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J K Triedman

Publications and source records attributed to J K Triedman.

46 records · Page 3Linked to original sources
PubMed1994

Comparison of intraarterial with continuous noninvasive blood pressure measurement in postoperative pediatric patients.

OBJECTIVE: The purpose of this study was to estimate the accuracy, bias, and frequency response of continuous blood pressure monitoring using finger photoplethysmography in children. METHODS: To compare arterial blood pressure measured using the Finapres device with simultaneously measured intraarterial blood pressure we studied 27 randomly selected postoperative pediatric patients who were receiving a variety of inotropic and vasoactive agents at a cardiac intensive care unit in university-affiliated pediatric hospital. RESULTS: Sixty-two of 66 attempts (94%) to obtain a noninvasive blood pressure measurement were successful. A total of 37,351 paired blood pressure measurements from 53 records were compared, revealing a measurement bias of -18.6 mm Hg for systolic blood pressure and -13.4 mm Hg for diastolic blood pressure. The measurement bias increased proportionately to blood pressure, with systolic and diastolic gains between the noninvasive and intraarterial techniques of 0.86 and 0.75 mm Hg/mm Hg, respectively. The variation bias during each recording epoch, as measured by standard deviation of bias, was low (mean sigma systolic = 2.9 mm Hg; mean sigma diastolic = 2.0 mm Hg). The frequency response between the intraarterial and noninvasive pressure waveforms was flat to 10 Hz and approximately equal to 1. CONCLUSIONS: Substantial measurement bias exits between this noninvasive blood pressure measurement technique and intraarterial blood pressure. Measurements of the intrapatient variability and frequency response analysis suggest that the noninvasive technique accurately tracks intraarterial blood pressure over the short term. This technique may have useful applications in settings where intraarterial monitoring is undersirable or unobtainable.

Adolescent↗
PubMed1994

Blood pressure modulation by central venous pressure and respiration. Buffering effects of the heart rate reflexes.

BACKGROUND: Despite constant fluctuations in cardiac preload caused by the effects of respiration and changes in posture on venous return to the heart, arterial blood pressure remains remarkably constant. The effects of instantaneous lung volume (ILV) and variations of central venous pressure (CVP) on blood pressure (BP) were studied by use of frequency domain techniques to quantify the contribution of heart rate (HR) reflexes to attenuation of the effects of changes in right ventricular preload on arterial pressure. METHODS AND RESULTS: Random independent variation of ILV, then CVP (obtained using lower-body negative pressure), was performed in eight humans in the supine position. HR, ILV, CVP, and systolic (SBP) and diastolic (DBP) BPs were recorded during control periods and after complete blockade obtained by use of 0.04 mg/kg atropine and 0.2 mg/kg propranolol. A frequency-domain analysis was performed on pairwise relations by the cross-spectral technique. During autonomic blockade, fluctuations in CVP were induced up to 0.14 Hz but caused corresponding changes in arterial pressure only up to 0.08 Hz (P < .02), indicating a mechanical damping effect of the heart and pulmonary vasculature. Fluctuations of BP were also delayed from CVP by 1.55 to 2.10 seconds. At frequencies < 0.1 Hz, relations of CVP to all indices of BP increased with blockade (CVP-SBP, 0.9 +/- 0.5 versus 2.7 +/- 0.8 mm Hg/mm Hg, P < .01; CVP-DBP, 1.3 +/- 0.4 versus 4.3 +/- 1.4 mm Hg/mm Hg, P < .01; CVP-pulse pressure [PP], 1.0 +/- 0.3 versus 1.9 +/- 0.8 mm Hg/mm Hg, P < .05). Higher-frequency fluctuations of arterial BP were a relatively pure manifestation of respiratory activity. At frequencies from 0.15 to 0.35 Hz, the relation of ILV to SBP was unchanged with blockade, whereas relations of ILV to DBP and PP decreased (ILV-DBP, 6.1 +/- 3.5 versus 3.3 +/- 2.2 mm Hg/L, P < .02; ILV-PP, 7.0 +/- 4.3 versus 2.7 +/- 2.2 mm Hg/L, P < .01). An associated change in phase of these relations suggested that neurally mediated changes in HR may offset mechanical effects caused by respiration. CONCLUSIONS: Both slow changes of BP (< 0.08 Hz) induced by variations of CVP and more rapid changes induced by ILV are actively buffered by heart rate reflexes. During blockade, the mechanical properties of interposed cardiopulmonary structures limit CVP-induced fluctuations of BP. These findings have implications for BP regulation in pathological conditions associated with impairment of HR control.

Adult↗
PubMed1993

Prevalence and risk factors for aortopulmonary collateral vessels after Fontan and bidirectional Glenn procedures.

OBJECTIVES: The purpose of this study was to evaluate the prevalence of and risk factors for aortopulmonary collateral vessels in patients who have undergone a bidirectional Glenn or Fontan procedure, or both. BACKGROUND: Aortopulmonary collateral vessels are frequently observed angiographically in patients after a bidirectional Glenn or Fontan procedure. These vessels may provide a source of pulmonary blood flow competitive with anterograde cavopulmonary flow. METHODS: We performed a retrospective study of all patients (n = 196) who underwent catheterization between January 1, 1988 and February 29, 1992 (n = 268) after bidirectional Glenn or Fontan procedures and reviewed clinical, hemodynamic and angiographic phone data. RESULTS: Collateral vessels were diagnosed in 36% of patients. Patients who underwent the bidirectional Glenn procedure were more likely to have collateral vessels than patients who underwent the Fontan procedure (65% vs. 30%, respectively; p < 0.0001). Patients with a history of a Blalock-Taussig shunt were more likely to have collateral vessels than those without (50% vs. 24%, respectively; p = 0.0006). Discretely identifiable collateral vessels were measurable in 54 (20%) of 268 catheterizations. The total estimated cross-sectional area of these vessels averaged 10.7 +/- 7.2 mm2. In patients who underwent the bidirectional Glenn procedure, a step-up in oxygen saturation from the superior vena cava to the distal pulmonary arteries or an upper lobe filling defect, or both, on pulmonary angiogram predicted total estimated cross-sectional area of collateral vessels. Most collateral vessels originated from the internal mammary arteries (34%) and the thyrocervical trunks (22%). Only 9% of collateral vessels arising from the brachiocephalic vessels were visualized by aortogram; the remainder required selective angiography in the subclavian or more distal arteries. CONCLUSIONS: Aortopulmonary collateral vessels are common after bidirectional Glenn and Fontan procedures. Aortograms often fail to diagnose their presence. The left to right shunt carried by these vessels is associated with a step-up in oxygen saturation in the distal pulmonary arteries. The clinical significance and indications for closure of these vessels are not known.

Adolescent↗
PubMed1993

Mild hypovolemic stress alters autonomic modulation of heart rate.

In response to changes in central venous volume, changes in vagal efferent cardiac outflow have been demonstrated in animals but not in humans. In this study, frequency domains analysis was used to quantify modulation of heart rate by respiration and blood pressure in normal human adults undergoing mild central hypovolemic stress induced by blood donation and postural change. In supine subjects, blood donation caused no change in mean heart rate, pulse pressure, or in the variance of heart rate or blood pressure. There were small decreases in mean and systolic blood pressure. A significant decrease in vagal modulation of heart rate was seen in the 0.12-0.5-Hz frequency band, as measured by the change in the relation of lung volume to heart rate in this frequency band (-4.49 beats per minute [pbm] per liter [1], p < 0.001). Comparison of supine and tilt positions revealed marked changes in heart rate and blood pressure means and variances consistent with more pronounced decreases in intracardiac filling pressures and unloading of the arterial baroreceptors. A further progressive decrease in the vagal modulation of heart rate by lung volume was observed in the 0.12-0.5-Hz band, with a near-linear response of magnitude of respiratory sinus arrhythmia over a range of estimated central venous volume. Transfer function analysis can detect changes in autonomic response to mild degrees of central hypovolemia, which are insufficient to cause changes in mean heart rate or heart rate variance. This represents evidence for modulation of heart rate control by cardiopulmonary baroreceptors. A near-linear relation between magnitude of respiratory sinus arrhythmia and central venous volume suggests that this may have clinical relevance in patient monitoring.

Adult↗
PubMed1989

A randomized clinical trial of 10% pentastarch (low molecular weight hydroxyethyl starch) versus 5% albumin for plasma volume expansion after cardiac operations.

Pentastarch is a hydroxyethyl starch similar to hetastarch, but with a lower average molecular weight (264,000 versus 450,000) and fewer hydroxyethyl groups (molar substitution ratio = 0.45 versus 0.70). These characteristics result in enhanced enzymatic hydrolysis, faster renal elimination (initial intravascular half-life = 2.5 versus 25.5 hours), and less effect on coagulation. We report on a randomized clinical trial comparing the clinical efficacy and safety of 10% pentastarch (group P) for plasma volume expansion after cardiac operations with that of 5% serum albumin (group A). During the first 24 hours after arrival of the patient in the intensive care unit, colloid was infused to maintain a cardiac index of 2.0 L/m2 or more and a mean arterial pressure within 10% of the preinduction value. Group P (n = 50) received 1706 +/- 393 ml of colloid (mean +/- standard deviation) during this period, and group A (n = 44), 1794 +/- 341 ml (p = no significant difference). Hemodynamic responses to infusion were similar for both groups, although in group P a greater increase in both cardiac index (0.5 +/- 0.5 versus 0.3 +/- 0.5 L/min/m2 in group A, p less than 0.01) and left ventricular stroke work index (10.8 +/- 8.0 versus 5.8 +/- 6.0 gm-m/m2, p less than 0.01) was observed during infusion of the first 500 ml. There were no significant differences in any of the measured respiratory parameters (alveolar-arterial oxygen gradient, estimated shunt fraction, and effective pulmonary compliance). Hemodilution with colloid significantly reduced serum protein levels in group P by 24 hours postoperatively (4.0 +/- 0.6 versus 5.0 +/- 0.7 gm/dl in group A, p less than 0.05), although mean serum colloid osmotic pressure was similar (15.4 +/- 2.6 [P] versus 15.5 +/- 2.7 mmHg [A], p = no significant difference). There were no significant between-group differences in prothrombin time, activated partial thromboplastin time, platelet count, bleeding time, or coagulation factors (fibrinogen, V, VII, VIII, or IX) on postoperative days 1 and 7. Perioperative fluid balance, weight change, chest tube output, red blood, platelet, or fresh frozen plasma usage, reexploration for bleeding, and clinical outcome were also similar. These findings indicate that pentastarch is as safe and effective s 5% albumin for plasma volume expansion after cardiac operations with no apparent adverse effects on coagulation. If commercially available at a lower cost than albumin, it would appear to be a reasonable first choice for colloid therapy in this setting.

Aged↗