[Intraoperative guidance of anesthesia: Analgesie Nociception Index (ANI) vs. standard care for hysterectomy under anesthesia with sevoflurane : A randomized controlled simple blinded study on intraoperative opioid consumption, postoperative pain and patient satisfaction]

BACKGROUND

General anesthesia leads to different effects depending on the drugs used (hypnosis, analgesia, muscle relaxation). While there are validated methods for clinical monitoring and control of hypnosis and muscle relaxation in routine anesthesia, the assessment of analgesia is still mainly based on the interpretation of clinical vital parameters, such as heart rate, blood pressure, perspiration or intraoperative movements of the patient. The present clinical study investigated whether the use of a so-called nociception monitor to record the intraoperative need for analgesics is superior to the previous analysis of vital parameters. The analgesia nociception index (ANI; MDoloris, Lille, France) was used, which is one of several nociception monitors currently on the market for recording the sympathicovagal balance. In the case of the ANI, the measurement is based on the analysis of the heart rate variability (HRV) as a function of breathing. The index is given in the form of a dimensionless score between 0 and 100, where 0 stands for a lack of parasympathetic activity and 100 for a very strong parasympathetic activity. According to the manufacturer, a value between 50-70 under anesthesia corresponds to sufficient intraoperative analgesia.

METHODS

This was a clinical prospective randomized study in which 110 patients who underwent laparoscopic hysterectomy under balanced anesthesia using propofol, fentanyl and atracurium for induction and sevoflurane and fentanyl for anesthesia maintenance, were divided into two groups. In the intervention group (ANI group), during the operation analgesics were administered with the aid of the ANI monitor (bolus of 0.1 mg fentanyl if the ANI was < 50), whereas in the comparison group analgesics were administered according to previous clinical parameters (vital parameters, intraoperative defensive movements). The groups were then compared with respect to intraoperative fentanyl consumption (primary outcome), postoperative pain and opioid-induced side effects (measured by the numeric rating scale [NRS]) as well as patient satisfaction on postoperative day 3 (secondary outcome).

RESULTS

The observations showed a higher total intraoperative consumption of fentanyl in the intervention group, due to a significantly higher number of individual doses (0.54 vs. 0.44 mg, p < 0.001). With respect to the other observation points, there were hardly any differences between the groups, neither with respect to the pain score nor the side effects in the recovery room. At most there was a trend towards a slightly lower pain score at the first measurement point in the recovery room (NRS at 15 min). In the patient survey on the postoperative day 3, there was a difference with respect to the subjectively described reduction in vigilance in the ANI group, but not other side effects or overall satisfaction with the pain therapy.

CONCLUSION

In this group of patients the additional use of the ANI monitor for intraoperative control of analgesia led to an increased consumption of fentanyl compared to the comparison group, without having an impact on the postoperative pain score, opioid-induced side effects or patient satisfaction. An optimization of pain therapy through intraoperative use of the ANI monitoring in hysterectomy patients under balanced anesthesia with sevoflurane and fentanyl could therefore not be proven. Transferability of the results to a much older and/or sicker patient collective remains questionable.

[Preclinical management of cardiac arrest-extracorporeal cardiopulmonary resuscitation]

BACKGROUND

The chances of surviving out-of-hospital cardiac arrest (OHCA) are still very low. Despite intensive efforts the outcome has remained relatively poor over many years. In specific situations, new technologies, such as extracorporeal cardiopulmonary resuscitation (eCPR) could significantly improve survival with a good neurological outcome.

OBJECTIVE

Does the immediate restoration of circulation and reoxygenation via eCPR influence the survival rate after OHCA? Is eCPR the new link in the chain of survival?

MATERIAL AND METHODS

Discussion of current study results and guideline recommendations.

RESULTS

The overall survival rates after OHCA have remained at 10-30% over many years. Despite low case numbers more recent retrospective studies showed that an improved outcome can be achieved with eCPR. In selected patient collectives survival with a favorable neurological outcome is possible in 38% of the cases.

CONCLUSION

Survival after cardiac arrest and the subsequent quality of life dependent on many different factors. The time factor, i.e. the avoidance of a no-flow phase and reduction of the low-flow phase is of fundamental importance. The immediate restoration of the circulation and oxygen supply by eCPR can significantly improve survival; however, large randomized, controlled trials are currently not available.

Epidural needle insertion : A large registry analysis

BACKGROUND

Dural puncture, paraesthesia and vascular puncture are the most common complications of epidural catheter insertion. Their association with variation in midline needle insertion depth is unknown.

OBJECTIVE

This study evaluated the risk of dural and vascular punctures and the unwanted events paraesthesia and multiple skin punctures related to midline needle insertion depth.

MATERIAL AND METHODS

A total of 14,503 epidural catheter insertions including lumbar (L1-L5; n = 5367), low thoracic (T7-T12, n = 8234) and upper thoracic (T1-T6, n = 902) insertions, were extracted from the German Network for Regional Anaesthesia registry between 2007 and 2015. The primary outcomes were compared with logistic regression and adjusted (adj) for confounders to determine the risk of complications/events. Results are presented as odds ratios (OR, [95% confidence interval]).

MAIN RESULTS

Midline insertion depth depended on body mass index, sex, and spinal level. After adjusting for confounders increased puncture depth (cm) remained an independent risk factor for vascular puncture (adjOR 1.27 [1.09-1.47], p = 0.002) and multiple skin punctures (adjOR 1.25 [1.21-1.29], p < 0.001). In contrast, dural punctures occurred at significantly shallower depths (adjOR 0.73 [0.60-0.89], p = 0.002). Paraesthesia was unrelated to insertion depth. Body mass index and sex had no influence on paraesthesia, dural and vascular punctures. Thoracic epidural insertion was associated with a lower risk of vascular puncture than at lumbar sites (adjOR 0.39 [0.18-0.84], p = 0.02).

CONCLUSION

Variation in midline insertion depth is an independent risk factor for epidural complications; however, variability precludes use of depth as a reliable guide to insertion in individual patients.

Hypothermia does not influence liver damage and function in a porcine polytrauma model

BACKGROUND

Previous studies revealed evidence that induced hypothermia attenuates ischemic organ injuries after severe trauma. In the present study, the effect of hypothermia on liver damage was investigated in a porcine long term model of multi-system injury, consisting of blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shockMETHODS: In 30 pigs, a standardized polytrauma including blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shock of 45% of total blood volume was induced. Following trauma, hypothermia of 33∘C was induced for 12 h and intensive care treatment was evaluated for 48 h. As outcome parameters, we assessed liver function and serum transaminase levels as well as a histopathological analysis of tissue samples. A further 10 animals served as controls.

RESULTS

Serum transaminase levels were increased at the end of the observation period following hypothermia without reaching statistical significance compared to normothermic groups. Liver function was preserved (p⩽ 0.05) after the rewarming period in hypothermic animals but showed no difference at the end of the observation period. In H&E staining, cell death was slightly increased hypothermic animals and caspase-3 staining displayed tendency towards more apoptosis in hypothermic group as well.

CONCLUSIONS

Induction of hypothermia could not significantly improve hepatic damage during the first 48 h following major trauma. Further studies focusing on multi-organ failure including a longer observation period are required to illuminate the impact of hypothermia on hepatic function in multiple trauma patients.

Pre-operative fluid bolus for improved haemodynamic stability during minor surgery: A prospectively randomized clinical trial

BACKGROUND

Haemodynamic instability during the induction of anaesthesia and surgery is common and may be related to hypovolaemia caused by pre-operative fasting or chronic diuretic therapy. The aim of our prospective, controlled, randomized study was to test the hypothesis that a predefined fluid bolus given prior to general anaesthesia for minor surgery would increase haemodynamic stability during anaesthetic induction.

METHODS

Two hundred and nineteen fairly healthy adult patients requiring minor surgery were enrolled. All received standard treatment, including a pulse contour analysing device for non-invasive measurement of cardiac index. Infusion therapy was started in all patients at induction. The intervention group (106 patients) was randomized to receive an additional fluid bolus of 8 mL/kg Ringer's acetate solution before the induction of anaesthesia. The primary endpoint was the incidence of haemodynamic instability, defined as a significant reduction of blood pressure or cardiac index during induction of anaesthesia.

RESULTS

The interventional group had a lesser incidence of haemodynamic instability during induction (41.5% vs 56.6%, P = .025). This group also had higher cardiac index, stroke volume index, systolic and mean blood pressure and a greater left ventricular end-diastolic area.

CONCLUSIONS

A fluid bolus prior to anaesthesia reduced the incidence of haemodynamic instability during induction of general anaesthesia. The total fluid volume was slightly greater in the intervention group compared to the control group (1370 ± 439 mL vs 1219 ± 483 mL, P = .007). We conclude that a defined fluid bolus can help stabilizing haemodynamics in patients undergoing general anaesthesia.

Intraneural injection of a test dose of local anesthetic in peripheral nerves - does it induce histological changes in nerve tissue?

BACKGROUND & OBJECTIVES

Most anesthesiologists use the injection of a test dose of local anesthetic in order to evaluate the final needle tip position. Thus, the intraneural injection of a full dose can be avoided. The aim of this study was to analyze whether an intraneural injection of a test dose of bupivacaine could trigger histological changes.

METHODS

Intraneural injections under direct vision were performed in 40 brachial plexus nerves in seven anesthetized pigs. Tibial nerves served as positive and negative controls. Two milliliter of bupivacaine 0.5% was injected in three nerves on the left brachial plexus. For control of local anesthetic's toxicity Ringer's solution was applied intraneurally on the right side. After maintaining 48 h of general anesthesia, the nerves were resected. The specimens were processed for histological examination and assessed for inflammation (hematoxylin and eosin stain, CD68-immunohistochemistry) and myelin damage (Kluver-Barrera stain). The degree of nerve injury was rated on a scale from 0 (no injury) to 4 (severe injury).

RESULTS

Statistical analysis showed no significant differences between the bupivacaine group [median (interquartile range) 1 (1-1.5)] and the Ringer's solution group [1 (0.5-2) P = 0.772]. Mild myelin alteration was found in 12.5% of all specimens following intraneural injection, irrespective of the applied substance.

CONCLUSIONS

"In our experimental study, intraneural injection of 2 ml of bupivacaine or Ringer's solution showed comparable mild inflammation. Nevertheless, inflammation can only be prevented by strictly avoiding nerve perforation followed by intraneural injection, as mechanical nerve perforation is a key factor for evolving inflammation.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Phrenic palsy and analgesic quality of continuous supraclavicular vs. interscalene plexus blocks after shoulder surgery

BACKGROUND

Hemidiaphragmatic palsy is a common consequence of the interscalene brachial plexus block. It occurs less commonly with the supraclavicular approach. Register data suggest that the analgesic quality of a supraclavicular blockade is sufficient for arthroscopic shoulder surgery, although data on the post-operative analgesic effect are lacking.

METHODS

After approval by the ethics committee, patients having arthroscopic shoulder surgery under general anaesthesia were randomized to receive a continuous interscalene or supraclavicular blockade. Phrenic nerve function was evaluated through ultrasound examination of the diaphragm in combination with spirometry. Pain scores at rest and activity etc. were determined before catheter insertion, during observation in the post- anaesthesia care unit (PACU) and on post-operative day 1 (POD1). The initial application of 10 ml of ropivacaine 0.2% was followed by continuous application of 4 ml of ropivacaine 0.2%, plus a patient controlled analgesia (PCA) bolus of 4 ml/h.

RESULTS

One hundred and twenty patients were randomized, of which 114 data sets were analysed. Complete hemidiaphragmatic paresis occurred in 43% of the interscalene group vs. 24% in the supraclavicular group during PACU stay. Rates of dyspnoea and hoarseness were similar. Horner's syndrome occurred in 21% of the interscalene but only 3% of the supraclavicular group on POD1. Pain scores were comparable for pain at rest and during stress at each time point.

CONCLUSIONS

This trial showed a significantly greater incidence of phrenic nerve palsy of the interscalene group in PACU, but not on POD1. Post-operative analgesic quality was similar in both groups. Continuous supraclavicular blockade is a suitable alternative to the continuous interscalene technique.

Peripheral nerve blocks on the upper extremity: Technique of landmark-based and ultrasound-guided approaches

The German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI) established an expert panel to develop preliminary recommendations for the application of peripheral nerve blocks on the upper extremity. The present recommendations state in different variations how ultrasound and/or electrical nerve stimulation guided nerve blocks should be performed. The description of each procedure is rather a recommendation than a guideline. The anaesthesiologist should select the variation of block which provides the highest grade of safety according to his individual opportunities. The first section comprises recommendations regarding dosages of local anaesthetics, general indications and contraindications for peripheral nerve blocks and informations about complications. In the following sections most common blocks techniques on the upper extremity are described.

A porcine polytrauma model with two different degrees of hemorrhagic shock: outcome related to trauma within the first 48 h

BACKGROUND

An animal polytrauma model was developed, including trunk and extremity injuries combined with hemorrhagic shock and a prolonged post-traumatic phase. This could be useful for the assessment of different therapeutic approaches during intensive care therapy.

METHODS

A standardized polytrauma including lung contusion, liver laceration and lower leg fracture was applied in 25 pigs. They underwent controlled haemorrhage either with a blood volume loss of 45 % and a median arterial pressure (MAP) <30 mmHg/90 min (group L, n = 15) or a 50 % blood loss of and an MAP <25 mmHg/120 min (group H, n = 10). Five non-traumatized pigs served as a control (group C). Subsequently, intensive care treatment was given for an observational period of 48 h.

RESULTS

Both trauma groups showed signs of shock and organ injury (heart rate, MAP and lactate). The frequency of cardiopulmonary resuscitation (CPR) and lung injury was directly related to the severity of the haemorrhagic shock (CPR-group L: 4 of 15 pigs, group H: 4 of 10 pigs; Respiratory failure-group L: 3 of 13, group H: 3 of 9. There was no difference in mortality between trauma groups.

CONCLUSION

The present data suggest that our model reflects the mortality and organ failure of polytrauma in humans during shock and the intensive care period. This suggests that the experimental protocol could be useful for the assessment of therapeutic approaches during the post-traumatic period.

Focused intraoperative transthoracic echocardiography by anesthesiologists: a feasibility study

BACKGROUND

Focused transthoracic echocardiography (TTE) is frequently used perioperatively for hemodynamic monitoring and diagnosis of cardiovascular instability, but less commonly intraoperatively.

METHODS

To evaluate the feasibility of intraoperative TTE, we enrolled 222 anesthetised patients from August to November 2012 into a prospective observational study. 162 patients underwent TTE examination according to the Focused Assessed Transthoracic Echocardiography (FATE) protocol after positioning and draping for surgery. Sixty additional hemodynamically unstable subjects were examined during anesthesia and surgery. The imaging quality of four FATE views was rated on a scale from 1 (impossible) to 5 (perfect). TTE was assessed as applicable, if at least two of the four basic FATE views were graded 4 or 5, or three views were assessed as grade 3.

RESULTS

Imaging quality was unacceptable in 20 patients, resulting in a feasibility rate of 91% (97.5%-CI 0.86-1, P=0.01). TTE was feasible in hemodynamically unstable subjects (91.7%; 97.5%-CI 0.82-1.0), in orthopedic and trauma patients (>95% respectively, [97.5%-CI 0.83-1]) and in abdominal surgery (78%).

CONCLUSION

TTE can be applied in the operating theatre during surgery, although its use during abdominal surgery is somewhat limited.

Impact of haemorrhagic shock intensity on the dynamic of alarmins release in porcine poly-trauma animal model

PURPOSE

Traumatic insults result in an altered inflammatory response, in which alarmins release has a central role. The impact of haemorrhagic shock intensity on the long-term kinetics of alarmins is not yet fully elucidated. We investigated these aspects in a combined trauma (chest, abdominal, and extremities injury) porcine model with different severities and durations of haemorrhagic shock.

METHODS

After induction of combined trauma (tibia fracture, lung contusion, and liver laceration), haemorrhagic shock was induced at different intensities: moderate haemorrhage (MH; n = 15): mean arterial pressure (MAP) <30 ± 5 mmHg [maximum loss of total blood volume (TBVmax): 45 %] for 90 min, and severe haemorrhage (SH; n = 10): MAP <25 ± 5 mmHg (TBVmax 50 %) for 120 min. Resuscitation was performed using a standardized crystalloid infusion protocol. Animals were mechanically ventilated and underwent ICU-monitoring for 48 h (MH) and 48.5 h (SH). Blood samples were collected over the clinical time course, and systemic levels of serum alarmins [High-Mobility Group Protein B-1 (HMGB-1) and Heat Shock Protein 70 (HSP70)] were measured using an ELISA kit.

RESULTS

Heart rate, systemic blood pressure, lactate, and base excess were significantly altered as a function of haemorrhagic shock in both trauma groups (MH and SH). Systemic HMGB-1 levels were significantly elevated in both trauma groups when compared to the sham group. Haemorrhagic shock severity and duration were positively correlated with HMGB-1 levels and compared to baseline values, concentrations remained significantly increased in SH when compared to MH. On the other hand, we observed a significant decrease in the systemic HSP70 levels of trauma groups (MH, and SH) when compared to the sham group, which was significantly decreased compared to baseline values in SH over the entire time course.

CONCLUSION

Our data show that haemorrhagic shock duration and severity affect the systemic levels of HMGB-1 and HSP70. This early alarmins release after trauma can be used to guide the treatment strategies (e.g. surgical procedures) of polytrauma patients.

[Seeing more : Technical innovations in regional anesthesia]

Visualization and verification are key factors since the implementation of ultrasound-guided regional anesthesia. This article reviews and discusses newer technical innovations in regional anesthesia with regard to optimization of needle guidance, improvements in needle visibility, technical improvements in ultrasound techniques and innovative technologies in regional anesthesia. Clinically available applications are presented as well as experimental tools and techniques with a potential for clinical implementation in the future. Mechanical needle guides are used to improve alignment of needle axis and ultrasound beam axis. Compound imaging technology improves needle visibility in steep needle insertion angles and is already implemented in daily clinical practice. Sonoelastography improves tissue discrimination and detection of small amounts of fluids. Benefits of 3D and 4D ultrasound in regional anesthesia are discussed as well as experimental tools for tissue discrimination, such as optical reflection spectrophotometry.

Transiente neurologische Symptome nach Spinalanästhesie Eine quantitative systematische Übersicht (Metaanalyse) randomisierter kontrollierter Studien

BACKGROUND

Transient neurologic symptoms (TNS) after spinal anesthesia (SPA) is defined as back pain with radiation or dysesthesia in the buttocks, thighs, hips and calves, occurring within 24 h after recovery from otherwise uneventful SPA. The symptoms last for about 1-3 days but neurophysiologic evaluation does not show pathologic findings. The type and the preparation of the local anesthetic drug (baricity, concentration, additives or preservatives) are most often discussed as the underlying cause of TNS.

METHODS

Randomized controlled comparative studies reporting the incidence of TNS were systematically searched. Descriptive statistics are presented summarizing the identified trials and the pooled relative risk (RR), the number-needed-to-harm (NNH) with their 95% confidence intervals (95%-CI) were calculated using a random effects model.

RESULTS

A total of 29 studies with a 2,813 patients fulfilled the inclusion criteria. Summarizing all patients in these trials without further adjustment, the incidence of TNS was 16.9% after lidocaine, 19.1% after mepivacaine, but only 1.1% after bupivacaine and 1.7% after prilocaine. For tetracaine, procaine, and ropivacaine there were too few studies to draw meaningful conclusions. Using meta-analysis techniques these data were confirmed: the pooled relative risk (RR) for suffering from TNS was 6.7-fold higher after lidocaine (95%-CI: 2.5-18) than after SPA with bupivacaine and 5.5-fold higher (95%-CI: 2-15) than after prilocaine. Furthermore, data show that baricity, concentration of the local anesthetic, and addition of vasoconstrictors have no significant influence on the occurrence of TNS.

CONCLUSION

Prilocaine and bupivacaine for SPA are associated with less TNS than lidocaine and mepivacaine. For the other local anesthetics there were not enough comparative trials to give conclusive recommendations.

[Premedication visits in departments of anesthesiology in Hessen. Compilation of organizational and performance portfolios]

BACKGROUND

Many anesthesia departments operate a pre-anesthesia assessment clinic (PAAC). Data regarding organization, equipment and structure of such clinics are not yet available. Information about modern anesthesiology techniques and procedures contributes to a reduction in emotional stress of the patients but such modern techniques often require additional technical hardware and costs and are not equally available.

AIM

This survey examined the current structures of PAAC in the state of Hessen, demonstrated current concepts and associated these with the performance and the portfolio of procedures in these departments.

MATERIAL AND METHODS

An online survey was carried out. Data on structure, equipment, organization and available methods were compiled. In addition, anesthesia department personnel were asked to give individual subjective attitudes toward the premedication work.

RESULTS

Of the anesthesia departments in Hessen 84 % participated in the survey of which 91 % operated a PAAC. A preoperative contact with the anesthesiologist who would perform anesthesia existed in only 19 % of the departments. Multimedia processing concepts for informed consent in a PAAC setting were in general rare. Many modern procedures and anesthesia techniques were broadly established independent of the hospital size. Regarding the individual and subjective attitudes of anesthetists towards the work, the psychological and medical importance of the pre-medication visit was considered to be very high.

CONCLUSION

The PAACs are now well established. This may make economic sense but is accompanied by an anonymization of care in anesthesiology. The high quality, safety and availability of modern anesthesiology procedures and monitoring concepts should be communicated to patients all the more as an expression of trust and high patient safety. These factors can be facilitated in particular by multimedia tools which have as yet only been sparsely implemented in PAACs.

Supplemental single shot femoral nerve block for total hip arthroplasty: impact on early postoperative care, pain management and lung function

BACKGROUND AND AIM

Peripheral regional anesthesia is beneficial in the management of postoperative pain in hip surgery, and can also reduce post-operative care unit (PACU) stay. Its opioid-sparing actions may also be beneficial for respiratory mechanics and pulmonary function. The aim of our pilot study was to evaluate the effect of a supplemental single shot femoral block for elective total hip arthroplasty on early respiratory function and postoperative management within the first 24 postoperative hours.

METHODS

We prospectively studied 80 patients undergoing total hip arthroplasty. Written informed consent was obtained after ethics committee approval. Forty patients were randomLy assigned to receive single shot femoral nerve block (FNB) using 15mL bupivacaine 0.25% and 20 mg clonidine while the remainder received standard treatment without nerve block (STN). Premedication and general anesthesia were standardized. Pulse oximetry saturation and spirometric lung function were measured preoperatively (baseline) and at 0.5 h, 2 h, 6 h and 24 h, after extubation breathing room air. PACU surveillance and postoperative pain therapy was standardized.

RESULTS

Oxygen saturation and spirometry results were significantly better within the FNB group during the first six postoperative hours. Although VAS scores during the PACU stay did not significantly differ between the study groups, PACU discharge criteria were met earlier in the FNB group (116±40 min [mean±SD] vs. 152±47 min in the STN group). The FNB group exhibited significantly lower VAS scores at 6 and 24 hours.

CONCLUSION

Supplemental single shot femoral nerve block for total hip arthroplasty resulted in earlier PACU discharge capability, improved lung function during the first six hours and better pain control within the first 24 postoperative hours.

[Caesarean sections under regional anesthesia: pros and cons of supplementary oxygen]

The routine administration of supplemental oxygen to women undergoing elective caesarean section under regional anesthesia in order to optimize oxygen supply to the fetus is common anesthetic practice in many German hospitals. However, this practice has been controversially discussed in the non-German literature for many years. This review presents and discusses the pros and cons of routinely providing supplemental oxygen to a parturient during caesarean section on the basis of the literature published over the last 30 years. Proponents of routine oxygen administration point to potential and unforeseeable risks of caesarean sections and consider the prophylactic administration of oxygen based on physiological considerations to be advantageous in terms of patient safety. Interestingly, data regarding the effects of an increased maternal FIO2 on improvement of fetal oxygenation are inconsistent, therefore, no unambiguous recommendation concerning which FIO2 to choose can be given. Opponents of routine oxygen supplementation allude above all to an increase in free radical activity in both mother and fetus; however, data in this respect are not consistent either. As supplemental oxygen to patients undergoing elective caesarean section without any risk factors under regional anesthesia is associated with potential risks while no advantage has so far been demonstrated, routine administration of oxygen has to be challenged and is no longer considered to be indicated by many. On the contrary, in cases of emergency with a concomitant risk of hypoxia for mother and fetus, administration of oxygen is indispensable in the light of present data.

A self-sufficient Baeyer-Villiger biocatalysis system for the synthesis of ɛ-caprolactone from cyclohexanol

In order to establish a new route for ɛ-caprolactone production from the corresponding cyclohexanol with an internal cofactor recycling for NADPH, a recently redesigned thermostable polyol dehydrogenase (PDH) and the cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus were combined. First, the expression of PDH could be improved 4.9-fold using E. coli C41 with co-expression of chaperones. Both enzymes were also successfully co-immobilized on glutaraldehyde-activated support (Relizyme™ HA403). Cyclohexanol could be converted to ɛ-caprolactone (ɛ-CL) with 83% conversion using the free enzymes and with 34% conversion using the co-immobilized catalysts. Additionally, a preparative scale biotransformation of ɛ-caprolactone starting from cyclohexanol was performed using the soluble enzymes. The ɛ-CL could be isolated by simple extraction and evaporation with a yield of 55% and a purity of >99%.

Protein engineering of a thermostable polyol dehydrogenase

The polyol dehydrogenase PDH-11300 from Deinococcus geothermalis was cloned, functionally expressed in Escherichia coli and biochemically characterized. The enzyme showed the highest activity in the oxidation of xylitol and 1,2-hexanediol and had an optimum temperature of 45 °C. The enzyme exhibited a T⁶⁰₅₀-value of 48.3 °C. The T⁶⁰₅₀ is the temperature where 50% of the initial activity remains after incubation for 1h. In order to elucidate the structural reasons contributing to thermostability, the substrate-binding loop of PDH-11300 was substituted by the loop-region of a homolog enzyme, the galactitol dehydrogenase from Rhodobacter sphaeroides (PDH-158), resulting in a chimeric enzyme (PDH-loop). The substrate scope of this chimera basically represented the average of both wild-type enzymes, but surprisingly the T⁶⁰₅₀ was noticeably increased by 7 °C up to 55.3 °C. Further mutations in the active site led to identification of residues crucial for enzyme activity. The cofactor specificity was successfully altered from NADH to NADPH by an Asp55Asn mutation, which is located at the NAD⁺ binding cleft, without influencing the catalytic properties of the dehydrogenase.

Efficacy and safety of 10% HES 130/0.4 versus 10% HES 200/0.5 for plasma volume expansion in cardiac surgery patients

AIM

Hydroxyethyl starch (HES) solutions are frequently used for perioperative volume replacement. Whereas older HES specimen tended to accumulate in the plasma and to cause negative effects on hemostasis, more recent products, e.g., HES 130/0.4, are characterised by improved pharmacological properties. The present study was designed to compare the efficacy and safety of 10% HES 130/0.4 and 10% HES 200/0.5.

METHODS

In this post-hoc analysis of a prospective, randomised, double-blind, multi-center therapeutic equivalence trial, 76 patients undergoing elective on-pump cardiac surgery received perioperative volume replacement using either 10% HES 130/0.4 (N.=37) or 10% HES 200/0.5 (N.=39) up to a maximum dose of 20 mL kg-1.

RESULTS

Equivalent volumes of investigational medication were infused until 24 hours after the first administration (1577 vs. 1540 mL; treatment difference 37 [-150; 223] mL; P<0.0001 for equivalence). Whereas standard laboratory tests of coagulation were comparable between groups, von Willebrand factor activity on the first postoperative morning tended to be higher following treatment with 10% HES 130/0.4 as compared to 10% HES 200/0.5 (P=0.025) with this difference being statistically significant only in the per-protocol analysis (P=0.02). Treatment groups were comparable concerning other safety parameters and the incidence of adverse drug reactions. In particular, renal function was well preserved in both groups.

CONCLUSION

Ten percent HES 130/0.4 was equally effective and safe as compared to 10% HES 200/0.5 for volume therapy in patients undergoing cardiovascular surgery. Postoperative coagulation and renal function, as measured by standard laboratory tests, were similar among groups.

A comparison of desflurane versus propofol: the effects on early postoperative lung function in overweight patients

BACKGROUND

In this study, we evaluated the influence of propofol versus desflurane anesthesia in overweight patients on postoperative lung function and pulse oximetry values.

METHODS

We prospectively studied 134 patients with body mass indices of 25 to 35 kg/m(2) undergoing minor peripheral surgery lasting 40 to 120 minutes. Patients were randomly assigned to receive propofol (total IV anesthesia) or desflurane anesthesia via a tracheal tube targeting bispectral index values of 40 to 60. Premedication, adjuvant drug usage, and ventilation were standardized. We measured oxyhemoglobin saturation and lung function preoperatively (baseline), and at 10 minutes, 0.5 hour, 2 hours, and 24 hours after tracheal extubation. All values were measured with the patient supine, in a 30° head-up position. Changes from preoperative baseline values were first analyzed for the impact of body mass index and type of anesthesia using univariate methods, followed by linear regression and multivariate analysis of variance.

RESULTS

Within the first 2 hours after surgery, the propofol group displayed lower oxyhemoglobin saturation (at 2 hours, mean ± SD, 93.8% ± 2.0% vs 94.6% ± 2.1%; P < 0.007) and lung function (forced vital capacity, forced expiratory volume exhaled in 1 second [FEV(1)], peak expiratory flow, midexpiratory flow [MEF], forced inspiratory vital capacity, and peak inspiratory flow; between 11% and 20% larger reduction from baseline in the propofol group, all P < 0.001) compared with the desflurane group. Even 24 hours after surgery, FEV(1), peak expiratory flow, MEF, forced inspiratory vital capacity, and peak inspiratory flow were reduced more in the propofol group (all P < 0.01). At 2 hours after extubation, increasing obesity was associated with decreasing FEV(1) and MEF in patients anesthetized with propofol but not desflurane (P < 0.01).

CONCLUSION

We conclude that, for superficial surgical procedures of up to 120 minutes, maintenance of anesthesia with propofol impairs early postoperative lung function and pulse oximetry values more than with desflurane. Furthermore, increasing obesity decreases pulmonary function at 2 hours after propofol anesthesia but not after desflurane anesthesia.

Nerve perforation with pencil point or short bevelled needles: histological outcome

BACKGROUND

In the case of needle nerve contact during peripheral blocks, pencil point needles are considered less traumatic compared with bevelled needles. However, there are not enough data to prove this notion. Therefore, the aim of this study was to challenge the hypothesis that nerve perforation with short bevelled needles is associated with major nerve damage compared with pencil point needles.

METHODS

In five anaesthetised pigs, the brachial plexus was exposed bilaterally. Up to eight nerves underwent needle nerve perforation using a pencil point needles cannula or an short bevelled needle. After 48 h, the nerves were resected. The specimens were processed for visual examination and the detection of inflammatory cells (haematoxylin-eosin, i.e. CD68-immunohistochemistry to detect macrophages), myelin damage (Kluver-Barrera staining) and intraneural haematoma. The grade of nerve injury was characterised by an objective score ranging from 0 (no injury) to 4 (severe injury).

RESULTS

Fifty nerves were examined. According to the injury score applied, there was no significant difference between the pencil point needles [median (inter-quartile range) 2.0 (2.0-2.0)] and the short bevelled-needle group [median 2.0 (2.0-2.0) P=0.23]. No myelin damage was observed. Signs of post-traumatic inflammation were equally distributed among both groups.

CONCLUSIONS

In the present study, the magnitude of nerve injury after needle nerve perforation was not related to one of the applied needle types. Post-traumatic inflammation rather than structural damage of nerve tissue is the only notable sign of nerve injury after needle nerve perforation with either needle type. However, neither the pencil point- nor the short bevelled needle can be designated a less traumatic device.

Systematic evaluation of the highest current threshold for regional anaesthesia in a porcine model

BACKGROUND

The purpose of this study was to determine systematically the highest minimal stimulation current threshold for regional anaesthesia in pigs.

METHODS

In an established pig model for regional anaesthesia, needle placements applying electric nerve stimulation were performed. The primary outcome was the frequency of close needle to nerve placements as assessed by resin injects and subsequent anatomical evaluation. Following a statistical model (continual reassessment method), the applied output currents were selected to limit the necessary number of punctures, while providing guidance towards the highest output current range.

RESULTS

Altogether 186 punctures were performed in 11 pigs. Within the range of 0.3-1.4 mA, no distant needle to nerve placement was found. In the range of 1.5-4.1 mA, 43 distant needle to nerve placements occurred. The range of 1.2-1.4 mA was the highest interval that resulted in a close needle to nerve placement rate of > or =95%.

CONCLUSIONS

In the range of 0.3-1.4 mA, all resin deposition was found to be adjacent to nerve epineurium. The application of minimal current intensities up to 1.4 mA does not obviously lead to a reduction of epineural injectate contacts in pigs. These findings suggest that stimulation current thresholds up to 1.4 mA result in equivalent needle tip localisation in pigs.

Postoperative analgesia with parecoxib, acetaminophen, and the combination of both: a randomized, double-blind, placebo-controlled trial in patients undergoing thyroid surgery

BACKGROUND

We assessed the analgesic efficacy of parecoxib, acetaminophen, and the combination of both compared with placebo in patients undergoing elective thyroid or parathyroid surgery.

METHODS

We randomized 140 patients to receive one of the following i.v. treatments using a double-blinded double-dummy technique: placebo, 80 mg 24 h(-1) parecoxib, 5 g 24 h(-1) acetaminophen, or 80 mg parecoxib plus 5 g acetaminophen. We provided rescue analgesia with piritramide delivered by a patient-controlled analgesia device. We measured opioid consumption and pain intensity over 24 h after operation.

RESULTS

Patient characteristic data, anaesthetic, and surgical characteristics of the patients in the four groups were similar. Parecoxib, acetaminophen, and the combination significantly reduced opioid requirements during 24 h after surgery [mean (sd) 12.5 (10.9) mg for parecoxib, 14.2 (12.3) mg for acetaminophen, and 11.9 (10.7) mg for combination] compared with placebo [23.5 (15.3) mg, P<0.05]. However, the combination of parecoxib and acetaminophen did not have any advantage over individual drugs in terms of opioid consumption in our trial (P>0.05).

CONCLUSIONS

Parecoxib and acetaminophen effectively reduce postoperative opioid requirements after thyroid or parathyroid surgery. The combination of these drugs is not associated with a further reduction in opioid consumption.

[Risk of interrupting nocturnal nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnea]

Patients with obstructive sleep apnea are at risk of respiratory and cardiovascular complications (e.g. hypoxia, hypertensive crisis, cardiac ischemia and arrhythmias) as a result of airway callapse during the perioperative period. Therefore it is essential that the nasal continuous airway pressure (nCPAP-therapy) be maintained during that time. Such patients and the medical staff should be aware of this problem.

Femoral nerve block with ropivacaine or bupivacaine in day case anterior crucial ligament reconstruction

BACKGROUND/OBJECTIVE

Our aim was to evaluate analgesia, motor block and pharmacokinetics of ropivacaine 0.2% and 0.75% in a femoral nerve block (FNB) in day case patients for anterior crucial ligament (ACL)-reconstruction compared with bupivacaine 0.25% and placebo.

METHODS

Following ethics committee approval and informed consent, 280 patients were randomly allocated to four groups for single-shot FNB [30 ml ropivacaine 0.2% (group RO2.0), 0.75% (RO7.5), bupivacaine 0.25% (BU2.5) and NaCl 0.9% (NaCl)]. Analgesia (pain scores, primary outcome) and motor block were assessed at 4 h (dismissal) and up to 24 h. Plasma concentration was determined up to 240 min thereafter.

RESULTS

Pain scores at 4 h were significantly higher for NaCl 4 (0-8) (median, range) (vs.) BU2.5 2 (0-8), RO2.0 3 (0-9) and RO7.5 2 (0-8) (NS within the LA groups). Patients of the NaCl group needed analgesics significantly more often (93%) within 4 h after surgery vs. 16% of group RO2.0, 19% of group RO7.5 and 19% of group BU2.5. Motor block was significantly increased with all local anesthetics without a significant difference within the LA groups 3 (0-5) in RO2.0, 3 (0-5) in RO7.5 and 3 (0-4) in BU2.5 vs. 0 (0-3) in group NaCl (median (range); scale from 0=full strength to 5=complete paralysis). Peak plasma concentrations differed significantly: RO7.5: 1.4 +/- 0.4 (0.73-2.6) [microg/ml, mean +/- SD (range)] after 33 +/- 14 (10-40) min, RO2.0: 0.6 +/- 0.3 (0.13-1.0) after 22+17 (10-60) and BU2.5: 0.3 +/- 0.16 (0.05-0.62) at 31 +/- 17 (10-60), respectively.

CONCLUSION

FNB for ACL reconstruction with ropivacaine or bupivacaine provided better post-operative analgesia than placebo without reaching toxic plasma concentrations. Significant motor block was observed after 4 h in all groups including the lowest concentration of ropivacaine but occurred even with placebo.

High or low current threshold for nerve stimulation for regional anaesthesia

BACKGROUND

The purpose of this study was to determine whether the application of high stimulation current thresholds (SCT) leads to a distant needle to nerve proximity (NNP) compared with low SCT during nerve localization for regional anaesthesia in pigs.

METHODS

A minimal motor response to the stimulation of femoral or brachial plexus nerves in 16 anaesthetized pigs was triggered either by a minimal SCT of a low (0.01-0.3 mA) or a high (0.8-1.0 mA) current in a random order. After eliciting a motor response with a predetermined SCT, synthetic resin was injected via the needle. After postmortem dissection of the injection site, the localization of the resin deposition was determined verifying the final position of the needle tip. Depending on the proximity of resin deposition to the nerve epineurium, the needle tip placement was considered either as a close or a distant NNP.

RESULTS

A total of 235 punctures were performed. Ninety-one punctures were carried out with low SCT and 92 with a high SCT. Fifty-two punctures served as a control (1.8-2.0 mA). All injectates following both high or low SCT were considered 'close needle tip to nerve placement', whereas 27 of 52 injectates of the control group appeared distant to nerve epineurium.

CONCLUSION

Regardless of the applied SCT, i.e. high or low, all resin deposition was found adjacent to nerve epineurium. These findings suggest that high and low SCT result in equivalent needle tip localization in pigs.

[Local and regional anaesthesia. Principles and techniques]

Local and regional anaesthesia procedures are common in most surgical practices. Continuous regional anaesthesia techniques may improve the outcome and significantly reduce postoperative pain. Epidural anaesthesia is recommended for abdominal and thoracic surgery, whereas continuous peripheral regional anaesthesia via a catheter is advantageous for limb surgery. Although these techniques are very safe, emergency treatment of life-threatening complications must be available.

[Perioperative management of patients suffering from sleep-related breathing disorders]

Sleep-related breathing disorders have been associated with increased perioperative morbidity and mortality. The respective patients are at risk during two independent periods. Besides an early period, characterised by the influence of anaesthetics, patients are at risk also during a late period, which is characterised by nocturnal desaturation and disturbances of the cardiovascular system, caused by interference with the sleep architecture, especially of the REM sleep. To assure a safe perioperative management, a close monitoring (O2 saturation and pCO2) and the option for non-invasive ventilation have to be guaranteed.

Comparison between intubation and the laryngeal mask airway in moderately obese adults

BACKGROUND

Obesity is a well-established risk factor for perioperative pulmonary complications. Anaesthetic drugs and the effect of obesity on respiratory mechanics are responsible for these pathophysiological changes, but tracheal intubation with muscle relaxation may also contribute. This study evaluates the influence of airway management, i.e. intubation vs. laryngeal mask airway (LMA), on postoperative lung volumes and arterial oxygen saturation in the early postoperative period.

METHODS

We prospectively studied 134 moderately obese patients (BMI 30) undergoing minor peripheral surgery. They were randomly assigned to orotracheal intubation or LMA during general anaesthesia with mechanical ventilation. Premedication, general anaesthesia and respiratory settings were standardized. While breathing air, we measured arterial oxygen saturation by pulse oximetry. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 0.5, 2 and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P<0.05.

RESULTS

Postoperative pulmonary mechanical function was significantly reduced in both groups compared with preoperative values. However, within the first 24 h, lung function tests and oxygen saturation were significantly better in the LMA group (P<0.001; ANOVA).

CONCLUSIONS

In moderately obese patients undergoing minor surgery, use of the LMA may be preferable to orotracheal intubation with respect to postoperative saturation and lung function.