Introduction
Acute heart failure (AHF) is a growing global public health concern affecting approximately 64 million people. Its prevalence is increasing due to aging populations, improved survival after myocardial infarction, and advances in evidence-based therapies. Despite progress, AHF remains associated with high mortality, reduced functional capacity, and substantial healthcare costs [1].
AHF is a clinical syndrome characterized by typical symptoms (e.g. dyspnea, ankle swelling, and fatigue) that may be accompanied by signs (e.g. elevated jugular venous pressure, pulmonary crackles, and peripheral edema). Many patients progress to dyspnea at rest, including at night [2]. 
Management of AHF includes diuretics, vasodilators, and cardiac glycosides. According to the American Heart Association (AHA), positioning and light physical exercises may reduce respiratory effort, enhance respiratory muscle function, and improve tissue perfusion and circulation [3]. Breathing exercises are the most common form of non-assisted respiratory training. Deep breathing and active range of motion (ROM) improve respiratory muscle strength, circulation, and help reduce dyspnea in patients with AHF [4].
Nurses play a key role in AHF care, particularly in respiratory assessment, oxygen therapy, fluid balance, and medication management. International guidelines (AHA, ESC) emphasize early assessment, symptom control, patient education, and multidisciplinary collaboration [5, 6]. Evidence-based nursing interventions improve AHF outcomes by ensuring continuous monitoring, fluid management, and support for adherence [7].
AHF is a significant cause of hospitalization, often accompanied by respiratory distress from pulmonary congestion and impaired gas exchange. Respiratory complications increase morbidity and length of stay. Studies [8, 9] have shown that structured nursing guidelines targeting respiratory care can improve outcomes. To address this gap, the current study evaluates the impact of standardized nursing guidelines on respiratory status among patients with AHF, providing evidence for more effective nursing care.



Methods
Study design
A quasi-experimental research design was utilized in this study. Patients were randomly assigned to the intervention and control groups using a computer-generated randomization table in Excel 2016. Due to the nature of the nursing intervention, blinding of patients was not feasible. However, outcome assessors were blinded to group allocation because they collected data solely from coded electronic and written medical records without any group identifiers. This approach was used to minimize assessment bias.

Hypothesis
H1: Patients in the intervention group will show a statistically significant improvement in respiratory status compared to the control group. H2: Patients in the intervention group will show a decrease in complications, length of stay, and mortality compared to the control group 
Time and place of study
Data collection was conducted from August 2023 to September 2024, approximately, with a convenient sample of about 100 patients. The data were collected from the emergency department (ED) and the CCU in Assiut Heart Hospital, Egypt.

Data collection 
The researcher introduced herself to patients and nursing staff, obtained patients’ verbal consent, and explained the study’s purpose. Data were collected from patients with AHF in the specified setting over a five-day period, who met the criteria of being aged >18 years, newly admitted patients with AHF, and male and female patients. Patients with comorbid chronic obstructive pulmonary disease (COPD), unconsciousness, pregnancy, or stroke were excluded. Strict inclusion and exclusion criteria were applied. Comorbidities, medication adherence, and heart failure severity (based on New York Heart Association [NYHA] classification) were considered in the analysis. Although socio-economic status was not assessed, its potential impact is acknowledged as a study limitation.

Sample size
A purposive sample of adult patients of both sexes admitted with AHF was selected. Based on the primary outcome (length of hospital stay), the minimum required sample size was 84 participants. To account for potential dropout, the sample was increased to 100 patients (50 per group). The sample size was calculated using G*Power software, version 3.1.9.2, assuming a large effect size (>0.8), with hospital stay estimated at 4.73±0.93 days in the intervention group and 10.11±1.83 in the control group [10] based on previous research. A two-tailed t-test was used for group comparisons. Alpha=0.05, Power=0.95, Effect size=0.8 and Allocation ratio=1

Data collection tools 
Three tools were used in this study:
I. Patient assessment tool: The patient assessment tool was designed to determine patients’ personal characteristics and consisted of two parts: 
Part 1: Demographic data, including the patient’s code, gender, and age. Part 2: Arterial blood gases (ABG), including  PH, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaO2), bicarbonate (HCO3), and SaO2, arterial O2 saturation (SaO2).
II. Respiratory assessment tool: The respiratory assessment tool was used to assess the respiratory status of the patients [11] and consisted of two parts: 
Part 1: Chest examination includes respiratory rate, accessory muscle use, and chest sound assessment. Part 2: Assessment dyspnea scale (position-based rating scale [PRS]) was used to measure dyspnea severity determined by patients self-reporting. This validated tool was adopted from Zhang et al. [12] and consisted of five items: absence of dyspnea at rest (0 points), dyspnea in the supine position (1 point), paroxysmal nocturnal dyspnea (2 points), dyspnea in the semi reclining position (3 points), and orthopnea (4 points), which calculated 10 points.
III. Patientsꞌ outcomes tool: Patientsꞌ outcomes tool was used to evaluate patientsꞌ outcomes and consisted of three parts: 
Part 1: Complications included chest infection, arrhythmia, digitalis toxicity, hypokalemia, hyperkalemia, and hyponatremia. Part 2: Length of stay in the coronary care unit (CCU), ED, and hospital. Part 3: Mortality, number of patients transferred to the ward, and  number of patients discharged to home in both groups [13, 14]. The study was conducted in three stages.

Preparatory stage
Permission to conduct the study was obtained from the hospital’s responsible authorities after an explanation of the aim of the study.

Content validity
The developed tools (I, II part 1, III) were tested for content-related validity by five experts in the field of critical care and emergency nursing and cardiovascular department at Assiut University, and necessary modifications were made. 

Pilot study
A pilot study was conducted on 10% of the sample (10 patients) to assess the feasibility, safety, and preliminary effectiveness of the intervention, following approval from hospital administration.

The reliability
The reliability was assessed on the tools using Cronbach’s α to assess the consistency and stability of the tools as follows:
“Tool I patient assessment tool: 0.835”; “Tool II respiratory assessment Tool Part 1: 0.850”; “Tool III: 822”

Implementation stage
Both groups
Both groups were assessed for:
Baseline data (age and gender) were collected through patient interviews using Tool I, Part 1. ABG values and chest assessments (chest examination and sounds) were extracted from electronic medical records at admission, day 3, and day 5 using Tool I, Parts 1 and 2. Dyspnea severity was assessed through direct patient interviews and clinical observation using Tool II, Part 2.

Control group
The control group received the routine hospital care in the CCU and the ED. 

Intervention group
The intervention group received the AHF nursing guideline as follows:
The AHF nursing guideline was applied by the researcher with assistance from critical care nurses involved in patient care and exercise implementation.
A 2-hour orientation session was provided to the nurses, followed by a competency checklist and observational assessment. A dedicated team of trained critical care nurses was assigned to this group. Nurses adhered to the guidelines under regular supervision to ensure compliance and correct performance. The intervention was delivered twice daily, each session lasting 30 minutes.

Part 1: Respiratory support through
Nurses played a vital role in managing patients requiring respiratory support, including continuous monitoring of respiratory patterns, administering oxygen when SpO₂ <90%, and initiating non-invasive ventilation when clinically indicated. Proper positioning (e.g. high-Fowler’s position) was maintained to improve oxygenation.
Serum electrolytes, particularly sodium and potassium, were routinely monitored; baseline values were obtained before the intervention, with follow-up tests conducted to identify imbalances. Nurses also supported medication administration, monitored responses, reported adverse effects, and reinforced adherence.
Patients were encouraged to perform deep breathing and coughing exercises for 15 minutes, twice daily, to reduce dyspnea and prevent respiratory complications (e.g. atelectasis) [15]. 
Part 2: Warm-up activities and active range of motion (AROM)
Warm-up and AROM exercises were individualized and low-intensity, designed to remain within safe exertion limits to avoid cardiovascular strain. Each session began with 5–10 minutes of warm-up activities to prepare patients for exercise [16]. These included:
Arm circles and shoulder rolls: Performed in a standing or seated position by extending arms and making small circles for 30 seconds in each direction, followed by shoulder rolls forward and backward (30 seconds each). Purpose: To loosen shoulder joints and enhance blood flow.
Ankle and wrist rotations: While seated, participants rotated ankles and wrists in circular motions for 30 seconds each. Purpose: To reduce joint stiffness and enhance mobility. Deep breathing with gentle stretching: Involved slow inhalation through the nose while raising the arms, followed by exhalation while lowering them.
Heel-toe taps: Performed while seated or standing, alternately tapping the heel then toe of each foot for 1–2 minutes. Purpose: To improve circulation in the lower limbs. Neck and side stretching: Included gentle tilting of the head side to side and overhead arm stretches with side bending. Purpose: To relieve upper-body tension.

AROM
The exercises were divided into two stages based on the patient’s position: supine (lying down) and sitting upright in bed or on a chair. In the supine position, the routine included:
1) arm elevation above the head and return to the side position; 2) bilateral leg flexion and extension
3) Arm abduction; 4) heel sliding forward and backward to stimulate lower limb circulation. In the sitting position, the patient performed:
5) forward trunk flexion and return to upright posture; 6) Alternating knee lifts; 7) arm swings forward and backward to promote coordination and chest expansion Vazquez et al. [17]

Part 3: Acute phase and early ambulation program 
After weaning from oxygen and resolution of the acute phase, an early ambulation program was initiated. This was followed by patient preparation, assessment of background and exacerbation factors, evaluation of cardiac function and hemodynamics.
Acute phase early ambulation program adopted from Izawa et al. [18] and used by Makita et al. [19]. The acute phase ambulation program consists of six progressive stages based on patient recovery and tolerance:
Stage 1: Complete bed rest; rehabilitation conducted in bed. Stage 2: Sitting upright in the room; bedside rehabilitation; approximately one hour of sitting. Stage 3: Walking up to 40 meters and free movement within the room; bedside rehab; approximately two hours of sitting. Stage 4: Walking up to 80 meters; rehabilitation in the ward; approximately three hours of sitting. Stage 5: Same as Stage 4; continued ward-based rehabilitation. Stage 6: Free ambulation within the ward, including walking 80 meters two to three times daily; rehabilitation in the rehab room; approximately three hours of sitting.

Part 4: 6-minute walk test adopted from Marinho et al. [20]. 
After the early ambulation program, the six-minute walk test was performed.
Stopwatch; Measuring/trundle wheel to measure distance covered; 30-meter stretch of unimpeded walkway; two cones to mark the distance that needs to be covered; pulse oximeter for measuring heart rate and SpO2 (optional); terminate exercise if warning signs or symptoms occur, including dizziness, arrhythmias; unusual shortness of breath, or angina and discomfort.

Evaluation stage
All patients with AHF were evaluated within five days and until discharge for complications, length of stay, and mortality using electronic and written medical records, including discharge summaries. Chest infections were assessed via sputum culture reports from electronic records.

Statistical analysis
Data entry and analysis were performed using SPSS software, version 22. Data were presented as numbers, percentages, Mean±SD, medians, and interquartile ranges (IQR). The chi-square and Fisher’s exact tests were used to compare qualitative variables. The normality of the quantitative variables was tested with the Shapiro-Wilk test. In case of parametric data, an independent sample t-test was used to compare quantitative variables between groups, and a Mann-Whitney test was used for non-parametric data. Repeated measures analysis of variance (ANOVA) for within-group comparison in each group. Multiple logistic regression was performed to identify risk factors. P considered statistically significant when P<0.05.

Results
Table 1 presents that most of the patients were male. Significant differences in age were observed between groups. Also, it presents that the intervention group had significantly better SaO2 in the third and fifth days, and these findings confirm Hypothesis 1.  
Table 2 presents that the intervention group had significantly less accessory muscle use, improved chest sounds, and lower dyspnea on the fifth day. The statistical significance of these findings confirms Hypothesis 1.
Table 3 presents that the intervention group had lower mortality (10%), fewer chest infections, and shorter hospital stays. Multiple logistic regressions revealed no significant association between age, gender, SaO2 and mortality (P>0.05). Although males had higher mortality odds, gender was not a significant predictor (odd ratio [OR]=1.683; 95% confidence interval [CI], 0.515%, 5.501%; P=0.389).



Abbreviations: PaO2: Partial pressure of oxygen; PaCO2: Partial pressure of carbon dioxide; HCO3: Bicarbonate; SaO2: Arterial O2 saturation; P2: Statistical significance of changes over time within each group independently.
aIndependent samples t-test, bchi-square test , crepeated measures ANOVA, *statistically significant difference (P<0.05)











Discussion
AHF is a growing global health problem, affecting millions annually and associated with high morbidity and mortality. Despite advances in evidence-based pharmacological and device therapies, its overall prognosis remains poor [21].
The present study showed that the mean age of patients was 55.76±10.51 in the control group, while the intervention group had a slightly lower mean age of 50.88±12.18. Regarding patients’ gender, the control group had a slightly higher proportion of females than males. In contrast, the intervention group had a significantly higher proportion of males compared to females. These factors are often associated with cardiovascular health risks. 
This finding was supported in Egypt by Hussein et al. [22], who found that the highest percentage of both groups of patients with AHF whose ages ranged between 40<60 years were male. This was inconsistent with Carmin et al. [23], who found that the majority of patients with AHF were women.
Regarding ABG, a statistically significant difference in SaO2 levels was observed, indicating better oxygen saturation in the intervention group on days 3 and 5. This suggests the positive effect of deep breathing exercises and an ambulation program on AHF patients. Other ABG parameters (pH, PaO2, PaCO2, HCO3) showed no significant differences between groups.
These findings were consistent with Radaelli et al. [24], who found that slowing respiratory rate reduces dyspnea and improves both resting pulmonary gas exchange and exercise performance in patients with AHF, and improves oxygen saturation. These findings were inconsistent with Kagami et al. [25], who found that during exercise, heart rate and systolic blood pressure were lower in the patients with AHF than those in controls, while the oxygen saturation was similar between the groups.
The intervention group showed significant improvement in respiratory function, evidenced by reduced accessory muscle use on days 3 and 5, suggesting that deep breathing and active ROM enhanced recovery.
These results were consistent with Piotrowska et al. [26], who showed that significant statistical improvement was observed in the majority of the hemodynamic parameters, lung function parameters, and respiratory muscle strength in the exercise-based cardiac rehabilitation and inspiratory muscle training in AHF patients. These results were inconsistent with Greene et al. [27], who reported that nurse-led protocols (e.g. early mobilization, self-care education) did not reduce readmission rates or mortality in AHF patients.
At admission, both groups had similar chest-sound distributions, mostly crepitation. By days 3 and 5, the intervention group showed significant improvement, with reduced crepitation and abnormal sounds, indicating the effectiveness of the nursing guideline. These results were consistent with Gunawan et al. [28], who found that nursing care for patients with AHF is well managed. Providing deep-breathing relaxation interventions is effective in reducing respiratory rate.
The intervention group had a lower median dyspnea score compared to the control group on the fourth and  fifth days. This suggests that deep breathing exercise improved patient’s dyspnea, which reduced the dyspnea score. This result is supported by Neşe and Bağlama  [29], who found that deep breathing exercises were effective in decreasing their dyspnea and fatigue symptoms in patients. However, these results are not in line with those of Kittleson et al. [30], who found that AHF patients with structured deep breathing exercises did not improve dyspnea scores or oxygen saturation compared to standard care.
The intervention group showed improved respiratory status, including higher SaO2, reduced accessory muscle use, and progressive chest sound clearance, lower rates of crepitation, and improved patient dyspnea. Based on these results, Hypothesis 1, “Patients in the intervention group will show a statistically significant improvement in respiratory status compared to the control group,” was supported.
The current study revealed that the nursing guidelines for AHF had a positive effect on mortality rate, discharge to home and transfer to ward. These results are consistent with Son et al. [31], who found that nurse-led heart failure self-care education significantly reduced the risk of all-cause readmission and all-cause mortality.
The current study found that chest infection showed a statistically significant reduction in the intervention group. This suggests that applying nursing guidelines and closely monitoring to patients with AHF had a positive effect on patients’ outcomes. 
This result was consistent with the study by Geng et al. [32], who mentioned that various types of nursing guidelines can effectively influence the improvement of patients with AHF and decrease the complications rate. This was inconsistent with Abel et al. [33], who reported that reduced chest infection rates in intervention groups were more strongly associated with hospital-wide infection control protocols (e.g. hand hygiene, ventilator management) than nursing guidelines. 
A statistically significant reduction in hospital stay was observed in the intervention group, suggesting that nursing guidelines positively impacted length of stay and mortality in patients with AHF. This finding was consistent with that of Beghini et al. [34], who reported that early interventions and optimized medication reduce hospitalizations. However, it was inconsistent with Peschanski et al. [35], who found no reduction in hospital stay among patients with AHF receiving early mobilization.
Statistically significant differences were found between groups in age, gender, and SaO2; however, multiple logistic regression showed none were independently associated with mortality. Male gender and lower SaO2 trended toward higher mortality, but without statistical significance. These findings were consistent with De Matteis et al. [36], who reported few independent predictors of in-hospital mortality. Conversely, Wu et al. [37] found a higher risk of all-cause death in male patients with AHF. As expected, a worse NYHA class was strongly associated with increased mortality, particularly with advancing age.
The nursing guidelines improved key outcomes in patients with AHF, including dyspnea, respiratory function, chest sound clearance, hospital stay, and mortality. Its application in ED and CCU settings may enhance respiratory status. Deep-breathing exercises were particularly practical. Close nursing monitoring and guideline adherence are essential to reduce complications, mortality, and hospitalization duration.

Conclusion
Nursing guidelines among patients with AHF have been successful in improving respiratory status and decreasing complications, length of stay, and mortality.

Recommendations
Apply AHF nursing guidelines in ED and CCU to improve respiratory status. Provide educational materials for nurses in both units. Replicate the study with larger, geographically diverse samples in Egypt.

Study limitations 
A small, convenience-based sample with limited geographic diversity limited this study. Socio-economic status was not assessed, which may have influenced outcomes. Although the intervention was associated with improved respiratory outcomes and reduced mortality, further studies in diverse settings are required. Although baseline differences in age, gender, and SaO2 existed, these variables were independently linked to mortality, suggesting the effect was likely due to the intervention rather than confounders.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of Assuit University, Asyut, Egypt (Code: 1120220526).Written informed consent was obtained from patients who were willing to participate in the study, after explaining the nature and the purpose of the study. Patient privacy was considered during the data collection. Each patient had the right to refuse participation or withdraw from the study at any time without providing a reason. 

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
All authors contributed equally to the conception and design of the study, data collection and analysis, interpretation of the results, and drafting of the manuscript. Each author approved the final version of the manuscript for submission.

Conflict of interest
The authors declared no conflicts of interest.

Acknowledgments
The authors express their gratitude to all those who played a role in implementing this research and facilitating its progress.

References