The Hemodynamic Effects of Different Pacing Modalities After Cardiopulmonary Bypass in Patients With Reduced Left Ventricular Function.

OBJECTIVES: Patients with decreased left ventricular function undergoing cardiac surgery have a greater chance of difficult weaning from cardiopulmonary bypass and a poorer clinical outcome. Directly after weaning, interventricular dyssynchrony, paradoxical septal motion, and even temporary bundle-branch block might be observed. In this study, the authors measured arterial dP/dtmax, mean arterial pressure (MAP), and cardiac index using transpulmonary thermodilution, pulse contour analysis, and femoral artery catheter and compared the effects between right ventricular (A-RV) and biventricular (A-BiV) pacing on these parameters. DESIGN: Prospective study. SETTING: Single-center study. PARTICIPANTS: The study comprised 17 patients with a normal or prolonged QRS duration and a left ventricular ejection fraction ≤35% who underwent coronary artery bypass grafting with or without valve replacement. INTERVENTIONS: Temporary pacing wires were placed on the right atrium and both ventricles. Different pacing modalities were used in a standardized order. MEASUREMENTS AND MAIN RESULTS: A-BiV pacing compared with A-RV pacing demonstrated higher arterial dP/dtmax values (846 ± 646 mmHg/s v 800 ± 587 mmHg/s, p = 0.023) and higher MAP values (77 ± 19 mmHg v 71 ± 18 mmHg, p = 0.036). CONCLUSION: In patients with preoperative decreased left ventricular function undergoing coronary artery bypass grafting, A-BiV pacing improve the arterial dP/dtmax and MAP in patients with both normal and prolonged QRS duration compared with standard A-RV pacing. In addition, arterial dP/dtmax and MAP can be used to evaluate the effect of intraoperative pacing. In contrast to previous studies using more invasive techniques, transpulmonary thermodilution is easy to apply in the perioperative clinical setting.

Intelligent dynamic clinical checklists improved checklist compliance in the intensive care unit.

BACKGROUND: Checklists can reduce medical errors. However, the effectiveness of checklists is hampered by lack of acceptance and compliance. Recently, a new type of checklist with dynamic properties has been created to provide more specific checklist items for each individual patient. Our purpose in this simulation-based study was to investigate a newly developed intelligent dynamic clinical checklist (DCC) for the intensive care unit (ICU) ward round. METHODS: Eligible clinicians were invited to participate as volunteers. Highest achievable scores were established for six typical ICU scenarios to determine which items must be checked. The participants compared the DCC with the local standard of care. The primary outcomes were the caregiver satisfaction score and the percentages of checked items overall and of critical items requiring a direct intervention. RESULTS: In total, 20 participants were included, who performed 116 scenarios. The median percentage of checked items was 100.0% with the DCC and 73.6% for the scenarios completed with local standard of care ( P <0.001). Critical items remained unchecked in 23.1% of the scenarios performed with local standard of care and 0.0% of the scenarios where the DCC was available ( P <0.001). The mean satisfaction score of the DCC was 4.13 out of 5. CONCLUSIONS: This simulation study indicates that an intelligent DCC significantly increases compliance with best practice by reducing the percentage of unchecked items during ICU ward rounds, while the user satisfaction rate remains high. Real-life clinical research is required to evaluate this new type of checklist further.

Improving needle tip identification during ultrasound-guided procedures in anaesthetic practice.

Ultrasound guidance is becoming standard practice for needle-based interventions in anaesthetic practice, such as vascular access and peripheral nerve blocks. However, difficulties in aligning the needle and the transducer can lead to incorrect identification of the needle tip, possibly damaging structures not visible on the ultrasound screen. Additional techniques specifically developed to aid alignment of needle and probe or identification of the needle tip are now available. In this scoping review, advantages and limitations of the following categories of those solutions are presented: needle guides; alterations to needle or needle tip; three- and four-dimensional ultrasound; magnetism, electromagnetic or GPS systems; optical tracking; augmented (virtual) reality; robotic assistance; and automated (computerised) needle detection. Most evidence originates from phantom studies, case reports and series, with few randomised clinical trials. Improved first-pass success and reduced performance time are the most frequently cited benefits, whereas the need for additional and often expensive hardware is the greatest limitation to widespread adoption. Novice ultrasound users seem to benefit most and great potential lies in education. Future research should focus on reporting relevant clinical parameters to learn which technique will benefit patients most in terms of success and safety.

Pulmonary blood volume measured by contrast enhanced ultrasound: a comparison with transpulmonary thermodilution.

BACKGROUND: Blood volume quantification is essential for haemodynamic evaluation guiding fluid management in anaesthesia and intensive care practice. Ultrasound contrast agent (UCA)-dilution measured by contrast enhanced ultrasound (CEUS) can provide the UCA mean transit time (MTT) between the right and left heart, enabling the assessment of the intrathoracic blood volume (ITBV(UCA)). The purpose of the present study was to investigate the agreement between UCA-dilution using CEUS and transpulmonary thermodilution (TPTD) in vitro and in vivo. METHODS: In an in vitro setup, with variable flows and volumes, we injected a double indicator, ice-cold saline with SonoVue(®), and performed volume measurements using transesophageal echo and thermodilution by PiCCO(®). In a pilot study, we assigned 17 patients undergoing elective cardiac surgery for pulmonary blood volume (PBV) measurement using TPTD by PiCCO(®) and ITBV by UCA-dilution. Correlation coefficients and Bland-Altman analysis were performed for all volume measurements. RESULTS: In vitro, 73 experimental MTT's were obtained using PiCCO(®) and UCA-dilution. The volumes by PiCCO(®) and UCA-dilution correlated with true volumes; r(s)=0.96 (95% CI, 0.93-0.97; P<0.0001) and r(s)=0.97 (95% CI, 0.95-0.98; P<0.0001), respectively. The bias of PBV by PiCCO(®) and ITBV(UCA) were -380 ml and -42 ml, respectively. In 16 patients, 86 measurements were performed. The correlation between PBV by PiCCO(®) and ITBV(UCA) was r(s)=0.69 (95% CI 0.55-0.79; P<0.0001). Bland-Altman analysis revealed a bias of -323 ml. CONCLUSIONS: ITBV assessment with CEUS seems a promising technique for blood volume measurement, which is minimally-invasive and bedside applicable. CLINICAL TRIAL REGISTRATION: ISRCTN90330260.

Phrenic nerve palsy following interscalene brachial plexus block; a long lasting serious complication.

Interscalene brachial plexus block (ISBPB) offers good analgesia for painful surgical procedures on the shoulder. We here describe two cases of long-term phrenic palsy following ISBPB that occurred in our practice in a relative short time period and both clearly illustrate the devastating impact of this complication for the patient. We will discuss the benefit of ISBPB in the context of the incidence and significant disability of hemi diaphragm paresis. Anesthesiologists must be aware of this complication and carefully weigh the advantages of ISPBP against the risks of this complication. When ISPBP is considered, the fact that the incidence of prolonged phrenic nerve palsy may be higher than previously expected should be taken into account carefully. A reevaluation on the indication and patient selection of ISBPB may even be warranted.

Effectiveness, safety and efficacy of INTELLiVENT-adaptive support ventilation, a closed-loop ventilation mode for use in ICU patients - a systematic review.

Introduction: INTELLiVENT-Adaptive Support Ventilation (INTELLiVENT-ASV), an advanced closed-loop ventilation mode for use in intensive care unit (ICU) patients, is equipped with algorithms that automatically adjust settings on the basis of physiologic signals and patient's activity. Here we describe its effectiveness, safety, and efficacy in various types of ICU patients.Areas covered: A systematic search conducted in MEDLINE, EMBASE, the Cochrane Central register of Controlled Trials (CENTRAL), and in Google Scholar identified 10 randomized clinical trials.Expert opinion: Studies suggest INTELLiVENT-ASV to be an effective automated mode with regard to the titrations of tidal volume, airway pressure, and oxygen. INTELLiVENT-ASV is as safe as conventional modes. However, thus far studies have not shown INTELLiVENT-ASV to be superior to conventional modes with regard to duration of ventilation and other patient-centered outcomes. Future studies are needed to test its efficacy.

Testing the effects of checklists on team behaviour during emergencies on general wards: An observational study using high-fidelity simulation.

INTRODUCTION: Clinical teams struggle on general wards with acute management of deteriorating patients. We hypothesized that the Crisis Checklist App, a mobile application containing checklists tailored to crisis-management, can improve teamwork and acute care management. METHODS: A before-and-after study was undertaken in high-fidelity simulation centres in the Netherlands, Denmark and United Kingdom. Clinical teams completed three scenarios with a deteriorating patient without checklists followed by three scenarios using the Crisis Checklist App. Teamwork performance as the primary outcome was assessed by the Mayo High Performance Teamwork scale. The secondary outcomes were the time required to complete all predefined safety-critical steps, percentage of omitted safety-critical steps, effects on other non-technical skills, and users' self-assessments. Linear mixed models and a non-parametric survival test were conducted to assess these outcomes. RESULTS: 32 teams completed 188 scenarios. The Mayo High Performance Teamwork scale mean scores improved to 23.4 out of 32 (95% CI: 22.4-24.3) with the Crisis Checklist App compared to 21.4 (20.4-22.3) with local standard of care. The mean difference was 1.97 (1.34-2.6; p < 0.001). Teams that used the checklists were able to complete all safety-critical steps of a scenario in more simulations (40/95 vs 21/93 scenarios) and these steps were completed faster (stratified log-rank test χ2 = 8.0; p = 0.005). The self-assessments of the observers and users showed favourable effects after checklist usage for other non-technical skills including situational awareness, decision making, task management and communication. CONCLUSIONS: Implementation of a novel mobile crisis checklist application among clinical teams was associated in a simulated general ward setting with improved teamwork performance, and a higher and faster completion rate of predetermined safety-critical steps.

Intra-thoracic blood volume measurement by contrast magnetic resonance imaging.

The intra-thoracic blood volume (ITBV) is a cardiovascular parameter related to the cardiac preload and left ventricular function. Its assessment is, therefore, important for diagnosis and follow-up of several cardiovascular dysfunctions. Nowadays, the ITBV can be accurately measured only by invasive indicator dilution techniques, which require a double catheterization of the patient. In this study, a novel technique is presented for ITBV assessment by dynamic magnetic resonance imaging after intravenous injection of a small bolus of gadolinium chelate. The dose was chosen on the basis of in vitro calibration. The bolus first pass is detected from a simultaneous dynamic image series of the right and left ventricles. Two indicator dilution curves are derived and used to inspect the transpulmonary dilution system. Various mathematical models for the interpretation of the measured indicator dilution curves are compared. The ITBV is assessed as the product of the transpulmonary mean transit time of the indicator and the cardiac output, obtained by phase contrast magnetic resonance angiography. In vitro measurements showed a correlation coefficient larger than 0.99 and preliminary tests with volunteers proved the feasibility of the method, opening new possibilities for noninvasive quantitative cardiovascular diagnostics.

Strategy for implementation and first results of advanced clinical decision support in hospital pharmacy practice.

Clinical decision support systems (CDSS) are the new generation clinical support tools that 'make it easy to do it right'. Despite promising results, these systems are not common practice, although experts agree that the necessary revolution in health care will depend on its implementation. To accelerate adoption a strategy is handed for structured development and validation of CDSS' content (clinical rules). The first results show that the proposed strategy is easily applicable for creating specific and reliable rules, generating relevant recommendations.

Differences in identification of patients' deterioration may hamper the success of clinical escalation protocols.

BACKGROUND: Timely and consistent recognition of a 'clinical crisis', a life threatening condition that demands immediate intervention, is essential to reduce 'failure to rescue' rates in general wards. AIM: To determine how different clinical caregivers define a 'clinical crisis' and how they respond to it. DESIGN: An international survey. METHODS: Clinicians working on general wards, intensive care units or emergency departments in the Netherlands, the United Kingdom and Denmark were asked to review ten scenarios based on common real-life cases. Then they were asked to grade the urgency and severity of the scenario, their degree of concern, their estimate for the risk for death and indicate their preferred action for escalation. The primary outcome was the scenarios with a National Early Warning Score (NEWS) ≥7 considered to be a 'clinical crisis'. Secondary outcomes included how often a rapid response system (RRS) was activated, and if this was influenced by the participant's professional role or experience. The data from all participants in all three countries was pooled for analysis. RESULTS: A total of 150 clinicians participated in the survey. The highest percentage of clinicians that considered one of the three scenarios with a NEWS ≥7 as a 'clinical crisis' was 52%, while a RRS was activated by <50% of participants. Professional roles and job experience only had a minor influence on the recognition of a 'clinical crisis' and how it should be responded to. CONCLUSION: This international survey indicates that clinicians differ on what they consider to be a 'clinical crisis' and on how it should be managed. Even in cases with a markedly abnormal physiology (i.e. NEWS ≥7) many clinicians do not consider immediate activation of a RRS is required.

On the physical and stochastic representation of an indicator dilution curve as a gamma variate.

The analysis of intravascular indicator dynamics is important for cardiovascular diagnostics as well as for the assessment of tissue perfusion, aimed at the detection of ischemic regions or cancer hypervascularization. To this end, indicator dilution curves are measured after the intravenous injection of an indicator bolus and fitted by parametric models for the estimation of the hemodynamic parameters of interest. Based on heuristic reasoning, the dilution process is often modeled by a gamma variate. In this paper, we provide both a physical and stochastic interpretation of the gamma variate model. The accuracy of the model is compared with the local density random walk model, a known model based on physics principles. Dilution curves were measured by contrast ultrasonography both in vitro and in vivo (20 patients). Blood volume measurements were used to test the accuracy and clinical relevance of the estimated parameters. Both models provided accurate curve fits and volume estimates. In conclusion, the proposed interpretations of the gamma variate model describe physics aspects of the dilution process and lead to a better understanding of the observed parameters, increasing the value and credibility of the model, and possibly expanding its diagnostic applications.

Current practice of closed-loop mechanical ventilation modes on intensive care units - a nationwide survey in the Netherlands.

BACKGROUND: The most recent modes for mechanical ventilation are closed-loop modes, which are able to automatically adjust certain respiratory settings. Although closed-loop modes have been investigated in various clinical trials, it is unclear to what extent these modes are actually used in clinical practice. The aim of this study was to determine closed-loop ventilation practice on intensive care units (ICUs) in the Netherlands, and to explore reasons for not applying closed-loop ventilation. Our hypothesis was that closed-loop ventilation is increasingly used. METHODS: A short survey was conducted among all non-paediatric ICUs in the Netherlands. Use of closed-loop modes was classified as frequently, occasionally or never, if respondents stated they had used these modes in the last week, in the last month/year, or never, respectively. RESULTS: The response rate of the survey was 82% (72 of 88). Respondents had access to a closed-loop ventilation mode in 58% of the ICUs (42 of 72). Of these ICUs, 43% (18 of 42) frequently applied a closed-loop ventilation mode, while 57% (24 of 42) never or occasionally used it. Reasons for not using these modes were lack of knowledge (40%), insufficient evidence reporting a beneficial effect (35%) and lack of confidence (25%). CONCLUSION: This study does not support our hypothesis that closed-loop ventilation is increasingly used in the Dutch ICU setting. While industry continues to develop new closed-loop modes, implementation of these modes in clinical practice seems to encounter difficulties. Various barriers could play a role, and these all need attention in future investigations.

Inability to ventilate after tube exchange postoperative to pneumonectomy.

We report a case of inability to ventilate a patient after completion of pneumonectomy, due to migrated tumor tissue to the contralateral side. This represents an unusual complication with a high mortality rate. We have managed to find the cause in time and were able to remove the obstructive tissue using bronchoscopy.

Three-dimensional quantification of regional left-ventricular dyssynchrony by magnetic resonance imaging.

Heart failure accounts for over five million patients in the United States alone. Many of them present dyssynchronous left ventricular (LV) contraction, whose treatment by cardiac resynchronization therapy (CRT) is until now guided by electrocardiographic analysis. One third of the selected patients, however, does not respond to the therapy. Aiming at improving the response rate, recent studies showed the importance of left bundle branch block (LBBB) configurations. Therefore, in order to detect motion patterns that relate to LBBB, this paper presents a novel method for three-dimensional quantification of regional LV mechanical dyssynchrony. LV wall-motion analysis is performed on magnetic resonance imaging (MRI) cines segmented by commercial software. Mutual delays between endocardial wall motion in different LV regions are estimated by cross correlation followed by phase difference analysis in frequency domain, achieving unlimited time resolution. Rather than focusing on the systolic phase, the full cardiac cycle is used to estimate the contraction timing. The method was successfully validated against MRI tagging in five dogs before and after LBBB induction. Preliminary validation in humans with 10 LBBB patients and 7 healthy subjects showed the method feasibility and reproducibility, with sensitivity and specificity in LBBB detection equal to 95.1% and 99.4%, respectively.

Assessment of ventricular mechanical dyssynchrony by short-axis MRI.

Nowadays, patients with symptomatic heart failure and intraventricular conduction delay can be treated with a cardiac resynchronization therapy. Electrical dyssynchrony is typically adopted to represent myocardial dyssynchrony, to be compensated by cardiac resynchronization therapy. One third of the patients, however, does not respond to the therapy. Therefore, imaging modalities aimed at the mechanical dyssynchrony estimation have been recently proposed to improve patient selection criteria. This paper presents a novel fully-automated method for regional mechanical left-ventricular dyssynchrony quantification in short-axis magnetic resonance imaging. The endocardial movement is described by time-displacement curves with respect to an automatically-determined reference point. These curves are analyzed for the estimation of the regional contraction timings. Four methods are proposed and tested for the contraction timing estimation. They were evaluated in two groups of subjects with and without left bundle branch block. The standard deviation of the contraction timings showed a significant increase for left bundle branch block patients with all the methods. However, a novel method based on phase spectrum analysis shows a better specificity and sensitivity. This method may therefore provide a valuable prognostic indicator for heart failure patients with dyssynchronous ventricular contraction, adding new possibilities for regional timing analysis.

Laparoscopic cholecystectomy under segmental thoracic spinal anaesthesia: a feasibility study.

BACKGROUND: Laparoscopic surgery is normally performed under general anaesthesia, but regional techniques have been found beneficial, usually in the management of patients with major medical problems. Encouraged by such experience, we performed a feasibility study of segmental spinal anaesthesia in healthy patients. METHODS: Twenty ASA I or II patients undergoing elective laparoscopic cholecystectomy received a segmental (T10 injection) spinal anaesthetic using 1 ml of bupivacaine 5 mg ml-1 mixed with 0.5 ml of sufentanil 5 microg ml-1. Other drugs were only given (systemically) to manage patient anxiety, pain, nausea, hypotension, or pruritus during or after surgery. The patients were reviewed 3 days postoperatively by telephone. RESULTS: The spinal anaesthetic was performed easily in all patients, although one complained of paraesthesiae which responded to slight needle withdrawal. The block was effective for surgery in all 20 patients, six experiencing some discomfort which was readily treated with small doses of fentanyl, but none requiring conversion to general anaesthesia. Two patients required midazolam for anxiety and two ephedrine for hypotension. Recovery was uneventful and without sequelae, only three patients (all for surgical reasons) not being discharged home on the day of operation. CONCLUSIONS: This preliminary study has shown that segmental spinal anaesthesia can be used successfully and effectively for laparoscopic surgery in healthy patients. However, the use of an anaesthetic technique involving needle insertion into the vertebral canal above the level of termination of the spinal cord requires great caution and should be restricted in application until much larger numbers of patients have been studied.

Contrast ultrasound methods for left-ventricle ejection fraction measurements.

The left-ventricle ejection fraction is an important cardiac-efficiency measure that is regularly used in cardiology. Standard estimations are based on time-consuming geometrical analysis and modelling, which requires experienced cardiologists. Alternative methods are very invasive due to the need for cardiac catheterization. In this paper we present and study a minimally-invasive indicator dilution technique for ejection fraction quantification that has recently been developed. It is based on a peripheral injection of an ultrasound contrast agent bolus. Left-atrium and left-ventricle acoustic intensities are recorded versus time by transthoracic echocardiography during contrast bolus passage. The measured curves are corrected for attenuation distortion, filtered to suppress the measurement noise, and processed by an adaptive Wiener deconvolution algorithm for the estimation of the left-ventricle impulse response. The estimated impulse response is interpolated by a mono-compartment exponential model for the ejection fraction assessment. An adaptive search of the interval for the model fitting is also included. The feasibility of the method is tested on 52 measurements in patients with left-ventricle ejection fractions between 10% and 80%. The results are promising and show a 0.83 correlation coefficient with echographic biplane ejection fraction measurements.