Blood pressure in the first year of life in healthy infants born at term

Hemodynamic changes during spinal anesthesia in premature infants with congenital heart disease undergoing inguinal hernia correction

INTRODUCTION

There are conflicting reports on the effects of spinal anesthesia (SA) on hemodynamics. Data on the hemodynamic effects of SA in infants with congenital heart disease (CHD) are limited.

METHODS

We reviewed our experience with 44 unsupplemented SA with 1 mg·kg(-1) of either hyperbaric tetracaine or bupivacaine in premature and former premature infants with noncyanotic CHD. Hemodynamics and oxyhemoglobin saturation (SpO(2)) were assessed. Neither preoperative fluid boluses nor atropine was administered to any of the infants.

RESULTS

There was no significant change in systolic, diastolic, or mean blood pressures from pre-SA induction compared with end of surgery. Heart rate showed a small but systematic decline (mean change of 10 beats per minute, P < 0.01) but was within the normative range values for age. There was a small, but clinically insignificant increase in SpO(2) across the time course. Intraoperatively, two infants developed transient apneic spells. No infant developed postoperative apnea, oxygen desaturation, or bradycardia.

CONCLUSIONS

The data suggest that SA with 1 mg·kg(-1) of either hyperbaric tetracaine or bupivacaine can be used safely as the sole anesthetic for inguinal hernia repair in infants with noncyanotic CHD even when fluid restricted and apparently causes minimal respiratory complications in these infants.

Hypertension in the neonatal period

PURPOSE OF REVIEW

Continued interest in neonatal hypertension has led to generation of new data on normal blood pressure (BP) values in neonates, identification of new causes of hypertension in the neonatal period, and improved insights into therapy.

RECENT FINDINGS

Normal BP in neonates depends on a variety of factors, including gestational age, postnatal age, and birth weight, and may be influenced by other antenatal conditions. The incidence of neonatal hypertension is low, and it is most often seen in infants with concurrent conditions such as chronic lung disease (CLD) or renal disease, or in those that have undergone umbilical arterial catheterization. Although few data exist on efficacy and safety of antihypertensive medications in neonates, a wide variety of medications have been utilized in those who do require treatment. Hypertension resolves over time in most infants, although robust long-term outcome data are lacking.

SUMMARY

Our understanding of neonatal hypertension continues to evolve. Although better data are available on normal BP and the incidence of hypertension, we still need studies focused on appropriate treatment and long-term prognosis.

Hypertension in infancy: diagnosis, management and outcome

Advances in the ability to identify, evaluate, and care for infants with hypertension, coupled with advances in the practice of Neonatology, have led to an increased awareness of hypertension in modern neonatal intensive care units. This review will present updated data on blood pressure values in neonates, with a focus on the changes that occur over the first days and weeks of life in both term and preterm infants. Optimal blood pressure measurement techniques as well as the differential diagnosis of hypertension in the neonate and older infants will be discussed. Recommendations for the optimal immediate and long-term evaluation and treatment, including potential treatment parameters, will be presented. We will also review additional information on outcome that has become available over the past decade.

Flow visualization of a pediatric ventricular assist device during stroke volume reductions related to weaning

The aim of this study is to define the fluid mechanics of a pulsatile pneumatically driven pediatric ventricular assist device (PVAD), for the reduced flow rates encountered during device weaning and myocardial recovery, and relate the results to the potential for thromboembolic events. We place an acrylic model of the PVAD in a mock circulatory loop filled with a viscoelastic blood analog and operate at four stroke volumes (SVs), each with two different filling conditions, to mimic how the flow rate of the device may be reduced. Particle image velocimetry is used to acquire flow field data. We find that a SV reduction method provides better rotational flow and higher wall shear rates than a beat rate reduction method; that a quick filling condition with a compressed diastolic time is better than a slow filling condition; and, that a reduction in SV to 40% led to greatly reduced fluid movement and wall shear rates that could increase the thrombogenicity of the device. SV reduction is a viable option for flow reduction during weaning, however, it does lead to significant changes to the device flow field and future studies are needed to develop operational protocols for the PVAD during bridge-to-recovery.

Efficacy and safety of propranolol as first-line treatment for infantile hemangiomas

Beta-blockers are a highly promising treatment modality for complicated infantile hemangiomas (IH). However, data on propranolol as first-line treatment, objective outcome measures and impact on hemodynamics in young infants is limited. We retrospectively evaluated a homogenous group of infants with proliferating complicated IH treated with propranolol (2 mg/kg/day). Outcome was assessed by blinded evaluation of clinical photographs by visual analogue scale (VAS), ultrasound examination and ophthalmological review (if appropriate). Tolerance and hemodynamic variables were recorded over time, including a 2-day in-patient observation at the initiation of therapy. Twenty-five infants (median age 3.6 (1.5-9.1) months) were included in the study. The median follow-up-time was 14 (9-20) months and 14 patients completed treatment at a median age of 14.3 (11.4-22.1) months, after a duration of 10.5 (7.5-16) months. In all patients, there was significant fading of colour (with a VAS of -9 (-6 to -9) after 7 months) and significant decrease in size of the IH (with a VAS of -8 (-3 to -10) after 7 months). Median thickness of the lesions assessed by ultrasound at baseline and after 1 month was 14 (7-28) mm and 10 (5-23) mm, respectively (p < 0.01). In children with periocular involvement, astigmatism and amblyopia resolved rapidly within 8 weeks. The overall tolerance of propranolol was good, and no relevant hemodynamic changes were noted.

CONCLUSION

Our report supports the excellent effect and good tolerance of this novel therapy, and we propose the use of propranolol as first-line treatment for IH.

Hemodynamics of an end-to-side anastomotic graft for a pulsatile pediatric ventricular assist device

Numerical simulations are performed to investigate the flow within the end-to-side proximal anastomosis of a pulsatile pediatric ventricular assist device (PVAD) to an aorta. The anastomotic model is constructed from a patient-specific pediatric aorta. The three great vessels originating from the aortic arch--brachiocephalic (innominate), left common carotid, and left subclavian arteries--are included. An implicit large eddy simulation method based on a finite volume approach is used to study the resulting turbulent flow. A resistance boundary condition is applied at each branch outlet to study flow splitting. The PVAD anastomosis is found to alter the aortic flow dramatically. More flow is diverted into the great vessels with the PVAD support. Turbulence is found in the jet impingement area at peak systole for 100% bypass, and a maximum principal normal Reynolds stress of 7081 dyn/cm(2) is estimated based on ten flow cycles. This may be high enough to cause hemolysis and platelet activation. Regions prone to intimal hyperplasia are identified by combining the time-averaged wall shear stress and oscillatory shear index. These regions are found to vary, depending on the percentage of the flow bypass.

Comparative Study of Continuous and Pulsatile Left Ventricular Assist Devices on Hemodynamics of a Pediatric End-to-Side Anastomotic Graft

Although there are many studies that focus on understanding the consequence of pumping mode (continuous vs. pulsatile) associated with ventricular assist devices (VADs) on pediatric vascular pulsatility, the impact on local hemodynamics has been largely ignored. Hence, we compare not only the hemodynamic parameters indicative of pulsatility but also the local flow fields in the aorta and the great vessels originating from the aortic arch. A physiologic graft anastomotic model is constructed based on a pediatric, patient specific, aorta with a graft attached on the ascending aorta. The flow is simulated using a previously validated second-order accurate Navier-Stokes flow solver based upon a finite volume approach. The major findings are: (1) pulsatile support provides a greater degree of vascular pulsatility when compared to continuous support, which, however, is still 20% less than pulsatility in the healthy aorta; (2) pulsatile support increases the flow in the great vessels, while continuous support decreases it; (3) complete VAD support results in turbulence in the aorta, with maximum principal Reynolds stresses for pulsatile support and continuous support of 7081 and 249 dyn/cm2, respectively; (4) complete pulsatile support results in a significant increase in predicted hemolysis in the aorta; and (5) pulsatile support causes both higher time-averaged wall shear stresses (WSS) and oscillatory shear indices (OSI) in the aorta than does continuous support. These findings will help to identify the risk of graft failure for pediatric patients with pulsatile and continuous VADs.

Clinical analysis of hypertension in children admitted to the emergency department

BACKGROUND

Hypertension in children is a relatively rare disease and has a high risk of further severe damage. The current study aimed to survey the clinical spectrum of hypertension in children admitted to an emergency department (ED).

METHODS

We reviewed the medical records of all children aged 18 years and younger in whom a diagnosis of hypertension was made at the ED in Changhua Christian Hospital between 1998 and 2008. The patients were divided into four age groups (infants, preschool-age, school-age and adolescents) and three severity levels (transient hypertension, hypertension and hypertensive crisis). Case distribution analysis of hypertension based on different months and years was performed. Body mass index, blood pressure, etiologies and presenting symptoms were also analyzed according to age groups and severity levels.

RESULTS

A total of 99 children met the inclusion criteria and were included in the current study. Diagnoses included 15 transient hypertension (15.1%), 28 hypertension (28.3%) and 56 hypertensive crises (56.6%). Almost all of the hypertensive crisis patients presented with stage 2 hypertension (n = 55, 98.2%). Dizziness and headache were the most common presenting symptom in patients in school-age and adolescent groups. Of the symptoms described, altered mental status and coma were most common in preschool-age and school-age groups. Neurologic disorder (26.3%) was the most common etiology in children younger than 6 years of age, followed by renal disorders (21.0%). In children older than 6 years of age, the major etiologies of hypertension and hypertensive crisis included untreated primary hypertension, renal disorders and endocrine disorders.

CONCLUSION

Hypertension in children may be easily underestimated but is potentially life-threatening in the pediatric ED. Primary care clinicians should promptly identify patients with stage 2 hypertension and treat them immediately and appropriately to prevent damage to cardiovascular organs.

The many facets of the matricelluar protein periostin during cardiac development, remodeling, and pathophysiology

Periostin is a member of a growing family of matricellular proteins, defined by their ability to interact with components of the extracellular milieu, and with receptors at the cell surface. Through these interactions, periostin has been shown to play a crucial role as a profibrogenic molecule during tissue morphogenesis. Tissues destined to become fibrous structures are dependent on cooperative interactions between periostin and its binding partners, whereas in its absence, these structures either totally or partially fail to become mature fibrous entities. Within the heart, fibrogenic differentiation is required for normal tissue maturation, remodeling and function, as well as in response to a pathological myocardial insult. In this review, aspects related to the function of periostin during cardiac morphogenesis, remodeling and pathology are summarized.

Arginine vasopressin to manage hypoxemic infants after stage I palliation of single ventricle lesions

OBJECTIVE

Management of patients with single ventricle physiology following stage I palliation procedures is often challenging, with optimization of the ratio of pulmonary-to-systemic blood flow as an important goal. Persistent hypoxemia may be a manifestation of elevated pulmonary vascular resistance and therefore decreased blood flow to the lungs. In such situations, the use of arginine vasopressin to increase systemic vascular resistance may be an effective strategy to improve pulmonary blood flow and maintain adequate pulmonary-to-systemic blood flow ratio. We describe three infants in whom persistent hypoxemia improved after institution of arginine vasopressin.

DESIGN

Retrospective chart review.

SETTING

Twenty-four bed medical-surgical pediatric intensive care unit at a large tertiary care academic hospital.

PATIENTS

Three neonates with single ventricle physiology who received arginine vasopressin in the setting of hypoxemia following stage I palliation.

RESULTS

Arginine vasopressin was initiated in all three patients for hypoxemia with a goal to increase systemic vascular resistance and generate a higher driving pressure for pulmonary blood flow. Twelve hours after arginine vasopressin initiation, systemic arterial saturation as determined by pulse oximetry and blood pressure increased, whereas heart rate, inotrope score, and Fio2 decreased in all three patients. Urine output was maintained and arterial lactate decreased during this time. Pulmonary-to-systemic flow ratio increased in one patient in whom it could be determined.

CONCLUSION

In patients with single ventricle physiology and persistent hypoxemia following stage I palliation, administration of arginine vasopressin could improve oxygenation possibly by increasing systemic vascular resistance and therefore the pulmonary blood flow.