Improved hydrodynamics of a new aortic cannula with a novel tip design

BACKGROUND: Reduction of atheroembolic complications during cardiopulmonary bypass remains a major challenge in cardiac surgery. New cannula tip designs may help to attenuate this problem by improved hydrodynamics. METHODS: Pressure gradients and back pressures of a new aortic cannula tip design were measured and compared with the Medos X-Flow, Sarns Soft-Flow and Argyle THI cannulae at various flow rates in a mock circulation followed by flow visualization. RESULTS: Pressure gradients were the lowest for the new cannula. Back pressures of the new cannula were up to 84% lower than for the Argyle cannula. The back pressure profile and flow visualization of the new cannula showed broad centric flow dispersion with a transcannula increase of flow area from 38 mm2 to 139 mm2. CONCLUSIONS: The new design of an aortic cannula tip provides improved hydrodynamics, with low pressure gradients, low back pressures and a uniform central dispersion of flow, reducing the sandblasting effect.     

Brain microembolic counts during extracorporeal circulation depend on aortic cannula position

Thrombofibrinous and gaseous brain microemboli are commonly observed during extracorporeal circulation in patients undergoing cardiac surgery. Recent studies showed a preference of microemboli to the left hemisphere. We hypothesized that placement of the aortic cannula tip within the aorta descendens rather than in the aorta ascendens as commonly used reduces the number of microemboli to the brain and also reduces the side preference. Of 60 patients undergoing elective coronary artery bypass grafting primarily randomized to either a short aortic cannula (aorta ascendens) or an elongated one (aorta descendens), 29 (16 and 13) patients had complete and technically perfect continuous intraoperative transcranial Doppler sonography with embolus detection bilaterally. The number of high-intensity transient signals (HITS) was 994 +/- 2118 (mean +/- SD) for the short cannula group and was significantly lower with the elongated cannula (223 +/- 208; p < 0.02). HITS counts per min also differed significantly in favour of the aorta descendens group (p < 0.02), but there was an overlap. Thus, elongated cannulas can reduce, but not prevent microembolism to the brain. The side-to-side ratio of microemboli revealed more events in the left hemisphere, but this was similar in both groups. This suggests that individual anatomic factors may be responsible for this hemodynamically-mediated effect.     

An in vitro evaluation of a new cannula tip design compared with two clinically established cannula-tip designs regarding aortic arch vessel perfusion characteristics

We investigated in vitro aortic arch vessel perfusion characteristics of single and multiple jet-stream cannulae and a new dispersion stream tip aortic cannula. Pressures and flows of all arch vessels were measured while directing cannulae jets at the different arch vessels using 6 l/min pump flow. The highest increase in pressure above the set systemic level of 80 mmHg and increase in flow above the set normal flow distribution in the arch vessels occurred in the jet-streamed arch vessels with the single stream cannula. The values were as follows: 29 mmHg and 118 ml/min for the innominate artery, 28 mmHg and 42 ml/min for the left common carotid artery, and 25 mmHg and 54 ml/min for the left subclavian artery. The dispersion stream cannula showed increases in pressure and flow, followed by the multiple stream cannula. Aortic cannula tips and the orientation of jets are potential sources of imbalances of arch vessel perfusion with possible clinical implications regarding perfusion of arch vessels during extracorporeal circulation.     

Humidified high-flow nasal cannula: is it the new and improved CPAP?

Humidified high-flow nasal cannula (HHFNC) therapy for neonates has become increasingly popular in recent years. It is frequently used in circumstances when continuous positive airway pressure (CPAP) might otherwise have been used.Limited evidence is available to support the specific role, efficacy, and safety of HHFNC in newborns. This evidence suggests that HHFNC provides inconsistent and relatively unpredictable positive airway pressure, but may be effective in the treatment of some neonatal respiratory conditions while being more user-friendly for caregivers than conventional CPAP. Concerns regarding infection risks have resulted in one major HHFNC device being withdrawn from the market before being recently reintroduced.Caution should be exercised in the use of HHFNC in neonates (eg, by limiting its use to relatively lower flows and to relatively larger neonates, while collecting and closely monitoring safety and efficacy data) until further evidence is available to clearly delineate its role, as well as to support its safety and efficacy.     

In vitro hydrodynamics of the Embol-X cannula

BACKGROUND: Prevention of intraoperative plaque dislodgement in patients with atherosclerotic ascending aorta by development of innovative aortic cannula designs gains growing interest in cardiac surgery. To increase knowledge about the hydrodynamics of the innovative Embol-X cannula, which includes an intra-aortic filter device targeting at atheromatous emboli capture, was the aim of the present study. METHODS: Pressure gradients and back pressures of the Embol-X cannula were measured at varying flow rates in a mock circulation and compared with two commonly used single-stream cannulae. RESULTS: At a flow rate of 5.5 l/min, pressure gradients across the Argyle and the RMI cannulae were 48% and 62% and back pressures 25% and 47% lower than the corresponding values across the Embol-X cannula. CONCLUSIONS: The novel concept of integrating a filter device may provide clinical advantages concerning neurologic outcome. Further in vivo studies seem to be desirable to obtain more information concerning the clinical effects of the Embol-X cannula hydrodynamics.     

Confirmation of intraosseous cannula placement based on pressure measured at the cannula during squeezing the extremity in a piglet model

Aim of the study

We sought to assess the reliability of the method using the pressure measured at the intraosseous (IO) cannula while squeezing the involved limb (P_squeezing) in determining the position of the IO needle and to compare its performance with that of the traditional confirmation method.

Methods

Eighty limbs of twenty domestic swine were assigned to one of three conditions regarding the position of the IO needle; correct placement (n = 40), incorrect placement in which the IO needle was placed into the subcutaneous space without entering the bone (incorrect-subcutaneous placement, n = 20), or incorrect placement in which the IO needle passed entirely through the bone (incorrect-penetrating placement, n = 20). A blinded investigator randomly identified the position of the needle by the traditional method or test method using P_squeezing. If P_squeezing was 80 mmHg or higher, the IO cannula was regarded as incorrectly placed.

Results

P_squeezing was higher in incorrect placements (176.0 mmHg (130.0–195.0)) compared with that in correct placements (27.0 mmHg (20.0–34.0)) (p < 0.001). The test method correctly identified all 40 placements, but the traditional method was incorrect for one (5%) of 20 correct placements (p = 1.000) and 7 (35%) of 20 incorrect placements (p = 0.008). In incorrect placements, false positive results occurred mainly in incorrect-penetrating placements.

Conclusion

We suggest that the method using the pressure measured at the IO cannula can be used when there is uncertainty about the position of the IO cannula after determination using traditional methods.     

经口气管插管的固定方法

机械通气技术是急救中不可缺少的手段,经口气管插管是危重患者进行心肺复苏,抢救呼吸衰竭、呼吸道梗阻等危急重症患者最常用的方法。因此,气管插管固定的牢固程度直接影响呼吸机的治疗效果。2010年以来,本科室采用多功能口咽通气道固定气管插管,取得了满意效果,现报道如下。1材料与方法1.1材料     

Insertion of percutaneous ECMO cannula

Extracorporeal membrane oxygenation plays a very important role in resuscitation when patients are approaching impending death, because it can provide adequate cardiac and pulmonary support immediately. But percutaneous tunnel creation is a critical step for set-up of extracorporeal membrane oxygenation by percutaneous Seldinger technique. A guidewire dilator forceps used in percutaneous tracheostomy was tried to create the femoral subcutaneous tunnel. We found it could make easy the advancement of the percutaneous cannula into the vessels and over-dilatation of the vessels could also be prevented by controlled jaw opening.     

Revival of an old method with new techniques: balloon aortic valvuloplasty of the calcified aortic stenosis in the elderly

Balloon aortic valvuloplasty (BAV), introduced since almost 20 years, has experienced a revival for its use in the treatment of elderly patients with severe calcified aortic stenosis that are associated with high operative risk and co-morbidities. This is due to the introduction of new balloon catheters and techniques. This study reports about 75 such cases performed within the past 28 months. The mean age of our patient group was 78 +/- 7 years (median = 80 years). Risk calculation with the EuroSCORE demonstrated an average value of 24.4 +/- 19.5%. BAV was performed along with burst pacing to reduce transvalvular blood flow for stabilization of the balloon catheter until blood pressure dropped to less than 50 mmHg. BAV was performed in 72 patients with a procedural success rate of 73%. There was a decrease of 31 mmHg peak-to-peak gradient across the aortic valve from 63 +/- 35 to 32 +/- 22 mmHg (P < 0.0001). Mean gradient was reduced from 51 +/- 24 to 27 +/- 15 mmHg (P < 0.0001). Aortic valve area increased by 49% from 0.84 +/- 0.33 to 1.25 +/- 0.45 cm(2) (P < 0.0001). Serious adverse events (SAE) occurred in 17% of the 75 BAV procedures. Follow-up revealed a significant improvement in 6-month and 1-year survival. The improved technology of BAV makes this technique attractive for elderly patients who are at high operative risk or in cases where valve replacement was refused for any reason.     

新型气管插管气道湿化35例临床研究

目的:探讨气管插管气道湿化的有效方法。方法:将70例慢性阻塞性肺疾病(COPD)急性发作致呼吸衰竭采用机械通气辅助呼吸者随机分为实验组和对照组各35例,实验组使用新型气管插管进行气道湿化,在湿化管外口接静脉输液装置一套,根据病情每天持续滴入生理盐水250 ml左右;对照组使用传统式气管插管进行气道湿化,总量为每天250 ml左右。观察两组治疗前和治疗结束时血气分析,抗生素应用时间,住院时间和住院费用及病死率。结果:两组在治疗结束时pH、PaCO2、PaO2与治疗前比较均有明显改善,差异有显著性(P<0.05),实验组抗生素应用时间和住院时间、住院费用与对照组相比明显减少,且病死率降低,差异有显著性(P<0.05)。结论:新型气管插管气道湿化操作简单、方便,效果更可靠。     

Care of peripheral venous cannula sites

Peripheral venous catheters are commonly used in hospitals to deliver intravenous therapy. They are associated with a range of complications that can be damaging to patients' health and increase healthcare costs. In order to minimise the risk of these complications, thorough patient assessment and careful catheter management are essential.     

一次性药物气管垫的制作与临床应用研究

目的 研制一种能保持气管切开切口皮肤干燥,且能有效预防和治疗气管切开切口感染的药物垫.方法 根据3L带孔粘贴敷料的制作方法和特点,设计制作成由高级软纸、无纺布、脱脂棉层、药层组成的一次性药物气管垫并应用于临床.选择行气管切开且神志清醒的患者72例,随机分为观察组和对照组各36例.观察组使用一次性药物气管垫换药,对照组使用自行剪裁无菌纱布块换药.于气管切开后第3、6、10天做气管切口局部细菌培养,并观察气管切口局部感染情况及患者的满意度.结果 通过观察组和对照组的细菌培养,观察组阳性率明显低于对照组;气管切口局部感染率观察组也明显低于对照组;患者的满意度观察组明显高于对照组,经统计处理,差异有统计学意义(P<0.01).结论 采用一次性药物气管垫保护气管切口,操作省时省力,不仅能保持切口周围皮肤清洁干燥,改善患者的舒适度,而且能有效预防和治疗气管切开切口的感染,显著降低感染的发生,从而促进患者顺利康复,减少住院时间和患者的费用.值得临床推广应用.     

A new cannula with a flexible tip (Swing Tip) may improve the success rate of endoscopic retrograde cholangiopancreatography

BACKGROUND AND STUDY AIMS: Endoscopic retrograde cholangiopancreatography (ERCP) is sometimes unsuccessful because the anatomy of the papilla of Vater precludes cannulation by routine means. The efficacy of a new flexible tip cannula (the Swing Tip) was studied in patients in whom routine ERCP was unsuccessful. PATIENTS AND METHODS: The Swing Tip cholangiographic catheter has an articulation at its tip which allows the tip to be flexed from 90 degrees to 30 degrees. Routine cholangiography was successful in 175 of 195 patients in whom it was attempted between September 2000 and November 2001. ERCP with the Swing Tip catheter was attempted in the 20 patients in whom ERCP had failed. RESULTS: In 17 of 20 patients, we attempted to insert the Swing Tip catheter into the common bile duct to perform cholangiography. Insertion was successful in 11 patients and unsuccessful in six. There were no complications related to the procedure. CONCLUSION: The Swing Tip catheter is a useful adjunct to standard ERCP catheters for patient in whom standard techniques are unsuccessful.