Air embolism: a potential complication of retrograde pyelography

We report 2 cases of venous air embolism as a complication of retrograde pyelography. The pyelovenous route of embolization was documented radiographically. The mechanisms of pyelovenous backflow are reviewed and the clinical implications of this phenomenon are discussed. Pyelovenous backflow may provide the mechanism for air embolism when gas is present in the urinary tract.     

Pyelorenal backflow during retrograde pyelography after renal transplantation.

Retrograde pyelography in 140 transplanted kidneys within 3 days of the operation showed a high frequency (29%) of pyelorenal backflow. Pyelotubular backflow, ordinarily a rare form of backflow, was seen in one-third of the patients whose transplants were removed within 60 days because of rejection, but in only 4% of the patients with surviving grafts. Pyelosinus backflow was found in 61% of the patients with signs of urinary obstruction, but in only 9% of the other patients. No relationship was found between pyelosinus backflow and graft rejection, or between pyelotubular backflow and urinary obstruction. Pyelotubular backflow may be an early radiographic sign of impending and serious rejection.     

Pyelolymphatic backflow complicating acute hemorrhagic cystitis: a case report]

The clinical course of a case of pyelolymphatic backflow complicated with acute hemorrhagic cystitis is reported. The patient was a 19-year-old woman. She had disturbed passage in the intravesical ureter due to acute hemorrhagic cystitis caused by adenovirus. Pyelolymphatic backflow occurred because of increased pelvic pressure.     

Pseudotumor of kidney

Pyelocancerous backflow during retrograde pyelography is a roentgen sign indicating renal tumors. An example of a pseudotumor (renal hematoma caused by anticoagulation) is presented which displayed this type of backflow, demonstrating the nonspecificity of the sign. The diagnostic, especially radiographic, findings of intrarenal hematoma are discussed.     

Effect of rotary blood pump failure on left ventricular energetics assessed by mathematical modeling

In this study, we used a mathematical model to study the influence of backflow through a failing rotary blood pump. We performed simulations based on animal experiments that were published earlier by Nishida et al., who used the Medos Microdiagonal pump to assess the acute effect of sudden pump failure. The mathematical model consists of validated cardiac and arterial modules and a pump module. We could evaluate the influence of pump failure with mechanoenergetic parameters and wall stress obtained from model output. Simulations were performed at baseline and after 15 min of backflow in a control group and a heart failure group. Simulation results agreed well with the experiment. Stroke volume, aortic flow, and stress time integral increased significantly because of pump failure. However, total systemic flow and arterial pressure were not altered by backflow, and a life-threatening situation did not appear.     

Mechanism preventing backflow from the canine corpora cavernosa to arteries in the rigid phase of penile erection.

The present study was performed in dogs to determine the site preventing the backflow from the corpus cavernosum to the arterial vessels when the corporeal pressure rises more than the systemic pressure (rigid phase). We confirmed a great gradient (325 +/- 81 mm Hg, mean +/- SD) between the corporeal pressure and the deep arterial pressure; the latter was measured at the distal point over the tunica albuginea, namely within the corpus cavernosum. This finding indicated that the mechanism preventing the arterial backflow existed within the corpus cavernosum. This assumption was supported by our light-microscopic findings that the helicine arteries were closed in the rigid phase, whereas they were dilated when the corporeal pressure was lower than the systemic pressure (tumescence/full erection phase). The results suggest that the helicine arteries play an essential role in the prevention of the arterial backflow in the rigid phase.     

Identification of an arteriovenous fistula during free tissue transfer despite negative preoperative angiography: a potentially correctable cause of venous thrombosis

Although refinements in microvascular technique have resulted in great success with free tissue transfer, long-term anastomotic patency, particularly venous, is less predictable in patients with a history of intravenous drug abuse or other causes of intimal damage and/or venous hypertension. We report an unusual case in which an arteriovenous fistula was identified intraoperatively as the cause of pulsatile venous backflow despite a normal preoperative angiogram. A flow disturbance at the site of venous anastomosis and subsequent development of a venous thrombosis prompted more proximal venous exposure and the identification of an arteriovenous fistula. Once ligated, pulsatile venous backflow resolved and successful revision of the venous anastomosis was performed. This case illustrates that an anomalous arteriovenous communication must be considered when high-pressure venous backflow is observed intraoperatively, despite no evidence of an arteriovenous fistula on preoperative angiography, because, if identified and ligated, an arteriovenous fistula may represent a treatable cause of venous thrombosis. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:72-75 1998     

A drainage bag (jelly bag) using a superabsorbent polymer: technical note

BACKGROUND: Various types of drainage bags for use after an operation are currently available, but they are often bulky, and backflow of contents can occur when the bag is not in the upright position. METHODS: As an alternative, we developed a drainage bag containing a superabsorbent polymer that becomes jelly-like as it absorbs the fluid. RESULTS: This bag is lightweight and compact for easy carrying, and there was no backflow, whatever its position. CONCLUSION: These features demonstrate a very useful drainage bag. This bag was remarkably useful for unconscious patients or for restless ones, particularly in the field of neurosurgery.     

Types of lymphoscintigraphy and indications for lymphaticovenous anastomosis

Several authors have reported the usefulness and benefits of lymphoscintigraphy. However, it is insufficient to indicate microvascular treatment based on lymphedema. Here, we present the relationships between lymphoscintigraphic types and indications for lymphatic microsurgery. Preoperative lymphoscintigraphy was performed in 142 limbs with secondary lymphedema of the lower extremity. The images obtained were classified into five types. Type I: Visible inguinal lymph nodes, lymphatics along the saphenous vein and/or collateral lymphatics. Type II: Dermal backflow in the thigh and stasis of an isotopic material in the lymphatics. Type III: Dermal backflow in the thigh and leg. Type IV: Dermal backflow in the leg. Type V: Radiolabeled colloid remaining in the foot. Lymphaticovenous anastomosis was performed in 35 limbs. The average number of anastomoses per limb was 3.3 in type II, 4.4 in type III, 3.6 in type IV, and 3 in type V. The highest number of anastomosis was performed in type III. In conclusion, type III is suggested to be the best indication for anastomosis compared with types IV and V.     

Case profile: Radiolucent urethral calculus with hemostatic clip nidus

Pyelosinus backflow with periureteral extravasation occurs not infrequently with acute ureteral obstruction. With a progressive film sequence its diagnosis is usually clear even in unusual situations, as described in this case report.     

A novel integrated rotor of axial blood flow pump designed with computational fluid dynamics

Due to the smaller size, smaller artificial surface, and higher efficiency, axial blood pumps have been widely applied in clinic in recent years. However, because of its high rotor speed, axial flow pump always has a high risk for hemolysis, which the red blood cells devastated by the shearing of tip clearance flow. We reported a novel design with the integrated blade-shroud structure that was expected to solve this problem by abolishing the radial clearance between blade and casing designed with the techniques of computational fluid dynamics (CFD). However, the numerical simulation result of the newly designed structure showed an unexpected backflow (where flow velocity is reverse of the main flow direction) at the blade tip. In order to eliminate this backflow, four flow passes were attempted, and the expansion angles (which reflect the radial amplification of the flow pass, on the meridional section, and should be defined as the angle between the center line of the flow pass and the axial direction) of the blades of the integrated rotor are 0 degrees, 8 degrees, 15 degrees, and 20 degrees, respectively. In the CFD result, it could be easily found as the expansion angles increased, the backflow was restrained gradually, and was eliminated at last. After numerous "cut and try" circles, the pump model was finally optimized. The numerical simulation of this model also showed a stable hydraulic characteristic.     

Characteristics and mechanism of pyelorenal backflow correlated to renal pelvic pressure

The present study was conducted to examine the characteristics of pyelo-renal backflow related with the changes in renal pelvic pressure. Forty rabbits weighting approximately 3.0 kg were used in this experiment. The renal pelvis was continuously perfused with PSP solution through the double lumen catheter placed above the ureteropelvic junction. The renal pelvic pressure was also recorded during the intrapelvic perfusion. Simultaneously, PSP concentrations in blood and urine excreted from the contralateral kidney were measured. During the intrapelvic perfusion with PSP solution, PSP blood concentration began to increase immediately and reached maximum within 1 or 2 minutes after a start of perfusion. Then, its concentration gradually decreased toward the constant, low levels. The urinary concentration of PSP showed the same change as the blood concentration with a time lag of 1 or 2 minutes. A compartment analysis showed that this backflow curve composed of an early phase and a late phase. The early phase was characterized by a rapid increase and following decrease (exponentially declining) in PSP concentration. The late phase was a portion of constant PSP concentration in the backflow curve. A maximum PSP concentration in the early phase was elevated with an increase in the increment rate of renal pelvic pressure. There was a significant, positive correlation between the maximum PSP urinary concentration and the increment rate of renal pelvic pressure (dp/dt). The constant values of PSP concentration in the late phase could be correlated with neither increment rate nor absolute values of renal pelvic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal function in experimental chronic hydronephrosis. II. Backflow studies with radionuclides.

Studies of backflow in experimental unilateral chronic hydronephrosis in dogs with a known residual renal function and renal pelvic volume were performed with radioactively labelled substances with molecular weights of ca. 600, 5 200 and 68 000 placed in the hydronephrotic renal pelvis. Three different pressure levels in the renal pelvis were used. Isotope concentrations were determined in the thoracic duct lymph, 0lood and urine from the contralateral kidney. The greater part of the test substances appeared to pass to the blood circulation, while a smaller part was found in the lymphatic ducts. The largest molecule, however, was only able to leave the renal pelvis to any appreciable extent at the highest pressure. In kidneys with a low grade of hydronephrosis and well preserved function, a relatively large amount of test substance left the renal pelvis (ca. 10-15%). In more advanced grades of hydronephrosis with greater impairment of renal function, the backflow was considerably less.     

Shape Optimization of the Diffuser Blade of an Axial Blood Pump by Computational Fluid Dynamics

Computational fluid dynamics (CFD) has been a viable and effective way to predict hydraulic performance, flow field, and shear stress distribution within a blood pump. We developed an axial blood pump with CFD and carried out a CFD‐based shape optimization of the diffuser blade to enhance pressure output and diminish backflow in the impeller–diffuser connecting region at a fixed design point. Our optimization combined a computer‐aided design package, a mesh generator, and a CFD solver in an automation environment with process integration and optimization software. A genetic optimization algorithm was employed to find the pareto‐optimal designs from which we could make trade‐off decisions. Finally, a set of representative designs was analyzed and compared on the basis of the energy equation. The role of the inlet angle of the diffuser blade was analyzed, accompanied by its relationship with pressure output and backflow in the impeller–diffuser connecting region.     

硬膜外注气对脊椎-硬膜外联合阻滞时腰穿的影响

目的 探讨硬膜外注气对脊椎-硬膜外联合阻滞时腰穿的影响.方法 拟在脊椎-硬膜外联合阻滞下行剖宫产术的足月单胎妊娠患者210例,ASA分级Ⅰ或Ⅱ级,年龄20～42岁,身高152～170 cm,体重57～82 kg,采用随机数字表法,将患者随机分为3组(n=70):悬滴法组(Ⅰ组)、少量注气组(Ⅱ组)和大量注气组(Ⅲ组).Ⅰ组以悬滴法验证硬膜外腔,Ⅱ组和Ⅲ组以注气试验验证硬膜外腔.Ⅱ组注气量以能感觉到阻力消失为准,Ⅲ组注气量为4 ml.置入腰穿针后见脑脊液回流则为腰穿成功.腰穿失败则改行硬膜外麻醉.记录腰穿成功情况、腰穿失败但硬膜外穿刺成功情况及不良反应发生情况.结果 Ⅰ组、Ⅱ组和Ⅲ组腰穿成功率分别为91%、93%和79%,Ⅰ组和Ⅱ组高于Ⅲ组(P<0.05),Ⅰ组和Ⅱ组间差异无统计学意义(P>0.05).所有腰穿失败患者均取得了双侧躯体节段性痛觉消失的硬膜外麻醉效果;所有腰穿成功患者也均取得了预期的麻醉效果.均未见严重不良反应发生.结论 硬膜外注气与脊椎-硬膜外联合阻滞时腰穿成功有关,大量注气可降低腰穿成功机率.

Abstract：

Objective To investigate the effect of injection of air into the epidural space on the subarachnoid puncture during the combined spinal-epidural anesthesia (CSEA) .Methods Two hundred and ten ASA Ⅰ or Ⅱ parturients who were at full term with a singleton fetus, aged 20-42 yr, weighing 57-82 kg (height 152-170cm) , undergoing cesarean section under CSEA, were randomly divided into 3 groups ( n = 70 each) : hanging drop technique group (group Ⅰ ) and injection of small volume of air group (group Ⅱ ) and injection of large volume of air group ( group Ⅲ ) . The epidural space was indentified using hanging drop technique in group Ⅰ and using loss of resistance to air technique in Ⅱ and Ⅲ groups. Injection of air was stopped as soon as the clear loss of resistance identified the epidural space in group Ⅱ , whereas all 4 ml of air was injected in group Ⅲ . After the epidural space was confirmed at L3,4 interspace, a 25-gauge spinal needle protruding 14 mm beyond the 18-gauge epidural needle was introduced through the epidural needle. Subarachnoid placement was confirmed by backflow of cerebrospinal fluid (CSF) . If no backflow of CSF was observed, the spinal needle was withdrawn and an epidural catheter was inserted through the epidural needle to perform epidural anesthesia. Successful subarachnoid puncture, failures to observe backflow of CSF and adverse reactions were recorded. Results The three groups were comparable with respect to age, height, body weight and gestation weeks. The success rate of subarachnoid puncture was 91% ,93% and 79% in Ⅰ ,Ⅱ and Ⅲ groups respectively, and it was significantly higher in Ⅰ and Ⅱ groups than in group Ⅲ ( P < 0.05) . There was no significant difference in the success rate of subarachnoid puncture between Ⅰand Ⅱ groups ( P > 0.05) . Bilateral segmental analgesia presented in all cases who received only epidural anesthesia after no backflow of CSF was observed, and the expected analgesia also presented in all cases in whom back flow of CSF was observed. No adverse reactions occurred. Conclusion Injection of air into the epidural space is related to the success of subarachnoid puncture during CSEA and injection of a large volume of air lowers the success rate.     

Unilateral hepatic duct obstruction in the primate

The effects of obstruction of one hepatic duct were investigated in two studies in the rhesus monkey. A model to divide bile flow from the two sides of the liver was developed in the first study. Bile flow from one side of the liver was obstructed and backflow from the obstructed biliary tract was investigated in five animals. Test solutions containing sulfobromophthalein (BSP) and conjugated cholic acid-14C were introduced into the obstructed side of the liver at pressures below and above the maximum secretory pressure. These solutes were detected in the circulation and in the bile on the free side of the liver. BSP, secreted on the free side, was conjugated normally (52.7 percent) for this species. There was also backflow of water from the obstructed side and continuing secretion into the obstructed side. It was determined that there were no functionally significant biliary communications between the two separately cannulated portions of the liver. In the second study, graded unilateral obstruction and recovery were studied in five animals. Bile flow, eyythritol-14C clearance, and bile acid, bilirubin, and bicarbonate secretion rates were reduced during obstruction and recovery. The bile:plasma ratio of erythritol-14C fell significantly (1.13 to 0.97) and the bicarbonate concentration increased during partial obstruction. On the free side, bile flow, erythritol-14C clearance, and bile acid secretion rates increased during obstruction. The increase in bile flow was due largely to an increase in canalicular bile acid-dependent flow. The studies indicated that reduced bile flow during acute obstruction is due to both hydrostatic backflow and secretory failure. The latter occurs mainly at the canalicular level, whereas the bile ductules are spared at least relatively. During acute obstructions compensations in unobstructed portions of the liver are due to increased secretion of solute at the canaliculus.     

Gastroduodenal artery steal syndrome during liver transplantation: intraoperative diagnosis with Doppler ultrasound and management

Arterial steal syndrome (ASS) after liver transplantation has been reported. ASS causes arterial hypo-perfusion of the graft liver and devastating consequences. However, the diagnosis tends to be delayed. We present the recognized case of a gastroduodenal artery (GDA) steal syndrome that was diagnosed with intraoperative Doppler ultrasound and treated with GDA ligation during the liver transplantation. The patient had variation of hepatic artery anatomy (low bifurcation of the hepatic artery). Graft liver had the common hepatic artery and aberrant left hepatic artery. Doppler ultrasound of the liver was performed after the arterial reconstruction between the donor common hepatic artery and recipient right hepatic artery. It showed low hepatic arterial flow. There is no backflow bleeding from the donor aberrant left hepatic artery stump. After ligating big GDA, hepatic arterial waveform inside the liver drastically improved and strong backflow bleeding was recognized from the donor left aberrant hepatic artery stump. The current case should show the efficacy of intraoperative Doppler ultrasound of the liver on ASS and alert clinician to ligate GDA to prevent ASS if hepatic arterial flows are suboptimal.     

Pyelocancerous backflow: a radiologic finding in renal malignancy.

Pyelocancerous backflow is a radiologic finding strongly suggestive of renal malignancy that has had little attention in the urologic literature. Its appearance is an ominous sign and, when present, renal adenocarcinoma invading the collecting system or infiltrating transitional cell carcinoma with parenchymal extension must be suspected. An illustrative case is presented and its significance is discussed.     

Vascular occlusion techniques during liver resection

Control of bleeding from the transected liver basically consists of vascular inflow occlusion and control of hepatic venous backflow from the caval vein. Central venous pressure determines the pressure in the hepatic veins and is an extremely important factor in controlling blood loss through venous backflow. Vascular inflow occlusion (Pringle maneuver) involves clamping of the portal vein and the hepatic artery in the hepatic pedicle and gives rise to postischemic, reperfusion injury. Several strategies have been devised to reduce reperfusion injury (pharmacological interventions) or to increase ischemic tolerance of the liver (ischemic preconditioning). Intermittent clamping is recommended in complex liver resections or in patients with diseased livers. The combination of occlusion of vascular inflow and outflow of the liver results in total hepatic vascular exclusion (THVE) and is mainly used in tumors invading the caval vein. During THVE the liver can be cooled by hypothermic perfusion allowing for extended ischemia times. Selective THVE entails clamping of the main hepatic veins in their extrahepatic course, thus preserving caval flow. Safe liver surgery requires knowledge of the regular techniques of vascular occlusion for 'on demand' use when necessitated to reduce blood loss.     

Simplified hepatic resections with the use of a Chang's needle

OBJECTIVE: To demonstrate the use of Chang's needle for hepatic resections. SUMMARY BACKGROUND DATA: Specialized instruments, fine surgical skills, and good control of hepatic inflow and backflow are essential for hepatic resections. This needle was specifically designed to simplify these requirements. METHODS: Whole-thickness interlocking sutures of the liver can first be made along the designed resection line with a Chang's needle; then parenchyma transection can follow without inflow or backflow control. This was consecutively performed on 69 patients with primary (41), metastatic (10), and benign (18) diseases since 1997. RESULTS: Blood loss during parenchyma transection was reduced in 11 right lobectomies (652 mL), 1 3-segmentectomy (300 mL), 14 bisegmentectomies (252 mL), 7 segmentectomies (104 mL), 12 subsegmentectomies (19 mL), 5 wedge resections (7 mL), 18 left lateral segmentectomies (110 mL), and 1 hepatorrhaphy (minimal). There was no procedure-related mortality. A mild bile leakage occurred in 1 case (1.5%) but healed spontaneously. CONCLUSIONS: The preliminary results demonstrate that this maneuver is a simple, easy, and safe method for performing hepatic resections.