Central nervous system infectious complications early after liver transplantation.

Infectious complications contribute to significant patient morbidity and mortality in orthotopic liver transplant (OLT) recipients. Early central nervous system (CNS) involvement (within the first month after OLT) by infectious disease is essentially set off by aggressive surgical procedures, severe morbid conditions of the pretransplant period, initial graft dysfunction, permanence of intravascular catheters, and prolonged mechanical ventilation. The type and severity of CNS infection may be determined by many factors, such as posttransplant adverse events; prolonged or repeated surgery with massive intraoperative transfusions, net state of immunosuppression, recurrence of infections by immunomodulating viruses, and retransplantation. Bacteria, viruses, and fungi can spread to the CNS just as they affect the abdomen, blood stream, respiratory tract, urine, drainages, etc. Because immunosuppressive drugs may modify the clinical presentation of CNS infections, it is very important to maintain vigilance and attend to minor neurologic symptoms. Special attention should therefore be given to cerebral investigation in patients with prolonged pulmonary contamination, unresponsive fever, and heavy corticosteroid therapy, primarily when they became disoriented, develop seizures, or exhibit focal neurologic signs. Clinical response to medical therapy may sometimes be poor because of chronic encapsulation of the pathogen, development of resistance, and/or catastrophic hemorrhagic complications.

Hemodynamic profile of portopulmonary hypertension.

Portopulmonary hypertension (PPHTN) refers to the development of pulmonary arterial hypertension in the setting of portal hypertension with or without chronic hepatic failure. This syndrome is characterized by marked alternations of pulmonary vascular tone and obstruction of pulmonary arterial blood flow. An increased pulmonary blood flow, which is a hallmark of the hyperdynamic circulation of cirrhotic patients, seems to be present in almost all patients who develop PPHTN. The elevations of pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) along with the transpulmonary gradient (TPG) have been considered in diagnosing PPHTN. Only a high TPG reflects the severity of obstruction to pulmonary blood flow and differentiates an elevated PAP with concomitant elevated PVR from the situation where the increase in PAP is due only to the hyperdynamic flow and elevated volume. A considerable risk for cardiovascular death arises when PAP increases significantly; this may occur in rapidly evolving syndromes, in very advanced disease, or during a complicated liver transplantation. The distinction between PPHTN and elevated PAP in the context of a hyperdynamic state is of great importance; a PAP increase of hyperkinetic origin, as opposed to PPHTN, is apparently not associated with a high risk for adverse effects during and following liver transplantation.

Noninvasive ventilation in adult liver transplantation.

Noninvasive ventilation (NIV) has proven to be a safe and effective technique in the treatment of respiratory failure complicating various medical and surgical diseases. In recent years, a growing interest has emerged in its adoption for ventilatory assistance in immunocompromised patients, such as those undergoing bone marrow, liver, lung, cardiac, and kidney transplantation. Weaning from the ventilator after liver transplantation can take longer because of unsatisfactory gas exchange during various attempts of T-piece trials. Rapid extubation followed by an immediate NIV application should be considered in this setting to shorten and accelerate the weaning process in those recipients who do not completely fulfill the criteria for safe extubation. By adding the pressure support (PS) mode with a continuous positive end expiratory pressure (PEEP), NIV could prevent the loss of vital capacity and impede severe lung derecruitment following extubation. Clinical experience has shown that properly delivered NIV mostly benefits moderately dyspneic recipients in acute respiratory failure, while it appears less promising and efficient in patients ventilated for extended periods of time. It has proven safe and efficient mainly as (1) a tool to promote an early ventilatory discontinuation and extubation; (2) a prophylactic strategy for preventing postoperative pulmonary complications; and (3) a simple method to start with in cases of acute hypoxic and/or hypercapnic respiratory failure. The improvements in arterial hypoxemia, the decreased ventilatory demand provided with an inspiratory support, as well as the scarcity of hemodynamic repercussions are among the major benefits of this method.

Microbiologic contamination of intraoperative blood salvaged during liver transplantation.

Bacterial contamination is one of the potential risks of blood salvage and reinfusion during orthotopic liver transplantation (OLT) because cell-saver machines lack antibacterial protection devices. This study was designed to analyze the potential bacterial contamination of blood salvaged during OLT; a secondary end point was to evaluate whether reinfusion of potentially contaminated blood may have been responsible for clinically manifested infective complications in the same patient. After induction of anesthesia, a blood sample was drawn from the central venous catheter (CVC) immediately after its positioning, to exclude potential coexisting hematic contamination of the recipient. During the procedure, 2 other samples of salvaged blood were collected for bacteriological analysis. Twenty-six of 38 samples of salvaged blood were positive for microorganisms, whereas 12 did not reveal the presence of infectious agents. In 19 of 26 positive samples, Staphylococcus species (73%) were isolated with only 2 of 38 samples drawn from CVC being contaminated. Candida Albicans was cultured in 2 samples. The high percentage (73%) of coagulase-negative Staphylococci indicates that blood contamination could have been caused by microorganisms from the air or suctioned from contact surfaces and the surgical field. Although almost 70% of processed and reinfused units tested positive for microbes, none of the postoperative blood cultures (at day 1 and day 3) revealed growth of the same species, not even in the 2 patients who had positive CVC cultures after induction of anesthesia.

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.

Cerebral blood flow in fulminant hepatitis.

Fulminant hepatic failure (FHF) is often complicated with cerebral edema, intracranial hypertension, and coma. Cytotoxic and vasogenic factors have been recognized in the etiology of cerebral edema. One of the main causes seems to be the accumulation of glutamine in astrocytes, which is produced from ammonia and the excitatory neurotransmitter glutamate. Ammonia is detoxified within the brain in astrocytes, where it increases the osmotic pressure for water. Ammonia-induced astrocytic water accumulation seems to act as an integrative trigger for the development of intracranial hypertension. While cerebral blood flow is sometimes reduced in the first stage of FHF, as compensatory cerebral vasoconstriction to reduce mean arterial pressure, it later increases as hyperammonemia decreases cerebral arteriolar tone. Despite vasodilation in the systemic and splanchnic beds at early stages of the disease, cerebral vessel resistance may increase, so that cerebral perfusion pressure may be preserved. When cerebral vascular tone is no longer effective in the course of illness, vasodilation gradually develops and rapidly becomes poorly responsive to carbon dioxide stimulation, which signifies loss of autoregulatory tone and cerebral hyperemia develops. Prolonged excessive flow may lead to brain swelling, vasogenic edema, and intracerebral hemorrhage. Brain edema further aggravates the critically reduced cerebral perfusion and is responsible for the high mortality.

[Prognostic systems in intensive care: TRISS, SAPS II, APACHE III]. / Scale prognostiche in terapia intensiva: TRISS, SAPS II, APACHE III.

BACKGROUND: To validate the accuracy of SAPS II, APACHE III and TRISS for the prediction of mortality in Intensive Care Unit (ICU) at polytrauma patients admission. The outcome of multiple trauma patients is often linked to the degree of physiologic dysfunction and to the extension of anatomic lesions, the age of the patient and the lesion mechanism. METHODS: The study population consisted of 93 cases of multiple injured patients hospitalised at the ICU of the Padua hospital from October 1998 to October 1999; the term polytraumatized patient is referred to patients who have multiple lesions of which at least one potentially endangers, immediately or in a short term, their life. These cases were evaluated with the APACHE III, SAPS II, Revised Trauma Score and Injury Severity Score. The predictive power of each system was evaluated by using decision matrix analysis to compare observed and predicted outcome with a decision criterion of 0.50 and 0.40 for risk of hospital death. RESULTS: All trauma score systems under study showed high accuracy rates, above all if they are used with a 40% positive test. CONCLUSIONS: The prognostic scales used in this study showed a good correlation between expected and observed cases, particularly with TRISS and APACHE III systems. The APACHE III system seems to be the most reliable of the different methods analysed. These prognostic systems are seldom or occasionally used in the ICU, in Padua and in the whole of Italy, so Italian data are not suitable to be compared to international ones. Due to urgency, the importance of the evaluation scales is often underestimated, but even if they require time and attention, they surely can be useful in the evaluation of the treatment, and not only of a polytraumatized patient.