Use of high-intensity focused ultrasound to control bleeding.
OBJECTIVE: High-intensity focused ultrasound (HIFU) has been shown to be effective in controlling hemorrhage from punctures in blood vessels. The objective of the current study was to investigate the capability of HIFU to stop bleeding after a more severe type of vascular injury, namely longitudinal incisions of arteries and veins. METHODS: The superficial femoral arteries, common femoral arteries, carotid arteries, and jugular veins of four anesthetized pigs were exposed surgically. A longitudinal incision, 2 to 8 mm in length, was produced in the vessel. HIFU treatment was applied within 5 seconds of the onset of the bleeding. The HIFU probe consisted of a high-power, 3.5-MHz, piezoelectric transducer with an ellipsoidal focal spot that was 1 mm in cross section and 9 mm in axial dimension. The entire incision area was scanned with the HIFU beam at a rate of 15 to 25 times/second and a linear displacement of 5 to 10 mm. A total of 76 incisions and HIFU treatments were performed. RESULTS: Control of bleeding (major hemosatsis) was achieved in all 76 treatments, with complete hemostasis achieved in 69 treatments (91%). The average treatment times of major and complete hemostasis were 17 and 25 seconds, respectively. After the treatment, 74% of the vessels in which complete hemostasis was achieved were patent with distal blood flow and 26% were occluded. The HIFU-treated vessels showed a consistent coagulation of the adventitia surrounding the vessels, with a remarkably localized injury to the vessel wall. Extensive fibrin deposition at the treatment site was observed. CONCLUSION: HIFU may provide a useful method of achieving hemostasis for arteries and veins in a variety of clinical applications. (+info)
Prolonged continuous or intermittent vascular inflow occlusion during hemihepatectomy in pigs.
OBJECTIVE: To assess ischemia and reperfusion (I/R) injury in a hemihepatectomy model in pigs after prolonged continuous or intermittent vascular inflow occlusion in the liver. SUMMARY BACKGROUND DATA: Massive intraoperative blood loss during liver resections can be prevented by temporary vascular inflow occlusion, consequently leading to ischemia and reperfusion injury in the remnant liver. Previously, in a pig liver resection model in which only limited I/R injury was induced during brief (90 min) vascular inflow occlusion, the authors demonstrated reduced I/R injury after continuous (CNT) occlusion, compared to intermittent (INT). This liver resection study on pigs was undertaken to assess I/R injury after prolonged (120 min) CNT or INT occlusion. METHODS: In pigs (37.0 +/- 1.5 kg), liver ischemia during 2 hours was CNT (n = 6) or INT (n = 6) (eight subsequent periods of 12 min ischemia and 3 min recirculation), followed by 6 hours of reperfusion. A left hemihepatectomy (45.5% +/- 1.4%) was performed within the first 12 minutes of ischemia. No hepatic pedicle clamping or liver resection was performed in control experiments (n = 6). Microvascular damage was assessed by hyaluronic acid (HA) uptake capacity of the liver (parameter of early sinusoidal endothelial cell damage) and restoration of intrahepatic tissue pO2 during reperfusion. Hepatocellular damage was tested by plasma concentrations of aspartate aminotransferase (AST), alanine aminotransferase, and lactate dehydrogenase (LDH). RESULTS: Hyaluronic acid uptake after 6 hours of reperfusion, compared to preischemic uptake, was unaltered in the control group, but was significantly reduced in both resection groups. However, more HA was taken up after INT occlusion, compared to CNT (60.4% +/- 5.6% and 39.5% +/- 3.7%, respectively; ANOVA: p = 0.001). Intrahepatic tissue pO2 distribution after 6 hours of reperfusion more closely returned to preischemic configuration in the INT group than in the CNT group, indicating reduced microcirculatory disturbances after INT occlusion. Release of AST and LDH after 6 hours of reperfusion was significantly increased in both CNT and INT groups. Lower AST levels, however, were found after INT occlusion than after CNT occlusion (267.0 +/- 74.7 U/l and 603.3 +/- 132.4 U/l, respectively; p = 0.06). CONCLUSIONS: Intermittent hepatic vascular inflow occlusion during prolonged liver ischemia in pigs resulted in less microcirculatory and hepatocellular injury, compared to continuous occlusion. Intermittent clamping is preferable when prolonged periods of vascular inflow occlusion are applied during liver resections. (+info)
Simultaneous bilateral total knee arthroplasty in a single procedure.
Eighty-eight consecutive patients undergoing total knee arthroplasty (TKA) were reviewed retrospectively and divided into two groups. Group I (64 patients) had both knees replaced simultaneously by one team in a single procedure while Group II (24 patients) had 2 operations staged about 7 days apart. The blood loss, operative time, knee functional score, period of hospitalisation and complications were documented in order to compare the 2 groups. Performing simultaneous bilateral TKA (Group I) did not increase the incidence of operative or post-operative complications. Equally, the functional score and mean intra- and post-operative blood loss were not influenced. The operative time and duration of hospitalisation were significantly shorter in Group I than in Group II. On the basis of the results of this study, it appears that simultaneous bilateral TKA is beneficial. (+info)
Non-invasive aortic blood flow measurement in infants during repair of craniosynostosis.
We have assessed the potential clinical benefit of a new echo-Doppler device (Dynemo 3000) which provides a continuous measure of aortic blood flow (ABF) using an aortic flowmeter and a paediatric oesophageal probe, during repair of craniosynostosis in infants under general anaesthesia. The data recorded included: ABFi (i = indexed to body surface area), stroke volume (SVi), systemic vascular resistance (TSVRi), pre-ejection period (PEP), left ventricular ejection time (LVET), mean arterial pressure (MAP), heart rate (HR) and central venous pressure (CVP). Data were collected: before (T1) and 3 min after skin incision (T2), at the time of maximal haemorrhage (T3) and at the end of the procedure (T4). Twelve infants (aged 7.0 (range 6-12) months) were included. ABFi, MAP and CVP were significantly lower at T3 compared with T1 (2.0 (0.8) vs 3.0 (0.8) litre min-1 m-2, 46.1 (5.8) vs 65.2 (8.9) mm Hg and 2.8 (1.6) vs 5.2 (2.1) mm Hg; P < 0.05). PEP/LVET ratio was significantly lower at T2 compared with T1 (0.25 (0.05) vs 0.30 (0.06)) and increased at T4 (0.36 (0.04); P < 0.05). These preliminary results suggest that this non-invasive ABF echo-Doppler device may be useful for continuous haemodynamic monitoring during a surgical procedure associated with haemorrhage in infants. (+info)
Effect of infiltration with ropivacaine on blood loss during reduction mammoplasty.
Ropivacaine is a new aminoamide local anaesthetic agent. Unlike other agents in its class, such as bupivacaine, it has been found to be vasoconstrictive. We have sought to investigate if this property is clinically useful and may reduce surgical blood loss. Reduction mammoplasty is a procedure in which considerable blood loss may occur. We have compared pre-incision infiltration of ropivacaine 75 mg in 0.9% saline 60 ml with the current practice of infiltration with bupivacaine 75 mg in 0.9% saline 60 ml and epinephrine (adrenaline) 5 micrograms ml-1. We studied five subjects; each received both solutions by infiltration, one to each breast, in random order and both the operating surgeon and anaesthetist were blind to the solution given. For data analysis, blood loss was expressed in ml/kg of tissue excised. There was no significant difference between the two regimens for duration of surgery or amount of tissue excised; however, ropivacaine was associated with markedly greater intraoperative blood loss than bupivacaine (median 696 (range 305-1366) ml kg-1 vs 300 (169-608) ml kg-1; P = 0.04, Wilcoxon rank sum test). Postoperative blood loss was not significantly different between groups (116 (14-173) ml kg-1 vs 98 (13-332) ml kg-1; P = 0.69, Wilcoxon rank sum test). We conclude that the vasoconstrictive properties of ropivacaine were not sufficiently great to merit its use as a sole agent for infiltration before reduction mammoplasty. (+info)
Randomised controlled trial of effect of terbutaline before elective caesarean section on postnatal respiration and glucose homeostasis.
AIM: To determine if terbutaline given to mothers before elective caesarean section facilitates neonatal respiration and metabolism. METHODS: A randomised controlled trial of 25 full term infants delivered by elective caesarean section was conducted. The mothers received a continuous infusion of terbutaline or saline 120-0 minutes before birth. Umbilical artery blood was collected at birth and analysed for blood gases and catecholamines. The lung function of each infant was assessed two hours after birth, and blood pressure, heart rate, blood glucose and body temperature were monitored until 24 hours of age. RESULTS: The infants of the treated mothers (n = 13) had significantly higher dynamic lung compliance (p < 0.001), lower airway resistance (p < 0.001), and respiratory frequency than control infants (n = 12). Blood glucose and adrenaline concentrations were significantly higher in the treated group (p = 0.0014 and p < 0.01). None of these infants had any clinical respiratory difficulties; there were two cases of transient tachypnoea in the control group. No negative side effects due to the terbutaline treatment were seen among the infants. The mothers felt no discomfort caused by the terbutaline infusion, although they bled more during surgery (p = 0.03). CONCLUSION: Stimulation of the beta adrenoceptors in utero with terbutaline infusion to the mothers promotes neonatal respiratory and metabolic adaptation after elective caesarean section. (+info)
Haemodynamic assessment of hypovolaemia under general anaesthesia in pigs submitted to graded haemorrhage and retransfusion.
We have compared the value of different variables used in the assessment of blood loss during progressive hypovolaemia and resuscitation under general anaesthesia in anaesthetized pigs. We measured mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), the negative component of the systolic arterial pressure variation (delta Down) and left ventricular end-diastolic area (LVEDa) using echocardiography. Blood was progressively withdrawn (up to 35 ml kg-1 in seven steps) and then reinfused after the same pattern. Regression coefficient (r) and normalized slope (nS) of the regression relationship between each variable and amount of blood loss were determined. The difference between the withdrawal and reinfusion curves was assessed by the area between the curves. We also estimated the minimal loss of blood volume which induced significant changes in each variable compared with that under control conditions during withdrawal of blood (minWBV) and maximal loss in blood volume which induced no significant changes in a variable compared with control conditions during retransfusion (maxRBV). During haemorrhage, MAP decreased (from mean 74 (SD 9) to 31 (5) mm Hg; P < 0.001), delta Down increased (from 1.2 (1.4) to 11.4 (4.2) mm Hg; P < 0.001), PCWP decreased (from 6.2 (2.1) to 0.3 (1.0) mm Hg; P < 0.001) and LVEDa decreased (from 13.8 (2.0) to 5.1 (2.0) cm2; P < 0.01). The highest r values were obtained with MAP and LVEDa, and the highest nS value with delta Down. The least difference between withdrawal and reinfusion was with LVEDa, the lowest values of minWBV were with PCWP and LVEDa, and the highest value of maxRBV was obtained with PCWP. During progressive haemorrhage under general anaesthesia, LVEDa was an accurate variable for assessment of blood volume loss, delta Down contributed no further information compared with MAP, and PCWP was the most reliable variable for assessing return to baseline blood volume. (+info)
Do obese patients bleed more? A prospective study of blood loss at total hip replacement.
This study compares blood loss at total hip replacement in obese and non-obese patients. We made a prospective study of intra-operative and postoperative blood loss in 80 consecutive primary cemented hip replacements. Patients' obesity was classified according to body mass index (BMI). Overall mean total blood loss was 1050 ml. Obese patients (BMI > 30) bled significantly more (P < 0.0001) than those of optimal weight (BMI < 26), whereas those overweight (BMI 26-30) did not. The mean excess blood loss in obese patients was 380 ml (95% confidence interval, 200-560 ml). At a time when the prevalence of obesity is increasing, this study quantifies the risks of greater blood loss with respect to obesity and aids informed consent. (+info)