Management of Mechanical Ventilation in Decompensated Heart Failure

A multimodal stacked ensemble model for cardiac output prediction utilizing cardiorespiratory interactions during general anesthesia

This study examined the possibility of estimating cardiac output (CO) using a multimodal stacking model that utilizes cardiopulmonary interactions during general anesthesia and outlined a retrospective application of machine learning regression model to a pre-collected dataset. The data of 469 adult patients (obtained from VitalDB) with normal pulmonary function tests who underwent general anesthesia were analyzed. The hemodynamic data in this study included non-invasive blood pressure, plethysmographic heart rate, and SpO2. CO was recorded using Vigileo and EV1000 (pulse contour technique devices). Respiratory data included mechanical ventilation parameters and end-tidal CO2 levels. A generalized linear regression model was used as the metalearner for the multimodal stacking ensemble method. Random forest, generalized linear regression, gradient boosting machine, and XGBoost were used as base learners. A Bland-Altman plot revealed that the multimodal stacked ensemble model for CO prediction from 327 patients had a bias of - 0.001 L/min and - 0.271% when calculating the percentage of difference using the EV1000 device. Agreement of model CO prediction and measured Vigileo CO in 142 patients reported a bias of - 0.01 and - 0.333%. Overall, this model predicts CO compared to data obtained by the pulse contour technique CO monitors with good agreement.

Cardiopulmonary interactions during ventilator weaning

Weaning a critically-ill patient from the ventilator is a crucial step in global management. This manuscript details physiological changes induced by altered heart-lung interactions during the weaning process, illustrates the main mechanisms which could lead to weaning failure of cardiac origin, and discuss a tailored management based on the monitoring of changes in central hemodynamics during weaning. The transition from positive-pressure ventilation to spontaneous breathing results in abrupt hemodynamic and metabolic changes secondary to rapidly modified heart-lung interactions, sudden changes in cardiac loading conditions, and increased oxygen demand. These modifications may elicit an excessive burden on both the respiratory and cardiovascular systems, result in a rapid and marked increase of left ventricular filling pressure, and ultimately result in a weaning-induced pulmonary oedema (WIPO). The T-piece trial induces the greatest burden on respiratory and cardiocirculatory function when compared to spontaneous breathing trial using pressure support ventilation with positive or zero end-expiratory pressure. Since LV overload is the mainstay of WIPO, positive fluid balance and SBT-induced acute hypertension are the most frequently reported mechanisms of weaning failure of cardiac origin. Although the diagnosis of WIPO historically relied on an abrupt elevation of pulmonary artery occlusion pressure measured during right heart catheterization, it is nowadays commonly documented by echocardiography Doppler. This non-invasive approach is best suited for identifying high-risk patients, depicting the origin of WIPO, and tailoring individual management. Whether this strategy increases the success rate of weaning needs to be evaluated in a population at high risk of weaning failure of cardiac origin.

Mitral regurgitation in the critically ill: the devil is in the detail

Mitral regurgitation (MR) is common in the critically unwell and encompasses a heterogenous group of conditions with diverging therapeutic strategies. MR may present acutely with haemodynamic instability or more insidiously with failure to wean from mechanical ventilation. Critical illness is associated with marked physiological stress and haemodynamic changes that dynamically influence the severity and implication of MR. The expanding role of critical care echocardiography uniquely positions the intensivist to apply advanced bedside valvular assessment to recognise haemodynanically significant MR, manipulate and optimise cardiopulmonary physiology and identify patients requiring urgent cardiology and surgical referral. This review will consider common clinical scenarios, therapeutic strategies and the pearls and pitfalls of echocardiographic assessment and quantification in the critically unwell.

High-Sensitivity Cardiac Troponin T in Prediction and Diagnosis of Early Postoperative Hypoxemia after Off-Pump Coronary Artery Bypass Grafting

To investigate the relationship of preoperative high-sensitivity cardiac troponin T (hs-cTnT) with early postoperative hypoxemia (EPH) following off-pump coronary artery bypass grafting (OPCAB). Records of patients undergoing OPCAB between 2018 and 2022 were reviewed. Baseline characteristics and postoperative arterial blood gas analysis were derived from the cardiovascular surgery electronic medical records. Preoperative hs-cTnT levels were measured routinely in all patients. Logistic regression analyses were performed to test the association of preoperative hs-cTnT with EPH. A total of 318 OPCAB patients were included, who had a preoperative hs-cTnT test available for review. Before surgery, 198 patients (62%) had a rise in hs-cTnT level (≥14 ng/L) and 127 patients (40%) had a more severe hs-cTnT level (≥25 ng/L). The preoperative hs-cTnT level was associated with EPH (odds ratio per ng/L, 1.86; 95% confidence interval 1.30−2.68; p < 0.001), prolonged intensive care unit stay (odds ratio, 1.58; 95% confidence interval 1.08−2.32; p = 0.019), and delayed extubating time (odds ratio, 1.63; 95% confidence interval 1.15−2.34; p = 0.007). On multivariable analysis, adjusted for BMI, hypertension, smoking status, serum creatinine, and cardiac function, preoperative hs-cTnT remained an independent factor associated with EPH. Elevation of hs-cTnT concentrations are significantly associated with EPH after OPCAB. Review of presurgical hs-cTnT concentration may help identify patients who would benefit from OPCAB to improve surgical risk assessment.

Retrospective evaluation of the outcome and prognosis of undergoing positive pressure ventilation due to cardiac and noncardiac causes in dogs and cats (2019-2020): 101 cases

OBJECTIVE

To compare the short- and long-term outcomes of dogs and cats with left-sided congestive heart failure (L-CHF) undergoing positive pressure ventilation (PPV) to patients undergoing PPV for other causes and to determine risk factors associated with outcomes in this population.

DESIGN

This retrospective study included dogs and cats that underwent PPV during 2018-2020. The study group included patients diagnosed with L-CHF. The control group included patients who were ventilated for reasons other than L-CHF. The risk factors evaluated included vital signs on presentation, ventilator settings, development of azotemia during hospitalization, cardiopulmonary resuscitation (CPR), complications, and medications used.

SETTING

University Teaching Hospital.

ANIMALS

Fifty (32 dogs, 18 cats) study group animals and 51 (39 dogs, 12 cats) control group animals were included in the L-CHF and control groups, respectively.

MEASUREMENTS AND MAIN RESULTS

Sixty-six percent (33/50) of L-CHF patients, compared with 35% (18/51) of the control patients, were weaned off PPV (P = 0.002). Fifty-four percent (27/50) of the L-CHF patients survived to discharge, compared with 26% (13/51) of the control group patients (P = 0.003). However, only 54% (12/22) of the discharged L-CHF patients survived for >2 months compared to 100% of the control patients. The median survival time for dogs and cats with L-CHF surviving to discharge was 240 days (range: 1-730 days). In dogs, factors negatively associated with survival included CPR in both groups and the development of azotemia in the L-CHF group. Anemia on presentation was negatively associated with survival for both cats and dogs in the control group.

CONCLUSIONS

Dogs and cats undergoing PPV due to L-CHF were more commonly weaned off the ventilator and survived to discharge compared to other causes necessitating PPV. However, these patients suffer from severe heart disease, and therefore, their long-term survival is guaranteed.

Right heart failure: A narrative review for emergency clinicians

INTRODUCTION

Right heart failure (RHF) is a clinical syndrome with impaired right ventricular cardiac output due to a variety of etiologies including ischemia, elevated pulmonary arterial pressure, or volume overload. Emergency department (ED) patients with an acute RHF exacerbation can be diagnostically and therapeutically challenging to manage.

OBJECTIVE

This narrative review describes the pathophysiology of right ventricular dysfunction and pulmonary hypertension, the methods to diagnose RHF in the ED, and management strategies.

DISCUSSION

Right ventricular contraction normally occurs against a low pressure, highly compliant pulmonary vascular system. This physiology makes the right ventricle susceptible to acute changes in afterload, which can lead to RHF. Patients with acute RHF may present with an acute illness and have underlying chronic pulmonary hypertension due to left ventricular failure, pulmonary arterial hypertension, chronic lung conditions, thromboemboli, or idiopathic conditions. Patients can present with a variety of symptoms resulting from systemic edema and hemodynamic compromise. Evaluation with electrocardiogram, laboratory analysis, and imaging is necessary to evaluate cardiac function and end organ injury. Management focuses on treating the underlying condition, optimizing oxygenation and ventilation, treating arrhythmias, and understanding the patient's hemodynamics with bedside ultrasound. As RHF patients are preload dependent they may require fluid resuscitation or diuresis. Hypotension should be rapidly addressed with vasopressors. Cardiac contractility can be augmented with inotropes. Efforts should be made to support oxygenation while trying to avoid intubation if possible.

CONCLUSIONS

Emergency clinician understanding of this condition is important to diagnose and treat this life-threatening cardiopulmonary disorder.

Extubation during extracorporeal membrane oxygenation in adults: An international qualitative study on experts' opinions

BACKGROUND

Extracorporeal membrane oxygenation in adults (adult-ECMO), a modification of cardiopulmonary bypass is increasingly used. Liberation from mechanical ventilation, or extubation, during adult-ECMO remains a challenge.

OBJECTIVES

This study aimed to understand expert perceptions of the reasonableness of extubation during adult-ECMO and the usefulness of an extubation clinical practice guideline (ECPG).

METHODS

Homogeneous purposive sampling, focus groups, and interviews with a discussion guide, and direct content, thematic analysis were used.

RESULTS

Fourteen volunteers participated with different educational levels (79% Doctor of Medicine, 14% Registered Nurse, 7% Nurse Practitioner), from high-volume ECMO centers of various annual ECMO runs (50% 30-49 ECMO/year, 36% 50-99 ECMO/year, 14% >100 ECMO/year) worldwide (64% North America, 21% South America, 7% Europe, 7% Asia). Seven themes were identified: paucity of evidence, mindsets towards using an ECPG, barriers, criteria and benefits of extubation, culture towards extubation and vision of the future. Participants recommended aiming for extubation based on patient selection, and a standardized extubation approach with an ECPG or team decision-making.

CONCLUSION

Application of adult-ECMO is expanding, during which extubation remains difficult. Experts recommend two methods of a standardized extubation approach.

Dynamic prediction of fluid responsiveness during positive pressure ventilation: a review of the physiology underlying heart-lung interactions and a critical interpretation

OBJECTIVE

Cardiovascular responses to hypovolemia and hypotension are depressed during general anesthesia. A considerable number of anesthetized and critically ill animals may not benefit hemodynamically from a fluid bolus; therefore, it is important to have measures for accurate prediction of fluid responsiveness. Static measures of preload, such as central venous pressure, do not provide accurate prediction of fluid responsiveness, whereas dynamic measures of cardiovascular function, obtained during positive pressure ventilation, are highly predictive. This review describes key physiological concepts behind heart-lung interactions during positive pressure ventilation, factors that can modify this relationship and provides the basis for a rational interpretation of the information obtained from dynamic measurements, with a focus on pulse pressure variation (PPV).

DATABASE USED

PubMed. Search items used were: heart-lung interaction, positive pressure ventilation, pulse pressure variation, dynamic index of fluid therapy, goal-directed hemodynamic therapy, dogs, cats, pigs, horses and rabbits.

CONCLUSIONS

The veterinary literature suggests that targeting specific PPV thresholds should guide fluid therapy in lieu of conventional assessments. Understanding the physiology of heart-lung interactions during intermittent positive pressure ventilation provides a rational basis for interpreting the literature on dynamic indices of fluid responsiveness, including PPV. Clinical trials are needed to evaluate whether goal-directed fluid therapy based on PPV results in improved outcomes in veterinary patient populations.

Comparison of clinical efficacy of metoprolol combined with irbesartan and hydrochlorothiazide and non-invasive ventilator in the emergency treatment of patients with severe heart failure

Clinical efficacy of metoprolol combined with irbesartan and hydrochlorothiazide and non-invasive ventilator in the emergency treatment of patients with severe heart failure (HF) was investigated. A retrospective analysis of the medical records of 124 patients with severe HF admitted to Binzhou Medical University Hospital from May 2012 to August 2016 was performed. Among them, 78 patients who were treated with metoprolol combined with irbesartan and hydrochlorothiazide and non-invasive ventilator for emergency treatment were enrolled into the Research Group, while the Control Group consisted of 46 patients treated with routine medical treatment. Echocardiographic parameters, 6-minute walking test results, the efficacy of the emergency treatment, cardiac function grading, left ventricular ejection fraction (LVEF) and brain natriuretic peptide (BNP) levels were compared between the two groups. After the emergency treatment, the echocardiographic indexes of both groups increased to different extents (P<0.05). Compared with the results before, patients of both groups walked longer within six minutes after the emergency treatment (P<0.05). After the emergency treatment, the BNP expression levels in the two groups decreased to different degrees (P<0.05). After a 7-day emergency treatment, the efficiency rate of treatment of the Research Group was higher than that of the Control Group (P<0.05). The method is helpful for the recovery of respiratory function, for relieving symptoms in short time, improving cardiac function and promising high safety, using metoprolol and irbesartan and hydrochlorothiazide combined with non-invasive ventilator had satisfactory clinical efficacy in the emergency treatment of patients with severe heart failure and is thus worthy of clinical promotion.

Cardiovascular failure and weaning

Cardiac patients are at high risk of weaning failure due to the abrupt burden to the cardiovascular system resulting from the transition from positive-pressure ventilation to spontaneous breathing. Similarly, numerous patients with borderline cardiac function, left ventricular diastolic dysfunction, chronic obstructive pulmonary disease, especially with associated fluid overload or cumulative positive fluid balance, are at high risk of weaning failure of cardiac origin. The diagnosis of weaning-induced pulmonary oedema (WiPO) relies on the measurement of elevated left ventricular filling pressure, or on the presence of a surrogate reflecting pulmonary or cardiac congestion. Plasma concentration of B-type natriuretic peptide and N-terminal proBNP, biological signs of hemoconcentration (increased circulating protein or hemoglobin levels), or measurement of extravascular pulmonary lung water using transpulmonary thermodilution have been proved valuable surrogates for the identification of weaning failure. Nevertheless, studies have not yet compared these indirect methods to precisely determine their respective diagnostic values for the identification of WiPO, especially in heart failure patients. In addition, none of these approaches directly assess left ventricular filling pressure and the mechanism of WiPO. In contrast, critical care echocardiography is ideally suited to establish the diagnosis of weaning failure of cardiac origin. It allows identifying the high-risk population, monitoring hemodynamically the patient at risk, depicting an abrupt increase of left ventricular filling pressure consistent with WiPO when the patient fails weaning, identifying the underlying mechanism of WiPO, and finally it allows tailoring the therapeutic management of the patient who failed weaning. The impact on patient-centered outcomes of such integrated management strategy based on critical care echocardiography deserves to be prospectively tested in a large population of patients at high risk of weaning failure of cardiac origin.