Dr Margaret Harris

We conducted a cross-sectional study of Indigenous youths residing in the Torres Strait region of Australia to assess the prevalence of obesity and the metabolic syndrome. Data on body mass index (BMI), waist circumference, blood pressure, presence of acanthosis nigricans and blood glucose were collected. Fasting glucose, insulin, C-Peptide, HbA1c and lipids were measured, and an oral glucose tolerance test was performed in those with a BMI greater than 25 (childhood-equivalent cut-points) or fasting glucometer reading >5.5 mmol/L. Of 158 youths, 31% were overweight and 15% were obese, 38% had enlarged waist circumference consistent with central obesity, 43% had acanthosis nigricans and 27% were hypertensive. More females than males had enlarged waist circumferences (59% vs. 13%, P < 0.001). Among overweight or obese youth, 56% had significantly elevated insulin (P = 0.021); they also had higher HOMA-IR (P = 0.002). The metabolic syndrome was present in 17% of all youths (mostly females) and in 33% of the overweight or obese subgroup. Type 2 diabetes was diagnosed in two youths. These very high proportions of overweight or obese Torres Strait youth with metabolic risk factors have major public health implications. © 2008 International Association for the Study of Obesity.

¿ Chronic neonatal lung disease (CNLD) is defined as a supplemental oxygen requirement beyond 36 weeks' postmenstrual age, with more severely affected infants requiring oxygen beyond a full-term-equivalent age. ¿ Low-flow supplemental oxygen facilitates discharge from hospital of infants with CNLD who develop hypoxia in air. ¿ There is a lack of data on the most appropriate minimum mean target oxygen saturation (SpO2) level. Reflecting a variety of clinical practices and infant comorbidities (frequency of oxygen desaturation, presence of pulmonary hypertension, retinopathy of prematurity, and adequacy of growth), the minimum mean target range for SpO2 during overnight oximetry should be 93%-95%. ¿ The effect of supplemental oxygen on carbon dioxide retention should be considered before deciding on an oxygen flow. ¿ Most infants with CNLD are not ready for discharge until their supplemental oxygen requirement is = 0.5 litres per minute delivered through a nasal cannula. ¿ The safety of short-term disconnection from supplemental oxygen should be assessed before discharge. ¿ Assessment of oxygenation during sleep with continuous overnight oximetry or polysomnography is recommended when weaning infants from supplemental oxygen. ¿ Discontinuation of oxygen therapy is based on clinical assessments and documentation of adequate oxygenation in room air. ¿ There is limited objective evidence on which to base recommendations.

Conventional overnight polysomnography (PSG) used to determine the respiratory behaviour during sleep can be a complex and expensive procedure. Pulse transit time analysis (PTT) has shown potential to detect obstructive apnoeic and hypopnoeic events (OE) in adults. Due to abnormalities in central ventilatory control, recurring OE may occur. This study was undertaken to determine the potential of PTT to differentiate responses during upper airway obstruction in the paediatric population. This preliminary study included 11 children (10 male; aged 7.5 ± 3.8 year) recruited to investigate PTT trend during single and recurrent OE. PTT measurements were evaluated against the corresponding PSG results pre-scored by two blinded obsercvers. A total of 110 valid OE (47 single and 63 recurrent) were observed during these PSG studies. There were distinct PTT responses observed for these two types of OE with respect to those of tidal breathing (P < 0.05). For the tidal breathing events, the mean absolute standard deviation (SD) and maximal percentage (%) decrease (MAX) were 7.71 ms and 3.88% respectively. For the recurrent OE, the absolute SD, SD (%) and MAX were 52.21 ms, 8.52% and 55.08% accordingly while for the single OE, the absolute SD, SD (%) and MAX were 12.23 ms, 5.27% and 13.56% respectively. The findings herein can suggest that PTT can be a valuable clinical tool in the paediatric respiratory sleep studies. © Springer Science+Business Media, LLC 2008.

Characteristics obtained from peripheral pulses can be used to assess the status of cardiovascular system of subjects. However, nonintrusive techniques are preferred when prolonged monitoring is required for their comfort. Pulse transit time (PTT) measurement has showed its potentials to monitor timing changes in peripheral pulse in cardiovascular and respiratory studies. In children, the common peripheries used for these studies are fingers or toes. Presently, there is no known study conducted on children to investigate the possible physiologic parameters that can confound PTT measure at these sites. In this study, PTT values from both peripheral sites were recorded from 55 healthy Caucasian children (39 male) with mean age of 8.4±2.3 years (range 5-12 years). Peripheries' path length, heart rate, systolic blood pressure, diastolic blood pressure (DBP) and mean arterial pressure (MAP) were measured to investigate their contributions to PTT measurement. The results reveal that PTT is significantly related to all parameters (P<0.05), except for DBP and MAP. Age is observed to be the dominant factor that affects PTT at both peripheries in a child. Regression equations for PTT were derived for measuring from a finger and toe, (6.09 age + 189.2) ms and (6.70 age + 243.0) ms, respectively. © 2005 Nature Publishing Group. All rights reserved.

Pulse oximetry is commonly used as an arterial blood oxygen saturation (SaO2) measure. However, its other serial output, the photoplethysmography (PPG) signal, is not as well studied. Raw PPG signals can be used to estimate cardiovascular measures like pulse transit time (PTT) and possibly heart rate (HR). These timing-related measurements are heavily dependent on the minimal variability in phase delay of the PPG signals. Masimo SET® Rad-9¿ and Novametrix Oxypleth oximeters were investigated for their PPG phase characteristics on nine healthy adults. To facilitate comparison, PPG signals were acquired from fingers on the same hand in a random fashion. Results showed that mean PTT variations acquired from the Masimo oximeter (37.89 ms) were much greater than the Novametrix (5.66 ms). Documented evidence suggests that 1 ms variation in PTT is equivalent to 1 mmHg change in blood pressure. Moreover, the PTT trend derived from the Masimo oximeter can be mistaken as obstructive sleep apnoeas based on the known criteria. HR comparison was evaluated against estimates attained from an electrocardiogram (ECG). Novametrix differed from ECG by 0.71 ± 0.58% (p < 0.05) while Masimo differed by 4.51 ± 3.66% (p > 0.05). Modern oximeters can be attractive for their improved SaO2 measurement. However, using raw PPG signals obtained directly from these oximeters for timing-related measurements warrants further investigations. © 2005 IOP Publishing Ltd.

Studies have shown that increased arterial stiffening can be an indication of cardiovascular diseases like hypertension. In clinical practice, this can be detected by measuring the blood pressure (BP) using a sphygmomanometer but it cannot be used for prolonged monitoring. It has been established that pulse wave velocity (PWV) is a direct measure of arterial stiffening but its usefulness is hampered by the absence of non-invasive techniques to estimate it. Pulse transit time (PTT) is a simple and non-invasive method derived from PWV. However, limited knowledge of PTT in children is found in the present literature. The aims of this study are to identify independent variables that confound PTT measure and describe PTT regression equations for healthy children. Therefore, PTT reference values are formulated for future pathological studies. Fifty-five Caucasian children (39 male) aged 8.4 ± 2.3 yr (range 5-12 yr) were recruited. Predictive equations for PTT were obtained by multiple regressions with age, vascular path length, BP indexes and heart rate. These derived equations were compared in their PWV equivalent against two previously reported equations and significant agreement was obtained (p < 0.05). Findings herein also suggested that PTT can be useful as a continuous surrogate BP monitor in children. © 2005 IOP Publishing Ltd.

Motion artefact is a common occurrence that contaminates photoplethysmographic (PPG) measurements. To extract timing information from signals during artefact is challenging. PPG signal is very sensitive to artefacts and can be used in applications like, pulse transit time (PTT) as part of the polysomnographic studies. A correlation cancellation or signal processing approach is implemented with the adaptive cancelling filter concept and a triaxial accelerometry. PPG signals obtained from a Masimo (Reference) pulse oximeter is used as reference to compare with the reconstructed PPG signals. Different hands are used for each PPG source, one stationary while the other involves typical movements during sleep. A second Masimo pulse oximeter is used to register intensity of timing errors on commercial PPG signals. 108 PTT measurements are recorded in three different movements with PTT estimates from unprocessed PPG signals showing 35.51±27.42%, Masimo 50.02±29.40% and reconstructed 4.32±3.59% difference against those from the Reference PPG. The triaxial accelerometry can be used to detect the presence of artefact on PPG signals. This is useful in PTT measurements when signal contaminated with artefacts are required for further analysis, especially after and during arousals in sleep. The suggested filtering model can then reconstruct these corrupted PPG signals. Copyright © 2004 ACPSEM/EA.

OBJECTIVE: Cystic fibrosis-related diabetes mellitus (CFRD) is an increasingly common complication of cystic fibrosis. CFRD is preceded by a progressive decline in insulin secretion but there is no accepted definition of the prediabetic state in CFRD. This pre-diabetic state appears to have adverse effects on clinical status, nutrition and lung function, but there is no direct evidence that the impaired glucose homeostasis is the cause of these deteriorations. This study examined the prevalence of glucose intolerance and impaired insulin secretion in a population of children with CF without CFRD. Severe CF lung disease is often associated with poor weight gain and slower growth but the mechanism for this is still unclear. The relationships between the current state of glucose homeo-stasis, insulin secretion and the insulin-like growth factor axis, height velocity, nutrition status and lung function were therefore studied. DESIGN AND PATIENTS: Eighteen children with cystic fibrosis aged 9.5-15 years had oral glucose tolerance tests and 14 of these also had intravenous glucose tolerance tests (four refused). Blood samples were collected for insulin, C-peptide, glucose, HbA1c, insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein (IGFBP)-1 and IGFBP-3. Data on height, weight, puberty status, clinical score (Shwachman score) and lung function were recorded. Height velocity, height and weight standard deviation scores (SDS) were calculated using WHO/CDC data. RESULTS: The mean height SDS (-0.52 ± 0.17) was less than the normal population (P = 0.007 and the mean height velocity was 4.6 ± 0.5 cm/year, 39% with a height velocity less than the third percentile for age. The weight SDS and body mass index (BMI) were similar to the normal population. Four children had impaired glucose tolerance. The first-phase insulin response (FPIR) was below the first percentile of normal population values in nine (65%). Impaired FPIR or impaired glucose tolerance did not correlate with the Shwachman score, nutritional status or pulmonary function. There was a significant positive correlation between insulin secretion (area under the curve) and height velocity (P = 0.001) and serum IGFBP-3 levels (P = 0.001). CONCLUSIONS: Impaired glucose tolerance was present in 20% of children with cystic fibrosis. Impaired insulin secretion was common (65%) even in children with normal glucose tolerance. The mean height SDS for the group was low and the height velocity was abnormally slow in 39%, yet nutritional status as measured by BMI was appropriate for age. Relative insulin deficiency rather than nutritional deprivation or poor clinical status thus appears to be implicated in the poor linear growth of these children with relatively stable lung disease. This was a small study and firm conclusions on this chronic suppurative disease as to the cause of poor growth are not possible. The causes of poor growth are likely to be complex; nevertheless, the apparent decrease in insulin secretion combined with the expected increased demands on insulin production during pubertal growth raises the question as to whether insulin therapy should be considered in children with cystic fibrosis before the onset of cystic fibrosis-related diabetes mellitus.

Objective-To survey screening practices, knowledge, and attitudes towards screening among first degree relatives of people with colon cancer. Setting-A random sample of people with colon cancer listed on the New South Wales (NSW) Cancer Registry were mailed a questionnaire to be passed on to an appropriate first degree relative. Methods-Two hundred and twenty five first degree relatives completed a self administered questionnaire. Results- Although there were high levels of awareness about colorectal cancer, and attitudes towards colorectal cancer were generally positive, screening rates were low, and only three relatives had been screened in accordance with current Australian recommendations. Factors associated with previous participation in any type of screening test (usually once) included receiving a medical recommendation to screen, having more than one relative with colorectal cancer, being a sibling of the relative with colon cancer, the relative with cancer being female, and perceiving screening as messy, but not painful. Conclusions-Strategies to enhance screening awareness and participation among relatives need to be considered. This study provides some insight into factors to be considered in developing awareness programmes. Further research is required to explore these factors, and to identify ways to overcome barriers.

Abstract Ceftriaxone as a single daily intravenous dose for 5 days was used to treat seven patients with proven Haemophilus influenzae epiglottitis. All children responded favourably. The serum levels achieved exceeded the MIC by up to 1500 times at the trough level during and for up to 24 h after the completion of the treatment. Side effects were mild and transient and did not disrupt the continuity of the treatment. Ceftriaxone potentially offers a number of clinical and economic advantages in the management of epiglottitis. Copyright © 1992, Wiley Blackwell. All rights reserved

Abstract Accurate delivery of low flow oxygen is essential for the management of infants with chronic respiratory failure. Twenty-seven examples of one low flow oxygen meter were tested. Measured flows were found to differ greatly from indicated settings, particularly at 250 mL/min settings. Knowledge of such errors as well as improved quality control are essential for appropriate management of oxygen therapy. Copyright © 1989, Wiley Blackwell. All rights reserved

Spermophilus columbianus were studied in SW Alberta. Most amicable interactions occurred before females bred; thereafter, most interactions were agonistic. Males chased females more often than they were chased by them before females bred, but thereafter the opposite was true, until about the time juveniles first emerged from natal burrows. This relative dominance by females after breeding was more pronounced in interactions with subordinate males versus dominant, territorial males, with neighboring males versus resident males, and within a female's core area of activity and close to her nest burrow versus outside the core area and more distant from her nest burrow. Lactating females showed greater dominance than those not lactating, especially late in the lactation period. -from Authors

Threespine stickleback, Gasterosteus aculeatus, are thought to have been introduced into Hasse Lake, Alberta, where they were discovered in 1980. The population has grown in numbers since 1980 and by 1981 was more abundant than the native brook stickleback, Culaea inconstans. This population is the first to be found in the interior plains of North America, and it occurs at a higher elevation than any other Canadian population. The source of this introduced population is unknown. Significant differences among four years were found in several meristic and morphometric characters but no significant trends during 1980-1983 were found. Most characters were well within the range of other populations of the species. © 1987 Dr W. Junk Publishers.

The prevalence of sudden infant death syndrome (SIDS) has been well studied and central sleep apnea is deemed as one of the possible causes. Current gold standard for its diagnosis is nocturnal polysomnography (PSG). However, this procedure is complex and generally needs to be performed in a sleep laboratory. Pulse transit time (PTT) shows its potential to indicate abrupt blood pressure (BP) changes during the occurrences of upper airway obstruction. The main objective of this study was to assess the capability of PTT to differentiate central respiratory events from tidal breathing in infants. This study involved 5 infants (4 male) with mean age of 7.8 months. 50 valid central respiratory events were randomly selected. These events were free from motion artifacts and pre-scored in the corresponding PSG studies by two blinded observers. PTT measurements from these events were then evaluated against the PSG scorings. Using a two-tailed F-test for variance, it was observed that central events differed from tidal breathing in a significant manner (p<0.05). Furthermore, PTT has showed its sensitivity to monitor marginal BP fluctuations during tidal breathing. Hence, the results herein suggest that PTT can be a valuable non-invasive technique to monitor central apneic events in sleeping infants. © 2005 IEEE.

Pulse transit time (PTT) is a non-invasive measure, defined as time taken for the pulse pressure waves to travel from the R-wave of electrocardiogram to a selected peripheral site. Baseline PTT value is known to be influenced by physiologic variables like heart rate (HR), blood pressure (BP) and arterial compliance (AC). However, few quantitative data are available describing the factors which can influence PTT measurements in a child during breathing. The aim of this study was to investigate the effects of changes in breathing efforts on PTT baseline and fluctuations. Two different inspiratory resistive loading (IRL) devices were used to simulate loaded breathing in order to induce these effects. It is known that HR can influence the normative PTT value however the effect of HR variability (HRV) is not well-studied. Two groups of 3 healthy children (=12years) were recruited; one group with insignificant (p<0.05) HR changes during all test activities. Results showed that HRV is not the sole contributor to PTT variations and suggest that changes in other physiologic parameters are also equally important. Hence, monitoring PTT measurement can be indicative of these associated changes during tidal or increased breathing efforts in healthy children. © 2005 IEEE.

Studies have shown that an increase in arterial stiffening can indicate the presence of cardiovascular diseases like hypertension. Current gold standard in clinical practice is by measuring the blood pressure of patients using a mercury sphygmomanometer. However, the nature of this technique is not suitable for prolonged monitoring. It has been established that pulse wave velocity is a direct measure of arterial stiffening. However, its usefulness is hampered by the absence of techniques to estimate it non-invasively. Pulse transit time (PTT) is a simple and non-intrusive method derived from pulse wave velocity. It has shown its capability in childhood respiratory sleep studies. Recently, regression equations that can predict PTT values for healthy Caucasian children were formulated. However, its usefulness to identify hypertensive children based on mean PTT values has not been investigated. This was a continual study where 3 more Caucasian male children with known clinical hypertension were recruited. Results indicated that the PTT predictive equations are able to identify hypertensive children from their normal counterparts in a significant manner (p<0.05). Hence, PTT can be a useful diagnostic tool in identifying hypertension in children and shows potential to be a non-invasive continual monitor for arterial stiffening. © 2005 IEEE.

Pulse Transit Time (PTT) measurement has showed potential in non-invasive monitoring of changes in blood pressure. In children, the common peripheral sites used for these studies are a finger or toe. Presently, there are no known studies conducted to investigate any possible physiologic parameters affecting PTT measurement at these sites for children. In this study, PTT values of both peripheral sites were recorded from 64 children in their sitting posture. Their mean age with standard deviation (SD) was 8.2 ± 2.6years (ranged 3 to 12years). Subjects' peripheries path length, heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP) were measured to investigate any contributions to PTT measurement. The peripheral pulse timing characteristic measured by photoplethysmography (PPG) shows a 59.5 ± 8.5ms (or 24.8 ± 0.4%) difference between the two peripheries (p<0.05). The results also revealed PTT is directly proportional to age (p<0.05). HR, SBP, peripheral path length and peripheral site also contributed significantly (p<0.05) to PTT variations, except for DBP. Results also suggest an upward trend in PTT with age. Hence, changes in any of these physiologic parameters can affect the nominal PTT value of a child.

Since its introduction, pulse oximetry has become a conventional clinical measure. Besides being arterial blood oxygen saturation (SpO2) measure, pulse oximeters can be used for other cardiovascular measurements, like heart rate (HR) estimations, derived from its photoplethysmographic (PPG) signals. The temporal coherence of the PPG signals and thereby HR estimates are heavily dependent on its minimal phase variability. A Masimo SET® Rad-9¿, Novametrix Oxypleth and a custom-designed PPG system were investigated for their relative phase variation. R-R intervals from electro-cardiogram (ECG) were recorded concurrently as reference. PPG signals obtained from the 3 systems were evaluated by comparing their respective beat-to-beat (B-B) intervals with the corresponding R-R estimates during a static test. For their relative B-B comparison to the ECG, Novametrix system differed 0.68±0.52% (p<0.05) and custom device 0.89±0.71% (p<.05) while Masimo device 4.17±3.51% (p>0.05). Recent advanced signal processing approach is attractive with respect to the accuracy and noise immunity of the SpO2 measure. However, one consequence may be the variability it induces to the phase coherence of its PPG signal. Clinical interpretation of other measures such as HR may be compromised by these techniques.

Pulse transit time (PTT) is a non-invasive measure and has shown potential to estimate breathing effort variations in response to involuntarily changes of the upper airway in adults during sleep. The objectives of this study were to assess the capability of PTT to classify respiratory sleep events as either central or obstructive in nature and its sensitivity to detect both apnoeas and hypopnoeas. 291 respiratory events occurred in 24 routine overnight polysomnographic (PSG) studies performed on children (19 male and 5 female, mean age 6.7years). PTT measurements were evaluated against the corresponding PSG results pre-scored by 2 blinded observers. Obstructive events showed a mean change of 5.35% (p<0.05), with ±11.54ms standard deviation (SD) and maximal change of 12.94% (p<0.05) from baseline PTT value during tidal breathing. Central events showed a mean 1.42% (p>0.05) change, with ±3.00ms SD and maximal change of 1.98% (p>0.05). PTT was able to categorise central and obstructive respiratory events accordingly, including hypopnoeas. Hence, PTT shows promises to differentiate respiratory events accordingly in absence of motion artefacts and can be a useful tool in a simplified ambulatory screening system for children for sleep-disordered breathing investigation.

The prevalence of obstructive sleep apnea syndrome (OSAS) can be common for infants. Current gold standard for its diagnosis is nocturnal polysomnography (PSG) but this procedure can be complex to perform. Pulse transit time (PTT) shows potential to indicate abrupt blood pressure (BP) changes during upper airway obstruction. Objective of this study was to assess the capability of PTT to differentiate central from obstructive sleeping respiratory events. This study involved 4 infants with mean age of 7.8 ± 1.9months. 58 valid respiratory events free from motion artefacts were pre-scored by 2 blinded observers. PTT results were then evaluated against the corresponding PSG scorings. Tidal breathing varied with standard deviation (SD) of 5.13ms and maximal decrease of 3.57% from baseline. Obstructive events showed a mean change of 4.95% (p<0.05), with SD of 13.10ms and maximal decrease of 14.92% (p<0.05) from tidal breathing. Central events showed a mean 1.72% (p>0.05) change, with SD of 2.47ms and maximal decrease of 2.90% (p>0.05). PTT is able to categorise central and obstructive respiratory events accordingly. Furthermore, PTT has showed its sensitivity to monitor marginal BP fluctuations during tidal breathing. Hence, preliminary results suggest that PTT can be a valuable OSAS screening tool for infants.

Increased arterial stiffening can be an indication of cardiovascular disease. Pulse wave velocity (PWV) has shown to be a direct measure of this property. However, the assessment of the elastic properties of arteries is hampered by the absence of techniques to estimate arterial pulse pressure non-invasively. Pulse transit time (PTT) is a simple and non-invasive method derived from PWV that has shown potential in cardiovascular and respiratory studies. Limited knowledge on PTT is found in the present literature, especially for children. The aim of this study was to describe prediction equations for healthy children aged 5 to 12 years. 61 children (41 male and 20 female) were studied. Predictive equations for PTT were obtained by multiple regressions with age, vascular path length, blood pressure indexes and heart rate. The derived equations were compared in their PWV equivalent against 2 previously reported equations. Significant agreement was obtained with these 2 equations (p<0.05). The use of PTT measurement in a clinical environment is still to realise its full potential for children. The data and prediction equations here supplement the existing limited data in childhood PTT investigation.

Conventional overnight polysomnography (PSG) used to determine the respiratory behaviour during sleep can be a complex and expensive procedure. Pulse transit time analysis (PTT) has shown potential to detect obstructive apnoeic and hypopnoeic events in adults. This study was undertaken to determine the potential of PTT to differentiate responses to upper airway obstruction. 103 obstructive respiratory events occurred in PSG studies performed on 11 children (10 male and 1 female, mean age 7.5years). PTT measurements were evaluated against the corresponding PSG results pre-scored by 2 blinded observers. Broadly, there were 2 types of responses. They can be either short period of rapid PTT decreases (Type 1) or prolonged but gradual PTT decreases (Type 2). Type 1 obstructive events showed a mean change of 51.77% (p<0.05), with ±8.48ms standard deviation (SD) (p<0.05) and maximal change of 54.80% (p<0.05) from baseline PTT value during tidal breathing. Type 2 events showed a mean 12.01% (p<0.05) change, with ±5.28ms SD (p<0.05) and maximal change of 13.32% (p<0.05). PTT was able to categorise different responses during obstructive respiratory events. The results attained here can suggest that PTT can have greater potentials for use in childhood respiratory sleep studies.

Pulse transit time (PTT) is a non-invasive measure of arterial compliance and can be used for measurement of instantaneous blood pressure (BP) changes during respiratory-related studies. Two common postures adopted in such studies are sitting and supine. However, the relationship between PTT and these postures in children has yet been investigated. The objective of this study was to evaluate the differences in PTT between the recording postures and peripheries in normal children. Retrospective studies were conducted on 24 children mean age of 8.6 years. Sitting posture showed a mean PTT difference of 61.2 ± 8.1ms or 23.9 ± 3.0% (p<0.05) between peripheral sites while supine posture registered 100.4 ± 12.2ms or 43.7 ± 4.4% (p<0.05). The principal contributor to this discrepancy was the lower limb where PTT differed by 42.9 ± 10.3ms or 14.3 ± 3.3% (p<0.05) for sitting and supine posture respectively while, upper limb showed negligible difference of -3.3 ± 3.0ms or -1.4 ± 1.3% (p>0.05). Postural change caused a distinctive PTT differences in children at the lower limbs only due to the higher hydrostatic pressure changes experienced at these peripheries. Hence, PTT measure can be used as a simple and continuous non-invasive BP monitoring in children.