Evaluation of Plasma Disappearance Rate Indocyanine Green Clearance as a Predictor of Liver Graft Rejection in Donor Brain Death

INTRODUCTION

There currently exist no quantitative methods to assess graft viability before the donor procurement procedure. In Europe, around 20% of liver grafts evaluated "in situ" by an experienced surgeon are discarded. The aim of this study is to evaluate the use of the plasma disappearance rate indocyanine green (PDR-ICG) clearance in predicting liver graft rejection to avoid this 20% of futile surgeries.

OBJECTIVES

To evaluate PDR-ICG as a predictor of liver graft rejection in death brain donors compared with the gold standard evaluation by an experienced surgeon.

MATERIAL AND METHODS

Prospective observational single center study. From March 2017 to July 2019, 29 donors were included in the study, 17 were men and 12 women with a median age of 68 years ± 16.9 years. Donors had an intensive care unit stay of 2 days ± 4 days. PDR-ICG was measured with PICCO2 monitor. Indocyanine green clearance dose was 0.25 mg/kg injected intravenously in the operating room just before donor procurement procedure is initiated. The surgeon was unaware of the PDR-ICG measure until the decision of graft acceptance was taken. Data regarding the donors and biopsy results were included in a prospective database.

RESULTS

PDR-ICG measure could be obtained in 10 minutes in all of the cases included. The median PDR-ICG obtained was 18%/min (range, 2.4-31%/min). Graft rejection took place in 15 out of the 29 donors. PDR-ICG value was less than 10%/min in 6 of these rejected grafts and less than 15%/min in 10 donors. All donor grafts with PDR-ICG <15% were discarded. The graft had been discarded in 5 donors with a PDR-ICG >15%.

CONCLUSIONS

In our study a plasma disappearance rate <10 would have identified the grafts that would be rejected, thus avoiding the displacement work and expense of the surgical team. These results should be confirmed in a multicentric study.

Assessment of the knowledge level of the professional as regards Patient Blood Management in their organisation. Results of the MAPBM project survey

INTRODUCTION

The Maturity Assessment Model in Patient Blood Management project involves the use of a matrix that evaluates the maturity of the centre as regards blood transfusion practice. This tool includes a questionnaire to be completed by physicians to determine their level of knowledge of patient blood management strategies in their centre.

MATERIAL AND METHODS

Forty one hospitals took part in the Maturity Assessment Model in Patient Blood Management project in 2016. The questionnaire included 10 questions, 3 about the centre, specialty, and years of experience, and 7 about patient blood management protocols in the respondent's centre. The minimum responses required per centre was calculated according to the number of beds. Responses from at least 3 different specialties were required in order to be evaluated.

RESULTS

A total of 1403 questionnaires were completed. The specialty with the highest completion rate was anaesthesiology (40.9%). The distribution as regards professional experience was homogeneous: <10 years, 33.4%, 10-20 years, 33%, and> 20 years 33.6%. Nearly three-quarters (74.2%) knew the patient blood management protocol used in their centre, and 60.7% knew the protocol for the treatment of pre-operative anaemia. Slightly fewer (72%) reported knowing the blood transfusion protocol (transfusion threshold) used in their centre, and 90% considered other factors besides haemoglobin in the decision to transfuse. Only 30.7% of professionals reported receiving periodic information on transfusion practices.

CONCLUSIONS

There is a significant lack of knowledge about preoperative anaemia and perioperative transfusion protocols used in the centres polled. Few centres provide their physicians with information on transfusion practices.

Donor Risk Index Has an Impact in Intraoperative Measure of Hepatic Artery Flow and in Clearance of Indocyanine Green: An Observational Cohort Study

BACKGROUND

The increase in indications for liver transplantation has led to acceptance of donors with expanded criteria. The donor risk index (DRI) was validated with the aim of being a predictive model of graft survival based on donor characteristics. Intraoperative arterial hepatic flow and indocyanine green clearance (plasma clearance rate of indocyanine green [ICG-PDR]) are easily measurable variables in the intraoperative period that may be influenced by graft quality. Our aim was to analyze the influence of DRI on intraoperative liver hemodynamic alterations and on intraoperative dynamic liver function testing (ICG-PDR).

METHODS

This investigation was an observational study of a single-center cohort (n = 228) with prospective data collection and retrospective data analysis. Measurement of intraoperative flow was made with a VeriQ flowmeter based on measurement of transit time (MFTT). The ICG-PDR was obtained from all patients with a LiMON monitor (Pulsion Medical Systems AG, Munich, Germany). DRI was calculated using a previously validated formula. Normally distributed variables were compared using Student's t test. Otherwise, the Mann-Whitney U test or Kruskal-Wallis test was applied, depending on whether there were 2 or more comparable groups. The qualitative variables and risk measurements were analyzed using the chi-square test. P < .05 was considered statistically significant.

RESULTS

DRI score (mean ± SD) was 1.58 ± 0.31. The group with DRI >1.7 (poor quality) had an intraoperative arterial flow of 234.2 ± 121.35 mL/min compared with the group having DRI < 1.7 (high quality), with an intraoperative arterial flow of 287.24 ± 156.84 mL/min (P = .02). The group with DRI >1.70 had an ICG-PDR of 14.75 ± 6.52%/min at 60 minutes after reperfusion compared to the group with DRI <1.70, with an ICG-PDR of 16.68 ± 6.47%/min at 60 minutes after reperfusion (P = .09).

CONCLUSION

Poor quality grafts have greater susceptibility to ischemia-reperfusion damage. Decreased intraoperative hepatic arterial flow may represent an increase in intrahepatic resistance early in the intraoperative period.

Cardiac output monitoring with pulmonary versus transpulmonary thermodilution during liver transplantation: interchangeable methods?

BACKGROUND

Liver transplantation (LT) implies hemodynamic instability, making invasive monitoring of cardiac output (CO) mandatory. Intermittent thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO. The agreement between PAC and new monitoring methods in LT needs to be further investigated. Our aim is to clarify whether cardiac index (CI) measurements with transpulmonary intermittent thermodilution, and continuous pulmonary thermodilution methods agree sufficiently with those performed intermittently with PAC to be considered interchangeable during LT.

METHODS

We studied prospectively hemodynamic parameters of 72 consecutive patients undergoing LT. Each CI was obtained simultaneously with three different techniques: intermittent (PACi) and continuous (CCI) pulmonary artery thermodilution with PAC, and intermittent transpulmonary thermodilution (TPTD) with PiCCO2 in 8 time points of the procedure, obtaining 1350 paired measurements. Exclusion criteria was retransplantation. The statistical Bland Altman method for repeated measures was used to assess agreement, and polar plot methodology to evaluate trending ability.

RESULTS

Analysis of agreement between PACi and TPTD measurements (N.=474 paired measurements) showed a bias of -0.42 L/min/m2, 95% limits of agreement (95%LoA) of ±1.5 L/min/m2 and percentage error of 45%. PACi-CCI comparisons (N.=431) showed bias of -0.02 L/min/m2, 95%LoA of ±1.96 L/min/m2, and percentage error of 64%. These results demonstrated questionable clinical agreement between PACi and TPTD, and no agreement between PACi and CCI. TPTD and CCI showed poor CO trending ability.

CONCLUSION

Continuous pulmonary thermodilution with PAC is not an alternative monitoring method of CO. Transpulmonary thermodilution CO monitoring with PiCCO2 shows too questionable agreement with the clinical gold standard (PACi) being in the limit of acceptance to be considered interchangeable during liver transplantation.

"Small-for-flow" syndrome: shifting the "size" paradigm

The "small-for-size" syndrome and "post-hepatectomy liver failure" refers to the development of liver failure (hyperbilirubinemia, coagulopathy, encephalopathy and refractory ascites) resulting from the reduction of liver mass beyond a certain threshold. This complication is associated with a high mortality and is a major concern in liver transplantation involving reduced liver grafts from deceased and living donors as well as in hepatic surgeries involving extended resections of liver mass. The limiting threshold for liver resection or transplantation is currently predicted based on the mass of the remnant liver (or donor graft) in relation to the body weight of the patient, with a ratio above 0.8 being considered safe. This approach, however, has proved inaccurate, because some patients develop the "small-for-size" syndrome despite complying with the "safe" threshold while other patients who surpass the threshold do not develop it. We hypothesize that the development of the "small-for-size" syndrome is not exclusively determined by the ratio of the mass of the liver remnant (or graft) to the body weight, but it is instead strictly determined by the hemodynamic parameters of the hepatic circulation. This hypothesis is based in recent clinical and experimental reports showing that relative portal hyperperfusion is a critical factor in the development of the "small-for-size" syndrome and that maneuvers that manipulate the hepatic vascular inflow are able to prevent the development of the syndrome despite liver-to-body weight ratios well below the "limiting" threshold. Measurements of hepatic blood flow and pressure, however, are not routinely performed in hepatic surgeries. Focusing on the "flow" rather than in the "size" may improve our understanding of the pathophysiology of the "small-for-size" syndrome and "post-hepatectomy liver failure" and it would have important implications for the clinical management of patients at risk. First, hepatic hemodynamic parameters would have to be measured in hepatic surgeries. Second, these parameters (in addition to liver mass) would be the principal basis for deciding the "safe" threshold of viable liver parenchyma. Third, the hepatic hemodynamic parameters are amenable to manipulation and, consequently, the "safe" threshold may also be manipulated. Shifting the paradigm from "small-for-size" to "small-for-flow" syndrome would thus represent a major step for optimizing the use of donor livers, for expanding the indications of hepatic surgery, and for increasing the safety of these procedures.

Radial to femoral arterial blood pressure differences during liver transplantation

This observational study compared femoral and radial arterial blood pressure in 72 patients undergoing liver transplant surgery. Simultaneous femoral and radial arterial blood pressures, cardiac index, core temperature and vasoconstrictor therapy were recorded at seven time points during the operation. No significant differences between radial and femoral pressures were found at the start of surgery. Femoral and radial systolic arterial blood pressures were statistically significantly different during liver reperfusion (mean (SD) arterial pressure = 92 (22) mmHg vs. 76 (22) mmHg, p < 0.01). Mean arterial blood pressures showed no statistically significant differences throughout the study. Vasoconstrictor drug administration was associated with a larger systolic pressure difference between femoral and radial arteries (28 (24) mmHg in patients being given vasoconstrictor drugs vs. 9 (19) mmHg in patients not needing vasoconstrictors during reperfusion, p < 0.001). In conclusion, differences in systolic arterial blood pressure occur between femoral and radial arterial monitoring sites during liver reperfusion, and in particular in patients being given vasoconstrictor therapy. Thus, if femoral arterial monitoring is not available, clinicians should rely on mean rather than systolic arterial pressure measurements from a radial artery catheter during liver transplantation.

[Paravertebral analgesia in thoracic surgery]

Managing postoperative pain from thoracotomy is one of the greatest challenges anesthesiologists face in daily practice. Proper management is assumed to improve the patient's prognosis. The thoracic paravertebral block, following its rediscovery, is being used with increasing frequency and success for both surgery and recovery from thoracotomy, challenging the supremacy of thoracic epidural analgesia, which to date has been considered the gold standard. We describe the history, anatomy, techniques and complications of the thoracic paravertebral block and review published randomized controlled trials comparing the thoracic paravertebral block to placebo and to epidural analgesia. In view of published evidence, it seems that the thoracic paravertebral block may replace the thoracic epidural technique as the gold standard for providing analgesia for patients undergoing thoracotomy.

[Recombinant activated factor VII used in a man with refractory bleeding from a stab wound injuring the liver and kidney]

A 30-year-old man bled massively from a stab wound that injured his liver and right kidney and entered a life-threatening cycle of transfusion, hypothermia, coagulopathy, and rebleeding in spite of surgery and aggressive resuscitation. He was given a single dose of recombinant activated factor VII (rVIIa; NovoSeven, Novo Nordisk, Denmark) in a final attempt to save his life. The patient responded favorably, as bleeding stopped almost immediately and coagulation markers became normal. Clinical course following rVIIa administration was good. Severe bleeding in the trauma patient needing massive transfusion can become complicated by dilutional coagulopathy and hypothermia. Therapy with rVIIa is a promising aid to controlling bleeding in the repeatedly transfused patient who does not respond to standard replacement of blood products.

Autonomic neuropathy in end-stage cirrhotic patients and evolution after liver transplantation

Autonomic neuropathy (AN), which is frequently observed in cirrhosis patients, has been associated with a higher mortality. We have prospectively evaluated the prevalence of AN, its relationship with the degree of liver dysfunction and circulatory disturbances, and the evolution of AN after liver transplantation (LT) in 62 end-stage liver cirrhosis patients. AN was evaluated by seven cardiovascular tests assessing sympathetic or parasympathetic function before and 6 months after LT. Patients were classified as showing absent (A), early (E), or definite dysfunction (D). AN appeared in 67.7% of cases (E: 24.2%, D: 43.5%) without relation to liver disease etiology. Parasympathetic dysfunction was more prevalent than sympathetic dysfunction (59.7% vs. 20.9%). AN was significantly related to Child-Pugh score. Hyperdynamic circulation was more marked in the D than the A group as shown by a greater cardiac output (CO)(9 vs. 7.3 L/min) and a lower peripheral resistance (SVR)(666 vs. 866 dyn.s.cm(-5)). Moreover, AN scores significantly correlated with CO and SVR. Overall the prevalence of AN decreased 6 months after LT (67.7% vs 48%) due to a significant reduction in definite AN (43.5 vs. 14.8%; P<.05). AN improved in 70% of cases after LT. Sympathetic dysfunction remained in only one patient. We conclude that AN is frequent in liver transplant candidates; its severity is associated with the degree of liver failure. Systemic circulatory disturbances seem to correlate with the severity of AN. AN is clearly improved by LT. The evaluation of AN may contribute to a better selection of LT recipients.

Autonomic neuropathy is associated with hemodynamic instability during human liver transplantation

INTRODUCTION

End-stage liver disease is frequently associated with autonomic neuropathy (AN). The hemodynamic changes during liver transplantation (LT) require an adequate autonomic response to maintain cardiovascular stability.

PATIENTS AND METHODS

Forty-one patients undergoing LT were evaluated for the influence of AN on the evolution after LT. AN was previously evaluated by seven cardiovascular tests assessing sympathetic (Sy) or parasympathetic (P) function. Patients were classified as absent (A), early (E), or definite dysfunction (D). A hemodynamic study was performed before and after vascular clampings. The analysis included the duration of LT, transfusion requirements, intra-operative artenal hypotensive episodes, incidence of postreperfusion syndrome (PRS), cardiac arrhythmias and vasoactive drug requirements.

RESULTS

The hyperdynamic circulation worsened during surgery in D patients, as shown by a significantly increased cardiac output and a significantly decreased systemic vascular resistance. The incidence of PRS was greater in the AN group. Arterial hypotension during the neohepatic period was more frequent among patients with AN, more frequently requiring vasoconstrictor and inotropic therapy.

CONCLUSIONS

AN is associated with hemodynamic impairment and with increased vasoactive drug requirements during liver transplantation, probably associated with impaired reflex vasoconstrictor responses to surgical manipulations and changes of blood volume. AN may be associated with a greater surgical risk during LT. Preoperative evaluation of AN may select a high-risk population of LT recipients.

Fatal paradoxical air embolism during liver transplantation

We describe a case of fatal paradoxical coronary air embolism during liver transplantation. The literature on the diagnosis and prophylaxis of paradoxical air embolism during liver transplantation is reviewed and discussed.

Presence of a nitric oxide synthase inhibitor in the graft efflux during reperfusion in human liver transplantation

Involvement of the nitric oxide (NO) system in complications following human orthotopic liver transplants (OLT) has been reported, but the contribution of the graft to the modulation of the NO system during reperfusion in normal OLT has not been characterized. We have studied the contribution of the graft efflux to the modulation of the NO system in 20 consecutive OLT. We evaluated its effects on isolated vascular reactivity of the rabbit and on rat cultured macrophages stimulated with lipopolysaccharide (LPS). In none of the donor liver biopsies was expression of inducible NO synthase (iNOS) activity by Northern or Western blot analysis found. Graft efflux after the onset of liver reperfusion, but not pre-transplant patient plasma, reversibly inhibited the acetylcholine-induced relaxation of norepinephrine-contracted rabbit aortic rings. Moreover, graft efflux reversibly inhibited NO production in rat macrophages treated with LPS, as evidenced by both a decrease in nitrite plus nitrate formation and a decrease in the production of [14C]citrulline from [14C]arginine. Addition of a 10% dilution of graft efflux to cultured rat macrophages incubated with LPS increased iNOS mRNA levels, suggesting direct inhibition of the enzyme but not of its expression. These results cannot be ascribed to the depletion of arginine the iNOS substrate since they can be reproduced even in the presence of an excess (10 mM) of exogenously added arginine. No correlation was found between the iNOS inhibitory activity in each sample and the corresponding clinical parameters related to either the graft function after the OLT or the existence of post-reperfusion syndrome. Our results indicate the existence of a soluble factor in the graft efflux from human OLT that reversibly and unspecifically inhibits NOS activity. Its involvement in the physiology and/or pathology of human liver diseases deserves further study.

Arterial oxygenation during one-lung ventilation: combined versus general anesthesia

The optimal anesthetic management of patients undergoing thoracotomy for pulmonary resection has not been definitely determined. We evaluated whether general i.v. anesthesia (propofol-fentanyl) provides superior PaO2 during one-lung ventilation (OLV) compared with thoracic epidural anesthesia (TEA) with supplemental local and general anesthetics. We studied 60 patients who had prolonged periods of OLV for elective thoracic surgery for lung cancer and who were prospectively randomized into two groups. In 30 patients (GA group), fentanyl/propofol/rocuronium anesthesia was used. Another 30 patients (TEA group) were anesthetized with propofol/rocuronium/epidural thoracic bupivacaine 0.5%. A double-lumen endotracheal tube was inserted, and mechanical ventilation with 100% oxygen was used during the entire study. Arterial and venous blood gases were recorded before surgery in a lateral position with two-lung ventilation, 15 and 30 min after OLV (OLV + 15 and OLV + 30, respectively) in all patients. We measured PaO2, venous central oxygen tension, arterial and central venous oxygen saturation, venous admixture percentage (Qs/Qt%), and arterial and central venous oxygen content. The mean values for PaO2 during OLV in the GA group after 15 min (175 mm Hg) and 30 min (182 mm Hg) were significantly (P < 0.05) higher compared with the TEA group (120 and 118 mm Hg, respectively). Furthermore, Qs/Qt% was significantly (P < 0.05) increased in the TEA group during OLV. There were no other significant differences. We conclude that using the TEA regimen is associated with a lower PaO2 and a larger intrapulmonary shunt during OLV than with total i.v. anesthesia alone.

IMPLICATIONS

Sixty patients undergoing elective lung surgery during a prolonged period of intraoperative one-lung ventilation were studied and randomized to receive general i.v. anesthesia or general i.v. anesthesia combined with thoracic epidural anesthesia. The arterial oxygenation in the first group was better than that in the second group during one-lung ventilation.

Response to clamping of the inferior vena cava as a factor for predicting postreperfusion syndrome during liver transplantation

Postreperfusion syndrome (PRS) is an important cause of hemodynamic deterioration during orthotopic liver transplantation (OLT). We retrospectively studied 94 patients who had undergone OLT in an effort to establish whether the hemodynamic response to clamping of the inferior vena cava (IVC) could be used to predict hemodynamic behavior on reperfusion of the grafted liver. PRS was defined as a decrease in the mean arterial pressure of more than 30% below the baseline value for more than 1 min during the first 5 min after reperfusion of the graft. The patients were divided into two groups: those who developed PRS (PRS group) and those who did not (non-PRS group). We analyzed hemodynamic response before (dissection stage) and after (anhepatic stage) clamping of the IVC. Based on multivariate analysis methods (logistic regression), the percentage of change in the vascular resistance index from before clamping to after clamping of the IVC was an indicator of the risk of developing PRS, with an adjusted odds ratio of 1.04 for each unit of change (ENTER method, P = 0.01). In the non-PRS group, clamping of the IVC was followed by a 47.1% decrease in the cardiac index, compared with a 27.9% decrease in the PRS group (P < 0.05). The systemic vascular resistance index (SVRI) increased by 49% in the PRS group, as opposed to 85.7% in the non-PRS group (P < 0.05). PRS occurred in only 17.5% of patients in whom the SVRI increased by more than 50%. We conclude that the integrity of the vasoconstrictive response (increase in the peripheral vascular resistance greater than 50%) as measured immediately after clamping of the IVC correlates with occurrence of PRS.

[The liver transplant program of the Hospital General Universitario Gregorio Marañón: an analysis of the first 100 patients]

During a 3-year period between 1990 and 1993, 100 patients received orthotopic liver transplantation at the "Gregorio Marañón" University General Hospital. The mean age of the patients was relatively high (46.9 +/- 10 years), with an important number of cirrhotic patients (91%). The rate of primary liver failure was relatively low (4.5% of transplantations) although 12 cases with more than 55 years were included in the present series. Eleven retransplantations were performed, 8 for early failure of the graft and 3 for chronic failure. Postoperative complications of the graft were vascular in 9 cases, biliary in 17 cases, and acute rejection (cellular) in 70 patients, although only 50 of these patients required treatment with steroid boluses. Infections were diagnosed in 60 cases with 80% of major infections, 6 of them caused by Aspergillus fumigatus that were lethal in all the cases. Postoperative survival was 82%, 72%, 69% and 69% at 1 month, 6 months, 1 year and 2 years respectively.

[Internal jugular vein catheterization performed by resident and staff physicians]

OBJECTIVES

To analyse complications in the catheterization of the internal jugular vein using the Boulanger technique and to establish a rating of difficulty and risk when the procedure is carried out by physicians in training.

MATERIAL AND METHODS

This was a prospective study of 296 internal jugular vein (IJV) catheterizations by the Boulanger technique carried out by physicians in training (group R2 and group R3-4) or by departmental staff physicians (group staff). Time taken for venous catheterization, rate of success and complications were recorded for each physician performing the procedure.

RESULTS

The complication most often observed (11.4%) was puncture of the carotid artery (14.3% group R2, 10% group R3-4 and 8.2% staff), followed by arrhythmia upon insertion of the metal guide (1.6%). There were no instances of pneumothorax or hemothorax, nor any other of the early complications considered infrequent. Success ranged from 68.8% for group R2 to 85.7% for staff. Mean time used in group R2 was 238.7 seconds, while for staff it was 118.3 seconds.

CONCLUSION

We suggest that the Boulanger technique for catheterization of the internal jugular vein is a good one and is not particularly hazardous when performed by resident physicians in training.

[Intracavitary electrocardiography. A useful method for checking the correct localization of central venous catheters]

A placement technique for central venous catheters (CVC) using the intracavitary electrocardiography (ICECG) as well as three different connection systems of the CVC to the electrocardiographic monitor are described. The aim of the present study was to evaluate the correct placement of the CVC by this technique with posterior radiologic confirmation being carried out. The study was undertaken in 30 patients connecting a CVC to a negative electrode of the standard lead II and the positive to the left leg. The CVC was advanced and the changes in the morphology of the "P" wave as it passed along the superior vena cava (SVC) to the right auricle (RA) were observed. In 28 of the 30 patients (93.3%) a biphasic "P" wave (right auricle) was achieved with the CVC being thereafter withdrawn until the SVC (this location was radiologically confirmed posteriorly). In 2 patients (6.6%) a biphasic "P" wave was not obtained and an abnormal position of the CVC was radiologically demonstrated at surgery (one in the ipsilateral subclavian vein and the other had a ring within the right subclavian vein impeding progression). The mean time used in the performance of this technique was 220 +/- 40 s. It is concluded that intracavitary electrocardiography is a simple, easy to learn and perform technique which does not delay surgical procedure and it is a reliable method for placing the end of the CVC.