Page 1574 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 115: The Transplant Patient 1093

■ TRANSPLANT PROCEDURE venous pressure and outcome following transplant demonstrated a sig-

Since the first human lung transplant in the early 1980s, there has nificant improvement in duration of mechanical ventilation and survival
been considerable modification and refinement to the procedure. En in the population of patients who had central venous pressures main-
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bloc double lung transplant, which required cardiopulmonary bypass tained below 7 mm Hg following transplant. Whether this association
(CPB) and cardioplegia, has been replaced by bilateral sequential lung was causal needs to be validated in a prospective trial.
transplant with CPB limited largely to the pulmonary hypertension Chest Tubes: Chest tubes often remain in situ until air leaks have
population. Both lungs are initially freed from the pleural space, the pul- resolved and the patient has been extubated. Basal chest tubes may
monary arteries and veins are dissected and the bronchus is exposed at remain until postoperative days 5 to 7 given the high incidence of pleu-
the hilum. The lung with lesser physiologic contribution, based on pre- ral effusions that could affect lung compliance. It is suggested that they
operative ventilation perfusion scans, is transplanted first as the other are removed when draining less than 150 cc/24 hours. 43
lung will more likely support single lung ventilation and avoid the need
for CPB. End-to-end bronchial anastomosis is completed first followed Bronchoscopy: A series of surveillance bronchoscopies are carried out
by arterial and then venous anastomoses. The pulmonary arteries are in the first 2 years posttransplant. At our center, the first routine sur-
trimmed in size to avoid unnecessary kinking and then anastomosed. veillance bronchoscopy is performed at 2 weeks, preferably when the
The pulmonary veins (and corresponding preserved donor atrial attach- patient is extubated. Bronchoscopies prior to that period are generally
ment) undergo anastomosis with the left atrium of the recipient. After performed if clinically indicated.
the second lung is transplanted, controlled reperfusion with leukocyte Immunosuppression—Special Considerations for Lung Transplant: The
filtration is done slowly to minimize the incidence of primary graft mainstay of immunosuppressive management includes induction, main-
dysfunction. Minimization of intravenous fluids without compromising tenance, and antirejection therapy. The majority of transplant patients
end-organ perfusion has been used to reduce postoperative respiratory are maintained on lifelong immunosuppressive medications that are
insufficiency. The pleural spaces are drained with chest tubes and the typically comprised of triple therapy with a calcineurin inhibitor (CNI),
chest, muscle, and skin are closed. A flexible bronchoscopy is performed an antiproliferative agent, and a corticosteroid. In a meta-analysis
at the end of the transplant after exchanging the double lumen tube for a of cyclosporine and tacrolimus, mortality at 1 year was comparable
single lumen tube and the airway anastomoses are inspected. between the two medications, with the tacrolimus group experiencing
Cardiopulmonary bypass may be indicated in patients with either
isolated or coexisting pulmonary hypertension in the setting of ILD fewer incidences of acute rejection, a trend toward lower chronic rejec-
tion, but a higher rate of diabetes. Both groups had an equal incidence
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or COPD. These patients often have marginalized right ventricles that of hypertension, renal dysfunction, and infection.
cannot withstand increases in pulmonary artery pressures that they are Azathioprine and mycophenolate mofetil (MMF) are the most
subjected to during the single lung ventilation. Unfortunately, conven- common antiproliferatives used in lung transplantation. Based on data
tional CPB increases the risk of bleeding, primary graft dysfunction and from other organ transplants, there is a suggestion that mammalian tar-
creates a more pronounced systemic inflammatory response syndrome get of rapamycin inhibitors (mTOR) such as sirolimus and everolimus
(SIRS) postoperatively. The perioperative use of extracorporeal life could result in less chronic rejection; however, large-scale studies in the
support (ECLS) during double lung transplant has been explored with lung transplant populations are pending. Sirolimus is associated with
benefits being reported in a few small trials reporting lower incidents of airway dehiscence and therefore is not recommended in the early post-
ischemia reperfusion injury, anticoagulation, and SIRs. 40 transplant management. 45
■ POSTOPERATIVE MANAGEMENT Corticosteroids remain the mainstay of immunosuppressive therapy.

Ventilation: The early postoperative period may be characterized by They are initiated in all lung transplant patients. While heart and liver
transplant patients undergo aggressive steroid withdrawal within the
an ischemia reperfusion injury in the lungs—known as primary graft first year, this has not been attempted in the lung transplant population
dysfunction (PGD) (see “Postoperative Complications”). As a form of given the dramatic consequences of graft loss.
acute lung injury, many of the approaches that have been used to mini- Induction therapy use has increased to 62% in recent years; however,
mize lung injury and support gas exchange have been applied to PGD; there remains no consensus about choice of agents. At present, polyclonal
however, few have been systematically evaluated. A lung-protective and monoclonal anti-T cell antibodies are used as induction agents
ventilator strategy (see Chaps. 51 and 52) is recommended in the post- and exert their effect by cytoreducing alloreactive T cells during a time
operative period to minimize ventilator-induced lung injury. Often these when there exists a high donor leukocyte load (in the immediate post-
patients have a pulmonary artery catheter to assist in following their transplant period). The two preparations of polyclonal antibodies that
46
pulmonary artery pressures in the setting of worsening hypoxia. Most exist are equine antithymocyte globulin (ATG) and rabbit-derived ATG.
patients can be weaned from mechanical ventilation rapidly. High airway Muromonab cd-2 (OKT3) is the only monoclonal antibody currently
pressures should be avoided as this leads to compression of collateral flow available. The clinical utility of these agents is limited by the occasional
that the new lung depends on to perfuse the bronchial anastomosis. Some development of cytokine release syndromes. Preliminary studies evaluat-
centers are adopting noninvasive positive pressure ventilation (NIPPV) ing the use of induction therapy have shown an improvement in 14-day
as an option to shorten weaning time and to help minimize the risk of survival. Approximately one half of transplant centers use some form
31
developing ventilator-associated pneumonia. Rapid extubation followed of induction therapy. However, their long-term use is limited by the
by prompt NIPPV may become a useful strategy in those who do not development of neutralizing antibodies. Induction therapy with IL-2R
completely fulfill criteria for safe extubation. 41 antagonists (daclizumab and basiliximab) is gaining popularity and has
been shown to be associated with further reduced rates of acute rejection
Fluid Management: Many risk factors can precipitate SIRS in these 31
patients including cardiopulmonary bypass, primary graft dysfunction, compared to no induction or the use of polyclonal agents.
Table 115-4 summarizes routine postoperative management of the
and sepsis. As a result, these patients may succumb to noncardiogenic
pulmonary edema from profound capillary leak. The new transplanted lung transplant patient.
phatic drainage at the time of transplant. It is necessary, therefore, to ■ POSTOPERATIVE COMPLICATIONS
lungs have an impaired ability to clear edema given their severed lym-
avoid substantial transplant lung edema by minimizing fluid and blood Reducing complications within the first-year posttransplantation has
products wherever possible. While recognizing the inherent limitations had a significant impact on long-term survival. Multiple complications
associated with studies of fluid balances in the intensive care unit, a exist in the immediate posttransplant period that can lead to signifi-
retrospective review that evaluated the associations between central cant long-term morbidity and mortality. As a result, knowledge of the

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