[Tracheal rupture following endotracheal intubation for an emergency cesarean]. / Trachealriss nach Intubation bei Notsectio.

This is a case report of a 45-year-old patient, 39 weeks of gestation, who was intubated via rapid sequence induction (RSI) for an emergency cesarean. The indication for emergency cesarean was a pathological cardiotocography during the ejection phase following labor induction.Despite the primary use of a video laryngoscope, there was difficulty aligning the laryngeal axis. Therefore, an internal stylet was used to heavily angulate the endotracheal tube (ETT) to a hockey stick shape to enter the larynx.Postoperative dyspnea and extensive facial swelling were initially diagnosed as an allergic reaction. Only 22 h later the diagnosis of tracheal rupture was confirmed following computer tomography.We hypothesized that the mechanism of injury was due to excessive pressure transmitted to the tip of the ETT. This probably occurred due to a leverage effect caused by the withdrawal of the heavily bent stylet from the ETT, forcing an intratracheal cranial movement of the ETT.By conducting an experiment on a pig's trachea, we were able to visualize this mechanism of injury. In addition, we were able to demonstrate that bending the stylet to a similar angle as the laryngoscope blade led to minimal movement of the tip of the ETT.Therefore, when using a stylet during intubation, we recommend bending the ETT and stylet to the shape of the used laryngoscope blade and retracting the stylet at a similar angle to avoid complications, such as tracheal rupture.

[Iatrogenic anisocoria after using a scopolamine patch for PONV prophylaxis]. / Iatrogene Anisokorie nach Scopolaminpflaster zur PONV-Prophylaxe.

This is a case report of a 29-year-old female patient who developed unilateral mydriasis following the use of a scopolamine patch for the prevention of postoperative nausea and vomiting (PONV).Given a medical history showing multiple risk factors for PONV, a preauricular scopolamine patch was applied prior to the induction of anesthesia. General anesthesia was induced with 150 mg propofol and 25 µg sufentanil and maintained with total intravenous anesthesia, using propofol (5 mg/kg per h) and remifentanil (2-3 µg/kg per h).Following an uneventful surgery of 90min duration, the patient was extubated and transferred to the recovery room, where the patch was removed. During the orthopedic ward round the following day, the clinical examination revealed anisocoria of the left eye in the form of unilateral mydriasis. In order to determine the cause of this clinical presentation, further neurological and ophthalmological examinations and investigations were carried out. In addition, magnetic resonance imaging was conducted to rule out a central nervous cause. The results of the investigations were negative and no pathology was identified. In addition, the symptoms resolved within 24 h of onset without any therapeutic intervention. Therefore, a suspected diagnosis of a pharmacologically induced anisocoria from the scopolamine patch was made, whereby the substance accidentally reached the affected left eye.Previous studies showed that scopolamine patches may reduce early emetic symptoms. Case reports describing the occurrence of anisocoria following the application of scopolamine patches have been previously published. In all of these cases the patches were used to prevent PONV and each case was comprehensively investigated using various diagnostic and clinical tools. It should be noted, however, that a dysfunctional accommodation is listed as a common side effect of the drug, affecting more than 1 in 10 patients.Even though the efficacy of scopolamine patches for the prevention of PONV is proven, clinicians should be aware of the common ophthalmological side effect. Particularly with respect to various surgical disciplines, where anisocoria may indicate an underlying surgery-related complication, the application of scopolamine patches should be well- considered.

Is internal jugular vein extensibility associated with indices of fluid responsiveness in ventilated patients?

BACKGROUND: Ultrasound of the inferior vena cava provides rapid and non-invasive assessment of fluid responsiveness. We hypothesized that the extensibility of the internal jugular vein (IJV) as well reflects intravascular volume state. We assessed IJV dimensions together with pulse pressure variation (PPV) as dynamic index for fluid responsiveness in mechanically ventilated patients. METHODS: Of 50 patients after cardiac surgery were assessed. Ultrasound of IJV dimensions as well as collection of hemodynamic data were performed in 30° and horizontal (0°) position, and the ventilator- and position-induced IJV extensibilities (E-IJV) were calculated. RESULTS: Mean ventilator-induced E-IJV in 30° position was 56%, and mean PPV in 30° position was 13.7%. Changing the patient's position from 30° to 0° significantly reduced ventilator-induced E-IJV as well as PPV. Pearson's correlation test revealed significant association between ventilator-induced E-IJV and fluid responsiveness deduced from PPV in 0° position (r = 0.43, P < 0.005). An E-IJV threshold >5% identified patients with significantly elevated PPV values. CONCLUSION: Ultrasound of the IJV and PPV as a dynamic index for fluid responsiveness can be associated under certain defined conditions. Whether or not ultrasound of the IJV can be useful to predict patient intravascular volume state should be further studied using invasive cardiac output monitoring.

[Pediatric emergence agitation]. / Postoperative Agitation im Kindesalter.

BACKGROUND: The origin of emergence agitation in children remains unclear; however, an association between surgical procedure, patient age and anesthetic regimen and the incidence of postoperative agitation has been described in the literature. AIM: The aim of this survey performed between February and April 2014 was to collect data from the daily clinical practice by experienced pediatric anesthesiologists regarding documentation, premedication, anesthesia regimen and postoperative treatment with respect to children with emergence agitation. MATERIAL AND METHODS: An online questionnaire with 33 items was developed and sent to all 525 members of the scientific committee of pediatric anesthesia (WAKKA) of the German Society of Anesthesiology and Intensive Care (DGAI). Members were asked to respond within a time period of 1 month but no reminders were sent out via email or telephone. RESULTS: A total of 156 members participated in the survey and of these 143 questionnaires were fully completed and included in the final evaluation (27 %). Of the participants 77 % had more than 6 years professional experience in the field of pediatric anesthesia and for 87 % emergence agitation remains a relevant clinical problem. The estimated incidence of emergence agitation was given as 1-10 % and as high as 11-20 % by 56% and 20 % of the participants, respectively. The incidence of postoperative agitation is documented by only 11 % of the participants with a validated score, such as the pediatric anesthesia emergence delirium (PEAD) scale and 89 % of the participants use midazolam for premedication. As a preemptive intervention total intravenous anesthesia is performed by 56 % whereas clonidine is used as first line prevention by 30 %. Postoperative pharmacological treatment is performed by a bolus administration of propofol (56 %) and clonidine (26 %). Postoperative parental presence was considered beneficial by 82 %. CONCLUSION: Emergence agitation is still seen as a relevant clinical problem by experienced pediatric anesthesiologists. Propofol is first choice when it comes to pharmacological prevention and treatment of emergence agitation. Postoperative parental presence was considered beneficial by the majority of anesthesiologists.

Bilateral bispectral index monitoring during and after electroconvulsive therapy compared with magnetic seizure therapy for treatment-resistant depression.

BACKGROUND: Electroconvulsive therapy (ECT) is a highly effective and established treatment for depression. Magnetic seizure therapy (MST) has recently been developed and seems equally effective while associated with fewer side-effects. Both require general anaesthesia, which could be quantified using the bispectral index (BIS). We compared ECT and MST with respect to recovery times, left-sided BIS, and left-right differences in BIS. METHODS: In this prospective, observational study, we enrolled 10 successive patients receiving ECT and 10 patients undergoing MST. Anaesthesia was performed with propofol and monitored with a bilateral BIS sensor. The seizure was elicited when the BIS was within a range from 50 to 60. The time to eye opening was measured and bilateral BIS were recorded for 10 min after seizure induction. RESULTS: A comparable anaesthetic depth was observed in the ECT and MST groups at baseline [mean (standard deviation, sd) BIS values of 94.1 (4.1) and 95.5 (3.0), respectively] and before seizure induction [mean (sd) BIS values of 52.3 (9.6) and 55.2 (10.3), respectively]. Post-ictally, MST patients opened their eyes significantly earlier than ECT patients [3.0 (1.0) vs 6.7 (1.3) min, P<0.001]. They showed a significantly higher BIS at 2 min after seizure induction [69.2 (10.1) vs 50.9 (15.9), P=0.003], and this difference was still present at 10 min after seizure induction [BIS 81.5 (6.5) vs 68.0 (16.4), P<0.001]. Significant differences between the left and right BIS were observed in neither the ECT nor the MST group. CONCLUSIONS: At a comparable anaesthetic depth, MST is superior to ECT in terms of post-ictal recovery, which is correctly reflected by higher post-ictal BIS values. Unilateral BIS monitoring is sufficient to monitor anaesthetic depth in ECT and MST patients. TRIAL REGISTRY NUMBER: NCT 01318018.

Patient state index vs bispectral index as measures of the electroencephalographic effects of propofol.

BACKGROUND: The patient state index (PSI) and the bispectral index (BIS) quantify anaesthetic depth based on the EEG using different algorithms. We compared both indices with regard to the prediction of the depth of propofol anaesthesia. METHODS: In 17 patients, propofol was infused until burst suppression occurred and stopped thereafter until BIS recovered to values above 60. This was repeated; afterwards, patients were intubated, for subsequent surgery. Without surgical stimulus, PSI and BIS were measured simultaneously and compared with the estimated effect-site concentrations of propofol. These were derived from simultaneous pharmacokinetic and -dynamic modelling in an individual two-stage and a population-based NONMEM approach. RESULTS: A close sigmoid relationship was observed between the propofol effect-site concentration and both PSI [coefficient of determination rho(2)=0.91 (sd 0.05)] and BIS [rho(2)=0.92 (0.03)], which was significantly steeper for PSI [gamma=2.2 (0.6)] than for BIS [gamma=1.8 (0.4)], and reached significantly lower values for PSI [E(max)=0.3 (1.1)] than for BIS [E(max)=5.3 (6.7)] at maximal propofol concentrations. A significantly smaller k(e0) was obtained for PSI [0.09 (0.03) min(-1)] compared with BIS [0.10 (0.02) min(-1)]. PSI and BIS correlated significantly with each other (rho(2)=0.866) and predicted propofol effect-site concentration with a comparable probability [P(K)=0.87 (0.05) and 0.86 (0.05), respectively]. NONMEM revealed E(0)=89.3 and 92.3, E(max)=1.9 and 8.6, C(e50)=1.38 and 1.92 microg ml(-1), gamma=1.6 and 1.48, and k(e0)=0.103 and 0.131 min(-1) as typical values for PSI and BIS, respectively. CONCLUSIONS: The PSI and the BIS monitors performed equally well in predicting depth of propofol anaesthesia. However, PSI was lower than BIS by approximately 10-15 points at high propofol concentrations.

The Entropy Module and Bispectral Index as guidance for propofol-remifentanil anaesthesia in combination with regional anaesthesia compared with a standard clinical practice group.

This study was designed to investigate the impact of the Entropy Module and Bispectral Index (BIS) monitoring on drug consumption and recovery times compared with standard anaesthetic practice in patients undergoing orthopaedic surgery using a combination of regional and general anaesthesia as performed by an experienced anaesthesiologist. We hypothesised that electroencephalogram monitoring would lead to a lower drug consumption as well as shorter recovery times. With institutional review board approval and written informed consent, 90 adult patients undergoing surgery to the upper or lower extremity received regional anaesthesia for post- and intraoperative pain control and were randomised to receive general anaesthesia by propofol/remifentanil infusion controlled either solely by clinical parameters or by targeting Entropy or BIS values of 50. Recovery times and drug consumption were recorded. Data from 79 patients were analysed. Compared with standard practice, patients with Entropy or BIS monitoring showed a similar propofol consumption (standard practice 101 +/- 22 microg/kg/minute, Entropy 106 +/- 24 microg/kg/minute, BIS 104 +/- 20 microg/kg/minute) and showed similar Aldrete scores (10/10) one minute after extubation: 9.1 +/- 0.3, 9.2 +/- 0.6 and 9.3 +/- 0.5, respectively. Time points of extubation were 7.3 +/- 2.9 minutes, 9.2 +/- 3.9 minutes and 6.8 +/- 2.9 minutes, respectively, demonstrating a significant difference between Entropy and BIS (P = 0.023). Compared with standard practice, targeting an Entropy or BIS value of 50 did not result in a reduction of propofol consumption during general anaesthesia combined with regional anaesthesia as performed by an experienced anaesthesiologist in orthopaedic patients.

Reduction in anaesthetic drug consumption is correlated with mean titrated intra-operative Bispectral Index values.

BACKGROUND: Several studies have shown a reduction in anaesthetic drug consumption with Bispectral Index (BIS) titration compared with standard clinical practice. However, the amount of reduction varied widely between 1% and 40%. We investigated the correlation between reduction in anaesthetic drug consumption and mean titrated BIS values. METHODS: An analysis upon randomized controlled trials cited until January 2006 in MEDLINE and other databases investigating the potential reduction in anaesthetic (hypnotic) drug consumption with BIS titration was performed. Investigations with a marked difference (> 15%) in opioid drug consumption between the BIS group and the standard practice group were excluded. Correlations between amount of reduction in hypnotic drug use and the mean titrated BIS value were analysed with linear regression. RESULTS: Fourteen manuscripts covering 2582 patients were included into the analysis. The mean BIS value in the standard clinical practice group averaged over all studies was 43.6 +/- 3.2 and the mean BIS value in the BIS-titrated group was 49.9 +/- 5.4. The amount of reduction in hypnotic drug use correlated significantly with the mean BIS values in the BIS-titrated groups (r =0.68) and with the differences between the mean BIS value in the BIS-titrated group and the mean BIS value in the standard clinical practice group (r = 0.70). Every point of BIS difference between the two groups resulted in a reduced hypnotic drug use of approximately 2%. CONCLUSION: Despite differences in the study designs and in the drugs used, a linear correlation between the mean titrated BIS value and the hypnotic drug saving potential was found.

Correlation of the A-Line ARX index with acoustically evoked potential amplitude.

BACKGROUND: Automated indices derived from mid-latency auditory evoked potentials (MLAEP) have been proposed for monitoring the state of anaesthesia. The A-Line ARX index (AAI) has been implemented in the A-Line monitor (Danmeter, V1.4). Several studies have reported variable and, in awake patients, sometimes surprisingly low AAI values. The purpose of this study was to reproduce these findings under steady-state conditions and to investigate their causes. METHODS: Ten awake unmedicated volunteers were studied under steady-state conditions. For each subject, the raw EEG and the AAI were recorded with an A-Line monitor (V1.4) during three separate sessions of 45.0 (1.6) min duration each. MATLAB (Mathworks) routines were used to derive MLAEP responses from EEG data and to calculate maximal MLAEP amplitudes. RESULTS: The AAI values ranged from 15 to 99, while 11.4% fell below levels which, according to the manufacturer, indicate an anaesthetic depth suitable for surgery. Inter-individual and intra-individual variation was observed despite stable recording conditions. The amplitudes of the MLAEP varied from 0.8 to 42.0 microV. The MLAEP amplitude exceeded 2 microV in 75.3% of readings. The Spearman's rank correlation coefficient between the MLAEP amplitude and the AAI value was r=0.89 (P<0.0001). CONCLUSIONS: The version of the A-Line monitor used in this study does not exclude contaminated MLAEP signals. Previous publications involving this version of the A-Line monitor (as opposed to the newer A-Line/2 monitor series) should be reassessed in the light of these findings. Before exclusively MLAEP-based monitors can be evaluated as suitable monitors of depth of anaesthesia, it is essential to ensure that inbuilt validity tests eliminate contaminated MLAEP signals.

Molecular and functional changes in voltage-dependent Na(+) channels following pilocarpine-induced status epilepticus in rat dentate granule cells.

Status epilepticus (S.E.) is known to lead to a large number of changes in the expression of voltage-dependent ion channels and neurotransmitter receptors. In the present study, we examined whether an episode of S.E. induced by pilocarpine in vivo alters functional properties and expression of voltage-gated Na(+) channels in dentate granule cells (DGCs) of the rat hippocampus. Using patch-clamp recordings in isolated DGCs, we show that the voltage-dependent inactivation curve is significantly shifted toward depolarizing potentials following S.E. (half-maximal inactivation at -43.2+/-0.6 mV) when compared with control rats (-48.2+/-0.8 mV, P<0.0001). The voltage-dependent activation curve is significantly shifted to more negative potentials following S.E., with half-maximal activation at -28.6+/-0.8 mV compared with -25.8+/-0.9 mV in control animals (P<0.05). The changes in voltage dependence resulted in an augmented window current due to increased overlap between the activation and inactivation curve. In contrast to Na(+) channel voltage-dependence, S.E. caused no changes in the kinetics of fast or slow recovery from inactivation. The functional changes were accompanied by altered expression of Na(+) channel subunits measured by real-time reverse transcription-polymerase chain reaction in dentate gyrus microslices. We investigated expression of the pore-forming alpha subunits Na(v)1.1-Na(v)1.3 and Na(v)1.5-Na(v)1.6, in addition to the accessory subunits beta(1) and beta(2). The Na(v)1.2 and Na(v)1.6 subunit as well as the beta(1) subunit were persistently down-regulated up to 30 days following S.E. The beta(2) subunit was transiently down-regulated on the first and third day following S.E. These results indicate that differential changes in Na(+) channel subunit expression occur in concert with functional changes. Because coexpression of beta subunits is known to robustly shift the voltage dependence of inactivation in a hyperpolarizing direction, we speculate that a down-regulation of beta-subunit expression may contribute to the depolarizing shift in the inactivation curve following S.E.

Slow recovery from inactivation regulates the availability of voltage-dependent Na(+) channels in hippocampal granule cells, hilar neurons and basket cells.

1. Fundamental to the understanding of CNS function is the question of how individual neurons integrate multiple synaptic inputs into an output consisting of a sequence of action potentials carrying information coded as spike frequency. The availability for activation of neuronal Na(+) channels is critical for this process and is regulated both by fast and slow inactivation processes. Here, we have investigated slow inactivation processes in detail in hippocampal neurons. 2. Slow inactivation was induced by prolonged (10-300 s) step depolarisations to -10 mV at room temperature. In isolated hippocampal dentate granule cells (DGCs), recovery from this inactivation was biexponential, with time constants for the two phases of slow inactivation tau(slow,1) and tau(slow,2) ranging from 1 to 10 s and 20 to 50 s, respectively. Both (slow,1) and tau(slow,2) were related to the duration of prior depolarisation by a power law function of the form tau(t) = a (t/a)b, where t is the duration of the depolarisation, a is a constant kinetic setpoint and b is a scaling power. This analysis yielded values of a = 0.034 s and b = 0.62 for tau(slow,1) and a = 24 s and b = 0.30 for tau(slow,2) in the rat. 3. When a train of action potential-like depolarisations of different frequencies (50, 100, 200 Hz) was used to induce inactivation, a similar relationship was found between the frequency of depolarisation and both tau(slow,1) and tau(slow,2) (a = 0.58 s, b = 0.39 for tau(slow,1) and a = 3.77 s and b = 0.42 for tau(slow,2)). 4. Using nucleated patches from rat hippocampal slices, we have addressed possible cell specific differences in slow inactivation. In fast-spiking basket cells a similar scaling relationship can be found (a = 3.54 s and b = 0.39) as in nucleated patches from DGCs (a = 2.3 s and b = 0.48) and non-fast-spiking hilar neurons (a = 2.57 s and b = 0.49). 5. Likewise, comparison of human and rat granule cells showed that properties of ultra-slow recovery from inactivation are conserved across species. In both species ultra-slow recovery was biexponential with both tau(slow,1) and tau(slow,2) being related to the duration of depolarisation t, with a = 0.63 s and b = 0.44 for tau(slow,1) and a = 25 s and b = 0.37 for tau(slow,2) for the human subject. 6. In summary, we describe in detail how the biophysical properties of Na(+) channels result in a complex interrelationship between availability of sodium channels and membrane potential or action potential frequency that may contribute to temporal integration on a time scale of seconds to minutes in different types of hippocampal neurons.