Goal-directed transesophageal echocardiography performed by intensivists to assess left ventricular function: comparison with pulmonary artery catheterization

OBJECTIVES

Transesophageal echocardiography (TEE) is a valuable procedure for assessing left ventricular (LV) function, but it has not been widely applied in critical care because of the limited number of intensivists who are trained in echocardiography. This prospective study was designed to evaluate the feasibility of training intensivists to perform a goal-directed, limited-scope TEE to assess LV function in critically ill patients using a pediatric monoplane TEE probe. A secondary goal was to compare the usefulness of the TEE data with that of data obtained by a simultaneous pulmonary artery catheter (PAC).

DESIGN

Prospective, blinded.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred consecutive, intubated, intensive care unit patients.

INTERVENTIONS

Five surgical intensivists with no previous background in echocardiography were trained under the supervision of two cardiologists to perform limited-scope TEE using a monoplane pediatric probe. One intensivist (A) reviewed the PAC data and recorded a diagnostic impression and therapeutic plan. A second intensivist (B), blinded to the PAC data, then performed TEE to determine cardiac volume, LV wall thickness, and LV global and regional wall motion. Intensivists A and B reviewed the data from both PAC and TEE, and intensivist A then formulated a new diagnosis and therapeutic plan.

MEASUREMENTS AND MAIN RESULTS

Intensivists performed 48 TEE examinations under direct supervision of a cardiologist, and 52 without supervision, but reviewed poststudy. The average duration of TEE was 12 +/- 7 minutes. The intensivists' interpretations of TEE data were deemed correct in 93% of cases for LV wall thickness, 87% for intracardiac volume status, 81% for regional LV wall motion abnormalities, and 77% for global LV function. When the TEE and PAC technologies were compared, it was found that the TEE data disagreed with the PAC evaluation of intracardiac volume in 55% of cases and with the PAC assessment of myocardial function in 39% of cases. The post-PAC therapeutic recommendations were different from the post-TEE therapeutic recommendations in 58% of patients.

CONCLUSIONS

Training intensivists in limited-scope, goal-directed TEE, using a pediatric monoplane probe to evaluate LV function, can be done rapidly and safely, and yield data pertinent to management of critically ill patients even in the early stages of skill acquisition.

Effects of the stable prostacyclin analogue iloprost on mesenteric blood flow in porcine endotoxic shock

OBJECTIVE

To determine the effects of the stable prostacyclin analog, iloprost, in a porcine model of endotoxin-induced mesenteric ischemia.

DESIGN

Prospective, experimental, randomized, controlled study.

SETTING

Animal research laboratory at a university medical center.

INTERVENTIONS

Pigs were randomized to receive a constant infusion of iloprost (0.18 microg/kg/min) or an equivalent amount of carrier solution (normal saline) 30 mins before being infused with endotoxin (100 microg/kg over 1 hr). The infusion with iloprost or carrier solution was continued for the duration of the experiment.

MEASUREMENTS AND MAIN RESULTS

Twelve pigs (six per group), weighing between 20 and 22 kg, underwent laparotomy during which a magnetic flowprobe was placed around the superior mesenteric artery and an ileal tonometer was inserted. Thirty minutes before they were infused with endotoxin, the animals were randomized to receive intravenous iloprost or normal saline. Endotoxin was infused centrally over a 60-min period. Animals received normal saline at a rate of 1.2 mL/kg/min which was begun at the start of the endotoxin infusion. Data were measured at the end of the endotoxin infusion (E60) and 1 hr later (E120). Mean arterial pressure was not affected by the dosage of iloprost used in this experiment. After resuscitation, the cardiac output returned to baseline in the iloprost-treated group but remained decreased in the control group (2.6 +/- 0.5 vs. 1.6 +/- 0.4 L/min). Superior mesenteric blood flow increased 34% above baseline levels in animals pretreated with iloprost (from 363 +/- 85 to 485 +/- 81 mL/min). The superior mesenteric PCO2 was significantly higher (53 +/- 9 vs. 40 +/- 5 torr; 7.1 +/- 1.2 vs. 5.3 +/- 0.7 kPa) and the ileal intramucosal pH was significantly lower (7.07 +/- .28 vs. 7.44 +/- .23) in the control group than in the iloprost-treated group.

CONCLUSIONS

Pretreatment with intravenous iloprost effectively increased intestinal blood flow in this model of endotoxin-induced mesenteric ischemia. This action of the drug resulted in an attenuation of ileal intracellular acidosis. Since low-dose iloprost had no effect on mean arterial pressure, it may be a useful adjunct in the treatment of sepsis and septic shock.

Continuous fiberoptic arterial and venous blood gas monitoring in hemorrhagic shock

STUDY OBJECTIVE

To compare the performance of continuous fiberoptic blood gas monitoring with standard, intermittent blood gas sampling in the measurement of arterial and central venous blood gases during marked hemodynamic changes.

DESIGN

Prospective, consecutive, enrollment, experimental study.

SETTING

Research laboratory at a university medical center.

PARTICIPANTS

Seven anesthetized, mechanically ventilated pigs.

INTERVENTIONS

Severe shock was induced by hemorrhage in pigs monitored by a pulmonary artery catheter, an arterial line, and two fiberoptic blood gas sensors: one intra-arterial, and the other inserted into the superior vena cava via right internal jugular vein cutdown. Fiberoptic blood gas monitor measurements were compared with standard intermittent blood gas sampling.

MEASUREMENTS AND RESULTS

A total of 184 blood gas samples were compared in seven animals at baseline, during shock, and after resuscitation. The baseline mean (+/- 1 SD) cardiac output decreased from 4.0 +/- 0.9 to 1.2 +/- 0.6 L/min during shock and returned to baseline after retransfusion (3.9 +/- 1.3 L/min). The comparison of continuous fiberoptic blood gas monitoring with intermittent blood gas sampling showed a bias+/-precision of 0.035 +/- 0.047 for arterial pH, 0.021 +/- 0.031 for central venous pH, -4.09 +/- 2.96 mm Hg (-0.55 +/- 0.39 kPa) for arterial Pco2, -3.67 +/- 2.44 mm Hg (-0.49 +/- 0.3 3 kPa) for central venous Pco2, -5.79 +/- 9.64 mm Hg (-0.77 +/- 1.29 kPa) for arterial Po2, and -7.85 +/- 8.52 mm Hg (-1.05 +/- 1.14 kPa) for central venous Po2.

CONCLUSIONS

Continuous fiberoptic blood gas monitoring agrees closely with standard intermittent blood gas sampling during severe hemodynamic shifts and has a comparable accuracy for both arterial and venous blood gas measurements. Changes in venous Pco2 have recently been shown to correlate with changes in global tissue perfusion (eg, changes in cardiac output). Such data, available immediately via continuous venous blood gas monitoring, may be useful for monitoring shock and the response to resuscitation.

Glutathione disulphide as a marker of reperfusion injury in ischaemic skin flaps

Estimation of the oxidised form of glutathione (GSSG) in an ischaemic/reperfused organ is frequently employed as an indicator of oxidative stress created by the production of oxygen free radicals during the reperfusion period. The time course of oxidative stress and tissue damage in 19 ischaemic/reperfused guinea-pig island skin flaps was evaluated. No-flow ischaemia was induced in the flaps for 6 h in 7 animals, and for 8 h in 9 animals (a further 3 animals served as controls without ischaemia). Arterial and venous blood samples were obtained directly from the flap pedicle at baseline, 10, 30, and 60 min following reperfusion. Results suggest that a second focus of oxidative injury, possibly mediated by activated neutrophils, contributes to the overall process of reperfusion injury. Plasma levels of GSSG allow for a more sensitive quantification of oxidant stress within reperfused ischaemic flaps, and may serve as a useful tool in skin flap research.

Endocrine function in the Klüver-Bucy syndrome: studies in adult female rhesus monkeys

Although the behavioral abnormalities of the Klüver-Bucy syndrome are well known, an investigation of the endocrine parameters had not been undertaken previously. The authors report normal reproductive cyclicity (including preserved feedback mechanisms) and growth hormone and cortisol secretion patterns in female rhesus monkeys with the syndrome. It is concluded that the abnormal behavior seen in the Klüver-Bucy syndrome is not associated with abnormalities of the reproductive mechanisms.