Hans-Joachim Priebe

Guidelines for pre-operative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery

The American College of Cardiology, American Heart Association, and the European Society of Cardiology are all in the process of completing updated versions of our Guidelines for Perioperative Care. Our respective writing committees are undertaking a careful analysis of all relevant validated studies and always incorporate appropriate new trials and meta-analyses into our evidence review. In the interim, our current joint position is that the initiation of beta blockers in patients who will undergo non-cardiac surgery should not be considered routine, but should be considered carefully by each patients treating physician on a case-by-case basis. Please see the expression of concern which is free to view in Eur Heart J (2013) 34 (44): 3460; doi: 10.1093/eurheartj/eht431. AAA : abdominal aortic aneurysm ACC : American College of Cardiology ACE : angiotensin-converting enzyme ACS : acute coronary syndrome AHA : American Heart Association AR : aortic regurgitation ARB : angiotensin receptor blocker AS : aortic stenosis AF : atrial fibrillation BBSA : β-blocker in spinal anaesthesia BNP : brain natriuretic peptide CABG : coronary artery bypass grafting CARP : coronary artery revascularization prophylaxis CASS : coronary artery surgery study CI : confidence interval COX-2 : cyclooxygenase-2 COPD : chronic obstructive pulmonary disease CPET : cardiopulmonary exercise testing CPG : Committee for Practice Guidelines CRP : C-reactive protein CT : computed tomography cTnI : cardiac troponin I cTnT : cardiac troponin T CVD : cardiovascular disease DECREASE : Dutch Echocardiographic Cardiac Risk Evaluating Applying Stress Echo DES : drug-eluting stent DIPOM : Diabetes Postoperative Mortality and Morbidity DSE : dobutamine stress echocardiography ECG : electrocardiography ESC : European Society of Cardiology FEV1 : forced expiratory volume in 1 s FRISC : fast revascularization in instability in coronary disease HR : hazard ratio ICU : intensive care unit IHD : ischaemic heart disease INR : international normalized ratio LMWH : low molecular weight heparin LQTS : long QT syndrome LR : likelihood ratio LV : left ventricular MaVS : metoprolol after surgery MET : metabolic equivalent MI : myocardial infarction MR : mitral regurgitation MRI : magnetic resonance imaging MS : mitral stenosis NICE-SUGAR : normoglycaemia in intensive care evaluation and survival using glucose algorithm regulation NSTEMI : non-ST-segment elevation myocardial infarction NT-proBNP : N-terminal pro-brain natriuretic peptide NYHA : New York Heart Association OPUS : orbofiban in patients with unstable coronary syndromes OR : odds ratio PaCO2 : mixed expired volume of alveolar and dead space gas PAH : pulmonary arterial hypertension PETCO2 : end-tidal expiratory CO2 pressure PCI : percutaneous coronary intervention PDA : personal digital assistant POISE : PeriOperative ISchaemic Evaluation trial QUO-VADIS : QUinapril On Vascular ACE and Determinants of ISchemia ROC : receiver operating characteristic SD : standard deviation SMVT : sustained monomorphic ventricular tachycardia SPECT : single photon emission computed tomography SPVT : sustained polymorphic ventricular tachycardia STEMI : ST-segment elevation myocardial infarction SVT : supraventricular tachycardia SYNTAX : synergy between percutaneous coronary intervention with taxus and cardiac surgery TACTICS : treat angina with aggrastat and determine cost of therapy with an invasive or conservative strategy TIA : transient ischaemic attack TIMI : thrombolysis in myocardial infarction TOE : transoesophageal echocardiography UFH : unfractionated heparin VCO2 : carbon dioxide production VE : minute ventilation VHD : valvular heart disease VKA : vitamin K antagonist VO2 : oxygen consumption VPB : ventricular premature beat VT : ventricular tachycardia Guidelines and Expert Consensus Documents aim to present management and recommendations based on the relevant evidence on a particular subject in order to help physicians to select the best possible management strategies for the individual patient suffering from a specific condition, taking into account not only the impact on outcome, but also the risk–benefit ratio of particular diagnostic or therapeutic means. Guidelines are no substitutes for textbooks. The legal implications of medical guidelines have been discussed previously.1 A great number of Guidelines and Expert Consensus Documents have been issued in recent years by the European Society of Cardiology (ESC) and also by other organizations or related societies. Because of the impact on clinical practice, quality criteria for development of guidelines have been established in order to make all decisions transparent to the user. The recommendations for formulating and issuing ESC guidelines and Expert Consensus Documents can be found on the ESC website in the guidelines section (www.escardio.org). In brief, experts in the field are selected and undertake a comprehensive review of the published evidence for management and/or prevention of a given condition. …

Recovery after anesthesia with remifentanil combined with propofol, desflurane, or sevoflurane for otorhinolaryngeal surgery

Because no previous investigation has directly compared the combination of remifentanil (REM) and a hypnotic with that of REM and the newer volatile anesthetics, we studied recovery characteristics and patient satisfaction after the combination of REM with propofol (PRO), desflurane (DES), or sevoflurane (SEVO). One hundred twenty patients were randomly assigned to receive anesthesia with either REM/PRO, REM/DES, REM/SEVO, or thiopental/alfentanil/isoflurane/N2O (control group) for ear, nose, and throat surgery (n = 30 each). In the REM groups, the dosage of PRO (75 &mgr;g · kg−1 · min−1), and of DES or SEVO (0.5 minimum alveolar anesthetic concentration) was kept unchanged, and REM was titrated to hemodynamic response. The control group was managed according to standard practice. Early recovery (times to eye opening, extubation, and statement of name and date of birth) was predictably faster and more complete in the REM groups compared with the control group. However, late recovery (times to discharge from postanesthesia care unit and hospital) and overall patient satisfaction were not different among groups. No clinically relevant differences existed among the three REM groups. In conclusion, the combination of REM infusion with small-dose DES, SEVO, or PRO is characterized by predictably rapid, early recovery. However, late recovery and patient satisfaction are comparable to a conventional anesthetic technique. Implications Remifentanil anesthesia, combined with small-dose propofol, desflurane, or sevoflurane, enables predictably fast and smooth early recovery after ear, nose, and throat surgery. Despite such faster, early recovery and less need for postoperative analgesic and antiemetic medication, late recovery was comparable among the remifentanil combination groups and the control group.

Intravascular volume replacement therapy with synthetic colloids: is there an influence on renal function?

A bsolute or relative blood volume deficits often occur in patients undergoing surgery and in the intensive care unit (ICU). The preoperative medical status of the patient, medication, anesthesia, surgical trauma, and inflammatory reactions may all alter intravascular volume status. Appropriate intravascular volume replacement is a fundamental component of critical care management because failure to treat hypovolemia may lead to multiple organ dysfunction syndrome or death (1). There is controversy as to whether crystalloids or colloids are preferred for intravascular volume replacement (2–5). However, because colloids with different physicochemical characteristics are now available in several countries, a colloid versus colloid debate has been added to the already existing crystalloid versus colloid fluid replacement controversy. When synthetic colloids (e.g., dextran [DEX], gelatin, or different hydroxyethyl starch [HES] solutions) are used, side effects may occur (6). Development of renal insufficiency after the administration of synthetic colloids has been quoted as reason for avoiding them (7–12). More than a decade ago, a review on various fluid replacement therapies in septic shock concluded that only DEX appears to be associated with the development of renal dysfunction (13). A more recently published review asked whether HES is “safe or not” (14). In this review, several adverse effects of HES were discussed, mainly those on coagulation. Adverse effects on renal function were not mentioned. Finally, the most recent review on fluid resuscitation in trauma patients discussed the pros and cons of currently available solutions (15). No cause-effect relationship was postulated between the use of any of the colloid solutions and the development of renal dysfunction. Against this background, it is surprising to find statements such as “renal toxicity of HES is now well recognized” (16) or that the administration of even small doses of HES causes tubular lesions in patients predisposed to renal insufficiency (17). Obviously, our current understanding in this area is limited. Accordingly, this overview will briefly outline the mechanisms and causes of acute renal failure (ARF) and review whether the use of colloid solutions could alter renal function.

The modifying effects of stimulation pattern and propofol plasma concentration on motor-evoked potentials

The quality of intraoperative motor-evoked potentials (MEPs) largely depends on the stimulation pattern and anesthetic technique. Further improvement in intraoperative MEP recording requires exact knowledge of the modifying effects of each of these factors. Accordingly, we designed this study to characterize the modifying effect of different stimulation patterns during different propofol target plasma concentrations (PTPCs) on intraoperatively recorded transcranial electrical MEPs. In 12 patients undergoing craniotomy, stimulation patterns (300–500 V; 100–1000 Hz; 1–5 stimuli) were varied randomly at different PTPCs (2, 4, and 6 &mgr;g/mL). Remifentanil was administered unchanged at 0.2 &mgr;g · kg−1 · min−1. MEPs were recorded from the thenar and hypothenar muscles. Analysis of MEPs was blinded to the PTPC. Three-way analysis of variance revealed significant main effects of increasing stimulation intensity, frequency, and number of stimuli on MEP amplitude (P < 0.05). Maximum MEP amplitudes and recording success rates were observed with three or more stimuli delivered at 1000 Hz and ≥150 V. A significant main effect of PTPC (2 vs 4 and 6 &mgr;g/mL) on MEP amplitude was observed at the thenar recording site only (P < 0.05). An amplitude ratio calculated from corresponding MEPs evoked by double and quadruple stimulation proved to be insensitive to changes in PTPC. In conclusion, MEP characteristics varied significantly in response to changes in stimulation pattern and less to changes in PTPC.

Accuracy of automatic tube compensation in new-generation mechanical ventilators.

ObjectiveTo compare performance of flow-adapted compensation of endotracheal tube resistance (automatic tube compensation, ATC) between the original ATC system and ATC systems incorporated in commercially available ventilators. DesignBench study. SettingUniversity research laboratory. SubjectsThe original ATC system, Dräger Evita 2 prototype, Dräger Evita 4, Puritan-Bennett 840. InterventionsThe four ventilators under investigation were alternatively connected via different sized endotracheal tubes and an artificial trachea to an active lung model. Test conditions consisted of two ventilatory modes (ATC vs. continuous positive airway pressure), three different sized endotracheal tubes (inner diameter 7.0, 8.0, and 9.0 mm), two ventilatory rates (15/min and 30/min), and four levels of positive end-expiratory pressure (0, 5, 10, and 15 cm H2O). Measurements and Main ResultsPerformance of tube compensation was assessed by the amount of tube-related (additional) work of breathing (WOBadd), which was calculated on the basis of pressure gradient across the endotracheal tube. Compared with continuous positive airway pressure, ATC reduced inspiratory WOBadd by 58%, 68%, 50%, and 97% when using the Evita 4, the Evita 2 prototype, the Puritan-Bennett 840, and the original ATC system, respectively. Depending on endotracheal tube diameter and ventilatory pattern, inspiratory WOBadd was 0.12–5.2 J/L with the original ATC system, 1.5–28.9 J/L with the Puritan-Bennett 840, 10.4–21.0 J/L with the Evita 2 prototype, and 10.1–36.1 J/L with the Evita 4 (difference between each ventilator at identical test situations, p < .025). Expiratory WOBadd was reduced by 5%, 26%, 1%, and 70% with the Evita 4, the Evita 2 prototype, the Puritan-Bennett 840, and the original ATC system, respectively. The expiratory WOBadd caused by an endotracheal tube of 7.0 mm inner diameter was 5.5–42.2 J/L at a low ventilatory rate and 19.6–82.3 J/L at a high ventilatory rate. It was lowest with the original ATC system and highest with the Evita 4 ventilator (p < .025). ConclusionsFlow-adapted tube compensation by the original ATC system significantly reduced tube-related inspiratory and expiratory work of breathing. The commercially available ATC modes investigated here may be adequate for inspiratory but probably not for expiratory tube compensation.

The Effects of Stimulation Pattern and Sevoflurane Concentration on Intraoperative Motor-Evoked Potentials

The usefulness of intraoperative monitoring of motor-evoked potentials (MEPs) during inhaled anesthesia is limited by the suppressive effects of volatile anesthetics on MEP signals. We investigated the effects of different stimulation patterns and end-tidal concentrations of sevoflurane on intraoperative transcranial electrical MEPs. In 12 patients undergoing craniotomy, stimulation patterns (300–500 V, 100–1000 Hz, 1–5 stimuli) and multiples (0.5, 0.75, and 1.0) of minimum alveolar concentration (MAC) of sevoflurane were varied randomly while remifentanil was administered at a constant rate of 0.2 &mgr;g · kg−1 · min−1. MEPs were recorded from thenar and hypothenar muscles and analyzed without knowledge of the respective MAC. Three-way analysis of variance revealed significant main effects for increasing stimulation intensity, frequency, and number of stimuli on MEP amplitude (P < 0.05). Maximum MEP amplitudes and recording success rates were observed during 4 stimuli delivered at 1000 Hz and 300 V. A significant main effect of sevoflurane concentration (0.5 versus 0.75 and 1 MAC multiple) on MEP amplitude was observed at the thenar recording site only (P < 0.05). In conclusion, MEP characteristics varied significantly with changes in stimulation pattern and less so with changes in sevoflurane concentration. The results suggest that high frequency repetitive stimulation allows intraoperative use of MEP monitoring during up to 1 MAC multiple of sevoflurane and constant infusion of remifentanil up to 0.2 &mgr;g · kg−1 · min−1.

Electrical impedance tomography to confirm correct placement of double-lumen tube: a feasibility study

BACKGROUND Double-lumen tubes (DLTs) are frequently used to establish one-lung ventilation (OLV). Their correct placement is crucial. We hypothesized that electrical impedance tomography (EIT) reliably displays distribution of ventilation between left and right lung and may thus be used to verify correct DLT placement online. METHODS Regional ventilation was studied by EIT in 40 patients requiring insertion of left-sided DLTs for OLV during thoracic surgery. EIT was recorded during two-lung ventilation before induction of anaesthesia and after DLT placement, and during OLV in the supine and subsequently in the lateral position. EIT measurements were made before and after verification of correct DLT placement by fibreoptic bronchoscopy (FOB). RESULTS EIT accurately displayed distribution of ventilation between left and right lung online. All cases (n=5) of initially misplaced DLTs in the contralateral right main bronchus were detected by EIT. However, EIT did not allow prediction of FOB-detected endobronchial cuff misplacement requiring DLT repositioning. Furthermore, after DLT repositioning, distribution of ventilation, as assessed by EIT, did not change significantly (all P>0.5). CONCLUSIONS This study demonstrates that EIT enables accurate display of left and right lung ventilation and, thus, non-invasive online recognition of misplacement of left-sided DLTs in the contralateral main bronchus. However, as distribution of ventilation did not correlate with endobronchial cuff placement, EIT cannot replace FOB in the routine control of DLT position.

Protective effects of inhaled carbon monoxide in pig lungs during cardiopulmonary bypass are mediated via an induction of the heat shock response

BACKGROUND Cardiopulmonary bypass (CPB) may cause acute lung injury leading to increased morbidity and mortality after cardiac surgery. Preconditioning by inhaled carbon monoxide reduces pulmonary inflammation during CPB. We hypothesized that inhaled carbon monoxide mediates its anti-inflammatory and cytoprotective effects during CPB via induction of pulmonary heat shock proteins (Hsps). METHODS Pigs were randomized either to a control group, to standard CPB, to carbon monoxide+CPB, or to quercetin (a flavonoid and unspecific inhibitor of the heat shock response)+control, to quercetin+CPB, and to quercetin+carbon monoxide+CPB. In the carbon monoxide groups, lungs were ventilated with 250 ppm carbon monoxide in addition to standard ventilation before CPB. At various time points, lung biopsies were obtained and pulmonary Hsp and cytokine concentrations determined. RESULTS Haemodynamic parameters were largely unaffected by CPB, carbon monoxide inhalation, or administration of quercetin. Compared with standard CPB, carbon monoxide inhalation significantly increased the pulmonary expression of the Hsps 70 [27 (SD 3) vs 69 (10) ng ml(-1) at 120 min post-CPB, P<0.05] and 90 [0.3 (0.03) vs 0.52 (0.05) after 120 min CPB, P<0.05], induced the DNA binding of heat shock factor-1, reduced interleukin-6 protein expression [936 (75) vs 320 (138) at 120 min post-CPB, P<0.001], and decreased CPB-associated lung injury (assessed by lung biopsy). These carbon monoxide-mediated effects were inhibited by quercetin. CONCLUSIONS As quercetin, a Hsp inhibitor, reversed carbon monoxide-mediated pulmonary effects, we conclude that the anti-inflammatory and protective effects of preconditioning by inhaled carbon monoxide during CPB in pigs are mediated by an activation of the heat shock response.

The Effects of Increasing Concentrations of Desflurane on Systemic Oxygenation During One-lung Ventilation in Pigs

UNLABELLED During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction reduces venous admixture and attenuates the decrease in arterial O2 tension by diverting blood from the nonventilated to the ventilated lung. In vitro, increasing concentrations of desflurane depresses hypoxic pulmonary vasoconstriction in a dose-dependent manner. Accordingly, we investigated the effects of increasing concentrations of desflurane on oxygenation during OLV in vivo. Thirteen pigs (25-30 kg) were anesthetized (induction: propofol 2-3 mg/kg IV; maintenance: N2O/O2 50%/50%, desflurane 3%, propofol 50 microg x kg(-1) min(-1), and vecuronium 0.2 mg x kg(-1) x h(-1) IV), orotracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a leftsided, 28F, double-lumen tube was placed via tracheotomy. After double-lumen tube placement, N2O and desflurane were discontinued, propofol was increased to 200 microg x kg(-1) x min(-1), and the fraction of inspired oxygen was adjusted at 0.8. Anesthesia was then continued in random order with desflurane 5%, 10%, or 15% end-tidal concentrations while propofol was discontinued. Whereas mixed venous PO2, mean arterial pressure, cardiac output, and shunt fraction decreased in a dose-dependent manner, PaO2 remained unchanged with increasing concentrations of desflurane during OLV. These findings indicate that, in vivo, increasing concentrations of desflurane do not necessarily worsen oxygenation during OLV. IMPLICATIONS Oxygenation during one-lung ventilation depends on reflex vasoconstriction in the nonventilated lung. In vitro, desflurane inhibits this reflex dose-dependently. Our results indicate that, in vivo, this does not necessarily translate to dose-dependent decreases in oxygenation during one-lung ventilation.

Inhaled Carbon Monoxide Prevents Acute Kidney Injury in Pigs After Cardiopulmonary Bypass by Inducing a Heat Shock Response

BACKGROUND: Cardiopulmonary bypass (CPB) may be associated with acute kidney injury (AKI). Inhaled carbon monoxide (CO) is cyto- and organ-protective. We hypothesized that pretreatment with inhaled CO prevents CPB-associated AKI. METHODS: Pigs (n = 38) were nonrandomly assigned to SHAM, standard CPB, pretreatment with inhaled CO (250 ppm, 1 hour) before SHAM or CPB, to pretreatment with quercetin (an inhibitor of the heat shock response), and to pretreatment with SnPPIX (an inhibitor of endogenously derived CO), before CO inhalation and CPB. The primary outcome variables were markers of AKI (urea, uric acid, creatinine, cystatin C, neutrophil gelatinase-associated lipocalin, interleukin-6, tumor necrosis factor-&agr;), which were determined 120 minutes after CPB. Secondary outcome variables were heat shock protein (HSP)-70 and heme oxygenase-1 protein expressions as indicators of CO-mediated heat shock response. RESULTS: Pretreatment with inhaled CO attenuated (all P < 0.001) CPB-associated, (1) increases in serum concentrations of cystatin C (64 ± 14 vs 28 ± 9 ng/mL), neutrophil gelatinase-associated lipocalin (391 ± 65 vs 183 ± 56 ng/mL), renal tumor necrosis factor-&agr; (450 ± 73 vs 179 ± 110 pg/mL), and interleukin-6 (483 ± 102 vs 125 ± 67 pg/mL); (2) increase in renal caspase-3 activity (550 ± 66 vs 259 ± 52 relative fluorescent units); and (3) histological evidence of AKI. These effects were accompanied by activation of HSP-70 (196 ± 64 vs 554 ± 149 ng/mL, P < 0.001). Pretreatment with the heat shock response inhibitor quercetin counteracted the CO-associated biochemical and histological renoprotective effects (all P < 0.001), whereas the heme oxygenase inhibitor SnPPIX only partially counteracted the CO-associated renoprotection and the activation of the heat shock response. CONCLUSIONS: CO treatment before CPB was associated with evidence of renoprotection, demonstrated by fewer histological injuries and decreased cystatin C concentrations. The findings that the antiinflammatory and antiapoptotic effects of CO were accompanied by activation of HSP-70, which in turn were reversed by quercetin, suggest that renoprotection by pretreatment with inhaled CO before CPB is mediated by activation of the renal heat shock response.