Ultrasound recording of fetal breathing.

Apparatus for recording fetal chest wall movements is described. Special reference is made to technical considerations which can improve the quality of records obtained. Fetal breathing was observed in 44 out of 45 recordings. Maternal respiration and pulse could give rise to potentially confusing signals which were identified by recording these parameters on a separate channel.

A comparison of grey-scale image recording systems.

There is currently a rapid rise in the variety of image recording systems and recording media available for use with ultrasound and CT scanners. We have evaluated nine different systems and ten recording media and have compared their cost, convenience and performance. The choice of system in a particular department depends upon many factors, especially the number of images recorded and the reasons for recording them. We suggest that a busy department will probably require one of the more expensive automatic devices since these are the most convenient to use and have the lowest cost per image.

Real-time ultrasound. A new method for studying gall-bladder kinetics.

Real-time ultrasound has been found to be a satisfactory method for studying changes in gall-bladder size. It is superior to many other methods since it is non-invasive, harmless, and does not rely on the metabolism of a contrast agent. We have also found it easy to identify and compensate for changes in the gall-bladder axis. Rapid serial images are easily obtained and show similar contraction patterns to those resulting from conventional techniques.

Pancreatic ultrasound--a systematic approach to scanning technique.

The pancreas remains one of the more difficult organs to visualize but ultrasound can be successful in nearly 90% of patients. A systematic technique for identifying and delineating the pancreas is described and has been verified on over 500 patients to date. The success of the technique depends on an accurate knowledge of the vascular relations of the pancreas and on correct adjustment of the ultrasound equipment. This paper is intended to help ultrasound practitioners achieve both these ends.

Hepatic vein pulsatility assessment on spectral Doppler ultrasound.

Hepatic vein pulsatility correlates with the severity of disease in a range of different liver disorders. We describe a simple visual grading system for scoring hepatic vein pulsatility which does not require any on-screen measurements and which has proved reproducible in clinical practice. The system gives a six point score for the waveform pulsatility, 6 being a normal value and 1 indicating a complete lack of modulation.

Preparation of the patient for abdominal ultrasound scanning.

The value of dietary restriction and laxatives both separately and in combination for the reduction of bowel gas has been investigated and compared with unprepared patients. No significant difference was found between the results from prepared and un-prepared patients.

Duplex Doppler ultrasound in the diagnosis of cavernous transformation of the portal vein.

Duplex Doppler ultrasound scans were performed in 10 patients with proven cavernous transformation of the portal vein. All cases exhibited absence of the normal portal vein lumen with replacement by numerous tortuous vessels. Doppler studies revealed a characteristic "flat" waveform with a reduction in the time averaged velocity to less than 8 cm/s which is well below the normal range. The combination of real-time and Doppler ultrasound enabled an accurate diagnosis to be made in all cases.

Comparison of ultrasound and computer-assisted tomography in pancreatic diagnosis.

In a series of patients suspected of having pancreatic disease both ultrasound and computerized tomography (CT) were performed. The diagnosis has been confirmed in 50 patients. Computerized tomography visualized the pancreas in all 50 (100%) whereas ultrasound was successful in 40 patients (80%). The ultrasound failures were due to bowel gas anterior to the pancreas. The overall diagnostic accuracy was 84% for computerized tomography and 64% for ultrasound; however, in those cases where ultrasound successfully detected the pancreas the diagnostic accuracy was 80%.

Ultrasound of the hip: a review of the applications of a new technique.

In an attempt both to reduce gonadal irradiation incurred with conventional radiology, and to image the unossified structures of the neonatal hip, several groups have undertaken studies on aspects of hip ultrasound particularly with reference to the paediatric patient. The ultrasound anatomy of the unossified infant hip has been described by Graf in Austria. The same author has devised an ultrasonographic classification for hip dysplasias and dislocations which has gained widespread acceptance in mainland Europe. Two studies have appeared exploring the use of ultrasound for the measurement of femoral neck anteversion but as yet these have not been compared with CT or trigonometric methods of assessment. Ultrasound has been shown to be effective in the detection of hip joint effusions, but its role in the management of the "irritable hip" has yet to be defined.

Ultrasound features of the gall bladder in infants presenting with conjugated hyperbilirubinaemia.

An initial investigation of 313 patients suggested that the ultrasound appearances of gall bladder shape and wall structure might be abnormal in infants with biliary atresia. These observations were then tested in a prospective study. In this study, 346 infants, aged 12 weeks or less, presenting with conjugated hyperbilirubinaemia underwent ultrasound scanning. The gall bladder was identified in 331, 60 of whom had biliary atresia. 11 of the 15 patients in whom the gall bladder was not seen had biliary atresia. Gall bladder shape was normal in 272 patients, 16 of whom had biliary atresia, and irregular in 59, 44 of whom had biliary atresia. The gall bladder wall was regular in 262 patients, 8 of whom had biliary atresia, and irregular in 69, 52 of whom had biliary atresia. Combining these findings gave a sensitivity of 90%, a specificity of 92.4%, a positive predictive value of 75.3%, a negative predictive value of 97.3% and an accuracy rate of 91.9% for ultrasound of the gall bladder in identification of biliary atresia.

Ultrasound diagnosis of portocaval anastomosis in infants--a report of eight cases.

We report eight cases of portocaval anastomosis in infants diagnosed by ultrasound. Anatomically we believe this represents continuing patency of the ductus venosus, either as a primary developmental abnormality or secondary to established liver cell failure.

Improved diagnosis of extraheptic biliary atresia by high frequency ultrasound of the gall bladder.

Ultrasound scanning using a 13 MHz probe was performed on 158 infants, aged 12 weeks or less, presenting with conjugated hyperbilirubinaemia. The gall bladder was identified in 156 infants, 35 of whom had biliary atresia. The two patients in whom no gall bladder was seen both had biliary atresia. The gall bladder shape was normal in 128 patients (9 with biliary atresia) and irregular in 28 patients (26 with biliary atresia). The gall bladder wall was regular in 121 patients (4 with biliary atresia) and irregular in 35 patients (31 with biliary atresia). Combining these findings gave a sensitivity of 91.9%, a specificity of 96.7%, a positive predictive value of 89.5%, a negative predictive value of 97.5% and an accuracy rate of 95.6% for ultrasound of the gall bladder in the identification of biliary atresia. This compares with 90%, 92.4%, 75.3%, 97.3% and 91.9%, respectively, in our previous report using a 7 MHz probe.

The value of serial Doppler ultrasound as a predictor of clinical outcome and the need for transplantation in fulminant and severe acute liver failure.

The aim of this study was to document the changes in Doppler ultrasound variables of the hepatic artery and portal vein in fulminant and severe acute liver failure, and to assess their prognostic significance. 18 adult patients with fulminant and severe acute liver failure underwent serial Doppler sonography, in the early stages after presentation. 12 hourly measurements of hepatic artery resistance index (HARI), spleen length, portal vein cross-sectional area, time average velocity (TAV) and flow volume were performed. Mean HARI (p = 0.03) and mean maximum HARI (p = 0.03) were significantly higher in those who fulfilled criteria for liver transplantation. Increased portal vein flow was demonstrated, although the difference between the groups was not significant. A significant increase in portal vein cross-sectional area (p < 0.02) and spleen length (p < 0.02) was demonstrated. In summary, an increase in portal blood flow to the damaged liver has been demonstrated. The mean HARI is significantly higher in patients who fulfil transplant criteria and may possibly be used as an indicator of poorer prognosis and the need for liver transplantation in acute severe and fulminant liver failure.

Variability of Doppler ultrasound measurements of hindlimb blood flow in conscious horses.

Ultrasonography of the left and right femoral artery and vein was performed in 5 conscious horses. Velocity waveforms, recorded using low pulse repetition frequency, were used to calculate time-averaged mean velocity (TAV), velocity of component a (TaVa), velocity of component b (TaVb) and volumetric flow. Waveform analysis included calculation of early diastolic deceleration slope (EDDS) and pulsatility index (PI) and subjective description of the waveform. Measurements were recorded at monthly intervals for 6 months. The repeated measurements were used to determine the within-horse variation. Horses were then anaesthetised with halothane and the same measurements recorded 60 min after induction. Differences between measurements recorded in conscious and anaesthetised horses were determined. Within-horse variability for diameters of femoral arteries and veins was small (CV<10%). Within variability for all other measurements was marked (CV>11%), with within-horse variability being the largest for femoral venous flow (CV>35%). Source of variability was measurement error and biological variation. Despite variability in conscious horses it was possible to detect changes in blood flow during anaesthesia. In the femoral arteries, volumetric flow was lower and EDDS and PI was higher in anaesthetised horses. In the femoral veins, volumetric flow was also lower in anaesthetised horses. Therefore Doppler ultrasound appears to be a useful technique for studying blood flow in conscious and anaesthetised horses.

A comparison of the haemodynamic effects of isoflurane and halothane anaesthesia in horses.

The purpose of this study was to compare the haemodynamic effects of equipotent isoflurane and halothane anaesthesia. Six adult horses were investigated on two separate occasions at least 4 weeks apart. On both occasions anaesthesia was induced by ketamine 2.2 mg/kg bwt given 5 min after i.v. administration 100 microg/kg bwt romifidine. Anaesthesia was maintained either by halothane or isoflurane (end-tidal concentrations 0.9-1.0% and 1.3-1.4%, respectively). Horses were ventilated by intermittent positive pressure to maintain PaCO2 between 40-50 mmHg. Haemodynamic variables were measured using catheter-mounted strain gauge transducers in the left and right ventricle, aorta, and right atrium. Cardiac output (CO), velocity time integral (VTI), maximal aortic blood flow velocity (Vmax) and acceleration (dv/dt(max)), left ventricular pre-ejection period (PEP) and ejection time (ET) were measured from aortic blood flow velocity waveforms obtained by transoesophageal Doppler echocardiography. Flow velocity waveforms were recorded from the femoral arteries and veins using low pulse repetition frequency Doppler ultrasound. Time-averaged mean velocity (TAV), velocity of component a (TaVa), velocity of component b (TaVb) and early diastolic deceleration slope (EDDS) were measured. Pulsatility index (PI) and volumetric flow were calculated. Microvascular blood flow was measured in the left and right semimembranosus muscles by laser Doppler flowmetry. Maximal rate of rise of LV pressure (LVdp/dt(max)), CO, Vmax, dv/dt(max), ET, VTI were significantly higher at all time points during isoflurane anaesthesia compared to halothane anaesthesia. Pre-ejection period and diastolic aortic blood pressure were significantly less throughout isoflurane anaesthesia compared to halothane. Isoflurane anaesthesia was associated with significantly lower systemic vascular resistance than halothane anaesthesia. Femoral arterial and venous blood flow were significantly higher and EDDS and PI were significantly lower during isoflurane anaesthesia compared to halothane anaesthesia. In addition during both halothane and isoflurane anaesthesia, femoral arterial flow was higher and EDDS and PI lower in the left (dependent) artery compared to the right (nondependent) artery. This study supports previous work demonstrating improved left ventricular systolic function during isoflurane compared to halothane anaesthesia. This improvement was still evident after premedication with a potent-long acting alpha2-adrenoreceptor agonist, romifidine, and induction of anaesthesia with ketamine. There was also evidence of increased hindlimb blood flow during isoflurane anaesthesia. However, there were differences observed in flow between the left and right hindlimb during maintenance of anaesthesia with each agent, suggesting that there were differences in regional perfusion in anaesthetised horses caused by factors unrelated to agents administered.

Effect of a 30-minute infusion of dobutamine hydrochloride on hind limb blood flow and hemodynamics in halothane-anesthetized horses.

OBJECTIVE: To evaluate the hemodynamic effects of dobutamine hydrochloride (0.5 microg/kg of body weight/min) in halothane-anesthetized horses. ANIMALS: 6 adult Thoroughbred horses. PROCEDURE: Anesthesia was induced by use of romifidine (100 microg/kg) and ketamine (2.2 mg/kg), IV. Anesthesia was maintained by halothane (end-tidal concentration 0.9 to 1.0%). Aortic, left ventricular, and right atrial pressures were measured, using catheter-mounted strain gauge transducers. Cardiac output (CO), velocity time integral, maximal aortic blood flow velocity and acceleration, and left ventricular preejection period and ejection time were measured from aortic velocity waveforms obtained by transesophageal Doppler echocardiography. Velocity waveforms were recorded from the femoral vessels, using Doppler ultrasonography. The time-averaged mean velocity and early diastolic deceleration slope (EDDS) were measured. Pulsatility index (PI) and volumetric flow were calculated. Microvascular perfusion was measured in the semimembranosus muscles by laser Doppler flowmetry. Data were recorded 60 minutes after induction of anesthesia (control) and at 15 and 30 minutes after start of an infusion of dobutamine (0.5 microg/kg/min). RESULTS: Aortic pressures were significantly increased during the infusion of dobutamine. No change was observed in the indices of left ventricular systolic function including CO. Femoral arterial flow significantly increased, and the PI and EDDS decreased. No change was observed in the femoral venous flow or in microvascular perfusion. CONCLUSIONS AND CLINICAL RELEVANCE: At this dosage, dobutamine did not alter left ventricular systolic function. Femoral blood flow was preferentially increased as the result of local vasodilatation. The lack of effect of dobutamine on microvascular perfusion suggests that increased femoral flow is not necessarily associated with improved perfusion of skeletal muscles.