[Assessment of cardiovascular preload and response to volume expansion]

Increased preload and echocardiographic assessment of diastolic function

AIMS

Echocardiographic diastolic parameters are used to diagnose and monitor increased left ventricular filling pressure (LVFP) and we hypothesized that increased loading conditions cause increased E/e'. Our aim was to assess the effect of preload augmentation on diastolic parameters among both healthy subjects and subjects with known cardiac disease.

METHODS AND RESULTS

We included 129 subjects merged from two cohorts; one dialysis cohort (n = 47) and one infusion cohort (n = 82). Echocardiography was performed immediately before and after hemodialysis (HD) or saline infusion, under low and high loading conditions. Elevated LVFP was defined as septal E/e' ≥ 15 and/or lateral E/e' ≥ 13 at high-loading conditions. The population was divided according to elevated LVFP (n = 31) and normal LVFP (n = 98). The load difference for the population was 972 ± 460 mL, with no differences in load difference between elevated and normal LVFP (p NS). The subjects with elevated LVFP were older (63 ± 11 vs. 46 ± 16 years, p < .001), and had lower LV ejection fraction (50 ± 14 vs. 59 ± 8.1%, p < .01). After augmented preload, EDV increased in the normal LVFP group (p < .01) but remained unchanged in the elevated LVFP group (p NS). Both E and e' increased among the subjects with normal LVFP, whereas E/e' remained unchanged (∆E/e' +.1 [-.5-1.2]), p NS). Among the subjects with elevated, LVFP we observed increased E but not e', resulting in significantly increased E/e' (∆ average E/e' +2.4 [0-4.0], p < .01).

CONCLUSION

Augmented preload does not seem to affect E/e' among subjects with normal LVFP, whereas E/e' seems to increase significantly among subjects with elevated LVFP.

[Resuscitation strategy for patients with sepsis and septic shock]

Fluid and vasopressor resuscitation is, along with antimicrobial therapy and control of the focus of infection, a basic issue of the treatment of sepsis and septic shock. There is currently no accepted protocol that we can follow for the resuscitation of these patients and the Surviving Sepsis Campaign proposes controversial measures and without sufficient evidence support to establish firm recommendations. We propose a resuscitation strategy adapted to the situation of each patient: in the patient in whom community sepsis is suspected, we consider that the early administration of 30mL/kg of crystalloids is effective and safe; in the patient with nosocomial sepsis, we must carry out a more in-depth evaluation before initiating aggressive resuscitation. In patients who do not respond to initial resuscitation, it is necessary to increase monitoring level and, depending on the hemodynamic profile, administer more fluids, a second vasopressor or inotropes.

Assessing the Utility of End-Tidal Carbon Dioxide as a Marker for Fluid Responsiveness in Cardiogenic Shock

Background

Preventing end-organ failure in patients with shock requires rapid and easily accessible measurements of fluid responsiveness. Unlike septic shock, not all patients in cardiogenic shock are preload responsive. We conducted this study to determine the discriminant power of changes in end-tidal carbon dioxide (ETCO₂), systolic blood pressure (SBP), inferior vena cava (IVC) collapsibility index (IVC-CI), and venous to arterial carbon dioxide (Pv-aCO₂) gap after a fluid challenge and compared it to increases in cardiac output.

Methodology

In a prospective, quasi-experimental design, mechanically ventilated patients in cardiogenic shock were assessed for fluid responsiveness by comparing improvement in cardiac output (velocity time integral) with changes in ETCO₂, heart rate, SBP, Pv-aCO₂ gap, IVC-CI after a fluid challenge (a crystalloid bolus or passive leg raise).

Results

Out of 60 patients, with mean age 61.3 ± 14.8 years, mean acute physiology and chronic health evaluation (APACHE) score ­14.82 ± 7.49, and median ejection fraction (EF) 25% (25-35), 36.7% (22) had non ST-segment elevation myocardial infarction (NSTEMI) and 60% (36) were ST-segment elevation myocardial infarction (STEMI). ETCO₂ was the best predictor of fluid responsiveness; area under the curve (AUC) 0.705 (95% confidence interval (CI) 0.57-0.83), p=0.007, followed by reduction in Pv-aCO₂ gap; AUC 0.598 (95% CI; 0.45-0.74), p= 0.202. Changes in SBP, mean arterial pressure (MAP), IVC-CI weren’t significant; 0.431 (p=0.367), 0.437 (p=0.410), 0.569 (p=0.367) respectively. The discriminant value identified for ETCO₂ was more than equal to 2 mmHg, with sensitivity 58.6%, specificity 80.7%, positive predictive value 73.9% [95% CI; 56.5% to 86.1%], negative predictive value 69.7% [95% CI; 56.7% to 76.9%].

Conclusions

Change in ETCO₂ is a useful bedside test to predict fluid responsiveness in cardiogenic shock.

Respiratory Variations in Aortic Blood Flow to Predict Volume Responsiveness in Ventilated Children With Leukemia and Neutropenic Septic Shock

OBJECTIVES

To investigate whether respiratory variations in aortic blood flow by echocardiography can accurately predict volume responsiveness in ventilated children with leukemia and neutropenic septic shock.

DESIGN

A prospective study.

SETTING

A 25-bed PICU of a tertiary hospital.

PATIENTS

Mechanically ventilated children with leukemia who had been exposed to anthracyclines and exhibited neutropenic septic shock were enrolled.

INTERVENTIONS

Transthoracic echocardiography was performed to monitor the aortic blood flow before and after fluid administration.

MEASUREMENTS AND MAIN RESULTS

After volume expansion, left ventricular stroke volume increased by greater than or equal to 15% in 16 patients (responders) and less than 15% in 14 patients (nonresponders). The performance of respiratory variation in velocity time integral of aortic blood flow and respiratory variation in peak velocity of aortic blood flow for predicting volume responsiveness, as determined by the area under the receiver operating characteristic curve, was 0.74 (95% CI, 0.55-0.94; p = 0.025) and 0.71 (95% CI, 0.53-0.90; p = 0.048), respectively. Positive end-expiratory pressure was higher in nonresponders than in responders (p = 0.035).

CONCLUSIONS

Respiratory variation in velocity time integral of aortic blood flow and respiratory variation in peak velocity of aortic blood flow derived from transthoracic echocardiography showed only a fair reliability in predicting volume responsiveness in ventilated children with leukemia and neutropenic septic shock.

Proceso de enfermería con modelo bifocal aplicado a paciente con alteración hemodinámica

Enfermería es una disciplina que necesita la aplicación del método científico, el cual se conjunta en el Proceso de Enfermería (PE), para la solución de problemas enfermeros. El PE consiste en un documento escrito que refleja el rol enfermero, que es estructurado, sistemático, dinámico y cíclico, centrado en la persona, orientado a resultados y basado en la evidencia. El objetivo en este trabajo fue aplicar un PE con modelo bifocal a paciente femenino del servicio de Unidad de cuidados intensivos adultos (UCIA) en el Instituto de Seguridad Social del Estado de México y Municipios (ISSEMYM) Tlalnepantla, con la finalidad de coadyuvar a su pronta recuperación y restablecimiento de salud. Se realizó un PE a paciente femenino el 31 de Octubre del 2017, bajo un modelo bifocal de Carpenito, que permite la conjunción del diagnóstico de Enfermería (empleando la taxonomía NANDA) y el problema interdependiente para resolver el problema de salud de la paciente. La elaboración del plan de cuidados fue la interrelación entre las taxonomías NOC (para encontrar resultados) y NIC (para encontrar intervenciones). Se concluye que el modelo bifocal en el PE permite en primer lugar la colaboración con el personal de salud y en segundo revertir de manera gradual el problema de salud de la paciente, favoreciendo su restablecimiento.

Quest for the holy grail: Assessment of echo-derived dynamic parameters as predictors of fluid responsiveness in patients with acute aneurysmal subarachnoid hemorrhage

Background:

Acute aneurysmal subarachnoid hemorrhage (aSAH) is a potentially devastating event often presenting with a plethora of hemodynamic fluctuations requiring meticulous fluid management. The aim of this study was to assess the utility of newer dynamic predictors of fluid responsiveness such as Delta down (DD), superior vena cava collapsibility index (SVCCI), and aortic velocity time integral variability (VTIAoV) in patients with SAH undergoing neurosurgery.

Materials and Methods:

Fifteen individuals with SAH undergoing surgery for intracranial aneurysmal clipping were enrolled in this prospective study. Postinduction, vitals, anesthetic parameters, and the study variables were recorded as the baseline. Following this, patients received a fluid bolus of 10 ml/kg of colloid over 20 min, and measurements were repeated postfluid loading. Continuous variables were expressed as mean ± standard deviation and compared using Student's t-test, with a P < 0.05 considered statistically significant. The predictive ability of variables for fluid responsiveness was determined using Pearson's coefficient analysis (r).

Results:

There were 12 volume responders and 3 nonresponders (NR). DD >5 mm Hg was efficient in differentiating the responders from NR (P < 0.05) with a sensitivity and specificity of 90% and 85%, respectively, with a good predictive ability to identify fluid responders and NR; r = 0.716. SVCCI of >38% was 100% sensitive and 95% specific in detecting the volume status and in differentiating the responders from NR (P < 0.05) and is an excellent predictor of fluid responsive status; r = 0.906. VTIAoV >20% too proved to be a good predictor of fluid responsiveness, with a sensitivity and specificity of 100% and 90%, respectively, with a predictive power; r = 0.732.

Conclusion:

Our study showed that 80% of patients presenting with aSAH for intracranial aneurysm clipping were fluid responders with normal hemodynamic parameters such as heart rate and blood pressure. Among the variables, SVCCI >38% appears to be an excellent predictor followed by VTIAoV >20% and DD >5 mmHg in assessing the fluid status in this population.

[Does fasting influence preload responsiveness in ASA 1 and 2 volunteers?]

INTRODUCTION

Preoperative fasting was long regarded as an important cause of fluid depletion, leading to hemodynamic instability during surgery should replenishment not be promptly instituted. Lately, this traditional point of view has been progressively challenged, and a growing number of authors now propose a more restrictive approach to fluid management, although doubt remains as to the true hemodynamic influence of preoperative fasting.

METHODS

We designed an observational, analytic, prospective, longitudinal study in which 31 ASA 1 and ASA 2 volunteers underwent an echocardiographic examination both before and after a fasting period of at least 6h. Data from both static and dynamic preload indices were obtained on both periods, and subsequently compared.

RESULTS

Static preload indices exhibited a markedly variable behaviour with fasting. Dynamic indices, however, were far more consistent with one another, all pointing in the same direction, i.e., evidencing no statistically significant change with the fasting period. We also analysed the reliability of dynamic indices to respond to known, intentional preload changes. Aortic velocity time integral (VTI) variation with the passive leg raise manoeuvre was the only variable that proved to be sensitive enough to consistently signal the presence of preload variation.

CONCLUSION

Fasting does not appear to cause a change in preload of conscious volunteers nor does it significantly alter their position in the Frank-Starling curve, even with longer fasting times than usually recommended. Transaortic VTI variation with the passive leg raise manoeuvre is the most robust dynamic index (of those studied) to evaluate preload responsiveness in spontaneously breathing patients.

Diastolic dysfunction in the critically ill patient

Left ventricular diastolic dysfunction is a common finding in critically ill patients. It is characterized by a progressive deterioration of the relaxation and the compliance of the left ventricle. Two-dimensional and Doppler echocardiography is a cornerstone in its diagnosis. Acute pulmonary edema associated with hypertensive crisis is the most frequent presentation of diastolic dysfunction critically ill patients. Myocardial ischemia, sepsis and weaning failure from mechanical ventilation also may be associated with diastolic dysfunction. The treatment is based on the reduction of pulmonary congestion and left ventricular filling pressures. Some studies have found a prognostic role of diastolic dysfunction in some diseases such as sepsis. The present review aims to analyze thoroughly the echocardiographic diagnosis and the most frequent scenarios in critically ill patients in whom diastolic dysfunction plays a key role.

Does fasting influence preload responsiveness in ASA 1 and 2 volunteers?

INTRODUCTION

Preoperative fasting was long regarded as an important cause of fluid depletion, leading to hemodynamic instability during surgery should replenishment is not promptly instituted. Lately, this traditional point of view has been progressively challenged, and a growing number of authors now propose a more restrictive approach to fluid management, although doubt remains as to the true hemodynamic influence of preoperative fasting.

METHODS

We designed an observational, analytic, prospective, longitudinal study in which 31 ASA 1 and ASA 2 volunteers underwent an echocardiographic examination both before and after a fasting period of at least 6hours (h). Data from both static and dynamic preload indices were obtained on both periods, and subsequently compared.

RESULTS

Static preload indices exhibited a markedly variable behaviour with fasting. Dynamic indices, however, were far more consistent with one another, all pointing in the same direction, i.e., evidencing no statistically significant change with the fasting period. We also analysed the reliability of dynamic indices to respond to known, intentional preload changes. Aortic velocity time integral (VTI) variation with the passive leg raise manoeuvre was the only variable that proved to be sensitive enough to consistently signal the presence of preload variation.

CONCLUSION

Fasting does not appear to cause a change in preload of conscious volunteers nor does it significantly alter their position in the Frank-Starling curve, even with longer fasting times than usually recommended. Transaortic VTI variation with the passive leg raise manoeuvre is the most robust dynamic index (of those studied) to evaluate preload responsiveness in spontaneously breathing patients.

Hyponatremia in the neurocritical care patient: An approach based on current evidence

In the neurocritical care setting, hyponatremia is the commonest electrolyte disorder, which is associated with significant morbimortality. Cerebral salt wasting and syndrome of inappropriate antidiuretic hormone have been classically described as the 2 most frequent entities responsible of hyponatremia in neurocritical care patients. Nevertheless, to distinguish between both syndromes is usually difficult and useless as volume status is difficult to be determined, underlying pathophysiological mechanisms are still not fully understood, fluid restriction is usually contraindicated in these patients, and the first option in the therapeutic strategy is always the same: 3% hypertonic saline solution. Therefore, we definitively agree with the current concept of "cerebral salt wasting", which means that whatever is the etiology of hyponatremia, initially in neurocritical care patients the treatment will be the same: hypertonic saline solution.

Functional hemodynamic monitoring

Functional hemodynamic monitoring is the assessment of the dynamic interactions of hemodynamic variables in response to a defined perturbation. Recent interest in functional hemodynamic monitoring for the bedside assessment of cardiovascular insufficiency has heightened with the documentation of its accuracy in predicting volume responsiveness using a wide variety of monitoring devices, both invasive and noninvasive, and across multiple patient groups and clinical conditions. However, volume responsiveness, though important, reflects only part of the overall spectrum of functional physiologic variables that can be measured to define the physiologic state and monitor response to therapy.

[Hemodynamic monitoring in the critically patient. Recomendations of the Cardiological Intensive Care and CPR Working Group of the Spanish Society of Intensive Care and Coronary Units]

Hemodynamic monitoring offers valuable information on cardiovascular performance in the critically ill, and has become a fundamental tool in the diagnostic approach and in the therapy guidance of those patients presenting with tissue hypoperfusion. From introduction of the pulmonary artery catheter to the latest less invasive technologies, hemodynamic monitoring has been surrounded by many questions regarding its usefulness and its ultimate impact on patient prognosis. The Cardiological Intensive Care and CPR Working Group (GTCIC-RCP) of the Spanish Society of Intensive Care and Coronary Units (SEMICYUC) has recently impulsed the development of an updating series in hemodynamic monitoring. Now, a final series of recommendations are presented in order to analyze essential issues in hemodynamics, with the purpose of becoming a useful tool for residents and critical care practitioners involved in the daily management of critically ill patients.