Cardiac output measured by lithium dilution and transpulmonary thermodilution in patients in a paediatric intensive care unit.

OBJECTIVE: To compare the results of cardiac output measurements obtained by lithium dilution and transpulmonary thermodilution in paediatric patients. DESIGN: A prospective study. SETTING: Paediatric intensive care unit in a university teaching hospital. PATIENTS: Twenty patients (age 5 days-9 years; weight 2.6-28.2 kg) were studied. INTERVENTIONS: Between two and four comparisons of lithium dilution cardiac output (LiDCO) and transpulmonary thermodilution (TPCO) were made in each patient. MEASUREMENTS AND RESULTS: Results from three patients were excluded: in one patient there was an unsuspected right-to-left shunt, in two patients there was a problem with blood sampling through the lithium sensor. There were 48 comparisons of LiDCO and TPCO in the remaining 17 patients over a range of 0.4-6 l/min. The mean of the differences (LiDCO-TPCO) was -0.1 +/- 0.3 (SD) l/min. Linear regression analysis gave LiDCO = 0.11 + 0.90 x TPCO l/min (r2 = 0.96). There were no adverse effects in any patient. CONCLUSIONS: These results suggest that the LiDCO method can be used to provide safe and accurate measurement of cardiac output in paediatric patients. The method is simple and quick to perform, requiring only arterial and venous catheters, which will already have been inserted for other reasons in these patients.

Cardiac output measured by lithium dilution, thermodilution, and transesophageal Doppler echocardiography in anesthetized horses.

OBJECTIVE: To assess the suitability of lithium dilution as a method for measuring cardiac output in anesthetized horses, compared with thermodilution and transesophageal Doppler echocardiography. ANIMALS: 6 horses (3 Thoroughbreds, 3 crossbreeds). PROCEDURE: Cardiac output was measured in 6 anesthetized horses as lithium dilution cardiac output (LiDCO), thermodilution cardiac output (TDCO), and transesophageal Doppler echocardiographic cardiac output (DopplerCO). For the LiDCO measurements, lithium chloride was administered i.v., and cardiac output was derived from the arterial lithium dilution curve. Sodium nitroprusside, phenylephrine hydrochloride, and dobutamine hydrochloride were used to alter cardiac output. Experiments were divided into 4 periods. During each period, 3 LiDCO measurements, 3 DopplerCO measurements, and 3 sets of 3 TDCO measurements were obtained. RESULTS: 70 comparisons were made between LiDCO, DopplerCO, and triplicate TDCO measurements over a range of 10 to 43 L/min. The mean (+/- SD) of the differences of LiDCO - TDCO was -0.86 +/- 2.80 L/min; LiDCO = -1.90 + 1.05 TDCO (r = 0.94). The mean of the differences of DopplerCO - TDCO was 1.82 +/- 2.67 L/min; DopplerCO = 2.36 + 0.98 TDCO (r = 0.94). The mean of the differences of LiDCO - DopplerCO was -2.68 +/- 3.01 L/min; LiDCO = -2.53 + 0.99 DopplerCO (r = 0.93). CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that lithium dilution is a suitable method for measuring cardiac output in horses. As well as being accurate, it avoids the need for pulmonary artery catheterization and is quick and safe to use. Monitoring cardiac output during anesthesia in horses may help reduce the high anesthetic mortality in this species.

A new technique for measuring cardiac output and shunt fraction during venovenous extracorporeal membrane oxygenation.

A new indicator dilution technique is described for measuring cardiac output and shunt fraction in patients undergoing venovenous extracorporeal membrane oxygenation (ECMO). Shunt fraction is the proportion of the ECMO pump flow which recirculates through the ECMO circuit (passing directly from the inflow cannula to the outflow cannula) instead of flowing through the pulmonary and systemic circulations. The indicator is an isotonic (150 mmol/l) solution of lithium chloride which is injected into the ECMO flow returning to the patient. Two lithium sensors are used simultaneously to record the resulting lithium dilution curves in arterial blood and in the blood in the ECMO circuit. Cardiac output and shunt fraction are derived from these curves. The techniques, which is simple and safe, provides measurements that allow optimal adjustment of ECMO flow and cardiovascular support.

A comparison of lithium dilution cardiac output measurements made using central and antecubital venous injection of lithium chloride.

OBJECTIVE: We have previously described an indicator dilution technique of measuring cardiac output in which lithium chloride is injected as a bolus via a central venous catheter and cardiac output derived from the arterial lithium dilution curve recorded from a lithium-selective electrode, which we have developed for this purpose. It would be an advantage if the lithium could be injected via the basilic vein (in the antecubital fossa) in those patients who do not need central venous catheterisation for other reasons. We have therefore compared cardiac output measurements made using these two routes of lithium chloride administration. METHODS: Lithium dilution cardiac output was measured 10 times in each of 10 patients, injecting the lithium chloride alternately via the basilic or central venous catheter. RESULTS: The mean difference was 0.8 +/- 5.2% (SD) (range -8.5 to +7.0%) over a range of cardiac output of 4.5-13 l/min. CONCLUSIONS: Injection of lithium chloride via the basilic vein in the antecubital fossa allows accurate lithium dilution cardiac output measurements to be made in patients who do not have central venous catheters in place.

The shape of indicator dilution curves used for cardiac output measurement in man.

1. In six patients arterial plasma lithium concentration-time curves were recorded following injection of lithium chloride into the right or left atrium. 2. Lognormal curve fitting was used to derive the areas under the first pass dilution curves. 3. Subjecting the curves produced by left atrial injection to a delay and sequential filtering produced curves that closely approximated those produced by right atrial injection. 4. We conclude that the transfer function of the right heart and lungs is equivalent to a delay and sequential filtering, that the primary indicator dilution curve is closely approximated by a lognormal curve and that loss of lithium in the lungs following right atrial injection is clinically insignificant.

Ambulatory blood pressure monitoring in a nonacademic setting. Effects of age and sex.

Twenty-four-hour ambulatory blood pressure measurements (ABPM) are likely to eliminate the stress of visits and observer bias in office blood pressure (BP) recordings, allow consideration of the circadian variability in BP, and correlate well with target organ damage. To define the prevalence of "white coat" hypertension in a rural community to a nonacademic setting, and to assess age and sex related differences, we studied 131 patients who had more than two prior office diastolic BP measurements greater than 90 mm Hg and less than 115 mm Hg. Blood pressure was measured every 10 to 60 min for 24 h using the SpaceLabs 90207 device. Office BP readings were higher than ABPM in the group as a whole, in individual age groups, and in both sexes. The differences were more pronounced at night. Average differences between office and ambulatory BP ranged between 14.4 +/- 1.7/2.9 +/- 2.0 (ABPM at 10:00), and 33.8 +/- 2.3/22.8 +/- 1.5 mm Hg (systolic/diastolic +/- SE) (ABPM at 01:00). The nighttime drop in systolic BP was not apparent in subjects more than 65 years old. Women had a proportionately higher mean office BP than men (115.0 +/- 0.9 office v 110.2 +/- 1.3 mm Hg ABPM in women and 112.3 +/- 0.9 v 104.3 +/- 1.1 mm Hg in men) (P = .013), and the elderly did not display the relationship between ambulatory and office mean BP seen in younger subjects (r = 0.15, P = .30 v r = 0.36, P = .0004, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperoxic lung injury and polyamine biosynthesis. Age-related differences.

To determine if lung cell replication and repair might be different between younger (30-day-old) and older (60-day-old) rats, we studied polyamine and DNA biosynthesis in rats exposed to 1.0 atm oxygen for 24, 48, 56, or 72 h. By 24 h, no statistically significant changes were observed, but by 48 h, ornithine decarboxylase and putrescine increased; S-adenosylmethionine decarboxylase activity increased by 56 h in the younger rats but not in the older rats. By 72 h, spermidine, [3H]thymidine incorporation, and the labeling index of cells in the alveolar zone had increased only in the younger rats. During the first 56 h, hyperoxia inhibited DNA synthesis. We conclude that hyperoxia initially suppresses lung cell replication but subsequently, if the rat survives, there are increases in polyamine biosynthesis and cell replication that may be important for the development of oxygen tolerance.

Immunological reactivity to a new glutaraldehyde tanned bovine pericardial heart valve.

The presence of pericardial specific antibodies directed against prosthetic bovine tissue heart valves was quantified by use of an indirect immunofluorescence technique. Serum samples containing antibodies displayed bright fluorescence when tagged with a secondary layer conjugated to FITC. Specific antibody production was undetectable in dogs or sheep who had undergone heart valve replacement (mitral or tricuspid) with a new unicusp prosthesis (Meadox Medicals Inc., NJ), as long as 17 mos following implantation. Similarly, anti-pericardial IgG was not detected in the serum of patients grafted with an analogous commercially available tissue heart valve, although in one patient the presence of low affinity IgM was suggested. This study documents the low immunological reactivity of this new tissue heart valve. Clinically valvular dysfunction due to an immunological response is not expected.

Polyamine metabolism in rat lungs with oxygen toxicity.

Ornithine decarboxylase activity increases 2-fold above control after 1 day and 25-fold after 3 days of exposure to 0.85 atm oxygen. Putrescine content nearly doubled by 72 hours which may reflect increased activity or ornithine decarboxylase. Spermidine and spermine content did not increase until after 3 days of exposure which was consistent with the delayed increase of S-adenosylmethionine decarboxylase activity. The results suggest that antimetabolites of polyamine metabolism may be useful to suppress excessive cellular proliferation in the lung after acute lung injury.

Recognition of marrow elements by natural killer cells: are NK cells involved in haemopoietic regulation?

NK cells from young normal mice are cytolytic in vitro for a virus-induced tumour cell line, YAC-1. Cytotoxicity is inhibited by the addition of unlabelled homologous YAC-1 cells and by regenerating bone marrow cells from the spleens of lethally irradiated, bone-marrow-grafted mice. Quiescent marrow from syngeneic and allogeneic mice produces little or no competition. This suggests that NK cells recognize, and may regulate, marrow progenitor cells.

Disappointment with triethers as markers for measuring triglyceride absorption in man.

Glycerol triethers were tried as non-absorbable, oil-phase markers for indirectly measuring triglyceride absorption in the human proximal jejunum. Tritium labelled 1-hexadecyl-2, 3-didodecyl glycerol, or 1,2,3-trioleyl glycerol, or 1,2,3-tridecyl glycerol was dissolved in linseed oil and egg yolk lipids; an aqueous emulsion of the lipid mixture was infused into the stomach. Unexpectedly, postprandial jejunal contents contained proportionately less triether than triglyceride compared with the test meals. These triethers were found to separate from an aqueous phase at a faster rate than the triglyceride. This dissociation occurred in the stomach and thwarted quantification of triglyceride absorption by this test system.