An investigation on influential factors of patient-controlled epidural analgesic requirement over time for upper abdominal surgeries

Abstract Background: Patient-controlled epidural analgesia (PCEA) is commonly used to relieve postoperative pain for upper abdominal surgeries. However, there is still a lack of studies exploring factors associated with PCEA consumption over time after upper abdominal surgery; our study intended to provide further elucidation about this issue. Methods: This study retrospectively evaluated postoperative PCEA consumption over time after upper abdominal surgery. Cumulative PCEA consumption in the first four 12-hour intervals was directly retrieved from the data recorded by infusion pumps. Potentially influential factors of PCEA requirements, including demographic variables and infusion pump settings, were also collected. A linear mixed model was applied to investigate the relationships between these factors and PCEA consumption over time. A backward elimination strategy was used to select independent factors significantly associated with PCEA consumption. Results: A total of 1001 patients were included in the analysis. On average, PCEA consumption after upper abdominal surgery peaked during the 2 nd 12-hour interval and then decreased gradually over time. After the model selection processes were completed, four independent factors were identified to have significant effects on PCEA consumption. Surgery for malignant disease and background infusion rate were positively associated with PCEA consumption and did not interact with time. Additionally, female patients tended to consume less and less PCEA over time relative to males. Age had a negative effect on PCEA consumption, which peaked during the 2 nd 12-hour interval and then decreased gradually over time. The final selected model exhibited acceptable predictive power relative to the observed data. Conclusion: Our analyses provided valuable information about the factors associated with PCEA consumption over time after upper abdominal surgery. However, the mechanism of how these factors interact over the course of time awaits further investigation

Increased requirement for minute ventilation and negative arterial to end-tidal carbon dioxide gradient may indicate malignant hyperthermia

Abstract Characteristic signs of malignant hyperthermia (MH) include unexplained tachycardia, increased end-tidal carbon dioxide (EtCO 2 ) concentration, metabolic and respiratory acidosis, and an increase in body temperature above 38.8 C. We present the case of a patient with highly probable MH. In addition to sinus tachycardia and metabolic and respiratory acidosis, this patient also had a negative arterial to EtCO 2 gradient and an increased requirement for minute ventilation to maintain a normal EtCO 2 concentration, with signs of increased CO 2 production. Despite these signs of MH, the patient's rectal temperature monitoring equipment did not show an increase in temperature, although the temperature measured in the mouth was increased. This case illustrates the unreliability of measuring rectal temperature as a means of reflecting body temperature during MH and the usefulness of increased CO 2 production signs in helping to diagnose MH

The Development of Perioperative Practices for Liver Transplantation: Advances and Current Trends

Transplantation is a young medical specialty that has grown rapidly over the past 50 years. Anesthesiologists, surgeons and hepatologists are all essential partners in the process of determining patient outcome. Each specialty has made landmark improvements in patient outcome. However, there is still variability in practice patterns in each of the 3 major specialties. This review will use a historic perspective to explore the unique forces that shaped specific transplant practices and those that gave rise to differences in perioperative practices. Anesthesiologists and surgeons have made significant improvements in the management of blood loss, and coagulation monitoring and intervention. This has improved operative survival and early patient outcome. Perioperative survival has improved despite a worldwide shortage of donor organs and a trend to transplant sicker patients. A smaller pool of donor organs is required to meet the needs of an expanding waiting list. The innovations to reduce deaths on the transplant wait list are reviewed along with their impact on overall patient outcome. The evolving organ shortage is the pinnacle point in shaping future transplant practices. Currently, institutional-specific practices may be reinforced by the informal “tutorship” that is used to train physicians and by the resources available at each site of practice. However, there is evidence that specific intraoperative practices such as the use of a low central venous pressure, selection of vasopressors and certain surgical techniques can modify patient outcome. Further investigation is needed to determine whether the good or the bad associated with each practice prevails and in what unique circumstance

Cardiovascular Dysfunction in Patients with End-stage Liver Disease

Most patients with advanced liver disease have a normal or even supernormal ejection fraction judged by echocardiogra-phy. Thus, physicians previously assumed that cardiac function was normal in most patients with liver disease. However, further investigation has uncovered multiple problems in cardiac performance that place patients at risk of heart failure. Patients with liver disease have defects in both systolic and diastolic function that only become obvious with physiologic stress such as liver transplantation. In addition there are additional defects in the electromechanical coupling of the heart that can have significant clinical consequences. These collective pathologic changes are termed “cirrhotic cardiomyopathy” and occur to some degree in all patients with liver disease. This review will explore the pathophysiology of cardiovascular changes in patients with end-stage liver disease

Cardiac evaluation of liver transplant candidates

Physicians previously thought that heart disease was rare in patients with end stage liver disease. However, recent evidence shows that the prevalence of ischemic heart disease and cardiomyopathy is increased in transplant candidates compared to most other surgical candidates. Investigators estimate that up to 26% of all liver transplant candidates have at least one critical coronary artery stenosis and that at least half of these patients will die perioperatively of cardiac complications. Cardiomyopathy also occurs in greater frequency. While all patients with advanced cardiac disease have defects in cardiac performance, a larger than expected number of patients have classical findings of dilated, restrictive and hypertrophic cardiomyopathy. This may explain why up to 56% of patients suffer from hypoxemia due to pulmonary edema following transplant surgery. There is considerable controversy on how to screen transplant candidates for the presence of heart disease. Questions focus upon, which patients should be screened and what tests should be used. This review examines screening strategies for transplant candidates and details the prognostic value of common tests used to identify ischemic heart disease. We also review the physiological consequences of cardiomyopathy in transplant candidates and explore the specific syndrome of “cirrhotic cardiomyopathy”

In vivo images of the epidural space with two- and three-dimensional optical coherence tomography in a porcine model.

BACKGROUND:No reports exist concerning in vivo optical coherence tomography visualization of the epidural space and the blood patch process in the epidural space. In this study, we produced real-time two-dimensional and reconstructed three-dimensional images of the epidural space by using optical coherence tomography in a porcine model. We also aimed to produce three-dimensional optical coherence tomography images of the dura puncture and blood patch process. METHODS:Two-dimensional and three-dimensional optical coherence tomography images were obtained using a swept source optical coherence tomography (SSOCT) system. Four laboratory pigs were intubated and ventilated after the induction of general anesthesia. An 18-gauge Tuohy needle was used as a tunnel for the optical coherence tomography probe to the epidural space. Two-dimensional and three-dimensional reconstruction optical coherence tomography images of the epidural space were acquired in four stages. RESULTS:In stage 1, real-time two-dimensional and reconstructed three-dimensional optical coherence tomography of the lumbar and thoracic epidural space were successfully acquired. In stage 2, the epidural catheter in the epidural space was successfully traced in the 3D optical coherence tomography images. In stage 3, water injection and lumbar puncture were successfully monitored in all study animals. In stage 4, 10 mL of fresh blood was injected into the epidural space and two-dimensional and three-dimensional optical coherence tomography images were successfully acquired. CONCLUSIONS:These animal experiments suggest the potential capability of using an optical coherence tomography-based imaging needle in the directed two-dimensional and three-dimensional visualization of the epidural space. More investigations involving humans are required before optical coherence tomography can be recommended for routine use. However, three-dimensional optical coherence tomography may provide a novel, minimally invasive, and safe way to observe the spinal epidural space, epidural catheter, lumbar puncture hole, and blood patch

An investigation on influential factors of patient-controlled epidural analgesic requirement over time for upper abdominal surgeries

Background: Patient-controlled epidural analgesia (PCEA) is commonly used to relieve postoperative pain for upper abdominal surgeries. However, there is still a lack of studies exploring factors associated with PCEA consumption over time after upper abdominal surgery; our study intended to provide further elucidation about this issue. Methods: This study retrospectively evaluated postoperative PCEA consumption over time after upper abdominal surgery. Cumulative PCEA consumption in the first four 12-hour intervals was directly retrieved from the data recorded by infusion pumps. Potentially influential factors of PCEA requirements, including demographic variables and infusion pump settings, were also collected. A linear mixed model was applied to investigate the relationships between these factors and PCEA consumption over time. A backward elimination strategy was used to select independent factors significantly associated with PCEA consumption. Results: A total of 1001 patients were included in the analysis. On average, PCEA consumption after upper abdominal surgery peaked during the 2nd 12-hour interval and then decreased gradually over time. After the model selection processes were completed, four independent factors were identified to have significant effects on PCEA consumption. Surgery for malignant disease and background infusion rate were positively associated with PCEA consumption and did not interact with time. Additionally, female patients tended to consume less and less PCEA over time relative to males. Age had a negative effect on PCEA consumption, which peaked during the 2nd 12-hour interval and then decreased gradually over time. The final selected model exhibited acceptable predictive power relative to the observed data. Conclusion: Our analyses provided valuable information about the factors associated with PCEA consumption over time after upper abdominal surgery. However, the mechanism of how these factors interact over the course of time awaits further investigation