Hemodynamic waveform analysis.

The pulmonary artery catheter provides the opportunity to acquire indirectly important diagnostic and therapeutic information about the function of the two pumping chambers of the heart--the right and left ventricles--during the two phases of the cardiac cycle--systole and diastole. Appropriate use of hemodynamic data acquired via the pulmonary artery catheter requires the accurate measurement, analysis, and interpretation of hemodynamic pressure waveforms.

Randomized trial of diaspirin cross-linked hemoglobin solution as an alternative to blood transfusion after cardiac surgery. The DCLHb Cardiac Surgery Trial Collaborative Group.

BACKGROUND: Risks associated with transfusion of allogeneic blood have prompted development of methods to avoid or reduce blood transfusions. New oxygen-carrying compounds such as diaspirin cross-linked hemoglobin (DCLHb) could enable more patients to avoid allogeneic blood transfusion. METHODS: The efficacy, safety, hemodynamic effects, and plasma persistence of DCLHb were investigated in a randomized, active-control, single-blind, multicenter study in post-cardiac bypass surgery patients. Of 1,956 screened patients, 209 were determined to require a blood transfusion and met the inclusion criteria during the 24-h post-cardiac bypass period. These patients were randomized to receive up to three 250-ml infusions of DCLHb (n = 104) or three units of packed erythrocytes (pRBCs; n = 105). Further transfusions of pRBCs or whole blood were permitted, if indicated. Primary efficacy end points were the avoidance of blood transfusion through hospital discharge or 7 days postsurgery, whichever came first, and a reduction in the number of units of pRBCs transfused during this same time period. Various laboratory, physiologic, and hemodynamic parameters were monitored to define the safety and pharmacologic effect of DCLHb in this patient population. RESULTS: During the period from the end of cardiopulmonary bypass surgery through postoperative day 7 or hospital discharge, 20 of 104 (19%) DCLHb recipients did not receive a transfusion of pRBCs compared with 100% of control patients (P < 0.05). The overall number of pRBCs administered during the 7-day postoperative period was not significantly different. Mortality was similar between the DCLHb (6 of 104 patients) and the control (8 of 105 patients) groups. Hypertension, jaundice/hyperbilirubinemia, increased serum glutamic oxalo-acetic transaminase, abnormal urine, and hematuria were reported more frequently in the DCLHb group, and there was one case of renal failure in each group. The hemodynamic effects of DCLHb included a consistent and slightly greater increase in systemic and pulmonary vascular resistance with associated increases in systemic and pulmonary arterial pressures compared with pRBC. Cardiac output values decreased more in the DCLHb group patients after the first administration than the control group patients. At 24 h postinfusion, the plasma hemoglobin level was less than one half the maximal level for any amount of DCLHb infused. CONCLUSIONS: Administration of DCLHb allowed a significant number (19%) of cardiac surgery patients to avoid exposure to erythrocytes postoperatively.

A safety assessment of diaspirin cross-linked hemoglobin (DCLHb) in the treatment of hemorrhagic, hypovolemic shock.

OBJECTIVE: To determine the safety and possible efficacy of diaspirin cross-linked hemoglobin (DCLHb) in the treatment of patients in Class II-IV hemorrhagic, hypovolemic shock. DESIGN: Multicenter, randomized, normal saline-controlled, dose-escalation study. SETTING: Eleven hospitals in the U.S. and Belgium. SUBJECTS: One hundred and thirty-nine (139) hospitalized patients with Class II-IV hemorrhagic, hypovolemic shock within the previous 4 hours who still were requiring therapy for shock. INTERVENTIONS: Beginning with the lowest dose, patients were randomized to receive 50, 100, or 200 mL of either 10% DCLHb or normal saline infused intravenously over 15 minutes. Following infusion of either treatment, further fluid resuscitation could be given, as necessary, to maintain perfusion. Vital signs, laboratory assessments, blood and fluid administration, complications, and adverse events were recorded at various times from the end of infusion through 72 hours after infusion. RESULTS: A total of 29 (13 DCLHb- and 16 saline-treated) patients died during the study period. Adverse events were experienced by 61% of patients in the DCLHb group and 53% of patients in the saline group; serious adverse events occurred in 28% of DCLHb-treated patients and 30% of saline-treated patients. The incidence of prospectively defined, clinical complications, including renal insufficiency and renal failure, was similar between the treatment groups except for the occurrence of dysrhythmias/conduction disorders, which occurred significantly more frequently in the saline-treated patients than the DCLHb-treated patients (p = 0.041). At the highest dose level (200 mL), statistically significant between-group differences were observed with greater increases in serum amylase, LDH, the isoenzymes LD1,2,4 and 5, and CK-MB in the DCLHb group compared to the control group; none were of clinical significance. The volume of blood administered did not differ between the groups. Overall 24- and 72-hour survival rates were similar between treatment groups, although the hospital discharge rate was slightly higher in the DCLHb-treated patients (80%) compared with the saline-treated patients (74%). CONCLUSION: Administration of 50 to 200 mL of DCLHb to patients in hemorrhagic, hypovolemic shock was not associated with evidence of end organ toxicity or significant adverse events. Further studies involving larger doses and, perhaps, earlier administration of DCLHb are warranted.

Initial evaluation of diaspirin cross-linked hemoglobin (DCLHb) as a vasopressor in critically ill patients.

OBJECTIVE: To evaluate the hemodynamic effects and any toxicologic effects of diaspirin cross-linked hemoglobin (DCLHb) in critically ill patients. DESIGN: A prospective, observational study. SETTING: A seven-bed intensive care unit (ICU) in a University teaching hospital. PATIENTS: Fourteen critically ill patients requiring vasopressor therapy to maintain adequate mean arterial pressure (MAP). All patients had secondary organ dysfunction. INTERVENTIONS: Administration of 100 mL boluses of 10% diaspirin cross-linked hemoglobin, up to a maximum of 500 mL, given over 15 mins and separated by 60 to 90 mins. MEASUREMENTS AND MAIN RESULTS: Hemodynamic parameters, norepinephrine and inotropic requirements, arterial and mixed venous blood gases, urine output, and biochemical and hematologic analyses were measured before diaspirin cross-linked hemoglobin administration and at multiple time points up to 72 hrs. MAP was maintained at approximately preinfusion values and the reduction in norepinephrine requirements was used as the main end point to assess the efficacy of diaspirin cross-linked hemoglobin as a vasopressor. Diaspirin cross-linked hemoglobin demonstrated a marked vasopressor action, allowing norepinephrine requirements to be reduced from 0.29 +/- 0.15 (SD) microgram/kg/min to 0.15 +/- 0.14 and 0.07 +/- 0.10 microgram/kg/min after the first (at 1.5 hrs, p < .001) and last (at 7.5 hrs, p < .0001) boluses, respectively. These reductions in norepinephrine requirements were maintained at 24, 48, and 72 hrs (p < .01 at all time points). These hemodynamic changes began within 5 mins of starting the diaspirin cross-linked hemoglobin infusion. MAP, heart rate, central venous pressure, pulmonary artery occlusion pressure, mean pulmonary arterial pressure (MPAP), systemic vascular resistance index, and urine output did not demonstrate any significant changes from preinfusion values. Pulmonary vascular resistance index increased at 7.5 hrs despite nonsignificant increases in MPAP. Cardiac index and oxygen delivery index decreased significantly at 7.5 hrs and 24 hrs. Total plasma bilirubin increased significantly from baseline at 24 and 48 hrs, before returning to baseline values within 5 days. Platelet count was significantly reduced at 6 and 24 hrs. No other biochemical or hematologic analyses were altered significantly post diaspirin cross-linked hemoglobin. CONCLUSIONS: This preliminary study demonstrated that diaspirin cross-linked hemoglobin is a potent vasopressor agent in critically ill patients with septicemic shock or systemic inflammatory response syndrome. This vasopressor characteristic of diaspirin cross-linked hemoglobin may have future clinical applications.

Phase I study of the safety and pharmacologic effects of diaspirin cross-linked hemoglobin solution.

OBJECTIVE: To evaluate the safety, pharmacokinetics, and pharmacodynamics of diaspirin cross-linked hemoglobin solution (DCLHb) in normal, healthy volunteers. DESIGN: Randomized, double-blind, controlled, crossover study. SETTING: Phase I research facility of a contract research organization. PATIENTS: Twenty-four healthy adult volunteers. INTERVENTIONS: Diaspirin cross-linked hemoglobin solution (25, 50, or 100 mg/kg) or equal volume of lactated Ringer's solution was infused on day 1; the alternate solution was infused 6 days later. Laboratory analyses, electrocardiograms, and Holter and telemetry monitoring were performed to assess organ function, pharmacokinetics, and potential toxicity. Vital signs, pulse oximetry, laser Doppler flowmetry, and toe temperature were measured to evaluate diaspirin cross-linked hemoglobin solution's pharmacodynamic effects. MEASUREMENTS AND MAIN RESULTS: There were no serious adverse events associated with diaspirin cross-linked hemoglobin solution infusion. Abdominal pain occurred in three subjects after control infusion and in six subjects after diaspirin cross-linked hemoglobin solution infusion; no treatment was required. A dose-related increase in lactic dehydrogenase (LDH)-5 isoenzyme concentrations was observed in 12 subjects after diaspirin cross-linked hemoglobin solution infusion. There were no associated increases in the circulating concentrations of total LDH, aspartate aminotransferase, alanine aminotransferase, or alkaline phosphatase. Total serum creatine kinase concentrations increased significantly after infusion of 100 mg/kg of diaspirin cross-linked hemoglobin solution; the isoenzyme creatine kinase-myocardial band (CK-MB) was not increased, nor were there any abnormal electrocardiogram findings. There were no differences in laser Doppler, pulse oximetry, or toe temperature measurements during or after either infusion. The half-life of diaspirin cross-linked hemoglobin solution was 2.5 hrs for the 25- and 50-mg/kg doses and 3.3 hrs for the 100-mg/kg dose. A dose-related increase in blood pressure occurred with diaspirin cross-linked hemoglobin solution. CONCLUSIONS: Diaspirin cross-linked hemoglobin solution doses of 25, 50, and 100 mg/kg are well tolerated, without evidence of organ dysfunction or toxicity. Diaspirin cross-linked hemoglobin solution's pressor effect is without evidence of decreased peripheral perfusion. Further investigations of its use in certain patient populations are warranted.

Assessment of critical care nurses' knowledge of the pulmonary artery catheter. The Pulmonary Artery Catheter Study Group.

OBJECTIVES: To assess the knowledge and understanding of the use of the pulmonary artery catheter and interpretation of data derived from it in a group of nurses attending the American Association of Critical Care Nurses' National Teaching Institute conference. DESIGN: A 37-question multiple choice examination that tested knowledge regarding the use of the pulmonary artery catheter was administered to a group of nurses, attending a national conference, who preregistered for a hemodynamics workshop. SETTING: American Association of Critical Care Nurses' National Teaching Institute Conference, New Orleans, LA, May 1992. MEASUREMENTS AND MAIN RESULTS: Two-hundred sixteen nurses completed the questionnaire. The mean test score was 16.5 +/- 5.7 (SD) (48.5%). Test scores were significantly associated with years of experience in critical care, critical care registered nurse certification, responsibility for repositioning and manipulating the catheter, frequency of use, and self-assessed adequacy of knowledge. CONCLUSIONS: A wide variation in the understanding of the use of the pulmonary artery catheter exists among nurses using this device in the care of seriously ill patients. The results indicate that current teaching practices regarding the pulmonary artery catheter need to be reevaluated and specific credentialing policies need to be considered.

Clinical management of patients receiving thrombolytic therapy.

Rapid delivery of thrombolytic therapy to suitable patients with acute myocardial infarction can limit myocardial damage and reduce the risk of death. This requires an emergency department team approach following a written protocol to initiate thrombolytic therapy within 45 minutes of the patient's arrival at the emergency department. Nurses and physicians caring for patients with acute myocardial infarction must be aware of inclusion and exclusion criteria, drug preparation, dosage and administration, recommended adjunctive therapies, and potential complications associated with pharmacologic thrombolysis. All patients with acute myocardial infarction should be carefully screened for their potential for receiving thrombolytic therapy with a favorable benefit/risk ratio.

Use of hemodynamics to differentiate pathophysiologic causes of cardiogenic shock.

Although extensive myocardial damage is the major cause of pump failure and cardiogenic shock, certain other mechanical defects associated with myocardial infarction may precipitate a severe shock state associated with a poor prognosis. Early recognition and differentiation of the underlying pathology is essential for prompt, appropriate treatment to correct the underlying causative disorder and change the course of the cascading factors that eventually lead to the patient's death. Frequently, this requires the direct measurement and assessment of hemodynamic perameters obtained from intravascular catheters.

Percutaneous balloon valvuloplasty in adult patients with valvular heart disease.

Percutaneous balloon valvuloplasty is a new, nonsurgical technique for treatment of acquired mitral or aortic valvular stenosis. The procedure is still investigational and performed following approved research protocols. Although technically more difficult and at times impossible to perform, percutaneous BV of the mitral valve has been shown to be both safe and effective for increasing the mitral valve orifice area and for relief of symptoms associated with severe rheumatic mitral stenosis. Because of the relative infancy of the procedure, long-term data are available for only 1 to 2 years following BV. Thus far, however results obtained with mitral BV are similar to those obtained using surgical commissurotomy. From a long-term perspective, results of aortic BV in the elderly population are less impressive. The procedure appears to be only palliative and is associated with high rates of restenosis occurring fairly soon after the procedure. However, in the very elderly patient who is a nonsurgical candidate, aortic BV can provide improvement in aortic valve orifice size and in relief of debilitating symptoms associated with severe aortic stenosis. As with surgical aortic valve replacement, aortic BV also provides improvement over the natural course of the disease. More data are needed to aid in better definition and selection of patients who are suitable candidates for this procedure.

Use of fiber-optic pressure transducer for intracranial pressure measurements: a preliminary report.

Invasive monitoring of intracranial pressure (ICP) is becoming the standard of care for management of acute neurologic and neurosurgical patients. As a result of improved fiber-optic technology, a new disposable 4 French fiber-optic transducer-tipped catheter (FTC) has been introduced for facilitating measurement of intracranial pressure. Placement of the FTC can be intraventricular, subarachnoid, subdural, or intraparenchymal. Sensitivity and linearity of each catheter are manufacturer calibrated and not adjustable. Zero or atmospheric balance is done only once before insertion. Because the transducer is the catheter tip, no leveling to an anatomic point is necessary. The system appears to eliminate some of the difficulties inherent in fluid-filled catheter monitoring. In clinical trials, the comparison of FTC with subdural and ventriculostomy waveforms and pressures showed essentially no difference. Pressure recordings tracked well except during transient periods of increased ICP, when FTC showed higher peak pressures. Use of the FTC requires education regarding placement and maintenance techniques. Although staff experience with the catheter can practically eliminate the problem, the FTC catheters need special handling because of potential for fiber breakage.