Postoperative Diaphragm Function in Pediatric Laparoscopic Abdominal Surgery Using Compliance and PEEP Guided by Lung Ultrasound

Experimental studies have proven a relationship between inappropriate ventilation measures and delayed or even worsened recovery from acute pulmonary injury. Therefore, the importance of protective ventilation combined with recruitment maneuvers emerges. In clinical practice, this relationship is believed to significantly reduce morbidity, mortality, and injuries caused by mechanical ventilation.

It is indicated in patients with severe hypoxemia, often due to acute lung injury caused by pneumonia or sepsis. The main contraindications are hemodynamic instability, pneumothorax, and intracranial hypertension. Experimental studies have shown that lung-protective ventilation has beneficial effects on both oxygenation and alveolar collapse. In children, lung-protective ventilation leads to significant reductions in alveolar collapse, lower oxygen requirements, improved pulmonary compliance, and decreased bronchopulmonary dysplasia. However, studies conducted on children are limited.

Recent changes have been made regarding how children with acute hypoxemic respiratory failure are ventilated. Lachmann proposed the "open lung concept," which involves opening the lungs and keeping them open during mechanical ventilation. ARM has been used for over two decades in mechanically ventilated patients with severe lung injury. Its most significant physiological outcome is the improvement in oxygenation in patients with lung damage. The procedure is typically followed by adjustments in PEEP levels, which play a fundamental role in maintaining the effectiveness of ARM. ARM is also used to prevent alveolar collapse during low tidal volume mechanical ventilation. However, its primary purpose is to protect the lungs from ventilator-induced injuries. PEEP has a key role in preventing atelectrauma and maintaining the maneuver's effectiveness. In clinical practice, these strategies are believed to significantly reduce morbidity and mortality.

In this study, it is aimed to define the limits of "diaphragm-protective ventilation" based on the clinical outcomes of our patients by evaluating the effects of different PEEP levels adjusted during laparoscopic abdominal surgery in pediatric patients. Additionally, it will be seeked to assess the impact of positive end-expiratory pressure levels on diaphragm thickness.

Our primary hypothesis is that, in patients where ideal PEEP is applied based on dynamic compliance measured with ultrasound (USG), diaphragm values will return closer to baseline values compared to those where recruitment maneuvers and ideal PEEP are applied.

Secondly, it is aimed to investigate the effects of calculating ideal PEEP using dynamic compliance measured with USG on hospital length of stay, intraoperative hemodynamic parameters, and respiratory parameters.

Inclusion criteria

• Participants meeting the following criteria will be included in the study:
• Aged 7 to 12 years
• ASA classification I, II, or III
• Undergoing elective laparoscopic abdominal surgery

Exclusion criteria

Participants with any of the following conditions will be excluded from the study:

• Age <7 or >12 years
• ASA classification > III
• Uncontrolled bronchial asthma
• Presence of bullous lung disease
• Decompensated heart failure (NYHA Stage III-IV)
• History of lung surgery
• Increased intracranial or intraocular pressure
• Advanced hepatic or renal failure
• Parental refusal to participate in the study