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From the Department of Anesthesia, Montreal General Hospital, McGill University Health Centre, Montréal, Québec, Canada.
Address correspondence to: Dr. P. Ruiz, Montreal General Hospital, Department of Anesthesia, 1650, avenue Cedar, Room D10 165.3, Montréal, Québec H3G 1A4, Canada. Phone: 514-934-1934, ext. 43261; Fax: 514-934-8249; E-mail: ppruizmd{at}aol.com
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Abstract |
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Clinical features: A 69-yr-old male with lung cancer, emphysema and obstructive sleep apnea, presented for a right upper lobectomy. His history was also positive for a left lower lobectomy six years previously. Intraoperative lung isolation was achieved using a 41 F left double-lumen tube (DLT). Monitoring the respiratory mechanics allowed for continuous adjustment of ventilator settings during the various phases of the surgery avoiding the risks of barotrauma and volutrauma. Problems with oxygenation occurred during one-lung ventilation.
Conclusion: This case report shows that a severe level of hypoxemia and hypercarbia associated to lung mechanical property changes can be observed during the OLV phase. Application of continuous positive airway pressure on the non-dependent lung partially corrected blood oxygenation. Lobe isolation techniques should be considered as useful options for intraoperative airway management for these patients.
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Introduction |
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Clinical features |
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TOPAbstractIntroductionClinical featuresDiscussionReferences |
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Upon arrival in the operating room an iv radial artery cannula and a T5–6 epidural catheter1 were inserted. Propofol, fentanyl and rocuronium were used to induce anesthesia. A 41-F left double lumen tube (DLT) was inserted. Anesthesia was maintained with a remifentanil and propofol infusion, plus epidural boluses of 2% lidocaine with epinephrine. The patient was ventilated with FIO2 an of 1.0 throughout. Arterial blood gas analysis was performed during supine left OLV, and at the end of DLT inspection and lung auscultation, SpO2 dropped to 91%, PO2 to 58 mmHg, with a PCO2 of 39 mmHg. SpO2 returned to normal as TLV was resumed, and ventilator settings were adjusted to a tidal volume (TV) of 600 mL, aiming for an inspiratory pressure plateau lower than 30 cm H2O, rate of 8·min–1 and I: E ratio 1:2.5. Fibreoptic bronchoscopy (FOB) confirmed correct DLT position.
We recorded the respiratory mechanics from a Datex-Ohmeda Captomac Ultima monitor M-CAiOV model (Bromma, Sweden) and calculated respiratory compliance dividing the TV by the inspiratory airway plateau pressure. After TLV resumed, arterial blood gases and respiratory mechanics were obtained in the supine position (Table
). The DLT position was re-checked using FOB after lateral positioning of patient. Ten minutes after lateral positioning and establishment of TLV, arterial gases and respiratory mechanics were again recorded (Table). With OLV, TV was adjusted, aiming for a plateau pressure below 30 cm H2O. Ten minutes of OLV produced a decrease in SaO2 (88%), PaO2 (57 mmHg) and compliance (14 mL·cm H2O–1) and increase in PaCO2 (66 mmHg) respiratory resistance (36 mL·sec–1·cmH2O–1) and airway plateau pressure (22 cm H2O) (Table). Again, FOB confirmed correct DLT positioning. Extensive bronchial secretions were suctioned from the dependent lung. After manual partial re-expansion of the non-dependent lung, 5 cm H2O CPAP was applied, with an increase of PaO2 to 74 mmHg and SpO2 to 93%. At this point, PCO2 was 60 mmHg, and values for airway pressure plateau, compliance, and resistance were 18, 18 and 32 respectively (Table). These values remained constant throughout the right upper lobectomy (approximately 90 min). At the request of the surgeon CPAP 5 cm H2O was removed, with immediate worsening of SpO2 (89%), PaO2 (63 mmHg) and PaCO2 (63 mmHg). Airway plateau pressure, compliance, and resistance were 25 cm H2O, 14 mL·cm H2O–1 and 23 mL·sec–1·cm –1 H2O, respectively (Table). Oxygenation improved when TLV was restarted. Although the respiratory rate was increased to 15·min–1, PaCO2 was 57 mmHg during TLV, probably due to bronchial secretions. Plateau pressure was 20 cm H2O, compliance was 32 mL·cm H2O–1 and resistance was 21 mL·sec–1·cm H2O–1 (Table). Hematocrit dropped from 48% to 42% and there were no clinically significant cardiovascular changes during surgery. The patient was extubated in the operating room with adequate analgesia, spent six hours in the postanesthesia care unit, and was discharged after an uncomplicated hospital stay on the fifth postoperative day.
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Discussion |
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After lung resection, a series of cardiopulmonary changes and adaptations are expected to occur in the remaining lung tissue, and are a function, in part, of the size of lung resection. Our patient’s stress echocardiogram test was aborted due to exertional dyspnea, and during the ventilatory exercise studies, he exercised only to 53% of predicted VO2 max. He developed an abnormal response with marked hyperventilation and desaturation to 87%. Reduced exercise tolerance after pulmonary resection is related to pulmonary hypertension.4 Changes in hemodynamics, before and after pulmonary resection, do not necessarily correlate with changes in pulmonary function, making it more difficult to predict perioperative complications. Patients with a normal preoperative PFT may have cardiovascular decompensation.2 Response to the stress test in our patient can be explained based upon this finding. Some attribute reduced stroke volume index after pneumectomy to impaired filling of the left ventricle consequent to reduced pulmonary blood volume.4 The same occurs after lobectomy, although less significantly.4 Other potential changes after pneumectomy include decrease in lung diffusion capacity, and elevation in right heart pressure during exercise.2
After OLV was established, we expected to observe changes in gas exchange. As seen in this case, the level of hypoxemia and hypercapnia can reach critical levels very rapidly. When supine, during DLT position assessment, desaturation became critical shortly after OLV. Arterial gas analysis should have been utilized at this point as a predictor for gas exchange during intraoperative OLV in the lateral position, and a different approach for right lung isolation could have been planned at that time. A selective endobronchial blocker prior to turning the patient on lateral decubitus should have been considered.
When dealing with lung isolation for contralateral lung resection, it is also important to consider respiratory mechanics. A summation of factors can render lung isolation more dangerous than usual OLV. Tidal volume may be delivered to pulmonary parenchyma that is not prepared to recruit more alveolar units, as a result of maximum expansion after previous resection. This situation can lead to barotrauma, ventilation/perfusion mismatch, and increases in pulmonary vascular resistance, leading to ventilatory and hemodynamic compromise. If a DLT is used to achieve lung isolation, it is important to record baseline flow-volume loops, and to monitor respiratory mechanics, before and during lung isolation. One should also be prepared to adjust ventilator settings before complications arise. While inspiratory peak pressure and inspiratory plateau pressure are both useful, the latter is less influenced by DLT flow resistance. The ideal ventilation mode is pressure control ventilation. In pressure control mode, if there is a reduction in delivered TV, or if in volume control mode inspiratory plateau levels rise above 30 cm H2O, one should first exclude DLT malposition by FOB examination. Afterward, a new ventilatory strategy should be instituted, minimizing inspiratory pressures with low TV and high respiratory rate. During lung isolation, there is also a risk of a life-threatening pneumothorax in the dependent hemithorax. High inspiratory plateau pressures might be associated with high pulmonary vascular resistance, increasing afterload to the right ventricle, further compromising its function due to hemodynamic adaptations occurring in response to previous pulmonary resection. Different from OLV, when there are two or three lobes from which the vascular bed can be recruited to adjust right ventricular output, in one-lobe ventilation there is minimal reserve of the vascular bed that can be recruited to reduce right ventricle afterload.
Campos5 successfully managed a critical situation by isolating the lobe to be resected using a Univent tube (Fuji Systems Corp., Tokyo, Japan) in a patient with bronchial hemorrhage and previous contralateral lobectomy. That patient did not maintain adequate oxygenation during total lung isolation even after application of CPAP, different from our patient. Later, the same author investigated the effects on oxygenation during selective lobar vs total lung collapse, with and without CPAP. He observed higher arterial oxygen tension with selective lobar isolation.6 Isolation of the lobe to be resected, and ventilation of the remaining lung is a reasonable alternative to be considered. McGlade and Slinger recently described the successful management of a case similar to ours.7 They used a left DLT combined with an Arndt wire-guided endobronchial blocker (Cook, Bloomington, IN, USA) to isolate the lobe to be resected. During the right upper lobectomy, 2 cm H2O CPAP was applied to the middle and lower right lobes through the bronchial blocker (BB). The removal of CPAP at the surgeon’s request provoked a worsening of oxygenation only 15 min after beginning one-lobe ventilation, at levels similar to our case. Lobar isolation techniques make ventilation of non-dependent lung areas possible to deliver better oxygenation, although with more technical difficulty and with a higher risk of intraoperative BB dislocation. Correcting BB dislocation in a patient in the lateral position is not always simple, particularly when devices such as the Arndt BB are used. Arndt BB positioning depends upon the orientation of the blocker by FOB, using the wire loop located at the BB tip.8 Once the blocker is positioned, the wire is removed, making BB repositioning impossible.
In conclusion, in a patient with a previous contralateral lung resection monitoring respiratory mechanics allowed continuous adjustment of the ventilator settings during the various phases of surgery, avoiding the risks of barotrauma and volutrauma. Changes in respiratory mechanics and gas exchange are anticipated if contralateral lung isolation is established with a DLT in patients with previous lung resection. Lobe isolation techniques should be considered useful options, keeping in mind though, that a BB might be associated with difficulties in maintaining lobe isolation due to intraoperative dislocation of the blocker position.
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Acknowledgments |
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Footnotes |
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References |
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2 Nishimura H, Haniuda M, Morimoto M, Kubo K. Cardiopulmonary function after pulmonary lobectomy in patients with lung cancer. Ann Thorac Surg 1993; 55: 1477–84.[Abstract]
3 Hagihira S, Maki N, Kawaguchi M, Singer P. Selective bronchial blockage in patients with previous contralateral lung surgery. J Cardiothorac Anesth 2002; 16: 638–42.
4 Heerdt PM. Cardiovascular adaptation to lung resection. In: Kaplan JA, Slinger PD (Eds). Thoracic Anesthesia, 3rd ed. Philadelphia: Churchill Livingstone Inc.; 2003: 423–35.
5 Campos JH, Ledet C, Moyers JR. Improvement of arterial oxygen saturation with selective lobar bronchial block during hemorrhage in a patient with previous contralateral lobectomy. Anesth Analg 1995; 81: 1095–6.[Medline]
6 Campos JH. Effects on oxygenation during selective lobar versus total lung collapse with or without continous positive airway pressure. Anesth Analg 1997; 85: 583–6.[Abstract]
7 McGlade DP, Slinger PD. The elective combined use of a double lumen tube and endobronchial blocker to provide selective lobar isolation for lung resection following contralateral lobectomy. Anesthesiology 2003; 99: 1021–2.[Medline]
8 Arndt GA, Kranner PW, Rusy DA, Love R. Single-lung ventilation in a critically ill patient using a fiberoptically directed wire-guided endobronchial blocker. Anesthesiology 1999; 90: 1484–6.[Medline]
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