PICCO在老年髋关节手术麻醉及血流动力学优化中的应用

目的:探讨脉搏指示持续心输出量(pulse induced contour crdic output,PICCO)技术在老年髋关节手术麻醉及血流动力学优化中的临床应用。方法:将106例老年髋关节手术患者随机分成2组,每组各53例。常规组放置中心静脉导管和动脉导管,PICCO组放置PICCO,检测平均动脉压(mean arterial pressure,MAP)、中心静脉压(central venous pressure,CVP)、心率(heart rate,HR)、心指数(cardiac index,CI)、血管外肺水指数(extravascular lung water index,ELWI)、胸腔内血容量指数(intrathoracic blood volume index,ITBI)及肺血管通透性指数(pulmonary vascular permeability index,PVPI)等血流动力学参数。记录PICCO组术中各指标的变化,比较分析两组术后前3天液体输入量,术后并发症发生情况。结果:与T0时点比较,PICCO组T1时点的MAP、CVP、CI、ITBI明显降低,HR明显升高(P0.05);T2时点MAP、CVP、CI较T1明显升高,HR明显下降(P0.05);PICCO组T2时刻各血流动力学指标均明显优于常规组(P0.05)。PICCO组术后前3天的液体入量明显少于常规组(P0.05);ELWI与PVPI、ITBI、液体入量均呈高度正相关(P0.05)。且PICCO组术后肺部感染及心血管并发症的发生率也较常规组明显降低(P0.05)。结论:PICCO监测可准确反映血流动力学状态参数,指导临床麻醉和围术期液体管理,减少术中术后不良并发症,改善患者预后。     

Electrolyte and plasma enzyme analyses during large-volume liposuction

Substantial fluid shifts occur during liposuction as wetting solution is infiltrated subcutaneously and fat is evacuated, causing potential electrolyte imbalances. In the porcine model for large-volume liposuction, plasma aspartate aminotransferase and alanine transaminase levels were elevated following liposuction. These results raised concerns for possible mechanical injury and/or lidocaine-induced hepatocellular toxicity in a clinical setting. The first objective of this human model study was to explore the effect of the liposuction procedure on electrolyte balance. The second objective was to determine whether elevated plasma aminotransferase levels were observed subsequent to large-volume liposuction. Five female volunteers underwent three-stage, ultrasound-assisted liposuction. Blood samples were collected perioperatively. Plasma levels of sodium, potassium, venous carbon dioxide, blood urea nitrogen, chloride, and creatinine were determined. Liver function analyte levels were measured, including albumin, total protein, aspartate aminotransferase, and alanine transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, and total bilirubin. To further define intracellular enzyme release, creatine kinase levels were measured. Mild hyponatremia was evident postoperatively (134 to 136 mmol/liter) in four patients. Hypokalemia was evident intraoperatively in all subjects (mean +/- SEM; 3.3 +/- 0.16 mmol/liter; range, 3.0 to 3.4 mmol/liter). Hypoalbuminemia and hypoproteinemia were observed throughout the study (baseline: 2.9 +/- 0.2 g/dl; range, 2.6 to 3.5 g/dl), decreasing to 10 to 40 percent 24 hours postoperatively (2.0 +/- 0.2 g/dl; range, 1.7 to 2.1 g/dl). Aspartate aminotransferase, alanine transaminase, and creatine kinase levels were significantly elevated after the procedure (190 +/- 47.1 U/liter, 50 +/- 7.7 U/liter, and 11,219 +/- 2556.7 U/liter, respectively) (p < 0.01). Release of antidiuretic hormone and even mildly hypotonic intravenous fluid infiltration have long been known to cause hyponatremia postoperatively. Intraoperative hypokalemia is associated with hypocarbia and respiratory alkalosis and the elevated epinephrine levels observed in the concurrent study. Factors having the greatest initial impact on diminished serum albumin and protein levels postoperatively are redistribution and hemodilution. Subsequent diminished viscosity may significantly affect postoperative hemodynamics. Elevated aspartate aminotransferase, alanine transaminase, and creatine kinase levels are associated with skeletal muscle injury, adipocyte lysis, and/or hepatic damage. Therefore, tissue injury is associated with large-volume liposuction as observed in several cellularly released enzymes. Future clinical studies are required to determine the degree of injury and specific tissues that are damaged or sensitive to mechanical trauma and/or drugs used in large-volume liposuction.     

Atrial natriuretic peptide correlates with pulmonary arterial pressure and cardiac output

Correlations between plasma atrial natriuretic polypeptide (ANP) levels and hemodynamic parameters were studied in the central circulation of 12 patients with angina pectoris. The average plasma ANP level determined in the aorta was found to be 619 +/- 140 pg/ml. The plasma ANP levels showed a significant positive correlation with mean pulmonary arterial (PA) pressure, right ventricular pressure, and with cardiac index. In contrast, there was no significant correlation between plasma ANP levels and other hemodynamic variables including atrial pressure. These results suggest that hemodynamics other than the atrial pressure may have some role in modulating ANP secretion in certain pathological states.     

Pharmacokinetics and safety of epinephrine use in liposuction

Patients are routinely exposed to high-dose epinephrine infiltration during large-volume liposuction. Because of the serious cardiovascular side-effect profile of catecholamine overdose, the authors examined the safety of larger-volume liposuction by assessing epinephrine pharmacokinetics. Five female volunteers with American Society of Anesthesiologists physical status of I or II, aged 29 to 40 years and weighing 75.9 to 95 kg, underwent liposuction. The wetting solution contained 7.3 mg (SEM, 0.7 mg) of epinephrine, corresponding to 0.09 mg/kg (0.04 mg/kg). Total plasma epinephrine and norepinephrine concentrations were assessed by high-performance liquid chromatography. Approximate exogenous epinephrine absorption was calculated after correction for estimated endogenous epinephrine production. Pharmacokinetic assessments were performed using standard equations. The total plasma epinephrine peak occurred at the final intraoperative reading (5 hours after induction) and was 323 pg/ml (24.8 pg/ml), three to four times maximum baseline resting levels. The norepinephrine level was slightly elevated throughout the study period, with a reversal of the normal epinephrine/norepinephrine ratio (<0.5:1) demonstrated intraoperatively (>5:1). Estimated time to peak exogenous epinephrine level ranged from 1 to 4 hours from the start of infiltration. Area under the plasma concentration versus time curve was approximately 2089 to 2610 pg x hour/ml. Peak exogenous epinephrine concentration was estimated to be 286 to 335 pg/ml. Clearance was 764,508 ml/hour and volume of distribution was 0.4 liter/kg (0.006 liter/kg). Total absorbed epinephrine was estimated, 1.8 mg to 2.2 mg, equivalent to 25 to 32 percent of the infiltrated dose. The reversal of the normal epinephrine/norepinephrine ratio and the fact that norepinephrine levels were within normal range implied that the majority of plasma epinephrine measured was exogenously infiltrated and not endogenously synthesized. On the basis of these observations, pharmacokinetic analyses were performed. Although unequivocal toxic epinephrine levels were not demonstrated, epinephrine peaks were three to four times the maximum observed in normal resting patients. Peak levels were comparable to those observed during major physiologic stresses, such as exercising to exhaustion, open abdominal surgery, or cross-clamping the aorta during surgical repair. Furthermore, epinephrine has been associated with myocardial infarction, arrhythmias, and fatal asystole in susceptible patients at these levels. Patients should be carefully screened for clinical evidence of hemodynamic and cardiac pathology before larger-volume liposuction is undertaken, as it may result in unnecessary high risk for patients who have preexisting cardiovascular disorders. Healthy American Society of Anesthesiologists physical status I or II patients should have sufficient cardiac reserve to tolerate these catecholamine levels.     

Effects of spinal anesthesia on response to main pulmonary arterial distension

Nonocclusive main pulmonary arterial distension produces peripheral pulmonary hypertension. The mechanism of this response is unknown. The effects of total spinal anesthesia on the response were studied in halothane-anesthetized dogs. Before total spinal anesthesia, main pulmonary arterial balloon inflation increased pulmonary arterial pressure and resistance without affecting systemic hemodynamic variables. Both right and left pulmonary arterial pressures were monitored to exclude unilateral obstruction with main pulmonary arterial balloon inflation. Total spinal anesthesia decreased cardiac output and systemic arterial pressures. After total spinal anesthesia, main pulmonary arterial distension still increased pulmonary arterial pressure and resistance. Right atrial pacing, discontinuation of halothane anesthesia, and norepinephrine infusion during total spinal anesthesia partially reversed the hemodynamic changes caused by total spinal anesthesia. The percent increase in pulmonary vascular resistance due to main pulmonary arterial distension was similar before total spinal anesthesia and during all experimental conditions during total spinal anesthesia. The pulmonary hypertensive response is therefore not dependent on central synaptic connections.     

Factors that determine the hemodynamic response to inhalation anesthetics

The hemodynamic response to inhalation anesthesia is influenced by three factors: 1) the specific drug, 2) the dose, and 3) individual characteristics of the subject. To investigate the importance of these factors on the cardiovascular response, we administered five doses [0, 0.5, 1.0, 1.5, and 2.0 minimum alveolar concentration (MAC)] of enflurane, halothane, and isoflurane to each of six dogs. Twelve hemodynamic variables were measured. For all variables, a change in the dose of each drug produced a consistent effect in each dog. Increases in dose resulted in significant decreases in seven variables [left ventricular ejection fraction, cardiac index (CI), stroke volume index (SVI), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), left ventricular stroke work index (LVSWI), and heart rate (HR)] and a significant increase in one variable [central venous pressure (CVP)]. In contrast, the response of individual dogs to different drugs was not consistent. For seven variables [MAP, MPAP, LVSWI, CVP, pulmonary capillary wedge pressure (PCWP), end-diastolic volume index (EDVI), and end-systolic volume index (ESVI)], a significant difference in the responses of a dog to two drugs was greater than zero, whereas a significant difference in the response of at least one other dog to the same two drugs was less than zero (discordant dog-drug interactions). Thus, in contrast to the consistency of the cardiovascular response to changes in dose, the hemodynamic response to different drugs was inconsistent among dogs. We also studied the effect of fluid challenge on hemodynamic response at 1.5 or 2.0 MAC of the three drugs given to each dog.(ABSTRACT TRUNCATED AT 250 WORDS)     

Perioperative management of cosmetic liposuction

Recent qualms about the safety of aesthetic lipoplasty may be attributable more to support system flaws than to technical process deficiencies. The authors here focus on perfunctory patient monitoring when sedative or analgesic drugs are given, cavalier infiltration of mega-dose lidocaine, cursory intraoperative patient observation by team members with conflicting responsibilities, anesthesia providers unfamiliar with the unique surgical physiology of liposuction, hurried-discharge policies that virtually ignore the residual depressant effects of sedatives and analgesics, and compressive dressings that impair postoperative chest-wall expansion and venous return. Whereas pulmonary embolism remains the leading process cause of morbidity from liposuction, complications from austere resource allocation to dedicated patient monitoring should be largely preventable. Not all lipoplasties require an anesthesia provider but-when heavy sedation, mega-dose lidocaine, or both, are projected-a trained team member dedicated exclusively to patient safety and comfort should be a minimum patient care standard. The potential role of lidocaine cardiotoxicity in tumescent anesthesia is widely underappreciated and that of hypothermia goes mostly unrecognized. These, plus largely preventable or potentially correctable perioperative events such as pulmonary edema, fluid imbalance, or improperly administered sedative and analgesic drugs, demand upgrading and expansion of monitoring, resuscitative, and recuperative facilities in physician offices. In fact, ASPS guidelines urge that anesthesia services be engaged for dedicated patient care whenever "major" liposuction or conscious sedation is projected, because liposuction is neither as benign nor as simple a procedure as heretofore reputed. To assess objectively the operative and anesthetic risk of obesity, document body mass index for the preoperative record; morbid obesity (body mass index >/= 35.0), for instance, is a known risk multiplier for sedatives and analgesics. Other system issues such as the dynamic profile of high-dose lidocaine pharmacokinetics, the deportation of fat globules in the bloodstream, and the incidence of intraoperative hypothermia remain as unresolved topics for interdisciplinary, multi-institutional clinical research.     

Cardiopulmonary effects of hemorrhagic shock in splenic autotransplanted pigs: a new surgical model

The spleen is an important organ for hemodynamic compensation during hemorrhagic shock. The aim of the study was to compare the hemodynamic and metabolic responses of sham-operated pigs with intact spleen, splenectomized pigs, and splenic autotransplanted pigs during hemorrhagic shock. Hemorrhagic shock was induced by 30% total blood volume bleed in sham-operated, splenectomized and splenic autotransplanted pigs (n = 20). Cardiopulmonary and metabolic variables were measured before, immediately after, and at 20, 60 and 100 minutes after hemorrhage. Upon hemorrhagic shock induction, body temperature, mean arterial pressure, mean pulmonary arterial pressure, cardiac output, cardiac index and oxygen delivery decreased, while lactate and shock index increased. Hemoglobin and hematocrit were significantly lower in the splenectomized and splenic autotransplant groups as compared with the control group at 60 and 100 minutes after hemorrhage (p < 0.05). Unlike intact spleen, splenic autotransplant could not improve hemodynamic parameters in hemorrhagic shock in pigs. In comparison to mice, rats or dogs, this species could be an interesting investigation model to test new surgical procedures during splenic related hemorrhagic shock, with potential applications in human medicine.     

丙泊酚与异氟醚麻醉对妇科腹腔镜手术患者血流动力学及应激反应的影响

目的:探究丙泊酚与异氟醚麻醉对接受妇科腹腔镜手术的患者应激激素以及血流动力学的影响。方法:选取我院妇科收治的需要进行腹腔镜手术的患者90例,根据麻醉用药不同,将其分为丙泊酚组、异氟醚组及实验组,每组各30例。观测患者不同时段去甲肾上腺素(NE)、肾上腺素(E)、皮质醇(COS)的浓度及心率、平均动脉压、呼吸频率、血氧饱和度等血流动力学参数的变化情况。结果:三组患者麻醉前及气腹20 min的去甲肾上腺素、肾上腺素以及皮质醇含量比较均无显著差异(P0.05);气腹前,实验组患者去甲肾上腺素含量显著低于丙泊酚组及异氟醚组(P0.05);放气10 min,实验组患者肾上腺水平显著高于丙泊酚组及异氟醚组(P0.05);三组患者麻醉前及气腹前的心率、平均动脉压、呼吸以及血氧饱和度比较均无显著差异(P0.05);气腹20 min,实验组患者的心率、平均动脉压、呼吸显著优于丙泊酚组及异氟醚组(P0.05);术后放气10 min,实验组患者的心率、平均动脉压、呼吸显著优于丙泊酚组及异氟醚组(P0.05);实验组患者术后出现恶心、呕吐等症状显著优于丙泊酚组及异氟醚组(P0.05)。结论:丙泊酚复合异氟醚可有效改善接受妇科腹腔镜手术的患者麻醉期间的应激反应和血流动力学,患者术后恶心、呕吐等不良反应少,值得推广使用。     

Reference cardiopulmonary values in normal dogs

The purpose of this project was to collate canine cardiopulmonary measurements from published and unpublished studies in our laboratory in 97 instrumented, unsedated, normovolemic dogs. Body weight; arterial and mixed-venous pH and blood gases; mean arterial, pulmonary arterial, pulmonary artery occlusion, and central venous blood pressures; cardiac output; heart rate; hemoglobin; and core temperature were measured. Body surface area; bicarbonate concentration; base deficit; cardiac index; stroke volume index, systemic and pulmonary vascular resistance indices; left and right cardiac work indices; alveolar partial pressure of oxygen (pO2) ; alveolar-arterial pO2 gradient (A-apO2); arterial, mixed-venous, and pulmonary capillary oxygen content; oxygen delivery; oxygen consumption; oxygen extraction; venous admixture; arterial and mixed-venous blood CO2 contents; and CO2 production were calculated. In the 97 normal, resting dogs, mean arterial and mixed-venous pH were 7.38 and 7.36, respectively; partial pressure of carbon dioxide (pCO2), 40.2 and 44.1 mm Hg, respectively; base-deficit, -2.1 and -1.9 mEq/liter, respectively; pO2, 99.5 and 49.3 mm Hg, respectively; oxygen content, 17.8 and 14.2 ml/dl, respectively; A-a pO2 was 6.3 mm Hg; and venous admixture was 3.6%. The mean arterial blood pressure (ABPm), mean pulmonary arterial blood pressure (PAPm), pulmonary artery occlusion pressure (PAOP) were 103, 14, and 5.5 mm Hg, respectively; heart rate was 87 beats/min; cardiac index (CI) was 4.42 liters/min/m2; systemic and pulmonary vascular resistances were 1931 and 194 dynes.sec.cm-5, respectively; oxygen delivery, consumption and extraction were 790 and 164 ml/min/m2 and 20.5%, respectively. This study represents a collation of cardiopulmonary values obtained from a large number of dogs (97) from a single laboratory using the same measurement techniques.     

Cardiovascular and adrenal medullo-sympathetic reactions to acute tobacco poisoning

We studied the effects after cigarette quicksmoking in 15 subjects on plasma catecholamines levels (epinephrine and norepinephrine), on heart rate and arterial pressure. Smoking-associated increments in mean plasma norepinephrine and epinephrine as well as in heart rate and arterial pressure were demonstrated. The lack of correlation between the increase of the adrenergic system activity and this of the hemodynamic parameters can be explained by their own different characteristics.     

Improvements in cardiovascular risk profile with large-volume liposuction: a pilot study

In this study, the authors investigated the physiologic effects of the altered body composition that results from surgical removal of large amounts of subcutaneous adipose tissue. Fourteen women with body mass indexes of greater than > 27 kg/m2 underwent measurements of fasting plasma insulin, triglycerides, cholesterol, body composition by dual-energy x-ray absorptiometry (DXA), resting energy expenditure, and blood pressure before and after undergoing large-volume ultrasound-assisted liposuction.There were no significant intraoperative complications. Body weight had decreased by 5.1 kg (p < 0.0001) by 6 weeks after liposuction, with an additional 1.3-kg weight loss (p < 0.05) observed between 6 weeks and 4 months after surgery, for a total weight loss of 6.5 kg (p < 0.00006). Body mass index decreased from (mean +/- SEM) 28.8 +/- 2.3 to 26.8 +/- 1.5 kg/m2 (p < 0.0001). This change in body weight was primarily the result of decreases in body fat mass: as assessed by DXA, lean body mass did not change (43.8 +/- 3.1 kg to 43.4 +/- 3.6 kg, p = 0.80), whereas DXA total body fat mass decreased from 35.7 +/- 6.3 to 30.1 +/- 6.5 kg (p < 0.0001). There were significant decreases in fasting plasma insulin levels (14.9 +/- 6.5 mIU/ml before liposuction versus 7.2 +/- 3.2 mIU/ml 4 months after liposuction, p < 0.007), and systolic blood pressure (132.1 +/- 7.2 versus 120.5 +/- 7.8 mmHg, p < 0.0002). Total cholesterol, high-density lipoprotein cholesterol, plasma triglycerides, and resting energy expenditure values were not significantly altered after liposuction.In conclusion, over a 4-month period, large-volume liposuction decreased weight, body fat mass, systolic blood pressure, and fasting insulin levels without detrimental effects on lean body mass, bone mass, resting energy expenditure, or lipid profiles. Should these improvements be maintained over time, liposuction may prove to be a valuable tool for reducing the comorbid conditions associated with obesity.     

Haemodynamic effects of intravenous morphine in patients with acute myocardial infarction complicated by severe left ventricular failure.

The haemodynamic effects of intravenous morphine sulphate (0.2 mg/kg body weight) were measured in 10 patients with acute myocardial infarction complicated by severe left ventricular failure. Fifteen minutes after morphine injection there was a significant fall in mean heart rate (from 109 to 101 beats/min) and mean systemic arterial pressure (from 80 to 65 mm HG), and a small fall in mean cardiac index (from 2.4 to 2.21/min/m2). Haemodynamic changes at 45 minutes were similar. Neither stroke index nor indirect left ventricular filling pressure (measured as pulmonary artery end-diastolic pressure) were consistently improved 15 or 45 minutes after injection. The useful action of morphine in relieving distressing cardiac dyspnoea is not adequately explained by systemic venous blood pooling. These results suggest that the effects of morphine on the central nervous system are more important.     

Effects of sympathetic stimulation during cooling on hypothermic as well as posthypothermic hemodynamic function

This experimental study was performed to explore hemodynamic effects of a moderate dose epinephrine (Epi) during hypothermia and to test the hypothesis whether sympathetic stimulation during cooling affects myocardial function following rewarming. Two groups of male Wistar rats (each, n=7) were cooled to 15 degrees C, maintained at this temperature for 1 h, and then rewarmed. Group 1 received 1 microg/min Epi, i.v., for 1 h during cooling to 28 degrees C, a dose known to elevate cardiac output (CO) by approximately 25% at 37 degrees C. Group 2 served a saline solution control. At 37 degrees C, Epi infusion elevated CO, left ventricular systolic pressure, maximum rate of left ventricle pressure rise, and mean arterial pressure. During cooling to 28 degrees C, these variables, with the exception of mean arterial pressure, decreased in parallel to those in the saline solution group. In contrast, in the Epi group, mean arterial pressure remained increased and total peripheral resistance was significantly elevated at 28 degrees C. Compared with corresponding prehypothermic values, most hemodynamic variables were lowered after 1 h at 15 degrees C in both groups (except for stroke volume). After rewarming, alterations in hemodynamic variables in the Epi-treated group were more prominent than in saline solution controls. Thus, before cooling, continuous Epi infusion predominantly stimulates myocardial mechanical function, materialized as elevation of CO, left ventricular systolic pressure, and maximum rate of left ventricle pressure rise. Cooling, on the other hand, apparently eradicates central hemodynamic effects of Epi and during stable hypothermia, elevation of peripheral vascular vasopressor effects seem to take over. In contrast to temperature-matched, non-Epi stimulated control rats, a significant depression of myocardial mechanical function occurs during rewarming following a moderate sympathetic stimulus during initial cooling.     

Theoretical analysis of rest and exercise hemodynamics in patients with total cavopulmonary connection

The objective of this study was to determine the impact of a total cavopulmonary connection on the main hemodynamic quantities, both at rest and during exercise, when compared with normal biventricular circulation. The analysis was performed by means of a mathematical model of the cardiovascular system. The model incorporates the main parameters of systemic and pulmonary circulation, the pulsating heart, and the action of arterial and cardiopulmonary baroreflex mechanisms. Furthermore, the effect of changes in intrathoracic pressure on venous return is also incorporated. Finally, the response to moderate dynamic exercise is simulated, including the effect of a central command, local metabolic vasodilation, and the "muscle pump" mechanism. Simulations of resting conditions indicate that the action of baroreflex regulatory mechanisms alone can only partially compensate for the absence of the right heart. Cardiac output and mean systemic arterial pressure at rest show a large decrease compared with the normal subject. More acceptable hemodynamic quantity values are obtained by combining the action of regulatory mechanisms with a chronic change in parameters affecting mean filling pressure. With such changes assumed, simulations of the response to moderate exercise show that univentricular circulation exhibits a poor capacity to increase cardiac output and to sustain aerobic metabolism, especially when the oxygen consumption rate is increased above 1.2-1.3 l/min. The model ascribes the poor response to exercise in these patients to the incapacity to sustain venous return caused by the high resistance to venous return and/or to exhaustion of volume compensation reserve.     

The respiratory change in preejection period: a new method to predict fluid responsiveness.

The accuracy and clinical utility of preload indexes as bedside indicators of fluid responsiveness in patients after cardiac surgery is controversial. This study evaluates whether respiratory changes (Delta) in the preejection period (PEP; DeltaPEP) predict fluid responsiveness in mechanically ventilated patients. Sixteen postcoronary artery bypass surgery patients, deeply sedated under mechanical ventilation, were enrolled. PEP was defined as the time interval between the beginning of the Q wave on the electrocardiogram and the upstroke of the radial arterial pressure. DeltaPEP (%) was defined as the difference between expiratory and inspiratory PEP measured over one respiratory cycle. We also measured cardiac output, stroke volume index, right atrial pressure, pulmonary arterial occlusion pressure, respiratory change in pulse pressure, systolic pressure variation, and the Deltadown component of SPV. Data were measured without positive end-expiratory pressure (PEEP) and after application of a PEEP of 10 cmH2O (PEEP10). When PEEP10 induced a decrease of >15% in mean arterial pressure value, then measurements were re-performed before and after volume expansion. Volume loading was done in eight patients. Right atrial pressure and pulmonary arterial occlusion pressure before volume expansion did not correlate with the change in stroke volume index after the fluid challenge. Systolic pressure variation, DeltaPEP, Deltadown, and change in pulse pressure before volume expansion correlated with stroke volume index change after fluid challenge (r2 = 0.52, 0.57, 0.68, and 0.83, respectively). In deeply sedated, mechanically ventilated patients after cardiac surgery, DeltaPEP, a new method, can be used to predict fluid responsiveness and hemodynamic response to PEEP10.     

Comparison of haemodynamic responses to dopamine and salbutamol in severe cardiogenic shock complicating acute myocardial infarction.

Twelve patients with severe persistent cardiogenic shock complicating acute myocardial infarction underwent single crossover treatment with intravenous dopamine and salbutamol to determine the more beneficial therapy. Salbutamol (10 to 40 microgram/min) reduced systemic vascular resistance and progressively increased both cardiac index and stroke index. Heart rate increased from 95 to 104 beats/min. Changes in mean arterial pressure and pulmonary artery end-diastolic pressure were small and insignificant. Dopamine infusion at rates of 200 and 400 micrograms/min also increased cardiac index and stroke index. Systemic vascular resistance fell slightly but mean arterial pressure rose from 57 to 65 mm Hg. Heart rate increased from 95 to 105 beats/min. Changes in pulmonary artery end-diastolic pressure were again small and insignificant. Dopamine infusion at 800 micrograms/min caused an appreciable increase in systemic vascular resistance; a further increment in mean arterial pressure was observed, though cardiac index fell slightly. Heart rate and pulmonary artery end-diastolic pressure rose steeply. Salbutamol, a vasodilator, increased cardiac output in patients with cardiogenic shock complicating acute myocardial infarction but did not influence blood pressure. If correction of hypotension is essential dopamine in low doses may be the preferred agent. Doses of 800 microgram/min, which is within the therapeutic range, worsen other manifestations of left ventricular dysfunction.     

Determination of cardiac output and other reference physiology parameters in lightly anesthetized dogs

1. Cardiac output; arterial, pulmonary artery, central venous and pulmonary wedge pressures; heart rate, hematocrit, and plasma sodium and potassium; arterial and mixed venous blood gases; and respiratory rates were measured in 45 mixed sex, non-pregnant, clinically normal mongrel dogs of 8-30 kilograms body weight following light anesthesia with halothane/50% N20-02. 2. Arithmetic means and standard deviations were calculated to develop tables of reference values. 3. Mean measured cardiac outputs were found to be 31-59% higher in these dogs than the values indicated by published standards; cardiac indices were 30-44% higher; heart rates were 16-30% lower; calculated stroke volumes were 60-112% greater; and total peripheral resistances were 35-57% less than the standard published values. 4. All other measured or calculated parameters fell within previously published canine or human reference limits.     

Effects of epinephrine on resisitive and compliant properties of the canine vasculature.

The peripheral circulation of 22 anesthetized dogs was separated into three parallel regions, where the outflow from each region could be measured and both outflow and inflow pressures could be controlled. We were thus able to estimate arterial and venous resistance and venous compliance for each region. The pressure dependency of these parameters was determined before and during continuous infusion of epinephrine (3 mug-kg-1 min-1). Epinephrine increased the arterial resistance in all regions but did so in such manner as to increase the fraction of cardiac output perfusing the splanchnic region. The venous resistances were all elevated by epinephrine and showed a greater pressure dependency than during control. Systemic venous complicance was found to be pressure dependent during both control and epinephrine administration, decreasing by nearly 50% from the lowest to the highest venous pressures (4-12 mmHg) investigated. Splanchnic compliance was found to comprise nearly half the total systemic compliance. Results were interpreted using an extension of the parallel compartment model of the peripheral circulation described by Caldini, Permutt, Waddell, and Riley (2).     

Heparin reversal by protamine in humans--complement, prostaglandins, blood cells, and hemodynamics.

Fourteen noncardiac surgical patients received heparin (10,000 IU), which was neutralized by 100 mg protamine injected within 2 min during steady-state anesthesia. After protamine application, plasma complement C3a, thromboxane B2 (TxB2), prostaglandin F2 alpha (PGF2 alpha) and KH2PGF2 alpha increased significantly, whereas prostacyclin (6-keto-PGF2 alpha) levels did not change. This mediator response was associated with transient leukopenia and thrombocytopenia. Arterial pressure, pulmonary arterial pressure, and transpulmonary pressure gradient increased significantly. Heart rate, cardiac output, pulmonary capillary wedge pressure, and arterial PO2 remained constant. Positive correlations of plasma C3a were observed with pulmonary leukosequestration and plasma TxB2. Inverse correlations of C3a were noted with the counts of leukocytes and of platelets. A positive correlation was found between TxB2 and pulmonary arterial pressure. Our results indicate that marked activation of the complement system and the cyclooxygenase pathway is common after heparin reversal by protamine in anesthetized patients. This is in contrast to previous human studies performed after cardiopulmonary bypass but agrees well with results obtained in animal experiments. The mediator response in our patients, however, was not accompanied by hemodynamic instability, suggesting appropriate compensatory mechanisms.