Clinicians' abilities to estimate cardiac index in ventilated children and infants

OBJECTIVES—To evaluate the ability of clinicians involved in the provision of paediatric intensive care to estimate cardiac index in ventilated children, based on physical examination and clinical and bedside laboratory data.METHODS—Clinicians were exposed to all available haemodynamic and laboratory data for each patient, allowed to make a physical examination, and asked to first categorise cardiac index as high, high to normal, low to normal, or low, and then to quantify this further with a numerical estimate. Cardiac index was measured simultaneously by femoral artery thermodilution (coefficient of variation 5.37%). One hundred and twelve estimates were made by 27 clinicians on 36 patients (median age 34.5months).RESULTS—Measured cardiac index ranged from 1.39 to 6.84 l/min/m². Overall, there was poor correlation categorically (κ statistic 0.09,weighted κ 0.169) and numerically (r = 0.24, 95% confidence interval 0.06 to 0.41 ), although some variation was seen among the various levels of seniority. CONCLUSION—Assuming that objective measurement, and hence manipulation, of haemodynamic variables may improve outcome, these findings support the need for a safe, accurate, and repeatable technique for measurement of cardiac index in children who are critically ill.     

Functional residual capacity in ventilated infants and children

Positive end expiratory pressure (PEEP) is an accepted treatment for children with acute respiratory failure secondary to restrictive lung diseases. Using a simple technique based on open circuit nitrogen washout, we determined the functional residual capacity (FRC) in 25 ventilated children (age 3 wk-10 y) with acute respiratory failure secondary to restrictive lung disease (pulmonary edema, bilateral pneumonia). FRC measured at a physiologic level of PEEP (2-4 cm H2O) was 45.0 +/- 3.6% (mean +/- SEM; range 12-80%) lower than normal predicted values. At the PEEP level chosen clinically (4-10 cm H2O, mean = 6.0), the FRC was below normal predicted values for nonintubated children by a mean of 31.8% (range 0-73%) (p = 0.0001) and only seven patients (28%) had FRC within 20% below predicted normal values. FRC normalized at PEEP levels of 6-18 cm H2O (mean = 11.6), which was up to 200% above the clinically chosen PEEP level. In six children without lung disease who were ventilated at a PEEP level of 2-4 cm H2O, the FRC was within normal range in two, but significantly higher (by 45%) in the other four. We conclude that FRC in ventilated children with acute restrictive lung disease is significantly lower than normal and the clinically chosen PEEP fails to normalize the FRC in most of the cases.     

Evaluation of a noninvasive cardiac output monitor in mechanically ventilated children.

OBJECTIVE: To compare measurements of cardiac output (CO) and cardiac index (CI) obtained by a recently developed noninvasive continuous cardiac output system, NICO (CONICO), and transthoracic Doppler echocardiography (COTTE) in mechanically ventilated children. DESIGN AND SETTING: Prospective study in a university-affiliated tertiary pediatric intensive care unit. PATIENTS: A total of 21 mechanically ventilated children, weighing >15 kg, in stable respiratory and hemodynamic condition. MEASUREMENTS: Sets of three successive measurements of CO with the NICO system and transthoracic Doppler echocardiography were obtained. Bland-Altman analysis was used to compare the agreement between the two methods. RESULTS: The mean +/- sd CO values were 4.06 +/- 1.43 L/min for CONICO and 4.67 +/- 1.78 L/min for COTTE. Bias +/- sd between the two methods was -0.61 +/- 0.94 L/min. The variability of the difference between the two methods increased as the magnitude of the CO measurement increased. Similar results were obtained for cardiac index: 4.01 +/- 1.40 L.min.m for CINICO and 4.59 +/- 1.48 L.min.m for CITTE. Bland-Altman analysis revealed a nonuniform relationship between CI difference and the magnitude (y = -0.299 - 0.0655 x mean). The variability of the differences did not increase as the magnitude of the CO measurement increased (sd of estimate was 0.827 L.min.m). With both CONICO and CINICO, each measurement was highly repeatable, with coefficient of variation of only 2.88% +/- 2.31%. Repeatability with Doppler echocardiography was 7.02% +/- 4.33%. CONCLUSIONS: The NICO system is a new device that measures CO easily and automatically in mechanically ventilated children weighing >15 kg. CO values obtained with this technique were in agreement with those obtained with Doppler echocardiography in children in respiratory and hemodynamic stable condition. The NICO system needs further investigation in children in unstable respiratory and hemodynamic condition.     

Hemodynamic management in chronically ventilated infants

Positive pressure ventilation can significantly alter hemodynamics. The reduction in systemic venous return and increase in right ventricular afterload in response to an inappropriately high mean airway pressure can decrease pulmonary blood flow and compromise systemic perfusion as a result. In addition to ventilator parameters, the degree of hemodynamic effects depends on the baseline cardiac function and lung compliance. Furthermore, the chronically ventilated infants often have a multitude of comorbidities which may also impact hemodynamics. These include pulmonary and systemic hypertension which can lead to myocardial dysfunction as a result of the increase in the right and left ventricular afterload, respectively. In this section, we aim to outline the hemodynamic changes associated with chronic lung disease and mechanical ventilation and discuss management options.     

Post-extubation atelectasis in ventilated newborn infants

Post-extubation atelectasis (PEA) constitutes the commonest cause of lung collapse in ventilated neonates. The clinical and radiological features of 47 ventilated infants who developed PEA within 24 h of extubation are reported. Three main radiographic patterns of atelectasis were identified: (1) transient unilobar collapse resolving within 12 h of extubation (19 cases), (2) multilobar atelectasis developing over a 48-h period (18 cases), and (3) progressive atelectasis resulting in complete collapse of a whole lung. A similar number of ventilated infants without PEA served as controls. We found a significant association between the incidence of PEA and multiple intubation (P<0.02), presence of patent ductus arteriosus (P<0.001) and neonatal sepsis (P<0.05). Prophylactic physiotherapy is recommended for ventilated infants, particularly those with the above risk factors.Presented at the 29th Congress of the European Society of Pediatric Radiology, 27 April to 1 May 1992, Budapest, Hungary     

Blood pressure responses to care procedures in ventilated preterm infants

Responses of mean aortic blood pressure to sequences of routine care procedures in 22 ventilated, preterm infants were studied daily for the first 3 days of life. In the first 11 infants standard care procedures were used, whereas the next 11 infants were preoxygenated by a preceding 10% increase in inspired oxygen concentration; in these infants, chest physiotherapy was entirely omitted while the frequency of endotracheal suctioning was reduced. A total of 259 blood pressure responses were recorded. In general, responses were biphasic, consisting of an initial blood pressure drop followed by a greater blood pressure rise of longer duration. Baseline blood pressure, as well as the minimum and maximum blood pressure during the care procedures, increased with gestational age and with postnatal age. The blood pressure drop was most pronounced in the infants requiring the most intensive ventilatory support and was reduced by modifying the care procedures. The blood pressure rise was the least in the infants receiving pancuronium and phenobarbitone. Eight infants, 4 in each group, had intraventricular haemorrhage; in these infants, the care procedures induced more pronounced blood pressure drops in the first day of life when compared to the infants without haemorrhage.     

Sudden cardiac death in infants, children, and adolescents

Although SCD is relatively uncommon, its psychosocial impact is devastating. This article has reviewed the potential causes of SCD in infants, children, and adolescents. Many patients who die from SCD have identifiable cardiac disease and are known to have been at risk; however, the existence of other cardiac abnormalities, such as hypertrophic cardiomyopathy or long QT syndrome, may not be known, and SCD may be the first symptom. The authors' contention is that many of the patients in this latter group (e.g., patients who have hypertrophic cardiomyopathy or LQLTS but who have no symptoms) can be screened with a careful, accurate, and detailed history, including family history and review of systems, and physical examination. Any patient with a positive family history, positive review of systems, or positive physical examination should receive further in-depth evaluation, such as an ECG and echocardiogram. These studies permit the detection of most, if not all, of the entities potentially associated with SCD in the pediatric population.     

Preparing families to care for ventilated infants at home

Advances in neonatal care have led to increased survival of infants with complex medical needs and technology dependence. Transition of the ventilator-dependent infant from hospital to home is a complex process that requires extensive coordination between the medical team and family. Home caregivers must be prepared to provide routine care for the ventilator-dependent child and respond to life-threatening emergencies. Families should be counseled on the need for home nursing, medical equipment and an adequate home environment to ensure a safe transition to home. Throughout the process, the family may require financial, social and psychological support. A structured education and transition process that is clearly communicated to parents is necessary to have an effective partnership with families.     

Muscle relaxation in mechanically ventilated infants.

We evaluated the effect of muscle paralysis on gas exchange and incidence of pneumothorax in 35 severely ill infants on mechanical ventilation. Pancuronium (0.1 mg/kg) was given repeatedly until spontaneous respirations ceased in infants with inadequate gas exchange with FIO2 greater than 0.60, or peak inspiratory pressure greater than 30 cm H2O, or who were breathing out of phase with the respirator. Of 27 infants who had an alveolar-arterial oxygen gradient greater than 300 torr before paralysis, AaDO2 improved by greater than 100 torr within one hour of paralysis in only two infants; it worsened in two infants within the same period. By six hours postparalysis, 12 of 27 infants had improved, five of whom had had a worsening AaDO2 before administration of pancuronium. Changes in oxygenation were unrelated to changes in arterial carbon dioxide tension in most infants. Peak transpulmonary pressures after paralysis were lower than during spontaneous breathing, and may explain the low incidence of pneumothorax (3 of 35) during paralysis. Since those who improved could not be distinguished by birth weight, gestational age, or diagnosis, pancuronium might be worthy of trial in a mechanically ventilated infant with severe lung disease who is at risk for pneumothorax.     

婴儿及儿童原发性心脏肿瘤21例临床分析

目的:总结婴儿及儿童原发性心脏肿瘤的临床特点、治疗方法及预后。方法:回顾性分析2010年5月至2018年8月在首都医科大学附属北京安贞医院小儿心脏中心诊断为原发性心脏肿瘤的21例患儿的临床资料,其中男10例,女11例;中位年龄7个月(胎龄26周～15岁,其中6例胎儿期发现),总结21例患儿的临床特点、治疗方法及预后。结...     

Relation of sleep state to hypoxemic episodes in ventilated extremely-low-birth-weight infants

OBJECTIVE: To determine whether hypoxemic episodes in ventilated extremely-low-birth-weight infants correlate with specific behavioral states.Study design: Three-hour video-electroencephalography-polysomnography was performed on 13 ventilated extremely-low-birth-weight infants with mean postconceptional age of 28.3 weeks. The electroencephalogram was scored for discontinuity. Rapid eye movements, body, head, and limb movements were scored from synchronized video. Sleep states were defined from electroencephalography, rapid eye movements, and movement criteria. Nonparametric statistics were used to test for differences in the proportion of time hypoxemic (oxygen saturation 相似文献   

Doppler-derived mean aortic flow velocity in children: An alternative to cardiac index

Summary This study tested the hypothesis that mean aortic velocity is relatively constant in children. Eighty-eight normal children (aged 1 month to 15 years) were studied prospectively. Ascending aortic flow velocities were obtained by pulse Doppler and mean aortic velocities calculated. Mean aortic flow velocity was relatively constant for all ages at 28.4±4.8 cm/s. As Doppler is easy to perform, mean aortic flow velocity may be an alternative approach to the assessment of cardiac output.Presented at the Western Society for Pediatric Research, Carmel, February, 1987.     

Exhaled nitric oxide in chronically ventilated preterm infants

Exhaled nitric oxide (eNO) levels were measured in eight ventilated infants, mean gestational age 25.8 (SD 1.7) weeks and postnatal age 55 (SD 39) days, before and after three days of dexamethasone treatment. The eNO levels fell from a mean of 6.5 (SD 3.4) to 4.2 (SD 2.6) parts per billion (p = 0.031) and the mean supplementary oxygen levels from 62% to 45% (p = 0.0078).     

Aerosol delivery to ventilated newborn infants: historical challenges and new directions

There are several aerosolized drugs which have been used in the treatment of neonatal respiratory illnesses, such as bronchodilators, diuretics, and surfactants. Preclinical in vitro and in vivo studies identified a number of variables that affect aerosol efficiency, including particle size, aerosol flows, nebulizer choice, and placement. Nevertheless, an optimized aerosol drug delivery system for mechanically ventilated infants still does not exist. Increasing interest in this form of drug delivery requires more controlled and focused research of drug/device combinations appropriate for the neonatal population. In the present article, we review the research that has been conducted thus far and discuss the next steps in developing the optimal aerosol delivery system for use in mechanically ventilated neonates.     

Effects of red cell transfusion on cardiac output and perfusion index in preterm infants

Objective/Aim

The present investigation was designed to study the effect of blood transfusion on cardiac output and perfusion index. The aim was to demonstrate a relationship between hematocrit, lactate, cardiac output and perfusion index in anemic preterm infants and to investigate significant changes in these parameters induced by RBC transfusion.

Methods

Anemic infants who were under 35 weeks of gestational age (GA) and were in a stable clinical condition without respiratory or cardiac problems, signs of sepsis, or renal disease at the time of investigation were enrolled in the study. Enrolled infants received 15 ml/kg pure red blood cells over 4 h. Hematocrit and lactate levels were studied before and after transfusion. Cardiac output was measured by an ultrasound device (USCOM 1A) and perfusion index was monitored by pulse oximeter (MasimoRad7).

Results

Cardiac output decreased by 9% (p < 0.05), due to decrease in heart rate by 10% (p < 0.05) and stroke volume significantly by 5% (p < 0.05) both in left and right sided cardiac measurements. Perfusion index significantly increased and lactate levels significantly decreased after transfusion (p < 0.05). Htc was inversely correlated with lactate levels, HR, CI and CO (r = − 0.33, p = 0.01; r = − 0.53, p = 0; r = − 0.37, p = 0.004, r = − 0.28, p = 0.03). PI was not significantly correlated with Htc levels before and after transfusion (r = 0.07, p = 0.7 and r = 0.007, p = 0.97).

Conclusion

Our data support that heart rate, CO and CI and lactate levels increased as a response to anemia in preterm infants and RBC transfusion improved perfusion index suggesting better tissue oxygenation.