The gray zone of the qualitative assessment of respiratory changes in inferior vena cava diameter in ICU patients

The use of bedside echocardiography in the care of critically ill patients - a joint consensus document of the Associação de Medicina Intensiva Brasileira, Associação Brasileira de Medicina de Emergência and Sociedade Brasileira de Medicina Hospitalar. Part 2 - Technical aspects

Echocardiography in critically ill patients has become essential in the evaluation of patients in different settings, such as the hospital. However, unlike for other matters related to the care of these patients, there are still no recommendations from national medical societies on the subject. The objective of this document was to organize and make available expert consensus opinions that may help to better incorporate echocardiography in the evaluation of critically ill patients. Thus, the Associação de Medicina Intensiva Brasileira, the Associação Brasileira de Medicina de Emergência, and the Sociedade Brasileira de Medicina Hospitalar formed a group of 17 physicians to formulate questions relevant to the topic and discuss the possibility of consensus for each of them. All questions were prepared using a five-point Likert scale. Consensus was defined a priori as at least 80% of the responses between one and two or between four and five. The consideration of the issues involved two rounds of voting and debate among all participants. The 27 questions prepared make up the present document and are divided into 4 major assessment areas: left ventricular function, right ventricular function, diagnosis of shock, and hemodynamics. At the end of the process, there were 17 positive (agreement) and 3 negative (disagreement) consensuses; another 7 questions remained without consensus. Although areas of uncertainty persist, this document brings together consensus opinions on several issues related to echocardiography in critically ill patients and may enhance its development in the national scenario.

Lack of correlation between different congestion markers in acute decompensated heart failure

BACKGROUND

Hospitalizations for acute decompensated heart failure (ADHF) are commonly associated with congestion-related signs and symptoms. Objective and quantitative markers of congestion have been identified, but there is limited knowledge regarding the correlation between these markers.

METHODS

Patients hospitalized for ADHF irrespective of left ventricular ejection fraction were included in a prospective registry. Assessment of congestion markers (e.g., NT-proBNP, maximum inferior vena cava diameter, dyspnea using visual analogue scale, and a clinical congestion score) was performed systematically on admission and at discharge. Telephone interviews were performed to assess clinical events, i.e., all-cause death or readmission for cardiovascular cause, after discharge. Missing values were handled by multiple imputation.

RESULTS

In total, 130 patients were prospectively enrolled. Median length of hospitalization was 9 days (interquartile range 6 to 16). All congestion markers declined from admission to discharge (p < 0.001). No correlation between the congestion markers could be identified, neither on admission nor at discharge. The composite endpoint of all-cause death or readmission for cardiovascular cause occurred in 46.2% of patients. Only NT-proBNP at discharge was predictive for this outcome (hazard ratio 1.48, 95% confidence interval 1.15 to 1.90, p = 0.002).

CONCLUSION

No correlation between quantitative congestion markers was observed. Only NT-proBNP at discharge was significantly associated with the composite endpoint of all-cause death or readmission for cardiovascular cause. Findings indicate that the studied congestion markers reflect different aspects of congestion.

Preoperative assessment of inferior vena cava collapsibility index by ultrasound is not a reliable predictor of post-spinal anesthesia hypotension

BACKGROUND

Post-spinal anesthesia hypotension is of common occurrence, and it hampers tissue perfusion. Several preoperative factors determine patient susceptibility to hypotension. This study aimed to assess the effectiveness of the Inferior Vena Cava Collapsibility Index (IVCCI) for predicting intraoperative hypotension.

METHODS

One hundred twenty-nine adult patients who were scheduled for elective surgical procedures after administration of spinal (intrathecal) anesthesia were included in the study. Ultrasound evaluation of the Inferior Vena Cava (IVC) was done in the preoperative area, and the patients were shifted to the Operating Room (OR) for spinal anesthesia. An independent observer recorded the change in blood pressure after spinal anesthesia inside the OR.

RESULTS

Twenty-five patients developed hypotension (19.37%). Baseline systolic blood pressure and mean blood pressures were statistically higher in those patients who developed hypotension (p = 0.001). The logistic regression analysis for IVCCI and the incidence of hypotension showed r² of 0.025. Receiver Operating Characteristic (ROC) curve analysis demonstrated the Area Under the Curve (AUC) of 0.467 (95% Confidence Interval, 0.338 to 0.597; p = 0.615).

CONCLUSIONS

Preoperative evaluation of IVCCI is not a good predictor for the occurrence of hypotension after spinal anesthesia.

Ultrasound Assessment of the Inferior Vena Cava for Fluid Responsiveness: Making the Case for Skepticism

Determining whether a patient in shock is in a state of fluid responsiveness (FR) has long been the Holy Grail for clinicians who care for acutely ill patients. While various tools have been put forth as solutions to this important problem, ultrasound assessment of the inferior vena cava has received particular attention of late. Dozens of studies have examined its ability to determine whether a patient should receive volume expansion, and general enthusiasm has been strengthened by the fact that it is easy to perform and non-invasive, unlike many competing FR tests. A deeper examination of the technique, however, reveals important concerns regarding inaccuracies in measurement and a high prevalence of confounding factors. Furthermore, a detailed review of the evidence (small individual studies, multiple meta-analyses, and a single large trial) reveals that the tool performs poorly in general and is unlikely to be helpful at the bedside in circumstances where genuine clinical uncertainty exists.

Perioperative echocardiography-guided hemodynamic therapy in high-risk patients: a practical expert approach of hemodynamically focused echocardiography

The number of high-risk patients undergoing surgery is growing. To maintain adequate hemodynamic functioning as well as oxygen delivery to the vital organs (DO2) amongst this patient population, a rapid assessment of cardiac functioning is essential for the anesthesiologist. Pinpointing any underlying cardiovascular pathophysiology can be decisive to guide interventions in the intraoperative setting. Various techniques are available to monitor the hemodynamic status of the patient, however due to intrinsic limitations, many of these methods may not be able to directly identify the underlying cause of cardiovascular impairment. Hemodynamic focused echocardiography, as a rapid diagnostic method, offers an excellent opportunity to examine signs of filling impairment, cardiac preload, myocardial contractility and the function of the heart valves. We thus propose a 6-step-echocardiographic approach to assess high-risk patients in order to improve and maintain perioperative DO2. The summary of all echocardiographic based findings allows a differentiated assessment of the patient's cardiovascular function and can thus help guide a (patho)physiological-orientated and individualized hemodynamic therapy.

[Perioperative optimization using hemodynamically focused echocardiography in high-risk patients-A practice guide]

BACKGROUND

The number of high-risk patients undergoing surgery is steadily increasing. In order to maintain and, if necessary, optimize perioperative hemodynamics as well as the oxygen supply to the organs (DO₂) in this patient population, a timely assessment of cardiac function and the underlying pathophysiological causes of hemodynamic instability is essential for the anesthesiologist. A variety of hemodynamic monitoring procedures are available for this purpose; however, due to method-immanent limitations they are often not able to directly identify the underlying cause of cardiovascular impairment.

OBJECTIVE

To present a stepwise algorithm for a perioperative echocardiography-based hemodynamic optimization in noncardiac surgery high-risk patients. In this context, echocardiography on demand according to international guidelines can be performed under certain conditions (hemodynamic instability, nonresponse to hemodynamic treatment) as well as in the context of a planned intraoperative procedure, mostly as a transesophageal echocardiography.

METHODS AND RESULTS

Hemodynamically focused echocardiography as a rapidly available bedside method, enables the timely diagnosis and assessment of cardiac filling obstructions, volume status and volume response, right and left heart function, and the function of the heart valves.

CONCLUSION

Integrating all echocardiographic findings in a differentiated assessment of the patient's cardiovascular function enables a (patho)physiologically oriented and individualized hemodynamic treatment.

Point of Care Ultrasonography for Objective Assessment of Heart Failure: Integration of Cardiac, Vascular, and Extravascular Determinants of Volume Status

BACKGROUND

Lingering congestion portends poor outcomes in patients with heart failure (HF) and is a key target in their management. Studies have shown that physical exam has low yield in this setting and conventional methods for more precise assessment and monitoring of volume status (e.g., body weight, natriuretic peptides, and chest radiography) have significant inherent shortcomings.

SUMMARY

Point of care ultrasonography (POCUS) is a noninvasive versatile bedside diagnostic tool that enhances the sensitivity of conventional physical examination to gauge congestion in these patients. It also aids in monitoring the efficacy of decongestive therapy and bears prognostic significance. In this narrative review, we discuss the role of focused sonographic assessment of the heart, venous system, and extravascular lung water/ascites (i.e., the pump, pipes, and the leaks) in objective assessment of fluid volume status. Key Messages: Since each of the discussed components of POCUS has its limitations, a combinational ultrasound evaluation guided by the main clinical features would be the key to reliable assessment and effective management of congestion in patients with HF.

Ultrasonographic inferior vena cava diameter response to trauma resuscitation after 1 hour predicts 24-hour fluid requirement

BACKGROUND

Identification of occult hypovolemia in trauma patients is difficult. We hypothesized that in acute trauma patients, the response of ultrasound-measured minimum inferior vena cava diameter (IVCDMIN), IVC Collapsibility Index (IVCCI), minimum internal jugular diameter (IJVDMIN) or IJV Collapsibility Index (IJVCI) after up to 1 hour of fluid resuscitation would predict 24-hour resuscitation intravenous fluid requirements (24FR).

METHODS

An NTI-funded, American Association for the Surgery of Trauma Multi-Institutional Trials Committee prospective, cohort trial was conducted at four Level I Trauma Centers. Major trauma patients were screened for an IVCD of 12 mm or less or IVCCI of 50% or less on initial focused assessment sonographic evaluations for trauma. A second IVCD was obtained 40 minutes to 60 minutes later, after standard-of-care fluid resuscitation. Patients whose second measured IVCD was less than 10 mm were deemed nonrepleted (NONREPLETED), those 10 mm or greater were repleted (REPLETED). Prehospital and initial resuscitation fluids and 24FR were recorded. Demographics, Injury Severity Score, arterial blood gasses, length of stay, interventions, and complications were recorded. Means were compared by ANOVA and categorical variables were compared via χ. Receiver operating characteristic curves analysis was used to compare the measures as 24FR predictors.

RESULTS

There were 4,798 patients screened, 196 were identified with admission IVCD of 12 mm or IVCCI of 50% or less, 144 were enrolled. There were 86 REPLETED and 58 NONREPLETED. Demographics, initial hemodynamics, or laboratory measures were not significantly different. NONREPLETED had smaller IVCD (6.0 ± 3.7 mm vs. 14.2 ± 4.3 mm, p < 0.001) and higher IVCCI (41.7% ± 30.0% vs. 13.2% ± 12.7%, p < 0.001) but no significant difference in IJVD or IJVCCI. REPLETED had greater 24FR than NONREPLETED (2503 ± 1751 mL vs. 1,243 ± 1,130 mL, p = 0.003). Receiver operating characteristic analysis indicates IVCDMIN predicted 24FR (area under the curve [AUC], 0.74; 95% confidence interval [CI], 0.64-0.84; p < 0.001) as did IVCCI (AUC, 0.75; 95% CI, 0.65-0.85; p < 0.001) but not IJVDMIN (AUC, 0.48; 95% CI, 0.24-0.60; p = 0.747) or IJVCI (AUC, 0.54; 95% CI, 0.42-0.67; p = 0.591).

CONCLUSION

Ultrasound assessed IVCDMIN and IVCCI response initial resuscitation predicts 24-hour fluid resuscitation requirements.

LEVEL OF EVIDENCE

Diagnostic tests or criteria, level II.

Ultrasound in Austere Environments

Ultrasonography is a noninvasive, reliable, repeatable, and inexpensive technology that has dramatically changed the practice of medicine. The clinical use of portable ultrasound devices has grown tremendously over the last 10 years in the fields of intensive care, emergency medicine, and anesthesiology. In this review we present the various ways that handheld portable ultrasound devices can be used in austere environments. The purpose of this review is to consider the wide-ranging applications for providers going into the austere environment, which include pulmonary, ocular, vascular, and trauma evaluations, the postdisaster setting, and the role of ultrasonography in tropical diseases. This review is not meant to be a comprehensive how-to guide for each study type, but an overview of some of the more common wilderness applications. This review also focuses on the limitation of each study type. The goal is to help wilderness medicine providers feel more comfortable incorporating ultrasonography as part of their tool kit when heading into austere environments.

The PIEPEAR Workflow: A Critical Care Ultrasound Based 7-Step Approach as a Standard Procedure to Manage Patients with Acute Cardiorespiratory Compromise, with Two Example Cases Presented

Critical care ultrasound (CCUS) has been widely used as a useful tool to assist clinical judgement. The utilization should be integrated into clinical scenario and interact with other tests. No publication has reported this. We present a CCUS based "7-step approach" workflow-the PIEPEAR Workflow-which we had summarized and integrated our experience in CCUS and clinical practice into, and then we present two cases which we have applied the workflow into as examples. Step one is "problems emerged?" classifying the signs of the deterioration into two aspects: acute circulatory compromise and acute respiratory compromise. Step two is "information clear?" quickly summarizing the patient's medical history by three aspects. Step three is "focused exam launched": (1) focused exam of the heart by five views: the assessment includes (1) fast and global assessment of the heart (heart glance) to identify cases that need immediate life-saving intervention and (2) assessing the inferior vena cava, right heart, diastolic and systolic function of left heart, and systematic vascular resistance to clarify the hemodynamics. (2) Lung ultrasound exam is performed to clarify the predominant pattern of the lung. Step four is "pathophysiologic changes reported." The results of the focused ultrasound exam were integrated to conclude the pathophysiologic changes. Step five is "etiology explored" diagnosing the etiology by integrating Step two and Step four and searching for the source of infection, according to the clues extracted from the focused ultrasound exam; additional ultrasound exams or other tests should be applied if needed. Step six is "action" supporting the circulation and respiration sticking to Step four. Treat the etiologies according step five. Step seven is "recheck to adjust." Repeat focused ultrasound and other tests to assess the response to treatment, adjust the treatment if needed, and confirm or correct the final diagnosis. With two cases as examples presented, we insist that applying CCUS with 7-step approach workflow is easy to follow and has theoretical advantages. The coming research on its value is expected.

Holistic ultrasound in trauma: An update

Holistic ultrasound is a total body examination using an ultrasound device aiming to achieve immediate patient care and decision making. In the setting of trauma, it is one of the most fundamental components of care of the injured patients. Ground-breaking imaging software allows physicians to examine various organs thoroughly, recognize imaging signs early, and potentially foresee the onset or the possible outcome of certain types of injuries. Holistic ultrasound can be performed on a routine basis at the bedside of the patients, at admission and during the perioperative period. Trauma care physicians should be aware of the diagnostic and guidance benefits of ultrasound and should receive appropriate training for the optimal management of their patients. In this paper, the findings of holistic ultrasound in trauma patients are presented, with emphasis on the lungs, heart, cerebral circulation, abdomen, and airway. Additionally, the benefits of ultrasound imaging in interventional anaesthesia techniques such as ultrasound-guided peripheral nerve blocks and central vein catheterization are described.

The diagnostic validity of clinical airway assessments for predicting difficult laryngoscopy using a grey zone approach

Objectives

The diagnostic validity of clinical airway assessment tests for predicting difficult laryngoscopy in patients requiring endotracheal intubation were evaluated using receiver operating characteristic (ROC) curve analysis and a grey zone approach.

Methods

In this prospective observational study, patients were evaluated during a pre-anaesthetic visit. Predictive airway assessment tests (i.e. Modified Mallampati [MMT] classification; upper lip bite test [ULBT]; mouth opening; sternomental distance; thyromental distance [TMD]; neck circumference; neck mobility; height to thyromental distance [HT/TMD]; neck circumference-to-thyromental distance [NC/TMD]) were performed on each patient and LEMON, Naguib, and MACOCHA scores were also calculated. In addition, laryngeal images were acquired and assessed for percentage of glottic opening (POGO) scores. A POGO score of zero was categorized as difficult laryngoscopy.

Results

The incidence of difficult laryngoscopy was 14.4% (35/243). Although seven predictive airway assessments (i.e. MMT classification, ULBT, mouth opening, HT/TMD, NC/TMD, and the LEMON and Naguib models) predicted difficult laryngoscopy by ROC analyses, a grey zone approach showed that the parameters were inconclusive in approximately 70% of patients. From all the tests, the HT/TMD ratio showed the highest sensitivity (80.0%) and ULBT had the highest specificity (95.2%).

Conclusion

Using the grey zone approach, all predictive airway assessment tests showed large inconclusive zones which may explain previous inconsistent results in the prediction of difficult laryngoscopy. Our results suggest that the usefulness of clinical airway evaluation tests for predicting difficult laryngoscopy remains controversial.

Clinical trial registration

ClinicalTrials.gov (NCT01719848)

Inferior Vena Cava Ultrasonography before General Anesthesia Can Predict Hypotension after Induction

Background

Hypotension is a common side effect of general anesthesia induction, and when severe, it is related to adverse outcomes. Ultrasonography of inferior vena cava (IVC) is a reliable indicator of intravascular volume status. This study investigated whether preoperative ultrasound IVC measurements could predict hypotension after induction of anesthesia.

Methods

One hundred four adult patients, conforming to American Society of Anesthesiologists physical status I to III, scheduled for elective surgery after general anesthesia were recruited. Maximum IVC diameter (dIVCmax) and collapsibility index (CI) were measured preoperatively. Before induction, mean blood pressure (MBP) was recorded. After induction, MBP was recorded for 10 min after intubation. Hypotension was defined as greater than 30% decrease in MBP from baseline or MBP less than 60 mmHg. Receiver operating characteristic curve analysis with gray zone approach and regression analyses were used.

Results

IVC scanning was unsuccessful in 13.5% of patients. Data from 90 patients were analyzed. After induction, 42 patients developed hypotension. Areas (95% confidence interval) under the curves were 0.90 (0.82 to 0.95) for CI and 0.76 (0.66 to 0.84) for dIVCmax. The optimal cutoff values were 43% for CI and 1.8 cm for dIVCmax. The gray zone for CI was 38 to 43% and included 12% of patients and that for dIVCmax was 1.5 to 2.1 cm and included 59% of patients. After adjusting for other factors, it was found that CI was an independent predictor of hypotension with the odds ratio of 1.17 (1.09 to 1.26). CI was also positively associated with a percentage decrease in MBP (regression coefficient = 0.27).

Conclusions

Preoperative ultrasound IVC CI measurement was a reliable predictor of hypotension after induction of general anesthesia, wherein CI greater than 43% was the threshold.

Predicting outcome from dengue

Dengue is emerging as one of the most abundant vector-borne disease globally. Although the majority of infections are asymptomatic or result in only a brief systemic viral illness, a small proportion of patients develop potentially fatal complications. These severe manifestations, including a unique plasma leakage syndrome, a coagulopathy sometimes accompanied by bleeding, and organ impairment, occur relatively late in the disease course, presenting a window of opportunity to identify the group of patients likely to progress to these complications. However, as yet, differentiating this group from the thousands of milder cases seen each day during outbreaks remains challenging, and simple and inexpensive strategies are urgently needed in order to improve case management and to facilitate appropriate use of limited resources. This review will cover the current understanding of the risk factors associated with poor outcome in dengue. We focus particularly on the clinical features of the disease and on conventional investigations that are usually accessible in mid-level healthcare facilities in endemic areas, and then discuss a variety of viral, immunological and vascular biomarkers that have the potential to improve risk prediction. We conclude with a description of several novel methods of assessing vascular function and intravascular volume status non-invasively.