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Problems with CPAP during one-lung ventilation in thoracoscopic surgery
LETi'ERS TO THE EDITOR
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Problems With CPAP During One-Lung Ventilation in Thoracoscopic Surgery To the Editor: Thoracoscopic operations are increasingly performed each year because they appear to be associated with less postoperative pain and shorter hospitalization compared with open thoracotomies. We have noted that anesthetic management of one-lung ventilation during these procedures often requires some added considerations. Unlike during an open procedure, the operative lung must be completely collapsed before thoracoscopy to allow insertion of the trochars, provide adequate surgical visualization, and prevent lung injury. Moreover, even with optimal placement of a double-lumen tube, incomplete lung collapse is often a problem. During open thoracotomy, the surgeon can manually assist lung collapse; however, during thoracoscopy, this is not possible and the small operative ports limit both air entry into the chest and the rate of lung deflation. We often find it necessary to actively deflate the lung with intermittent low levels of suction. Management of hypoxemia during one-lung ventilation can also be problematic. Although 5 to 10 cm H20 of continuous positive airway pressure (CPAP) is recommended during open thoracotomy, 1we have often found that even low levels of CPAP (5 cm H20) to the nonventilated lung causes enough re-expansion of the lung to impede the surgeon's already limited operative view. We resort to either 5 cm H20 of positive end-expiratory pressure (PEEP) to the ventilated lung or periodic reinflation of the lung on the operative side.
John Bailey, MD Chief Resident, Anesthesiology Maged Mikhail, MD Associate Professor of Anesthesiology Steven Haddy, MD Assistant Professor of Anesthesiology Duraiyah Thangathurai, MD Professor and Vice-Chairman of Anesthesiology Department of Anesthesiology University of Southern California USC University Hospital Los Angeles, CA REFERENCES
1. AlferyDD, BenumofJL, TrousdaleFR: Improvingoxygenationduringone-lungventilation:The effects of PEEP madblood flow restrictionto the nonventilatedlung.Anesthesiology55:381, 1981
Comparison of Lumbar and Thoracic Epidural Narcotics for Postoperative Analgesia in Patients Undergoing Abdominal Aortic Aneurysm Repair To the Editor: We read the article by Gold et al 1 and the accompanying editorial by Kahn and Hollier2 with interest. We feel that both deserve comment. The study by Gold et al involved the random assignment of abdominal aortic aneurysm repair patients to bolus epidurai morphine administered either by the thoracic or lumbar route. In their introduction, Gold et al attribute possible decreases in morbidity to the superior analgesia provided by epidural opioids. Their assessments showed better pain control at times in the lumbar group, leading them to conclude that there is no advantage to the thoracic route for epidural administration of morphine. Given the above flawed premise for the study and the numerous limitations of its design, this conclusion is not surprising. In fact, as the authors noted, several previous studies have shown equivalent analgesia whether the lumbar or thoracic route is used for epidural opioid alone. 3-8 There are several limitations to this study. Morphine was administered by bolus injection, which provides inferior results compared with a continuous morphine infusion.9 In addition, opioid alone was used, without local anesthetic. Epidural analgesia is most likely to be associated with a decrease in morbidity when a combination of local anesthetic and opioid is administered by continuous infusion via a catheter inserted at the dermatomes involved in the surgical incision3°-12Benefits shown in studies using opioid/local anesthetic combinations include: decreased thrombotic complications, quicker return of bowel function, improved pain control with activity and a faster return to ambulation, less cardiac and pulmonary morbidity, and shorter ICU and hospital stays32 Gold et al did not assess these parameters. Thus, the current study shows a limited view of the benefits of epidural analgesia, and does not assist clinicians in deciding upon a specific epidural analgesic technique.
239
Problems With CPAP During One-Lung Ventilation in Thoracoscopic Surgery To the Editor: Thoracoscopic operations are increasingly performed each year because they appear to be associated with less postoperative pain and shorter hospitalization compared with open thoracotomies. We have noted that anesthetic management of one-lung ventilation during these procedures often requires some added considerations. Unlike during an open procedure, the operative lung must be completely collapsed before thoracoscopy to allow insertion of the trochars, provide adequate surgical visualization, and prevent lung injury. Moreover, even with optimal placement of a double-lumen tube, incomplete lung collapse is often a problem. During open thoracotomy, the surgeon can manually assist lung collapse; however, during thoracoscopy, this is not possible and the small operative ports limit both air entry into the chest and the rate of lung deflation. We often find it necessary to actively deflate the lung with intermittent low levels of suction. Management of hypoxemia during one-lung ventilation can also be problematic. Although 5 to 10 cm H20 of continuous positive airway pressure (CPAP) is recommended during open thoracotomy, 1we have often found that even low levels of CPAP (5 cm H20) to the nonventilated lung causes enough re-expansion of the lung to impede the surgeon's already limited operative view. We resort to either 5 cm H20 of positive end-expiratory pressure (PEEP) to the ventilated lung or periodic reinflation of the lung on the operative side.
John Bailey, MD Chief Resident, Anesthesiology Maged Mikhail, MD Associate Professor of Anesthesiology Steven Haddy, MD Assistant Professor of Anesthesiology Duraiyah Thangathurai, MD Professor and Vice-Chairman of Anesthesiology Department of Anesthesiology University of Southern California USC University Hospital Los Angeles, CA REFERENCES
1. AlferyDD, BenumofJL, TrousdaleFR: Improvingoxygenationduringone-lungventilation:The effects of PEEP madblood flow restrictionto the nonventilatedlung.Anesthesiology55:381, 1981
Comparison of Lumbar and Thoracic Epidural Narcotics for Postoperative Analgesia in Patients Undergoing Abdominal Aortic Aneurysm Repair To the Editor: We read the article by Gold et al 1 and the accompanying editorial by Kahn and Hollier2 with interest. We feel that both deserve comment. The study by Gold et al involved the random assignment of abdominal aortic aneurysm repair patients to bolus epidurai morphine administered either by the thoracic or lumbar route. In their introduction, Gold et al attribute possible decreases in morbidity to the superior analgesia provided by epidural opioids. Their assessments showed better pain control at times in the lumbar group, leading them to conclude that there is no advantage to the thoracic route for epidural administration of morphine. Given the above flawed premise for the study and the numerous limitations of its design, this conclusion is not surprising. In fact, as the authors noted, several previous studies have shown equivalent analgesia whether the lumbar or thoracic route is used for epidural opioid alone. 3-8 There are several limitations to this study. Morphine was administered by bolus injection, which provides inferior results compared with a continuous morphine infusion.9 In addition, opioid alone was used, without local anesthetic. Epidural analgesia is most likely to be associated with a decrease in morbidity when a combination of local anesthetic and opioid is administered by continuous infusion via a catheter inserted at the dermatomes involved in the surgical incision3°-12Benefits shown in studies using opioid/local anesthetic combinations include: decreased thrombotic complications, quicker return of bowel function, improved pain control with activity and a faster return to ambulation, less cardiac and pulmonary morbidity, and shorter ICU and hospital stays32 Gold et al did not assess these parameters. Thus, the current study shows a limited view of the benefits of epidural analgesia, and does not assist clinicians in deciding upon a specific epidural analgesic technique.