Review Article

A 22-yr-old woman with Eisenmenger’s syndrome, secondary to a sinus venosus atrial septal defect (ASD), presented for bilateral sequential lung transplantation and ASD repair. A comprehensive prebypass transesophageal echocardiographic (TEE) examination revealed marked right ventricular dilation and hypertrophy, with a large sinus venosus ASD measuring 3.5 cm, with two-way interatrial flow though the ASD throughout the cardiac cycle, and probable anomalous right-sided pulmonary venous drainage. Right and left pulmonary vein (PV) peak velocities were normal (<75 cm/s). There was mild-to-moderate right ventricular impairment. The ASD repair was achieved with a bovine pericardial patch. The surgeon found no evidence of anomalous pulmonary venous drainage, but during lung allograft implantation the right PV anastomosis required a pericardial patch because of insufficient length. Initial mechanical ventilation and weaning from bypass was uneventful. The initial postbypass TEE examination revealed good left and right ventricular function, no evidence of a residual ASD, and minimal left-sided air. A preliminary color Doppler examination of the left and right PV anastomoses seemed satisfactory. However, a second review at about 5 min after weaning from bypass identified prominent turbulent flow from the left, and to a lesser extent, right PVs, with a peak PV velocity of 267 cm/s, indicating a left PV anastomosis gradient of 28 mm Hg (Fig. 1; Video Clip 1; please see video clip available at www.anesthesia-analgesia.org ). Further TEE examination identified dehiscence of the ASD repair with florid left-to-right flow throughout the cardiac cycle (Video Clip 2; please see video clip available at www.anesthesia-analgesia.org ). The surgeon was notified of these findings and bypass was reinstituted to revise the ASD repair. The anesthesiologist also raised a concern regarding the high-velocity PV flows, indicating probable PV kinking or stenosis and the risk of early pulmonary allograft failure. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- A discussion between the anesthesiologist and surgeon ensued, both considering the possibility that excessive pulmonary blood flow secondary to the left-to-right shunt could explain the high velocity PV flows. A decision was made to wean from bypass after the revised ASD repair, and to repeat the TEE examination and remeasure the PV flows. There was then clear resolution of turbulent flow and normal PV anastomotic diameters (>0.5 cm), and the left and right PV peak velocities reduced to <80 cm/s. Surgery was otherwise completed uneventfully and the patient made a good postoperative recovery. TEE has become near-routine in lung transplantation, with a special focus on RV function, the existence of a patent foramen ovale and, most importantly, the quality of the pulmonary vascular anastomoses.1–4 Although the left upper PV is commonly evaluated in a four-chamber view at about 10 to 50 degrees, a more comprehensive view of both upper and low left PVs can be achieved with the transducer array at about 110 degrees and the TEE probe rotated to the extreme left. Similarly, the right PVs can be visualized at about 45 to 60 degrees with the TEE probe rotated to the extreme right. Each of these approaches visualizes the respective upper and lower PVs as an inverted “V” and is ideal for Doppler measurements. Continuous wave Doppler is preferable when estimating a maximal gradient. Restricted pulmonary venous drainage at the anastomosis site may be due to stenosis or kinking, which can result in pulmonary edema and impaired gas exchange after pulmonary allograft implantation. The PV and right pulmonary arterial anastomoses can be visualized with TEE in most cases.1,2 Michel-Cherqui et al.2 evaluated the pulmonary vascular anastomoses in 18 patients during lung transplantation. All right arterial (n = 13) anastomoses were visualized; one had a moderate stenosis but this did not require reoperation. Of the 22 pulmonary venous anastomoses, 16 were considered normal with a diameter more than 0.5 cm and peak systolic flow velocity <100 cm/s. In 5 patients, the PV anastomoses were abnormal but did not require reoperation because of modest PV pressure gradients (<12 mm Hg) and early allograft function being within normal limits. One patient had markedly impaired gas exchange in which severe PV stenosis was identified; this led to revision of the PV anastomosis and resolution of the allograft dysfunction.2 Miyaji et al.4 performed intraoperative TEE on 17 patients during living-donor lobar lung transplantation, using the ratio of peak flow velocities through bilateral PV anastomoses as an indicator of vascular stenosis. By placing the sample volume at the level of each PV anastomosis, they calculated the ratio of the larger to smaller peak velocity as the flow velocity index. Three of 17 patients had a high flow velocity index (>1.5); 2 of these had a kink in a PV anastomosis and 1 had atelectasis of the transplanted lobe.

In our experience, there are some occasions when there is relatively high (80–140 cm/s) peak PV flows during the second lung implantation with bilateral sequential transplant procedures because, with contralateral pulmonary artery clamping, the entire cardiac output is traversing the first implanted ventilated lung. This will artificially increase PV flow and may raise unnecessary concerns regarding the quality of the PV anastomosis. A definitive evaluation of the PV anastomoses is best done with two-lung blood flow and ventilation.

A PV diameter of <0.25 cm has been suggested as the critical threshold for pulmonary allograft failure.3 In any case, unilateral postimplantation pulmonary edema should prompt TEE evaluation of the PV anastomoses. If kinking or stenosis of the PV is demonstrated, then surgical revision can occur before the patient leaves the operating room. We have had several circumstances in our institution when this has occurred. Thus, the importance of the current case study, is that it highlights an alternative explanation for high velocity flow in the PV after lung transplantation. Our patient had high velocity PV flows secondary to a marked left-to-right shunt in the setting of normalized pulmonary vascular resistance after lung transplantation, via a disrupted ASD repair. REFERENCES 1. Leibowitz DW, Smith CR, Michler RE, Ginsburg M, Schulman LL, McGregor CC, Li Mandri G, Weslow RG, Di Tullio MR, Homma S. Incidence of pulmonary vein complications after lung transplantation: a prospective transesophageal echocardiographic study. J Am Coll Cardiol 1994;24:671–5 2. Michel-Cherqui M, Brusset A, Liu N, Raffin L, Schlumberger S, Ceddaha A, Fischler M. Intraoperative transesophageal echocardiographic assessment of vascular anastomoses in lung transplantation. A report on 18 cases. Chest 1997;111:1229–35 3. Huang YC, Cheng YJ, Lin YH, Wang MJ, Tsai SK. Graft failure caused by pulmonary venous obstruction diagnosed by intraoperative transesophageal echocardiography during lung transplantation. Anesth Analg 2000;91:558–60 4. Miyaji K, Matsubara H, Nakamura K, Kusano KF, Goto K, Date H, Ohe T. Equivalence of flow velocities through bilateral pulmonary vein anastomoses in bilateral living-donor lobar lung transplantation. J Heart Lung Transplant 2005;24:860–4

Background: One-lung ventilation (OLV) increases mechanical stress in the lung and affects ventilation and perfusion (V, Q). There are no data on the effects of OLV on postoperative / matching. Thus, this controlled study evaluates the influence of OLV on / distribution in a pig model using a gamma camera technique [single-photon emission computed tomography (SPECT)] and relates these findings to lung histopathology after OLV. Methods: Eleven anaesthetized and ventilated pigs (VT=10 ml kg-1, FIO2=0.40, PEEP=5 cm H2O) were studied. After lung separation, OLV and thoracotomy were performed in seven pigs (OLV group). During OLV and in a two-lung ventilation (TLV), control group (n=4) ventilation settings remained unchanged. SPECT with 81mKr (ventilation) and 99mTc-labelled macro-aggregated albumin (perfusion) was performed before, during, and 90 min after OLV/TLV. Finally, lung tissue samples were harvested and examined for alveolar damage. Results: OLV affected ventilation and haemodynamic variables, but there were no differences between the OLV group and the control group before and after OLV/TLV. SPECT revealed an increase of perfusion in the dependent lung compared with baseline (49-56%), and a corresponding reduction of perfusion (51-44%) in non-dependent lungs after OLV. No perfusion changes were observed in the control group. This resulted in increased low / regions and a shift of / areas to 0.3-0.5 (10-0.5-10-0.3) in dependent lungs of OLV pigs and was associated with an increased diffuse alveolar damage score. Conclusions: OLV in pigs results in a substantial / mismatch, hyperperfusion, and alveolar damage in the dependent lung and may thus contribute to gas exchange impairment after thoracic surgery.

The spread of sensory blockade after epidural injection of a specific dose of local anesthetic (LA) differs considerably among individuals, and the factors affecting this distribution remain the subject of debate. Based on the results of recent investigations regarding the distribution of epidural neural blockade, specifically for thoracic epidural anesthesia, we noted that the total mass of LA appears to be the most important factor in determining the extent of sensory, sympathetic, and motor neural blockade, whereas the site of epidural needle/catheter placement governs the pattern of distribution of blockade relative to the injection site. Age may be positively correlated with the spread of sensory blockade, and the evidence is somewhat stronger for thoracic than for lumbar epidural anesthesia. Other patient characteristics and technical details, such as patient position, and mode and speed of injection, exert only a small effect on the distribution of sensory blockade, or their effects are equivocal. However, combinations of several patient and technical factors may aid in predicting LA dose requirements. Based on these results, we have also formulated suggested epidural insertion sites that may optimize both analgesia and sympathicolysis for various surgical indications.

We report the case of a terminally ill cancer patient with recurrent pericardial and bilateral pleural effusions who was scheduled for video-assisted thoracoscopic surgery. The operation was performed with the patient awake under epidural anaesthesia. The patient’s cough reflex in response to lung manipulation was successfully minimised by the inhalation of aerosolised lidocaine. Video-assisted thoracic surgery requires the exclusion of a lung from ventilation. In order to support one-lung spontaneous ventilation in this high-risk patient, we successfully used non-invasive bilevel positive airway pressure ventilation via a facemask. Based on this preliminary experience, we think that critically ill patients scheduled for palliative surgery can be successfully managed with the combination of minimally invasive surgical techniques and neuraxial block with non-invasive lung ventilation.

ats-07.docAlam N, Park BJ, Wilton A, et al. Ann Thorac Surg 2007; 84: 1085-91

Objective: FEV1 measured on the first postoperative day has shown to be a better predictor of complications than traditional ppoFEV1. Therefore, its estimation before operation may enhance risk stratification. The objective of this study was to develop and validate a model to predict FEV1 on the first postoperative day after major lung resection. Methods: FEV1 was prospectively measured on the first postoperative day in 272 patients submitted for lobectomy or pneumonectomy at two centers. A random sample of 136 patients was used to develop a model estimating the first day FEV1 by using multiple regression analysis including several preoperative and operative factors. The model was then validated by bootstrap analysis and tested on the other sample of 136 patients. Results: Factors reliably associated with postoperative first day FEV1 were age (p=0.002), preoperative FEV1 (p<0.0001), the presence of epidural analgesia (p<0.0001), and the percentage of non-obstructed segments removed during operation (p=0.001). The following model estimating the first day postoperative FEV1 was derived: -2.648+0.295xage+0.371xFEV1+8.216xepidural analgesia-0.338xpercentage of non-obstructed segments removed during operation. In the validation set, the mean predicted first day postoperative FEV1 value did not differ from the observed one (42.6 vs 42.0, respectively; p=0.3) and the plot of the observed versus the predicted first day FEV1 showed a satisfactory calibration. Conclusions: We developed a model predicting the first day postoperative FEV1. If future analyses will prove its role in stratifying the early postoperative risk, it may be integrated in preoperative evaluation algorithms to refine risk stratification.

BACKGROUND: Left-sided double-lumen tubes are perceived to be safer than right-sided tubes, because they may be less prone to malposition. If this is true, then the incidence and severity of hypoxemia, hypercapnea, and high airway pressures should be higher for right-sided tubes during thoracic surgery than for left-sided tubes.

METHODS: We retrospectively reviewed thoracic surgical anesthetics between April 15, 2003, and December 31, 2004, using an automated anesthesia information management system. The system automatically records pulse oximetry, end-tidal carbon dioxide, and peak inspiratory pressure data every 30 s. Side of surgery and double-lumen tube placement are also documented. We compared the frequency of right- and left-sided Mallinckrodt tube use by thoracic anesthesiologists. Next, we examined the incidence, duration, and severity of hypoxemia (Spo2 <90%), hypercapnea (Etco2 >45 mm Hg) and high airway pressures (peak inspiratory pressure >35 cm H2O) for lung and chest wall surgery patients. Group counts and means were compared by standard statistical methods.

RESULTS: Right- (n = 241) and left- (n = 450) sided tubes were almost exclusively used on the side contralateral to surgery. There were no differences in the incidence or duration of hypoxemia, hypercarbia, or high airway pressures. There was a small but significant increase in Etco2 for patients having left lung ventilation.

CONCLUSIONS: The supposition that left-sided double-lumen tubes are safer than right-sided tubes when intraoperative hypoxemia, hypercapnea, and high airway pressures are used as criteria for safety is not supported by our data comparing the two types of tubes from one manufacturer.

Background: Diffusing capacity (Dlco), an independent predictor of morbidity after major lung resection, is not used routinely in preoperative evaluation because of a perceived lack of value in patients with normal spirometry. We evaluated the potential utility of measuring Dlco for assessment of operative risk in lung resection patients with normal spirometry. Methods: A retrospective review was conducted for patients undergoing lung resection from 1980 through 2006 to identify predictors of postoperative morbidity. Patients were divided into groups with or without chronic obstructive lung disease (COPD), defined as a ratio of forced expiratory volume in the first second to forced vital capacity of less than 0.7 or a ratio of 0.7 or greater, respectively. Analyses for each group identified covariates for three outcomes: operative mortality, pulmonary morbidity, and overall morbidity. Results: Of 1,046 patients in the database, 1,008 (545 men; mean age, 61.8 +/- 0.35 years) had data permitting determination of COPD status: 450 (45%) with COPD, 558 (55%) without COPD. Operations included lobectomy (752; 75%), bilobectomy (83; 8%), and pneumonectomy (173; 17%). Overall mortality, pulmonary morbidity, and overall morbidity incidences were 59 (5.8%), 140 (14.0%), and 311 (31.4%), respectively. Pulmonary morbidity and operative mortality were related to postoperative predicted Dlco, age, and performance status in patients with and without COPD. The postoperative predicted Dlco was the single strongest predictor of pulmonary morbidity and operative mortality in both patient groups. Overall complications were related to postoperative predicted Dlco only in the COPD group. Conclusions: Diffusing capacity is an important predictor of postoperative morbidity after lung resection even in patients with normal spirometry. Routine measurement of Dlco, regardless of spirometric findings, can help predict risk in candidates for major lung resection.

Sample Bronchoscopy Quiz QuestionThe attached pdf. shows a bronchoscopy photo question and answer similar to the those in the Bronchoscopy Quiz. Simply click on the Bronchoscopy Quiz button at the top of the home page to take the quiz. You will receive the number of answers you get correct after completing the 16 question Quiz. After you take the Bronchoscopy Quiz you have access to the bronchoscopy Simulator. We ask that you take the Bronchoscopy Quiz again after using the simulator and becoming familiar with fiberoptic tracheo-bronchial anatomy. After you take the quiz a second time you will receive the correct answers and you can compare anonymously the number you get correct with others who have taken the test. All results are confidential. Try it its fun and educational!