, 2,595 (40.1%) and 1,605 (24.8%) had social prefrailty and frailty, respectively. Life satisfaction of participants with social frailty was significantly worse than those without social frailty. Social frailty negatively influenced life satisfaction. Functional limitations and depressive symptoms serially mediated the association between social frailty and life satisfaction. This mediation model provided evidence of the associations among social frailty, functional limitations, depressive symptoms, and life satisfaction in older adults. In community care settings, nurses should recognize the assessment of social frailty to enhance the subjective well-being of older adults. [Research in Gerontological Nursing, 16(6), 291-300.].

Correlation of health-related quality of life for older adults with diabetes mellitus in South Korea: theoretical approach.

BACKGROUND: While some studies have explored the health-related quality of life (HRQOL) of older adults with diabetes mellitus (DM) in South Korea using a theoretical framework, these studies suffer sample-related limitations, as they focus only on a specific subgroup of older adults. To address this gap, this study aimed to investigate the predictors of HRQOL of older adults with DM in South Korea, using extensive national data and based on the theory of Health-Related Quality of Life in South Korean Older Adults with Type 2 Diabetes (The HIKOD theory). METHODS: A secondary data analysis was conducted using data from 1,593 participants aged 65 years and older with DM sourced from the 2015-2019 Korea National Health and Nutrition Examination Survey (KNHANES). The variables included in this study are as follows: demographic factors (gender, age, household income, and education level), disease-specific factors (duration of DM, treatment of DM, and control of HbA1c), barriers (number of comorbidities), resources (living alone status), psychosocial factors (perceived stress), and health-promoting behaviors (physical activity and fundus examination). Considering the complex sampling design employed in this study, statistical analyses including Rao-Scott chi-square tests, correlation analysis, and hierarchical multiple regression analysis were conducted. RESULTS: Mobility (45.0%) was the HRQOL dimension with which participants experienced the highest number of problems. Number of comorbidities (r = -0.36, p < 0.001), living alone status (rpb = 0.16, p < 0.001), perceived stress (rpb = 0.14, p < 0.001), and physical activity (rpb = 0.12, p < 0.001) were correlated with HRQOL. While adjusting for background factors, HRQOL was negatively predicted by higher number of comorbidities (estimate B = -0.03, p < 0.001), living alone (estimate B = -0.03, p = 0.043), higher perceived stress (estimate B = -0.09, p < 0.001), and lower physical activity (estimate B = -0.03, p < 0.001). CONCLUSION: Complex and diverse factors influence HRQOL among older adults with DM in South Korea. To improve their HRQOL, intervention programs that integrally regard HRQOL, along with various predictors, are necessary.

Health education interventions for individuals with hearing impairment: A systematic review.

OBJECTIVES: This study aims to systematically review health education interventions targeting individuals with hearing impairment. METHODS: A total of 18 studies were selected based on search results from five databases, and quality appraisal was conducted using an appropriate tool based on the study design. The extracted results were described using qualitative analysis. RESULTS: Among the selected studies, most interventions focused on specific cancers, and video materials were the most common delivery method. Various strategies were applied depending on the type of materials provided, in addition to sign language interpretation and the involvement of hearing-impaired related personnel. The interventions primarily resulted in a significant increase in knowledge. CONCLUSION: This study suggests several recommendations, including expanding the scope of interventions to cover various chronic diseases, actively utilizing the features of video materials, considering health literacy, using peer support groups, and measuring behavior-related factors alongside knowledge levels. PRACTICE IMPLICATIONS: This study makes a significant contribution to understanding the unique characteristics of the population with hearing impairment. Furthermore, it has the potential to facilitate the development of high-quality health education interventions for individuals with hearing impairment by providing insights into future research directions based on existing health education interventions.

Development of nutrigenomic based precision management model for Hanwoo steers.

Focusing high marble deposition, Hanwoo feedlot system uses high-energy diet over the prolonged fattening period. However, due to the individual genetic variation, around 40% of them are graded into inferior quality grades (QG), despite they utilized the same resources. Therefore, focusing on development of a nutrigenomic based precision management model, this study was to evaluated the response to the divergent selection on genetic merit for marbling score (MS), under different dietary total digestible nutrient (TDN) levels. Total of 111 calves were genotyped and initially grouped according to estimated breeding value (high and low) for marbling score (MS-EBV). Subsequently, managed under two levels of feed TDN%, over the calf period, early, middle, and final fattening periods following 2 × 2 factorial arrangement. Carcasses were evaluated for MS, Back fat thickness (BFT) and Korean beef quality grading standard. As the direct response to the selection was significant, the results confirmed the importance of initial genetic grouping of Hanwoo steers for MS-EBV. However, dietary TDN level did not show an effect (p > 0.05) on the MS. Furthermore, no genetic-by-nutrition interaction for MS (p > 0.05) was also observed. The present results showed no correlation response on BFT (p > 0.05), which indicates that the selection based on MS-EBV can be used to enhance the MS without undesirable effect on BFT. Ultimate turnover of the Hanwoo feedlot operation is primarily determined by the QGs. The present model shows that the initial grouping for MS-EBV increased the proportion of carcasses graded for higher QGs (QG1++ and QG1+) by approximately 20%. Moreover, there appear to be a potential to increase the proportion of QG 1++ animals among the high-genetic group by further increasing the dietary energy content. Overall, this precision management strategy suggests the importance of adopting an MS based initial genetic grouping system for Hanwoo steers with a subsequent divergent management based on dietary energy level.

Benefits and harms of normal saline instillation before endotracheal suctioning in mechanically ventilated adult patients in intensive care units: A systematic literature review and meta-analysis.

OBJECTIVES: This systematic review aimed to identify the effects of normal saline instillation before endotracheal suctioning on clinical outcomes in critically ill patients on a mechanical ventilator. RESEARCH METHODOLOGY: This review was based on the guidelines of the National Evidence-based Healthcare Collaborating Agency in Korea and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Six electronic databases were searched for relevant literature. Other sources were also searched, including the reference lists of identified reports and previous systematic reviews. After the initial literature search, a two-step retrieval process was performed to select eligible studies. Then, data were collected using a newly developed form, and the risk of bias was assessed using the checklists of the Joanna Briggs Institute. Data were analyzed using both narrative syntheses and meta-analyses. RESULTS: In total, 16 studies: 13 randomized controlled trials and three quasi-experimental studies, were included. From the narrative syntheses, instilling normal saline before endotracheal suctioning was associated with a decrease in oxygen saturation, prolonged time for oxygen saturation to recover to baseline, decreased arterial pH, increased secretion amount, reduced incidence of ventilator-associated pneumonia, increased heart rate, and increased systolic blood pressure. Meta-analyses showed a significant difference in heart rate at five minutes after suctioning but no significant differences in oxygen saturation at two and five minutes after suctioning and heart rate at two minutes after suctioning. CONCLUSION: This systematic review indicated that instilling normal saline before performing endotracheal suctioning has more harmful effects than benefits. IMPLICATIONS FOR CLINICAL PRACTICE: As recommended in the current guidelines, it is necessary to refrain from routine normal saline instillation before endotracheal suctioning.