Walter Plöchl

Nutritional status, ICU duration and ICU mortality in lung transplant recipients

ObjectiveTo determine the relation of malnutrition and underlying diagnosis to the length of stay in the Intensive Care Unit (ICU) and to mortality after lung transplantation (LTX).DesignRetrospective ICU chart review.SettingCardiothoracic ICU in a University hospital.PatientsFifty-one consecutive patients who suffered from end-stage lung disease from. April 1992 to January 1994.InterventionsNone.Measurements and resultsThe median time spent in the ICU was 5 days (range, 2–123 days). Patients with an underlying diagnosis of obstructive lung disease had significantly shorter ICU stays (median 4 days; range, 2–28 days) than those with restrictive lung disease (median 7 days; range, 2–123 days) (p=0.005) or pulmonary hypertension (median 10 days; range, 2–38 days) (p=0.041). Significant differences in ICU duration were observed between patients after double lung transplantation (median 10 days; range, 2–123 days) and those after single lung transplantation (median 4 days; range, 2–36 days) (p=0.004). No statistically significant difference in ICU duration was found between patients with different nutritional statuses. In those patients who could not be discharged from the ICU before the 5th day, a body mass index (BMI) below the 25th percentile was a statistically significant risk factor for ICU mortality (p<0.05).ConclusionsWe conclude that the type of transplant procedure and the underlying diagnosis are important predictive indicators of ICU duration. A poor nutritional status (BMI below the 25th percentile) is a risk factor for ICU mortality in cases of patients who stay for 5 days or longer in the ICU.

Comparing Doppler Ultrasonography and Cerebral Oximetry as Indicators for Shunting in Carotid Endarterectomy

To determine the thresholds of selective shunting in carotid endarterectomy during general anesthesia, we compared transcranial Doppler ultrasonography and cerebral oximetry (RSO2). During carotid cross-clamping, RSO2 and mean blood flow velocity in the middle cerebral artery (Vm, mca) was simultaneously monitored in 55 of 59 patients. A relative decrease in Vm, mca to <20% of preclamp velocity was the indication for selective shunting. Three patients were shunted, two because of criteria of Vm, mca and one in which Vm, mca measurements were impossible. No postoperative neurological deficits occurred. During cross-clamping, both Vm, mca (42 ± 16 vs 26 ± 12 cm/s;P < 0.001) and RSO2 (68 ± 7% vs 62 ± 8%;P < 0.01) decreased and a significant correlation between %Vm, mca and &Dgr;RSO2 was found (R2 =0.40;P = 0.003). Decreases in RSO2 >13% identified two patients later shunted; however, this threshold would have indicated unnecessary shunting in seven patients (false positives = 17%). Transcranial Doppler ultrasonography identified patients at risk for ischemia more accurately than RSO2. Relying on RSO2 alone would increase the number of unnecessary shunts because of the low specificity. Accepting higher decreases in RSO2 does not appear reasonable because it bears the risk of a low sensitivity. Implications Although cerebral oximetry was easy to apply but considerably unspecific (13% false positives), transcranial Doppler ultrasonography was more accurate in indicating the risk of cerebral hypoperfusion during carotid cross-clamping. Additionally, the improvement in cerebral blood flow velocity after inducing arterial hypertension might prevent cerebral hypoperfusion during cross-clamping.

Intrathoracic fluid volumes and pulmonary function during orthotopic liver transplantation

BACKGROUND Impaired pulmonary function is a frequent finding in patients undergoing orthotopic liver transplantation (OLT). Experimental data suggest an essential contribution of splanchnic ischemia and reperfusion as a result of intraoperative volume shifts, i.e., the accumulation of extravascular lung water (EVLW). Increases of intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) might additionally influence pulmonary capillary fluid filtration. The main objective of this study was to determine the intrathoracic volume changes during OLT and to test whether there were any relationships between intra- and extravascular volume shifts and pulmonary function, as determined by the calculation of venous admixture (QS/QT) and alveolar-arterial oxygen gradient (AaDO2). METHODS Twenty-five patients undergoing OLT were studied. Using the transpulmonary double indicator dilution method, ITBV, PBV, and EVLW were determined from the mean transit times and exponential decay times of the indocyanine green and the thermal indicator curves recorded simultaneously with a fiberoptic catheter in the descending aorta. Recordings were made after induction of anesthesia, at the end of the anhepatic stage, immediately after reperfusion, and 1 and 4 h postoperatively. RESULTS Significant increases in QS/QT related to changes of ITBV were observed after reperfusion. Only a minor impact on AaDO2 was perceived. EVLW remained constant during the study period. CONCLUSIONS Postreperfusion increases of ITBV influence pulmonary function, as demonstrated by the increase in QS/QT. However, they need not be associated with greater EVLW levels, and impact on oxygenation is less severe than assumed. Hence, sufficient mechanisms protecting oxygenation and stalling increased EVLW seem to be present during uncomplicated human OLT.

The effect of a bolus dose of intravenous lidocaine on the minimum alveolar concentration of sevoflurane: a prospective, randomized, double-blinded, placebo-controlled trial.

BACKGROUND: The anesthetic effect of volatile anesthetics can be quantified by the minimum alveolar concentration (MAC) of the drug that prevents movement in response to a noxious stimulus in 50% of patients. The underlying mechanism regarding how immobilization is achieved by volatile anesthetics is not thoroughly understood, but several drugs affect MAC. In this study, we investigated the effect of a single IV bolus dose of lidocaine on the MAC of sevoflurane in humans. METHODS: We determined the MAC for sevoflurane using the Dixon “up-and-down” method in 3 groups of patients, aged 30 to 65 years, who underwent elective surgery (30 patients per group). Study medication (placebo, 0.75 mg·kg−1 lidocaine or 1.5 mg·kg−1 lidocaine) was administered 3 minutes before skin incision after a 15-minute equilibration period and the response to skin incision was recorded (movement versus no movement). RESULTS: MAC was 1.86% ± 0.40% in the placebo and 1.87% ± 0.45% in the 0.75 mg·kg−1 lidocaine group (P = 1.00). MAC was 1.63% ± 0.24% in the 1.5 mg·kg−1 lidocaine group, which was significantly lower than that of the placebo group (mean difference of 0.23% sevoflurane [95% adjusted confidence interval {CI}, 0.03–0.43]; P = 0.022). No significant difference was observed between the 0.75 mg·kg−1 lidocaine and the placebo groups (mean difference of −0.01% sevoflurane [95% adjusted CI, −0.27 to 0.25]; P = 1). CONCLUSIONS: IV 1.5 mg·kg−1 lidocaine decreased the MAC by at least 0.03% sevoflurane (mean difference 0.23% sevoflurane [95% adjusted CI, 0.03–0.43]). We did not observe a significant reduction in the MAC of sevoflurane with the IV administration of 0.75 mg·kg−1 lidocaine.

Can Hypocapnia Reduce Cerebral Embolization During Cardiopulmonary Bypass

BACKGROUND Cerebral embolization is a major cause of central nervous dysfunction after cardiopulmonary bypass. Experimental studies demonstrate that reductions in arterial carbon dioxide tension (PaCO2) can reduce cerebral embolization during cardiopulmonary bypass. This study examined the effects of brief PaCO2 manipulations on cerebral embolization in patients undergoing cardiac valve procedures. METHODS Patients were prospectively randomized to either hypocapnia (PaCO2 = 30 to 32 mm Hg, n = 30) or normocapnia (PaCO2 = 40 to 42 mm Hg, n = 31) before aortic cross-clamp removal. With removal of the aortic cross-clamp embolic signals were recorded by transcranial Doppler ultrasonography for the next 15 minutes. RESULTS Despite significant differences in PaCO2, groups did not differ statistically in total cerebral emboli counts. The mean number of embolic events was 107 +/- 100 (median, 80) in the hypocapnic group and 135 +/- 115 (median, 96) in the normocapnic group, respectively (p = 0.315). CONCLUSIONS Due to the high between-patient variability in embolization, reductions in PaCO2 did not result in a statistically significant decrease in cerebral emboli. In contrast to experimental studies, the beneficial effect of hypocapnia on cerebral embolization could not be demonstrated in humans.

Intracranial pressure and venous cannulation for cardiopulmonary bypass

The onset of cardiopulmonary bypass (CPB) is a period of changing hemodynamics, and during this transition, the position of the aortic and venous cannulas is assessed. Increased arterial line pressures may indicate a malposition of the aortic cannula, whereas reduced venous return to the reservoir of the CPB circuit suggests suboptimal position of a venous cannula. Classically described signs of compromised venous drainage, such as engorgement of the head and neck, are rare, and incomplete obstruction of the superior vena cavae may be difficult to detect clinically but can significantly alter cerebral physiology. Impedance to superior vena caval (SVC) flow may increase intracranial pressure (ICP) and decrease cerebral perfusion pressure (CPP) (CPP 5 mean arterial pressure [MAP] 2 [ICP] (1). In the experimental setting, we have incidentally, but repeatedly, observed this effect. The same physiologic phenomenon is of relevance in the operating suite and may bear on practice. The purpose of this article is to briefly describe the influence of venous cannula position on ICP during CPB.

The use of the antioxidant tirilazad mesylate in human liver transplantation: is there a therapeutic benefit?

Objectives: To test the hypothesis whether in patients undergoing liver transplantation the antioxidant tirilazad mesylate can reduce hepatic ischaemia-reperfusion injury and improve postoperative outcome. Design: Prospective, randomised, placebo controlled trial. Setting: University hospital. Patients: 20 patients were randomised to receive either tirilazad mesylate or placebo (saline). Interventions: Patients in the tirilazad group (n = 10) received four intravenous infusions of tirilazad at 6-h intervals (men 3 mg/kg, women 3.75 mg/kg) after the induction of anaesthesia. The other patients (n = 10) served as controls. Measurements and results: Plasma levels of malonaldehyde (MDA) were determined after the induction of anaesthesia prior to the infusion of tirilazad (baseline), during the anhepatic period, and 5 min and 24 h after reperfusion. Postoperatively, alanine aminotransferase, aspartate aminotransferase, prothrombin time, and serum cholinesterase were determined daily for 1 week. Compared to baseline, plasma MDA levels did not significantly change during the anhepatic period and after reperfusion and they did not differ between groups. Postoperative liver enzymes and prothrombin time did not differ between groups, but on the first (p = 0.03) and second (p = 0.01) postoperative day cholinesterase levels were significantly higher in tirilazad-treated patients than in control patients. For neither length of stay in the intensive care unit nor hospital stay were any differences observed between groups. Conclusions: In patients undergoing liver transplantation, tirilazad does not improve overall outcome. Whether the higher cholinesterase levels on the first 2 postoperative days in tirilazad treated patients indicates an earlier recovery of liver function remains to be tested.

The impact of asymptomatic carotid artery disease on the intraoperative course of coronary artery bypass surgery.

Asymptomatic carotid artery stenosis (CAS) may result in neurological injury after coronary artery bypass surgery, but routine preoperative carotid screening is not undisputed. We studied whether routinely determined carotid duplex results, beyond detecting high-risk patients, additionally influence intraoperative course. One hundred and eight patients without new signs of impaired cerebral circulation were investigated. Anesthesiology, perfusionist records, and patient files were reviewed for patient characteristics, intraoperative variables and postoperative neurological sequelae. There was a higher incidence of prior cerebrovascular events and peripheral artery disease in CAS patients (p B /0.05). Pulsatile flow was employed more frequently in this group (p B /0.05). Severe hyperventilation, hyperglycemia, hemodilution, hyperthermia, and lactacidosis were avoided in both groups. However, labile hemodynamics of CAS patients required more corrective interventions (p B /0.05). There was also a tendency toward greater mortality. Stroke and transient ischemic attack (TIA) occurred in two patients without CAS. Since CAS was associated with a greater degree of cardiovascular instability requiring frequent measures to control hemodynamics, positive duplex results should heighten vigilance. Although CAS does not appear to be the major source of cerebral ischemia, it involves significant comorbidity.

Graft-derived macrophage migration inhibitory factor correlates with hepatocellular injury in patients undergoing liver transplantation

Experimental studies suggest that macrophage migration inhibitory factor (MIF) mediates ischemia/reperfusion injury during liver transplantation. This study assessed whether human liver grafts release MIF during preservation, and whether the release of MIF is proportional to the extent of hepatocellular injury. Additionally, the association between MIF and early allograft dysfunction (EAD) after liver transplantation was evaluated. Concentrations of MIF, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatine kinase (CK) were measured in effluents of 38 liver grafts, and in serum of recipients. Concentrations of MIF in the effluent were greater than those in the recipients’ serum before and after reperfusion (58 [interquartile range, IQR:23‐79] μg/mL vs 0.06 [IQR:0.03‐0.07] μg/mL and 1.3 [IQR:0.7‐1.8] μg/mL, respectively; both P<.001). Effluent MIF concentrations correlated with effluent concentrations of the cell injury markers ALT (R=.51, P<.01), AST (R=.51, P<.01), CK (R=.45, P=.01), and LDH (R=.56, P<.01). Patients who developed EAD had greater MIF concentrations in effluent and serum 10 minutes after reperfusion than patients without EAD (Effluent: 80 [IQR:63‐118] μg/mL vs 36 [IQR:20‐70] μg/mL, P=.02; Serum: 1.7 [IQR:1.2‐2.5] μg/mL vs 1.1 [IQR:0.6‐1.7] μg/mL, P<.001).

Katabolismus von Patienten nach Lungentransplantation

Die Lungentransplantation (LTX) ist eine immer haufiger angewen-dete Behandlungsmoglichkeit fur Patienten mit einer terminalen Lungenerkrankung. Es handelt sich dabei um eine recht inhomogene Patientenpopulation, die auf der einen Seite normal ernahrte, oft uberernahrte Lungenfibrosepatienten, auf der anderen Seite bis zur Kachexie ausgezehrte Emphysematiker umfast [6]. Bekannt ist, das sich Patienten im Anschlus an eine grosere Operation in einer katabolen Phase befinden [9]. In der folgenden Ubersicht soll diese katabole Situation einerseits im Zusammenhang mit dem praoperativen Ernahrungszustand betrachtet werden, andererseits mit der erfolgten Ernahrungstherapie.