Respiratory management of pediatric patient with bronchiolitis obliterans syndrome during general anesthesia surgery: a case report

Introduction

Bronchiolitis obliterans syndrome (BOS) is a progressive lung disease that can occur after allogeneic hematopoietic stem cell transplantation (HSCT), particularly in patients with chronic graft-versus-host disease (cGVHD), with an incidence of 4.5% to 8.3% (1). It is characterized by excessive proliferation of small airway epithelial cells and fibrous tissue, leading to epithelial injury and inflammation (2,3). These pathological changes result in fixed airflow obstruction. Clinically, BOS presents with progressive dyspnea and nonproductive cough, along with obstructive pulmonary function abnormalities (4). BOS is a major contributor to HSCT-related mortality and significantly impacts patients’ functional capacity and quality of life (5).

BOS often leads to thoracic air leak syndrome (TALS), which includes spontaneous pneumomediastinum, pneumopericardium, subcutaneous emphysema, interstitial emphysema, and spontaneous pneumothorax (6,7). Inappropriate positive pressure ventilation can cause excessive pressure on fragile bronchial tissues, leading to TALS and poor outcomes. However, there are no established guidelines or case reports on optimal mechanical ventilation for these patients. Providing safe general anesthesia in BOS cases can be challenging. This case aims to highlight the need for an appropriate ventilation strategy in patients with severe BOS during general anesthesia. We present this article in accordance with the CARE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-607/rc).

Case presentation

In February 2024, a 6-year-old boy was referred to the Department of Ophthalmology with an 8-month history of bilateral blurred vision. The primary diagnosis was cataract due to cGVHD in both eyes.

The patient was diagnosed with acute lymphoblastic leukemia in January 2021 and underwent HSCT from his father in June 2021. In November 2021, the child developed respiratory difficulties. Oscillometric lung function tests showed: Z at 5 Hz was 1.47 kPa/(L·s) (108.4% of predicted), X at 5 Hz was −0.81 kPa/(L·s) (173.7% of predicted), R at 5 Hz was 1.23 (97.1% of predicted), and R at 20 Hz was 0.92 (119.3% of predicted). cGVHD-related lung injury was considered, and oral glucocorticoid therapy was initiated. In March 2022, after a reduction in corticosteroid dosage, the patient experienced wheezing and resting dyspnea. Oscillometric lung function testing revealed: Z at 5 Hz was 1.89 kPa/L/s (160.3% of predicted), X at 5 Hz was −1.37 kPa/L/s (327.0% of predicted), R at 5 Hz was 1.29 (117.6% of predicted), and R at 20 Hz was 0.75 (75.2% of predicted), indicating increased peripheral airway resistance and decreased lung compliance. The Department of Respiratory and Critical Care Medicine at Peking University People’s Hospital made a diagnosis of BOS. Subsequent visits to the Children’s Hospital, Capital Institute of Pediatrics, and the National Center for Children’s Health, China, all confirmed the BOS diagnosis. The child continued treatment at our hospital, but his breathing difficulties gradually improved. In March 2023, pulmonary function tests showed: forced vital capacity (FVC) at 22.9% of predicted, forced expiratory volume in the first second (FEV₁) at 210 mL (25.2% of predicted), and an FEV₁/FVC ratio of 93.97%. Respiratory physicians then considered pulmonary function tests might increase the risk of TALS and discontinued them. The child gradually developed significant limitations in daily activities. His current medications include methylprednisolone 3 mg daily, tacrolimus, and ruxolitinib.

The patient was a 107 cm, 32 kg (body mass index 27.95 kg/m²) boy with a pulse rate of 85 beats per minute, blood pressure of 121/80 mmHg, respiratory rate of 20 breaths per minute, and a body temperature of 36.3 ℃. Lung auscultation revealed weak breath sounds. Airway assessment showed Mallampati grade II, mouth opening of 3 fingers, no neck mobility limitation, and a thyromental distance of 3 cm. Due to obesity, BOS, and visual impairment, he had limited physical activity, walking less than 100 meters on flat ground. The child had no history of sleep disorders or sleep apnea.

Preoperative blood gas analysis revealed hypercapnia (partial pressure of carbon dioxide, 48 mmHg; bicarbonate, 27.7 mmol/L). Other laboratory tests were unremarkable, and bacterial cultures and antibody testing ruled out pulmonary infection. A transthoracic echocardiogram in January 2024 revealed an ejection fraction of 63%, a pulmonary artery trunk diameter of 21 mm, a peak pulmonary artery flow velocity of 76 cm/s, and mild tricuspid regurgitation. A chest computed tomography in January 2024 showed multiple patchy areas of decreased lung density.

Upon admission to the operating room, the patient’s vital signs, including non-invasive blood pressure, limb-lead electrocardiogram, and pulse oximetry, were continuously monitored. Preoperative measurements were: heart rate 110 beats per minute, blood pressure 118/80 mmHg, and pulse oxygen saturation (SpO₂) at 96%. Before anesthesia induction, preoxygenation was performed using an oxygen reservoir mask. To maximize inhaled oxygen concentration, the mask was sealed on both sides to minimize leakage (Figure 1), rapidly increasing SpO₂ to 100%. After establishing peripheral intravenous access, anesthesia was induced with 90 mg propofol, 20 mg rocuronium, and 40 µg remifentanil. Anesthesia was maintained with continuous infusions of propofol and remifentanil, while ventilation was managed using a Leon Plus anesthesia machine (Plus NEO, Löwenstein Medical, Bad Ems, Germany).

Figure 1 The child was lying on the operating table and receiving preoxygenation. This image is published with the consent of the patient’s legal guardian.

Pressure-controlled ventilation-volume guaranteed (PCV-VG) mode was used, delivering 100% oxygen at a flow rate of 3 L/min. Inspiratory pressure was set to 30 mbar, targeting a tidal volume of 200 mL (6 mL/kg). No positive end-expiratory pressure (PEEP) was applied. The respiratory rate was adjusted to 18 breaths per minute based on end-tidal carbon dioxide partial pressure (P_ETCO₂), and the inspiratory-to-expiratory ratio was set at 1:1.6 to optimize inspiratory time while avoiding intrinsic PEEP (Figure 2). The surgery lasted about 55 minutes, with stable vital signs throughout. P_ETCO₂ was maintained at approximately 33 mmHg, and peak airway pressure was consistently around 22 mbar.

Figure 2 Respiratory parameters displayed on the anesthesia machine during the surgery.

Post-surgery, the child was transferred to the intensive care unit with intubation. Two hours later, the child regained consciousness, followed commands, and showed stable vital signs and normal blood gas results. The endotracheal tube was then safely removed, and the child was discharged the next day.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the parents of the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

We report a case of intraoperative anesthesia management in a pediatric patient with severe BOS. BOS is a condition characterized by persistent airflow limitation following HSCT. It leads to reduced small airway compliance, increasing the risk of airway rupture. However, high airway resistance necessitates elevated airway pressures, which further exacerbates the risk of barotrauma in these already fragile airways. Airway rupture, including pneumothorax and mediastinal emphysema, can lead to catastrophic outcomes in BOS patients. Intraoperative ventilation must balance high airway pressures and inadequate ventilation.

There is no clear consensus on the optimal mechanical ventilation mode for critically ill children (8). Although pressure-controlled ventilation (PCV) is widely used in acute respiratory distress syndrome patients, its main drawback is the inability to ensure consistent tidal volumes. Especially during surgery, stress responses and position changes can lead to inadequate ventilation or over-ventilation in PCV mode, which can be harmful to vulnerable patients. Spontaneous breathing may be considered in some procedures, such as in children with idiopathic bronchiolitis undergoing non-intubated general anesthesia (9), and in a patient with scleroderma from cGVHD (10). However, during ophthalmic surgery, the use of muscle relaxants and endotracheal intubation was necessary to prevent inadvertent movement.

We used the PCV-VG mode, which combines the advantages of volume-controlled ventilation (VCV) and PCV, providing stable tidal volumes through a decelerating gas flow pattern (11). By calculating respiratory compliance, the ventilator uses the lowest pressure to deliver the preset tidal volume (12). A prospective randomized study comparing PCV, PCV-VG, and VCV in optimizing respiratory mechanics showed that PCV-VG reduced airway peak pressures in infants and young children in the prone position, optimized dynamic compliance, and provided more stable tidal volumes (13). Similar results have been observed in laparoscopic surgery with Trendelenburg positioning (11) and in pediatric one-lung ventilation (14). We did not use PEEP and recruitment maneuvers due to obstructive fibrous tissue in the bronchioles, which reduces elasticity and could lead to pneumothorax.

After tracheal intubation, we immediately adjusted the inspiratory-to-expiratory ratio based on the flow-time and pressure-time curves to ensure that expiratory flow and pressure returned to zero before initiating inspiration. We ultimately used an inspiratory-to-expiratory ratio of 1:1.6. In routine surgeries, the inspiratory-to-expiratory ratio is typically set at 1:2 to promote gas expulsion by extending expiratory time, but this shortens inspiratory time. For this child, a shorter inspiratory time would increase driving pressure and lung injury risk. By real-time monitoring flow-time and pressure-time curves, we ensured adequate gas expulsion, prevented intrinsic PEEP and high driving pressure. This strategy reflects individualized intraoperative respiratory management.

We didn’t use a laryngeal mask airway (LMA) in this case. In BOS patients, airway pressures can rise significantly due to increased resistance, exceeding the LMA’s sealing capacity and compromising ventilation. Additionally, the LMA is often avoided in obese patients due to positioning challenges. The endotracheal tube primarily affects dynamic compliance, not static compliance, so the lungs are not at risk from increased driving pressure.

Conclusions

A successful anesthetic management of a pediatric patient with severe BOS undergoing general anesthesia for ophthalmic surgery was reported, providing an alternative ventilation management strategy in such population. Ensuring adequate gas exchange while minimizing airway pressure, and individualized management of ensuring pulmonary gas expulsion are priorities for intraoperative safety in patients with BOS.

Acknowledgments

We sincerely appreciate the trust bestowed upon us by the child and his families to administer anesthesia for this operation.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-607/rc

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-607/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-607/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the parents of the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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