[Update in Obstetric Anesthesia - Tried and Trusted Methods, Controversies and New Perspectives]. / Geburtshilfliche Anästhesie: Altbewährtes, Kontroversen und neue Perspektiven ­ Teil 2.

Since 1975, a plethora of lectures within the context of annual meetings relevant for the clinical care has been summarized in "what's new in obstetric anesthesia" by the society for Obstetric anesthesia and Perinatology which can be recommended to everyone interested in anaesthesiology in the delivery room. After the death of Gerard W. Ostheimer, Professor of Anaesthesiology at Brigham and Women's Hospital in Boston, Massachusetts, it became renamed the Gerard W. Ostheimer "what's new in obstetric anesthesia" lecture to honor his contributions to regional anesthesia and obstetric anaesthesia. Each year the event held by selected professional representatives and their imprint in leading anesthesia journals give insight into a critical appraisal of recent literature and the possible consequences for - but not only - the anaesthetic delivery room practice.A similar event has been established in Germany for more than 16 years (first event on April 1, 2000, most recently held on February 27, 2016, in Munich): the obstetrical anesthesia symposium of the academic working group "regional anesthesia and obstetrical anesthesia" [1], [2]."Evergreens" or "hot topics" with regard to anaesthesiological delivery room practice are presented and discussed regularly. The lectures often reveal the subtle change of the issues being debated much earlier than traditional textbook chapters do. This manuscript summarizes important findings from the last symposium held in 2016. Part I focuses on relevant causes for maternal morbidity and mortality as well as preventive measures, pregnancy in obese patients and sepsis in obstetric anaesthesia. Part II addresses established standards and new perspectives in the direct obstetric setting regarding epidural analgesia, post-dural puncture headache, anaesthesia and analgesia during and after caesarean section, haemodynamic monitoring during cesarean section and postpartum haemorrhage.

[Update in Obstetric Anesthesia: Tried and Trusted Methods, Controversies and New Perspectives - Part 1]. / Geburtshilfliche Anästhesie: Altbewährtes, Kontroversen und neue Perspektiven ­ Teil 1.

Since 1975, a plethora of lectures within the context of annual meetings relevant for the clinical care has been summarized in "what's new in obstetric anesthesia" by the Society for Obstetric Anesthesia and Perinatology which can be recommended to everyone interested in anaesthesiology in the delivery room. After the death of Gerard W. Ostheimer, Professor of Anaesthesiology at Brigham and Women's Hospital in Boston, Massachusetts, it became renamed the Gerard W. Ostheimer "what's new in obstetric anesthesia" lecture to honor his contributions to regional anesthesia and obstetric anaesthesia. Each year the event held by selected professional representatives and their imprint in leading anesthesia journals give insight into a critical appraisal of recent literature and the possible consequences for - but not only - the anaesthetic delivery room practice.A similar event has been established in Germany for more than 16 years: the obstetrical anesthesia symposium of the academic working group "regional anesthesia and obstetrical anesthesia" 1, 2."Evergreens" or "hot topics" with regard to anaesthesiological delivery room practice are presented and discussed regularly. The lectures often reveal the subtle change of the issues being debated much earlier than traditional textbook chapters do. This manuscript summarizes important findings from the last symposium held in 2016. Part I focuses on relevant causes for maternal morbidity and mortality as well as preventive measures, pregnancy in obese patients and sepsis in obstetric anaesthesia. Part II addresses established standards and new perspectives in the direct obstetric setting regarding epidural analgesia, post-dural puncture headache, anaesthesia and analgesia during and after caesarean section, haemodynamic monitoring during cesarean section and postpartum haemorrhage.

Sleep at baseline and after electroconvulsive therapy in patients with major depression.

Sleep in major depressive disorder is frequently altered and possibly indicative for treatment outcomes. For example, increased rapid eye movement (REM-) sleep density seems to predict worse treatment outcomes of psychotherapy. We therefore investigated pre-treatment sleep and sleep changes after termination of electroconvulsive therapy (ECT). Sleep was polysomnographically recorded. The analysed sample consisted of 15 inpatients with ages ranging from 30 to 80 (mean 59 years). ECT was applied two times a week up to 7 weeks. Stable remission of depressive symptoms was defined by a score in the Hamilton Rating Scale of Depression <8 at six months after ECT. The main results were an increase in sleep efficiency and a decrease in the number of awakenings within the course of ECT in the entire patient group. Significant increases in slow wave sleep and REM sleep duration and a significant decrease in REM density were only seen in stable remitters and not in non-remitters. In pre-treatment baseline sleep a higher REM density of the first REM sleep period was significantly associated with better ECT outcome. In conclusion, REM density of the first REM sleep period seems to be an interesting candidate as putative predictor of stable treatment outcome of ECT.

Comparison of a continuous noninvasive arterial pressure device with invasive measurements in cardiovascular postsurgical intensive care patients: a prospective observational study.

BACKGROUND: Arterial pressure monitoring using the a continuous noninvasive arterial pressure (CNAP) device during general anaesthesia is known to be interchangeable with continuous invasive arterial pressure (CIAP) monitoring. Agreement with invasive measurements in cardiovascular postsurgical intensive care patients has not been assessed. OBJECTIVE: The objective of this study is to assess the agreement and interchangeability of CNAP with CIAP in cardiovascular postsurgical patients and to determine the effects of cardiac arrhythmia, catecholamine dosage, respiratory weaning and calibration intervals on agreement. DESIGN: A prospective observational study. SETTING: German university hospital cardiovascular ICU. Data were collected from April 2010 to December 2011. PATIENTS: From 110 enrolled patients, 104 were included. Inclusion criteria were American Society of Anaesthesiologists (ASA) physical status III or IV patients undergoing controlled ventilation. Exclusion criteria included emergencies, complete heart block and marked arterial pressure differences greater than 10 mmHg in the two arms. MAIN OUTCOME MEASURES: Bland-Altman plots, bias, precision, 95% limits of agreement, percentage error and agreement : tolerability indexes (ATIs) were estimated to determine clinical agreement. RESULTS: From 11 222 arterial pressure readings, biases (SD) for CIAP-CNAP for systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) for all patients were 4.3 (11.6), -9.4 (8) and -6 (7.6) mmHg, respectively. Cardiac arrhythmia (4.1 (13.1), -14.4 (8.3), -9.5 (8.9) mmHg) and long interval to last calibration [4.5 (15), -9.8 (9.5), -6.4 (9.1) mmHg] impaired the accuracy of CNAP with failed interchangeability criteria defined by the percentage error. In contrast, use of catecholamines (epinephrine or norepinephrine infusions >0.1 µg kg min), short calibration intervals and weaning conditions did not affect accuracy, interchangeability and agreement, especially of MAP. Agreement was defined as acceptable for MAP for all data and subgroups (ATI 0.8 to 1.0) and at worst, marginal for SAP and DAP (ATI 0.9 to 1.6). CONCLUSION: CNAP showed acceptable agreement defined by the ATI with invasive measurements for MAP and partially for DAP, but there was considerable variability for SAP. MAP should be preferred for clinical decision making. Cardiac arrhythmia, in contrast to catecholamine dosage or weaning procedures, impaired the accuracy, agreement and interchangeability of CNAP. TRIAL REGISTRATION: Clinical trials.gov identifier NCT01003665.

Correlation of surgical pleth index with stress hormones during propofol-remifentanil anaesthesia.

Eighty patients undergoing elective ear-nose-throat surgery were enrolled in the present study to investigate the relationship between surgical pleth index (SPI) and stress hormones (ACTH, cortisol, epinephrine, norepinephrine) during general anaesthesia which was induced and maintained with propofol and remifentanil using a target-controlled infusion. The study concluded that the SPI had moderate correlation to the stress hormones during general anaesthesia, but no correlation during consciousness. Furthermore, SPI values were able to predict ACTH values with high sensitivity and specificity.

Effects of cerebral hypoperfusion on bispectral index: a randomised, controlled animal experiment during haemorrhagic shock.

BACKGROUND: The aim of this porcine haemorrhagic shock model was to investigate the changes of bispectral index (BIS) after slow and fast recovery of cerebral perfusion, and its correlation with plasma propofol concentrations. METHODS: After Animal Investigational Committee approval, 16 pigs during propofol anaesthesia underwent a liver trauma with severe hypotension, and were randomly assigned to receive therapy for either slow recovery (fluid resuscitation; slow group; n=8) or fast recovery of cerebral perfusion (vasopressor combined with hypertonic-saline-starch; fast group; n=8), respectively. Cerebral perfusion pressure (CPP=MAP-ICP), cerebral tissue oxygenation index (TOI), BIS, and plasma concentrations of propofol and haemoglobin were measured at baseline (Pre-shock), haemodynamic decompensation (Shock), and 5 (Therapy) and 30 min (End) after therapy, respectively. RESULTS: CPP, TOI, and BIS decreased significantly during shock (pre-shock vs. shock, fast: CPP: 65+/-14 vs. 15+/-4 mmHg; TOI: 64+/-6 vs. 47+/-7%; BIS 60+/-5 vs. 9+/-10; slow: CPP: 60+/-12 vs. 13+/-7 mmHg; TOI: 68+/-7 vs. 49+/-7%; BIS 63+/-5 vs. 13+/-12; P<0.05). In the fast group, CPP, TOI, and BIS increased after therapy compared to the slow group (Therapy, fast: CPP: 47+/-15 mmHg, TOI: 61+/-7%, BIS: 47+/-21; slow: CPP: 18+/-9 mmHg, TOI: 51+/-5%, BIS: 21+/-19; P<0.05). Propofol and haemoglobin concentrations were comparable between groups throughout the resuscitation phase. CONCLUSIONS: In a haemorrhagic shock scenario, therapies with different impact on cerebral perfusion resulted in differing changes of BIS values, while plasma propofol and haemoglobin concentrations were comparable during the resuscitation phase; this suggests that BIS may also have reflected changes of cerebral perfusion.

[Organprotection in cardiac risk patients--rational of perioperative beta-adrenoceptor-antagonists and statins]. / Perioperative Organprotektion - Beta-Blocker und Statine.

The number of patients with limited organ function is steadily increasing due to the aging of the population. Consequently, a growing number of patients needing surgery is accompanied by serious comorbidities. These patients are at high risk of perioperative organ dysfunction. In this context cardiac events (e.g. cardiac arrhythmias, angina or myocardial infarction) play a major role with significant impact on postoperative care, long term outcome and economic sequelae. Thus, anaesthesiologists must prevent such events in the perioperative period. Besides general measures such as adequate analgesia, protection from stressful events and sufficient volume replacement, medical intervention with beta-blockers or HMG-CoA-reductase-inhibitors (statins) are necessary to reduce the incidence of perioperative cardiac events. Both beta-blockers and HMG-CoA-reductase-inhibitors are known to exhibit pleiotropic effects (defined as additional cardioprotective effects) besides the primary blockade of the beta-adrenergic receptor or the inhibition of the synthesis of serum cholesterol, respectively. Both groups of drugs improve cardiac function, decrease inflammatory response, decrease activation of blood coagulation and stabilize endothelial plaques. Based on the current literature the following recommendations are published concerning the perioperative administration of beta-blockers: (i) Patients who are on beta-blockers on a regular basis following guidelines concerning chronic treatment of cardiovascular diseases should continue this medication throughout the perioperative period; (ii) a sufficient indicator of an adequate therapy is the baseline heart rate. It should not exceed 60-70bpm at rest; (iii) the Revised Cardiac Risk Index (RCRI) is a widely accepted score to estimate the patient's perioperative cardiac risk; (iv) patients with a RCRI > or =3 should not be scheduled for routine surgery without sufficient beta-adrenergic-receptor blockade; (v) in patients at high cardiac risk based on the RCRI who are scheduled for emergency surgery beta-blocker-therapy should not be initiated de novo perioperatively. However, for perioperative treatment of tachycardia or hypertension beta-blockers are the drug of first choice. Concerning perioperative statin-therapy the following recommendations are suggested: (i) chronic statin-therapy should be continued throughout surgery and the perioperative period; (ii) in patients without chronic statin-therapy scheduled for vascular surgery this treatment should be started perioperativly; (iii) no data is available concerning other patient populations; (iv) if statin-therapy is indicated it should be started independently from baseline serum LDL-C-concentration; (v) side effects of statin-therapy are rare and usually not live threatening, thus treatment is considered to be without serious risks to the patient.

Comparison of surgical stress index-guided analgesia with standard clinical practice during routine general anesthesia: a pilot study.

BACKGROUND: Surgical stress index (SSI), a novel multivariate index, has recently been proven to react well to surgical nociceptive stimuli and analgesic drug concentration changes during general anesthesia. We investigated the feasibility of application of SSI for guidance of remifentanil administration during propofol-remifentanil anesthesia. METHODS: Eighty patients scheduled for elective ear-nose-throat surgery were randomized into two groups, SSI-guided analgesia group (SSI group) and standard practice analgesia group (control group). In both groups, anesthesia was maintained with a propofol target-controlled infusion and adjusted stepwise by 0.5 microg/ml to keep bispectral index values between 40 and 60. In the SSI group, the predicted effect-site concentration of remifentanil was adjusted stepwise by 1 ng/ml to keep SSI values between 20 and 50, whereas in the control group, predicted effect-site concentration of remifentanil was adjusted according to traditional inadequate analgesia criteria. Anesthetics consumption, recovery times, and incidence of unwanted events were recorded. RESULTS: Remifentanil consumption (average normalized infusion rate) was lower in the SSI group than in the control group (mean +/- SD, 9.5 +/- 3.8 microg . kg(-1) . h(-1) vs. 12.3 +/- 5.2 microg . kg(-1) . h(-1); P < 0.05). The number of unwanted events was less in the SSI group (84) than in the control group (556; P < 0.01). Recovery times were comparable between groups. No patient reported intraoperative recall. CONCLUSIONS: SSI-guided anesthesia resulted in lower remifentanil consumption, more stable hemodynamics, and a lower incidence of unwanted events.

Paracetamol versus metamizol in the treatment of postoperative pain after breast surgery: a randomized, controlled trial.

BACKGROUND AND OBJECTIVE: Intravenously administered paracetamol is an effective analgesic in postoperative pain management. However, there is a lack of data on the effect of intravenous (i.v.) paracetamol on pain following soft tissue surgery. METHODS: Eighty-seven patients undergoing elective breast surgery with total i.v. anaesthesia (propofol/remifentanil) were randomized to three groups. Group para received 1 g i.v. paracetamol 20 min before and 4, 10 and 16 h after the end of the operation. Group meta and plac received 1 g i.v. metamizol or placebo, respectively, scheduled at the same time points. All patients had access to i.v. morphine on demand to achieve adequate pain relief. RESULTS: No significant difference in total morphine consumption between groups was detectable. The proportion of patients who did not receive any morphine in the postoperative period was significantly higher in group para (42%) than in group plac (4%). Ambulation was significantly (P < 0.05) earlier in group para (4.0 +/- 0.2 h) than in groups meta (4.6 +/- 0.2 h) and plac (5.5 +/- 1.0 h). No differences were observed between groups meta and plac. There were no differences between groups with regard to incidence of postoperative nausea and vomiting or changes in vigilance. CONCLUSION: Neither i.v. paracetamol nor i.v. metamizol provided a significant reduction in total postoperative morphine consumption compared with placebo in the management of postoperative pain after elective breast surgery. Administration of paracetamol resulted in a significant reduction in the number of patients needing opioid analgesics to achieve adequate postoperative pain relief.

Effects of norepinephrine on dynamic variables of fluid responsiveness during hemorrhage and after resuscitation in a pediatric porcine model.

BACKGROUND: The effect of vasopressors on pulse pressure variation (PPV), stroke volume variation (SVV) and on the volumetric variable global end-diastolic volume (GEDV) during changing loading conditions is currently under debate. The aim of our study was to investigate the effect of norepinephrine (NE) on PPV, SVV and GEDV in a pediatric animal model of hemorrhage and resuscitation. METHODS: Eight anesthetized piglets were studied at normovolemia, after stepwise blood withdrawal (25 ml x kg(-1)), after infusion of NE to restore mean arterial pressure (MAP), after NE titration was stopped and shed blood was retransfused and finally again after NE titration. Stroke volume (SV) was measured using a thermodilution pulmonary artery catheter. GEDV was measured by transpulmonary thermodilution. PPV and SVV were monitored continuously by pulse contour analysis. In response to NE administration during hemorrhage, MAP significantly increased (P < 0.01), PPV significantly decreased (P = 0.02), whereas SVV, SV and GEDV remained unchanged. After retransfusion, SVV and GEDV significantly correlated with volume induced percentage change in SV. This significant correlation was reversed after NE administration for SVV and persisted for GEDV. In conclusion, NE administration significantly affected PPV and SVV, whereas the volumetric variable GEDV remained unchanged.

Postoperative neurocognitive dysfunction in elderly patients after xenon versus propofol anesthesia for major noncardiac surgery: a double-blinded randomized controlled pilot study.

BACKGROUND: Postoperative cognitive dysfunction (POCD) in elderly patients after noncardiac surgery is a common problem. The noble gas xenon has been demonstrated to exert substantial neuroprotective properties in animal studies. Therefore, this study was designed to assess POCD after xenon anesthesia in comparison to propofol in elderly patients undergoing major noncardiac surgery. METHODS: After approval of the local ethical committee was obtained, 101 patients (American Society of Anesthesiologists physical status I-III; age, 65-83 yr) undergoing elective abdominal or urologic surgery (duration, > 2 h) were enrolled into this randomized, double-blinded controlled pilot study. Patients received anesthesia with sufentanil and either propofol or xenon and were assessed before treatment and 1, 6, and 30 days after treatment using a neuropsychological test battery based on previous studies investigating POCD. RESULTS: There were no significant differences in terms of age, American Society of Anesthesiologists status, education, duration of surgery, administered analgetics, and preoperative neurocognitive status between study groups. POCD as classified was present in 22 patients (44%) of the xenon group versus 25 patients (50%) of the propofol group 1 day after treatment, in 6 xenon patients (12%) versus 9 propofol patients (18%) 6 days after treatment, and in 3 xenon patients (6%) versus 6 propofol patients (12%) 30 days after treatment. These differences were not statistically significant. CONCLUSION: Postoperative impairment of neurocognitive function was observed in a substantial proportion of elderly patients even 30 days after treatment. Xenon-based anesthesia was not associated with decreased incidence of POCD in comparison to propofol.

Influence of increased intra-abdominal pressure on fluid responsiveness predicted by pulse pressure variation and stroke volume variation in a porcine model.

OBJECTIVE: Dynamic variables of fluid responsiveness such as pulse pressure variation (PPV) and stroke volume variation (SVV) have been shown to reliably predict the response to fluid administration in different patient populations. The influence of increased intra-abdominal pressure (IAP) on the predictive ability of these variables is currently under debate. Therefore, the present study was designed to evaluate whether PPV and SVV are suitable for predicting fluid responsiveness during elevated IAP. DESIGN: Prospective controlled experimental study. SETTING: Animal research laboratory. SUBJECTS: 14 anesthetized and mechanically ventilated pigs. INTERVENTIONS: Pigs were studied at different experimental stages: normovolemia at baseline conditions, after induction of pneumoperitoneum (PP) by increasing IAP up to 25 mm Hg, followed by releasing PP and performing a fluid load with 1000 cc hydroxyl-ethyl starch 6%, and finally after inducing PP again. Cardiac output, stroke volume, central venous pressure, and pulmonary artery occlusion pressure were obtained by pulmonary artery thermodilution. Additionally, global end-diastolic volume (GEDV) was measured by transpulmonary thermodilution. PPV and SVV were monitored continuously by pulse contour analysis. MEASUREMENTS AND MAIN RESULTS: PP induced significant changes in peak airway pressure, esophageal pressure, chest wall compliance, SVV, PPV, central venous pressure, and pulmonary artery occlusion pressure independent of loading conditions. As assessed by receiver operating characteristic curve analysis, PPV, SVV, and GEDV accurately predicted fluid responsiveness before IAP was increased (area under the curve: 0.90, 0.91 and 0.91). A PPV value of >or=11.5%, a SVV value of >or=9.5%, and a GEDV value of or=15%. After increasing IAP, the ability of SVV to predict fluid responsiveness was abolished, whereas it was preserved with both PPV and GEDV, although the threshold value for PPV dramatically increased up to >or=20.5%. CONCLUSIONS: : In this animal model PPV and GEDV proved to be sensitive and specific predictors of fluid responsiveness even during increased IAP.

Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation.

OBJECTIVE: Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B. METHODS: In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h. RESULTS: After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC. CONCLUSIONS: Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.

Heart rate variability-guided prophylactic treatment of severe hypotension after subarachnoid block for elective cesarean delivery.

BACKGROUND: Baseline low-to-high frequency ratio (LF/HF) of heart rate variability predicted hypotension after subarachnoid block (SAB). LF/HF-guided treatment of hypotension with vasopressors or colloids was investigated. METHODS: In 80 women scheduled to undergo cesarean delivery during SAB, LF/HF and systolic blood pressure (SBP) were analyzed. Patients were randomly assigned to a control group (n = 40) or a treatment group (n = 40). Control patients were assigned by their baseline LF/HF to one of two subgroups: LF/HF less than 2.5 or LF/HF greater than 2.5. Treatment patients with baseline LF/HF greater than 2.5 were treated with vasopressor infusion right after SAB (n = 20) or colloid prehydration until LF/HF decreased below 2.5 (n = 20). The incidences of hypotension (SBP < 80 mmHg) and hypertension (SBP > 140 mmHg) were investigated. LF/HF is presented as median and range, and SBP is presented as mean +/- SD. RESULTS: Three of 17 control patients with low baseline LF/HF (1.7 [1.3/1.8]) demonstrated hypotension, and mean SBP remained stable (lowest SBP = 105 +/- 14 mmHg). In contrast, 20 of 23 control patients with high baseline LF/HF (3.8 [3.3/4.8]; P < 0.0001 vs. low baseline LF/HF) demonstrated hypotension after SAB: lowest SBP = 78 +/- 15 mmHg (P < 0.0001 vs. lowest SBP of control group with low baseline LF/HF). LF/HF-guided vasopressor therapy prevented hypotension in 19 of 20 patients: baseline SBP = 123 +/- 15 mmHg, lowest SBP = 116 +/- 17 mmHg. Mean prophylactic colloid infusion of 1,275 +/- 250 ml reduced elevated baseline LF/HF from 5.4 (4.1/7.5) to 1.3 (0.8/1.59) (P < 0.0001). Hypotension was prevented in 17 of 20 patients: baseline SBP = 115 +/- 13 mmHg, lowest SBP = 104 +/- 19 mmHg. No hypertensive episode was recognized. CONCLUSIONS: LF/HF may be a tool to guide prophylactic therapy of patients at high risk for hypotension after SAB. Vasopressor therapy tended to be more effective compared with colloid prehydration.

Heart rate variability predicts severe hypotension after spinal anesthesia.

BACKGROUND: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension. METHODS: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. Seventy patients were studied prospectively, assigned to one of two groups by their low to high frequency ratio (LF/HF) before SA. Sensitivity and specificity of LF/HF for prediction of decrease of SBP greater 20% of baseline were tested. RESULTS: Retrospective analysis showed differences of LF/HF depending on the degree of hypotension after SA. Prospective analysis demonstrated significant differences of SBP after SA depending on baseline LF/HF (mean +/- SD): low LF/HF (1.3 +/- 0.7) = > SBP: 91 +/- 8% of baseline versus high LF/HF (5.5 +/- 2.4) = > SBP: 66 +/- 10% of baseline (P < 0.05). Baseline LF/HF as well as high frequency and proportional decrease of SBP after SA correlated significantly, in contrast to baseline hemodynamic parameters heart rate and SBP. A receiver operator curve characteristic analysis showed a sensitivity and specificity of LF/HF > 2.5 of 85% to predict SBP decrease of greater than 20% of baseline after SA. CONCLUSIONS: Heart rate variability analysis before SA may predict hypotension after SA with high sensitivity and specificity. LF/HF may be a tool to detect patients at high risk of hypotension due to SA. This indicates that the predictive value of LF/HF is superior to established predictors.

Neuroendocrine stress response and heart rate variability: a comparison of total intravenous versus balanced anesthesia.

Attenuating intraoperative stress is a key factor in improving outcome. We compared neuroendocrine changes and heart rate variability (HRV) during balanced anesthesia (BAL) versus total IV anesthesia (TIVA). Forty-three patients randomly received either BAL (sevoflurane/remifentanil) or TIVA (propofol/remifentanil). Depth of anesthesia was monitored by bispectral index. Stress hormones were measured at 7 time points (P1 = baseline; P2 = tracheal intubation; P3 = skin incision; P4 = maximum operative trauma; P5 = end of surgery; P6 = tracheal extubation; P7 = 15 min after tracheal extubation). HRV was analyzed by power spectrum analysis: very low frequency (VLF), low frequency (LF), high frequency (HF), LF/HF ratio, and total power (TP). LF/HF was higher in TIVA at P6 and TP was higher in TIVA at P3-7 (P3: 412.6 versus 94.2; P4: 266.7 versus 114.6; P5: 290.3 versus 111.9; P6: 1523.7 versus 658.1; P7: 1225.6 versus 342.6 ms2)). BAL showed higher levels of epinephrine (P7: 100.5 versus 54 pg/mL), norepinephrine (P3: 221 versus 119.5; P4: 194 versus 130.5 pg/mL), adrenocorticotropic hormone (P2 10.5 versus 7.7; P5: 5.3 versus 3.6; P6: 10.9 versus 5.3; P7: 20.5 versus 7.1 pg/mL) and cortisol (P7: 6.9 versus 3.9 microg/dL). This indicates a higher sympathetic outflow using BAL versus TIVA during ear-nose-throat surgery.

Overlapping induction of anesthesia: an analysis of benefits and costs.

BACKGROUND: Overlapping induction (OI), i.e., induction of anesthesia with an additional team while the previous patient is still in the operating room (OR), was investigated. METHODS: The study period was 60 days in two followed by three ORs during surgical Block Time (7:30 am until 3:00 pm). Patients were admitted the day before surgery and were thus available and did not have surgery that day unless there was a time reduction. Facilities were already constructed. Number of cases, Nonsurgical Time (Skin Suture Finish until next Procedure Start Time), Turnover Time, and Anesthesia Control Time plus Turnover Time were studied. In addition, economic benefit was calculated. RESULTS: Three hundred thirty-five cases were studied. Using OI, the time of care of regularly scheduled cases was shortened, and the number of cases performed within OR Block Time increased (151 to 184 cases; P < 0.05). Nonsurgical Time (in h:min) decreased (1:08 +/- 0:26 to 0:57 +/- 0:18; P < 0.001), Turnover Time decreased (0:38 +/- 0:24 to 0:25 +/- 0:15; P < 0.05), and Anesthesia Control Time plus Turnover Time decreased (0:43 +/- 0:23 to 0:28 +/- 0:18; P < 0.001). Subgroup analysis showed a significant benefit of OI only in three ORs. In three ORs, economic benefit can be gained at a case mix index greater than 0.3 besides additional costs. CONCLUSIONS: Overlapping induction increased productivity and profit despite the expense of additional staff. Subgroup analysis emphasizes the importance of the number of ORs involved in OI.