Clinical application of ventricular end-systolic elastance and the ventricular pressure-volume diagram.

The ability to clinically assess myocardial contractility in a load-independent fashion facilitates the selection of appropriate inotropes, when needed, during shock resuscitation. Within the framework of the ventricular pressure-volume diagram, the slope of the ventricular end-systolic pressure-volume relationship (expressed as ventricular end-systolic elastance, Ees), has been shown to accurately reflect ventricular inotropic state, and to be insensitive to loading conditions. It has not, however, been widely used at the bedside. Our goal was to evaluate the clinical utility of Ees and the ventricular pressure-volume diagram as bedside methods of hemodynamic assessment. We performed a prospective study of 123 hemodynamic interventions in 100 trauma patients during shock resuscitation in which contractility (Ees), preload (left ventricular end-diastolic volume index), and afterload (effective arterial elastance) were calculated before and after addition of inotropes, fluid bolus, and afterload reduction. Mean values of each variable were compared before and after each type intervention using the paired t test. The ventricular pressure-volume diagram was used to predict changes in the studied variables, and the experimental results were compared with predicted changes. Ees (mmHg/mL/m2) increased significantly with inotropes (4.7 +/- 3.2 to 10 +/- 8.7, p < .0001), but was not affected by clinically significant fluid administration (7.0 +/- 4.7 to 8.3 +/- 8.0, p = .10) or afterload reduction (9.6 +/- 5.2 to 9.2 +/- 4.7, p = .72). Left ventricular end-diastolic volume index (mL/m2) improved with fluid administration (54 +/- 8.9 to 62 +/- 9.8, p < .0001) and effective arterial elastance (mmHg/mL/m2) decreased with afterload reduction (3.3 +/- .9 to 2.6 +/- .7, p < .0001). We conclude that Ees is a load-independent measure of contractility, which is measurable at the bedside. The pressure-volume diagram is a useful method of monitoring hemodynamic changes associated with interventions during shock resuscitation.

New videodensitometric method for measuring renal artery blood flow at routine arteriography: validation in the canine model.

A contrast medium was injected in the aortic arch and selectively in a renal artery to estimate the renal blood flow as a percentage of the cardiac output by the videodensitometric (VD) method. Twenty-six paired VD measurements in four mongrel dogs were obtained and the results compared to electromagnetic (EM) flow readings from the aortic arch and a renal artery. The relative renal blood flow estimated by the VD method averaged 9.1% and correlated with the EM flow average of 9.6% with r = 0.96. Previous in vitro investigations of relative flow in a model have now been validated in vivo. These results suggest that videodensitometry could be a clinical tool for measuring renal blood flow in conjunction with routine arteriography.

Assessment of peripheral blood flow in man by video dilution technique: a preliminary report.

Video dilution technique is now available for clinical use in evaluating patients with peripheral vascular disease. The measurements can easily be performed in any modern angiographic suite. The only additional equipment required is a videodensitometer, video tape recorder, and a strip chart recorded. The new technique has been developed and tested in a hydrodynamic model and compared to volumetric flows. Further, the video dilution technique has been compared to electromagnetic flow readings using a canine model to measure the cerebral, renal, splanchnic, and extremity circulation and has proven to be extremely accurate (n = 389; r = 0.99). By applying the technique to patients with peripheral vascular disease, it is possible to evaluate the hemodynamic significance of stenotic lesions and arteriovenous shunts. Other uses of video dilution technique include evaluating the effects of vasoactive drugs and the adequacy of transluminal angioplasty.

Comparison of peripheral and central infusions of 7.5% NaCl/6% dextran 70.

Although it had been known for several years that central venous injections of hypertonic salt solutions with added dextran could effectively resuscitate animals from hemorrhagic shock, it was not known whether peripheral injections could result in the same beneficial effects. Chronically instrumented, unrestrained, and unanesthetized sheep were subjected to a moderate degree of hemorrhagic shock and then resuscitated with a 2-minute infusion of 7.5% NaCl/6% dextran 70 in a volume of 5 ml/kg body weight. Infusions were made into the cephalic vein, the femoral artery, or, centrally, the superior vena cava. All three routes of injection promptly reestablished arterial pressure and cardiac output. All gave equivalently good restoration of plasma volume. None of the injections damaged the vessels, as determined either by gross inspection or by histologic examination. Thus the solution was safe and effective when given peripherally. It might be useful in the field resuscitation of hypovolemic patients.

Effect of prostaglandin blockers on ascites fluid in pancreatitis.

UNLABELLED: Prostacyclin (PGI2), a potent vasodilator with complex effects on the mesenteric circulation, has been found to be elevated in the hemorrhagic ascitic fluid of pigs with hemorrhagic pancreatitis. This investigation was designed to determine if blockage of PGI2 significantly reduces the volume and/or toxicity of hemorrhagic ascitic fluid associated with hemorrhagic pancreatitis in pigs. Fifteen pigs were studied: five received corticosteroids, five received ibuprofen, and five were untreated. The relative toxicity of the hemorrhagic ascitic fluid was assessed by intraperitoneal injections of the fluid from pigs into mice. RESULTS: (1) hemorrhagic pancreatitis was associated with high levels of PGI2 in blood 15 times and in hemorrhagic ascitic fluid 25 times that of baseline; (2) steroids and ibuprofen blocked PGI2 production (p less than 0.05); (3) neither steroids nor ibuprofen, even when administered as pretreatment, decreased ascites formation; and (4) the mortality rate in mice was significantly reduced (p less than 0.05) in the ibuprofen-treated group as compared with the untreated and steroid-treated groups. CONCLUSION: PGI2 does not play a significant role in the volume of ascites formation. There was an absence of toxicity in the hemorrhagic ascitic fluid of the ibuprofen-treated group.

Small-volume resuscitation with hypertonic saline dextran solution.

Small-volume hypertonic resuscitation has been proposed as an effective means for restoration of cardiovascular function after hemorrhage at the scene of an accident. We evaluated the cardiovascular, metabolic, and neurohumoral response of resuscitation after hemorrhage using 200 ml of 2400 mosm sodium chloride, 6% dextran 70. Unanesthetized adult sheep were bled to maintain mean arterial pressure at 50 mm Hg for 3 hours, shed blood volume = 42 +/- 7 ml/kg. The sheep were then treated with a single bolus infusion of hypertonic saline dextran (n = 7) or normal saline solution (control group, n = 7) and then observed for a 30-minute period of simulated patient transport during which no additional fluid was given. Hypertonic saline dextran caused rapid restoration of blood pressure and cardiac output within 2 minutes of infusion. Cardiac output remained at or above baseline level, while both O2 consumption and urine output increased to above baseline level during the 30 minutes of simulated patient transport. By comparison 200 ml of normal saline solution caused only a small increase in blood pressure and no improvement in cardiac output or oxygen consumption. After this 30-minute period, both groups were given lactated Ringer's solution as needed to return and maintain cardiac output at its baseline value. The volume of lactated Ringer's solution required to maintain cardiac output was less in the hypertonic group, 371 +/- 168 ml, only one sixth that of the control group, 2200 +/- 814 ml. In summary after 3 hours of hypovolemia, a small volume of hypertonic saline dextran, about 4 ml/kg, fully restored cardiovascular and metabolic function for at least 30 minutes and significantly lowered the total volume requirements of resuscitation.

The mangled extremity. When to amputate?

To determine indications for immediate or delayed amputation of the mangled lower extremity, we reviewed the cases of 80 patients. Vascular, neurologic, bone, and soft-tissue status were reviewed, as were postoperative complications, requirements for mechanical ventilation, fluid balance, delayed amputation, and survival. Although neurologic, bone, and soft-tissue status did influence decisions regarding immediate amputation, they had little to do with delayed loss of limb or life. The circulation, as determined by the presence or absence of a palpable or Doppler-detected pulse, however, was critical. Of six patients in whom salvage was attempted and in whom fluid balances of greater than 3 L were detected in the first 24 hours post-operatively, five eventually required amputation. Salvage should usually be attempted if a distal pulse is present. If no distal pulse is present, the decision for immediate amputation should be based on functional prognosis. In cases in which salvage is attempted, amputation should be performed at 24 hours if the patient's condition, including a markedly positive fluid balance, indicates systemic compromise. In the absence of a distal pulse on presentation, the eventual amputation rate is high.

New concepts in the use of axillofemoral bypass grafts.

Over a four-year period, 52 patients underwent axillofemoral bypass operations. Indications for operation were divided into three groups: those that were performed emergently (aortoenteric fistula, graft infection, and leaking aortic aneurysm), those performed electively for aneurysm, and those for ischemia. Operative procedures were categorized as follows: axillofemoral bypass alone, axillofemorofemoral bypass with the proximal femorofemoral anastomosis being graft to graft, or axillofemorofemoral bypass with the femorofemoral anastomosis to either a transected proximal common femoral artery or superficial femoral artery distal to the axillofemoral anastomosis. Thirty-three percent of the unilateral axillofemoral grafts failed, while only 14% of the axillobifemoral grafts failed. There was a further difference between the two methods of femorofemoral grafting with 22% failure in the former group but no failures in the latter.

Appendicitis. A critical review of diagnosis and treatment in 1,000 cases.

One thousand cases of appendicitis seen from 1963 to 1973 were reviewed. The overall negative appendectomy rate was 20%, but in women between ages 20 and 40 it exceeded 40%. Two thirds of the negative appendectomies were due to nonsurgical lesions. Mesenteric adenitis, gastroenteritis, and abdominal pain of unknown cause accounted for one third of the errors in females and two thirds in males. These diseases were best distinguished from appendicitis on the basis of temperature and white blood cell count. The remainder of the errors in females were due to pelvic inflammatory disease or other gynecologic diagnosis and were best distinguished from appendicitis on the basis of history and physical findings. The rate of perforation was 21% overall. The incidence of wound infection was 8.5%. Use of systemic antibiotics did not affect the wound infection rate.

Analysis of potential risks associated with 7.5% sodium chloride resuscitation of traumatic shock.

We evaluated the potential side effects of rapidly infusing 250 mL of either 7.5% sodium chloride or 7.5% sodium chloride per 6% dextran 70, using lactated Ringer's as the control, to 106 critically injured patients in two prospective double-blinded emergency department trials. Eight patients had a significant hyperchloremic acidemia in association with infusion of the hypertonic solutions, but all eight were moribund before infusion and many factors other than hyperchloremia could have contributed to their acidemia. Other blood chemistry changes that might have been associated with the hypertonic solutions, such as hyperosmolality or hypernatremia, were made insignificant by other factors, such as high blood alcohol levels or concomitant administration of sodium bicarbonate. There were no cases of central pontine myelinolysis; bleeding was not potentiated. There was no difficulty with crossmatching of blood. No anaphylactoid reactions occurred. In a setting of limited volume resuscitation, the solutions are likely to have a favorable risk-to-benefit ratio.

7.5% sodium chloride/dextran for resuscitation of trauma patients undergoing helicopter transport.

To evaluate the use of hypertonic saline/dextran solutions in the prehospital resuscitation of severely injured patients, we administered 250 mL of either 7.5% sodium chloride/dextran 70 (HSD) (n = 83) or lactated Ringer's solution (n = 83), followed by conventional isotonic fluids, to 166 trauma patients with systolic blood pressures less than or equal to 100 mm Hg, in a prospective, randomized, double-blinded clinical trial. Patients in the sodium chloride/dextran 70 group required less fluid before hospitalization and arrived in the emergency department with higher systolic blood pressures than patients in the lactated Ringer's solution group. The rate of survival to hospital discharge for the entire cohort was 64% for patients in the sodium chloride/dextran 70 group vs 59% for patients in the lactated Ringer's solution group. The rate of survival to hospital discharge for the patients with severe head injuries was 32% for the sodium chloride/dextran 70 group vs 16% for the lactated Ringer's solution group. Actuarial survival for patients with severe head injuries in the sodium chloride/dextran 70 group compared with patients with severe head injuries in the lactated Ringer's solution group did not quite reach statistical significance. There were no adverse side effects associated with sodium chloride/dextran 70 administration. Administration of small volumes of sodium chloride/dextran 70 before hospitalization increased the blood pressure of severely injured patients more effectively than did lactated Ringer's solution and showed tendencies toward improving survival in the patients with severe head injuries.

Early fluid requirements in trauma patients. A predictor of pulmonary failure and mortality.

The fluid required for initial resuscitation of trauma patients should reflect, at least in part, the severity of the original injuries and shock. We examined the hypothesis that the initial fluid requirements might also predict development of subsequent pulmonary failure and death. Fluid balances were calculated for the first 24 hours in the intensive care unit for 100 high-risk trauma patients. The mean (+/- 1 SD) fluid balance for 63 patients who developed pulmonary failure was 4.6 +/- 5.5 L; the mean balances for the 37 patients who did not develop pulmonary failure were 1.0 +/- 3.1 L. The balances in 23 patients who died and in 77 who survived were 6.8 +/- 5.4 and 2.2 +/- 4.5 L, respectively. A cutoff value of 3 L determined prospectively before beginning the study predicted pulmonary failure with a sensitivity of 52% and a specificity of 89%. For mortality, the 3-L cutoff point gave a sensitivity of 74% and a specificity of 74%. The predictive value of the fluid balance was independent of other prognostic indicators, such as revised trauma scores, injury Severity Scores, and modified APACHE II scores. This simple measurement should help in allocating intensive care unit resources, as patients in positive fluid balance are likely to require Swan-Ganz catheterization and are likely to require long-term mechanical ventilation. The fluid balance should also be useful in stratifying patients for entry into clinical trials.

Video dilution technique. An accurate measure of blood flow during routine arteriography.

The video dilution technique for measuring blood flow consists of electronically and mathematically processing video-taped selective arteriograms to measure the flow in selectively catheterized arteries and to express this flow as a fraction of the flow in any reference artery. Flows were measured by video dilution and an electromagnetic flowmeter in ten dogs; the correlations were excellent. Video dilution flows were also measured in 105 patients. The technique is accurate, simple, and adds no risk to routine selective arteriography.

A multicenter trial for resuscitation of injured patients with 7.5% sodium chloride. The effect of added dextran 70. The Multicenter Group for the Study of Hypertonic Saline in Trauma Patients.

OBJECTIVE: To evaluate the use of 250 mL of a 7.5% sodium chloride solution, both with and without added dextran 70, for the prehospital resuscitation of hypotensive trauma patients. DESIGN: Double-blind randomized trial. SETTING: Six trauma systems served by helicopter transport. PATIENTS: Injured patients with systolic blood pressures less than 90 mm Hg at any time in the field or during helicopter transport. INTERVENTIONS: Infusion of study solution, in the field or during transport, followed by conventional isotonic solutions as needed. Solutions studied in four cohorts were as follows: (1) lactated Ringer's; (2) 7.5% sodium chloride (hypertonic saline); (3) 7.5% sodium chloride combined with 6% dextran 70; and (4) 7.5% sodium chloride combined with 12% dextran 70. MAIN OUTCOME MEASURES: Blood pressure response; survival to time of hospital discharge among the treatment groups; and survival compared with that predicted by norms from the Major Trauma Outcome Study (MTOS). RESULTS: The mean (+/- SD) change in systolic blood pressure on arrival in the emergency department was significantly higher in the hypertonic saline solution group than that in the lactated Ringer's solution group (34 +/- 46 vs 11 +/- 49 mm Hg, P < .03). Overall survival in the four treatment groups was 49%, 60%, 56%, and 45% (not statistically significant). Survival in the hypertonic saline solution group, however, was significantly higher than that predicted by the MTOS norms (60% vs 48%, P < .001). Survival to hospital discharge in patients with baseline Glasgow Coma Scale scores of 8 or less was correlated with treatment group (P < .05 by logistic regression and P < .01 by Cox proportional-hazards analysis; with survival in the hypertonic saline solution group [34%] vs lactated Ringer's solution group [12%]). CONCLUSIONS: Prehospital infusion of 250 mL of 7.5% sodium chloride is associated with an increase in blood pressure and an increase in survival to hospital discharge compared with survival predicted by the MTOS norms. Patients with low baseline Glasgow Coma Scale scores seem to benefit the most from 7.5% sodium chloride resuscitation. Hypertonic saline solution without added dextran 70 is as effective as the more expensive solutions that contain dextran 70.

Simple ligation vs stump inversion in appendectomy.

The records of 886 patients who had appendectomy performed by the same surgeons within a five-year period were used to contrast appendiceal stump inversion vs simple ligation. Our analysis contrasted inversion vs simple ligation techniques as related to postoperative complications, hospital stay, and pathologic diagnosis. Adhesions requiring repeated operation to relieve bowel obstruction occurred in five of 87 patients with acute gangrenous appendicitis treated by inversion. Of 106 patients with acute gangrenous appendicitis treated with simple ligation, postoperative obstruction developed in none. No other statistically significant differences existed between the two techniques. These data suggest that simple ligation is at least as good as and probably better than inversion of the appendiceal stump.

Measurement of 6-keto-PGF1 alpha and thromboxane B2 levels in critically ill surgical patients.

Systemic arterial and mixed venous plasma concentrations of 6-keto-PGF1 alpha and TxB2 were measured by radioimmunoassay in 63 critically ill patients with major trauma (n = 20) or sepsis (n = 43). Patients undergoing elective catheterization procedures served as controls (n = 10). Arterial and mixed venous 6-keto-PGF1 alpha and TxB2 levels were significantly elevated in patients with recent major trauma or active sepsis. The 6-keto-PGF1 alpha levels were found to be significantly elevated in the non-survivors and in patients with hepatic failure. The presence of severe pulmonary failure was not associated with increased levels of either 6-keto-PGF1 alpha or TxB2. Comparison of arterial and mixed plasma samples did not demonstrate increased pulmonary release of either compound. Increased eicosanoid production may account, in part, for the local vascular and humoral responses to tissue injury or infection.

Evaluation of prostaglandin E1 for prevention of respiratory failure in high risk trauma patients: a prospective clinical trial and correlation with plasma suppressive factors for neutrophil activation.

A group of 48 critically injured patients were entered into a prospective, double-blind, placebo-controlled trial to evaluate the efficacy of early infusion of PGE1 for reducing the incidence of severe respiratory failure and mortality. Secondary assessments examined the effects of the PGE1 infusion on plasma mediated suppression of PMN superoxide production and loss of PMN granule enzyme content. The incidence of severe respiratory failure was lower in the PGE1 group--13% versus 32%, but this did not reach significance. The overall morality was equivalent between the two groups--26% (PGE1) versus 28% (placebo). The suppressive activity of the patient plasma was assayed by measurement of normal PMN superoxide production relative to normal control plasma (ratio P:C). The baseline ratio P:C was 62 +/- 5% in the PGE1 group versus 60 +/- 5% in the placebo group. The day 1 plasma samples showed significant reversal of plasma suppressive activity in the PGE1 group--ratio P:C 88 +/- 5% versus 67 +/- 5% in the placebo group (P less than 0.02). In patients who received the full 7 days of infusion, the plasma suppressive activity remained significantly diminished in the PGE1 group--ratio P:C 77 +/- 4% versus 61 +/- 5% (P less than 0.04). The baseline lysozyme content of patient PMN's relative to that of normal control PMNs (ratio P:C) was 119 +/- 14% in the PGE1 group. A significant loss of lysozyme content was observed in the PGE1 group on day 1 of the infusion--ratio P:C 79 +/- 8% (P less than 0.03), and was associated with a reduction in the plasma suppressive activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Physician recognition of hypercholesterolemia in patients undergoing peripheral and carotid artery revascularization.

Numerous studies have shown that patients with peripheral and carotid atherosclerosis have a high prevalence of hyperlipidemia, and clinical trials using either angiography or ultrasonography have now demonstrated regression of both femoral and carotid arterial plaque during lipid-lowering therapy. However, whether patients with peripheral and carotid atherosclerosis receive adequate attention to lipid risk factors has not been studied. To evaluate physician recognition and management of hypercholesterolemia in these two patient populations, we reviewed the charts of 80 consecutive patients undergoing revascularization for symptomatic peripheral and carotid occlusive disease at a university medical center between 1990 and 1993. Physician practices were assessed for each patient by noting whether hypercholesterolemia was (1) screened for during the hospitalization and, if present, (2) documented as a problem, (3) managed in-hospital, or (4) given appropriate intervention at discharge. While 73% of patients received some type of lipid case-finding perioperatively, less than one quarter of these were assessed for hyperlipidemia by the physician during the initial history. Moreover, of the 66% of screened patients found to be hypercholesterolemic, only 16% had documentation of the problem, only 24% received in-hospital management, and only 13% received intervention at discharge. These findings suggest that patients with documented peripheral and carotid atherosclerotic vascular disease probably receive inadequate attention to lipid risk factors and indicate the need for greater awareness and management of lipid disorders in these two patient populations by all involved physicians.

A prospective, randomized trial limiting perioperative red blood cell transfusions in vascular patients.

BACKGROUND: Patients undergoing major arterial reconstruction have traditionally been transfused with red blood cells to keep hemoglobin concentrations above 10 g/dL in order to prevent anemia-induced myocardial ischemia. There are no data to support this practice. The hypothesis that vascular patients will tolerate a hemoglobin concentration of 9 g/dL was examined. METHODS: Ninety-nine patients undergoing elective aortic and infrainguinal arterial reconstructions were prospectively randomized preoperatively to receive transfusions to maintain a hemoglobin level of either 10 g/dL or 9 g/dL. RESULTS: Despite significantly different postoperative hemoglobin levels of 11.0 +/- 1.2 versus 9.8 +/- 1.3 g/dL (P <0.0001), there were no differences in mortality or cardiac morbidity rates or length of hospital stay. There were no differences in hemodynamic parameters. Oxygen delivery was lower in the group with lower hemoglobin levels, but there was no difference in O2 consumption between the groups. CONCLUSIONS: A lower hemoglobin concentration was tolerated without adverse clinical outcome. Patients did not compensate for anemia by increased myocardial work, but by increasing O2 extraction in the peripheral tissues.

Unusual problems of abdominal aortic aneurysms.

Complications other than rupture occurred in 12 per cent of 254 patients operated on for an infrarenal abdominal aortic aneurysm. The unusual problems encountered included aortocaval fistula, inflammatory aneurysm, aortoenteric fistula, aortic thrombosis, peripheral embolization, and retropsoas rupture. The clinical manifestations and management of these lesions are discussed.