Hypoxemia during one-lung ventilation (OLV) is normal.1 Different ways of improving SpO2 on OLV include intermittent inflation of the collapsed lung with oxygen, lung recruitment, and application of continuous positive airway pressure (CPAP) to the nondependent lung.2–5 This case report described the use of CPAP to the right lung, which was converted to high-frequency jet ventilation (HFJV) of the middle and lower lobes during right upper lobe sleeve resection.
A 73-year-old man (body weight 65 kg, height 155 cm) was scheduled for upper lobotomy of the right lung. He had a 20-year history of chronic obstructive pulmonary disease (COPD), and coronary artery disease for 10 years. Preoperative arterial blood gases (on FiO2 0.21) showed a PaO2 of 80 mmHg and PaCO2 of 30 mmHg. Preoperative pulmonary function testing showed a one-second forced expiratory volume of 1.43 L (55% of predicted). Anesthesia was induced with intravenous midazolam 2 mg, etomadate 12 mg and fentanyl 0.2 mg. Neuromuscular blockade was achieved with vecuronium 6 mg. Anesthesia was maintained with isoflurane, fentanyl, and propofol. According to the patient's weight, height, and X-ray findings, we chose a left-sided 37F double-lumen tube (Broncho-Cath®, Mallinckrodt, Ireland). Double-lumen tube placement was checked by traditional inspection and auscultation. Correct position and depth of the double-lumen endobronchial tube (DLT) in the left main bronchus was verified fiberoptically in both supine and left lateral decubitus positions.
During two-lung ventilation, the exhaled tidal volume was 600 ml with a peak inspiratory pressure of 16 cmH2O and a respiratory rate of 12 breaths/min. SpO2 was 100%, and partial pressure of end-tidal carbon dioxide (PetCO2) was 35 cmH2O. Arterial blood gases (on FiO2 1.0) were normal. Twenty minutes into OLV, SpO2 decreased from 100% on two-lung ventilation to 75%-80%. The patient was ventilated with a tidal volume of 550 ml, a respiratory rate of 16 breaths/min, and peak airway pressures of 30 cmH2O. Good position of the DLT was demonstrated by urgent bronchoscopy. We administered 5 cm H2O CPAP to the nondependent lung, and SpO2 improved to 95%-96%, with PetCO2 40 cmH2O. CPAP was decreased to 3 cmH2O, and SpO2 remained at 95%-96%. Arterial blood gas showed PaO2 of 88 mmHg, and PaCO2 of 45 mmHg, conditions satisfactory for surgery.
Unfortunately, a sleeve resection was necessary, and CPAP was no longer feasible. Discontinuation of CPAP resulted in desaturation in five minutes. An airway exchange catheter was placed in the bronchus intermedius; however, the catheter and fiberoptic bronchoscope were too large to be passed concurrently through the tracheal lumen of the DLT. Location of the catheter in the bronchus was determined by the thoracic surgeons. This allowed for HFJV of the middle and lower lobes with the bronchus open (Figure 1). The Jet Ventilator (Tyco Ltd., China) was used, with a respiratory rate of 120 breaths/min, I:E=1:2, and driving pressure of 1 mbar (1 mbar = 0.1 kPa, Figure 2). SpO2 immediately improved to 98%-99%, and surgical exposure was adequate. PetCO2 was 42 cmH2O, blood gas showed normal PaO2 (92 mmHg) and PaCO2 (42 mmHg). Inflation of the middle and lower lobes was observed. HFJV was continued until clamping of the supplying pulmonary artery, and improvement in the SaO2. The patient was extubated in the operating room, and was transferred to the thoracic ward. The remainder of the patient's hospital course was uneventful, and he was discharged on the eighth postoperative day.
Although this patient had an obstructive pattern on preoperative pulmonary function tests, he developed hypoxemia on OLV. The hypoxemia was corrected with application of CPAP to the nondependent lung; however, a sleeve resection was necessary, and CPAP could no longer be maintained with the open bronchus exposed to atmospheric pressure. HFJV provided satisfactory oxygenation and good surgical access during OLV for thoracotomy.
In this patient, selective HFJV to the right middle and lower lobes was compatible with selective lobe collapse of the right upper lobe. This not only maintained oxygenation, but also provided optimal surgical access by collapsing the right upper lobe. It was achieved by passing a catheter of adequate length so that its tip would lie well within the bronchus intermedius and beyond the surgical incision in the right main bronchus. The location of the catheter in the bronchus was determined by the surgeons. Although the lower and middle lobes were inflated, there was minimal respiratory movement, and with the right upper lobe collapsed, there was adequate surgical exposure and good operative conditions. Care was taken to ensure proper positioning of the catheter by the anesthesiologists and surgeons. The catheter secured to prevent distal migration into a single lobe, which would have further increased the risk of barotrauma.
Although the use of a ventilating catheter passed into the distal bronchus for tracheal and carinal resection has been described, this case shows an adaptive treatment of hypoxemia on OLV by placement of the catheter in the bronchus intermedius. The indications for HFJV are expanded beyond ventilating both lungs or a single lung, to that of ventilating two lobes.6–8 In patients with difficulty in CO2 elimination, we should attempt to prevent hypercarbia by increasing the driving pressure (DP) of jet ventilation as long as HFJV is required. Furthermore, DP settings above 405.3 kPa (4.0 atm) are usually not available. If the measure is not successful, two-lung ventilation should be applied until normocarbia is achieved. Patients with no difficulty in CO2 elimination tolerate a lower or successively lowered DP. This measure distinctly lowers airway pressure, thus reducing the risk of barotrauma, providing less cooling and drying of the tracheobronchial epithelium, and providing satisfactory operative conditions.9
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