복잡계에서의 하이브리드 상전이

학위논문(박사)--서울대학교 대학원 :자연과학대학 물리학과,2020. 2. 강병남.Complex organization of elements can bring in new phases and novel critical effects. The phase transition of a complex system can be rich and unique. More is different, and details matter. In particular, complexification may yield hybrid phase transition, a discontinuous transition which accompanies critical phenomena. This novel type of phase transition has been discovered across diverse complex systems, including k-core percolation, cascade failures of interdependent networks, generalized epidemic spreading, restricted percolation, Kuramoto oscillators with flat-topped frequency distribution, and restricted synchronization. In this dissertation, it is investigated that how a complex system exhibits a discontinuous jump of the order parameter together with the critical phenomena at the same transition point. In particular, hybrid percolation transition and hybrid synchronization transition are focused. Several universal (or potentially universal) mechanisms are noticed. There are hybrid percolation transitions of cascade class and of merging class, hybrid synchronization transitions of Kuramoto models with flat natural frequency distribution and of restricted Kuramoto model with ranking-based shuffling dynamics. Hybrid phase transitions of complex systems may be classified on the basis of those mechanisms.복잡계(complex system)는 복잡하고 어렵다는 의미보다는 복합적이라는 의미에서 바라보아야 한다. 계를 구성하는 요소가 여러 종류이거나 복합적인 상호작용이 있는 경우 단일 종 사이의 단순한 상호작용에서는 볼 수 없는 복합적인 효과가 나타날 수 있다. 복잡계 네트워크는 계를 구성하는 요소(노드)들과 복합적 상호작용의 연결 관계(링크)에 대한 수학적인 표현 방법이다. 어떤 복잡계가 특정한 기능을 하는지 여부는 전체적인 연결망의 상태와 더불어 내부 상호작용의 방식과도 관련될 수 있다. 상전이는 계의 기능 여부와 같은 어떤 질적인 변화를 기술한다. 여과 상전이(percolation phase transition)와 동기화 상전이(synchronization phase transition)는 복잡계에서 연구되는 대표적인 상전이이다. 여과 상전이는 전체적인 연결이 없는 상태에서 전체적인 연결이 있는 상태로의 네트워크의 구조적 변화다. 한편 동기화 상전이는 시스템의 운동에서 나타나는, 결맞음성이 없는 무질서한 상태로부터 동기화된 상태로의 동역학적 변화다. 상전이는 연속 상전이와 불연속 상전이로 구분되는데, 두 개의 상이 공존할 수 있는 불연속 상전이와 달리 연속 상전이에서는 임계점에서 두 개의 상이 하나로 합치된다. 이에 연속상전이의 임계점에서는 계 전체가 강한 상관관계에 있기 때문에 부분의 변화가 전체의 변화로 이어질 수 있고 임계현상이 나타난다. 불연속 상전이에서는 임계 현상이 있을 수도 있고 없을 수도 있다. 하이브리드 상전이(hybrid phase transition)란 연속상전이의 특징인 임계현상을 동반하는 불연속 상전이를 의미한다. 따라서 어떻게 불연속 상전이가 임계현상을 가질 수 있는가 하는 의문점이 생긴다. 본 학위 논문에서는 복잡계에서 나타나는 하이브리드 상전이와 그 메커니즘을 알아본다. 특히 하이브리드 여과 상전이(percolation hybrid transition)와 하이브리드 동기화 상전이(synchronization hybrid transition)를 중점적으로 살펴본다. 여과 상전이의 경우 연쇄 파급 과정(cascade process)과 클러스터 성장 과정(merging process)에서 각기 다른 종류의 하이브리드 상전이가 일어난다. 구라모토 진동자들의 동기화 상전이에서는 고유진동수의 분포에 따라 연속, 불연속, 하이브리드 상전이가 가능한데, 하이브리드 상전이는 분포가 납작해지는 경우에 발생한다. 또한 어떤 순위(ranking)에 따라 두 개의 그룹으로 나뉘어 제한된 상호작용을 하는 경우에도 하이브리드 동기화 상전이가 가능하다. 특히 이러한 메커니즘은 여러 모형에서 보편적(universal)으로 나타나기도 하는데, 이를 바탕으로 비평형 복잡계에서의 하이브리드 상전이를 분류해 볼 수 있다.1 Introduction 1 1.1 What is a hybrid phase transition 1 1.2 A critical singularity at the discontinuous transition 4 1.3 Hybrid phase transition of equilibrium complex systems 6 1.3.1 Ashkin-Teller magnet on scale-free network 7 1.3.2 Spin chain under long range interaction 8 1.3.3 Colloidal metamagnet 9 1.4 Structure and goal of this dissertation 10 2 Hybrid percolation transition 13 2.1 The theory of continuous percolation transition 13 2.1.1 Fortuin-Kasteleyn mapping to magnetic system 14 2.1.2 Critical phenomena of the percolation phase transition 15 2.2 Erdos–Renyi model 18 2.2.1 The original random network model 18 2.2.2 Random graph process 19 2.2.3 Random cluster aggregation process 23 2.3 Search for a discontinuous percolation transition 26 2.4 Hybrid percolation transition 27 2.4.1 k-core percolation 27 2.4.2 Hybrid percolation transition induced by prunning process 28 2.4.3 Hybrid percolation transition induced by cluster merging process 31 2.4.4 Restricted Erdos–Renyi model 31 2.4.5 Two diverging length scales of the hybrid percolation transition 36 3 Inter-event time, burst and hybrid percolation transition 39 3.1 Introduction 39 3.2 Results 42 3.3 Analytic calculation of interevent time distribution 47 3.4 Summary 49 4 Synchronization 51 4.1 Kuramoto model 51 4.2 Synchronization phase transition 52 4.3 The mean field theory of Kuramoto 54 4.4 Remarks on self-consistency method and exact theories 56 5 Hybrid synchronization transition 59 5.1 From Lorentzian to uniform 59 5.2 Uniform 61 5.3 Lorentzian vs uniform : clustering picture 63 5.4 Flat top with tails appended 63 5.5 Any hybrid critical phenomena 68 5.6 Explosive synchronization and hybrid synchronization 71 5.7 Jump mechanisms of explosive synchronization and hybrid synchronization 74 6 Competing Kuramoto model 77 6.1 Mixed signs of couplings 77 6.2 Hybrid phase transition of actively competing model 80 6.2.1 Emergence of the mean angular speed 83 6.2.2 Self-consistency equation 84 6.2.3 Incoherent and pi solutions 85 6.2.4 The self-consistency solution for incoherent and pi states 85 6.2.5 Supercritical hybrid phase transition 86 6.2.6 Subcritical hybrid bifurcation 89 6.2.7 Phase diagram involves three phases 92 6.2.8 Linear stability of the self-consistency solutions 92 6.2.9 Metastable state en route to traveling-wave synchronization state 94 6.2.10 A potential application to brain 98 6.2.11 Summary 99 6.3 Hybrid phase transition of passively competing model 99 6.3.1 Uniform 100 6.3.2 Lorentzian 105 6.4 An avalanche of frequency splittings: a hybrid critical phenomenon 107 6.5 Remarks on the Ott-Antonsen method 110 6.6 Summary 111 7 The restricted Kuramoto model 113 7.1 model 115 7.2 self consistency equation 116 7.3 Results and discussions 117 8 Conclusion 127 Appendices 129 Appendix A Kasteleyn-Fortuin Transformation 131 Appendix B Ott-Antonsen and Watanabe-Strogatz reductions 133 Appendix C Temporal fluctuations of the Kuramoto order parameter 141 Appendix D Useful integrals 145 Appendix E Numerical Tips 149 Bibliography 153 Abstract in Korean 167Docto

Volume-Controlled Versus Dual-Controlled Ventilation during Robot-Assisted Laparoscopic Prostatectomy with Steep Trendelenburg Position: A Randomized-Controlled Trial

Dual-controlled ventilation (DCV) combines the advantages of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Carbon dioxide (CO2) pneumoperitoneum and steep Trendelenburg positioning for robot-assisted laparoscopic radical prostatectomy (RALRP) has negative effects on the respiratory system. We hypothesized that the use of autoflow as one type of DCV can reduce these effects during RALRP. Eighty patients undergoing RALRP were randomly assigned to receive VCV or DCV. Arterial oxygen tension (PaO2) as the primary outcome, respiratory and hemodynamic data, and postoperative fever rates were compared at four time points: 10 min after anesthesia induction (T1), 30 and 60 min after the initiation of CO2 pneumoperitoneum and Trendelenburg positioning (T2 and T3), and 10 min after supine positioning (T4). There were no significant differences in PaO2 between the two groups. Mean peak airway pressure (Ppeak) was significantly lower in group DCV than in group VCV at T2 (mean difference, 5.0 cm H2O; adjusted p < 0.001) and T3 (mean difference, 3.9 cm H2O; adjusted p < 0.001). Postoperative fever occurring within the first 2 days after surgery was more common in group VCV (12%) than in group DCV (3%) (p = 0.022). Compared with VCV, DCV did not improve oxygenation during RALRP. However, DCV significantly decreased Ppeak without hemodynamic instability.ope

공기업 경영성과와 경영진 보상 간 관계

학위논문 (석사)-- 서울대학교 대학원 : 행정대학원 행정학과, 2018. 2. 금현섭.탈전통관료제의 신공공관리론(NPM)과 정부 재창조론(Reinventing government theory)이 등장하면서 공적 영역에서도 성과 개념이 도입되었다. 우리나라에서도 1983년 정부투자관리기관관리기본법 제정 이후 경영평가제도로 공기업 운영의 성과평가가 이루어지고 있다. 그동안 경영평가 제도가 35년간 공공기관의 경영관리의 핵심적 평가정책수단으로 활용되어 왔으며 이러한 평가결과로 경영진 보상이 결정된다. 성과에 대한 가중치를 달리하여 공기업의 성과평가결과는 성과급으로 이어지고 이 성과급과 기본연봉의 합인 경영진의 총연봉이 결정되는데 본 연구에서는 공기업 성과에 연동한 경영진 보상이 적절히 반영되고 있는지를 분석해보고자 하였다. 공기업의 성과가 경영진 연봉에 어떻게 연동되는가?에 대한 연구 질문을 규명하고 공기업의 재무성과(수익성), 경영효율성과(효율성), 국민체감도(공공성)가 경영진의 연봉에 영향을 미칠 때, 정부개입과 관련된 통제변수들이 투입되었을 때 성과가 어떻게 연봉에 연동되는지를 확인하기 위하여 최근 4개년도(2012-16년) 패널데이터를 수집해 통계적 기법의 실증 분석을 실시하였다. 재무성과는 수익성을, 경영효율성과는 효율성, 국민체감도는 공공성을 대표하는 변수로 조작화하여 측정하였다. 경영평가제도에서 각각의 가중치를 연도별로 상이하게 놓고 공공기관 및 공기업에 대해 다양한 항목들을 평가하고 있지만 본 연구에서는 각기 상이한 가중치들을 세 가지 수익성, 효율성, 공공성 측면에서의 성과들이 경영진 연봉에 어떻게 연동되어 있는지, 그 연동성 크기에 초점을 맞추었다. 분석결과 재무성과, 경영효율성과, 국민체감도 성과 변수는 상임기관장의 재무성과만 제외하면 경영진 총연봉에 통계적으로 유의미한 정(+)의 관계를 가졌다(모형 1). 반면 경영진 성과급에는 재무성과가 상임기관장, 상임이사, 상임감사 모두의 경우에서 유의미한 정(+)의 관계를 가지지 못했다(모형 1). 이는 통제변수를 고려하였을 때에도 재무성과는 상임감사의 경우에서만 유의미한 정(+)의 관계로 나타났고, 경영효율성과만이 일정하게 모든 종속변수의 경우에서 유의미한 정(+)의 관계를 보였다(모형 2). 통제변수 중 등록규제가 상임이사의 경우에서만 유의미한 부(-)의 관계를 가지는 것으로 나타났고, 등록규제와 성과의 상호작용항을 만들어 회귀분석을 한 결과, 등록규제가 재무성과에 영향을 미쳐 상임이사의 총연봉과 성과급에 연동되어있음을 알 수 있었다(모형 2). 지배구조의 통제변수를 추가 투입하여 성과에 연동한 보상에 미치는 영향을 확인하였을 때, 경영진 총연봉과 성과급 모두에 대해 경영효율성과는 여전히 일관적으로 통계적으로 유의미한 정(+)의 관계를 가졌으나, 재무성과와 국민체감도 성과는 상임감사의 경우를 제외하고는 유의미한 정(+)의 관계를 가지지 않았다(모형 3). 결국 경영효율성과와 국민체감도 성과, 재무성과 순으로 경영진 연봉과 일관적으로 유의미한 정(+)의 관계를 가짐을 확인하였다. 이는 준․시장형 공기업들이 경영평가를 통한 성과급 수여와 이를 통해 총연봉이 결정되므로 상대적으로 성과를 올리기 쉬운 비계량적 경영효율성과 제고에 취중하고 있음을 추정해본다. 시장형, 준시장형 공기업임에도 재무적인 성과를 단기간에 가시적으로 끌어올리기 쉽지 않기 때문에 경영진의 입장에서는 조직 내부의 경영 효율화 항목 점수를 높일 수 있는 방안을 경영진의 입장에서도 고려할 수밖에 없는 것이다. 이러한 비계량평가 성과가 경영진 보상에 연계된다는 것은 정성적 평가를 수치화한 기관의 경영효율화 부분으로 이루어진 성과 항목이므로 수익성이나 공공성 부분의 경영성과가 아닌 조직 내부의 효율화에 집중하고 있다는 것이다. 성과개념의 초점이 효율화에 맞추어진 것이 경영평가를 주관하는 정부와 기재부의 경영평가 목표와 부합한다면 현행의 평가제도가 순기능을 하고 있는 것이지만 수익성과 공공성 부문 역시 신공공관리론에서 주장하는 성과의 중요한 가치이므로 효율성 부문이 강조되고 있는 현행의 평가제도에 대해 이 점을 고려해볼 필요가 있다. 재무성과 보다 국민체감도 평가 성과에서 경영진 보상과 연동이 유의미한 정(+)의 관계를 가짐을 확인하였다. 국민체감도 평가는 고객만족도 평가와 함께 시행되는데 고객만족도 평가는 조직 차원에서 고객에게 만점에 가까운 점수를 유도하여 편향(bias)이 심하기 때문에 본 연구에서는 보다 공공성 측면을 나타낼 수 있는 신뢰성을 지닌 변수를 국민체감도 성과로 조작화하여 분석을 진행하였다. 이러한 점을 고려할 때, 분석 결과에서처럼 국민체감도 성과가 경영진 보상과 유의미한 관련성을 가지므로 공공기관을 대상으로 하는 경영평가에서 국민체감도 가중치를 보다 상향 조정하여 공공기관의 공공성 측면을 확대하는 것이 바람직하다고 본다.제 1 장 서론 1 제 1 절 연구의 배경 및 목적 1 제 2 장 이론적 논의와 선행연구의 검토 3 제 1 절 성과에 연동한 경영진의 보상 3 1. 경영자 보상 3 2. 대리인 이론 5 3. 성과와 보상 9 제 2 절 성과에 연동한 공기업 경영진의 보상 10 1. 신공공관리론 10 2. 성과와 보상 간 관계 12 제 3 절 정부 개입 정도와 성과에 연동한 공기업 경영진의 보상 14 1. 지배구조 14 2. 정부규제 17 제 4 절 연구대상 관련 현행 제도 19 1. 공기업 경영진 보상 체계 19 2. 공공기관 경영평가제도 21 3. 연구의 차별성 23 제 3 장 연구가설 및 연구방법 24 제 1 절 연구문제 및 연구가설 23 제 2 절 변수 및 변수의 조작화 28 1. 종속변수 28 2. 독립변수 29 3. 통제변수 30 4. 변수의 조작화 31 5. 통제변수 33 6. 변수의 조작화 33 제 4 장 분석결과 34 제 1 절 기술통계분석 34 1. 다중공선성 검정 34 2. 기술통계량 분석 38 제 2 절 다중회귀분석 43 1. 독립변수 투입에 따른 회귀모형 설명력 변화 43 2. 다중회귀분석 결과 44 제 5 장 결론 62 제 1 절 연구결과의 요약 62 제 2 절 연구의 정책적 시사점 65 제 3 절 연구의 한계 67 참고문헌 69 Abstract 74Maste

Comparison of Sufentanil- and Fentanyl-based Intravenous Patient-controlled Analgesia on Postoperative Nausea and Vomiting after Laparoscopic Nephrectomy: A Prospective, Double-blind, Randomized-controlled Trial

Background: The incidence of postoperative nausea and vomiting (PONV) remains high. The effects of sufentanil for PONV is not firmly confirmed. The aim of this study was to compare the effect of sufentanil- and fentanyl-based intravenous patient-controlled analgesia (IV-PCA) on the incidence of PONV after laparoscopic nephrectomy. Methods: Eighty-six patients were randomly allocated to receive either the sufentanil (n =43) or fentanyl (n =43). IV-PCA was prepared using either sufentanil 3 µg/kg or fentanyl 20 µg/kg, ramosetron 0.3 mg, and ketorolac 120 mg. The primary outcome of was the incidence of PONV during 24 h after post anesthesia care unit (PACU) discharge. The secondary outcomes were the modified Rhodes index and patient satisfaction scores at 24 h after PACU discharge, need for rescue antiemetics, pain score, need for additional analgesics, and cumulative consumption of IV-PCA Results: The incidence of PONV was comparable between the sufentanil and fentanyl groups (64.3% vs. 65%, p = 0.946; respectively). The number of patients who required antiemetics (p = 0.946) and the modified Rhodes index at 24 h after post-anesthesia care unit discharge (p = 0.668) were also comparable in both groups. No significant differences were found in the secondary outcomes, including the analgesic profiles and adverse events between the groups. Conclusions: In conclusion, sufentanil- and fentanyl-based IV-PCA showed similar incidence of PONV with comparable analgesic effects after laparoscopic nephrectomy. Based on these results, we suggest that sufentanil and fentanyl may provide comparable effects for IV-PCA after laparoscopic nephrectomy.ope

Evaluation of Informed Consent for Withholding and Withdrawal of Life Support in Korean Intensive Care Units

BACKGROUND: The goal of this study was to analyze the process and characteristics of withholding or withdrawal of life support (WLS) in Korean intensive care units (ICUs). METHODS: This was a single-centered retrospective analysis of patients who died in the ICUs of a tertiary hospital in Korea from January to December 2012. WLS informed consents and clinical data were analyzed. RESULTS: Of 285 deaths during the study period, informed consents for WLS were obtained from 228 patients (80.0%). All WLS decisions were made by family members after the patient's loss of decision-making capacity. Decisions were made most frequently by the patient's son (50.6%). Patients in the WLS group were older than those in the non-WLS group, and older age was associated with the WLS decision. Thirty-seven patients (16.2%) died within one hour of WLS approval, and 182 patients (79.8%) died on the day of WLS approval. The most frequently withheld life support modality was chest compression (100%), followed by defibrillation (95.9%) and pacemaker insertion (63.3%). CONCLUSIONS: Aggressive and invasive life support measures were those most frequently withheld or withdrawn by decision-makers in Korean ICUs. The most common proxy was the son, rather than the spouse.ope

Usefulness of Non-Invasive Cardiac Output Monitoring in Elderly Patients Undergoing Monopolar Transurethral Resection of the Prostate: A Pilot Study

Objective: To assess the impact of irrigating fluid on hemodynamic profiles using real-time non-invasive cardiac output monitoring (NICOM) in elderly patients undergoing monopolar transurethral resection of the prostate (TURP). Methods: Twenty patients between 65 and 80 years of age who were scheduled for monopolar TURP and received spinal anesthesia up to T10 were enrolled. Irrigating fluid (2.7% sorbitol with 0.5% mannitol solution) was used. Hemodynamic profiles including cardiac index, and stroke volume variation (SVV) using NICOM were obtained. Estimated irrigating fluid absorption was indirectly calculated. Results: The median amount of irrigating fluid used was 6000 mL. The median SVV was 11%, which increased to 12% at 10 minutes after initiating surgery. No significant changes in the cardiac index were observed. The estimated absorption of irrigating fluid was almost zero. Conclusions: Although the estimated amount of irrigating fluid that was absorbed was negligible, the increase in SVV may indicate intravascular volume depletion with diuresis resulting from mannitol in the irrigating fluid early during irrigation. Therefore, even during short irrigating times, intensive hemodynamic monitoring should be performed to monitor the possibility of intravascular volume depletion as well as volume overload, especially immediately after large amounts of irrigating fluid are used.ope

Efficacy of Palonosetron vs. Ramosetron for the Prevention of Postoperative Nausea and Vomiting: A Meta-Analysis of Randomized Controlled Trials.

PURPOSE: This study was designed as a meta-analysis of randomized controlled trials (RCTs) that included the comparison of palonosetron and ramosetron for postoperative nausea and vomiting (PONV) prophylaxis. MATERIALS AND METHODS: A systematic search was conducted for the PubMed, EMBASE, Web of Science, CENTRAL, KoreaMed, and Google Scholar databases (PROSPERO protocol number CRD42015026009). Primary outcomes were the incidences of postoperative nausea (PON) and postoperative vomiting (POV) during the first 48 hrs after surgery. The total 48-hr period was further analyzed in time epochs of 0-6 hrs (early), 6-24 hrs (late), and 24-48 hrs (delayed). Subgroup analyses according to number of risk factors, sex, and type of surgery were also performed. RESULTS: Eleven studies including 1373 patients were analyzed. There was no difference in PON or POV between the two drugs for the total 48-hr period after surgery. However, palonosetron was more effective in preventing POV during the delayed period overall [relative risk (RR), 0.59; 95% confidence interval (CI), 0.39 to 0.89; p=0.013], as well as after subgroup analyses for females and laparoscopies (RR, 0.56; 95% CI, 0.36 to 0.86; p=0.009 and RR, 0.46; 95% CI, 0.23 to 0.94; p=0.033). Subgroup analysis for spine surgery showed that ramosetron was more effective in reducing POV during the total 48-hr (RR, 3.34; 95% CI, 1.46 to 7.63; p=0.004) and early periods (RR, 8.47; 95% CI, 1.57 to 45.72; p=0.013). CONCLUSION: This meta-analysis discovered no definite difference in PONV prevention between the two drugs. The significant findings that were seen in different time epochs and subgroup analyses should be confirmed in future RCTs.ope

Effects of Post Ischemia-Reperfusion Treatment with Trimetazidine on Renal Injury in Rats: Insights on Delayed Renal Fibrosis Progression

Even after recovery from acute kidney injury, glomeruli remain vulnerable to further injury by way of interstitial fibrosis. This study is aimed at elucidating the effects of post ischemia-reperfusion (I/R) treatment with trimetazidine on the progression to renal fibrosis as well as short- and intermediate-term aspects. Trimetazidine 3 mg/kg or 0.9% saline was given intraperitoneally once upon reperfusion or daily thereafter for 5 d or 8 w. Renal histologic changes and related signaling proteins were assessed. After 24 h, post I/R treatment with trimetazidine significantly reduced serum blood urea nitrogen and creatinine levels and tubular injury accompanied with upregulation of hypoxia-inducible factor- (HIF-) 1α, vascular endothelial growth factor (VEGF), and Bcl-2 expression. After 5 d, post I/R treatment with trimetazidine reduced renal tubular cell necrosis and apoptosis with upregulation of HIF-1α-VEGF and tissue inhibitors of metalloproteinase activities, attenuation of matrix metalloproteinase activities, and alteration of the ratio of Bax to Bcl-2 levels. After 8 w, however, post I/R treatment with trimetazidine did not modify the progression of renal fibrosis. In conclusion, post I/R treatment with trimetazidine allows ischemic kidneys to regain renal function and structure more rapidly compared to nontreated kidneys, but not enough to resolute renal fibrosis in long-term aspect.ope

Comparisons of Pressure-controlled Ventilation with Volume Guarantee and Volume-controlled 1:1 Equal Ratio Ventilation on Oxygenation and Respiratory Mechanics during Robot-assisted Laparoscopic Radical Prostatectomy: a Randomized-controlled Trial

Background: During robot-assisted laparoscopic radical prostatectomy (RALP), steep Trendelenburg position and carbon dioxide pneumoperitoneum are inevitable for surgical exposure, both of which can impair cardiopulmonary function. This study was aimed to compare the effects of pressure-controlled ventilation with volume guarantee (PCV with VG) and 1:1 equal ratio ventilation (ERV) on oxygenation, respiratory mechanics and hemodynamics during RALP. Methods: Eighty patients scheduled for RALP were randomly allocated to either the PCV with VG or ERV group. After anesthesia induction, volume-controlled ventilation (VCV) was applied with an inspiratory to expiratory (I/E) ratio of 1:2. Immediately after pneumoperitoneum and Trendelenburg positioning, VCV with I/E ratio of 1:1 (ERV group) or PCV with VG using Autoflow mode (PCV with VG group) was initiated. At the end of Trendelenburg position, VCV with I/E ratio of 1:2 was resumed. Analysis of arterial blood gases, respiratory mechanics, and hemodynamics were compared between groups at four times: 10 min after anesthesia induction (T1), 30 and 60 min after pneumoperitoneum and Trendelenburg positioning (T2 and T3), and 10 min after desufflation and resuming the supine position (T4). Results: There were no significant differences in arterial blood gas analyses including arterial oxygen tension (PaO2) between groups throughout the study period. Mean airway pressure (Pmean) were significantly higher in the ERV group than in the PCV with VG group T2 (p<0.001) and T3 (p=0.002). Peak airway pressure and hemodynamic data were comparable in both groups. Conclusion: PCV with VG was an acceptable alternative to ERV during RALP producing similar PaO2 values. The lower Pmean with PCV with VG suggests that it may be preferable in patients with reduced cardiovascular function.ope

Association between 20% Albumin Use and Acute Kidney Injury in Major Abdominal Surgery with Transfusion

Red blood cell (RBC) transfusion and albumin administration can affect kidney function. We aimed to evaluate the association between intraoperative 20% albumin administration and acute kidney injury (AKI), along with the duration of hospitalization and 30-day mortality in patients undergoing major abdominal surgery with RBC transfusion. This retrospective study included 2408 patients who received transfusions during major abdominal surgery. Patients were categorized into albumin (n = 842) or no-albumin (n = 1566) groups. We applied inverse probability of treatment weighting (IPTW), propensity score (PS) matching (PSM), and PS covariate adjustment to assess the effect of albumin administration on the outcomes. In the unadjusted cohort, albumin administration was significantly associated with increased risk of AKI, prolonged hospitalization, and higher 30-day mortality. However, there was no significant association between albumin administration and AKI after adjustment (OR 1.26, 95% CI 0.90-1.76 for the IPTW; OR 1.03, 95% CI 0.72-1.48 for the PSM; and OR 1.04, 95% CI 0.76-1.43 for the PS covariate adjustment methods). While albumin exposure remained associated with prolonged hospitalization after adjustment, it did not affect 30-day mortality. Our findings suggest that hyper-oncotic albumin can be safely administered to patients who are at risk of developing AKI due to RBC transfusion.ope