Effect of cold perfusion and perfluorocarbons on liver graft ischemia in a donation after cardiac death model.

BACKGROUND: Effects of two perfluorocarbon (PFC) formulations (perfluorodecalin emulsion and perfluorodecalin liquid) on the quality of liver graft preservation, in a donation after cardiac death (DCD) rat model, were investigated. The significance of continuous graft perfusion during cold preservation was also explored. MATERIALS AND METHODS: DCD model: 30 min after cardiopulmonary arrest was initiated, livers were excised and flushed with cold University of Wisconsin (UW) solution (± PFC) and preserved in the same solution for 8 h. The study groups were preserved as follows: group 1: no perfusion; group 2: perfusion with UW; group 3: PFC was administered before cardiac arrest and the liver was perfused with UW alone; and groups 4 and 5: perfused with UW + 1 of two PFCs. In a baseline group used only for comparison of gene expression, livers were quick-frozen after cardiac arrest. Microarrays were used to analyze liver messenger RNA transcripts. Histopathologic, immunohistochemical, and ADP/ATP ratio evaluations were performed to assess the quality of graft preservation. RESULTS: Significant decreases in downregulation and increases in upregulation of hepatic genes (relative to baseline) were demonstrated in all perfusion groups. This trend was most pronounced in the PFC groups. Lower fat content and ADP/ATP ratio and a reduction in Caspase 3 activation were found in all perfusion groups. CONCLUSION: Hypothermic perfusion of rat DCD liver grafts with oxygenated UW solution (± PFC) produced superior preservation compared with nonperfusion storage. The observed changes in expression of hepatic genes may represent a protective effect in the DCD model.

Early exposure to anesthesiology: a summer preceptorship program for first-year medical students.

Introduction: A 4-week summer preceptorship offered first-year medical students early exposure to anesthesiology following their preclerkship courses in pharmacology and cardiopulmonary physiology. The main objective was to provide students with clinical skills and prepare them for rotations while immersing them in a unique experience, introducing a specialty not covered in core rotations. Methods: Participants were selected via their responses to an application. In addition to shadowing anesthesiologists, curriculum components included weekly faculty lectures on core aspects of anesthesiology (introductory basics, perioperative drugs, airway, and crisis management); multiple simulation labs (workstation setup, intubation clinics, intravenous and central line placement, ultrasound techniques); research opportunities; and mentorship from physicians and senior medical students. The program culminated in each student successfully leading a simulated case to receive a certificate of completion. Results: A survey of 15 participants revealed significant improvements in ability to intubate (P < 0.05), ability to perform a transthoracic echocardiogram (P < 0.05), interest in anesthesiology as a specialty (P < 0.05), and preparedness for future rotations (P < 0.05). Discussion: This program accelerates clinical exposure for preclerkship students, providing insights into anesthesiology early in their medical journey. It provides research and mentorship, fosters professional growth, and enhances individual competitiveness for residency program applications.

Perioperative Management of a Donation After Circulatory Death Heart Transplant in a Recipient With a Persistent Left Superior Vena Cava.

A 60-year-old male with end-stage heart failure due to non-ischemic cardiomyopathy and mitral regurgitation presented for a donation after circulatory death (DCD) orthotopic heart transplantation. Intraoperatively, a persistent left superior vena cava (PLSVC), absent innominate vein, and small right superior vena cava were discovered. A bicaval technique was performed, using an interconnecting prosthetic conduit to anastomose the PLSVC with the right atrial appendage and an interposition graft to the native R SVC. After surgery, a transthoracic echocardiogram showed a left ventricular ejection fraction of 60-65% and improved systolic function. The postoperative course was uneventful, with discharge home after 16 days.

Efficacy of nasal continuous positive airway pressure as a preferred airway management during intravenous sedation of patients undergoing transcatheter aortic valve replacement.

Background: As the incidence of aortic stenosis is increasing in correlation with the aging population, symptomatic patients commonly require valve replacement procedures. If left untreated, symptomatic aortic stenosis can lead to death in 2 to 3 years. Often, transcatheter aortic valve replacement (TAVR) procedures are performed with the assistance of oxygenation via nasal cannula. However, oxygenation achieved through a nasal continuous positive airway pressure (nCPAP) device could be a more optimized strategy for patients without any sacrifice in efficacy compared to nasal cannula. Methods: A retrospective chart review was conducted on 28 patients at Baylor University Medical Center who presented to the operating room for a TAVR between January and October 2021. Fourteen patients received oxygenation via nasal cannula (control group) and 14 received oxygenation with nCPAP. Information gathered included method of oxygenation, length of stay, episodes of hypoxia (defined as sustained oxygen saturation <92% for at least 1 minute), paravalvular leak, pacemaker placement, and mean atrial valve (AV) gradient before and after the procedure. Results: In the nCPAP group, the average length of stay was 2.79 days vs 2.71 days in the nasal cannula group. In the nCPAP group, no patient required a permanent pacemaker, while the nasal cannula group had a 40% rate of permanent pacemaker placement. The average preprocedure AV gradient was 51.14 in the nCPAP group and 42.57 in the nasal cannula group. The average postprocedure AV gradient was 8.5 in the nCPAP group and 5.36 in the nasal cannula group. Both groups had an intensive care unit admission rate of 0%. The rate of paravalvular leak was 35.7% in the nCPAP group and 28.6% in the nasal cannula group. The nCPAP group had an average of 0 episodes of hypoxia and the nasal cannula group had an average of 0.93 episodes of hypoxia. Conclusion: The findings demonstrate the viability of nCPAP as an effective method of oxygenation during intravenous sedation of TAVR patients when compared to oxygenation achieved via nasal cannula during TAVRs.

An Approach to Anesthetic Management of Venous Anomalies and Outflow Reconstruction in Liver Transplants.

Hepatic venous outflow is a pivotal factor in liver transplant. However, venous anomalies and the potential for hepatic venous congestion continue to remain major points of concern to ensure the viability of transplanted livers and maximize regenerative capacity. We present a 66-year-old patient undergoing liver transplantation who was found to have anomalous venous drainage requiring venous anastomoses. To ensure adequate venous flow and minimize the possibility of graft congestion and liver dysfunction, the anesthetic management of the patient's hemodynamic status was of utmost importance. The use of osmotic diuretics and intraoperative sonography was used to ensure adequate perfusion.

Use of a third-generation perfluorocarbon for preservation of rat DCD liver grafts.

BACKGROUND: Cold storage in any of the commonly used preservation solutions is not always adequate for donation after cardiac death (DCD) liver grafts due to prolonged warm ischemic time. In this study, we used a third-generation perfluorocarbon (PFC), Oxycyte, for DCD liver graft preservation in a rat model. MATERIALS AND METHODS: Twenty-eight rats (14 in each group) were used. Thirty minutes after cardiopulmonary arrest, livers were harvested and flushed with a cold and pre-oxygenated solution of either University of Wisconsin (UW) or UW + 20% PFC. After 8 h of cold preservation in either of the investigated solutions, liver graft specimens were analyzed for evidence of ischemic injury. Hemotoxylin and eosin staining (H and E), as well as immunohistochemical analysis with anti-cleaved caspase 3 antibody, was performed. Levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the preservation solution were analyzed at 1 and 8 h during preservation. RESULTS: In the PFC group, the degree of cell congestion, vacuolization and necrosis were all significantly less than in the UW group (P = 0.002-0.004). The number of cells with a positive cleaved caspase 3 antibody reaction was reduced by about 50% in comparison with the UW group (P < 0.006). The AST level in the PFC group was significantly less than in the UW group after 8 h of preservation (P < 0.048). CONCLUSION: The addition of PFC to UW solution significantly decreases the degree of histologic damage in rat DCD liver grafts. This preservation strategy can be potentially helpful for organ preservation after prolonged warm ischemia.

Combined Tricuspid Valve Repair and Orthotopic Liver Transplantation in a Patient With Severe Tricuspid Regurgitation and Pulmonary Hypertension.

Severe pulmonary hypertension and severe tricuspid regurgitation are often considered strict contraindications for orthotopic liver transplantation. A combined approach of tricuspid repair and subsequent liver transplantation could provide a novel approach for patients with severe pulmonary hypertension and tricuspid regurgitation to undergo orthotopic liver transplantation. A 62-year-old male with a history of end-stage renal disease on hemodialysis, cirrhosis, and third-degree atrioventricular heart block status post single lead pacemaker insertion presented for an orthotopic liver transplant. However, after placement of a Swan-Ganz catheter by the anesthesia team, the patient's central venous pressure was found to be high, and his mean pulmonary artery pressure was 40 mmHg. His case was canceled due to concern for poor postoperative outcomes after a subsequent transesophageal echocardiogram revealed a severely dilated right heart and 4+ tricuspid regurgitation with flow reversal into the hepatic veins. After discussion among the hospital's transplant committee, the patient was planned to have a tricuspid valve repair, liver transplant, and kidney transplant surgery several months later. The patient successfully underwent tricuspid valve repair and orthotopic liver transplant and then kidney transplant the following day.

Tranexamic Acid Use Intra-Operatively Decreases the Need for Blood Transfusions and Post-Operative Edema in Temporomandibular Joint Surgeries.

Temporomandibular joint (TMJ) surgeries cover a vast assortment of surgical procedures such as tooth extractions, tissue biopsies, and extensive maxillofacial surgeries. Major complications that occur during and after TMJ surgeries include uncontrolled bleeding, considerable blood loss, serious infections, and edema. Tranexamic acid (TXA) is an antifibrinolytic agent that reduces blood loss by inhibiting the enzymatic breakdown of fibrin. Currently, TXA is widely used in various orthopedic surgeries to reduce bleeding and decrease the need for blood transfusions. In this study, we observed five patients undergoing major TMJ replacement surgeries and administered TXA during the procedure. The principal aim of this study was to examine the association between TXA administration during TMJ replacement surgery and blood loss and tissue edema.

Nasal Continuous Positive Airway Pressure as a Preferred Airway Management During IV Sedation of Obese Patients With Obstructive Sleep Apnea Undergoing Functional Luminal Imaging Probe Panometry.

The functional luminal imaging probe (FLIP) utilizes high-resolution planimetry to provide information regarding esophagogastric junction (EGJ) diameter, EGJ distensibility, and reactive contractile patterns of the esophageal body. This is an FDA-approved measurement tool utilized to both diagnose and measure various upper gastrointestinal disorders. While patients are sedated during FLIP panometry, significant respiratory variations can affect the quality of FLIP panometry results. Nasal continuous positive airway pressure (CPAP) can be utilized to prevent intraoperative or postoperative hypoxia in obese patients as well as those with obstructive sleep apnea (OSA). In this retrospective chart review, we compared obese patients with a diagnosis of OSA who underwent FLIP panometry utilizing nasal CPAP as airway management against a group who underwent the same procedure with a nasal cannula to evaluate the incidence of hypoxia, hypercapnia, variation in cardiovascular dynamics, and the quality of FLIP panometry readings.

Iatrogenic Arteriovenous Fistula Secondary to Percutaneous Coronary Intervention Causing Severe Decompensated Heart Failure.

Congestive heart failure has long been a well-known cause of both morbidity and mortality for thousands of people worldwide. Consequences of decompensated heart failure are systemic and widespread, including but not limited to pulmonary edema, dyspnea, hypoxia, peripheral edema, and end-organ hypoperfusion. Common etiologies of congestive heart failure include systemic hypertension, coronary artery disease, longstanding alcohol abuse, valvular dysfunctions, and myocarditis. While the vast majority of congestive heart failure cases are secondary to one of these common etiologies, there is a subset of cases that cannot be traced to any of these causes and are most often grouped under the category of idiopathic. One rarely seen etiology of decompensated heart failure is an arteriovenous fistula, whether naturally occurring or iatrogenic. We report a case of an iatrogenic AV fistula secondary to percutaneous coronary intervention causing severe decompensated heart failure that was successfully treated with surgical ligation.

Inadvertent Traumatic Fracture of Central Venous Catheter during Procurement, Transmitted Through Solid Organ Transplant.

Central venous catheters play a pivotal role in the perioperative support of critically ill patients. They are used for administration of fluids, vasopressors, blood products, and various medications; however, their use may be associated with serious complications, such as catheter fracture and embolization. While most data on catheter fracture embolization consist of isolated case reports, only a few studies have examined patients with central venous catheter embolism. We report a traumatic inadvertent transection of central venous catheter that migrated through a donor transplanted liver and was found to be lodged in the recipient's right ventricle. The catheter was retrieved under fluoroscopy using a trilobed snare device.

Use of methylene blue for treatment of severe sepsis in an immunosuppressed patient after liver transplantation.

Sepsis in the immunosuppressed patient is associated with very high mortality and morbidity. Treatment of sepsis in immunocompromised patients is especially challenging due to an unbalanced systemic inflammatory reaction with subsequent development of profound vasoplegia. Methylene blue (MB) has been successfully used for the treatment of refractory hypotension, but its use has not previously been reported for treatment of sepsis in immunosuppressed patients. The mechanism of MB's action is thought to be due to its inhibitory effect on cGMP-mediated vasodilatation. This case report describes the successful use of MB for treatment of severe septic shock in an immunosuppressed patient after liver transplantation. Hypotension in this patient was refractory to volume repletion and a combination of vasopressors. After MB administration, hemodynamic stability was rapidly reestablished. In the setting of severe sepsis in an immunosuppressed patient, MB should be considered early as a therapeutic option for treatment of refractory vasoplegia.

Functional role of bone morphogenetic protein-4 in isolated canine parietal cells.

Bone morphogenetic protein (BMP)-4 is an important regulator of cellular growth and differentiation. Expression of BMP-4 has been documented in the gastric mucosa. We reported that incubation of canine parietal cells with EGF for 72 h induced both parietal cell morphological transformation and inhibition of H(+)/K(+)-ATPase gene expression through MAPK-dependent mechanisms. We explored the role of BMP-4 in parietal cell maturation and differentiation. Moreover, we investigated if BMP-4 modulates the actions of EGF in parietal cells. H(+)/K(+)-ATPase gene expression was examined by Northern blots and quantitative RT-PCR. Acid production was assessed by measuring the uptake of [(14)C]aminopyrine. Parietal cell apoptosis was quantitated by Western blots with anti-cleaved caspase 3 antibodies and by counting the numbers of fragmented, propidium iodide-stained nuclei. MAPK activation and Smad1 phosphorylation were measured by Western blots with anti-phospho-MAPK and anti-phospho-Smad1 antibodies. Parietal cell morphology was examined by immunohistochemical staining of cells with anti-H(+)/K(+)-ATPase alpha-subunit antibodies. BMP-4 stimulated Smad1 phosphorylation and induced H(+)/K(+)-ATPase gene expression. BMP-4 attenuated EGF-mediated inhibition of H(+)/K(+)-ATPase gene expression and blocked EGF induction of both parietal cell morphological transformation and MAPK activation. Incubation of cells with BMP-4 enhanced histamine-stimulated [(14)C]aminopyrine uptake. BMP-4 had no effect on parietal cell apoptosis, whereas TGF-beta stimulated caspase-3 activation and nuclear fragmentation. In conclusion, BMP-4 promotes the induction and maintenance of a differentiated parietal cell phenotype. These findings may provide new clues for a better understanding of the mechanisms that regulate gastric epithelial cell growth and differentiation.

Regulation and function of the sonic hedgehog signal transduction pathway in isolated gastric parietal cells.

Shh (Sonic hedgehog) regulates gastric epithelial cell differentiation. We reported that incubation of purified canine parietal cells with epidermal growth factor (EGF) for 6-16 h, stimulates H(+)/K(+)-ATPase alpha-subunit gene expression through the activation of Akt. We explored if Shh mediates some of the actions of EGF in the parietal cells. EGF induced a 6-fold increase in Shh expression, measured by Western blots, after 5 h of incubation. This effect was inhibited by both the phosphatidylinositol 3-kinase inhibitor LY294002 and by transduction of the cells with an adenoviral vector expressing dominant negative Akt. EGF stimulated the release of Shh-like immunoreactivity from the parietal cells, after 16 h of incubation. Shh induced H(+)/K(+)-ATPase alpha-subunit gene expression, assessed by Northern blots, it stimulated a luciferase reporter plasmid containing the EGF-responsive sequence (ERE) of the canine H(+)/K(+)-ATPase alpha-subunit gene promoter, and it induced parietal cell nuclear protein binding to the ERE. Gli transcription factors mediate the intracellular actions of Shh. Co-transfection of the parietal cells with the H(+)/K(+)-luc plasmid together with one expressing Gli2, induced H(+)/K(+)-luciferase activity 5-fold, whereas co-transfection of the cells with the H(+)/K(+)-luc plasmid together with one expressing dominant negative Gli2, inhibited EGF induction of H(+)/K(+)-luciferase activity. Identical results were observed in the presence of the Shh signal transduction pathway inhibitor, cyclopamine. Transfection of the cells with dominant negative Akt inhibited EGF, but not Shh stimulation of H(+)/K(+)-ATPase-luciferase activity. Thus, EGF but not Shh signals through Akt. Preincubation of the cells for 16 h with either Shh or EGF enhanced histamine-stimulated [(14)C]aminopyrine uptake by 50%. In conclusions, some of the actions of EGF in the parietal cells are mediated by the sequential activation of the Akt and the Shh signal transduction pathways. These effects might represent novel mechanisms mediating the actions of growth factors on gastric epithelial cell differentiation.

Intracellular mechanisms mediating the anti-apoptotic action of gastrin.

We previously reported that gastrin (G17) inhibits apoptosis of AR4-2J pancreatic adenocarcinoma cells, through the activation of Akt. We dissected the mechanisms responsible for this effect. D2, a CCKB receptor antagonist, inhibited G17 induction of Akt phosphorylation, measured by Western blots with anti-phospho-Akt antibodies. The intracellular calcium chelator BAPTA-AM, but not the PKC inhibitor GF109203X, blocked G17 induction of Akt. G17 stimulated BAD phosphorylation, measured by both Western blots with anti-phospho-BAD antibodies and by in vitro Akt kinase assays using recombinant BAD as substrate. G17 also induced FOXO3 phosphorylation assessed by Western blots with anti-phospho-FOXO3 antibodies, and BAPTA-AM inhibited this effect. Gastrin inhibited luciferase activity in cells transfected with FOXO1 together with a vector containing insulin-responsive sequences upstream of the luciferase reporter gene. In conclusion, G17 induces Akt through activation of CCKB receptors and of intracellular calcium-dependent, PKC-independent, pathways. This effect leads to BAD phosphorylation and to forkhead transcription factors inactivation.

The Akt and MAPK signal-transduction pathways regulate growth factor actions in isolated gastric parietal cells.

BACKGROUND & AIMS: Incubation of purified (>95%) canine parietal cells in primary culture with epidermal growth factor for 7-16 hours stimulates H(+)K(+)-adenosine triphosphatase gene expression. In this study, we examined the effect of prolonged stimulation (72 hours) of the parietal cells with epidermal growth factor. METHODS: H(+)K(+)-adenosine triphosphatase protein and gene expression were assessed by immunohistochemistry and Northern blots. Mitogen-activated protein kinase and Akt activation were quantitated by kinase assays and Western blots with specific antiphospho antibodies. Akt overexpression was achieved by adenovirus-mediated gene transfer of a constitutively active Akt gene. RESULTS: Epidermal growth factor changed the morphology of the cultured cells, which acquired the appearance of fusiform cells, and it inhibited H(+)K(+)-adenosine triphosphatase gene expression. Staining of the cells both with anti-H(+)K(+)-adenosine triphosphatase antibodies and with Texas Red-labeled Dolichos biflorus lectin confirmed that the fusiform cells expressed markers of parietal cell differentiation. Epidermal growth factor stimulated mitogen-activated protein kinase with 2 peaks of activation, observed after 5 minutes and 72 hours, whereas it activated Akt after 5 minutes but not 72 hours of incubation. Overexpression of Akt blocked both epidermal growth factor-induced morphological transformation and inhibition of H + K + -adenosine triphosphatase gene expression. Identical results were observed in the presence of the mitogen-activated protein kinase inhibitor PD98059. CONCLUSIONS: Activation of the Akt signal-transduction pathway seems to be a crucial event for the induction of parietal cell maturation and differentiation.

Regulation and function of COX-2 gene expression in isolated gastric parietal cells.

We examined expression, function, and regulation of the cyclooxygenase (COX)-2 gene in gastric parietal cells. COX-2-specific mRNA was isolated from purified (>95%) canine gastric parietal cells in primary culture and measured by Northern blots using a human COX-2 cDNA probe. Carbachol was the most potent inducer of COX-2 gene expression. Gastrin and histamine exhibited minor stimulatory effects. Carbachol-stimulated expression was inhibited by intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM (90%), protein kinase C (PKC) inhibitor GF-109203X (48%), and p38 kinase inhibitor SB-203580 (48%). Nuclear factor (NF)-kappaB inhibitor 1-pyrrolidinecarbodithioic acid inhibited carbachol-stimulated expression by 80%. Similar results were observed in the presence of adenoviral vector Ad.dom.neg.IkappaB, which expresses a repressor of NF-kappaB. Addition of SB-203580 with Ad.dom.neg.IkappaB almost completely blocked carbachol stimulation of COX-2 gene expression. We examined the effect of carbachol on PGE(2) release by enzyme-linked immunoassay. Carbachol induced PGE(2) release. Ad.dom.neg.IkappaB, alone or with SB-203580, produced, respectively, partial (70%) and almost complete (>80%) inhibition of carbachol-stimulated PGE(2) production. Selective COX-2 inhibitor NS-398 blocked carbachol-stimulated PGE(2) release without affecting basal PGE(2) production. In contrast, indomethacin inhibited both basal and carbachol-stimulated PGE(2) release. Carbachol induces COX-2 gene expression in the parietal cells through signaling pathways that involve intracellular Ca(2+), PKC, p38 kinase, and activation of NF-kappaB. The functional significance of these effects seems to be stimulation of PGE(2) release.

Role of small GTP binding proteins in the growth-promoting and antiapoptotic actions of gastrin.

G17 has growth promoting and antiapoptotic effects on the AR4-2J pancreatic acinar cell line. We previously reported that whereas MAPK regulates G17-stimulation of AR4-2J cell proliferation, Akt mediates the antiapoptotic action of G17. We examined the signal-transduction pathways mediating G17 stimulation of AR4-2J cell growth and survival. G17 activated the small GTP binding proteins Ras, Rac, Rho, and Cdc42. Transduction of the cells with adenoviral vectors expressing dominant negative Akt, Ras, Rho, and Cdc42 but not dominant negative Rac inhibited AR4-2J cell proliferation and survival. Both exoenzyme C3 from Clostridium botulinum (C3), a toxin known to inactivate Rho, and PD98059, a MAPK inhibitor, reversed G17 inhibition of AR4-2J cell apoptosis. G17 induction of Akt activation was reduced by >60% by both dominant negative Ras and Rho and by 30% by dominant negative Cdc42. In contrast, G17-stimulated MAPK activation was blocked by >80% by dominant negative Ras but not by dominant negative Rho and Cdc42. Similar results were observed in the presence of C3. Dominant negative Rac failed to affect G17 induction of both Akt and MAPK, whereas it inhibited sorbitol by almost 50% but not G17-stimulated activation of p38 kinase. Thus G17 promotes AR4-2J cell growth and survival through the activation of multiple GTP binding proteins, which, in turn, regulate different protein kinase cascades. Whereas Ras activates Akt and MAPK, Rho and Cdc42 appear to regulate Akt and possibly other as yet unidentified kinases mediating the growth-stimulatory actions of G17.