Normal Systemic Vascular Resistance Research Articles

Prognostic Value of Maternal Cardiovascular Hemodynamics in Women With Gestational Hypertension and Chronic Hypertension in Pregnancy

This study aimed to assess the prognostic value of cardiovascular assessment in women with gestational hypertension or chronic hypertension for the risk of preeclampsia and need for closer antenatal surveillance. This was a prospective study of pregnancies complicated by gestational hypertension or chronic hypertension presenting to St George's Hospital, between January 2015 and May 2018. A noninvasive ultrasonic cardiac output monitor was used to obtain cardiovascular variables of cardiac output (CO) and systemic vascular resistance (SVR) and weight-adjusted indices. The primary outcome was the time to development of preeclampsia in women with gestational hypertension or chronic hypertension. In women with gestational hypertension or chronic hypertension (n=149), cox-proportional hazards analysis showed that mean arterial pressure (P=0.006), Afro-Caribbean ethnicity (P=0.045), and gestational age at the time of diagnosis above 34 weeks (P<0.001) were significantly associated with increased risk of earlier preeclampsia. Women with high SVR and normal CO (adjusted hazard ratio, 2.32 [95% CI, 1.06-5.08]; P=0.035) and high SVR and low CO (adjusted hazard ratio, 7.79 [95% CI, 1.94-31.24]; P=0.003) cardiovascular profiles had significantly higher risk of earlier preeclampsia compared with women with normal SVR and normal CO. The findings of this study demonstrate that hypertensive women with increased SVR and low CO had a higher risk of developing preeclampsia sooner.

Non-invasive characterization of hemodynamics in adult out-of-hospital cardiac arrest patients soon after return of spontaneous circulation

BackgroundLittle is known about hemodynamics in adult, out-of-hospital (OHCA) patients following return of spontaneous circulation (ROSC). A 1994 study when “high-dose epinephrine” use was common showed consistently elevated systemic vascular resistance (SVR) lasting ≥6 h in 49 adult patients after return of spontaneous circulation (ROSC). Study aimTo characterize hemodynamic abnormalities in adult OHCA patients soon after ROSC. Our hypothesis was that, unlike the consistently high SVR values reported when “high-dose” epinephrine was in common use, there would be a more heterogenous distribution of SVR values using current adrenergic therapy. MethodsWe included adult, OHCA patients transported by paramedics to the Emergency Department (ED) post-ROSC. Children, prisoners, pregnant women, and those with ongoing CPR or arrest due to traumatic injury were excluded. Hemodynamics were recorded non-invasively as soon as feasible after ED arrival but were not used to influence therapy, which was guided by clinical judgment of treating ED physicians. ResultsHemodynamics were recorded on 30 patients 20 [16,25] minutes after ED arrival: 50% had a normal SVR, 30% had a high SVR, and 20% had a low SVR. There was no difference in survival to admission among groups, although there was a difference among groups in survival to discharge. Comparing the low SVR group vs the combined normal and high group revealed a trend for fewer 0/6 (0%) low vs. 10/24 (42%) normal or high SVR patients surviving to hospital discharge (p = .053). ConclusionA heterogeneous range of hemodynamic states exist post-ROSC rather than consistent vasoconstriction. Adequately powered, randomized clinical trials will be needed to determine whether noninvasively-derived, hemodynamic-directed therapy can play a role in improving neurologically-intact survival following OHCA in adults.

Scorpion bite, a sting to the heart!

Sir, We read the article “Scorpion bite, a sting to heart” by Agrawal et al.[1] with great interest. The author reported a case of 14-year-old male patient with scorpion bite on the right toe. We want to highlight certain issues regarding diagnosis and management of this patient. Cardiotoxic effects due to scorpion bite are not rare complications as demonstrated by Kumar et al. that almost more than one-third of these patients have one or more cardiovascular effects.[2] Prazosin and anti-scorpion venom (SAV) should be the primary line of treatment, as alpha receptors stimulation by the toxin results in hypertension, tachycardia, myocardial dysfunction, pulmonary edema, and cool extremities.[3] However, it has been seen that the late administration of SAV may be effective as the antivenom creates a concentration gradient between plasma and target tissue. The venom bound to antivenom gets excreted, and the toxin in the tissues moves down the concentration gradient into the blood and gets bound by the antivenom. Therefore, even if the venom is not immediately neutralized by antibodies, its removal from the tissue may cause relief in symptoms.[3] Electrocardiography (ECG) is the most important and easily available tool. No victim with systemic involvement shows normal ECG. RST segment and T waves are most frequently affected. Early myocardial infarction-like pattern, atrial arrhythmias, nonsustained ventricular tachycardia and varied conduction defect due to injury to the conducting system are seen. Conduction defect restore to normal within 1 week, T wave inversion persist for a few weeks. At times, despite good clinical status of the victim, ECG showed mark abnormalities.[4] Echocardiography is a useful tool for evaluating the various parameters of cardiac function. Echo shows poor global myocardial contractility within 12–15 h of sting, with low ejection fraction, decreased left ventricular performance, and abnormal diastolic filling for 5 days to 4 weeks. Diminished or hypokinetic left ventricular global movement with decrease systolic function was seen in the scintigraphic study. There is a good correlation between clinical improvement and return to normal left ventricular function.[5] Karnad from India studied haemodynamic pattern in eight scorpion sting cases of Mesobuthus tamulus sting. He recorded severe vasoconstriction and hypertension in mild envenoming while predominant left ventricular dysfunction with normal systemic vascular resistance causing pulmonary edema or severe hypotension in severe envenomation.[6] These patients are benefitted by the early use of inotropes and vasodilators, which reduce the afterload on the heart. These physiologic principles make dobutamine and milrinone as vasoactive drugs of choice instead of Noradrenaline as used by authors in the index case. Amiodarone a neuromodulator improves the survival by reduction of serum nor-epinephrine level in four children with scorpion sting who had severe left ventricular dysfunction with raised troponin and serum norepinephrine.[7] Early hospitalization after sting, and administration of SAV are the key factors in reducing the myocardial dysfunction, and hence related morbidity and mortality. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Anaesthesia for repair of anomalous origin of left coronary artery from pulmonary artery.

Sir, Anomalous origin of left coronary artery from pulmonary artery (ALCAPA) is a rare congenital heart defect (1 in 3,00,000 live births), in which left coronary artery arises from pulmonary artery, instead of branching from the aorta.[1,2,3] A 35-year-old, 47 kg female was scheduled for corrective surgical repair of ALCAPA. For the previous 2 years, she had progressively increasing breathlessness and anginal attacks on exertion. The 12 lead electrocardiograms (ECG) revealed sinus rhythm, without any ST or T wave changes. Transthoracic echocardiography revealed mild left ventricular enlargement and normal ejection fraction of 55%, without any regional wall motion abnormalities. The coronary angiography revealed ALCAPA. Her medications included enalapril, digoxin and furosemide. In the operation theatre, after securing a 16 gauge intravenous (IV) cannula, monitoring with ECG, non-invasive blood pressure (BP), cardiac output (CO) and oxygen saturation (SpO2) was started. The left femoral artery and left radial artery were cannulated for invasive BP monitoring. General anaesthesia was induced and trachea intubated using fentanyl 100 μg, morphine 6 mg, midazolam 2 mg, etomidate 6 mg and vecuronium 8 mg (all administered IV). Right internal jugular vein was cannulated, and anaesthesia was maintained using oxygen/air/isoflurane, with infusions of rocuronium and fentanyl. The ventilatory settings were aimed to prevent hypocarbia, hyperoxia and alkalosis. A low FiO2 of 0.4 was used to maintain a high pulmonary vascular resistance (PVR). The end-tidal CO2 was maintained between 40 and 42 mmHg, and partial pressure of oxygen was monitored. The surgery was performed under cardiopulmonary bypass (CPB). Dopamine (5 μg/kg/min) was used during weaning of the patient from CPB. Intra-operatively and post-operatively, patient remained haemodynamically stable. The survival of neonates with ALCAPA varies with the adequacy of left ventricular perfusion. This depends on the inflow of blood to left coronary artery via collaterals from right coronary artery (RCA) and the proportion of coronary steal from left coronary artery to the pulmonary artery. Only 10-20% of these neonates survive till adulthood.[4] In the post-natal period, there is a decrease in pulmonary vascular resistance (PVR) and oxygen content of the pulmonary blood. This can reverse the direction of blood flow from left coronary artery to the pulmonary artery (coronary steal phenomenon). This causes hypo-perfusion of the left ventricular myocardium by relatively de-saturated blood, leading to myocardial ischaemia. This can lead to mitral valve insufficiency.[5,6] Patients might have accompanying atrial septal defect, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot or coarctation of the aorta. All these factors precipitate congestive heart failure in 80–90% of these infants. These neonates present with tachypnoea, tachycardia, poor feeding, irritability and diaphoresis. They can survive till adulthood, due to well-developed collaterals from RCA, which provides adequate perfusion to the left ventricle. The RCA was dilated and tortuous in this patient [Figure 1]. The coronary angiogram is the gold standard investigation for diagnosis of ALCAPA. The adults present with exertional dyspnoea, angina and cardiac arrhythmias.[2] Diuretics and inotropes are used for the management of congestive heart failure. Figure 1 Dilated and tortuous right coronary artery The anaesthetic goals are to (1) maintain optimum preload, (2) prevent a decrease in PVR, (3) maintain myocardial contractility, (4) maintain low or normal systemic vascular resistance (SVR) and (5) prevent tachycardia. The preload is optimized to ensure an adequate CO. In these patients, the stroke volume is monitored instead of CO, because CO varies with heart rate. The laryngoscopy/intubation should be smooth and rapid. Swings in heart rate and BP are avoided. Tachycardia is detrimental, as it can alter the myocardial oxygen supply/demand ratio and predispose to myocardial ischaemia. Etomidate being haemodynamically stable is preferred for induction of anaesthesia. Isoflurane is the inhalational agent of choice, as it causes less myocardial depression, compared with halothane or sevoflurane and is a better myocardial protective agent. Low PVR will accentuate the coronary steal phenomenon. The presence of hypocarbia, hyperoxia or alkalosis decreases PVR and is detrimental. They are ventilated using oxygen/air mixture, and partial pressure of oxygen is not allowed to rise very high. A higher end-tidal CO2 is maintained to achieve a higher PVR. A low afterload SVR is maintained, for an adequate stroke volume. Aggressive reduction of afterload may also be deleterious, as it attenuates the perfusion of RCA, thus decreasing the blood flow to left coronary artery. Inotropes such as dopamine, dobutamine or milrinone should be used cautiously, as they increase the consumption of myocardial oxygen, which may accentuate myocardial ischemia. Thus, patients with ALCAPA repair can be managed successfully, after understanding the pathophysiological changes.

The impact of systemic vascular resistance on the accuracy of the FloTrac/Vigileo™ system in the perioperative period of cardiac surgery: a prospective observational comparison study

FloTrac/Vigileo™ system is based on arterial pressure waveform analysis arterial pressure-based CO (APCO). Therefore, systemic vascular resistance (SVR) can influence the accuracy of APCO. The purpose of this study is to evaluate the relationship between SVR and the accuracy of APCO. We managed 50 consecutive patients in the perioperative period of cardiac surgery with FloTrac/Vigileo™ system (v. 3.02) and Swan-Ganz catheter/Vigilance™ system pulmonary artery catheter-based CO (PAC-CO) simultaneously. Continuous hemodynamic measurement using both methods was performed every 20s from the induction of anesthesia to PAC removal 4h after extubation. A total of 11,092 (intraoperative), 38,455 (postoperative, pre-extubation), and 44,235 (postoperative, post-extubation) data pairs were finally analyzed. Bland-Altman analysis revealed that in the intraoperative [postoperative pre-extubation, post-extubation] period, the bias was 0.5 [0.1, 0.0] L/min and the limits of agreement ranged from -2.4 to 3.3 [-2.2 to 2.4, -2.4 to 2.3] L/min. The percentage error was 60.3 [54.5, 48.5]%. Regression analysis of the systemic vascular resistance index (SVRI) and the bias between APCO and PAC-CO showed that the bias was positively correlated to the SVRI. Subanalysis based on SVR with Lin's concordance correlation coefficient revealed that relatively satisfactory concordance was found in the normal-SVR group (concordance correlation coefficient ρ c=0.51-0.56) regardless of vasoactive agent use. The accuracy of the FloTrac/Vigileo™ System (v. 3.02) is relatively satisfactory in the condition with normal SVR regardless of vasoactive agent use. Positive correlation between the bias and SVR can be the clue to the more effective use of FloTrac/Vigileo™ system.

Hemodynamic circulatory patterns in young patients with predominantly diastolic hypertension

To evaluate the spectrum of hemodynamic patterns in patients with isolated diastolic hypertension-predominantly diastolic hypertension, we re-analyzed a previously reported cohort of 189 non-medicated hypertensive individuals that were assessed by impedance cardiography. We selected 46 patients who were less than 50 years old and had pulse pressure less or equal than 45 mm Hg confirmed by ambulatory blood pressure monitoring. The selected cohort had a mean age of 39.7 years and was 47% men. Three distinct groups were identified: a high cardiac index (CI) “hyperdynamic” group, with normal to near normal systemic vascular resistance (SVR); an intermediate CI and SVR group; and a “vasotonic” group, with low CI and high SVR. Heart rate was similar among the three groups. Stroke volume index (SVI) was significantly higher in the hyperdynamic group (61.8, 49.7, and 39.7 mL/m2 in the high, intermediate, and low CI groups, respectively). The hyperdynamic group had greater total arterial compliance index than the vasotonic group (1.3 ± 0.3 vs 0.92 ± 0.2 mL/m2 mm Hg for high vs low CI, respectively; P < .001).In conclusion, isolated diastolic hypertension-predominantly diastolic hypertension patients can have diverse hemodynamic patterns that cannot be predicted based on peripherally measured blood pressure and heart rate alone. This hemodynamic complexity must be taken into account when considering the genetic and pathophysiologic mechanisms of hypertension.

Multivariate classification of systemic vascular resistance using photoplethysmography

Systemic vascular resistance (SVR) classification is useful for the diagnosis and prognosis of critical pathophysiological conditions, with the ability to identify patients with abnormally high or low SVR of immense clinical value. In this study, a supervised classifier, based on Bayes’ rule, is employed to classify a heterogeneous group of intensive care unit patients (N = 48) as being below (SVR < 900 dyn s cm−5), within (900 ⩽ SVR ⩽ 1200 dyn s cm−5) or above (SVR > 1200 dyn s cm−5) the clinically accepted range for normal SVR. Features derived from the finger photoplethysmogram (PPG) waveform and other routine cardiovascular measurements (heart rate and mean arterial pressure) were used as inputs to the classifier. In the construction of the classifier model, two techniques were used to approximate the class conditional probability densities-–a single Gaussian distribution model (also known as discriminant analysis) and a non-parametric model using the Parzen window kernel density estimation method. An exhaustive feature search was performed to select a feature subset that maximized the performance indicator, Cohen's kappa coefficient (κ). The Gaussian model with multiple features achieved the best overall kappa coefficient (κ = 0.57), although the results from the non-parametric model were comparable (κ = 0.51). The optimum subset in the Gaussian model consisted of PPG waveform variability features, including the low-frequency to high-frequency ratio (LF/HF) and the normalized mid-frequency power (MFNU), in addition to the PPG pulse wave features, such as pulse width, peak-to-notch time, reflection index, and notch time ratio. The classifier performed particularly well in discriminating low SVR, with a sensitivity of 85%, specificity of 86%, positive predictive value of 88% and a negative predictive value of 82%. The results highlight the feasibility of deploying a multivariate statistical approach of SVR classification in the clinical setting, simply using a non-invasive and easy-to-measure PPG waveform signal.

High‐output heart failure secondary to arteriovenous fistula

In the hemodialysis patient population, a surgically created arteriovenous fistula is the preferred vascular access option. Development of high-output heart failure may be an underappreciated complication in patients who have undergone this procedure. When a large proportion of arterial blood is shunted from the left-sided circulation to the right-sided circulation via the fistula, the increase in preload can lead to increased cardiac output. Over time, the demands of an increased workload may lead to cardiac hypertrophy and eventual heart failure. Patients may present with the usual signs of high-output heart failure including tachycardia, elevated pulse pressure, hyperkinetic precordium, and jugular venous distension. Typically, the AV fistula is quite large and is likely located in the upper arm, more proximal to the heart. Routine access flow monitoring should demonstrate blood flows (Qa) >2000 ML/min. Echocardiogram may reveal either a low or high left ventricular ejection fraction, and right-heart catheterization demonstrates an elevated cardiac output with a low to normal systemic vascular resistance. When addressing the problem of high-output heart failure, the nephrologist is faced with the dilemma of preventing progression of heart failure at the expense of loss of vascular access. Nevertheless, treatment should be directed at correcting the underlying problem by surgical banding or ligation of the fistula.

Imaging the right ventricle in pulmonary hypertension

DOI: 10.4103/0974-6013.54760 but heavily trabeculated. It is a low-pressure volume pump, working against a resting pulmonary vascular resistance (PVR), which is only one-fifteenth of normal systemic vascular resistance. The thin-wall, anterior, midline orientation, and complex geometry of the RV pose particular challenges for all imaging methods. The techniques that have been used with considerable success in PH patients are echocardiography (including 3-dimensional echocardiography and Tissue Doppler Imaging), cardiac magnetic resonance (CMR) imaging and cardiac computed tomography (CT) imaging.

Genetic modification of vascular endothelial function as therapeutic strategy in heart failure

in patients with chronic heart failure, endothelial dysfunction contributes to increased systemic vascular resistance, decreased exercise tolerance, and reduced tissue perfusion. One of the better-characterized mechanisms responsible for endothelial dysfunction is the increased production of

Haemodynamics in leptospirosis: Effects of plasmapheresis and continuous venovenous haemofiltration

Haemodynamics in leptospirosis may differ from that of sepsis because of frequently obeserved myocarditis and severe cholestatic jaundice. A haemodynamic study was therefore made in 10 patients with severe leptospirosis. All patients had pulmonary complications with a chest X-ray showing either pulmonary oedema or infiltration. Renal failure was present in nine patients. Three patterns of haemodynamics were revealed. The first pattern was observed in six patients who showed increased cardiac index, decreased systemic vascular resistance, normal pulmonary capillary wedge pressure, normal pulmonary vascular resistance and hypotension. The pattern resembled that of sepsis. The second pattern shown in two patients with haemoptysis consisted of a normal cardiac index, normal systemic vascular resistance, normal blood pressure, normal pulmonary capillary wedge pressure and increased pulmonary vascular resistance. The third pattern was observed in two patients with severe jaundice who had hypotension, a relatively low cardiac index, increased systemic vascular resistance and normal pulmonary capillary wedge pressure, and pulmonary vascular resistance. Plasmapheresis performed in two patients and continuous venovenous haemofiltration performed in two patients improved systemic haemodynamics and normalized blood pressure with a resolution of lung signs.

Systemic hemodynamics, vasoactive systems, and plasma volume in patients with severe Budd-Chiari syndrome

Budd-Chiari syndrome (BCS) causes postsinusoidal portal hypertension, which leads to complications similar to those observed in cirrhosis. However, no studies have investigated whether patients with BCS develop the hyperdynamic circulatory syndrome present in patients with cirrhosis who have portal hypertension. We evaluated systemic and cardiopulmonary hemodynamics, plasma renin activity, aldosterone and norepinephrine levels, and plasma volume in patients with BCS admitted for complications of portal hypertension. BCS patients had mean systemic and cardiopulmonary pressures and cardiac indices that were within the normal range but were significantly different from those of a group of patients with cirrhosis matched by sex, body surface, and liver function (cardiac index 3.1 +/- 0.7 vs. 4.9 +/- 1.2 L.min(-1).m(-2); P < .001; systemic vascular resistance [SVR] index, 2,189 +/- 736 vs. 1,377 +/- 422 dyne.s.cm(-5).m(-2), P < .001). Despite normal systemic vascular resistance, BCS patients had activation of the neurohumoral vasoactive systems, as evidenced by increased plasma renin activity, aldosterone and norepinephrine levels (15.0 +/- 21.5 ng/mL . h, 76.7 +/- 106.8 ng/dL, 586 +/- 868 pg/mL; respectively) and plasma volume expansion. The analysis of individual BCS patients identified that 7 of the 21 patients actually had reduced SVR index. These patients had the greatest plasma volume expansion. A significant inverse correlation between plasma volume and SVR index was observed. In conclusion, patients with BCS had activation of vasoactive neurohumoral systems and expanded plasma volume. This outcome was observed even though most of these patients did not exhibit systemic vasodilation and cardiac output was not increased, in marked contrast with what is observed in patients with cirrhosis.

急激な循環変動を認めた重症フグ中毒の１例

We present a case of puffer fish poisoning that developed marked changes in hemodynamic status. A 42-year-old man recognized numbness in his fingers and lips 3 hours after tasting pieces of puffer fish liver, and was admitted to our emergency center with dyspnea. Since spontaneous breathing weakened after admission, mechanical ventilation was started. One hour after admission, his blood pressure gradually decreased to 60mmHg with a pulse rate of 60/min. Rapid infusion and dopamin administration successfully elevated and stabilized his hemodynamics. However, his blood pressure increased to 235mmHg accompanied with remarkable sweating 6 hours later. Although dopamin was discontinued, his blood pressure re-elevated and required nicardipine to decrease and stabilize it. Thirty-two hours after admission, spontaneous breathing resumed and he was extubated. Analyses of his hemodynamics using a Swan-Ganz catheter revealed that the cardiac index decreased to 1.9l/min/m2 with a normal systemic vascular resistance (SVRI 1, 780dynes/sec/cm-5/m2) when his blood pressure decreased. On the other hand, elevation of blood pressure was accompanied with increases of both cardiac index and vascular resistance. The extreme changes in hemodynamics in this case were thought to be caused by the time course of impairment and recovery of the peripheral sympathetic nerves induced by the tetrodotoxin in puffer fish.

Systemic Inflammatory Response Syndrome (SIRS) Following Emergency Cardiopulmonary Bypass: A Case Report and Literature Review

A complication of emergency resuscitation is the development of the Systemic Inflammatory Response Syndrome (SIRS). In the past, this has been identified as multiple organ failure, with symptoms similar to sepsis. The hallmark of this syndrome is peripheral vasodilation, which is associated with a breakdown of capillary membranes and the accumulation of excess interstitial fluid. This case report discusses the development of SIRS in a patient following emergency cardiopulmonary bypass (CPB). The patient was a 53 year old male with significant left main coronary artery disease who developed sudden bradycardia and hypotension in the operating room and was emergently placed on cardiopulmonary bypass. During CPB, the patient was peripherally vasodilated, and required continuous alpha-adrenergic support to maintain normal systemic vascular resistance. In addition, metabolic acidosis was present despite high flow rates, high hematocrit, addition of colloids, and hemoconcentration. Despite excellent neurological and myocardial recovery following surgery, the patient died one week later in renal and hepatic failure. Several mechanisms for the development of this syndrome have been hypothesized. One of these theories is that the ischemic injury in the gastrointestinal tract disturbs the gut barrier function and allows enteric bacterial endotoxins to pass into the circulation producing sepsislike symptoms. Other theories relate to the release patterns of cytokines associated with CPB. These mechanisms and the treatment of SIRS with new pharmacological agents and perfusion techniques are reviewed.

Haemodynamic patterns in patients with scorpion envenomation

ObjectiveTo study cardiovascular haemodynamics following scorpion envenomation.SettingIntensive care unit of a university hospital.PatientsEight patients with Indian red scorpion (Mesobuthus tamulus) stings.InterventionCaptopril (6.25 to 12.5 mg orally) every 30 minutes until...

Are patients receiving amiodarone at increased risk for cardiac operations?

Amiodarone therapy has been implicated as a risk factor for cardiothoracic surgical procedures. In patients undergoing map-guided surgical procedures for the treatment of ventricular tachycardia, we compared the perioperative course of those receiving long-term amiodarone therapy (n = 36) versus that in those not receiving the drug (n = 31). The two groups were similar with respect to age, sex, presenting symptoms, functional class, extent of coronary artery disease, presence of a ventricular aneurysm, technique of ventricular tachycardia abration, cross-clamp or pump time, the number of vessels grafted, the operative fluid balance, and a need for intraaortic balloon pump or inotropic agent support. In 5 patients receiving amiodarone, epinephrine was required to maintain a normal systemic vascular resistance and adequate arterial pressure. Postoperatively, 6 patients (17%) on amiodarone therapy suffered acute respiratory failure. In spite of aggressive therapy, 3 of these patients died. Only 1 patient not receiving amiodarone died of a stroke. We conclude that amiodarone therapy in patients undergoing open heart operations is associated with an increased risk of severe pulmonary complications ( p = 0.03 by Fisher's exact test). Amiodarone therapy should be withheld in patients with ventricular tachycardia until they have been assessed as candidates for possible surgical intervention.

The central hemodynamics of severe preeclampsia

Swan-Ganz hemodynamic monitoring in 49 antepartum patients with severe preeclampsia revealed a variable hemodynamic profile. The majority of patients had normal left ventricular filling pressure (8.4 +/- 0.2 mm Hg), normal to high cardiac index (4.4 +/- 0.1 L.min-1.m2), and upper normal to moderately elevated systemic vascular resistance (1226 +/- 37 dynes.sec.cm-5). Eight patients had pulmonary edema and their findings included high wedge pressure (18 +/- 1 mm Hg), upper normal to high cardiac index (4.9 +/- 0.5 L.min-1.m2), and normal systemic vascular resistance (964 +/- 50 dynes.sec.cm-5). Left ventricular function was hyperdynamic in 73% of the 49 patients. Patients with chronic hypertension and superimposed preeclampsia were hemodynamically indistinguishable from patients with preeclampsia alone. We conclude that, in general, preeclampsia is a high cardiac output state associated with an inappropriately high peripheral resistance. The normal wedge and central venous pressures suggest central redistribution of intravascular volume if the generally accepted reports of decreased plasma volume in preeclampsia are correct.

Circulatory Congestion in Obese Hypertensive Women

We describe four obese, chronically hypertensive women presenting with antepartum pulmonary edema in whom invasive hemodynamic monitoring showed elevated wedge pressure, normal to high cardiac index, and normal systemic vascular resistance. Echocardiography revealed large chambers, thick walls, and increased left ventricular mass with normal systolic but abnormal diastolic function. These findings are indicative of intrinsic volume overload occurring in the presence of impaired left ventricular relaxation, a combination resulting in high filling pressures and pulmonary congestion. Diuretic therapy is indicated in this subset of patients, who could not be recognized by the usual clinical parameters such as history and physical examination, chest x-ray, and arterial blood gas.

Endotoxin and tumor necrosis factor challenges in dogs simulate the cardiovascular profile of human septic shock.

Survivors of both human and animal bacterial shock develop a characteristic pattern of progressive changes in cardiovascular function over a period of 7-10 d. In this present study, we examined whether endotoxin (a product of Gram-negative bacteria) or TNF (a cytokine released from macrophages) could reproduce the same complex cardiovascular changes observed in septic shock over a period of 7-10 d. To test this hypothesis, we implanted a thrombin-fibrin clot containing purified endotoxin from E. coli into the peritoneal cavity of eight dogs, and infused TNF into eight different dogs. Over the next 10 d, serial simultaneous heart scans and thermodilution cardiac outputs were performed in these awake nonsedated animals. By day 2 after challenge with either endotoxin or TNF, animals developed a decrease (p less than 0.05) in both mean arterial pressure and left ventricular ejection fraction. With fluid resuscitation, animals manifested left ventricular dilatation (increased [p less than 0.05] end diastolic volume index), increased or normal cardiac index, and decreased or normal systemic vascular resistance index. In surviving animals, these changes returned to normal with 7-10 d. The time course of these changes was concordant (p less than 0.05) with that previously described in a canine model of septic shock using viable bacteria. During the 10-d study, control animals receiving sterile clots or heat-inactivated TNF had not significant changes in hemodynamics. The results from this canine model demonstrate that either endotoxin or TNF alone can produce many of the same hemodynamic abnormalities seen in human septic shock and in a canine septic shock model induced by live bacteria. These findings support the hypothesis that the action of endogenous mediators (TNF) responding to bacterial products (endotoxin) is the common pathway that produces the serial cardiovascular changes found in septic shock.

Effects of Continuous Arteriovenous Hemofiltration on Cardiopulmonary Abnormalities during Anesthesia for Orthotopic Liver Transplantation

Orthotopic liver transplantation (OLT) often involves large blood loss and replacement, as well as administration of large amounts of blood products to correct coagulation defects. Renal free water excretion is often impaired in end-stage liver disease and not responsive to routine diuretic therapy, predisposing these patients to accumulation of extravascular lung water. The effects of the intraoperative use of continuous arteriovenous hemofiltration (CAVH) on cardiopulmonary and oxygen transport variables were studied in ten patients during and 24 hours after OLT. CAVH prevented increases in pulmonary shunt fraction while decreasing PEEP and FIO2 requirements. Pulmonary compliance was significantly higher after operation in patients receiving CAVH. Before surgical dissection, hemodynamic effects of CAVH were minimal. Postoperatively, patients having CAVH had lower cardiac filling pressures and more normal systemic vascular resistance than did patients not having CAVH. These data suggest that CAVH may be a useful intraoperative technique for patients with impaired renal function undergoing liver transplantation.