Assessing Fluid Intolerance with Doppler Ultrasonography: A Physiological Framework

Echocardiography in the Ventilated Patient: What the Clinician Has to Know

Heart and lung sharing the same anatomical space are influenced by each other. Spontaneous breathing induces dynamic changes in intrathoracic pressure, impacting cardiac function, particularly the right ventricle. In intensive care units (ICU), mechanical ventilation (MV) and therefore positive end-expiratory pressure (PEEP) are often applied, and this inevitably influences cardiac function. In ventilated patients, the use of positive pressures leads to an increase in intrathoracic pressure and, consequently, to a reduction in the right ventricular preload and thus cardiac output. The clinician working in the intensive care unit must be able to assess the effects MV has on the heart in order to set it up appropriately and to manage any complications. The echocardiographic evaluation of the ventilated patient has the main purpose of studying the right ventricle; in fact, they are the ones most affected by PEEP. It is therefore necessary to assess the size, thickness, and systolic function of the right ventricle. In the mechanically ventilated patient, it may be difficult to assess the volemic status and fluid responsiveness, in fact, the study of the inferior vena cava (IVC) is not always reliable in these patients. In patients with MV, it is preferable to assess fluid responsiveness with dynamic methods such as the end-expiration occlusion (EEO) test, passive leg raise (PLR), and fluid challenge (FC). The study of the diaphragm is also essential to identify possible complications, manage weaning, and provide important prognostic information. This review describes the basis for echocardiographic evaluation of the mechanically ventilated patient with the aim of supporting the clinician in managing the consequences of MV for heart-lung interaction.

A nursing-led sepsis response team guiding resuscitation with point-of-care ultrasound: A review and model for improving bundle compliance while individualizing sepsis care

A dysregulated host response to infection resulting in life-threatening organ dysfunction defines the onset of sepsis. Unfortunately, sepsis is common, costly, and deadly. The Surviving Sepsis Campaign publishes regularly updated, evidence-informed, detection, and treatment guidelines culminating in time-sensitive care "bundles." The goal of these bundles is to expedite sepsis recognition because it is widely held that early treatment is life-saving. Hospitals are mandated to publicly report their bundle compliance, and this will soon be tied to hospital reimbursement. For these reasons, hospitals are creating sepsis emergency response teams which are a form of a rapid response team consisting of dedicated medical professionals who evaluate patients with suspected sepsis and initiate therapy when appropriate. Evidence to date support sepsis emergency response teams as a mechanism to improve bundle compliance, and potentially, patient outcome. Nevertheless, some elements of bundled sepsis care are controversial (e.g., intravenous fluid administration) as some argue that mandated treatment precludes personalized care. Herein, we briefly describe general sepsis emergency response team structure, review evidence supporting sepsis emergency response teams to improve bundle compliance and patient outcome and report our unique experience incorporating point of care ultrasound-to guide intravenous fluid-into a nursing-led sepsis team. We propose that our sepsis emergency response team approach allays concern that sepsis care is either bundled or personalized. Instead, incorporating point of care ultrasound into a nursing-led sepsis emergency response team increases bundle compliance and individualizes care.

A Multivariate Phenotypical Approach of Sepsis and Septic Shock-A Comprehensive Narrative Literature Review

Despite medical advances, sepsis and septic shock remain some of the leading causes of mortality worldwide, with a high inter-individual variability in prognosis, clinical manifestations and response to treatment. Evidence suggests that pulmonary sepsis is one of the most severe forms of sepsis, while liver dysfunction, left ventricular dysfunction, and coagulopathy impact the prognostic. Sepsis-related hypothermia and a hypoinflammatory state are related to a poor outcome. Given the heterogeneity of sepsis and recent technological progress amongst machine learning analysis techniques, a new, personalized approach to sepsis is being intensively studied. Despite the difficulties when tailoring a targeted approach, with the use of artificial intelligence-based pattern recognition, more and more publications are becoming available, highlighting novel factors that may intervene in the high heterogenicity of sepsis. This has led to the devise of a phenotypical approach in sepsis, further dividing patients based on host and trigger-related factors, clinical manifestations and progression towards organ deficiencies, dynamic prognosis algorithms, and patient trajectory in the Intensive Care Unit (ICU). Host and trigger-related factors refer to patients' comorbidities, body mass index, age, temperature, immune response, type of bacteria and infection site. The progression to organ deficiencies refers to the individual particularities of sepsis-related multi-organ failure. Finally, the patient's trajectory in the ICU points out the need for a better understanding of interindividual responses to various supportive therapies. This review aims to identify the main sources of variability in clustering septic patients in various clinical phenotypes as a useful clinical tool for a precision-based approach in sepsis and septic shock.

Coexistence of a fluid responsive state and venous congestion signals in critically ill patients: a multicenter observational proof-of-concept study

BACKGROUND

Current recommendations support guiding fluid resuscitation through the assessment of fluid responsiveness. Recently, the concept of fluid tolerance and the prevention of venous congestion (VC) have emerged as relevant aspects to be considered to avoid potentially deleterious side effects of fluid resuscitation. However, there is paucity of data on the relationship of fluid responsiveness and VC. This study aims to compare the prevalence of venous congestion in fluid responsive and fluid unresponsive critically ill patients after intensive care (ICU) admission.

METHODS

Multicenter, prospective cross-sectional observational study conducted in three medical-surgical ICUs in Chile. Consecutive mechanically ventilated patients that required vasopressors and admitted < 24 h to ICU were included between November 2022 and June 2023. Patients were assessed simultaneously for fluid responsiveness and VC at a single timepoint. Fluid responsiveness status, VC signals such as central venous pressure, estimation of left ventricular filling pressures, lung, and abdominal ultrasound congestion indexes and relevant clinical data were collected.

RESULTS

Ninety patients were included. Median age was 63 [45-71] years old, and median SOFA score was 9 [7-11]. Thirty-eight percent of the patients were fluid responsive (FR+), while 62% were fluid unresponsive (FR-). The most prevalent diagnosis was sepsis (41%) followed by respiratory failure (22%). The prevalence of at least one VC signal was not significantly different between FR+ and FR- groups (53% vs. 57%, p = 0.69), as well as the proportion of patients with 2 or 3 VC signals (15% vs. 21%, p = 0.4). We found no association between fluid balance, CRT status, or diagnostic group and the presence of VC signals.

CONCLUSIONS

Venous congestion signals were prevalent in both fluid responsive and unresponsive critically ill patients. The presence of venous congestion was not associated with fluid balance or diagnostic group. Further studies should assess the clinical relevance of these results and their potential impact on resuscitation and monitoring practices.

Challenges in Septic Shock: From New Hemodynamics to Blood Purification Therapies

Sepsis and septic shock are associated with high mortality, with diagnosis and treatment remaining a challenge for clinicians. Their management classically encompasses hemodynamic resuscitation, antibiotic treatment, life support, and focus control; however, there are aspects that have changed. This narrative review highlights current and avant-garde methods of handling patients experiencing septic shock based on the experience of its authors and the best available evidence in a context of uncertainty. Following the first recommendation of the Surviving Sepsis Campaign guidelines, it is recommended that specific sepsis care performance improvement programs are implemented in hospitals, i.e., "Sepsis Code" programs, designed ad hoc, to achieve this goal. Regarding hemodynamics, the importance of perfusion and hemodynamic coherence stand out, which allow for the recognition of different phenotypes, determination of the ideal time for commencing vasopressor treatment, and the appropriate fluid therapy dosage. At present, this is not only important for the initial timing, but also for de-resuscitation, which involves the early weaning of support therapies, directed elimination of fluids, and fluid tolerance concept. Finally, regarding blood purification therapies, those aimed at eliminating endotoxins and cytokines are attractive in the early management of patients in septic shock.

Point-of-Care Ultrasound-History, Current and Evolving Clinical Concepts in Emergency Medicine

Point-of-care ultrasound (PoCUS) has become an indispensable standard in emergency medicine. Emergency medicine ultrasound (EMUS) is the application of bedside PoCUS by the attending emergency physician to assist in the diagnosis and management of many time-sensitive health emergencies. In many ways, using PoCUS is not only the mere application of technology, but also a fusion of already existing examiner skills and technology in the context of a patient encounter. EMUS practice can be defined using distinct anatomy-based applications. The type of applications and their complexity usually depend on local needs and resources, and practice patterns can vary significantly among regions, countries, or even continents. A different approach suggests defining EMUS in categories such as resuscitative, diagnostic, procedural guidance, symptom- or sign-based, and therapeutic. Because EMUS is practiced in a constantly evolving emergency medical setting where no two patient encounters are identical, the concept of EMUS should also be practiced in a fluid, constantly adapting manner driven by the physician treating the patient. Many recent advances in ultrasound technology have received little or no attention from the EMUS community, and several important technical advances and research findings have not been translated into routine clinical practice. The authors believe that four main areas have great potential for the future growth and development of EMUS and are worth integrating: 1. In recent years, many articles have been published on novel ultrasound applications. Only a small percentage has found its way into routine use. We will discuss two important examples: trauma ultrasound that goes beyond e-FAST and EMUS lung ultrasound for suspected pulmonary embolism. 2. The more ultrasound equipment becomes financially affordable; the more ultrasound should be incorporated into the physical examination. This merging and possibly even replacement of aspects of the classical physical exam by technology will likely outperform the isolated use of stethoscope, percussion, and auscultation. 3. The knowledge of pathophysiological processes in acute illness and ultrasound findings should be merged in clinical practice. The translation of this knowledge into practical concepts will allow us to better manage many presentations, such as hypotension or the dyspnea of unclear etiology. 4. Technical innovations such as elastography; CEUS; highly sensitive color Doppler such as M-flow, vector flow, or other novel technology; artificial intelligence; cloud-based POCUS functions; and augmented reality devices such as smart glasses should become standard in emergencies over time.

Inferior Vena Caval Measures Do Not Correlate with Carotid Artery Corrected Flow Time Change Measured Using a Wireless Doppler Patch in Healthy Volunteers

(1) Background: The inspiratory collapse of the inferior vena cava (IVC), a non-invasive surrogate for right atrial pressure, is often used to predict whether a patient will augment stroke volume (SV) in response to a preload challenge. There is a correlation between changing stroke volume (SV∆) and corrected flow time of the common carotid artery (ccFT∆). (2) Objective: We studied the relationship between IVC collapsibility and ccFT∆ in healthy volunteers during preload challenges. (3) Methods: A prospective, observational, pilot study in euvolemic, healthy volunteers with no cardiovascular history was undertaken in a local physiology lab. Using a tilt-table, we studied two degrees of preload augmentation from (a) supine to 30-degrees head-down and (b) fully-upright to 30-degrees head down. In the supine position, % of IVC collapse with respiration, sphericity index and portal vein pulsatility was calculated. The common carotid artery Doppler pulse was continuously captured using a wireless, wearable ultrasound system. (4) Results: Fourteen subjects were included. IVC % collapse with respiration ranged between 10% and 84% across all subjects. Preload responsiveness was defined as an increase in ccFT∆ of at least 7 milliseconds. A total of 79% (supine baseline) and 100% (head-up baseline) of subjects were preload-responsive. No supine venous measures (including IVC % collapse) were significantly related to ccFT∆. (5) Conclusions: From head-up baseline, 100% of healthy subjects were 'preload-responsive' as per the ccFT∆. Based on the 42% and 25% IVC collapse thresholds in the supine position, only 50% and 71% would have been labeled 'preload-responsive'.

Unifying Fluid Responsiveness and Tolerance With Physiology: A Dynamic Interpretation of the Diamond-Forrester Classification

Point of care ultrasound (POCUS) is a first-line tool to assess hemodynamically unstable patients, however, there is confusion surrounding intertwined concepts such as: "flow," "congestion," "fluid responsiveness (FR)," and "fluid tolerance." We argue that the Frank-Starling relationship is clarifying because it describes the interplay between "congestion" and "flow" on the x-axis and y-axis, respectively. Nevertheless, a single, simultaneous assessment of congestion and flow via POCUS remains a static approach. To expand this, we propose a two-step process. The first step is to place the patient on an ultrasonographic Diamond-Forrester plot. The second step is a dynamic assessment for FR (e.g., passive leg raise), which individualizes therapy across the arc of critical illness.

Point-of-Care Ultrasound: A Multimodal Tool for the Management of Sepsis in the Emergency Department

Sepsis and septic shock are life-threatening emergencies associated with increased morbidity and mortality. Hence, early diagnosis and management of both conditions is of paramount importance. Point-of-care ultrasound (POCUS) is a cost-effective and safe imaging modality performed at the bedside, which has rapidly emerged as an excellent multimodal tool and has been gradually incorporated as an adjunct to physical examination in order to facilitate evaluation, diagnosis and management. In sepsis, POCUS can assist in the evaluation of undifferentiated sepsis, while, in cases of shock, it can contribute to the differential diagnosis of other types of shock, thus facilitating the decision-making process. Other potential benefits of POCUS include prompt identification and control of the source of infection, as well as close haemodynamic and treatment monitoring. The aim of this review is to determine and highlight the role of POCUS in the evaluation, diagnosis, treatment and monitoring of the septic patient. Future research should focus on developing and implementing a well-defined algorithmic approach for the POCUS-guided management of sepsis in the emergency department setting given its unequivocal utility as a multimodal tool for the overall evaluation and management of the septic patient.