The goal of this quasi-experimental clinical trial is to learn if position management combined with the Active Cycle of Breathing Techniques (ACBT) works to reduce postoperative pulmonary complications in adult patients undergoing elective cardiac surgery. It will also evaluate the individual effects of each technique compared to routine care.

The main questions it aims to answer are:

Does the combination of positioning and ACBT significantly lower the incidence and severity of postoperative pulmonary complications (like atelectasis, pneumonia, and respiratory failure) within the first 7 days after surgery? Does the combination of these techniques reduce the length of hospital stay compared to using each technique alone or routine care? Does the application of ACBT alone lower the rate of respiratory infections? Does position management alone improve oxygenation parameters (such as SpO_{2} and PaO_{2})?

Researchers will compare four groups of patients to determine the most effective nursing approach:

Group 1 (Control Group): Participants will receive routine postoperative hospital care only.

Group 2 (ACBT Group): Participants will perform the Active Cycle of Breathing Techniques (breathing control, thoracic expansion, and huffing) three times daily for 10-15 minutes over 5 postoperative days.

Group 3 (Positioning Group): Participants will receive structured position management exclusively, shifting from head elevation (30-45) early after surgery to a semi-recumbent position (approx60) during waking hours, alongside other positions like lateral or forward-leaning as tolerated.

Group 4 (Combined Group): Participants will receive both structured position management and perform the ACBT sessions according to the same schedules.

All participants will undergo daily respiratory assessments using a standardized scoring system for 7 days post-surgery or until hospital discharge.

This quasi-experimental, non-equivalent control group study is designed to evaluate the clinical impact of position management, the Active Cycle of Breathing Techniques (ACBT), and their combined application on reducing postoperative pulmonary complications (PPCs) among adult patients undergoing elective cardiac surgery via median sternotomy.

Study Phases and Flow:

1. Preparatory Phase: Official administrative approvals will be secured from the director of the cardiothoracic care unit (CTCU) at Assiut University Heart Hospital. The data collection tools will be validated by a jury panel of five experts in medical-surgical nursing and cardiothoracic surgery.

Internal consistency will be evaluated using Cronbach's Alpha. A pilot study involving 10% of the sample size (13 patients) will be conducted to test feasibility and timing, and these patients will be excluded from the final analysis.

Eligible patients will be approached preoperatively to explain the study's purpose, benefits, and risks, and voluntary written informed consent will be obtained.

Implementation Phase:

Patients meeting the specific eligibility criteria will be enrolled. Preoperatively, baseline demographic attributes, clinical medical history, initial diagnostic studies (e.g., complete blood count, chest X-ray, arterial blood gas markers), and baseline vital signs will be documented. Patients allocated to the intervention arms will receive preoperative training on ACBT maneuvers and orientation regarding the postoperative position protocols.

During and immediately following surgery, operative variables such as extracorporeal circulation time, aortic cross-clamp time, and intraoperative blood transfusions will be extracted from anesthesia and surgical flow sheets. Patients will then be allocated into one of the four study groups. Group Interventions:

• Group 1 (Control Group): Participants receive only the standard, routine postoperative hospital care protocols.
• Group 2 (ACBT Group): Once hemodynamically stable on postoperative day 1 (POD 1), participants perform the active cycle of breathing technique (including breathing control, thoracic expansion exercises, and huffing). Sessions last 10-15 minutes, conducted three times daily across 5 postoperative days.
• Group 3 (Positioning Group): In the early postoperative phase (0-6 hours or until extubation), patients are managed with head elevation at $30-45^{\circ}$ and head turning. Post-extubation/after 6 hours, they are maintained in a semi-recumbent position (approx60) during waking hours and 15-30 during sleep, with forward-leaning, postural drainage, and prone positioning integrated as tolerated.
• Group 4 (Combined Group): Participants receive the structured early head elevation and semi-recumbent positioning, followed by lateral or forward-leaning adjustments. Following extubation and stabilization, they initiate the ACBT sessions on the identical frequency and duration schedule as Group 2. Evaluation Phase:

Continuous daily monitoring of vital signs and clinical progress will be documented from POD 1 to POD 7. The incidence and clinical severity of PPCs will be evaluated daily using the Modified Kroenke Scoring System. Data collection will conclude on POD 7 or upon hospital discharge, whichever occurs first. Statistical analysis will compare the variations across the four groups to identify the most effective nursing practice.

Inclusion Criteria:

• Adult patients (aged from 20 years to 65 years old).
• Undergoing elective cardiac surgery (Coronary Artery bypass Grafting (CABG) or valves surgeries) via median sternotomy.
• Hemodynamically stable postoperatively (no high-dose vasopressor support).
• Fully conscious and capable of following complex verbal instructions.

Exclusion Criteria:

• • Patients undergoing emergency cardiac surgery.

  • History of chronic respiratory diseases such as chronic obstructive pulmonary disease (COPD), bronchial asthma, or bronchiectasis
  • Pre-existing pulmonary complications (e.g., pneumonia, atelectasis, pleural effusion) prior to surgery
  • Neuromuscular disorders affecting respiratory muscles
  • Severe obesity (e.g., BMI ≥35 kg/m²)
  • Cognitive impairment or inability to follow instructions
  • Any contraindication to physiotherapy techniques (e.g., unstable sternum, severe pain not controlled)

To protect patient confidentiality and ensure strict adherence to the ethical guidelines and informed consent approved by the Institutional Review Board (IRB), the individual participant data collected during this study will not be made publicly available. Only aggregated statistical results will be published in the final dissertation and related journal manuscripts.