Perioperative anaesthetic considerations for patients undergoing lung transplantation

Pre-anaesthetic evaluation of the patient with end-stage lung disease

Lung transplantation is a viable alternative for end-stage lung diseases, which offers good quality of life and survival outcomes for recipients. The aims of pre-assessment for potential lung transplant recipients are to assess fitness for surgery, optimise co-morbidities, commence interventions or investigations, weigh risk-benefit ratio, plan appropriate analgesia and obtain informed consent. The assessment information is gathered from the medical record, patient interview, physical examination and pre-operative tests. A comprehensive workup includes cardiopulmonary evaluation, haematological, biochemical, microbiological and immunological investigations. Most of the evidence regarding lung transplantation is gleaned from retrospective data from single, multi-centre or multinational registries. The lack of good quality evidence means that the guidelines are based on expert consensus.

Anesthesia for Lung Transplantation

Lung transplantation is the only therapeutic option for more than 3,000 individuals in the United States with end-stage lung disease. Innovations in anesthetic and surgical techniques have expanded the indications for lung transplantation. Presently, the major limiting factor in the number of lung transplantations that are performed is the availability of suitable donor organs. Lung transplantation includes a number of surgical procedures, including single-lung, double-lung, bilateral-sequential-single-lung, heart-lung, and lobar transplantation. Patients undergoing lung transplantation present a variety of challenges to the anesthesia team. Critical periods include induction of anesthesia, initiation of positive pressure ventilation, establishment and maintenance of one-lung ventilation, pulmonary artery clamping, pulmonary artery unclamping, and reperfusion of the transplanted lung. Pharmacologic advances have been an important factor in the continued development and success of lung transplantation. Newer immunosuppressive agents have improved the prevention and management of post-transplant rejection. Selective pulmonary vasodilators that are administered via inhalation affect the anesthetic management during the surgical procedure. Technologic advances in monitoring have also been valuable in lung transplantation. Transesophageal echocardiography is commonly used to evaluate intraoperative ventricular function. Continuous cardiac output, mixed venous oxygen saturation, continuous arterial blood gas monitoring, and the bispectral index have also been used to monitor the patient during lung transplantation. Anesthetic management of lung transplantation requires a thorough understanding of end-stage lung disease and pharmacologic and technical considerations that may not be applicable in any other part of anesthetic practice.

Common Pitfalls in Anesthesia for Noncardiac Thoracic Surgery

Over the past few decades, major surgical procedures involving the thorax have become commonplace at most larger medical facilities. Advances in perioperative care have allowed surgeons to perform increasingly complex procedures. These procedures are being performed on more seriously ill patients who are at increased risk for significant complications. Recent advances should help the anesthesiologist avoid some of the pitfalls in managing these complex patients. Preoperative assessment aids in the identification of patients at highest risk for intraoperative and postoperative events. Particular attention is given to myasthenia gravis, as thymectomy is among the most common surgical procedures that are performed in these patients. Aggressive pain control techniques, including neuraxial opioids and patient-controlled analgesia, where appropriate, not only improve patient comfort but can improve postoperative pulmonary function. Advances in techniques for providing one-lung ventilation allow the anesthesiologist more options to individualize management for each clinical scenario. Careful fluid management may help to minimize the risk of postoperative pulmonary complications. A basic understanding of video-assisted thoracic surgery should help the anesthesiologist provide optimal surgical conditions and perioperative care. Recent advances demand a greater role for the anesthesiologist if the best outcomes are to be achieved in patients undergoing thoracic procedures.

MECHANICAL VENTILATION FOR THE LUNG TRANSPLANT RECIPIENT

Mechanical ventilation (MV) is an important aspect in the intraoperative and early postoperative management of lung transplant (LTx)-recipients. There are no randomized-controlled trials of LTx-recipient MV strategies; however there are LTx center experiences and international survey studies reported. The main early complication of LTx is primary graft dysfunction (PGD), which is similar to the adult respiratory distress syndrome (ARDS). We aim to summarize information pertinent to LTx-MV, as well as PGD, ARDS, and intraoperative MV and to synthesize these available data into recommendations. Based on the available evidence, we recommend lung-protective MV with low-tidal-volumes (≤6 mL/kg predicted body weight [PBW]) and positive end-expiratory pressure for the LTx-recipient. In our opinion, the MV strategy should be based on donor characteristics (donor PBW as a parameter of actual allograft size), rather than based on recipient characteristics; however this donor-characteristics-based protective MV is based on indirect evidence and requires validation in prospective clinical studies.

Transesophageal Echocardiography During Lung Transplantation

Transesophageal echocardiography (TEE) is a semi-invasive monitoring technique increasingly used in cardiac surgery and in major noncardiac surgery for patients with known or supposed cardiac or coronary problems. During lung transplantation (LTx), the close interrelation between heart and lung function makes TEE an invaluable tool for instantly monitoring the physiopathological situation in the subsequent steps of the intervention. In patients scheduled for LTx, induction of anesthesia could be a dangerous moment with the possibility of cardiogenic shock if pulmonary hypertension (PH) exists; pneumatic tamponade is also possible in patients with emphysema caused by alpha(1)-antitrypsin deficiency, with subsequent cardiac insufficiency. One-lung ventilation is a critical phase during LTx; hypoxemia resulting from ventilation of a diseased dependent lung could impair heart oxygenation, particularly if tachycardia is present. Clamping of the pulmonary artery before pneumonectomy could exacerbate cardiac afterload, especially in patients with previous PH. High transmural pressure, linked with low systemic pressure, makes right ventricle (RV) perfusion pressure inadequate. Hypoxemia and PH are the most frequent causes of intraoperative RV decompensation. In this special setting, TEE is irreplaceable in informing the anesthesiologist about the correct time for extracorporeal oxygenation. Lung reperfusion brings with it the possibility of coronary gaseous embolism, easily detected with TEE. After LTx, TEE can be used to detect strictures, thrombi, or permeability of pulmonary venous anastomoses. To summarize, intraoperative TEE during LTx contributes to the immediate recognition of critical events and allows for rapid therapeutic interventions.

Anesthetic Concerns in Lung Transplantation for Severe Pulmonary Hypertension

Lung transplantation has become a consolidated treatment for patients with severe pulmonary hypertension (PH). Several difficulties are encountered during the procedure in such candidates, who are still recognized as more severely affected by perioperative morbility and mortality than those undergoing lung transplantation for other diseases. Right ventricular (RV) enlargement with tricuspid regurgitation, small left ventricle (LV) with an asymmetric hypetrophic wall, interventricular septal shift toward the left, with ventricular stiffness and diastolic incompetence, are typical preoperative echocardiographic findings of end-stage PH. A smooth induction and tracheal intubation will help prevent hypertensive crisis in highly susceptible candidates. Uncompensated vasodilatation or myocardial depression caused by anesthetics and mechanical ventilation may be responsible for acute RV dysfunction associated with low systemic blood pressure. Resuscitation and emergency adoption of cardiopulmonary by-pass (CPB) has been described for near-fatal anesthesia induction. Cardiovascular instability can develop after institution of one-lung ventilation and pulmonary artery clamping. An acute increase in pulmonary pressure results in a decrease in RV ejection fraction and then in acute RV failure. Interdependence of the right and left ventricles occurs such that RV function can alter LV function. Early detection of impending circulatory and/or respiratory deterioration is warranted to prevent an irreversible decline in cardiac output, resulting in hazardous cardiac arrest. Inhaled nitric oxide represents the first choice for treatment of PH and RV failure associated with systemic hypotension during lung transplantation. Intraoperative situations requiring CPB must be identified before development of systemic shock, which represents a late ominous sign of RV failure.

Anesthetic implications for lung transplantation

Anesthetic challenges regarding lung transplantation are related to the expanded spectrum of diseases for which lung transplantation is offered and to the interval changes in health status likely to occur as patients wait longer for an organ to become available. Particular attention to avoiding or reducing the impact of increases in pulmonary vascular resistance and right heart failure are important and may necessitate cardiopulmonary bypass. Intraoperative and postoperative ventilator management should account for differences in pulmonary compliance after the new lung is implanted. Minimizing intravenous fluids without compromising end organ perfusion may avoid or reduce postoperative respiratory insufficiency.

[Prognostic factors of early morbidity and mortality after lung transplantation]

OBJECTIVES

Despite years of experience with lung transplantation, the rate of perioperative mortality remains high. The objective of this study was to look at our experience in the early postoperative period following lung transplantation in an effort to identify possible pre-, intra- and postoperative risk factors associated with mortality.

PATIENTS AND METHODS

A retrospective study of 68 consecutive patients receiving lung transplants over a period of 56 months. The conditions that led to transplantation were obstructive disease (40%), interstitial disease (33%) and suppurative disease (27%). Pre-, intra- and postoperative characteristics of donors and recipients were analyzed for their relation to morbidity and mortality. Statistical studies were done using SPSS 10.0 software. A p-value less than.05 was considered significant. Univariate analysis identified variables associated with the incidence of mortality in the postoperative recovery unit, and the variables with statistically significant associations were entered into multivariate analysis, using a logistic regression model to calculate odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

No donor variables correlated with mortality. Patients with suppurative lung disease had a lower mortality rate (0% vs 30%; P = 0.04). Mortality was related to ischemic time longer than 300 minutes (OR = 2) and the use of extracorporeal circulation (OR = 4). A PaO2/FiO2 ratio less than 150 during the first 24 hours following transplantation (OR = 5) and reoperation due to bleeding (OR = 12) were the variables showing the highest correlations with mortality during the early postoperative period.

CONCLUSIONS

The mortality rate during the early postoperative period in our series was 22%. The survival rate was better in patients with suppurative lung disease. Bleeding that required reoperation and early graft dysfunction (defined in part by a PaO2/FiO2 ratio less than 150 during the first 24 hours) were the variables that best predicted death in the early postoperative period following lung transplantation.

Is very early extubation after lung transplantation feasible?

OBJECTIVE

To evaluate donor graft function, intraoperative blood consumption, and oxygenation and hemodynamic stability in patients undergoing lung transplantation.

DESIGN

Prospective pilot study.

SETTING

University hospital.

PARTICIPANTS

Forty-three patients undergoing lung transplantation from January 1999 to June 2001.

INTERVENTIONS

Hemodynamic monitoring, early extubation, and noninvasive ventilation criteria.

MEASUREMENTS AND MAIN RESULTS

The 31 nonearly extubated patients showed a lower PaO(2)/fraction of inspired oxygen (F(I)O(2)), a higher mean pulmonary arterial pressure, extravascular lung-water index (EVLWI) and vasoactive drug support (norepinephrine), and more blood products consumption than 12 early extubated patients at the end of surgery. Seven of 12 early extubated patients did not show any signs of respiratory failure after tracheal extubation; they were alert and able to perform deep breathing exercise and coughing. In the other 5 patients, hypoxemia, hypercapnia, and an increase of respiratory rate >30 breaths/min were observed. The intermittent application of noninvasive pressure ventilation by face mask avoided endotracheal intubation.

CONCLUSION

The use of a short-acting anesthetic drug, appropriate intraoperative extubation criteria, epidural analgesia, and postoperative noninvasive ventilation make early extubation of lung-transplanted patients possible and effective.

Preload indexes in thoracic anesthesia

PURPOSE OF THE REVIEW

An adequate cardiac preload is essential in the treatment of critically ill patients. During anesthesia for thoracic surgery, volume and vasoactive therapy to optimize cardiac output, oxygen delivery (tissue perfusion) and to avoid pulmonary edema is a central therapeutic aspect. Cardiac preload has been estimated with different techniques in clinical practice, even though studies performed on thoracic anesthesia are lacking.

RECENT FINDINGS

We analyze the conventional pulmonary artery catheter, transesophageal echocardiography and the transpulmonary indicator dilution technique as preload monitoring devices with their indications and limits in thoracic anesthesia.

SUMMARY

The pulmonary artery catheter is confirmed as a fundamental device particularly in patients with pulmonary hypertension. For transesophageal echocardiography monitoring, the dependency on operator experience, the low repeatability and the high costs limit its interpretation and diffusion in clinical practice. During lung transplantation, Swan Ganz catheter monitoring is recommended. The optimization of fluid balance and vasoactive drug administration based on volumetric monitoring makes the transpulmonary indicator dilution technique a new option as an effective monitoring system during anesthesia for thoracic surgery when intravascular volume management is a primary objective.

Preload index: pulmonary artery occlusion pressure versus intrathoracic blood volume monitoring during lung transplantation

In this study, during lung transplantation, we analyzed a conventional preload index, the pulmonary artery occlusion pressure (PAOP), and a new preload index, the intrathoracic blood volume index (ITBVI), derived from the single-indicator transpulmonary dilution technique (PiCCO System), with respect to stroke volume index (SVIpa). We also evaluated the relationships between changes (Delta) in ITBVI and PAOP and DeltaSVIpa during lung transplantation. The reproducibility and precision of all cardiac index measurements obtained with the transpulmonary single-indicator dilution technique (CIart) and with the pulmonary artery thermodilution technique (CIpa) were also determined. Measurements were made in 50 patients monitored with a pulmonary artery catheter and with a PiCCO System at six stages throughout the study. Changes in the variables were calculated by subtracting the first from the second measurement (Delta(1)) and so on (Delta(1) to Delta(5)). The linear correlation between ITBVI and SVIpa was significant (r(2)=0.41; P < 0.0001), whereas PAOP poorly correlated with SVIpa (r(2) = -0.01). Changes in ITBVI correlated with changes in SVIpa (Delta(1), r(2) = 0.30; Delta(2), r(2) = 0.57; Delta(4), r(2) = 0.26; and Delta(5), r(2) = 0.67), whereas PAOP failed. The mean bias between CIart and CIpa was 0.15 l. min(-1). m(-2) (1.37). In conclusion, ITBVI is a valid indicator of cardiac preload and may be superior to PAOP in patients undergoing lung transplantation.

IMPLICATIONS

The assessment of intrathoracic blood volume index (ITBVI) by the transpulmonary single-indicator technique is a useful tool in lung transplant patients, providing a valid index of cardiac preload that may be superior to pulmonary artery occlusion pressure. However, more prospective, randomized studies are necessary to evaluate the role and limitations of this technique.

Hemodynamic and oxygenation changes of combined therapy with inhaled nitric oxide and inhaled aerosolized prostacyclin

OBJECTIVE

To evaluate hemodynamic and oxygenation changes of combined therapy with inhaled nitric oxide (iNO) and inhaled aerosolized prostcyclin (IAP) during lung transplantation.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Ten patients scheduled for lung transplantation.

INTERVENTIONS

Ten patients, with a mean age of 38 years (range, 24 to 56 years), were scheduled for lung transplantation (2 single-lung transplantations and 8 double-lung transplantations). During first lung implantation with single-lung perfusion and ventilation, hemodynamic and oxygenation data were analyzed in 3 phases: (1) baseline, 5 minutes after pulmonary artery clamping; (2) inhaled NO phase, 15 minutes after inhaled NO administration (20 ppm) in 100% oxygen; and (3) IAP-inhaled NO phase, 15 minutes after combined administration of inhaled NO (20 ppm) and IAP (10 ng/kg/min) in 100% oxygen.

MEASUREMENTS AND MAIN RESULTS

During the inhaled NO phase, reductions of mean pulmonary arterial pressure (p < 0.05) and intrapulmonary shunt (p < 0.05) were noted. After the start of prostacyclin inhalation, a further decrease in mean pulmonary arterial pressure (p < 0.05) was observed. PaO2/FIO2 increased during the IAP-inhaled NO phase (p < 0.05), whereas intrapulmonary shunt decreased (p < 0.05).

CONCLUSION

This study confirms the action of inhaled NO as a selective pulmonary vasodilator during lung transplantation. Combined therapy with IAP and inhaled NO increases the effects on pulmonary arterial pressure and oxygenation compared with inhaled NO administered alone without any systemic changes.

Skin sympathetic neuroeffector response is attenuated dose-dependently by systemic prostaglandin E1 injection in humans

To clarify the effects of prostaglandin E1 (PGE1) on the vasoconstrictive responses, we compared the correlation between the amplitude of integrated skin sympathetic nerve activity (SSNA) and per cent reduction in skin blood flow (SBF) before and after the infusion of lipo PGE1 and placebo (bolus one-shot infusion, single blind study), and constant rate infusion of PGE1 (10 and 50 ng kg(-1) min(-1) by infusion pump, dose-dependency study) in ten healthy men. SSNA was recorded microneurographically from the median nerve simultaneously with SBF by laser Doppler flowmetry at the index fingertip. The measurement was conducted 30 min after injection of lipo PGE1 or placebo, and during the drip infusion of 10 and 50 ng kg(-1) min(-1) of PGE1 with maneuvers to enhance SSNA. The resting and activated skin blood flow were not significantly different between 10 ng lipo PGE1 and placebo administration, and between baseline and 10, 50 ng kg(-1) min(-1) of PGE1 injection. The vascular response, defined as the slope of regression line between logarithm of amplitude of integrated SSNA bursts and the reduction in SBF, was significantly suppressed by injection of lipo PGE1 as compared with that by placebo. It was also decreased dose-dependently by the constant rate infusion of PGE1 (10 and 50 ng kg(-1) min(-1)). We concluded that the intravenous injection of PGE1 attenuates vasoconstrictive responses to SSNA, and analysis of the relations between SSNA and vasoconstrictive response, i.e. the neuroeffector response, is suggested to be an important tool to assess the drug effect.

Anaesthesia for patients with a transplanted organ

Increasing numbers of individuals leading normal lives have transplanted organs. They may appear in any hospital for treatment of trauma or general diseases. Common anaesthesia methods can be used for these patients, but safe conduct of anaesthesia requires knowledge of the immunosuppression, risk factors, and altered physiology or drug actions. This article reviews the anaesthesia-related literature on patients with transplanted organs.

Pulmonary transplantation

Anesthetic technique for pulmonary transplantation varies with recipient's underlying lung disease, procedure performed and regional practice. The pulmonary allograft is vulnerable to mechanical and biochemical injury throughout the harvesting, preservation and engraftment procedures. Mechanisms of allograft injury are reviewed, with suggestions for incorporation of strategies to minimize injury into clinical practice. Particular emphasis is placed on the use of nitric oxide for treatment of reperfusion injury.

Perioperative management of patients undergoing lung transplantation

This review focuses on recent developments in the perioperative management of patients undergoing lung transplantation. Relevant current literature and the experience of the Munich Lung Transplant Group were taken into consideration. Recent advances include the use of inhalational nitric oxide for the treatment of early graft dysfunction and the use of aerosolized cyclosporine for the treatment of recurrent and steroid-resistant acute rejection. Opportunistic infections remain a major source of morbidity and mortality in lung transplant recipients.