Normal Hemodynamic Parameters Research Articles

Redo in aortic homograft replacement: Transcatheter aortic valve as a valid alternative to surgical replacement

CLINICAL SUMMARY A 48-year-old woman was referred to our hospital with symptoms of ingravescent severe dyspnea. Fifteen years earlier, she had undergone placement of a 21-mm aortic valve Bravo 400 stentless xenograft (Cryolife International, Atlanta, Ga). Four years later, she underwent a valve replacement with a 21-mm mechanical prosthesis (Carbomedics, Austin, Tex) for valve degeneration, and subsequently, she received a homograft for aortic valve endocarditis. The echocardiographic control, performed during the last 15 years, showed progressive calcific valve degeneration with a peak transvascular pressure gradient of 41 mm Hg and aortic valve area of 0.5 cm. Preoperative computed tomographic angiographic analysis showed diffuse aortic root

Acute neurotoxicity after yohimbine ingestion by a body builder

Yohimbine is an alkaloid obtained from the Corynanthe yohimbe tree and other biological sources. Yohimbine is currently approved in the United States for erectile dysfunction and has undergone resurgence in street use as an aphrodisiac and mild hallucinogen. In recent years yohimbine use has become common in body-building communities for its presumed lipolytic and sympathomimetic effects. We describe a 37-year-old bodybuilder in which severe acute neurotoxic effects occurred in 2 h after yohimbine ingestion. The patient presented with malaise, vomiting, loss of consciousness, and repeated seizures after ingestion of 5 g of yohimbine during a body-building competition in a gymnasium. His Glasgow Coma Score was 3, requiring orotracheal intubation. Two hours after admission, vital signs were blood pressure 259/107 mmHg and heart rate 140 beats/min. Treatment with furosemide, labetalol, clonidine, and urapidil and gastrointestinal decontamination were performed. Twelve hours later the patient was extubated with normal hemodynamic parameters and neurological examination. The yohimbine blood levels at 3, 6, 14, and 22 h after ingestion were 5,240; 2,250; 1,530; and 865 ng/mL, respectively, with a mean half-life of 2 h. Few data are available about yohimbine toxicity and the related blood levels. This is a case of a large ingestion of yohimbine in which severe hemodynamic and neurological manifestations occurred and elevated blood levels of yohimbine were detected.

Exercise tests during cardiac catheterisation in patients with mitral regurgitation (author's transl)

Left-heart catheterisation with angiocardiography and right-heart catheterisation during exercise were performed in ten patients with pure chronic mitral regurgitation. Those patients who at rest had large normal haemodynamic parameters had a rise in pulmonary wedge pressure on exercise from 13.1 +/- 4.8 to 26.0 +/- 9.1 mm Hg (P less than 0.001), as well as subsequently an exercise-induced pulmonary hypertension with a rise in pulmonary arterial mean pressure from 20.9 +/- 8.9 to 36.5 +/- 10.3 mm Hg (P less than 0.001). In addition, there occurred abnormalities of right ventricular function in four patients during exercise, with a rise in right atrial mean pressure above 10 mm Hg. On the other hand, in 12 patients with pure mitral stenosis and higher pressures in the pulmonary artery on exercise (43.9 +/- 10.2 mm Hg) (P less than 0.1), there was no abnormal rise in right atrial pressure. In patients with mitral regurgitation associated with abnormal right ventricular function during exercise, left ventricular function at rest was impaired (ejection fraction under 51%). There was a reciprocal correlation (r = -0.86) between the left ventricular ejection fraction at rest and the level of pulmonary artery pressure on exercise. Exercise-induced pulmonary hypertension in chronic mitral regurgitation with largely normal pressure values at rest is thus less the result of volume overload of the pulmonary circulation than an expression of impaired left ventricular pumping action. Abnormal right ventricular function which occurs on exercise is not a secondary consequence of pulmonary hypertension but goes parallel with abnormal function of the left ventricle.

N-Terminal Pro-B-Type Natriuretic Peptide as an Indicator of Disease Severity in a Heterogeneous Group of Patients With Chronic Precapillary Pulmonary Hypertension

N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) is well established as a predictor of prognosis in patients with left ventricular dysfunction. Although a similar prognostic significance has been suggested in 1 study of right ventricular failure and idiopathic pulmonary arterial hypertension, NT-pro-BNP has not been assessed as a marker of disease severity in a more heterogenous group of patients with chronic precapillary pulmonary hypertension (PH). Hence, this study assessed plasma NT-pro-BNP and other clinical variables in 61 consecutively recruited patients with various forms of chronic precapillary PH. Right-sided cardiac catheterization and cardiopulmonary exercise testing were performed at baseline, and the prognostic significance of NT-pro-BNP was investigated with a mean follow-up of 25 months. Compared with age-matched controls (n = 10), plasma NT-pro-BNP was significantly greater in those with idiopathic pulmonary arterial hypertension (n = 16), chronic precapillary PH associated with other diseases (n = 26), and chronic thromboembolic disease (n = 19) and was correlated with hemodynamic variables and functional capacity. In 17 medically treated patients, the significant decrease in NT-pro-BNP levels correlated with improved hemodynamics. During follow-up, 15 patients died from cardiopulmonary causes. Baseline NT-pro-BNP was an independent predictor of mortality. Kaplan-Meier survival analysis according to the median value of NT-pro-BNP (168 pmol/L) demonstrated a significantly higher mortality rate in those with supramedian values than in those with low plasma levels (p = 0.010). In conclusion, these findings suggest that in a heterogenous group of patients with chronic precapillary PH, plasma NT-pro-BNP can be used to determine the clinical severity of disease and is independently associated with long-term mortality.

Initial resuscitation of hemorrhagic shock

The primary treatment of hemorrhagic shock is control of the source of bleeding as soon as possible and fluid replacement. In controlled hemorrhagic shock (CHS) where the source of bleeding has been occluded fluid replacement is aimed toward normalization of hemodynamic parameters. In uncontrolled hemorrhagic shock (UCHS) in which bleeding has temporarily stopped because of hypotension, vasoconstriction, and clot formation, fluid treatment is aimed at restoration of radial pulse, or restoration of sensorium or obtaining a blood pressure of 80 mmHg by aliquots of 250 ml of lactated Ringer's solution (hypotensive resuscitation). When evacuation time is shorter than one hour (usually urban trauma) immediate evacuation to a surgical facility is indicated after airway and breathing (A, B) have been secured ("scoop and run"). Precious time is not wasted by introducing an intravenous line. When expected evacuation time exceeds one hour an intravenous line is introduced and fluid treatment started before evacuation.Crystalloid solutions and blood transfusion are the mainstays of pre-hospital and in-hospital treatment of hemorrhagic shock. In the pre-hospital setting four types of fluid are presently recommended: crystalloid solutions, colloid solutions, hypertonic saline and oxygen-carrying blood substitutes. In unstable or unresponsive hemorrhagic shock surgical treatment is mandatory as soon as possible to control the source of bleeding.

Intra-operative Doppler Flow Measurement do not Predict ‘At-risk’ Status of Infrainguinal Bypass Grafts

AimsPatients undergoing infrainguinal arterial reconstruction using vein conduits, frequently undergo intra-operative Doppler flow measurements to determine technical adequacy. The aim of this study was to determine the proportion of vein grafts with normal intra-operative haemodynamic parameters that were subsequently discovered to be ‘at risk’ on post-operative duplex surveillance scanning. MethodsWe prospectively collected data on 82, primary infrainguinal vein bypass grafts. Post papaverine graft flow and peripheral resistance were measured using the Scimed Opdop® intra-operative Doppler machine. All grafts were determined to be technically adequate on the basis of measured peripheral resistance units (mPRU) being ≤1. At 1 week, a post-operative duplex surveillance scan was performed. At risk status was determined and compared to the intra-operative Doppler flow measurement. Statistical analysis was performed using the Mann–Whitney U-test. ResultsThe post-operative duplex scan demonstrated that 53 (65%) of the 82 vein bypass grafts were diagnosed as being ‘not at risk’; and 29 (35%) were regarded as at risk. When the groups were compared, there was no significant difference in intra-operative haemodynamic parameters between those not at risk and those at risk (P=0.19, Mann–Whitney U-test). The 1 month primary patency rate was 79% with a secondary patency rate of 100%. ConclusionDespite normal intra-operative Doppler flow measurements, 35% of vein grafts were regarded as being at risk at the 1 week post-operative duplex surveillance scan. No single value may be universally applicable for identifying at risk grafts intraoperatively. Indeed, graft failure appears to be a multifactorial process.

Targeted resuscitation strategies after injury

The management of the traumatically injured patient has evolved during the past half century despite continually high morbidity and mortality rates. The management of the trauma victim requires timely intervention and damage control in an attempt to maintain normal hemodynamic parameters and adequate systemic perfusion. There is a fine balance between oxygen delivery and consumption, and when this is perturbed, oxygen debt may ensue. The presence of ongoing oxygen debt is rather deleterious, resulting in an inflammatory cascade that can lead to multisystem organ dysfunction. The rapid identification and restoration of oxygen debt are central to the resuscitation of the critically ill patient, be it the result of sepsis or trauma. Resuscitation end points have evolved that allow the physician to more rapidly identify a perturbation between oxygen delivery and consumption. Moreover, end points allow uniformity in gauging the adequacy of resuscitation: preventing under- and overresuscitation and serving as a basis to compare outcome measures in resuscitation trials. Recent technologic advances have allowed a greater wealth of clinical data that can be obtained via less invasive means. Examples of this include esophageal Doppler monitoring, sublingual capnography, orthogonal polarization spectral imaging, and lithium dilution cardiac output determinations. These devices can be used in concert with more traditional resuscitation end points (ie, lactate and base deficit) to maximize oxygen delivery and correct tissue dysoxia. In addition, the management of hemorrhagic shock is continuing to evolve and challenge the dogmatic practices of normotensive resuscitation. This review addresses (1) resuscitation end points to optimize cardiac function, (2) resuscitation end points to assess the microcirculation, (3) recent developments in the management of hypotensive hemorrhagic shock, and (4) the translation of early goal-directed therapy from septic shock to use in trauma. Past findings are reflected on and direction for future investigation and clinical practice based on recent clinical advances is provided.

Hemodynamic Effects of Arteriovenous Fistula in End‐Stage Renal Failure

Hemodynamic parameters using Swan Ganz catheter were studied in 17 patients with end stage renal disease. The acute effects of radiocephalic AV fistula on the hemodynamic parameters were studied at 24 hours of surgery. The chronic effects were studied in 8 of these patients at 6 weeks of arteriovenous (AV) fistula. The AV fistula matured in 3 to 4 weeks time and blood flow was sufficient for hemodialysis (400 mL/min). Patients with chronic renal failure had normal or high normal hemodynamic parameters. Six weeks after the AV fistula, the cardiac index and the stroke volume index slightly increased along with a significant increase in systolic and mean systemic arterial pressure. None of the patients had significant increase in cardiac filling pressures. Although there was some fall in systemic vascular resistance index and rise in cardiac index and stroke volume index, these changes were physically small and unlikely to put any extra hemodynamic load. Thus, AV fistula in dialysis patients is not an appreciable cause of circulatory or pulmonary congestion.

Fluid resuscitation strategies in the Israeli army.

Medical training in the Israel Defense Forces (IDF) is currently based on the principles of the Advanced Trauma Life Support course of the American College of Surgeons termed Military Trauma Life Support. The Advanced Trauma Life Support guidelines provide a systematic standardized approach to the treatment of trauma casualties that has been very successful in civilian trauma. On the battlefield, however, these guidelines have been modified according to the combat environment. The factors that influence these changes are tactical considerations, availability and level of training of medical personal, direct enemy fire, medical equipment limitations, means of transportation of casualties, and the variable transportation time from the front line to the first medical echelon. The basic strategy of the IDF is to bring the military physician or paramedic and airlifted surgical units as close as possible to the front line, to minimize evacuation time. Also, evacuation helicopters that land in the combat zone close to the front line, sometimes under direct fire, usually have a military physician on board. The dilemma of "scoop and run" or "stay and stabilize" in hemorrhagic shock has been solved in the IDF toward early rapid evacuation of casualties to a surgical unit. Immediately after airway and breathing have been secured, if evacuation time is less than 1 hour, the intravenous line and fluid resuscitation is started en route to the medical facility. When evacuation time is longer than 1 hour, an intravenous line is always started before evacuation. In controlled hemorrhagic shock, where the source of bleeding has been controlled and evacuation time is less than 1 hour, fluid resuscitation with lactated Ringer's solution or normal saline is started, to achieve normalization of hemodynamic parameters. When evacuation time exceeds 60 minutes, colloids such as Hemaccel or hydroxyethyl starch are added. In uncontrolled hemorrhagic shock, where internal bleeding has temporarily stopped because of hypotension, vasoconstriction, and thrombus formation, aggressive fluid resuscitation with lactated Ringer's solution to achieve normal hemodynamic parameters is prohibited, because it may induce internal rebleeding and hemodynamic decompensation. When evacuation time exceeds 60 minutes, the use of crystalloids and colloids is indicated. If brain injury is suspected, fluid resuscitation should be aimed toward normalization of hemodynamic parameters.

The value of natriuretic peptides NT-pro-BNP and BNP for the assessment of left-ventricular volume and function. A prospective study of 150 patients

An early detection of patients with left-ventricular (LV) dysfunction is essential for effective treatment of congestive heart failure. The B-type natriuretic peptide (BNP) was described as a strong diagnostic parameter of LV-dysfunction. Aim of this study was to compare the diagnostic value of BNP and the aminoterminal part of pro-BNP (NT-pro-BNP) within an heterogenous patient population. NT-pro-BNP and BNP were measured in 150 hospitalized cardiologic patients (age-median 64 years, 109 male versus 41 female). The values were correlated with clinical and haemodynamic parameters of the invasively determined LV-function. Patients with pathologic haemodynamic values of the LV-function had significantly higher NT-pro-BNP and BNP levels than patients with normal haemodynamic parameters. In our study population a severe systolic LV-dysfunction (ejectionfraction EF<40 %) could be detected with a sensitivity and specifity of 100 % and 64 % by NT-pro-BNP and 100 % and 45 % by BNP. Sensitivity and specifity for the detection of any systolic dysfunction (EF<60 %) and of a systolic or diastolic dysfunction, respectively, were 94 %, 37 % and 88 %, 41 % for NT-pro-BNP (94 %, 40 % and 84 %, 44 % for BNP). The corresponding negative predictive values were 100 %, 96 % and 71 % for NT-pro-BNP and 100 %, 96 % and 68 % for BNP. NT-pro-BNP and BNP were highly sensitive diagnostic parameters with a very good negative predictive value for LV-dysfunction. Because of the uncomplicated measurement, they could be used effectively to rule out LV-dysfunction in cardiovascular high risk patients by general practitioners.

Cardiovascular phenotypes of kinin B2 receptor- and tissue kallikrein-deficient mice.

To clarify the role of the kallikrein-kinin system in cardiovascular homeostasis, the systemic and regional hemodynamics of kinin B2 receptor-deficient (B2-/-) and tissue kallikrein-deficient (TK-/-) mice were compared with their wild-type (WT) littermates on a pure C57BL/6 genetic background. B2-/-, TK-/-, and WT adult mice were normotensive and displayed normal hemodynamic (left ventricular [LV] pressure, cardiac output, total peripheral resistance, dP/dt(max)) and echocardiographic (septum and LV posterior wall thickness, LV diameter, LV mass, and LV fractional shortening) parameters. However, heart rate was lower in B2-/- mice compared with TK-/- and WT mice. In addition, B2-/- mice, but not TK-/- mice, exhibited lower coronary and renal blood flows and greater corresponding vascular resistances than did WT mice, indicating a tonic physiological vasodilating effect of bradykinin in these vascular beds. However, maximal coronary vasodilatation capacity, estimated after dipyridamole infusion, was similar in the 3 groups of mice. B2-/- mice were significantly more sensitive than were TK-/- mice to the vasoconstrictor effects of angiotensin II and norepinephrine. Finally, renin mRNA levels were significantly greater in B2-/- mice and smaller in TK-/- mice compared with WT mice. Taken together, these results indicate that under basal conditions, the kinin B2 receptor is not an important determinant of blood pressure in mice but is involved in the control of regional vascular tone in the coronaries and the kidneys. The phenotypic differences observed between TK-/- and B2-/- mice could be underlain by tissue kallikrein kinin-independent effect and/or kinin B1 receptor activation.

Um circuito simples com bomba única para circulação extracorpórea com oxigenação autógena

It was tested in 30 dogs a circuit capable to allow extracorporeal circulation (ECC) with autogenous oxygenation (AO) of the blood employing an only centrifugal pump. With this assembly is unnecessary a pump to the right side: the gradient of transpulmonary pressure was obtained by increasing the pulmonary artery pressure by volemic expansion and decreasing the left atrial pressure by draining this camera by means of a siphon. The heart was electrically fibrillated in the beginning of the bypass and defibrillated in the end. This circuit allowed the maintenance of normal hemodynamic parameters and normal blood gases level during ECC. The operative field and the mobility of the heart were similar to those provided by conventional CEC. We concluded that the use of an only centrifugal pump simplifies ECC with AO, turning it a practical choice for the procedures of myocardial revascularization.

Right ventricular ejection function assessed by cineangiography--Importance of bellows action.

The right ventricular ejection fraction (RVEF) can be shown theoretically as a mathematical function of the percent shortening in the 3 axial dimensions of the right ventricular cavity (the septum-free wall dimension (SF), the anterior-posterior dimension (AP), and the tricuspid valve-apex dimension (TA) or the long axis dimension (LA)). There is a need to decide which mechanism is the most important for the RVEF in cases with neither obvious regional wall motion abnormalities of the left ventricle nor right ventricular overload. Forty-four consecutive subjects (34 males/10 females) were enrolled: 16 had normal hemodynamic parameters without significant coronary artery stenosis, 15 had hypertrophic cardiomyopathy and 13 had dilated cardiomyopathy. Biplane right ventricular cineangiography was performed and the percent shortening of the SF, AP, and TA or LA were measured. The percent shortening in the SF (34.8+/-14.7%) was larger than that of the AP, TA, and LA (23.2+/-8.5, 21.0+/-8.3 and 18.3+/-7.0, respectively; all p<0.001). There was a linear correlation between the percent shortening of each dimension and the RVEF. The 95% confidence interval of the regression equation from the percent shortening of the SF and RVEF was located above those from the other percent shortenings, except for a lower RVEF. These results indicate that systolic shortening of the SF (ie, bellows action) plays an important role in the RVEF except for a lower ejection fraction.

Chapter Nine: Medical Management of the Shaken Infant

Summary The medical management of the Shaken Infant is challenging and frustrating. Severe traumatic and hypoxic-ischemic injuries commonly occur in these patients, resulting in significant central nervous system injury. The medical management of these children depends mostly on the severity of central nervous system injury. The infant with isolated traumatic brain injury may benefit from aggressive management of increased intracranial pressure. Otherwise, the major thrust of care for these infants is supportive in nature, maintenance of normal hemodynamic and respiratory parameters, and treatment of seizures. Recognition of SBS is important so that appropriate diagnostic tests can be done and therapies initiated. Because of the devastating nature of these injuries, numerous resources are required to care for survivors. The outcome of infants with severe brain injury is dismal; therefore, prevention is required.

Fetal Death after Trauma in Pregnancy

Trauma in pregnancy places the mother and fetus at risk. The objective of this study is to identify risk factors independently associated with acute termination of pregnancy and/or fetal mortality after trauma. The medical and trauma registry records of 80 injured pregnant patients were reviewed. Data were collected and then analyzed by univariate and multivariate analysis. Three patients died (3.7%), 23 had the pregnancy acutely terminated (30%), and 14 suffered fetal death (17.5%). The only independent risk factors for fetal mortality were an Injury Severity Score (ISS) > or =9 and a nonviable pregnancy (<23 weeks). The combination of both risk factors increased the likelihood of fetal mortality by fivefold over that of patients without either risk factor. Maternal hemodynamic parameters did not predict fetal loss. Two patients lost their fetuses despite insignificant trauma (ISS = 1) and normal hemodynamic parameters, whereas eight delivered normal babies despite major trauma (ISS > or = 16). Hemodynamic stability on admission does not predict fetal mortality. Although the presence of moderate to severe injuries (ISS > or = 9) increases the likelihood of fetal mortality, this complication may occur even with insignificant trauma. Close maternal and fetal monitoring is justified, regardless of maternal hemodynamic presentation or severity of injury.

Attenuated hypoxic pulmonary hypertension in mice lacking the 5-hydroxytryptamine transporter gene.

Hypoxia is a well-recognized stimulus for pulmonary blood vessel remodeling and pulmonary hypertension development. One mechanism that may account for these effects is the direct action of hypoxia on the expression of specific genes involved in vascular smooth muscle cell (SMC) proliferation. Previous studies demonstrated that the serotonin (5-hydroxytryptamine; 5-HT) transporter (5-HTT) mediates the mitogenic activity of 5-HT in pulmonary vascular SMCs and is overexpressed during hypoxia. Thus, 5-HT-related mitogenic activity is increased during hypoxia. Here, we report that mice deficient for 5-HTT (5-HTT(-/-)) developed less hypoxic pulmonary hypertension and vascular remodeling than paired 5-HTT(+/+) controls. When maintained under normoxia, 5-HTT(-/-)-mutant mice had normal hemodynamic parameters, low blood 5-HT levels, deficient platelet 5-HT uptake, and unchanged blood levels of 5-hydroxyindoleacetic acid, a metabolite of 5-HT. After exposure to 10% O(2) for 2 or 5 weeks, the number and medial wall thickness of muscular pulmonary vessels were reduced in hypoxic 5-HTT(-/-) mice as compared with wild-type paired controls. Concomitantly, right ventricular systolic pressure was lower and right ventricle hypertrophy less marked in the mutant mice. This occurred despite potentiation of acute hypoxic pulmonary vasoconstriction in the 5-HTT(-/-) mice. These data further support a key role of 5-HTT in hypoxia-induced pulmonary vascular SMC proliferation and pulmonary hypertension.

Load dependent diastolic dysfunction in heart failure.

Congestive heart failure may result from cardiovascular overload, from systolic or from diastolic dysfunction. Diastolic left ventricular dysfunction may result from structural resistance to filling such as induced by pericardial constraint, right ventricular compression, increased chamber stiffness (hypertrophy) and increased myocardial stiffness (fibrosis). A distinct and functional etiology of diastolic dysfunction is slow and incomplete myocardial relaxation. Relaxation may be slowed by pathological processes such as hypertrophy, ischemia and by asynchronous left ventricular function. The present contribution analyses the occurrence of slow and incomplete myocardial relaxation in response to changes in systolic pressure and in response to changes in venous return. The regulation of myocardial relaxation by load is critically dependent on the transition from myocardial contraction to relaxation, which occurs in dogs when 82% of peak isovolumetric pressure has developed or at a relative load of 0.82. This corresponds to early ejection in normal hearts, but is situated even before aortic valve opening in severely diseased hearts. When load is developed beyond this transition, relaxation becomes slow and even incomplete. This is load dependent diastolic dysfunction. Load dependent diastolic dysfunction occurs in normal hearts facing heavy afterload and in severely diseased hearts even with normal hemodynamic parameters. This dysfunction should contribute to elevating filling pressures in most patients with severe congestive heart failure. This dysfunction can be reverted by decreasing systolic pressures or by decreasing venous return. Load dependent diastolic dysfunction gives us an additional reason to aggressively treat CHF patients with diuretics and vasodilators.

Thrombosis of Angiographic Catheters in Humans: Experimental Study

One of the major problems in the use of catheters is their thrombogenicity since the embolization of clots near the central nervous system or the coronary arteries can cause permanent damage. Catheter thrombogenicity was evaluated in humans during angiographic procedures by their tendency to become occluded. Characterization of catheters was achieved using roughness measurements, FTIR with ATR, DSC and ESCA. The catheters were 5 commercially available catheters, made mainly of polyethylene, Pebax or polyamide sterilized and ready for clinical use. Thirty-one patients due to have an angiographic procedure and with normal blood and hemodynamic parameters were included in the study. The 50 cm catheter test sample was inserted through an introducer into the femoral artery at the beginning of an angiographic procedure. The outcoming blood flow rate (BFR) was continuously monitored by a special computerized device for 15 min or until the total amount of blood reached 30 ml. The angiographic procedure was then normally resumed. DSC and FTIR showed results consistent with the expected composition of catheters. ESCA results showed very high Si/C ratios and could not be explained in all instances. Occlusion of the catheters occurred in 44% of the cases and the average time to obtain occlusion was 8.5 min (3-15 min). Values of the decrease rate of BFR in ml/min2 allowed separation of the catheters into 3 groups of low, medium and high thrombogenicity. However, occlusion occurred at least one time for each type of catheter. Blood volume and BFR curves vs. time allowed the determination of 3 main types of thrombotic behavior: type I shows no significant reduction of BFR; type II shows a progressive decrease in flow rate; type III is much less frequent and shows an abrupt decrease of BFR either quickly followed by a compensatory increase and resuming of a steady flow or by abrupt occlusion. In type II curves the pattern of occlusion follows a classical diffusion model because the Peclet number is greater than 1 and then the classical Higbie solution for diffusion could be used. The most thrombogenic material was the smoothest. There was no correlation between surface chemical composition and thrombogenicity. However, catheters that were based on PE appeared less thrombogenic than PA catheters in this study.

Utilisation de cathéters veineux ombilicaux double voie en unité de soins intensifs néonatals

The aim of the study was to compare the success/failure rate and complications of insertion into the umbilical vein, of either double-lumen catheters (Charrière diameter 04, length 13 and 30 cm) or single-lumen catheters (Charrière diameter 05, length 40 cm) in a population of neonates admitted to a neonatal intensive care unit. The numbers of insertions of additional peripheral venous catheters were also compared. The population was divided into two groups according to the severity of the respiratory failure. Group 1 (n = 52): normal hemodynamic parameters and moderate respiratory failure (FiO2 < 0.6): only single-lumen catheters were used. Group 2 (n = 56): low systemic pressure requiring vascular filling and/or inotropic drugs infusion and/or severe respiratory failure (FiO2 > 0.6): in this group, either single-lumen catheters or double-lumen catheters were inserted. The success rate of insertion of double-lumen catheters and of single-lumen catheters were similar (61% vs 71%: P = 0.7). Nineteen double-lumen catheters were inserted in the group 2. The average duration of double-lumen umbilical catheterization was not significantly different from simple-lumen catheterization (4.9 +/- 2.2 vs 4.6 +/- 2.2 days). Complications relating to the umbilical venous catheterization were uncommon: three catheter obstructions (two with single-lumen catheter, one with double-lumen catheters), two nosocomial infections (both with single-lumen catheter), one hydropericardium (with single-lumen catheter). In group 2, more peripheral venous catheters were required during the first 72 hours of life after insertion of single-lumen catheter than after insertion of double-lumen catheters (average number of peripheral venous catheters per infant: 1.6 +/- 0.83 vs 1 +/- 0.35 respectively; P < 0.01). Feasibility and complication rate of umbilical double-lumen catheters were similar to those of single-lumen catheters. The use of umbilical double-lumen catheters reduces the need of peripheral venous catheters.

Upper Extremity Veno-arterial Shunting during Pediatric Orthotopic Liver Transplantation

Upper Extremity Veno-arterial Shunting during Pediatric Orthotopic Liver Transplantation