Wedge pressure in large vs. small pulmonary arteries to detect pulmonary venoconstriction

Pulmonary arterial wedge pressure measures the pressure where blood flow resumes on the venous side. By occlusion of a large artery, the point where blood flow resumes will be in or near the left atrium. However, by occlusion of a small artery, it is possible to shift the point where flow resumes to a more proximal site in the veins and thus measure a pressure within the small veins. Increased pulmonary venous pressure, as a result of partial obstruction in the large veins, may not be detected by wedging a Swan-Ganz catheter in a large artery but may be detected by wedging in a small artery. We demonstrated this phenomenon in open-chest dogs by mechanically obstructing the left lower lobar vein or by infusing histamine to cause a generalized pulmonary venoconstriction. The wedge pressure measured by a 7-F Swan-Ganz catheter, with its balloon inflated in the main left lower lobar artery, nearly equaled left atrial pressure. On the other hand, the wedge pressure measured with a 7-F, 5-F, or a PE-50 catheter advanced into a small artery (without a balloon) was considerably higher than left atrial pressure. These results suggest that high resistance in the pulmonary veins can be demonstrated with the Swan-Ganz catheter by comparing the pressures obtained with the catheter wedged in a small and large artery.     

An Aortic Tampon for Emergency Control of Ruptured Abdominal Aneurysm

Ruptured abdominal aneurysm has now become a common surgical emergency, frequently amenable to successful resection and cure. The final result is often marred, however, by the effects of renal, coronary or cerebral ischemia resulting from dangerous hypotension during transportation of the patient to a vascular centre.An aortic catheter has been developed which is passed by way of a brachial artery cut-down so that it rests in the abdominal aorta. The balloon at its tip is then filled with sodium diatrizoate (Hypaque) so that it completely obstructs the aortic lumen just above the level of the aneurysm. Accurate positioning of the balloon to carefully preserve renal blood flow is facilitated by fluoroscopic control. The use of this procedure in three patients has been very satisfactory, with a dramatic return of consciousness and of normal blood pressure, without the need for further blood replacement. Subsequent surgery with dissection of the aneurysm was aided by the presence of the palpable inflated balloon.     

Removal of esophageal foreign bodies with a Foley balloon catheter under fluoroscopic control.

Between 1982 and 1985 removal of a nonorganic, smooth, radiopaque foreign body in the esophagus with a Foley balloon catheter under fluoroscopic control without sedation was attempted in 38 children. An ultra-low-dose fluoroscopic unit was used. In 35 children the foreign body (a coin) was either easily removed (in 29 cases) or advanced into the stomach (in 6). No complications of the procedure were observed. In three children the foreign body could not be removed by this means; it was subsequently removed by endoscopy (in two cases, both of coins) or esophagotomy (in two cases, both of coins) or esophagotomy (in one, of a stone). When carefully performed, removal of blunt, recently ingested esophageal foreign bodies with a Foley catheter under fluoroscopic control is a safe mode of treatment.     

Pulmonary hypertension induced with an intra-arterial balloon: an alternate mechanism

The Laks catheter is a triple-lumen balloon catheter used to distend the canine main pulmonary artery while recording right ventricular pressure and the arterial pressure distal to the balloon. A rise in arterial pressure reported to occur during distension has been attributed to vasoconstriction rather than passive obstruction by the balloon. We tested this in six anesthetized dogs by inflating the Laks catheter-balloon while recording pressure distal to the balloon from the Laks catheter as well as from additional catheters in right and left pulmonary arteries placed retrogradely through lobar branches following thoracotomy. We found that balloon inflation increased pressures in the arterial port of the Laks catheter and in the left pulmonary artery catheter but reduced it in the right pulmonary artery. Tightening a snare around the right pulmonary artery had the same effects on pressures. Similar results were obtained while cardiac output was controlled by left ventricular bypass perfusion in four dogs. We conclude that the Laks catheter-balloon obstructs flow to the right lung and that the arterial pressure rise recorded in it during balloon inflation cannot be distinguished from that caused by occlusion of the right pulmonary artery.     

Calculation of dose distribution near an innovative concentric balloon catheter for endovascular brachytherapy

Purpose: Using a radioactive solution-filled catheter for intravascular irradiation has the potential problem of chemical and radiological toxicity in the case of a balloon rupture. In order to reduce this risk, an innovative concentric balloon catheter was developed.Methods and Materials: The concentric balloon was made by inner and outer balloons filled with saline and radioactive solution, respectively. The optimal inner radius was determined by comparing the dose rate reduction vs. the volume reduction for various inner and outer radii for 188Re, 32P, and 90Y solutions.Results: For a balloon with an outer radius of 1.5 mm, there was no advantage of a concentric balloon. For balloons with outer radii of 3.0 and 5 mm, the optimal inner radius was 1.5 and 3 mm, respectively.Conclusions: With the newly designed concentric balloon, the risk of toxicity can be reduced while keeping the dose rate high enough so that the treatment times within tolerable limits are still maintained.     

A simple model for describing pressure-volume curves in free balloon dilatation with reference the dynamics of inflation hydraulic aspects]

We propose a simple model to describe pressure-time and pressure-volume curves for the free balloon (balloon in air) of balloon catheters, taking into account the dynamics of the inflation device. On the basis of our investigations of the flow rate-dependence of characteristic parameters of the pressure-time curves, the appropriateness of this simple model is demonstrated using a representative example. Basic considerations lead to the following assumptions: (1) the flow within the shaft of the catheter is laminar, and (ii) the volume decrease of the liquid used for inflation due to pressurization can be neglected if the liquid is carefully degassed prior to inflation, and if the total volume of the liquid in the system is less than 2 ml. Taking into account the dynamics of the inflation device used for pumping the liquid into the proximal end of the shaft during inflation, the inflation process can be subdivided into the following three phases: initial phase, filling phase and dilatation phase. For these three phases, the transformation of the time into the volume coordinates is given. On the basis of our model, the following parameters of the balloon catheter can be determined from a measured pressure-time curve: (1) the resistance to flow of the liquid through the shaft of the catheter and the resulting pressure drop across the shaft, (2) the residual volume and residual pressure of the balloon, and (3) the volume compliance of the balloon catheter with and without the inflation device.     

Balloon catheter dilatation and thrombectomy for acute aortoiliac occlusion

A case of acute distal aortic thrombosis in an elderly high-risk patient was successfully managed with intraoperative thrombectomy and balloon catheter dilatation of the common iliac arteries. Balloon catheter dilatation may be indicated prior to bypass grafting in high-risk patients with acute aortoiliac thrombosis.     

Intrapulmonal dislocation of a totally implantable venous access device

BACKGROUND: Totally implantable venous access devices are widely used for infusion of chemotherapy or parenteral nutrition. Device associated complications include technical operative problems, infections, paravasal infusions and catheter or punction chamber dislocation. CASE PRESENTATION: We present the case of a 49-year-old patient with the rare complication of a intrapulmonal catheter dislocation of a totally implantable venous access system. Treosulfane for chemotherapy of metastatic breast cancer was infused via the catheter causing instant coughing and dyspnoea which lead to the diagnosis of catheter dislocation. The intrapulmonal part of the catheter was removed under thoracoscopic control without further complications. CONCLUSION: Intrapulmonal catheter dislocation is a rare complication of a totally implantable venous access device which can not be avoided by any prophylactic measures. Therefore, the infusion system should be tested before each use and each new symptom, even when not obviously related to the catheter should be carefully documented and evaluated by expert physicians to avoid severe catheter-associated complications.     

Numerical study of the uniformity of balloon-expandable stent deployment

Stents are small tubelike structures, implanted in coronary and peripheral arteries to reopen narrowed vessel sections. This endovascular intervention remains suboptimal, as the success rate is limited by restenosis. This renarrowing of a stented vessel is related to the arterial injury caused by stent-artery and balloon-artery interactions, and a local subsequent inflammatory process. Therefore, efforts to optimize the stent deployment remain very meaningful. Several authors have studied with finite element modeling the mechanical behavior of balloon-expandable stents, but none of the proposed models incorporates the folding pattern of the balloon. We developed a numerical model in which the CYPHER stent is combined with a realistic trifolded balloon. In this paper, the impact of several parameters such as balloon length, folding pattern, and relative position of the stent with respect to the balloon catheter on the free stent expansion has been investigated. Quantitative validation of the modeling strategy shows excellent agreement with data provided by the manufacturer and, therefore, the model serves as a solid basis for further investigations. The parametric analyses showed that both the balloon length and the folding pattern have a considerable influence on the uniformity and symmetry of the transient stent expansion. Consequently, this approach can be used to select the most appropriate balloon length and folding pattern for a particular stent design in order to optimize the stent deployment. Furthermore, it was demonstrated that small positioning inaccuracies may change the expansion behavior of a stent. Therefore, the placement of the stent on the balloon catheter should be accurately carried out, again in order to decrease the endothelial damage.     

Static and dynamic operating characteristics of a pericardial balloon.

Previously, we developed a balloon transducer to measure the constraint of the pericardium (i.e., pericardial pressure) on the surface of the heart. It was validated physiologically in that it was shown to measure a pressure equal to the difference between the left ventricular end-diastolic pressure measured before and after pericardiectomy at the same left ventricular volume. To define its static operating characteristics, we loaded the balloon nonuniformly with weights that covered fractions of the balloon surface and found that the balloon accurately recorded the average stress if the stress was applied over at least 23% of its surface. To test its performance when curved, we placed it in large and small cylinders (minimum diameter 31 mm) and found that the balloon accurately recorded the stress. To define its dynamic operating characteristics, we applied sinusoidal stresses and found that its frequency response was limited only by that of the connecting catheter. When better dynamic response is required, we introduce a micromanometer-tipped catheter to obtain a unity-gain frequency response that is flat to 200 Hz.     

Cryoballoon ablation for atrial fibrillation

Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy.     

Study of the mechanism of rectal motility: the 'mass squeeze contraction'

The motor physiology of the rectum has remained largely obscure, especially concerning the mechanism of rectal motility. In the current communication we tested the possibility of characterizing the mechanism of rectal motility during filling and evacuation through the study of the rectal electric activity in 16 healthy volunteers (mean age 43.6 +/- 10.8 years; 11 men). Two monopolar silver-silver chloride electrodes were introduced per annum and fixed to the rectal mucosa by suction. The rectum was distended in 10 ml increments of water by means of a balloon-ended catheter inserted into the rectum. The rectal pressure was measured by one catheter placed above and a second one below the rectal balloon, and the 2 catheters were connected to 2 strain gauge pressure transducers. Regular triphasic slow waves or pacesetter potentials (PPs) were recorded from the 2 electrodes at rest. PPs were superimposed or followed randomly by action potentials (APs). APs but not PPs were coupled with elevated rectal pressure. Rectal distension with 10 ml of water caused no significant changes of the rectal pressure or EMG activity. Distension with a mean volume of 27.3 +/- 4.7 ml effected a significant increase (p < 0.05) of the rectal electromechanical activity proximally to the balloon and a decrease distally (p < 0.05) to it. With progressive increase of the rectal distension, the electromechanical activity continued to increase proximally and to decrease distally to the balloon, until, at a mean distending volume of 76.3 +/- 3.7 ml, the balloon was dispelled to the exterior. In conclusion, the identification of the modality of rectal motility during defecation was feasible by recording the rectal electromechanical activity. The rectal contraction is suggested to occur in a 'mass squeeze manner' which squeezes the rectal contents aborally into the anal canal. The recognition of the rectal motor modality appears to be important for the understanding of rectal motility disorders. However, further studies are required to confirm these findings.     

SURGICAL DECOMPRESSION OF THE BOWEL IN PERITONITIS

In some circumstances peritoneal infection causes distention and crowding of the bowel to such an extent that the effect is that of intestinal obstruction and it is impossible to introduce a tube far enough by physiologic routes to bring about deflation. The pressure upon the diaphragm then may cause pain in breathing, with the result that the patient does not fully expand the lungs and atelectasis develops in the lower lobes. In such circumstances surgical intervention to relieve the pressure in the bowel may be indicated.An ordinary urethral catheter introduced through an incision in the intestine cannot be extended far enough to relieve pressure in more than a few loops.A method of using a Foley catheter and of advancing it for greater distances inside the bowel was used in five cases with good results and without complications.     

A comparison of changes in esophageal pressure and regional juxtacardiac pressures

The relationship between esophageal pressure and juxtacardiac pressures was studied during positive end-expiratory pressure (PEEP) ventilation applied to both lungs or selectively to one lung. The experiments were performed in eight anesthetized dogs with balloon catheters in the esophagus and in the left and right pericardial and overlying pleural cavities and with an open-ended liquid-filled catheter in the pleural cavity. Bilateral PEEP (10, 20, and 30 cmH2O) caused progressive and similar increments in left and right pleural pressure. Selective PEEP, however, increased ipsilateral pleural balloon pressure more than contralateral pressure. The increase in ipsilateral pleural balloon pressure markedly exceeded the increase in esophageal pressure. There was a small increase in pleural open-ended catheter pressure that approximated the increase in esophageal pressure. During selective PEEP, pericardial balloon pressure remained uniform because of a decrease in ipsilateral pericardial transmural pressure. In conclusion, selective PEEP caused nonuniform increments in regional pleural balloon pressure. Left and right pericardial balloon pressure, however, increased uniformly with selective PEEP because of reduced ipsilateral pericardial transmural pressure. The esophageal balloon did not reflect the marked regional increments in pleural balloon pressure with selective PEEP and consistently underestimated the changes in pleural balloon pressure with general PEEP.     

Early development of bacterial community diversity in emergently placed urinary catheters

ABSTRACT: BACKGROUND: Approximately 25% of hospitalized patients have a urinary catheter, and catheter associated urinary tract infection is the most common nosocomial infection in the US, causing >1 million cases/year. However, the natural history of the biofilms that rapidly form on urinary catheters and lead to infection is not well described. FINDINGS: We characterized the dynamics of catheter colonization among catheters collected from 3 women and 5 men in a trauma burn unit with different indwelling times using TRFLP and culture. All patients received antibiotic therapy. Results: Colony-forming units increased along the extraluminal catheter surface from the catheter balloon to the urethra, but no trend was apparent for the intraluminal surface. This suggests extraluminal bacteria come from periurethral communities while intraluminal bacteria are introduced via the catheter or already inhabit the urine/bladder. Richness of operational taxonomic units (OTUs) increased over time on the intraluminal surface, but was constant extraluminally. CONCLUSIONS: OTU community composition was explained best by time rather than axial location or surface. Our results suggest that catheter colonization can be very dynamic, and possibly have a predictable succession.     

The evolution of the treatment of isolated pulmonary valve stenosis

In the course of studies covering 40 years, 1913 to 1953, leading to the development of cardiopulmonary bypass, many ingenious blind instrumental or digital intrusions were made into the heart chambers to treat lesions therein. Limits were defined for the arrest of circulation through part or all of the heart to permit a brief glimpse of the lesion and effect at least a partial correction. The often remarkably good results of operations performed under less than ideal operating conditions for lesions such as isolated pulmonary stenosis encouraged the interventional cardiologist and radiologist, working together, to adapt the cardiac catheter, used previously for exploration of the vascular system and diagnosing intravascular lesions, to therapeutic purposes. They positioned a catheter with uninflated balloon attached in the pulmonary artery, then either by inflating the balloon beyond the constricted orifice and pulling it through or by rapidly and precisely inflating the balloon lying across the orifice were able to disrupt the stricture and relieve the stenosis. Results matched those of early non-visual operations. Recently the cardiologist has expanded the approach to relieve other constricted orifices in the heart and great vessels and to close abnormal openings. In isolated pulmonary stenosis, the nearly complete relief of obstruction and the tolerance of the circulation to blunt disruption of valvular stenosis bodies well for the long-term success of balloon valvuloplasty in this congenital malformation of the heart.     

New Concept in Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA)

The world-wide impact of traumatic injury and associated hemorrhage on human health and well-being is significant. Methods to manage bleeding from sites within the torso, referred to as non-compressible torso hemorrhage (NCTH), remain largely limited to the use of conventional operative techniques. The overall mortality rate of patients with NCTH is approximately 50%. Studies from the wars in Afghanistan and Iraq have suggested that up to 80% of potentially survivable patients die as a result of uncontrolled exsanguinating hemorrhage. The commercially available resuscitative endovascular balloon occlusion of the aorta (REBOA) is a percutaneous device for the rapid control of torso hemorrhage in trauma. A compliant balloon is inserted via the femoral artery and inflated in the thoracic or abdominal aorta, providing inflow control of the abdomen, pelvis, or groin/lower extremities. Recent studies indicate that REBOA carries an inherent risk of aortic injury due to over-inflation and possible risk of aortic or iliac artery rupture. A new approach isto resolve the issue of balloon sizing and over-inflation. We propose a novel concept to be used in trauma facility for arterial occlusion to eliminate arterial injury and the risk of vascular rupture through real time balloon diameter profile measurements to ensure proper inflation. The proposed concept, called Smart Resuscitative Endovascular Balloon Occlusion (SREBO) will be novel in the following aspects: 1) It will have electrical conductance-based navigation technology to target the desired site of balloon deployment in the aorta, 2) The balloon can determine the time of proper inflation using electrical conductance catheter technology. This technology would eliminate the risk of arterial rupture and simplify the procedure in the trauma facility or medical clinics without significant training. The results can be displayed on a handheld device. This novel device has the potential to save civilians in trauma or soldiers injured on the battlefield.     

The effect of locally delivered c-myc antisense oligonucleotides combined with intravascular brachytherapy of 188Re liquid-filled balloon therapy on vascular smooth muscle cell proliferation in rabbit iliac arteries after injury with a balloon catheter.

Poststenting restenosis is a significant clinical problem that involves vascular smooth muscle cell (VSMC) proliferation. We primarily investigated the effect of c-myc antisense oligodeoxynucleotides (ASODNs) combined with 188Re radiation therapy on VSMC proliferation in rabbit common iliac arteries injured by the porous balloon catheter to explore the therapeutic potential of the combined therapy for the prevention of restenosis. The iliac arteries in rabbits were injured with balloon catheters, and radiation therapy was carried out with a 2.5 mm balloon catheter filled with 188Re (8 or 15 Gy), and ASODNs (300 microg) were applied to the adventitia introduced using a pluronic gel releasing system and a lipofectin delivery system. After 3 weeks, the animals were killed and defined segments of arteries were sectioned. The histological sections were stained using alpha-actin immunohistochemistry staining. The positive alpha-actin ratios were calculated and analyzed statistically among groups. In contrast to the rate of alpha-actin positive cell staining in the control group, the rate of alpha-actin positive cell staining did not decrease (P > 0.05) in the 188Re-irradiated group (8 Gy). However, in the ASODN-treated group, the 188Re-irradiated group (15 Gy), and the combined ASODN - 188Reirradiated groups (8 or 15 Gy), the ratios had markedly decreased (P < 0.01). The effect of the combined group (ASODNs + 188Re (15 Gy)) provided the lowest level of alpha-actin positive cell staining (P < 0.01). The ASODNs (300 microg) effectively decreased VSMC poliferation. The effect of the 188Re radiation on the VSMCs depended on the dosage. The ASODNs (300 microg) and combined 188Re irradiation effectively lowered VSMC proliferation, and the effect was better than that achieved with any other treatment.     

New methods of making blocked coronary arteries patent again.

The use of percutaneous transluminal coronary angioplasty is limited by procedural complications and the serious drawback of restenosis, but some new techniques have been developed in an attempt to lower the complication rate for difficult lesions and reduce the rate of restenosis. These include devices to physically remove atheromatous plaque, such as the Simpson Coronary AtheroCath and the transluminal extraction catheter, as well as devices to ablate the plaque in situ, including the Rotablator and the excimer laser catheter. Although each device may have advantages in certain types of lesion, few data on their use have been reported in properly controlled randomised trials. The data available so far do not suggest that these devices will be safer than balloon angioplasty or that they will reduce restenosis. However, using metallic stents to support coronary arteries after balloon angioplasty seems to reduce acute complications and to lower the rate of restenosis, and the use of stents is likely to increase.     

局麻药连续伤口输注技术在临床术后镇痛中应用的研究进展

局麻药连续伤口输注技术是区域阻滞的一种,其从源头上阻滞了切口伤害性刺激信号的发生与传导。作为新一代的术后镇痛方式,它通过一种与神经周围或切口中插管相连的弹力球囊或便携式电子泵实施患者自我控制式区域镇痛。与传统的术后镇痛方式相比,它可安全有效便捷的用于临床术后镇痛,又可避免硬膜外穿刺置管的风险,还能减少阿片类药物的应用,因而在安全镇痛和加速康复方面更有优势。本文就局麻药连续伤口输注技术的应用作以下综述,为临床术后多模式镇痛提供参考。