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Biomedical subjects

M Kluckow

Publications and source records attributed to M Kluckow.

18 recordsLinked to original sources
PubMed2004

Clinical detection of low upper body blood flow in very premature infants using blood pressure, capillary refill time, and central-peripheral temperature difference.

OBJECTIVE: To determine the accuracy of blood pressure (BP), capillary refill time (CRT), and central-peripheral temperature difference (CPTd) for detecting low upper body blood flow in the first day after birth. METHODS: A prospective, two centre cohort study of 128 infants born at < 30 weeks gestation. Invasive BP (n = 108), CRT (n = 128), and CPTd (n = 46) were performed immediately before echocardiographic measurement of superior vena cava (SVC) flow at three, 5-10, and 24 hours after birth. RESULTS: Forty four (34%) infants had low SVC flow (< 41 ml/kg/min) in the first day, 13/122 (11%) at three hours, 39/126 (31%) at 5-10 hours, and 4/119 (3%) at 24 hours. CPTd did not detect infants with low flows. Combining all observations in the first 24 hours, CRT > or = 3 seconds had 55% sensitivity and 81% specificity, mean BP < 30 mm Hg had 59% sensitivity and 77% specificity, and systolic BP < 40 mm Hg had 76% sensitivity and 68% specificity for detecting low SVC flow. Combining a mean BP < 30 mm Hg and/or central CRT > or = 3 seconds increases the sensitivity to 78%. CONCLUSIONS: Low upper body blood flow is common in the first day after birth and strongly associated with peri/intraventricular haemorrhage. BP and CRT are imperfect bedside tests for detecting low blood flow in the first day after birth.

Area Under Curve↗
PubMed2003

Effect of early targeted indomethacin on the ductus arteriosus and blood flow to the upper body and brain in the preterm infant.

OBJECTIVE: To determine if indomethacin given to preterm infants with a large ductus arteriosus (DA) in the first hours of life results in maintained or improved brain and upper body blood (superior vena cava (SVC)) flow. STUDY DESIGN: A randomised, double blind trial of indomethacin v placebo. Echocardiography was performed on 111 infants born at < 30 weeks gestation at 3 and/or 10 hours after birth. Infants were eligible if the DA diameter was > 1.6 mm. Infants were randomised to receive indomethacin 0.2 mg/kg or placebo. Crossover occurred if the DA was still > 1.6 mm. Echocardiography was performed one hour after each treatment. RESULTS: Seventy (63%) infants had a DA > 1.6 mm, with 35 randomised to receive indomethacin and 35 to receive placebo. At one hour there was no difference in DA constriction (indomethacin -20% v placebo -15%), change in SVC flow (-1% v -9%), for right ventricular output (RVO). Two hours after indomethacin, 62 infants had uncontrolled observations, at which time significant ductal constriction had occurred. At this time, infants of > or = 27 weeks gestation had significantly greater increases in SVC flow and RVO than infants of < 27 weeks gestation. Infants with failed ductal constriction had significantly lower initial SVC flow and developed more late grade 3/4 peri/intraventricular haemorrhage (P/IVH). Initial SVC flow, but not ductal constriction, was a significant predictor of late grade 3/4 P/IVH in adjusted analysis. CONCLUSIONS: Indomethacin had minimal effect on ductal constriction and blood flow at one hour compared with placebo. Failure of ductal constriction is associated with low SVC flow and subsequent late severe P/IVH.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Which to measure, systemic or organ blood flow? Middle cerebral artery and superior vena cava flow in very preterm infants.

AIM: To describe, in very preterm babies, postnatal changes in measures of middle cerebral artery (MCA) Doppler variables. To relate these peripheral measures to echocardiographic measures of systemic blood flow and ductal shunting, and to study their relation to subsequent intraventricular haemorrhage (IVH). METHODS: 126 babies born before 30 weeks were studied with serial echocardiography and cerebral and Doppler ultrasound of the MCA at 5, 12, 24, and 48 hours of age. Echocardiographic measures included superior vena cava (SVC) flow and colour Doppler diameter of the ductal shunt. MCA Doppler measures included mean velocity, pulsatility index (PI), and estimated colour Doppler diameter. RESULTS: MCA mean velocity increased whereas the PI decreased significantly over the first 48 hours. Babies with low SVC flow had significantly lower MCA mean velocity and estimated diameter than babies with normal SVC flow. There was no difference in PI. On multivariant analysis, the significant associations with MCA mean velocity were mean blood pressure (MBP), heart rate, SVC flow, and lower calculated vascular resistance. The significant associations with PI were larger ductal diameter and lower mean MBP. The significant associations with MCA diameter were higher SVC flow and lower calculated vascular resistance. After controlling for gestation, there was a highly significant association between lowest SVC flow and subsequent IVH but no association between IVH and lowest MCA mean velocity, estimated diameter, PI, or MBP. CONCLUSIONS: These data are consistent with the speculation that SVC flow is a reflection of cerebral blood flow. Low SVC flow is more strongly associated with subsequent IVH than cerebral artery Doppler measures or MBP.

Blood Flow Velocity↗
PubMed2001

Low systemic blood flow in the preterm infant.

Low systemic blood flow in the first hours after birth of a preterm infant is an often unrecognized complication. Traditional measures of cardiovascular adequacy used in the neonatal intensive care unit such as capillary refill time and blood pressure may not identify this problem. Longitudinal measurement of systemic blood flow demonstrates a falling off of blood flow in the first 6-12 h after birth, often to less than half of normal, before a gradual return to normal values by 24-48 h of age. Identification and appropriate treatment of this reduction in flow may assist in preventing some of the complications of prematurity.

Cardiac Output, Low↗
PubMed2001

Low systemic blood flow and hyperkalemia in preterm infants.

OBJECTIVE: Early low systemic blood flow is common in preterm infants. This study examines the relationship among low flow, renal function, and early changes in blood potassium (K(+)). METHODS: Preterm infants (n = 119) born before 30 weeks' gestational age underwent serial Doppler echocardiographic studies. Superior vena cava flow (SVC flow) was assessed as a measure of upper body systemic blood flow uncorrupted by systemic to pulmonary shunts. Serial whole blood K(+) concentrations on each arterial blood gas sample and urinary output in the first 48 hours were recorded. RESULTS: Most infants had a variable degree of rise in K(+) during the first 24 hours of life. The mean rate of rise was 0.17 mmol/L/h, the mean peak K(+) was 5.54 mmol/L, and the mean time of peak K(+) was 20 hours. The peak K(+) occurred after the lowest measured SVC flow in 84% of infants. A significant positive relationship was found between the lowest measured SVC flow and the mean (r = 0.31, P =.001) and peak (r = 0.31, P =.001) K(+) in the first 24 hours. Low SVC flow at 5 hours best predicted the rate of K(+) rise (r = 0.28, P =.002) and at 12 hours best predicted the peak K(+) concentration (r = 0.47, P <.001). The mean minimum SVC flow in the 17 babies who became hyperkalemic was 29.5 mL/kg/min versus 46.2 mL/kg/min in the 102 infants with normokalemia. Urine output in the first 24 hours was significantly lower in the hyperkalemic infants. A K(+) rate rise exceeding 0.12 mmol/L/h in the first 12 hours predicted low SVC flow with 93% accuracy. CONCLUSIONS: The data are consistent with a role for low systemic blood flow leading to reduced urinary output and subsequent hyperkalemia in preterm infants.

Blood Flow Velocity↗
PubMed2000

Ductal shunting, high pulmonary blood flow, and pulmonary hemorrhage.

OBJECTIVE: To describe the relationship among ductal shunting, estimated pulmonary blood flow, and pulmonary hemorrhage in very preterm infants. STUDY DESIGN: A total of 126 babies born before 30 weeks' gestation (median gestation 27 weeks, range 23 to 29 weeks) underwent echocardiography at 5, 12, 24, and 48 hours of age; measurements included right and left ventricular output, superior vena cava flow, and color Doppler diameter of any ductal shunt. Pulmonary blood flow was derived from the sum of right ventricular output and estimated ductal shunt flow. RESULTS: Twelve (9.5%) babies had a pulmonary hemorrhage at a mean age of 38 hours. Compared with the rest of the cohort, these 12 babies were less likely to have had antenatal steroids (59% vs 90%) and were less mature (26 weeks vs 27 weeks). At the echocardiogram closest to the pulmonary hemorrhage, 11 (92%) of the 12 babies had a significant patent ductus arteriosus >1.6 mm in diameter (median 2 mm, range 0.7 to 2.4 mm), and the median pulmonary blood flow was 326 mL/kg/min (range 210 to 598 mL/kg/min). These measurements were significantly higher than those found in the rest of the cohort in the same period (median duct diameter 0.5 mm [range 0 to 2.9 mm], median pulmonary blood flow 237 mL/kg/min [range 107 to 569 mL/kg/min]). At 5-hour echocardiography the babies with pulmonary hemorrhage had significantly larger diameter ducts but similar pulmonary blood flow. CONCLUSIONS: Pulmonary hemorrhage in preterm babies is associated with significant ductal shunting and high estimated pulmonary blood flow.

Coronary Circulation↗
PubMed2000

Superior vena cava flow in newborn infants: a novel marker of systemic blood flow.

BACKGROUND: Ventricular outputs cannot be used to assess systemic blood flow in preterm infants because they are confounded by shunts through the ductus arteriosus and atrial septum. However, flow measurements in the superior vena cava (SVC) can assess blood returning from the upper body and brain. OBJECTIVES: To describe a Doppler echocardiographic technique that measures blood flow in the SVC, to test its reproducibility, and to establish normal ranges. DESIGN: SVC flow was assessed together with right ventricular output and atrial or ductal shunting. Normal range was established in 14 infants born after 36 weeks' gestation (2 measurements taken in the first 48 hours) and 25 uncomplicated infants born before 30 weeks (4 measurements taken in the first 48 hours). Intra-observer and interobserver variability were tested in 20 preterm infants. RESULTS: In 14 infants born after 36 weeks, median SVC flow rose from 76 ml/kg/min on day 1 to 93 ml/kg/min on day 2; in 25 uncomplicated very preterm infants, it rose from 62 ml/kg/min at 5 hours to 86 ml/kg/min at 48 hours. The lowest SVC flow for the preterm babies rose from 30 ml/kg/min at 5 hours to 46 ml/kg/min by 48 hours. Median intra-observer and interobserver variability were 8. 1% and 14%, respectively. In preterm babies with a closed duct, SVC flow was a mean of 37% of left ventricular output and the two measures correlated significantly. CONCLUSIONS: This technique can assess blood flow from the upper body, including the brain, in the crucial early postnatal period, and might allow more accurate assessment of the status of systemic blood flow and response to treatment.

Blood Flow Velocity↗
PubMed2000

Low superior vena cava flow and intraventricular haemorrhage in preterm infants.

OBJECTIVES: To document the incidence, timing, degree, and associations of systemic hypoperfusion in the preterm infant and to explore the temporal relation between low systemic blood flow and the development of intraventricular haemorrhage (IVH). STUDY DESIGN: 126 babies born before 30 weeks' gestation (mean 27 weeks, mean body weight 991 g) were studied with Doppler echocardiography and cerebral ultrasound at 5, 12, 24, and 48 hours of age. Superior vena cava (SVC) flow was assessed by Doppler echocardiography as the primary measure of systemic blood flow returning from the upper body and brain. Other measures included colour Doppler diameters of ductal and atrial shunts, as well as Doppler assessment of shunt direction and velocity, and right and left ventricular outputs. Upper body vascular resistance was calculated from mean blood pressure and SVC flow. RESULTS: SVC flow below the range recorded in well preterm babies was common in the first 24 hours (48 (38%) babies), becoming significantly less common by 48 hours (6 (5%) babies). These low flows were significantly associated with lower gestation, higher upper body vascular resistance, larger diameter ductal shunts, and higher mean airway pressure. Babies whose mothers had received antihypertensives had significantly higher SVC flow during the first 24 hours. Early IVH was already present in 9 babies at 5 hours of age. Normal SVC flows were seen in these babies except in 3 with IVH, which later extended, who all had SVC flow below the normal range at 5 and/or 12 hours. Eight of these 9 babies were delivered vaginally. Late IVH developed in 18 babies. 13 of 14 babies with grade 2 to 4 IVH had SVC flow below the normal range before development of an IVH. Two of 4 babies with grade 1 IVH also had SVC flow below the normal range before developing IVH, and the other 2 had SVC flow in the low normal range. In all, IVH was first seen after the SVC flow had improved, and the grade of IVH related significantly to the severity and duration of low SVC flow. The 9 babies who had SVC flow below the normal range and did not develop IVH or periventricular leucomalacia were considerably more mature (median gestation 28 v 25 weeks). CONCLUSIONS: Low SVC flow may result from an immature myocardium struggling to adapt to increased extrauterine vascular resistances. Critically low flow occurs when this is compounded by high mean airway pressure and large ductal shunts out of the systemic circulation. Late IVH is strongly associated with these low flow states and occurs as perfusion improves.

Antihypertensive Agents↗
PubMed1999

Prostacyclin concentrations and transitional circulation in preterm infants requiring mechanical ventilation.

AIM: To describe the association between early postnatal prostacyclin concentrations in preterm infants; echocardiographic measurements of ductal diameter and ventricular output and clinical outcomes of intraventricular haemorrhage (IVH) and patent ductus arteriosus (PDA). METHODS: Forty nine preterm infants born before 30 weeks of gestational age (median birthweight 980 g, median gestational age 27 weeks) underwent echocardiographic studies at 5, 12, 24 and 48 hours of postnatal age. Measurements included ventricular outputs and the ductal shunt diameter as a measure of the shunt size. Simultaneous measurements of blood pressures, mean airway pressure and inspired fraction of oxygen (FIO2) were recorded. A blood sample for the prostacyclin metabolite 6-ketoprostaglandin F1-alpha (6KPGF1 alpha) was taken at the 5 and 24 hour echocardiogram. RESULTS: The mean 6KPGF1 alpha concentrations were higher than adult concentrations at 5 (515 pg/ml) and 24 (255 pg/ml) hours. There was no association with gestational age. Raised 6KPGF1 alpha concentrations were related to increased need for mechanical ventilation and severity of respiratory disease. At 5 hours, increased 6KPGF1 alpha concentrations were associated with larger PDA and at 24 hours with larger PDA and higher left ventricular output. Infants with higher 6KPGF1 alpha concentrations were more likely to develop clinically significant PDA. There was no association between early measurements of 6KPGF1 alpha and IVH. CONCLUSIONS: Early postnatal prostacyclin concentrations are markedly raised in preterm infants, particularly in those with more severe lung disease. Raised 6KPGF1 alpha concentrations were associated with an increased ductal diameter and subsequent PDA, but not IVH.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

Emergency cervical suture: the obstetrician's dilemma.

We studied the perinatal mortality and morbidity associated with emergency cervical suture at Royal North Shore Hospital over 7 years. There were 23 patients who had an emergency cervical suture inserted and they were divided into 3 groups for analysis, Group 1: patients with cervical dilatation initially detected on routine 18-20 week ultrasonography and later confirmed on clinical examination, Group 2: cervical dilatation < or = 3 cm and Group 3: cervical dilatation >3 cm at presentation. The median delay in delivery in each group was 6, 5 and 3 weeks respectively. The perioperative membrane rupture rate for emergency suture insertion in this study was 13%. The perinatal mortality rate for each group was 0%, 33% and 43% respectively with an overall rate of 33%. Follow-up at 3-5 years of 9 babies with a birth-weight < or = 1,000 g, revealed that of 6 survivors, 1 had moderate disability and 2 had mild disability. No survivors had severe disability. From the results of our study, emergency cervical suture can prolong gestation and in the absence of prolapsed fetal membranes, the perioperative membrane rupture rate is low. However, it is important to consider that the time gained from emergency cervical suture insertion may convert a previable fetus into an extremely premature infant with the risk of long-term disability.

Emergencies↗
PubMed1998

Range of echocardiographic findings in term neonates with high oxygen requirements.

AIMS: To examine the hypothesis that right to left shunting occurs mainly in the lungs rather than through the fetal channels in neonates. METHODS: Thirty two term babies requiring over 70% oxygen had daily colour Doppler echocardiograms until recovery. Measurements included left ventricular fractional shortening, right and left ventricular outputs, colour and pulsed Doppler ductal and atrial shunting and systolic pulmonary artery pressure (SPAP) derived from ductal shunt or tricuspid incompetence velocities. RESULTS: The babies were retrospectively classified into a respiratory group (n = 19) and a persistent pulmonary hypertension (PPHN) group (n = 13) on the basis of clinical history and radiology. At the initial echocardiogram, just 50% of babies had suprasystemic SPAP. Despite better oxygenation, more of the PPHN group had suprasystemic PAP (85% vs 26%). A correlation between SPAP and Oxygen index (OI) was present only in the respiratory group (r = 0.7). Low ventricular outputs (< 150 ml/kg/min) were common in both groups (53% and 79%). The respiratory group had more closed ducts (47% vs 0%) and those ducts which were patient were more constricted (1.75 mm vs 2.6 mm). Pure right to left ductal shunts were seen in just 15% and pure right to left atrial shunts in just 6% of all babies. The serial echocardiograms showed that SPAP fell and ducts closed well before oxygenation improved. Ventricular outputs increased with age in both groups. CONCLUSIONS: Apart from early on in the sickest babies with a primarily respiratory diagnosis and the babies with primary PPHN, most right to left shunting occurred at an intrapulmonary level.

Asphyxia Neonatorum↗
PubMed1996

Relationship between blood pressure and cardiac output in preterm infants requiring mechanical ventilation.

OBJECTIVE: To assess the contribution of cardiac output in determining the blood pressure of preterm infants and to identify other factors that may be important. METHODS: Sixty-seven preterm infants requiring mechanical ventilation (median birth weight, 1015 gm: median gestational age, 28 weeks) underwent on echocardiographic study at on average age of 19 hours (range, 7 to 31 hours). Measurements taken included left ventricular ejection fraction, left and right ventricular outputs by means of pulsed Doppler and the diameter of both the ductal and atrial shunt jets with the use of color Doppler as a measure of the size of shunt. Simultaneous measurements of intraarterial blood pressures, mean airway pressure, and inspired fraction of oxygen were recorded. RESULTS: After we allowed for the influence of ductal shunting, the correlation between the left ventricular output and mean arterial blood pressure was significant but weak (r = 0.38). There were infants with low blood pressures and normal cardiac outputs, and conversely there were infants with low cardiac outputs and normal blood pressure. The infants with a mean arterial blood pressure of less than 30 mm Hg had a significantly lower gestational age (27 vs 28 weeks), higher mean airway pressure (9.0 vs 7.0 cm H2O), larger ductal diameter (1.6 mm vs 0.7 mm) and a lower systemic vascular resistance (163 vs 184 mm Hg/L per minute per kilogram of body weight). Multilinear regression identified higher mean airway pressure and larger ductal diameter as significant negative influences on mean arterial blood pressure, with higher gestational age and higher left ventricular output as significant positive influences. CONCLUSIONS: Normal blood pressure cannot necessarily be equated with normal systemic now. These data emphasize the importance of other influences, and in particular that of varying systemic vascular resistance, in the determination of blood pressure in preterm infants.

Blood Pressure↗
PubMed1996

Early determinants of right and left ventricular output in ventilated preterm infants.

One hundred and twenty ventilated preterm infants, birthweight < 1500 g, were examined within the first 36 hours with colour Doppler echocardiography, to determine the cardiorespiratory influences on right (RVO) and left ventricular output (LVO). Forty nine of these infants had three further daily scans. Measurements included left ventricular (LV) ejection fraction, Doppler determination of RVO and LVO, and ductal and interatrial shunt direction, velocity and colour Doppler diameter. Infants were grouped by respiratory disease severity: mild, mean FIO2 in first 24 hours < 0.5; moderate/severe, mean FIO2 < 0.5; and fatal, death resulting directly from acute respiratory distress. In the early studies ventricular outputs varied widely (RVO: 62-412 ml/kg/minute, LVO: 75-505 ml/kg/minute). The incidence of low ventricular outputs (< 150 ml/kg/minute) increased with worsening respiratory disease. The incidence of low RVO in the mild group was 19%, in the moderate/severe group 42%, and in the fatal group 85%. More infants had a low RVO than a low LVO, reflecting the impact of ductal shunting. Ductal and atrial shunting was predominantly left to right except in those with fatal respiratory disease. In those studied longitudinally, RVO and LVO increased with age and low outputs were not seen after day 3. Multilinear regression analyses, with RVO as the dependent variable, revealed increasing LVO and atrial shunt diameter as significant positive influences and increasing ductal shunt diameter and mean airway pressure as a significant negative influence. With LVO as the dependent variable, increasing RVO, ductal shunt diameter, and age were significant positive influences and increasing atrial shunt diameter was a significant negative influence. Low ventricular outputs are more common with worsening respiratory disease. Mean airway pressure and ductal shunting are two negative influences on ventricular outputs over which there is some therapeutic control.

Cardiac Output↗
PubMed1996

Early ductal shunting and intraventricular haemorrhage in ventilated preterm infants.

AIM: To establish if there is an association between early cardiovascular adaptation and intraventricular haemorrhage (IVH). METHODS: One hundred and seventeen ventilated preterm infants (mean gestational age 27 weeks, mean birthweight 993 g) were studied echocardiographically within the first 36 hours. Measurements included right (RVO) and left ventricular outputs (LVO), ductus arteriosus (PDA) and atrial shunt diameter using colour Doppler and pulsed Doppler direction and velocity of both shunts. Clinical variables collected over the first 24 hours included use of antenatal steroids, respiratory severity, and mean blood pressure. Cerebral ultrasound scans were reported by a radiologist blinded to clinical and echocardiographic data. RESULTS: Antenatal steroids (two doses) had been given to 73% of the 86 infants with no IVH compared with 48% of the 21 infants with grades 1 and 2 IVH, and just 10% of 10 babies with grades 3 and 4 (P < 0.05). Both groups with IVH had significantly larger PDA diameters than the group with no IVH. Infants with grades 3 and 4 IVH had significantly lower RVO than the other infants. These differences were more pronounced when only infants with definite late IVH were analysed. Logistic regression analysis showed lack of antenatal steroids and larger PDA diameters were significantly associated with any grade of IVH and lack of antenatal steroids; lower RVO was significantly associated with grades 3 and 4 IVH. CONCLUSIONS: Larger early PDA shunts, lower RVO, and lack of antenatal steroids were significantly associated with IVH.

Adrenal Cortex Hormones↗
PubMed1995

Early echocardiographic prediction of symptomatic patent ductus arteriosus in preterm infants undergoing mechanical ventilation.

OBJECTIVE: To identify early echocardiographic markers allowing prediction of subsequent symptomatic patent ductus arteriosus (PDA). METHODS: One hundred sixteen preterm infants ( < 1500 gm) requiring mechanical ventilation underwent echocardiography at a mean postnatal age of 19 hours (range, 7 to 31 hours). Four potential markers were studied: the left atrial to aortic root ratio, pulsed Doppler signal within the course of the duct (ductal diameter), and the direction of postductal aortic diastolic flow. Subsequent ductal closure or significant patency (if suspected clinically) was confirmed echocardiographically. RESULTS: A significant PDA developed in 42 infants (36%). Ductal diameter was the most accurate echocardiographic marker in predicting subsequent significant most accurate echocardiographic marker in predicting subsequent significant PDA. With a ductal diameter of 1.5 mm or greater there were 34 true-positive, 11 false-positive, 63 true-negative, and 8 false-negative results, giving a positive likelihood ratio of 5.5 and a negative likelihood ratio of 0.22 for prediction of development of a PDA requiring treatment. The sensitivity was 81% and the specificity was 85%. Only one infant older than 28 weeks of gestational age had a significant PDA, and limiting the analysis to infants younger than 29 weeks of gestation further improved the predictive accuracy of ductal diameter. The positive likelihood ratio was 8.1 and the negative likelihood ratio was 0.19, with a sensitivity of 83% and a specificity of 90%. CONCLUSION: Color Doppler measurement of the internal ductal diameter allows early prediction of significant PDA in preterm infants.

Ductus Arteriosus↗