Measurement of cardiac output by transpulmonary arterial thermodilution using a long radial artery catheter. A comparison with intermittent pulmonary artery thermodilution.

Cardiac output can be measured accurately by transpulmonary arterial thermodilution using the PiCCO (Pulsion Medical Systems, Munich, Germany) system with a femoral artery catheter. We have investigated the accuracy of a new 50 cm 4 French gauge radial artery catheter and the ability to use the system with a shorter radial catheter. We studied 18 patients who had undergone coronary artery surgery and made three simultaneous measurements of cardiac output by arterial thermodilution and with a pulmonary artery catheter. The radial catheter was withdrawn in 5 cm increments and the measurements were repeated. We found close agreement between arterial thermodilution and pulmonary artery thermodilution with a mean (SD) bias of 0.38 (0.77) l x min(-1). Arterial thermodilution became unreliable once the catheter had been withdrawn by more than 5 cm. We conclude that cardiac output measurement with arterial thermodilution with a radial catheter is interchangeable with that derived from a pulmonary artery catheter, and that a centrally sited arterial catheter is required for accurate determination of cardiac output by transpulmonary arterial thermodilution.

Research and development of an implantable, axial-flow left ventricular assist device: the Jarvik 2000 Heart.

Advances in technology and increased clinical need have led to the development of a new type of blood pump. The Jarvik 2000 Heart is an electrically powered, axial-flow left ventricular assist device that has been developed during the past 13 years. Unlike first-generation left ventricular assist devices, which were developed in the 1970s and were designed to totally capture the cardiac output, the Jarvik 2000 is designed to normalize the cardiac output by augmenting the function of the chronically failed heart for extended periods. Design iterations have been tested in 67 animals, and clinical trials have recently begun. Three patients have received the Jarvik 2000 as a bridge to transplantation, and 1 patient is being supported permanently outside the hospital. All 4 patients have improved from New York Heart Association functional class IV to class I, and 2 of them have been discharged from the hospital after heart transplantation. The experimental and clinical results indicate that the Jarvik 2000 can provide physiologic support with minimal complications and is reliable, biocompatible, and easy to implant.

First permanent implant of the Jarvik 2000 Heart.

BACKGROUND: Heart failure is a major public-health concern. Quality and duration of life on maximum medical therapy are poor. The availability of donor hearts is severely limited, therefore an alternative approach is necessary. We have explored the use of a new type of left-ventricular assist device intended as a long-term solution to end-stage heart failure. METHODS: As part of a prospective clinical trial, we implanted the first permanent Jarvik 2000 Heart--an intraventricular device with an innovative power delivery system--into a 61-year-old man (New York Heart Association functional class IV) with dilated cardiomyopathy. We assessed the effect of this left-ventricular assist device on both native heart function and the symptoms and systemic characteristics of heart failure. FINDINGS: The Jarvik 2000 Heart sustained the patient's circulation, and was practical and user-friendly. After 6 weeks, exercise tolerance, myocardial function, and end-organ function improved. Symptoms of heart failure have resolved, and continuous decreased pulse-pressure perfusion has had no adverse effects in the short term. There has been no significant haemolysis and no device-related complications. The skull-mounted pedestal is unobtrusive and has healed well. CONCLUSIONS: The initial success of this procedure raises the possibility of a new treatment for end-stage heart failure. In the longer term, its role will be determined by mechanical reliability.

Effect of omitting regular ACE inhibitor medication before cardiac surgery on haemodynamic variables and vasoactive drug requirements.

Adverse events during coronary artery bypass graft (CABG) surgery have been described in patients receiving angiotensin converting enzyme (ACE) inhibitors, including hypotension on induction of anaesthesia and an increase in vasoconstrictor requirements after cardiopulmonary bypass (CPB). Omitting regular ACE inhibitor medication before surgery may improve cardiovascular stability during anaesthesia. We evaluated prospectively the effect of omitting regular ACE inhibitor medication before CABG surgery on haemodynamic variables and use of vasoactive drugs. We studied 40 patients with good left ventricular function, allocated randomly to omit or continue ACE inhibitor medication before surgery. Arterial pressure, cardiac output, systemic vascular resistance and use of vasoactive drugs were recorded during anaesthesia and in the early postoperative period. Patients who omitted their ACE inhibitors had greater mean arterial pressure during the study and required less vasopressors during CPB. However, these patients required more vasodilators to control hypertension after CPB and in the early postoperative period. There was no difference in hypotension on induction of anaesthesia or in the use of vasoconstrictors after CPB. We conclude that omitting ACE inhibitors before surgery did not have sufficient advantage to be recommended routinely.

The cuffed oropharyngeal airway as an aid to fibreoptic intubation.

The cuffed oropharyngeal airway is a new disposable airway based on the Guedel oral airway. It has an asymmetrical cuff which provides a seal as well as lifting the base of the tongue forwards, and a 15-mm connector allowing attachment to an anaesthetic breathing system. The device does not extend beyond the vallecula, so that the laryngeal inlet can be visualised with a fibreoptic laryngoscope passed between the cuff of the device and the pharyngeal wall. The advantage is that ventilation is maintained throughout the intubating sequence. We describe its use in a patient with oropharyngeal carcinoma.

Continuous measurement of arterial blood gas status during total hip replacement: a prospective study.

The arterial blood gas chemistry was measured continuously in ten patients during primary cemented total hip replacement in order to define more precisely the patterns of changes in blood gases during various stages of the operation. All ten patients demonstrated significant drops in PaO2 after femoral cement implantation and nine of the ten after acetabular cement implantation. The mean drop in PaO2 following acetabular cement expressed as mean +/- SD was 18 +/- 8 mmHg (16 +/- 6%) (P < 0.05) and femoral cement application was 25 +/- 11 mmHg (23 +/- 9%) (P < 0.05). For changes in PaO2 there were corresponding drops in SpO2 in all patients with the femoral cement and in eight patients with the acetabular cement. The mean drop in SpO2 following the application of acetabular and femoral cements respectively were 1.7 +/- 1.5% and 3 +/- 2.45%. No changes in blood PaO2 were observed during dislocation of the hip joint or reaming of acetabulum and femur. In vitro studies revealed no effect of the liquid monomer or the cured cement on the performance of the Clark electrode of the sensor. We suggest that significant drops in PaO2 occur with both acetabular and femoral cement implantation and that the derangements in blood PaO2 last longer than detected by pulse oximetry following cement implantation.