Robert Schier

The Impact of Trendelenburg Position and Positive End-Expiratory Pressure on the Internal Jugular Cross-Sectional Area

BACKGROUND: Increasing the cross-sectional area (CSA) of the right internal jugular vein facilitates cannulation and decreases complications. Maneuvers such as the Trendelenburg tilt position and ventilation with a positive end-expiratory pressure (PEEP) may increase the CSA of the right internal jugular vein. We determined the changes in the CSA in response to different maneuvers. METHODS: The CSA (cm2) of the right internal jugular vein was assessed in 50 anesthetized adult cardiothoracic surgery patients using 2-dimensional ultrasound. First, the CSA was measured in response to supine position with no PEEP (control condition, S0) and compared with 5 different randomly ordered maneuvers: (1) PEEP ventilation with 5 cm H2O (S5), (2) PEEP with 10 cm H2O (S10), (3) a 20° Trendelenburg tilt position with a PEEP of 0 cm H2O (T0), (4) a 20° Trendelenburg tilt position combined with a PEEP of 5 cm H2O (T5), and (5) a 20° Trendelenburg tilt position combined with a PEEP of 10 cm H2O (T10). RESULTS: All maneuvers increased the CSA of the right internal jugular vein with respect to the control condition S0 (all P < 0.05). S5 increased the CSA on average by 15.9%, S10 by 22.3%, T0 by 39.4%, T5 by 38.7%, and T10 by 49.7%. CONCLUSION: In a comparison of the effectiveness of applying different PEEP levels and/or the Trendelenburg tilt position on the CSA of the right internal jugular vein, the Trendelenburg tilt position was most effective.

Epidural space identification: A meta-analysis of complications after air versus liquid as the medium for loss of resistance

BACKGROUND: The best method for identifying the epidural space for neuraxial blocks is controversial. We conducted this meta-analysis to test the hypothesis that loss of resistance with liquid reduces complications with epidural placement. METHODS: The MEDLINE, EMBASE, and Cochrane databases were searched for prospective, randomized studies comparing air versus liquid as the medium for loss of resistance during epidural space identification in adults. Data were abstracted from 5 studies (4 obstetric and 1 nonobstetric) (n = 4422 patients) that met inclusion criteria and analyzed for the following 6 outcomes: difficult catheter insertion, paresthesia, intravascular catheter insertion, accidental dural puncture, postdural puncture headache, and partial block. RESULTS: The overall risk differences for adverse outcome between the different mediums were not statistically different for the obstetric population. A small, but statistically significant, risk difference for postdural puncture headache was observed when fluid was used during epidural placement for chronic pain management. CONCLUSION: Larger studies that overcome limitations of heterogeneity across studies and a relatively infrequent occurrence of complications are required to determine the optimal medium for loss of resistance during epidural block.

Tumor Endothelial Markers Define Novel Subsets of Cancer-Specific Circulating Endothelial Cells Associated with Antitumor Efficacy

Circulating endothelial cells (CEC) are derived from multiple sources, including bone marrow (circulating endothelial progenitors; CEP), and established vasculature (mature CEC). Although CECs have shown promise as a biomarker for patients with cancer, their utility has been limited, in part, by the lack of specificity for tumor vasculature and the different nonmalignant causes that can impact CEC. Tumor endothelial markers (TEM) are antigens enriched in tumor versus nonmalignant endothelia. We hypothesized that TEMs may be detectable on CEC and that these circulating TEM(+) endothelial cells (CTEC) may be a more specific marker for cancer and tumor response than standard CEC. We found that tumor-bearing mice had a relative increase in numbers of circulating CTEC, specifically with increased levels of TEM7 and TEM8 expression. Following treatment with various vascular-targeting agents, we observed a decrease in CTEC that correlated with the reductions in tumor growth. We extended these findings to human clinical samples and observed that CTECs were present in patients with esophageal cancer and non-small cell lung cancer (N = 40), and their levels decreased after surgical resection. These results demonstrate that CTECs are detectable in preclinical cancer models and patients with cancer. Furthermore, they suggest that CTECs offer a novel cancer-associated marker that may be useful as a blood-based surrogate for assessing the presence of tumor vasculature and antiangiogenic drug activity.

Preoperative Microvascular Dysfunction: A Prospective, Observational Study Expanding Risk Assessment Strategies in Major Thoracic Surgery

BACKGROUNDnBrachial artery reactivity testing (BART)--a surrogate test of microvascular function--predicts cardiac risk in the nonsurgical population and associates it with adverse outcome after vascular surgery. This pilot study investigated BART-derived variables, including flow-mediated dilation (FMD), in preoperative risk stratification for major thoracic surgery.nnnMETHODSnAfter institutional review board approval, BART was performed in 63 patients before major thoracic surgery. Ultrasonography recorded two-dimensional images and Doppler flow signals of the brachial artery preoperatively at baseline and after induced reactive hyperemia. Variables derived using BART were correlated with preoperative risk factors, established risk scores, and postoperative complications.nnnRESULTSnThe median preoperative FMD value in patients without postoperative complications was 11.5%. This value was used to delineate all patients into two groups: low (FMD < 11.5%) and high (FMD ≥ 11.5%) FMD cohorts. Patients in the low FMD group experienced more postoperative complications: 54% versus 30% had one or more adverse postoperative event, and 11% versus 0% had three or more adverse postoperative events (p < 0.001), respectively. The low FMD group required longer intensive care unit (3.9 ± 2.0 days versus 0.9 ± 0.3 days; p = 0.015) and hospital (14.0 ± 3.3 days versus 6.8 ± 0.6 days; p = 0.007) stays. This cutoff point for FMD accurately predicted 71% of the patients with adverse postoperative events, achieving 71.4% (95% confidence interval, 54.7 to 88.2) sensitivity and 48.6% (95% confidence interval, 32.0 to 65.1) specificity.nnnCONCLUSIONSnUsing BART, preoperative microvascular dysfunction can be identified in patients at increased risk for postoperative complications. These data suggest that larger observational studies and studies exploring preoperative optimization strategies aimed at improving microvascular function are warranted.

In a difficult access scenario, supraglottic airway devices improve success and time to ventilation.

The success of tracheal intubation (TI) is unacceptably low in unconventional positions. Supraglottic airway devices (SAD) have become an important alternative. An airway manikin was placed in a car, simulating an entrapped motor vehicle accident victim. The rescuer only had access through the driver’s door. Participants were (n=25) anaesthesiologists with experience in prehospital emergency medicine. They attempted to secure the airway by TI or an SAD (Ambu AuraOnce, iGel, laryngeal tube) in a random sequence. Performance was compared using the Wilcoxon signed-rank test. P values less than 0.05 were considered statistically significant. Fastest effective ventilation was achieved with iGel (11.5±6.9u2009s, P<0.001), followed by a laryngeal mask (15.1±5.6u2009s, P<0.001) and a laryngeal tube (17.6±5.3u2009s, P<0.001); TI was the slowest (42.8±23.9u2009s, comparator). iGel (P<0.001) and laryngeal mask (P=0.01) also significantly outperformed the laryngeal tube. First ventilation was achieved significantly faster with SADs compared with TI. Success rates were also higher when using SADs.

Endothelial progenitor cell mobilization by preoperative exercise: a bone marrow response associated with postoperative outcome

BACKGROUNDnPreoperative anaemia is associated with increased morbidity in patients undergoing major surgery. Whether erythrocytes are the only bone-marrow-derived cell lineage that associates with increased surgical complications is unknown. This prospective observational trial studied the mobilization of endothelial progenitor cells (EPCs) in response to exercise in association with postoperative complications.nnnMETHODSnAfter IRB approval, 60 subjects undergoing major thoracic surgery were exercised to exhaustion (peak V̇(O₂)). Peripheral blood collected before and after peak exercise was quantified for EPC lineages by fluorescence-activated cell sorter analysis. Complication analysis was based on the Clavien-Dindo classification.nnnRESULTSnExhaustive exercise increased EPC [CD45-133+34+ cells=150 (0.00-5230) to 220 (0.00-1270) cells μl(-1); median change (range)=20 (-4,180-860) cells μl(-1); P=0.03] but not mature endothelial cell (EC) subpopulations. Pre-exercise levels [odds ratio (OR)=0.86, 95% confidence interval (CI): 0.37-2.00, P=0.72), change after exercise as a continuous variable (OR=0.95, 95% CI: 0.41-2.22, P=0.91) and a positive response after exercise (change >0 cells μl(-1); OR=0.41, 95% CI: 0.13-1.28, P=0.12) were not statistically significantly associated with the incidence of postoperative complications. Post-hoc receiver operating characteristic curve analyses revealed that subjects with a CD45-133+34+ increase ≥60 cells μl(-1) in response to exercise suffered fewer postoperative complications [86% sensitivity, 48% specificity and AUC=0.67 (95% CI: 0.52-0.81)].nnnCONCLUSIONSnPreoperative exercise induces EPC into the peripheral circulation. Subjects with a poor EPC response had a pre-existing propensity for postoperative complications. This warrants further research into the role of bone marrow function as a critical component to endothelial repair mechanisms.nnnCLINICAL TRIAL REGISTRATIONnIRB 2003-0434 (University of Texas M.D. Anderson Cancer Center, Houston, TX, USA).

Tracheal intubation in the ice-pick position with video laryngoscopes: A randomised controlled trial in a manikin

CONTEXT Tracheal intubation in nonstandardised positions is associated with a higher risk of tube misplacement and may have deleterious consequences for patients. Video laryngoscopes for tracheal intubation facilitate both glottic view and success rates. However, their use in the ice-pick position has not been evaluated. OBJECTIVE To evaluate the role of video laryngoscopes for tracheal intubation in the ice-pick position. DESIGN A randomised, controlled manikin trial. SETTING A standardised airway manikin was placed in the corner of a room. Tracheal intubation was only possible from the lower right side of the manikin. In randomised order, participants used a standard Macintosh laryngoscope and GlideScope Ranger, Storz C-MAC, Pentax AWS, Airtraq and McGrath Series5 video laryngoscopes. Statistical analysis was performed using the Wilcoxon signed-rank and McNemars tests; A P value of less than 0.05 was deemed statistically significant. PARTICIPANTS Twenty anaesthesiologists, all emergency medicine board-certified. MAIN OUTCOME MEASURES Time to first ventilation (primary); time to glottic view and confirmation of tube position (secondary). RESULTS Successful ventilation was achieved most rapidly with the Macintosh laryngoscope (36.1u200a±u200a13.4u200as; reference method), followed by the Airtraq (38.4u200a±u200a36.3u200as; Pu200a=u200an.s.), Pentax AWS (51.6u200a±u200a43.3u200as; Pu200a=u200an.s.) and Storz C-Mac (62.7u200a±u200a49.7u200as; Pu200a=u200an.s.). The use of the GlideScope Ranger (79.8u200a±u200a61.9u200as, Pu200a=u200a0.01) and McGrath series5 (79.8u200a±u200a58.5u200as, Pu200a=u200a0.023) resulted in significantly longer times. When comparing overall intubation success, the rate of successful tracheal intubation was higher with the Airtraq than with the McGrath Series5 (Pu200a=u200a0.031; all others n.s.). CONCLUSION The use of video laryngoscopes did not result in higher success rates or faster tracheal intubation in the ice-pick position when compared with conventional laryngoscopy in this manikin study. TRIAL REGISTRATION www.clinicaltrials.gov, NCT01210105.

Endothelial dysfunction in the perioperative setting.

Although perioperative macrovascular events (eg, myocardial infarction, stroke) are readily evident, their absolute incidence remains relatively low. In contrast, microvascular dysfunction and its role in perioperative morbidity is not easily measured. Microvascular dysfunction is likely to have a greater impact on noncardiovascular complications (eg, wound healing and end-organ failure), through impaired perfusion, than that which is readily appreciated. Inflammation and oxidative stress, such as that induced by surgical trauma, disrupts endothelial homeostasis thereby decreasing the bioavailability of nitric oxide. This predisposes blood vessels to vasoconstriction, inflammation, leukocyte adhesion, thrombosis—factors that contribute to perioperative cardiovascular events at both macrovascular and microvascular level. Current clinical strategies applicable to the perioperative setting that improve microvascular health include preoperative exercise therapy, pharmacologic interventions (eg, statins, newer β-blockers) and attempts to stimulate mobilization and homing of bone marrow—derived endothelial progenitor cells. Many of these strategies are still in their infancy and large prospective trials that investigate the impact of these therapeutic options on postoperative outcome are eagerly awaited.

Transcutaneous PtcCO2 measurement in combination with arterial blood gas analysis provides superior accuracy and reliability in ICU patients

Hyper or hypoventilation may have serious clinical consequences in critically ill patients and should be generally avoided, especially in neurosurgical patients. Therefore, monitoring of carbon dioxide partial pressure by intermittent arterial blood gas analysis (PaCO2) has become standard in intensive care units (ICUs). However, several additional methods are available to determine PCO2 including end-tidal (PetCO2) and transcutaneous (PtcCO2) measurements. The aim of this study was to compare the accuracy and reliability of different methods to determine PCO2 in mechanically ventilated patients on ICU. After approval of the local ethics committee PCO2 was determined in nxa0=xa032 ICU consecutive patients requiring mechanical ventilation: (1) arterial PaCO2 blood gas analysis with Radiometer ABL 625 (ABL; gold standard), (2) arterial PaCO2 analysis with Immediate Response Mobile Analyzer (IRMA), (3) end-tidal PetCO2 by a Propaq 106 EL monitor and (4) transcutaneous PtcCO2 determination by a Tina TCM4. Bland–Altman method was used for statistical analysis; pxa0<xa00.05 was considered statistically significant. Statistical analysis revealed good correlation between PaCO2 by IRMA and ABL (R2xa0=xa00.766; pxa0<xa00.01) as well as between PtcCO2 and ABL (R2xa0=xa00.619; pxa0<xa00.01), whereas correlation between PetCO2 and ABL was weaker (R2xa0=xa00.405; pxa0<xa00.01). Bland–Altman analysis revealed a bias and precision of 2.0xa0±xa03.7xa0mmHg for the IRMA, 2.2xa0±xa05.7xa0mmHg for transcutaneous, and −5.5xa0±xa05.6xa0mmHg for end-tidal measurement. Arterial CO2 partial pressure by IRMA (PaCO2) and PtcCO2 provided greater accuracy compared to the reference measurement (ABL) than the end-tidal CO2 measurements in critically ill in mechanically ventilated patients patients.

Dispatcher-assisted compression-only cardiopulmonary resuscitation provides best quality cardiopulmonary resuscitation by laypersons: A randomised controlled single-blinded manikin trial.

BACKGROUND High-quality cardiopulmonary resuscitation (CPR) by laypersons is a key determinant of both outcome and survival for out-of-hospital cardiac arrest. Dispatcher-assisted CPR (telephone-CPR, T-CPR) increases the frequency and correctness of bystander-CPR but results in prolonged time to first chest compressions. However, it remains unclear whether instructions for rescue ventilation and/or chest compressions should be recommended for dispatcher-assisted CPR. OBJECTIVE The aim of this study was to evaluate both principles of T-CPR with respect to CPR quality. DESIGN Randomised controlled single-blinded manikin trial. SETTING University Hospital of Cologne, Germany, 1 July 2012 to 30 September 2012. PARTICIPANTS Sixty laypersons between 18 and 65 years. Medically educated individuals, medical professionals and pregnant women were excluded. Participants were asked to resuscitate a manikin and were randomised into three groups: not dispatcher-assisted (uninstructed) CPR (group 1; U-CPR; nu200a=u200a20), dispatcher-assisted compression-only CPR (group 2; DACO-CPR; nu200a=u200a19) and full dispatcher-assisted CPR with rescue ventilation (group 3; DAF-CPR; nu200a=u200a19). MAIN OUTCOME MEASURES Specific parameters of CPR quality [i.e. no-flow-time (NFT) as well as compression and ventilation parameters] were analysed. To compare different groups we used Students t test and P less than 0.05 was considered significant. RESULTS Initial NFT was lowest in the DACO-CPR group (mean 21.3u200a±u200a14.4%), followed by dispatcher-assisted full CPR (mean 49.1u200a±u200a8.5%) and by unassisted CPR (mean 55.0u200a±u200a12.9%). Initial NFT covering the time of instruction was lower in DACO-CPR (12.1u200a±u200a5.4%) as compared to dispatcher-assisted full CPR (20.7u200a±u200a8.1%). Compression depth was similar in all three groups: 40.6u200a±u200a13.0u200amm (unassisted CPR), 41.0u200a±u200a12.2u200amm (DACO-CPR) and 38.8u200a±u200a15.8u200amm (dispatcher-assisted full CPR). Average compression frequency was highest in the DACO-CPR group (65.2u200a±u200a22.4u200amin−1) compared with the unassisted CPR group (35.6u200a±u200a24.2u200amin−1) and the dispatcher-assisted full CPR group (44.5u200a±u200a10.8u200amin−1). Correct rescue ventilation was given in 3.1u200a±u200a11.1% (unassisted CPR) and 1.6u200a±u200a16.1% (dispatcher-assisted full CPR) of all ventilation attempts. CONCLUSION Best quality of CPR was achieved by DACO-CPR because of superior compression frequencies and reduced NFT. In contrast, the full dispatcher-assisted CPR with a longer initial instructing phase (initial NFT) did not result in enhanced CPR quality or an optimised compression depth.