P Marhofer

Medical University of Vienna, Wien, Vienna, Austria

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Publications (130)390.61 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous data have indicated the efficacy of dexmedetomidine as an additive to peripheral regional anaesthesia. There are no pharmacodynamic data regarding the addition of dexmedetomidine to local anaesthetics for perineural administration. The objective of this study is to assess the dose-dependency of dexmedetomidine when injected with ropivacaine for peripheral nerve blockade. A prospective, randomised, triple-blind, controlled study in volunteers. Department of Clinical Pharmacology, Medical University of Vienna. Twenty-four volunteers. All volunteers received an ulnar nerve block with 22.5 mg ropivacaine alone (R), or mixed with 50 (RD50), 100 (RD100) or 150 μg (RD150) dexmedetomidine. The primary outcome was the duration of complete sensory block to pinprick and time to complete recovery of pinprick. Secondary outcomes included block success and onset time, motor block, haemodynamic parameters and sedation level. There was a significant dose-dependent (P < 0.0001) increase in the mean duration (SD) of sensory block with dexmedetomidine: R: 8.7 (1.5) h, RD50: 16.4 (4.0) h, RD100: 20.4 (2.8) h and group RD150: 21.2 (1.7) h. Sedation was also enhanced in a dose-dependent (P < 0.001) manner. Two volunteers each receiving 150 μg dexmedetomidine had postblock paraesthesia for 72 h. Dexmedetomidine mixed with ropivacaine produces a dose-dependent prolongation of sensory block and clinically relevant dose-dependent sedation. Dexmedetomidine 100 μg may represent a balance between efficacy and sedation.
    European Journal of Anaesthesiology 02/2015; DOI:10.1097/EJA.0000000000000246 · 3.01 Impact Factor
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    ABSTRACT: Our aim was to review the recent evidence for the efficacy of peripheral regional anaesthesia. Following a systematic literature search and selection of publications based on prospectively agreed upon criteria, we produced a narrative review of the most commonly performed peripheral regional anaesthetic blocks for surgery on the upper limb, the lower limb, and the trunk. We considered short-term and longer-term benefits and complications among the outcomes of interest. Where good quality evidence exists, the great majority of the blocks reviewed were associated with one or any combination of reduced postoperative pain, reduced opioid consumption, or increased patient satisfaction. For selected surgical procedures, the use of blocks avoided general anaesthesia and was associated with increased efficiency of the surgical pathway. The exceptions were supraclavicular block, where there was insufficient evidence, and transversus abdominis plane block, where the evidence for efficacy was conflicting. The evidence for the impact of the blocks on longer-term outcomes was, in general, inadequate to inform clinical decision making. Permanent complications are rare. The majority of peripheral regional anaesthetic techniques have been shown to produce benefits for patients and hospital efficiency. Further interventional trials are required to clarify such benefits for supraclavicular block and transversus abdominis plane block and to ascertain any longer-term benefits for almost all of the blocks reviewed. Permanent complications of peripheral regional anaesthetic blocks are rare but accurate estimates of their incidence are yet to be determined. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    BJA British Journal of Anaesthesia 02/2015; 114(5). DOI:10.1093/bja/aeu559 · 4.35 Impact Factor
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    ABSTRACT: Previous results in volunteers have indicated the effective dose in 99% of subjects (ED99) of local anaesthetic volume to be 0.10 ml.mm−2 of cross-sectional nerve area for sciatic nerve blockade. The objective of this prospective, randomised, double-blind study was to investigate the ED99 of local anaesthetic for ultrasound-guided sciatic nerve blockade in patients undergoing foot surgery, according to Dixon's up-and-down method and probit analysis. A starting volume of 0.20 ml local anaesthetic per mm2 cross-sectional nerve area was used. If surgical anaesthesia was judged to be adequate, the volume of local anaesthetic for the next case was reduced by 0.02 ml.mm−2, until the first block failed. Thereafter, the volume of local anaesthetic was increased by 0.02 ml.mm−2. The ED99 volume of local anaesthetic for ultrasound-guided sciatic nerve blockade was calculated to be 0.15 ml.mm−2 cross-sectional nerve area, which is higher than the previously evaluated ED99 volume in volunteers.
    Anaesthesia 01/2015; 70(5). DOI:10.1111/anae.13013 · 3.85 Impact Factor
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    ABSTRACT: Effective pain therapy after shoulder surgery is the main prerequisite for safe management in an ambulatory setting. We evaluated adverse events and hospital re-admission using a database of 509 interscalene catheters inserted during ambulatory shoulder surgery. Adverse events were recorded for 34 (6.7%) patients (9 (1.8%) catheter dislocations diagnosed in the recovery room, 9 (1.8%) catheter dislocations at home with pain, 2 (0.4%) pain without catheter dislocation, 1 (0.2%) 'secondary' pneumothorax without intervention and 13 (2.6%) other). Twelve (2.4%) patients were re-admitted to hospital (8 (1.6%) for pain, 2 (0.4%) for dyspnoea and 2 (0.4%) for nausea and vomiting), 9 of whom had rotator cuff repair. A well-organised infrastructure, optimally trained medical professionals and appropriate patient selection are the main prerequisites for the safe, effective implementation of ambulatory interscalene catheters in routine clinical practice.
    Anaesthesia 09/2014; 70(1). DOI:10.1111/anae.12840 · 3.85 Impact Factor
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    ABSTRACT: The current literature provides fundamental insights regarding the neurotoxic potency of various general anesthetic drugs in neonates and small infants. Therefore, considerations to minimize the use of general anesthetic drugs in this age group are required. The use of caudal and epidural anesthesia under sedation is one possibility to minimize the use of general anesthetic drugs. A large number of surgical procedures can be managed with this anesthetic concept. Training, practical hand skills, good infrastructure, a well-defined indication, and a team approach including the entire operation room staff are the major prerequisites to implement these techniques in the daily clinical practice. This review article discusses all present aspects and possible future evolutions of caudal and epidural anesthesia under sedation.
    Pediatric Anesthesia 09/2014; 25(1). DOI:10.1111/pan.12543 · 1.74 Impact Factor
  • 08/2014; 12(1):37-38. DOI:10.1080/22201173.2006.10872431
  • P Marhofer, P-A Lönnqvist
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    ABSTRACT: Optimal pain therapy during the perioperative period or at the neonatal intensive care unit and subsequent reduced use of opioids and various sedative drugs is an important factor for patients care. The use of various regional anaesthetic techniques in experienced hands provides excellent pain relief and has the potency to reduce the requirement for perioperative mechanical ventilation. Most of regional anaesthesia techniques are applicable also in neonates and young infants and can be used in an effective and safe manner. Ultrasound guidance should be used for all regional anaesthetic techniques to increase efficacy and safety. The spectrum of indications for ultrasound-guided regional anaesthesia in babies and infants are surgery, selective pain therapy and sympathicolysis. This review reflects an expert-based description of the most recent developments in ultrasound-guided regional anaesthetic techniques in babies and infants.
    Acta Anaesthesiologica Scandinavica 07/2014; 58(9). DOI:10.1111/aas.12372 · 2.31 Impact Factor
  • Christian Breschan, Peter Marhofer
    Pediatric Anesthesia 03/2014; 24(3):344-5. DOI:10.1111/pan.12333 · 1.74 Impact Factor
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    ABSTRACT: /st>The relation between the pattern of local anaesthetic (LA) spread and the quality of peripheral nerve block is unclear. /st>Twenty-one volunteers were randomized to receive a median nerve block with intended circumferential or intended non-circumferential spread of LA. Different predetermined volumes and needle placement techniques were used to produce the different patterns of LA spread. Volumetric, multiplanar 3D ultrasound imaging was performed to evaluate the pattern and extent of LA spread. Sensory block was assessed at predetermined intervals. /st>Complete circumferential spread of LA was achieved in only 67% of cases in the intended circumferential study group and in 33% of cases in the intended non-circumferential group. Block success was similar (90%) and independent of whether circumferential or non-circumferential spread of the LA was achieved. All block failures (n=4) occurred in the intended non-circumferential group with low volumes of LA. The onset of sensory block (independent of group allocation) was faster with circumferential spread of LA [median (IQR) onset time, 15 (8; 20) min] compared with non-circumferential spread of LA [median (IQR) onset time, 20 (15; 30) min]. More LA was used for circumferential blocks [median (IQR) volume of LA 2.8 (1.3; 3.6) vs 1.3 (1.1; 2.4) ml]. /st>Even under optimal conditions, it was not possible to achieve circumferential spread of LA in all intended cases. The success of median nerve block seems to be independent of the pattern of LA spread.Clinical trial registrationDRKS 00003826.
    BJA British Journal of Anaesthesia 02/2014; 113(1). DOI:10.1093/bja/aeu002 · 4.35 Impact Factor
  • Survey of Anesthesiology 01/2014; 58(3):146. DOI:10.1097/01.SA.0000446361.21773.12
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    ABSTRACT: Many skills needed to provide patients with safe, timely, and adequate anesthesia care during humanitarian crisis and disaster relief operations are not part of the daily routine before deployment. An exploratory study was conducted to identify preparedness, knowledge, and skills needed for deployment to complex emergencies. Anesthesiologists who had been deployed during humanitarian crisis and disaster relief operations completed an online questionnaire assessing their preparedness, skills, and knowledge needed during deployment. Qualitative data were sorted by frequencies and similarities and clustered accordingly. Of 121 invitations sent out, 55 (46%) were completed and returned. Of these respondents, 24% did not feel sufficiently prepared for the deployment, and 69% did not undertake additional education for their missions. Insufficient preparedness involved equipment, drugs, regional anesthesia, and related management. As the lack of preparation and relevant training can create precarious situations, anesthesiologists and deploying agencies should improve preparedness for anesthesia personnel. (Disaster Med Public Health Preparedness. 2013;0;1-5).
    Disaster Medicine and Public Health Preparedness 08/2013; 7(4):408-412. DOI:10.1017/dmp.2013.40 · 1.14 Impact Factor
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    ABSTRACT: In neonates, infants and young children, central venous catheters are of vital importance during surgery as well as postoperative care. However, percutaneous catheter insertion in infants and children is a challenge even for the experienced anaesthetist. The benefit of ultrasound seems to be very important because of the smaller size of the vessels and the inability of these patients to cooperate without anaesthesia. Ultrasound-guided cannulation increases the overall success rate by reducing the time to the successful vessel puncture and by decreasing the complication rate in comparison to the landmark-guided technique. Ultrasound (US) may be used for cannulation of the internal jugular (IJV), subclavian (SCV), brachiocephalic (BCV), and femoral (FV) veins. In this review we will present a brief description of US for central venous access, an overview of the different puncture sides with their benefits and pitfalls, and the recent recommendations regarding the routine use of US for central vessel puncture in paediatric patients.
    08/2013; 3(4):188–192. DOI:10.1016/j.tacc.2013.03.008
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    ABSTRACT: Background and Objectives In particular obese patients may profit from peripheral regional anaesthesia due to avoidance of general anaesthesia. Currently ultrasound guidance is described as the golden standard in regional anaesthesia, but no studies have so far evaluated the ultrasound behaviour of peripheral nerve structures in obese versus normal weight patients. To be able to perform such studies it is necessary to develop new and more objective methods to quantify nerve visibility by ultrasound. We therefore designed a prospective, observational, comparative and blinded study to investigate the visibility of peripheral nerves in obese versus normal weight patients by using a novel method based on histogram grey scale values.Methods We scanned the median and sciatic nerves in forty obese and normal weight female patients and calculated differences of histogram grey scale values between nerves and surrounding tissues.ResultsHistogram value analysis showed less ultrasound visibility of sciatic nerves in obese versus normal weight study patients which is caused by higher surrounding tissue histogram values. No differences could be detected for median nerves.Conclusions The novel technique of comparing histogram grey scale values to determine the visibility of peripheral nerve in different patient categories was found feasible. Median nerves are appropriately visible by ultrasound in both normal and obese subjects whereas sciatic nerves are less visible in obese as compared with normal-weight women. Our results serve as the rationale behind difficulties in peripheral regional anaesthesia in obese patients.International Journal of Obesity accepted article preview online, 25 June 2013; doi:10.1038/ijo.2013.119.
    International journal of obesity (2005) 06/2013; DOI:10.1038/ijo.2013.119 · 5.39 Impact Factor
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    ABSTRACT: BACKGROUND: /st>Dislocation rates of continuous peripheral nerve block are poorly described even though this technique is frequently used in clinical practice. The present study was designed to evaluate dislocation rates over time of interscalene and femoral nerve catheters under defined experimental circumstances. Ultrasound (US) monitoring was used to detect the position of the perineural catheters. METHODS: /st>Twenty volunteers received US-guided interscalene and femoral nerve catheters. The volunteers performed standardized physical exercises in regular intervals and the position of both catheters was examined by US confirmation of the spread of fluid. The maximal time of investigation in each volunteer was 6 h. The main outcome parameters were the overall dislocation rates and the cumulative dislocation rates at a given time point. RESULTS: /st>We observed an overall dislocation rate of 15% (5% for interscalene catheters, 25% for femoral nerve catheters) and a significant correlation between time and rate of dislocations (r=0.99, P=0.001). US visualization of the spread of fluid was possible in all cases. CONCLUSIONS: /st>This is the first dedicated evaluation of dislocation rates of peripheral nerve catheters (PNCs) via US investigation. Both movement and time are considerable factors for perineural catheter displacement. US is useful for the performance of PNCs and for the continuous detection of the spread of fluid relative to the nerve and adjacent anatomical structures. Translational research is required to confirm the study results in the clinical practice.German Clinical Trials RegisterDRKS00003494.
    BJA British Journal of Anaesthesia 06/2013; 111(5). DOI:10.1093/bja/aet198 · 4.35 Impact Factor
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    ABSTRACT: BACKGROUND:: This study was designed to examine the spread of local anesthetic (LA) via magnetic resonance imaging after a standardized ultrasound-guided thoracic paravertebral blockade. METHODS:: Ten volunteers were enrolled in the study. We performed ultrasound-guided single-shot paravertebral blocks with 20 ml mepivacaine 1% at the thoracic six level at both sides on two consecutive days. After each paravertebral blockade, a magnetic resonance imaging investigation was performed to investigate the three-dimensional spread of the LA. In addition, sensory spread of blockade was evaluated via pinprick testing. RESULTS:: The median (interquartile range) cranial and caudal distribution of the LA relative to the thoracic six puncture level was 1.0 (2.5) and 3.0 (0.75) [=4.0 vertebral levels] for the left and 0.5 (1.0) and 3.0 (0.75) [=3.5 vertebral levels] for the right side. Accordingly, the LA distributed more caudally than cranially. The median (interquartile range) number of sensory dermatomes which were affected by the thoracic paravertebral blockade was 9.8 (6.5) for the left and 10.7 (8.8) for the right side. The sensory distribution of thoracic paravertebral blockade was significantly larger compared with the spread of LA. CONCLUSIONS:: Although the spread of LA was reproducible, the anesthetic effect was unpredictable, even with a standardized ultrasound-guided technique in volunteers. While it can be assumed that approximately 4 vertebral levels are covered by 20 ml LA, the somatic distribution of the thoracic paravertebral blockade remains unpredictable. In a significant percentage, the LA distributes into the epidural space, prevertebral, or to the contralateral side.
    Anesthesiology 02/2013; 118(5). DOI:10.1097/ALN.0b013e318289465f · 6.17 Impact Factor
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    ABSTRACT: BACKGROUND: /st>Dexmedetomidine is an α-2-receptor agonist which might be used as an additive to local anaesthetics for various regional anaesthetic techniques. We therefore designed this prospective, double-blinded, controlled volunteer study to investigate the effects of dexmedetomidine as an adjuvant to ropivacaine on peripheral nerve block. METHODS: /st>Ultrasound-guided ulnar nerve block (UNB) was performed in 36 volunteers with either 3 ml ropivacaine 0.75% (R), 3 ml ropivacaine 0.75% plus 20 µg dexmedetomidine (RpD), or 3 ml ropivacaine 0.75% plus systemic 20 µg dexmedetomidine (RsD). UNB-related sensory and motor scores were evaluated. RESULTS: /st>Sensory onset time of UNB was not different between the study groups, whereas motor onset time was significantly faster in Group RpD when compared with the other study groups [mean (sd)] [21 (15) vs 43 (25) min in Group RsD and 47 (36) min in Group R, P<0.05 Group RpD vs other groups]. The duration of sensory block was 350 (54) min in Group R, 555 (118) min in Group RpD, and 395 (40) min in Group RsD (P<0.01 Group RpD vs other groups, P<0.05 Group RsD vs Group R). Motor block duration was similar to the duration of sensory block. CONCLUSIONS: /st>A profound prolongation of UNB of ∼60% was detected with perineural dexmedetomidine when added to 0.75% ropivacaine. The systemic administration of 20 µg dexmedetomidine resulted in a prolongation of ∼10% during UNB with 0.75% ropivacaine.Eudra-CT No.: 2012-000030-19.
    BJA British Journal of Anaesthesia 11/2012; 110(3). DOI:10.1093/bja/aes400 · 4.35 Impact Factor
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    ABSTRACT: Regional anesthesia in children is an evolving technique with many advantages in perioperative management. Although most regional anesthesia techniques are sufficiently described in the literature, the implementation of these techniques into daily clinical practice is still lacking. The main problems associated with pediatric regional anesthesia (PRA) include the appropriate selection of blockade, the management around the block, and how to teach these techniques in an optimal manner. This review article provides an overview of these 'hot' topics in PRA.
    Pediatric Anesthesia 10/2012; 22(10):995-1001. DOI:10.1111/pan.12003 · 1.74 Impact Factor
  • Resuscitation 10/2012; 83:e87. DOI:10.1016/j.resuscitation.2012.08.225 · 3.96 Impact Factor
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    ABSTRACT: Despite caudal blockade being the most widely used regional anaesthetic procedure for infants and children undergoing subumbilical surgery, the question whether the injection velocity of the local anaesthetic itself affects its spread in the epidural space has not yet been investigated. Thus, the aim of the present study was to measure the cranial spread of caudally administered local anaesthetics in infants and children by means of real-time ultrasonography, with a special focus on comparing the effect of using two different speeds of injection. Fifty ASA I-II infants and children, aged up to 6 yr, weighing up to 25 kg, undergoing subumbilical surgery, were enrolled in this prospective, randomized, observer-blinded study. Caudal blockade was performed under ultrasound observation using ropivacaine 1 ml kg(-1) 0.2% or 0.35% and an injection given at either 0.25 ml s(-1) or 0.5 ml s(-1), respectively. Ultrasound observation of the local anaesthetic flow and the extent of cranial spread was possible in all patients. All caudal blocks were considered successful, and all surgical procedures could be completed without any indications of insufficient analgesia. No statistically significant difference could be observed between the two injection speeds regarding the cranial spread of the local anaesthetic in the epidural space. The main finding of the present study is that the speed of injection of the local anaesthetic does not affect its cranial spread during caudal blockade in infants and children. Therefore, the prediction of the cranial spread of the local anaesthetic, depending on the injection speed, is not possible.
    BJA British Journal of Anaesthesia 02/2012; 108(4):670-4. DOI:10.1093/bja/aer502 · 4.35 Impact Factor
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    ABSTRACT: The establishment of peripheral venous access in infants is the most common invasive technique in paediatric anaesthesia. Venous puncture can be challenging due to the small size of vessels in this patient population. The present study was designed to investigate the practicability of ultrasound-guided vascular access to the great saphenous vein (GSV) at the level of the medial malleolus in infants ≤ 12 months. Ninety consecutive infants ≤ 12 months undergoing elective surgery were included in this prospective study and divided into two age groups (0-6 and 7-12 months). After anaesthesia induction with sevoflurane, an ultrasound investigation of both GSVs at the level of the medial malleoli was performed. Subsequently, venous access in one GSV was established under direct ultrasound control. Anatomical ultrasound data and success rates of venous accesses were analysed. While not deeper relative to the skin, the GSV was significantly larger in older infants. The success rate in infants ≤ 6 months was 96%, whereas in older infants, the success rate was 100%. The overall success rate in all infants was 98%. Ultrasound facilitates venous puncture of the GSV in the vast majority of infants ≤ 12 months. Direct visualization via ultrasound is a promising technique for the establishment of venous access in the GSV at the level of the medial malleolus in infants.
    BJA British Journal of Anaesthesia 02/2012; 108(2):290-4. DOI:10.1093/bja/aer334 · 4.35 Impact Factor

Publication Stats

4k Citations
390.61 Total Impact Points

Institutions

  • 2000–2015
    • Medical University of Vienna
      Wien, Vienna, Austria
  • 2014
    • IST Austria
      Klosterneuberg, Lower Austria, Austria
  • 2007
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands
    • University of Toronto
      • Department of Anesthesia
      Toronto, Ontario, Canada
  • 2006
    • Karolinska University Hospital
      Tukholma, Stockholm, Sweden
  • 2005–2006
    • University of Cape Town
      • Department of Anaesthesia
      Kaapstad, Western Cape, South Africa
  • 1997–2005
    • University of Vienna
      • Department of Anaesthesiology and General Intensive Care
      Wien, Vienna, Austria