Interact CardioVasc Thorac Surg 2008;7:755-758. doi:10.1510/icvts.2008.182881
© 2008 European Association of Cardio-Thoracic Surgery
Work in progress report - Transplantation |
Early tracheal extubation in adults undergoing single-lung transplantation for chronic obstructive pulmonary disease: pilot evaluation of perioperative outcome
John G. Augoustidesa,*,
Sam M. Watchaa,
Alberto Pochettinob and
David R. Jobesc
a Anesthesiology and Critical Care, 680 Dulles Building, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA
b Cardiothoracic Surgery and Surgical Director of Lung Transplantation, USA
c Anesthesiology and Critical Care, Hospital of the University of Pennsylvania, USA
Received 29 April 2008;
received in revised form 24 June 2008;
accepted 30 June 2008
*Corresponding author. Tel.: +1 (215) 662-7631; fax: +1 (215) 349-8133.
E-mail address: yiandoc{at}hotmail.com (J.G. Augoustides).
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Abstract
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The objective of this pilot study was to evaluate the safety and success of early tracheal extubation (ETE) as compared to delayed tracheal extubation (DTE) in single-lung transplantation (SLT) for chronic obstructive pulmonary disease (COPD). This retrospective observational study was undertaken at a university hospital. Fifty-seven adult patients who underwent SLT for COPD (1998–2003) were enrolled. The study cohort was divided into an ETE subgroup (tracheal extubation in the operating room) or a DTE subgroup (tracheal extubation in the intensive care unit). There were no significant differences in perioperative outcomes between subgroups (in-hospital mortality; length of stay; prolonged mechanical ventilation; primary graft dysfunction; pneumonia; atrial fibrillation; renal dysfunction; and, sepsis). The anesthetic technique associated with ETE in SLT for COPD was characterized by limited systemic anesthetics and perioperative thoracic epidural analgesia. Appropriate ETE in SLT for COPD is not only safe but also results in equivalent perioperative outcome when compared to the traditional technique of DTE. Future studies should be powered to examine whether ETE reduces native lung complications such as hyperinflation, pneumonia and pneumothorax.
Key Words: Lung transplantation; Perioperative outcomes; Chronic obstructive pulmonary disease; Early tracheal extubation
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1. Introduction
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Single-lung transplantation (SLT) is currently more common than bilateral lung transplantation for chronic obstructive pulmonary disease (COPD), despite the risks of complications such as hyperinflation, pneumonia, pneumothorax, opportunistic infections and lung cancer [1]. Bilateral lung transplantation may become more common in COPD, given the documented overall survival benefit, including in the presence of bronchiolitis obliterans [1].
Although native lung hyperinflation after SLT for COPD is surgically correctable, the possible benefit of early tracheal extubation (ETE) after SLT for COPD to minimize compliance mismatch and hyperinflation has recently been highlighted [2, 3]. The potential benefits of ETE in this setting prompted a gradual shift in perioperative practice at our institution from 1998 onwards. In this article, we report our five-year experience with ETE after SLT for COPD. The hypothesis of this pilot project was that ETE for SLT in COPD does not worsen perioperative outcome as compared to delayed tracheal extubation (DTE) in the intensive care unit (ICU).
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2. Methods
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2.1. Data collection and analysis
With institutional review board approval, a retrospective chart review was performed for adults with COPD who underwent SLT between 1998 and 2003 (n=57). The patient cohort was divided into two subgroups depending on the timing of tracheal extubation: ETE was defined as tracheal extubation in the operating room prior to intensive care unit (ICU) admission (group A); DTE was defined as tracheal extubation after ICU admission (group B). Since this study was retrospective, patients were not randomized to ETE or DTE during the conduct of SLT. The timing of tracheal extubation after SLT was at the discretion of the attending cardiothoracic anesthesiologist after discussion with the attending cardiothoracic surgeon. Thus, the study subgroups have selection bias.
Experienced research assistants abstracted the retrieved medical records in an electronic database (Microsoft Access, Microsoft, Seattle, Washington). Data analysis was performed with standard statistical software (Stata 8.0, StataCorp LP, College Station, Texas, USA). Student's t-test was used for normally distributed data and Wilcoxon's ranked sum test for nonnormally distributed data. The  2-test or Fisher's exact test, as appropriate, was performed for categorical variables. Statistical significance was set at a probability value, P 0.05.
2.2. Outcome definitions
Length of stay in the ICU was defined as the total number of ICU days. Length of hospital stay was defined as the total number of hospital days, including ICU stay. Duration of mechanical ventilation was defined as the total number of hours with mechanical ventilatory support via an endotracheal tube. Transfusion was defined as the total number of blood components administered (in blood bank units). Sepsis was defined according to international guidelines as a systemic inflammatory response with a presumed or known site of infection [4]. A systemic inflammatory response was diagnosed by the presence of at least two of the following: body temperature alterations (hyperthermia or hypothermia); tachycardia; tachypnea; and, changes in the white blood cell count (leukocytosis or leukopenia). Pneumonia was defined as lung infection as evidenced by at least two of the following: systemic inflammatory response; chest radiograph showing alveolar infiltrative pattern compatible with pneumonia, as interpreted by an attending radiologist; and, positive sputum cultures. Severe primary graft dysfunction was defined as diffuse alveolar pulmonary infiltrates accompanied by an arterial partial pressure of oxygen/fraction of inspired oxygen <200 and no identified secondary cause of lung dysfunction (ISHLT Grade III) [5]. All patients were seen daily by a pulmonologist dedicated to SLT. Renal dysfunction was defined as a >50% increase in baseline creatinine.
2.3. Lung transplant protocol
All patients underwent comprehensive preoperative evaluation by the multidisciplinary lung transplant team. In the operating room, a midthoracic epidural was placed with the patient in the sitting position after intravenous access was established. The timing of thoracic epidural placement was at the discretion of the attending anesthesiologist. Besides routine monitors as per the American Society of Anesthesiologists, invasive monitoring consisted of a radial arterial catheter, and an oximetric pulmonary arterial catheter. General anesthesia was via a balanced technique consisting of titrated fentanyl, midazolam and isoflurane-in-oxygen. Selective lung ventilation was achieved with an appropriately sized left-sided double lumen endotracheal tube, positioned under bronchoscopic guidance. Antibiotic coverage was broad spectrum, tailored to donor and recipient cultures. Immunosuppression was standardized and multimodal (methylprednisolone; mycophenolate; tacrolimus). Indications for cardiopulmonary bypass (CPB) included severe hypoxemia or right ventricular failure during single-lung ventilation. Inhaled prostacyclin I2 (Flolan, Glaxo Smith Kline, Philadelphia, PA: from 2001 onwards) or inhaled nitric oxide (INOmax, INO Therapeutics, Clinton, NJ: 1998–2000) was administered for management of pulmonary hypertension and/or modulation of the ischemia-reperfusion injury [6]. Both these selective pulmonary vasodilators were routinely utilized during SLT for COPD. The typical dosage ranges for inhaled nitric oxide and inhaled prostacyclin I2 were (20–40) parts per million and 25–50 ng/kg/min, respectively.
After thoracotomy, dissection and pneumonectomy, the pulmonary graft was implanted as follows: the bronchial anastomosis was performed first and then tested for air leaks with 30–35 cm H2O positive-pressure; the pulmonary venous anastomosis to the left atrium was performed second; the pulmonary arterial anastomosis was performed last. The lung was thoroughly deaired before vascular unclamping to avoid systemic embolism. Just prior to graft reperfusion, 500 mg of methylprednisolone was administered intravenously.
When required, CPB was instituted via standardized aortic and atrial cannulation. Anticoagulation was achieved with bolus heparin to maintain the activated clotting time of 400 s and CPB flows were maintained for a cardiac index of two liters per minute per square meter. During CPB an arterial blood gas (including hematocrit and glucose) was checked every 30 min. Packed red blood cell transfusion was titrated to maintain an average hematocrit of (23–25%). Isoflurane (0.5–1.0%) was administered continuously during CPB. Tracheal extubation criteria were standardized, regardless of extubation strategy. Postoperative management in the cardiothoracic intensive care unit was coordinated by a dedicated intensivist.
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3. Results
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Of the 57 patients studied, 21/57 (36.8%) underwent ETE (Group A) and 36/57 (63.2%) underwent DTE (Group B) in the ICU. Cohort subgroups were equivalent except for a significantly higher male gender and body surface area in group A (Table 1; P<0.05). As shown in Table 2, group A received significantly less intravenous anesthesia and neuromuscular blockade and had a significantly higher exposure to intraoperative thoracic epidural analgesia. Group A also were significantly more likely to undergo left-sided transplantation. Major perioperative outcomes were equivalent between groups (Table 3). As expected, duration of tracheal intubation was significantly shorter in group A, with a trend to a higher rate of repeat tracheal intubation (Table 4; P=0.09). All study patients required supplemental oxygen at the time of ICU admission, regardless of subgroup. The remaining respiratory outcomes were equivalent between subgroups.
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4. Discussion
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To the best of our knowledge, this is the first study to evaluate ETE in a cohort who all underwent SLT for COPD. The data from this pilot study show that ETE in this setting is as safe as DTE in the ICU. Since ETE has demonstrated safety and perioperative equivalency, the second question now becomes relevant: does ETE improve perioperative outcome after SLT for COPD? The answer to this question is the focus of our continuing research in SLT for COPD. This first study was undertaken to assess the strong clinical impression that ETE was not inferior to DTE in the perioperative management of this patient group.
The data from our pilot study also describe components of the anesthetic technique that are significantly associated with successful ETE after SLT for COPD, namely limited systemic anesthetics including narcotics, perioperative thoracic epidural analgesia and titrated facemask oxygen therapy. These components of an anesthetic technique for safe and successful ETE in LT are in agreement with published results from Sweden, Italy and Denmark [7–9].
The limitations of this pilot study include the following: (1) it is retrospective; (2) it is a single-center experience five years after the introduction of deliberate ETE after SLT for COPD; (3) the sample size is too small to assess whether ETE improves outcome after SLT for COPD; and (4) there is significant selection bias in the study cohorts since the timing of tracheal extubation after SLT was at the discretion of the attending cardiothoracic anesthesiologist after discussion with the attending cardiothoracic surgeon.
In conclusion, ETE appears safe and equivalent to DTE after SLT for COPD as evidenced by equivalent perioperative outcomes. The anesthetic technique for ETE should include limited systemic anesthetic, limited neuromuscular blockade, thoracic epidural analgesia and titrated supplementary noninvasive oxygen therapy. Future studies should focus on whether ETE and hence shorter duration of mechanical ventilation offer an outcome advantage after SLT for COPD. Potential outcomes that may be improved include native lung hyperinflation, ventilator-associated pneumonia and pneumothorax [10, 11].
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References
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Abstract
1. Introduction