Hagen Bomberg

Aortic root and cusp configuration determine aortic valve function

OBJECTIVE Normalisation of aortic root and cusp configuration is a prerequisite for successful aortic valve repair (AVR). Using transthoracic echocardiography, we studied aortic root dimensions relative to body size in normal subjects and AVR patients. METHODS Aortic roots of healthy volunteers (n=130, age 27.9 ± 16.9 years) were examined for aortoventricular (AV), sinus (S), sinutubular-junction diameters (ST) and effective height (height difference between the AV plane and central coaptation point, eH) by transthoracic echocardiography. In 651 patients, after AVR residual aortic valve insufficiency (AI) and eH were determined. The relationships between eH versus root dimensions and eH versus residual AI were analysed by analysis of variance with Bonferroni post hoc testing. RESULTS Root dimensions correlated with each other and body size (r=0.74-0.91). In addition, a correlation between AV (r=0.73), sinus diameter (r=0.76), body height (r=0.77), body surface area (r=0.81) and eH was found. After AVR, eH was 9.8 ± 0.9 mm in 235 patients without postoperative AI, 9.4 ± 1.1mm in 370 with mild AI, 7.9 ± 1.4mm in 43 patients with moderate AI and 6 ± 1mm in three patients with severe AI. The difference in means of effective height between the groups was significant (p<0.005). Of 497 AVR patients with an eH ≥ 9 mm, 309 had no or trivial AI, 186 had mild AI and only two had moderate AI. CONCLUSIONS Parameters of aortic root dimensions follow a seemingly constant pattern in humans of different sizes. Effective height has a constant relationship to root dimensions and body size. In AVR, normalisation of eH leads to a high probability of normal or near-normal aortic valve function.

Risk factors for nonocclusive mesenteric ischemia after elective cardiac surgery.

OBJECTIVE Nonocclusive mesenteric ischemia (NOMI) may occur after cardiopulmonary bypass. It is crucial to early identify patients who are at risk of developing this complication. The aim of this prospective study was to evaluate perioperative risk factors in a large cohort of patients undergoing elective cardiac surgery. METHODS From January 1, 2010, to March 31, 2011, all patients scheduled for elective cardiac surgery were screened for participation in this trial. If NOMI was suspected, arterial angiography was performed. NOMI and non-NOMI patients were compared with respect to all variables assessed in this study. Additionally, odds ratios were calculated. Linear discriminant analyses as well as logistic regression analyses were performed to develop a model that identifies patients at risk for developing NOMI. RESULTS Eight hundred sixty-five patients were included in the study, of whom 78 developed NOMI. Among preoperative parameters, renal insufficiency, diuretic therapy, and age >70 years showed the highest odds ratios for postoperative NOMI. The highest odds ratios for development of NOMI were observed with postoperative variables. In particular, the need for intra-aortic balloon pump support and serum lactate concentrations >5 mmol/L proved to be serious risk factors. Using a linear discriminant analysis with 7 variables, 92.3% of patients were correctly classified (sensitivity 76.9%, specificity 93.8%). CONCLUSIONS A high index of suspicion for NOMI in patients with the above-mentioned risk factors may decrease the diagnostic and therapeutic delay. To identify at-risk patients the developed risk equation is a useful tool with a high specificity.

Survival after long-term isoflurane sedation as opposed to intravenous sedation in critically ill surgical patients: Retrospective analysis.

BACKGROUND Isoflurane has shown better control of intensive care sedation than propofol or midazolam and seems to be a useful alternative. However, its effect on survival remains unclear. OBJECTIVE The objective of this study is to compare mortality after sedation with either isoflurane or propofol/midazolam. DESIGN A retrospective analysis of data in a hospital database for a cohort of consecutive patients. SETTING Sixteen-bed interdisciplinary surgical ICU of a German university hospital. PATIENTS Consecutive cohort of 369 critically ill surgical patients defined within the database of the hospital information system. All patients were continuously ventilated and sedated for more than 96 h between 1 January 2005 and 31 December 2010. After excluding 169 patients (93 >79 years old, 10 <40 years old, 46 mixed sedation, 20 lost to follow-up), 200 patients were studied, 72 after isoflurane and 128 after propofol/midazolam. INTERVENTIONS Sedation with isoflurane using the AnaConDa system compared with intravenous sedation with propofol or midazolam. MAIN OUTCOME MEASURES Hospital mortality (primary) and 365-day mortality (secondary) were compared with the Kaplan–Meier analysis and a log-rank test. Adjusted odds ratios (ORs) [with 95% confidence interval (95% CI)] were calculated by logistic regression analyses to determine the risk of death after isoflurane sedation. RESULTS After sedation with isoflurane, the in-hospital mortality and 365-day mortality were significantly lower than after propofol/midazolam sedation: 40 versus 63% (P = 0.005) and 50 versus 70% (P = 0.013), respectively. After adjustment for potential confounders (coronary heart disease, chronic obstructive pulmonary disease, acute renal failure, creatinine, age and Simplified Acute Physiology Score II), patients after isoflurane were at a lower risk of death during their hospital stay (OR 0.35; 95% CI 0.18 to 0.68, P = 0.002) and within the first 365 days (OR 0.41; 95% CI 0.21 to 0.81, P = 0.010). CONCLUSION Compared with propofol/midazolam sedation, long-term sedation with isoflurane seems to be well tolerated in this group of critically ill patients after surgery.

A novel device for target controlled administration and reflection of desflurane – the Mirus™

The Anaconda™ system is used to deliver inhalational sedation in the intensive care unit in mainland Europe. The new Mirus™ system also uses a reflector like the Anaconda; however, it also identifies end‐tidal concentrations from the gas flow, injects anaesthetics during early inspiration, controls anaesthetic concentrations automatically, and can be used with desflurane, which is not possible using the Anaconda. We tested the Mirus with desflurane in the laboratory. Compared with an external gas monitor, the bias (two standard deviations) of the end‐tidal concentration was 0.11 (0.29)% volume. In addition, automatic control was reasonable and maximum concentration delivered was 10.2%, which was deemed to be sufficient for clinical use. Efficiency was > 80% and was also deemed to be acceptable, but only when delivering a low concentration of desflurane (≤ 1.8%). By modifying the reflector, we improved efficiency up to a concentration of 3.6%. The Mirus appears to be a promising new device for long‐term sedation with desflurane on the intensive care unit, but efficiency must be improved before routine clinical use becomes affordable.

Endothelin and vasopressin influence splanchnic blood flow distribution during and after cardiopulmonary bypass

OBJECTIVE Gastrointestinal blood flow can be compromised during and after cardiopulmonary bypass. Endothelin has been shown to be involved in the intestinal microcirculatory disturbance of sepsis. The aim of the present study was to analyze the involvement of the endothelin system on intestinal blood flow regulation during cardiopulmonary bypass and the effect of vasopressin given during cardiopulmonary bypass. METHODS A total of 24 pigs were studied in 4 groups (n = 6): group I, sham; group II, ischemia/reperfusion with 1 hour of superior mesenteric artery occlusion; group III, cardiopulmonary bypass for 1 hour; and group IV, 1 hour of cardiopulmonary bypass plus vasopressin administration, maintaining the baseline arterial pressure. All the pigs were reperfused for 90 minutes. During the experiment, the hemodynamics and jejunal microcirculation were measured continuously. The jejunal mucosal expression of endothelin-1 and its receptor subtypes A and B were determined using polymerase chain reaction. RESULTS During cardiopulmonary bypass, superior mesenteric artery flow was preserved but marked jejunal microvascular impairment occurred compared with baseline (mucosal capillary density, 192.2 ± 5.4 vs 150.8 ± 5.1 cm/cm(2); P = .005; tissue blood flow, 501.7 ± 39.3 vs 332.3 ± 27.9 AU; P = .025). The expression of endothelin-1 after cardiopulmonary bypass (3.2 ± 0.4 vs 12.2 ± 0.8 RQ, P = .006) and endothelin subtype A (0.7 ± 0.2 vs 2.4 ± 0.6 RQ; P = .01) was significantly increased compared to the sham group. Vasopressin administration during cardiopulmonary bypass led to normal capillary density (189.9 ± 3.9 vs 178.0 ± 6.3; P = .1) and tissue blood flow (501.7 ± 39.3 vs 494.7 ± 44.4 AU; P = .4) compared with baseline. The expression of endothelin-1 (3.2 ± 0.4 vs 1.8 ± 0.3 RQ; P = .3) and endothelin subtype A (0.7 ± 0.2 vs 0.9 ± 0.2 RQ; P = .5) was not different from the sham group. CONCLUSIONS Cardiopulmonary bypass leads to microvascular impairment of jejunal microcirculation, which is associated with the upregulation of endothelin-1 and endothelin subtype A. The administration of vasopressin minimizes these cardiopulmonary bypass-associated alterations.

Diabetes: a risk factor for catheter-associated infections.

Background and Objectives The incidence of infectious complications associated with continuous regional anesthesia techniques is a matter of concern. Our objective was to determine whether patients suffering from diabetes are at an increased risk of catheter-related infectious complications. Methods The German Network for Regional Anaesthesia database was analyzed between 2007 and 2012. After proof of plausibility, data of 36,881 patients undergoing continuous regional anesthesia were grouped in I: no diabetes (n = 32,891) and II: any diabetes (n = 3990). The analysis focused on catheter-related infections after strict definition. Differences among the groups were tested with t and &khgr;2 tests. Odds ratios were calculated with logistic regression and adjusted for potential confounders. Results Patients with a diagnosis of diabetes had an increased incidence of catheter-related infections (no diabetes 3.0% vs any diabetes 4.2%; P < 0.001). Among all patients, diabetes remained an independent risk factor for infections for all sites after the adjustment for potential confounders (odds ratio [OR] = 1.26; 95% confidence interval [95% CI], 1.02–1.55; P = 0.036). The risk of infection was significantly increased in peripheral catheters only in the lower limb (adjusted OR = 2.42; 95% CI, 1.05–5.57; P = 0.039). If neuraxial catheters were used, the risk was significantly increased only in lumbar epidural (adjusted OR = 2.09; 95% CI, 1.18–3.73; P = 0.012) for diabetic patients compared with nondiabetic patients. Conclusions The presence of diabetes is associated with an increased risk for catheter-related infections in lower limb and lumbar epidural. Specific care should be taken to avoid and detect infections in this population.

Obesity in regional anesthesia – a risk factor for peripheral catheter-related infections

Obesity is believed to increase the risk of surgical site infections and possibly increase the risk of catheter‐related infections in regional anesthesia. We, therefore, analyzed the influence of obesity on catheter‐related infections defined within a national registry for regional anesthesia.

Elevated endothelin-1 level is a risk factor for nonocclusive mesenteric ischemia

OBJECTIVE Nonocclusive mesenteric ischemia may occur after cardiac surgery, commonly in conjunction with the use of cardiopulmonary bypass. Some evidence suggests that endothelin-1 serum levels are increased in patients with mesenteric ischemia, but the association of endothelin-1 and nonocclusive mesenteric ischemia has not been studied. The objective was to investigate whether elevated levels of endothelin-1 could be found in patients exhibiting nonocclusive mesenteric ischemia. METHODS In an observational cohort study, nonocclusive mesenteric ischemia developed in 78 of 865 patients undergoing elective cardiac surgery. Control patients were identified from the cohort through 1:1 propensity score matching. Preoperative and postoperative endothelin-1 serum levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios (with 95% confidence interval) were calculated by logistic regression analyses to determine the risk of endothelin-1 for the development of nonocclusive mesenteric ischemia. RESULTS Patients with nonocclusive mesenteric ischemia had higher preoperative (11.3 vs 9.3 pg/mL; P = .001) and postoperative (15.7 vs 11.1 pg/mL, P < .001) levels of endothelin-1 than the controls. The probability of developing nonocclusive mesenteric ischemia increased with each picogram/milliliter endothelin-1 level preoperatively (odds ratio, 1.29; 95% confidence interval, 1.12-1.49) and each picogram/milliliter postoperatively (odds ratio, 2.04; 95% confidence interval, 1.54-2.72). Receiver operating characteristic analyses showed that elevated endothelin-1 serum levels had a high accuracy to predict nonocclusive mesenteric ischemia (optimal cutoff value of 14.5 pg/mL, area under the curve of 0.77, sensitivity 51%, and specificity 94%). CONCLUSIONS Endothelin-1 seems to predispose patients undergoing cardiac surgery to develop nonocclusive mesenteric ischemia. In addition, it may be a useful marker to identify patients at risk for nonocclusive mesenteric ischemia after cardiac surgery.

Elevated procalcitonin in patients after cardiac surgery: a hint to nonocclusive mesenteric ischemia.

BACKGROUND Nonocclusive mesenteric ischemia (NOMI) can occur after cardiac surgery, commonly in conjunction with use of cardiopulmonary bypass. Some evidence suggests that serum procalcitonin (PCT) levels are increased in patients with mesenteric ischemia; however, an association between PCT and NOMI has not yet been studied. The current study investigates whether elevated serum PCT levels are found in patients exhibiting NOMI. METHODS In an observational cohort study of 865 patients undergoing elective cardiac surgery, 78 experienced NOMI. Preoperative and postoperative PCT levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios and 95% confidence intervals were calculated by logistic regression analyses to predict accuracy of PCT in identifying patients with NOMI. Additional models were calculated, adjusting for potential confounders. RESULTS Patients with NOMI had higher postoperative PCT levels than control patients (20.8 ± 3.2 ng/mL versus 2.3 ± 1.1 ng/mL; p < 0.001). Likelihood of experiencing NOMI increased with each nanogram per milliliter rise in postoperative PCT level (odds ratio, 2.61; 95% confidence interval, 2.05 to 3.32). Receiver operating characteristic analyses showed elevated serum PCT levels to accurately predict occurrence of NOMI (optimal cutoff value, 6.6 ng/mL; area under the curve, 0.94; sensitivity, 71%; specificity, 94%). CONCLUSIONS Postoperative measurement of PCT seems useful to improve the clinical and noninvasive identification of patients with NOMI after cardiac surgery.

Single-dose Antibiotic Prophylaxis in Regional Anesthesia: A Retrospective Registry Analysis.

Background:Catheter-related infection is a serious complication of continuous regional anesthesia. The authors tested the hypothesis that single-dose antibiotic prophylaxis is associated with a lower incidence of catheter-related infections. Methods:Our analysis was based on cases in the 25-center German Network for Regional Anesthesia database recorded between 2007 and 2014. Forty thousand three hundred sixty-two surgical patients who had continuous regional anesthesia were grouped into no antibiotic prophylaxis (n = 15,965) and single-dose antibiotic prophylaxis (n = 24,397). Catheter-related infections in each group were compared with chi-square test after 1:1 propensity-score matching. Odds ratios (ORs [95% CI]) were calculated with logistic regression and adjusted for imbalanced variables (standardized difference more than 0.1). Results:Propensity matching successfully paired 11,307 patients with single-dose antibiotic prophylaxis (46% of 24,397 patients) and with 11,307 controls (71% of 15,965 patients). For peripheral catheters, the incidence without antibiotics (2.4%) was greater than with antibiotic prophylaxis (1.1%, P < 0.001; adjusted OR, 2.02; 95% CI, 1.49 to 2.75, P < 0.001). Infections of epidural catheters were also more common without antibiotics (5.2%) than with antibiotics (3.1%, P < 0.001; adjusted OR, 1.94; 95% CI, 1.55 to 2.43, P < 0.001). Conclusions:Single-dose antibiotic prophylaxis was associated with fewer peripheral and epidural catheter infections.