Michael Malcharek

Perioperative Anesthesiological Management of Patients with Pulmonary Hypertension

Pulmonary hypertension is a major reason for elevated perioperative morbidity and mortality, even in noncardiac surgical procedures. Patients should be thoroughly prepared for the intervention and allowed plenty of time for consideration. All specialty units involved in treatment should play a role in these preparations. After selecting each of the suitable individual anesthetic and surgical procedures, intraoperative management should focus on avoiding all circumstances that could contribute to exacerbating pulmonary hypertension (hypoxemia, hypercapnia, acidosis, hypothermia, hypervolemia, and insufficient anesthesia and analgesia). Due to possible induction of hypotonic blood circulation, intravenous vasodilators (milrinone, dobutamine, prostacyclin, Na-nitroprusside, and nitroglycerine) should be administered with the greatest care. A method of treating elevations in pulmonary pressure with selective pulmonary vasodilation by inhalation should be available intraoperatively (iloprost, nitrogen monoxide, prostacyclin, and milrinone) in addition to invasive hemodynamic monitoring. During the postoperative phase, patients must be monitored continuously and receive sufficient analgesic therapy over an adequate period of time. All in all, perioperative management of patients with pulmonary hypertension presents an interdisciplinary challenge that requires the adequate involvement of anesthetists, surgeons, pulmonologists, and cardiologists alike.

Safety of resuscitation with Ringer's acetate solution in severe burn (VolTRAB)—An observational trial

BACKGROUND A variety of crystalloids are available during fluid resuscitation of the severely burnt patient. There is a paucity of literature evidence on the comparative influence of these with regard to clinical outcomes. Significant differences in crystalloids may be clinically relevant given the large volumes employed during shock resuscitation. METHODS The study compared two groups of severely burnt patients (TBSA 20-70%). Prospectively 40 consecutive patients treated with Ringers acetate (RA group) against a retrospective control group of 40 patients treated with Ringers lactate (RL group). Outcome parameters analysed included Sequential Organ Failure Assessment (SOFA)-scores at Days 3 and 7 after injury, mortality at 28 and 60 days, electrolyte and renal function, infection rates, cumulative volume administration and duration of ventilator support. RESULTS Groups RA and RL were comparable w.r.t. age, total body surface area burn size and ABSI. SOFA-scores on Day 1 of admission also showed no significant difference but were significantly lower in RA group between the 3rd and 6th day. By Day 7 these differences could be attributed as a group effect (P=0.019). In particular low cardiovascular organ function scores contributed to this. Total crystalloid use within the first 28 days were equal in both but differed within the RA group having lower observed volumes of colloid and incidence of blood transfusion. Furthermore group RA had distinctly higher levels of platelets throughout treatment. Elevated lactate levels were noted in RL group during the initial three days. Survival rates at 28 days and 60 days showed no significant difference. CONCLUSION Ringers acetate solution is a suitable medium for the initial fluid management of the acutely burnt patient. In comparison to Ringers lactate solution the study revealed lower SOFA-scores for Ringers acetate solution (ClinicalTrials.gov number, NCT00609700).

Transcranial motor evoked potentials during anesthesia with desflurane versus propofol--A prospective randomized trial.

OBJECTIVE This study aimed to evaluate differences in transcranial electrical motor evoked potential (tcMEP) amplitudes between desflurane/remifentanil and propofol/remifentanil anesthesia treatment plans in patients without preexisting motor deficits (PMDs) undergoing carotid endarterectomy (CEA). METHODS This prospective trial included 21 patients who were randomly assigned to an effect group (Group(DESFLURANE); n=14) or a control group (Group(STANDARD-PROPOFOL); n=7). tcMEP amplitudes were measured 35 min post-induction (T1) either with desflurane or propofol. Treatment was then changed to propofol in Group(DESFLURANE). After an additional 35 min, the tcMEP amplitudes were reevaluated (T2). Differences in amplitudes (DW) between T1 and T2 were calculated for each patient, and the means of these differences were compared between groups. RESULTS tcMEPs were recorded in all 21 patients. At T1, the mean amplitude was 840.1 (SD 50.3) μV and 358.9 (SD 74) μV for Group(STANDARD-PROPOFOL) and Group(DESFLURANE), respectively. The absolute mean difference (T1-T2) between groups was -496.75 μV (p=0.0006). CONCLUSION Desflurane reduces the tcMEP amplitude significantly more than propofol in patients without PMDs undergoing CEA. SIGNIFICANCE TcMEPs were recorded in all patients regardless of the anesthesia regimen. In patients with initially small amplitudes, desflurane may limit tcMEP recording because it produces a remarkable amplitude reduction, even in patients without PMDs.

Intraoperative multimodal evoked potential monitoring during carotid endarterectomy: a retrospective study of 264 patients.

BACKGROUND:Methods for detecting intraoperative cerebral ischemia arising from internal carotid artery (ICA) cross-clamping during carotid endarterectomy (CEA) should be sensitive, specific, and rapid to prevent intraoperative stroke. We had 3 objectives pertaining to this: (1) investigation of the rates of success of multimodal evoked potential (mEP) monitoring using a combination of median nerve (m) somatosensory (SS) EPs, tibial nerve SSEPs (tSSEPs), and transcranial electrical stimulated motor EPs (tcMEPs); (2) evaluation of the rates of false-negative mEP results; and (3) analysis of the relationship between different time periods associated with ICA cross-clamping and the postoperative outcome of motor function in patients with significant changes in mEP monitoring. METHODS:Two hundred sixty-four patients undergoing CEA using general anesthesia with monitoring of bilateral mSSEPs, tSSEPs, and tcMEPs were retrospectively reviewed between 2009 and 2012. The rates of successful assessment of mEPs were investigated, and the rate of false-negative mEP results was analyzed. Different time periods (T1—time of clamping, T2—clamping to significant mEP changes, T3—significant mEP change to intervention, and T4—intervention to recovery of EP) were tested using Welch t test for significant association with postoperative motor deficit. RESULTS:(1) Multimodal EP monitoring was achieved in 241 patients (91.3%, point estimate [PE] 0.91, confidence interval [CI] 0.87 to 0.94), whereas none of the modalities were recordable in one case (PE 0.0038, CI 0.0002 to 0.019). Additionally, tSSEP was not recordable in 21 patients (PE 0.08, CI 0.05 to 0.12), and we found one case of isolated failure of tcMEP recording (PE 0.0038, CI 0.0002 to 0.019). (2) False-negative mEP results were found in 1 patient (0.4%; PE 0.0038, CI 0.0002 to 0.019). Significant mEP changes occurred in 32 patients (12.1%), and thus, arterioarterial shunt was performed in 17 (6.4%) patients. Eleven patients (4.2%) showed transient and 1 showed permanent postoperative motor deficit. (3) There was no significant difference regarding any of the time periods associated with ICA cross-clamping and postoperative alteration of motor function (T1: P = 0.19, CI −30.1 to 6.8 minutes; T2: P = 0.38, CI −23 to 9.5 minutes; T3: P = 0.25, −9.7 to 2.8 minutes; T4: P = 0.42, CI to −15.5 to 7.0 minutes). CONCLUSIONS:Multimodal EP monitoring is applicable during CEA. The 0.4% false-negative rate suggests an advantage of mEP monitoring when compared with isolated mSSEP monitoring. Our data suggest that periods of time during cross-clamping were not significantly associated with postoperative motor deficit. However, the small number of patients limits the conclusiveness of these findings. mEP monitoring could not prevent a postoperative motor deficit in all patients, but our results suggest that it is a useful adjunct to mSSEP monitoring.

Comparison of Enk Fibreoptic Atomizer with translaryngeal injection for topical anaesthesia for awake fibreoptic intubation in patients at risk of secondary cervical injury: A randomised controlled trial.

BACKGROUND Two methods of topical anaesthesia for awake fibreoptic intubation (FOI) in patients at risk of secondary cervical injury were compared: the translaryngeal injection (TLI) technique and the Enk Fibreoptic Atomizer. OBJECTIVE The objective of this study was to determine which system of topical anaesthesia provides the fastest and most comfortable awake FOI, using the oral approach. DESIGN A randomised controlled study. SETTING A single centre trial between 2009 and 2011. PATIENTS One hundred and twenty patients (63 women, 57 men) who underwent neurosurgery of the spine at Klinikum St. Georg Leipzig were randomly allocated into two groups (groupTLI, 61 patients; groupENK-ATOMIZER, 59 patients). Inclusion criteria were an American Society of Anesthesiology (ASA) physical status of 1 to 3, age 18 to 80 years, and those who met any one of three indications for FOI - cervical instability, predicted difficult airway, a BMI greater than 40 kg m−2, and who gave written informed consent. Exclusion criteria were emergency awake FOI, mental disability/delirium, polytrauma and contraindication to TLI. INTERVENTIONS Two anaesthesiologists experienced in both techniques performed all anaesthesia procedures within the study. MAIN OUTCOME MEASURES The primary outcome was the timing sequence of awake FOI. The incidence of coughing/gagging, ease of tracheal tube placement, mucosal bleeding, cardiopulmonary stability and postoperative outcomes were also investigated. RESULTS Awake FOI was significantly faster using the TLI technique (mean, 191 s; range, 123 to 447 s; SD, 83.5) than the Enk Fibreoptic Atomizer [mean, 430 s; range, 275 to 773 s; SD, 124.9; (P = 0.0001)]. Patients in groupTLI exhibited significantly less gagging (P = 0.047) but more mucosal bleeding (P < 0.001). CONCLUSION Awake FOI using the TLI technique was faster and provided better topical anaesthesia with less gagging during endoscopic intubation. However, the TLI technique was also more invasive. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT00948350

Recordings of long-latency trigeminal somatosensory-evoked potentials in patients under general anaesthesia

OBJECTIVE The reliability of intra-operative recordings of trigeminal scalp-induced somatosensory-evoked potentials (T-SSEP) is controversial. This investigation aimed to provide evidence that T-SSEP recordings are stable using standardised neurophysiological methodology and anaesthesiological regime. METHODS We investigated 99 patients undergoing carotid endarterectomy under total intravenous anaesthesia (propofol/remifentanil infusion). Long-latency T-SSEPs were recorded from the scalp after simultaneously stimulating 2nd and 3rd branches of the trigeminal nerve. The analysis included visual assessments of traces and measurements of latencies and amplitudes of the N13 and P19 peaks of T-SSEP. Furthermore, additional groups of patients were investigated to identify changes in the parameters of T-SSEP that might correspond to different states of anaesthesia and artificial muscle activity. RESULTS We reproducibly recorded T-SSEP responses in 99 patients with a mean latency of 12.4 ms (SD=0.93) and amplitude of 5.7 μV (SD=4.7). Collateral investigations concerning changes of T-SSEP caused by neuromuscular blockade improved independence of T-SSEP recordings to muscle relaxation in contrast to facial and cervical muscle activity. CONCLUSIONS We demonstrated the reliability of recording stable intra-operative T-SSEP responses with standardised electrophysiological and anaesthesiological regimes. SIGNIFICANCE We provided evidence of the non-muscular origin of T-SSEPs recorded from the scalp.

Differences between state entropy and bispectral index during analysis of identical electroencephalogram signals: a comparison with two randomised anaesthetic techniques.

BACKGROUND It is claimed that bispectral index (BIS) and state entropy reflect an identical clinical spectrum, the hypnotic component of anaesthesia. So far, it is not known to what extent different devices display similar index values while processing identical electroencephalogram (EEG) signals. OBJECTIVE To compare BIS and state entropy during analysis of identical EEG data. Inspection of raw EEG input to detect potential causes of erroneous index calculation. DESIGN Offline re-analysis of EEG data from a randomised, single-centre controlled trial using the Entropy Module and an Aspect A-2000 monitor. SETTING Klinikum rechts der Isar, Technische Universität München, Munich. PATIENTS Forty adult patients undergoing elective surgery under general anaesthesia. INTERVENTIONS Blocked randomisation of 20 patients per anaesthetic group (sevoflurane/remifentanil or propofol/remifentanil). Isolated forearm technique for differentiation between consciousness and unconsciousness. MAIN OUTCOME MEASURES Prediction probability (PK) of state entropy to discriminate consciousness from unconsciousness. Correlation and agreement between state entropy and BIS from deep to light hypnosis. Analysis of raw EEG compared with index values that are in conflict with clinical examination, with frequency measures (frequency bands/Spectral Edge Frequency 95) and visual inspection for physiological EEG patterns (e.g. beta or delta arousal), pathophysiological features such as high-frequency signals (electromyogram/high-frequency EEG or eye fluttering/saccades), different types of electro-oculogram or epileptiform EEG and technical artefacts. RESULTS PK of state entropy was 0.80 and of BIS 0.84; correlation coefficient of state entropy with BIS 0.78. Nine percent BIS and 14% state entropy values disagreed with clinical examination. Highest incidence of disagreement occurred after state transitions, in particular for state entropy after loss of consciousness during sevoflurane anaesthesia. EEG sequences which led to false ‘conscious’ index values often showed high-frequency signals and eye blinks. High-frequency EEG/electromyogram signals were pooled because a separation into EEG and fast electro-oculogram, for example eye fluttering or saccades, on the basis of a single EEG channel may not be very reliable. These signals led to higher Spectral Edge Frequency 95 and ratio of relative beta and gamma band power than EEG signals, indicating adequate unconscious classification. The frequency of other artefacts that were assignable, for example technical artefacts, movement artefacts, was negligible and they were excluded from analysis. CONCLUSION High-frequency signals and eye blinks may account for index values that falsely indicate consciousness. Compared with BIS, state entropy showed more false classifications of the clinical state at transition between consciousness and unconsciousness.

Comparison of Aintree and Fastrach techniques for low-skill fibreoptic intubation in patients at risk of secondary cervical injury: a randomised controlled trial.

BACKGROUND We compared two methods of asleep fibreoptic intubation in patients at risk of secondary cervical injury: the Aintree Intubation Catheter via a classic laryngeal mask airway (cLMA) versus the Fastrach technique via the intubating laryngeal mask airway (iLMA). OBJECTIVE To test which system has the highest rate of successful intubations in the clinical setting. DESIGN A randomised controlled study. SETTING Single-centre, between 2007 and 2010. PATIENTS We randomly allocated 80 patients (30 women and 50 men) who underwent elective neurosurgery of the cervical spine to either group, placed in a neutral position and wearing a soft cervical collar. Entry criteria were ASA status 1 to 3, age 18 to 80 years and written informed consent. Exclusion criteria were patients with cervical instability, known or predicted difficult airway, BMI greater than 40 kg m−2and symptomatic gastro-oesophageal reflux. INTERVENTIONS Two anaesthetists who were experienced in both techniques performed all anaesthesia procedures within the study. There was a maximum of three attempts for performing each technique. MAIN OUTCOME MEASURES The primary outcome was the rate of successful fibreoptic intubation in a neutral position. We also investigated the timing sequence for both techniques, the Brimacombe and Berry Bronchoscopy Score, and differences in technical aspects. RESULTS All 40 patients in the Aintree group but only 31 patients in the Fastrach group were intubated successfully. Thus, fibreoptic intubation failed significantly less using the Aintree technique (P = 0.002). For secondary outcomes, the cLMA was faster (260 versus 289 s, P = 0.039) and easier (P = 0.036) to insert than the iLMA. The fibreoptic view of the glottis according to the Brimacombe and Berry Bronchoscopy Score was better (P = 0.016) and the tracheal tube was easier to insert (P = 0.010) in the Aintree group. CONCLUSION Fibreoptic intubation using the Aintree system was more successful than the Fastrach technique in our population of patients in a neutral position wearing a soft cervical collar. The differences in the time to successful intubation between the two groups are unlikely to be clinically relevant.

Reducing the Indication for Ventilatory Support in the Severely Burned Patient: Results of a New Protocol Approach at a Regional Burn Center.

Initial management of the severely injured routinely includes sedation and mechanical ventilatory support. However, nonjudiciously applied mechanical ventilatory support can itself lead to poorer patient outcomes. In an attempt to reduce this iatrogenic risk, a standardized, in-house, five-point protocol providing clinical guidance on the use and duration of ventilation was introduced and analyzed, and the impact on patient outcomes was assessed. In 2007, a protocol for early spontaneous breathing was introduced and established in clinical practice. This protocol included: 1) early extubation (⩽6 hours after admission) in the absence of absolute ventilatory indication; 2) avoidance of “routine intubation” in spontaneously breathing patients; 3) early postoperative extubation, including patients requiring multiple surgical interventions; 4) intensive chest and respiratory physiotherapy with routine application of expectorants; and 5) early active mobilization. A retrospective clinical study compared patients (group A) over a 2-year period admitted under the new protocol with a historical patient group (group B). Patients in group A (n = 38) had fewer ventilator days over the time-course of treatment (3 [1; 5.8] vs 18.5 days [0.5; 20.5]; P = .0001) with a lower rate of tracheostomies (15.8 vs 54%; P = .0003). Patients on ventilation at admission in group A had shorter ventilation periods after admission (4.75 [4; 22.25] vs 378 hours [8.5; 681.5]; P = .0003), and 66.7% of these patients were extubated within 6 hours of admission (vs 9.1% in group B). No patients fulfilling the inclusion criteria required re- or emergency intubation. In the first 5 days of treatment, significantly lower Sequential Organ Failure Assessment scores were recorded in group A. There was also a trend for lower mortality rates (0 [0%] vs 6 [14%]), sepsis rates (24 [63.2%] vs 37 [88.1%]), and cumulative fluid balance on days 3 and 7 in group A. In contrast, group A demonstrated an elevated rate of pneumonia (15 [39.5%] vs 8 [19%]). These trends, however, lacked statistical significance. Our five-point protocol was safe and easily translated into clinical practice. In the authors experience, this protocol significantly reduced the ventilatory period in severely injured. Furthermore, this study suggests that many injured may be over-treated with routine ventilation, which carries accompanying risks.

Regional citrate anticoagulation for continuous renal replacement therapy in severe burns-a retrospective analysis of a protocol-guided approach.

INTRODUCTION For critically ill patients, the use of regional citrate anticoagulation as part of continuous renal replacement therapy (CRRT) has become increasingly common in recent years. However, there are scarce data on the use of this technique in patients with burns. The aim of this study was to examine the effectiveness, feasibility and complications of regional citrate anticoagulation for CRRT in burn patients, as well as the effects on coagulation and the electrolyte and acid-base balance. METHODS This retrospective study included all patients who received renal replacement therapy with citrate anticoagulation to treat acute kidney injury (AKI) between January 1, 2004 and December 31, 2009 at the burn unit of St. Georg Hospital GmbH in Leipzig. RESULTS During the examination period, 18 patients were treated using CRRT with regional citrate anticoagulation (CVVHDF in the pre-dilution mode). The median patient age was 64 years (49.5; 71), with a median TBSA of 42.5% (33.25; 52.5) and a median ABSI score of 10 (9; 10). The CRRT was initiated on a median of 6 days (4; 8.75) after admission to the hospital and continued for a median duration of 7 days (5; 8). The median dialysis dose was 38.2mlkgBW(-1)h(-1) (31.8; 42.1). The median effective filter operation time was 67h (46; 72). No relevant disorders associated with acid-base balance, electrolytes or coagulation occurred, and there were no bleeding complications. CONCLUSION In terms of bleeding risk and electrolyte and acid-base balance, regional citrate anticoagulation may be considered to be an effective, safe and user-friendly procedure for patients with severe burns and AKI.