Assessment of the conjunctival microcirculation in adult patients with cyanotic congenital heart disease compared to healthy controls.

PURPOSE: Congenital heart disease (CHD) is the most common live birth defect and a proportion of these patients have chronic hypoxia. Chronic hypoxia leads to secondary erythrocytosis resulting in microvascular dysfunction and increased thrombosis risk. The conjunctival microcirculation is easily accessible for imaging and quantitative assessment. It has not previously been studied in adult CHD patients with cyanosis (CCHD). METHODS: We assessed the conjunctival microcirculation and compared CCHD patients and matched healthy controls to determine if there were differences in measured microcirculatory parameters. We acquired images using an iPhone 6s and slit-lamp biomicroscope. Parameters measured included diameter, axial velocity, wall shear rate and blood volume flow. The axial velocity was estimated by applying the 1D + T continuous wavelet transform (CWT). Results are for all vessels as they were not sub-classified into arterioles or venules. RESULTS: 11 CCHD patients and 14 healthy controls were recruited to the study. CCHD patients were markedly more hypoxic compared to the healthy controls (84% vs 98%, p = 0.001). A total of 736 vessels (292 vs 444) were suitable for analysis. Mean microvessel diameter (D) did not significantly differ between the CCHD patients and controls (20.4 ± 2.7 µm vs 20.2 ± 2.6 µm, p = 0.86). Axial velocity (Va) was lower in the CCHD patients (0.47 ± 0.06 mm/s vs 0.53 ± 0.05 mm/s, p = 0.03). Blood volume flow (Q) was lower for CCHD patients (121 ± 30pl/s vs 145 ± 50pl/s, p = 0.65) with the greatest differences observed in vessels >22 µm diameter (216 ± 121pl/s vs 258 ± 154pl/s, p = 0.001). Wall shear rate (WSR) was significantly lower for the CCHD group (153 ± 27 s-1 vs 174 ± 22 s-1, p = 0.04). CONCLUSIONS: This iPhone and slit-lamp combination assessment of conjunctival vessels found lower axial velocity, wall shear rate and in the largest vessel group, lower blood volume flow in chronically hypoxic patients with congenital heart disease. With further study this assessment method may have utility in the evaluation of patients with chronic hypoxia.

In Vivo Transcutaneous Monitoring of Hemoglobin Derivatives Using a Red-Green-Blue Camera-Based Spectral Imaging Technique.

Cyanosis is a pathological condition that is characterized by a bluish discoloration of the skin or mucous membranes. It may result from a number of medical conditions, including disorders of the respiratory system and central nervous system, cardiovascular diseases, peripheral vascular diseases, deep vein thrombosis, and regional ischemia. Cyanosis can also be elicited from methemoglobin. Therefore, a simple, rapid, and simultaneous monitoring of changes in oxygenated hemoglobin and deoxygenated hemoglobin is useful for protective strategies against organ ischemic injury. We previously developed a red-green-blue camera-based spectral imaging method for the measurements of melanin concentration, oxygenated hemoglobin concentration (CHbO), deoxygenated hemoglobin concentration (CHbR), total hemoglobin concentration (CHbT) and tissue oxygen saturation (StO2) in skin tissues. We leveraged this approach in this study and extended it to the simultaneous quantifications of methemoglobin concentration (CmetHb), CHbO, CHbR, and StO2. The aim of the study was to confirm the feasibility of the method to monitor CmetHb, CHbO, CHbR, CHbT, and StO2. We performed in vivo experiments using rat dorsal skin during methemoglobinemia induced by the administration of sodium nitrite (NaNO2) and changing the fraction of inspired oxygen (FiO2), including normoxia, hypoxia, and anoxia. Spectral diffuse reflectance images were estimated from an RGB image by the Wiener estimation method. Multiple regression analysis based on Monte Carlo simulations of light transport was used to estimate CHbO, CHbR, CmetHb, CHbT, and StO2. CmetHb rapidly increased with a half-maximum time of less than 30 min and reached maximal values nearly 60 min after the administration of NaNO2, whereas StO2 dramatically dropped after the administration of NaNO2, indicating the temporary production of methemoglobin and severe hypoxemia during methemoglobinemia. Time courses of CHbT and StO2, while changing the FiO2, coincided with well-known physiological responses to hyperoxia, normoxia, and hypoxia. The results indicated the potential of this method to evaluate changes in skin hemodynamics due to loss of tissue viability and vitality.

Risk of Respiratory Syncytial Virus Infection in Cyanotic Congenital Heart Disease in a Subtropical Area.

OBJECTIVE: To compare the risk of respiratory syncytial virus (RSV)-associated hospitalization and analyze the epidemiology of RSV infection in patients with cyanotic and acyanotic congenital heart disease (CHD), we analyzed the nationwide health insurance database from 2005-2010. STUDY DESIGN: This study included 1050 patients with cyanotic CHD and 7077 patients with acyanotic CHD. Patients with acyanotic CHD were further classified into hemodynamically significant (hs)-acyanotic and non-hs-acyanotic groups according to whether they underwent surgery or took at least 2 anticongestive medications. RESULTS: RSV-associated hospitalization was higher in the cyanotic group than in hs-acyanotic and non-hs-acyanotic groups both before 1 year of age (4.8% vs 2.1% vs 1.5%, P < .001) and between 1 and 2 years of age (0.9% vs 0.56% vs 0.14%, P = .003). The hospitalization duration, intensive care, ventilator support prevalence, hospitalization cost, and mortality rate were significantly higher in the cyanotic group than in the other 2 groups. Logistic regression revealed that cyanotic CHD was the most significant risk factor for the ventilator support and RSV-associated mortality. In both patients with cyanotic and acyanotic CHD, RSV-associated hospitalization rate was higher in patients aged younger than 1 year and in spring and autumn in Taiwan, a subtropical country. CONCLUSIONS: The results show that patients with cyanotic CHD have a higher risk of severe RSV infection than do those with acyanotic CHD. RSV prophylaxis is more important and may reduce costs more for patients with cyanotic CHD.

Hypoxia in the term newborn: part one-cardiopulmonary physiology and assessment.

In this first of a three-part series on hypoxia in the term newborn, the emphasis is on cardiopulmonary adaptation of the newborn. This article includes definitions and features of neonatal hypoxia and reviews structural abnormalities of the heart and great vessels, along with pulmonary hypertension. During the transitional phase from intrauterine to extrauterine life, newborn infants require close monitoring in order to recognize and address abnormalities in adaptation. The evaluation of the hypoxic infant is one of the most common problems for the pediatric clinician; although there are several common causes for newborn cyanosis, myriad disorders spanning all organ systems exist as possibilities etiologies. Knowledge of the breadth of feasible diagnoses and a systematic approach to the assessment of these term newborns are essential for accurate diagnosis, treatment, and referral.

Clinical assessment of infant colour at delivery.

OBJECTIVE: Use of video recordings of newborn infants to determine: (1) if clinicians agreed whether infants were pink; and (2) the pulse oximeter oxygen saturation (Spo(2)) at which infants first looked pink. METHODS: Selected clips from video recordings of infants taken immediately after delivery were shown to medical and nursing staff. The infants received varying degrees of resuscitation (including none) and were monitored with pulse oximetry. The oximeter readings were obscured to observers but known to the investigators. A timer was visible and the sound was inaudible. The observers were asked to indicate whether each infant was pink at the beginning, became pink during the clip, or was never pink. If adjudged to turn pink during the clip, observers recorded the time this occurred and the corresponding Spo(2) was determined. RESULTS: 27 clinicians assessed videos of 20 infants (mean (SD) gestation 31(4) weeks). One infant (5%) was perceived to be pink by all observers. The number of clinicians who thought each of the remaining 19 infants were never pink varied from 1 (4%) to 22 (81%). Observers determined the 10 infants with a maximum Spo(2) >/=95% never pink on 17% (46/270) of occasions. The Spo(2) at which individual infants were perceived to turn pink varied from 10% to 100%. CONCLUSION: Among clinicians observing the same videos there was disagreement about whether newborn infants looked pink with wide variation in the Spo(2) when they were considered to become pink.

Do all infants with apparent life-threatening events need to be admitted?

OBJECTIVE: The goal was to identify criteria that would allow low-risk infants presenting with an apparent life-threatening event to be discharged safely from the emergency department. METHODS: We completed data forms prospectively on all previously healthy patients <12 months of age presenting to the emergency department of an urban tertiary care children's hospital with an apparent life-threatening event over a 3-year period. These patients were then observed for subsequent events, significant interventions, or final diagnoses that would have mandated their admission (eg, sepsis). RESULTS: In our population of 59 infants, all 8 children who met the aforementioned outcome measures, thus requiring admission, either had experienced multiple apparent life-threatening events before presentation or were in their first month of life. In our study group, the high-risk criteria of age of <1 month [corrected] and multiple apparent life-threatening events yielded a negative predictive value of 100% to identify the need for hospital admission. CONCLUSIONS: Our study suggests that >30-day-old infants who have experienced a single apparent life-threatening event may be discharged safely from the hospital, which would decrease admissions by 38%.

Assessment of symptoms and exercise capacity in cyanotic patients with congenital heart disease.

OBJECTIVES: Patients with cyanotic congenital heart disease are generally thought to be limited by hypoxemia. To correlate exercise tolerance to the severity of the cardiac abnormality and to further characterize dyspnea in affected patients, we examined 25 adults with uncorrected cyanotic congenital heart disease. DESIGN AND SETTING: Cohort study at a university hospital. METHODS: Symptom-limited cardiopulmonary exercise testing (CPX) was performed on a treadmill. Expiratory gas was analyzed breath by breath for evaluation of maximal exercise performance, ventilation, and ventilatory efficiency in combination with blood gas analysis during rest and exercise. Symptoms were assessed by the ability index and New York Heart Association class, and the results were compared to 101 healthy volunteers. RESULTS: PaO(2) decreased by 26 +/- 8% (mean +/- SD) with exercise (from 49 +/- 12 to 36 +/- 10 mm Hg), while PaCO(2) was only slightly decreased compared to control subjects. Peak oxygen uptake (O(2)) was significantly reduced when compared to control subjects: 16.7 +/- 6.6 mL/kg/min vs 36.1 +/- 7.7 mL/kg/min. Ventilatory efficiency was markedly impaired at rest (minute ventilation [E]/carbon dioxide output [CO(2)] ratio of 70 +/- 18; control subjects, 53 +/- 11; p < 0.005) and during exercise (E vs CO(2) slope, 58 +/- 31; control subjects, 26 +/- 4; p < 0.005). At rest, ventilatory efficiency was correlated to resting pH and PaO(2), while during exercise it was linked to PaO(2). Ventilatory efficiency during exercise had the strongest correlation with observed symptoms, while hypoxemia and peak O(2) were not significantly associated with symptomatic state. CONCLUSION: CPX in patients with cyanotic congenital heart disease provides helpful parameters that better define the symptomatic state of these patients. The summation of disease-related factors is best reflected by ventilatory efficiency. This parameter offers additional and independent information when compared to peak O(2) and the extent of cyanosis alone.