Paul Elbers

Ten good reasons to practice ultrasound in critical care

Over the past decade, critical care ultrasound has gained its place in the armamentarium of monitoring tools. A greater understanding of lung, abdominal, and vascular ultrasound plus easier access to portable machines have revolutionised the bedside assessment of our ICU patients. Because ultrasound is not only a diagnostic test, but can also be seen as a component of the physical exam, it has the potential to become the stethoscope of the 21st century. Critical care ultrasound is a combination of simple protocols, with lung ultrasound being a basic application, allowing assessment of urgent diagnoses in combination with therapeutic decisions. The LUCI (Lung Ultrasound in the Critically Ill) consists of the identification of ten signs: the bat sign (pleural line); lung sliding (seashore sign); the A-lines (horizontal artefact); the quad sign and sinusoid sign indicating pleural effusion; the fractal and tissue-like sign indicating lung consolidation; the B-lines and lung rockets indicating interstitial syndromes; abolished lung sliding with the stratosphere sign suggesting pneumothorax; and the lung point indicating pneumothorax. Two more signs, the lung pulse and the dynamic air bronchogram, are used to distinguish atelectasis from pneumonia. The BLUE protocol (Bedside Lung Ultrasound in Emergency) is a fast protocol (< 3 minutes), also including a vascular (venous) analysis allowing differential diagnosis in patients with acute respiratory failure. With this protocol, it becomes possible to differentiate between pulmonary oedema, pulmonary embolism, pneumonia, chronic obstructive pulmonary disease, asthma, and pneumothorax, each showing specific ultrasound patterns and profiles. The FALLS protocol (Fluid Administration Limited by Lung Sonography) adapts the BLUE protocol to be used in patients with acute circulatory failure. It makes a sequential search for obstructive, cardiogenic, hypovolemic, and distributive shock using simple real-time echocardiography in combination with lung ultrasound, with the appearance of B-lines considered to be the endpoint for fluid therapy. An advantage of lung ultrasound is that the patient is not exposed to radiation, and so the LUCI-FLR project (LUCI favouring limitation of radiation) can be unfolded in trauma patients. Although it has been practiced for 25 years, critical care ultrasound is a relatively young but expanding discipline and can be seen as the stethoscope of the modern intensivist. In this review, the usefulness and advantages of ultrasound in the critical care setting are discussed in ten points. The emphasis is on a holistic approach, with a central role for lung ultrasound.

Speech in an Orally Intubated Patient

The authors show how an electrolarynx allowed a patient ventilated through an orotracheal tube to communicate with speech. A video is available at NEJM.org.

Right dose, right now: using big data to optimize antibiotic dosing in the critically ill

Antibiotics save lives and are essential for the practice of intensive care medicine. Adequate antibiotic treatment is closely related to outcome. However this is challenging in the critically ill, as their pharmacokinetic profile is markedly altered. Therefore, it is surprising that critical care physicians continue to rely on standard dosing regimens for every patient, regardless of the actual clinical situation. This review outlines the pharmacokinetic and pharmacodynamic principles that underlie the need for individualized and personalized drug dosing. At present, therapeutic drug monitoring may be of help, but has major disadvantages, remains unavailable for most antibiotics and has produced mixed results. We therefore propose the AutoKinetics concept, taking decision support for antibiotic dosing back to the bedside. By direct interaction with electronic patient records, this opens the way for the use of big data for providing the right dose at the right time in each patient.

Making Sense of Early High-dose Intravenous Vitamin C in Ischemia/Reperfusion Injury

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2018. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2018. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Executive summary on the use of ultrasound in the critically ill: consensus report from the 3rd Course on Acute Care Ultrasound (CACU)

Over the past decades, ultrasound (US) has gained its place in the armamentarium of monitoring tools in the intensive care unit (ICU). Critical care ultrasonography (CCUS) is the combination of general CCUS (lung and pleural, abdominal, vascular) and CC echocardiography, allowing prompt assessment and diagnosis in combination with vascular access and therapeutic intervention. This review summarises the findings, challenges lessons from the 3rd Course on Acute Care Ultrasound (CACU) held in November 2015, Antwerp, Belgium. It covers the different modalities of CCUS; touching on the various aspects of training, clinical benefits and potential benefits. Despite the benefits of CCUS, numerous challenges remain, including the delivery of CCUS training to future intensivists. Some of these are discussed along with potential solutions from a number of national European professional societies. There is a need for an international agreed consensus on what modalities are necessary and how best to deliver training in CCUS.

Fluid therapy in critically ill patients: perspectives from the right heart.

As right heart function can affect outcome in the critically ill patient, a thorough understanding of factors determining right heart performance in health and disease is pivotal for the critical care physician. This review focuses on fluid therapy, which remains controversial in the setting of impending or overt right heart failure. In this context, we will attempt to elucidate which patients are likely to benefit from fluid administration and for which patients fluid therapy would likely be harmful. Following a general discussion of right heart function and failure, we specifically focus on important causes of right heart failure in the critically ill, i.e. sepsis induced myocardial dysfunction, the acute respiratory distress syndrome, acute pulmonary embolism and the effects of positive pressure ventilation. It is argued that fluid therapy should always be cautiously administered with the right heart in mind, which calls for close multimodal monitoring.

Laboratory Tests: Blood Gases, Anion Gap, and Strong Ion Gap

Abstract Blood gas measurements provide the intensivist with diagnostic information on many organ systems. The anion gap (AG) and the strong ion gap (SIG) exploit the principle of electroneutrality to quantify the net balance of unmeasured ions in plasma. The AG should be corrected for abnormalities in plasma albumin and phosphate concentrations. The AG and SIG can be used to narrow the differential diagnosis of acid-base disorders, and an increased corrected AG or SIG is diagnostic of a metabolic acidosis (i.e., an acidifying process) irrespective of plasma pH or bicarbonate. The SIG is often perceived as more complex but frequently yields more precise results in critically ill patients. In addition, the strong ion model can be used to guide fluid management because it acknowledges that electrolyte changes are causal mechanisms of acid-base disorders.

Lung point in the absence of pneumothorax

Given a reported 100% specificity for the diagnosis of pneumothorax, the lung point has been considered a sign that cannot be mimicked. However, we now present a unique case of the presence of lung point in the absence of pneumothorax in a 75-year-old man admitted after coronary artery bypass graft (Fig. 1). Scanning at the right anterior third intercostal space showed absence of lung sliding (online video A), A-line and stratosphere sign indicating an A′-profile. Thus, a lung point was actively searched for and indeed found. Pneumothorax was ruled out by the presence of a B-line in the same view as the lung point (online video B), a post-operative chest X-ray and CT scan which indicated the pre-existence of asbestos-related pleural disease (Fig. 1a, c, d). We postulate that the healthy part of the lung moves unrestrictedly whereas the affected part is restricted, their transition resulting in a lung point. Another situation where lung point may be false positive is a ‘bleb’ point in bullous lung disease.

Compliance and statistics

Comments from Drs. Elbers and Heunks The VENTILA group recently found that severe hypercapnia is associated with increased risk of ICU mortality in acute respiratory distress syndrome (ARDS) [1]. This finding persisted even after correcting for various possible confounders using both multivariable logistic regression and propensity score analysis. This finding of possible harm of sustained hypercapnia in this setting is intriguing and provoking as hypercapnia has mostly been considered a relatively innocent bystander. Therefore, the authors should be commended, especially as they included data from as many as 1899 patients in 40 countries. While the advanced statistical methods used may sometimes be difficult to understand for many intensivists, they will surely recognize the association of hypercapnia with mortality as the level of hypercapnia is predictably related to the severity of ARDS, especially if pressureand volume-limiting strategies are used. Thus, before conclusions are to be drawn that may lead to premature changes in research agendas, allocation of funding, or clinical practice, we need to be reasonably certain that all relevant confounders have indeed been adequately considered. Do the authors agree that it would have been appropriate to have considered lung or respiratory system compliance or radiographic severity as possible confounders? While the latter may not be readily available, the former should be relatively straightforward to consider: minute ventilation divided by respiratory frequency divided by driving pressure—all of which seem to be available from the datasets—should at least be a surrogate of compliance. Are the authors willing to provide this analysis?

Focus on focus: lack of coherence between systemic and microvascular indices of oedema formation

BACKGROUND Fluid therapy remains a cornerstone of therapy in shock states. However, fluid overloading ultimately results in oedema formation which is related to excess morbidity and mortality. Handheld microscopes are now frequently used to study the sublingual microcirculation. As a corollary, these devices measure focal distance, or surface to capillary distance. Physiologically, this could represent a microvascular index of oedema formation and could have the potential to guide fluid therapy. This potential tool should be investigated, especially given the frequently reported lack of coherence between systemic and microvascular parameters in the critically ill. Therefore, we set out to assess the correlation between microvascular focal distance and systemic indices of oedema formation, specifically fluid balance and weight gain. METHODS Following ex vivo testing of focal distance measurement reliability, we conducted a prospective observational cohort study in patients admitted to the intensive care unit of our university teaching hospital. We determined surface to capillary distance using sidestream dark field (SDF) and incident dark field (IDF) imaging by assessing the focal distance point or object distance range at which a sharp recording could be made. Measurements were performed in post-cardiac surgery patients and in patients following emergency admission at two time points separated by at least several hours. Data on fluid balance, weight and weight gain were collected simultaneously. RESULTS Sixty patients were included. The focal setting, focus point for SDF and the object distance range for IDF did not differ significantly between time points. Focus was not correlated with difference in fluid balance or weight gain. CONCLUSIONS There is a lack of coherence between surface to capillary distance as determined by SDF or IDF imaging and fluid balance or weight gain. Thus, focal distance as a microvascular index of oedema formation cannot currently be used as a proxy for systemic indices of oedema formation. However, given the lack of coherence, further research should determine whether focal distance may provide better guidance for fluid therapy than traditional markers of overzealous fluid administration. RESULTS Sixty patients were included. Focal setting, focus point for SDF and an object distance range for IDF did not differ significantly between time points. Focus was not correlated with difference in fluid balance or weight gain. CONCLUSIONS There is a lack of coherence between surface to capillary distance as determined by SDF or IDF imaging and fluid balance or weight gain. Thus, focal distance as a microvascular index of edema formation cannot currently be used as a proxy for systemic indices of edema formation. However, given the lack of coherence, further research should determine whether focal distance may provide better guidance for fluid therapy than traditional markers of overzealous fluid administration.