Cannula Diameter Research Articles

The Importance of Planning Ahead: A Three-Dimensional Analysis of the Novel Trans-Facet Corridor for Posterior Lumbar Interbody Fusion Using Segmentation Technology

The rise of minimally invasive lumbar fusions and advanced imaging technologies has facilitated the introduction of novel surgical techniques with the trans-facet approach being one of the newest additions. We aimed to quantify any pathology-driven anatomic changes to the trans-facet corridor, which could thereby alter the ideal laterality of approach to the disc space. In this retrospective cohort study, we measured the areas and maximum permissible cannula diameters of the trans-facet corridor using commercially available software (BrainLab, Munich, Germany). Exiting and traversing nerve roots, thecal sacs, and lumbar vertebrae were manually segmented on T2-SPACE magnetic resonance imaging. Spondylolisthesis, disc protrusions, and disc space heights were recorded. A total of 118 trans-facet corridors were segmented bilaterally in 16 patients (65.6 ± 12.1 years, 43.8% female, BMI 29.2 ± 5.1 kg/m2). The mean areas at L1-L2, L2-L3, L3-L4, and L4-L5 were 89.4 ± 24.9 mm2, 124 ± 39.4 mm2, 123 ± 26.6 mm2, and 159 ± 42.7 mm2, respectively. The mean permissible cannula diameter at the same levels were 7.85 ± 1.43 mm, 8.98 ± 1.72 mm, 8.93 ± 1.26 mm, and 10.2 ± 1.94 mm, respectively. Both parameters increased caudally. Higher degrees for spondylolisthesis were associated with larger areas and maximum cannula diameters on regression analysis (p < 0.001). Our results illustrate that pathology, like spondylolisthesis, can increase the area of the trans-facet corridor. By understanding this effect, surgeons can better decide on the optimal approach to the disc while taking into consideration a patient's unique anatomy.

Consideration of the diameter of superficial temporal arteries related to filler injections in the temporal region.

The concavity of the temple due to adipose tissue atrophy from aging accentuates the zygomatic arch and lateral orbital rim, leading to an aged appearance. The use of hyaluronic acid filler in the temporal region has gained popularity due to its procedural simplicity and consistent outcomes. To evaluate the safety of administering hyaluronic acid filler in the temporal region concerning the frontal branch of the superficial temporal artery, which is at risk of injury. Empirical observations were conducted on the internal diameter of the frontal branch of the superficial temporal artery, a critical anatomical site for potential injury. A significant proportion of the artery segments exhibited an internal diameter below 1 mm. Given that the outer diameter of an 18-gauge cannula is 1.27 mm, this method can be considered a relatively secure approach for enhancing the temporal region. The use of an 18-gauge cannula for hyaluronic acid filler administration in the temporal region appears to be a safe and effective method, with the potential risk to the frontal branch of the superficial temporal artery being minimal.

Impact of cannula diameter on pregnancy outcomes after minimally invasive fetal laser surgery in the treatment of twin-to-twin transfusion syndrome: A systematic review and meta-analysis.

Preterm prelabor rupture of membranes (PPROM) remains a major complication of fetal laser surgery in the treatment of twin-to-twin transfusion syndrome (TTTS). The aim of the study was to determine the impact of cannula size on pregnancy outcomes, with a particular focus on PPROM. The protocol was developed and registered in the PROSPERO database under registration number CRD42022333630. The PubMed, Web of Science, and EMBASE databases were searched electronically on May 18, 2022, and updated on March 2, 2023, utilizing a combination of the relevant MeSH terms, keywords, and word variants for "TTTS" and "laser". Randomized controlled trials, prospective and retrospective cohorts, case-control studies, and case reports/series with more than five participants were considered eligible for inclusion. Studies reporting the cannula diameter and PPROM rate after laser surgery in the treatment of monochorionic pregnancies affected by TTTS between 16- and 26 weeks' gestation were included. Data was extracted independently, and when appropriate, a random-effects meta-analysis was undertaken to calculate pooled estimates and their confidence intervals. Heterogeneity in the effect estimates of the individual studies was calculated using the I2 statistic. The primary outcome was PPROM rate. Secondary outcomes were survival rate, preterm birth, and incomplete surgery. The quality of the included studies was assessed using a modified quality in prognosis study tool. We included a total of 22 studies, consisting of 3426 patients. Only one study was scored as low quality, seven as moderate quality, and the remaining 14 as high quality. The mean PPROM rate after laser surgery treating TTTS was 22.9%, ranging from 11.6% for 9 French (Fr) to 54.0% for 12 Fr. Subsequent meta-regression for the clinically relevant PPROM rate before 34 weeks of gestation, showed increased PPROM rates for increased cannula size (p-value 0.01). This systematic review confirmed PPROM as a frequent complication of fetal laser surgery, with a mean PPROM rate of 22.9%. A larger cannula diameter relates to a significant higher PPROM risk for PPROM before 34 weeks gestation. Hence, the ideal balance between optimal visualization requiring larger port diameters and shorter operation time and more complete procedures that benefit from larger diameters is crucial to reduce iatrogenic PPROM rates.

Laparoscopic Trocars: Marketed Versus True Dimensions–A Descriptive Study

Study ObjectiveTo establish true dimensions of single-use laparoscopic trocars as compared to marketed dimensions, calculate corresponding incision sizes, examine what trocar size categories are based on, and outline accessibility of information regarding true dimensions. DesignDescriptive study SettingLaparoscopic disposable trocars available in North America and Europe are marketed in several distinct categories. In practice, trocars in the same size category exhibit different functionality (ability to introduce instruments/needles and retrieve specimens) and warrant different incision lengths. PatientsN/A InterventionsN/A Measurements and Main ResultsTrue dimensions for 125 trocars (bladeless, optical, and balloon) were obtained from 9 vendors covering 8 marketed size categories (3, 3.5, 5, 8, 10, 11, 12, and 15-mm trocars). On average, true inner cannula diameter was 0.92 mm wider (standard deviation [SD] 0.41 mm, range 0 – 2.4 mm) than the marketed size category, with the widest range in the 5-mm category. For 5-mm trocars, mean true inner diameter was 6.1 mm (SD 0.45, range 5.5 – 7.4) and true outer diameter 8.3 mm (SD 0.71, range 8.0 – 10.7). For 12-mm trocars, mean true inner diameter was 13.0 mm (SD 0.21, range 12 – 13.3) and outer diameter 15.3 mm (SD 0.48, range 14.4 – 16.8). Five-mm trocars necessitate a mean incision size of 13.0 mm (SD 1.1, range 12.1 – 16.8) and 12-mm trocars a mean incision of 24.0 mm (SD 0.75, range 22.6 – 26.4). No vendors stated actual diameters on company website or catalogue. In one instance the Instructions For Use document contained the true inner diameter. ConclusionTrocar size categories give a false sense of standardization when in actuality there are considerable within-category differences in both inner and outer diameters, corresponding to differences in functionality and required incision sizes. There is no universally applied definition for trocar size categories. Accessibility of information on true dimensions is limited.

Using Novel Segmentation Technology to Define Safe Corridors for Minimally Invasive Posterior Lumbar Interbody Fusion.

There has been a rise in minimally invasive methods to access the intervertebral disk space posteriorly given their decreased tissue destruction, lower blood loss, and earlier return to work. Two such options include the percutaneous lumbar interbody fusion through the Kambin triangle and the endoscopic transfacet approach. However, without accurate preoperative visualization, these approaches carry risks of damaging surrounding structures, especially the nerve roots. Using novel segmentation technology, our goal was to analyze the anatomic borders and relative sizes of the safe triangle, trans-Kambin, and the transfacet corridors to assist surgeons in planning a safe approach and determining cannula diameters. The areas of the safe triangle, Kambin, and transfacet corridors were measured using commercially available software (BrainLab, Munich, Germany). For each approach, the exiting nerve root, traversing nerve roots, theca, disk, and vertebrae were manually segmented on 3-dimensional T2-SPACE magnetic resonance imaging using a region-growing algorithm. The triangles' borders were delineated ensuring no overlap between the area and the nerves. A total of 11 patients (65.4 ± 12.5 years, 33.3% female) were retrospectively reviewed. The Kambin, safe, and transfacet corridors were measured bilaterally at the operative level. The mean area (124.1 ± 19.7 mm2 vs 83.0 ± 11.7 mm2 vs 49.5 ± 11.4 mm2) and maximum permissible cannula diameter (9.9 ± 0.7 mm vs 6.8 ± 0.5 mm vs 6.05 ± 0.7 mm) for the transfacet triangles were significantly larger than Kambin and the traditional safe triangles, respectively (P < .001). We identified, in 3-dimensional, the borders for the transfacet corridor: the traversing nerve root extending inferiorly until the caudal pedicle, the theca medially, and the exiting nerve root superiorly. These results illustrate the utility of preoperatively segmenting anatomic landmarks, specifically the nerve roots, to help guide decision-making when selecting the optimal operative approach.

A Multivariate Meta-Analysis for Optimizing Cell Counts When Using the Mechanical Processing of Lipoaspirate for Regenerative Applications.

A comprehensive literature search was focused on the mechanical processing of lipoaspirate, without the use of enzymes. Data from the articles were integrated by utilizing a multivariate meta-analysis approach and used to create a statistical-based predictive model for a combination of multiple variables. Starting with 10,000 titles, 159 articles were reviewed, and 6 met the criteria for inclusion and exclusion. The six studies included data on 117 patients. Sixteen factors were analyzed and six were identified as significant. The predictive profilers indicated that the optimal combination to maximize the cell yield was: a centrifuge force of 2000× g, a centrifuge time of 10 min, a cannula diameter of 2 mm, and an intra-syringe number of passes of 30. The optimal patient factors were a higher BMI and younger age. The novelty of the method used here was in combining data across different studies to understand the effect of the individual factors and in the optimization of their combination for mechanical lipoaspirate processing.

Factors influencing nasal airway pressure and comfort in high-flow nasal cannula oxygen therapy: a volunteer study

BackgroundHigh-flow nasal cannula (HFNC) oxygen therapy is essentially a constant-flow, noninvasive respiratory support system similar to a noninvasive ventilator operating in constant-flow mode. The clinical outcome of HFNC oxygen therapy is strongly associated with the pressure generated by high-flow gas and the patient’s comfort level. This study was performed to explore the relevant factors affecting pressure and comfort of HFNC oxygen therapy in vivo.MethodsThirty-five healthy volunteers were enrolled in the trial. They underwent placement of nasal cannulas of various inner diameters (3, 4 or 5 mm) and treatment with different HFNC devices [HFT-300 (Weishengkang Medical Technology Co., Ltd., Jiangsu China) or H-80 M (BMC Medical Co., Ltd., Beijing China)],and the nasal airway pressure and comfort were assessed. Multiple linear regression was used to determine predictors of airway pressure.ResultsMultiple linear regression showed that the end-expiratory pressure was associated with the flow rate, sex, height, and cannula size. The end-expiratory pressure increased by 0.6 cmH2O per 1-mm increase in cannula diameter, decreased by 0.3 cmH2O per 10-cm increase in participant height (with a 0.35 cmH2O decrease for men), and increased by 1 cmH2O when the flow rate increased by 10 L/min (R2 = 0.75, P < 0.05 for all variables in model). In addition, the pressure generated by the H-80 M device was higher than that generated by the HFT-300 device (P < 0.05). Discomfort manifested as difficulty in expiration, and its severity increased as the cannula diameter increased; however there was no significant difference in comfort between the two HFNC devices (P > 0.05).ConclusionIn volunteers undergoing HFNC oxygen therapy, the nasal cannula diameter, flow rate, sex, height, and device model can affect the nasal airway pressure, and the nasal catheter diameter and flow rate can affect comfort. These factors should be given close attention in clinical practice.Trial registrationChiCTR2300068313 (date of first registration: 14 February 2023, https://www.chictr.org.cn).

Preventing Acute Limb Ischemia during VA-ECMO-In Silico Analysis of Physical Parameters Associated with Lower Limb Perfusion.

Peripheral femoro-femoral veno-arterial extracorporeal membrane oxygenation is increasingly used in refractory cardiogenic shock. However, the obstruction of the femoral artery by the return cannula could lead to acute limb ischemia, a frequently encountered situation that is inconstantly prevented by the adjunction of a distal perfusion cannula (DPC). The aim of this study was to investigate the influence of three physical parameters on the perfusion of the cannulated lower limb. Using patient-specific arterial models and computational fluid dynamic simulations, we studied four diameters of arterial cannula, three diameters of DPC, and two percentages of arterial section limitation. We found that adequate perfusion of the cannulated limb was achieved in only two out of the twenty-one configurations tested, specifically, when the arterial cannula had a diameter of 17 Fr, was considered to limit the section of the artery by 90%, and was associated with an 8 Fr or a 10 Fr DPC. Multivariable analysis revealed that the perfusion of the cannulated lower limb was correlated with the diameter of the DPC, but also with the diameter of the arterial cannula and the percentage of arterial section limitation. In most of the cases simulated here, the current system combining unsized arterial cannula and non-specific DPC was not sufficient to provide adequate perfusion of the cannulated lower limb, urging the need for innovative strategies to efficiently prevent acute limb ischemia during peripheral femoro-femoral veno-arterial extracorporeal membrane oxygenation.

Determination of Appropriate Artery Cannula Diameter by Measuring Radial Artery Diameters Using Ultrasonography and Investigation of the Correlation of “Allen Test” with Doppler Ultrasonography

Determination of Appropriate Artery Cannula Diameter by Measuring Radial Artery Diameters Using Ultrasonography and Investigation of the Correlation of “Allen Test” with Doppler Ultrasonography

Smaller Return Cannula in Venoarterial Extracorporeal Membrane Oxygenation Does Not Increase Hemolysis: A Single-Center, Cohort Study.

The aim of this study was to explore the association between arterial return cannula diameter and hemolysis during peripheral VA ECMO. We identified 158 adult patients who received peripheral VA ECMO at our institution from the national ECMO database (EXCEL) between January 2019 and July 2021. We classified patients into a small cannula group (15 Fr diameter, n = 45) and a large cannula group (≥17 Fr diameter, n = 113), comparing incidences of clinical hemolysis and plasma free hemoglobin (pfHb). Moderate hemolysis is defined as having pfHb 0.05-0.10 g/L and severe hemolysis as having pfHb >0.10 g/L sustained for at least two consecutive readings or leading to a circuit change. There were no significant differences in rates of moderate hemolysis between small and large cannula groups (1 vs. 6; p = 0.39) and severe hemolysis (0 vs. 3; p = 0.27), nor was the pfHb level significantly different at 4 hours (0.086 ± 0.096 vs. 0.112 ± 0.145 g/L; p = 0.58) and at 24 hours (0.042 ± 0.033 vs. 0.051 ± 0.069 g/L; p = 0.99). There were no increased rates of hemolysis when comparing small versus large arterial return cannula diameter in peripheral VA ECMO.

Experimental study on clinical and morphological determination of the optimal cannula diameter for lipoaspirate harvest from rabbit inguinal fat pad.

Determining the most appropriate cannula diameter for lipoaspirate harvesting is important, both in terms of the quality and composition of the material obtained, and the ease of practical use of the cannula. The size of the cannula is one of the main factors affecting the qualitative characteristics of the obtained lipoaspirate sample for further use of adipose tissue. The purpose of the investigation was to clinically and histomorphometrically determine the optimal cannula diameter for lipoaspirate samples collection from rabbit inguinal fat pad in an experimental study. The methods of Animal models, Surgical procedures, Macroscopic examination, Histological examination, and Morphometric study were applied. There is a direct correlation between the percentage of connective tissue fibres in the lipoaspirate and the diameter of the cannula. The lack of clear criteria for selecting a lipoaspiration cannula is one of the limitations to obtaining generally accepted lipoaspiration protocols with subsequent use of adipose tissue. In this study, the animal experiment determined the most ideal cannula diameter suitable for collecting the largest amount of lipoaspirate for subsequent use.

Preoperative computed tomography in the planning of median resternotomy in children

The capabilities of computed tomography (CT) in the diagnosis of mediastinal adhesions and measuring the density of adhesions when planning midline resternotomy in children were assessed, and the effect of preoperative CT on the incidence of surgical complications was studied. According to several authors, the frequency of resternotomies in cardiac surgery is up to 20% of the total number of surgeries per year and is accompanied by significant difficulties in the isolation of the heart and vessels. In pediatric cardiac surgery, complex congenital heart disease (CHD) mostly requires a staged approach. The staging of complex CHD correction and the need for repeated surgeries in most cardiac defects make the problem of safe repeated surgical access urgent. Postoperative adhesions are one of the most acute problems in modern cardiac surgery. The formation of adhesions is an inevitable reaction of the body after primary cardiac surgery. Massive adhesions that develop after surgery most commonly lead to adhesion of the heart and major great vessels to the posterior surface of the sternum. These changes are especially pronounced in children due to the high reactivity of the body and the lack of technical possibility and expediency of pericardial suturing after surgery. Rough adhesions during resternotomy complicate the cardiac surgeons task and increase the risk of complications. The main dangers are damage to various structures in the thorax such as the right and left heart, aorta, coronary arteries, pulmonary artery, and brachiocephalic vein. The diagnosis of postoperative adhesions in the mediastinum before resternotomy is difficult. CT has the widest diagnostic capabilities for assessing mediastinal adhesions. When performing CT as a part of preoperative resternotomy planning, it is important to examine the mediastinal topography, assess the degree of adjacency of the pericardium and mediastinal structures, determine the presence and density of adhesions, and assess patency and diameter of great vessels to select cannulas and cannulation methods necessary for emergency start of cardiopulmonary bypass (CPB) in cardiac trauma. These criteria are important when planning midline resternotomy to reduce the risks of traumatization of cardiac structures and great vessels and allow correction of surgical tactics and timely preventive surgical measures. Depending on the density, extent, and localization of adhesions, the cardiolysis technique and cannulation of great vessels required for initiation of emergency CPB may be changed. The use of preoperative CT when planning midline resternotomy in children allows to predict the risks of damage of cardiac structures and great vessels and visualize adhesive bands and measure their density, which helps the surgeon to adjust surgical tactics regarding the method and volume of cardiolysis and assess patency and diameter of great arteries and veins, thus determining the cannulation method and cannula diameter in advance if urgent CPB is needed. Therefore, standardization of CT description protocols for midline resternotomy planning with assessment of key criteria is an urgent task and requires further development.

Are large diameter cannulas safe in nonsurgical rhinoplasty?

Are large diameter cannulas safe in nonsurgical rhinoplasty?

Dimensions of bony Kambin's triangle pertaining to endoscopic procedure

BackgroundEndoscopic procedures nowadays are successful, minimally invasive, and safer, with fewer intraoperative and postoperative complications and shorter hospital stays. Kambin's triangle (KT) is the three-dimensional configuration that is used as a transforaminal anatomical corridor for epidural steroid injections and endoscopic surgeries for various lumbar pathologies. This study aims to estimate the dimensions of KT and diameter of the cannula for the transforaminal surgical approaches using KT in the Chhattisgarh population. MethodsSeven human cadavers (three males and four females) were included in the study for observing KT. Dissection was done to carefully clear landmarks, including the vertebral bodies, intervertebral disc, exiting nerve root, and superior articular process. Base (a horizontal plane passing through the superior border of the caudal vertebra) and height (along the superior articular process of the inferior vertebra in line with the articular facet) were measured. Hypotenuse, semiperimeter of the triangle, area of triangle, diameter, and area of the inscribed circle were calculated. ResultsHeight, base, and inscribed circle diameter increased from L1-L2 to L4-L5 then decreased to L5-S1. There was no statistically significant difference between males and females. The safest admissible cannula diameter according to the current study that can be used at all levels in KT was 6.06 mm. ConclusionThis study provides the safest cannula size to be considered in the patients of the Chhattisgarh population during transforaminal approaches in the lumbar area. Minimally invasive surgery and shorter hospitalization are vital criteria to evaluate any surgery these days.

Improving adult pulsatile minimal invasive extracorporeal circulation in a mock circulation.

Pulsatile extracorporeal circulation (ECC) may improve perfusion of critical organs during cardiac surgery. This study analyzed the influence of the components of a minimal invasive ECC (MiECC) on the transfer of pulsatile energy into the pseudo-patient of a mock circulation. An aortic model with human-like geometry and compliance was perfused by a diagonal pump. Surplus hemodynamic energy (SHE) was determined from flow and pressure data. Five adult-size oxygenator models and three sizes of cannulas were compared. Pulsatile pump settings were optimized, and parallel dual-pump configurations were evaluated. Oxygenator models showed up to twofold differences in pressure gradients and influenced SHE at flow rates up to 2.0L min-1 . Adjustments of frequency, systole duration, and rotational speed gain significantly improved SHE compared with empirical settings, with SHE above 21% of mean arterial pressure at flow rates of 1.0L min-1 to 1.5L min-1 and SHE above 5% at 3.5L min-1 . Small diameter cannula (15 Fr) limited SHE compared with larger cannula (21 Fr and 23 Fr). Two diagonal pumps did not provide higher SHE than a single pump, but permitted additional control over pulse pressure and SHE by varying the total fraction of pulsatile flow and the fraction of flow bypassing the oxygenator. Proper selection of components and optimizations of pump settings significantly improved pulse pressure and SHE of pulsatile MiECC. Surplus hemodynamic energy depended on flow rate with a maximum at 1.0L min-1 -1.5L min-1 . Pulsatile MiECC may specifically assist organ perfusion during phases of low flow.

Compatibility of PiC Insupen Needles with a Broad Range of Pens for the Injection of Subcutaneously Administered Drugs for Diabetes.

PurposeTo test the compatibility of PiC Insupen needles with a broad range of pens produced by different manufacturers for the injection of subcutaneously administered drugs.Patients and MethodsThe “extreme” products in PiC pen needles range were considered (G33x4 mm and G29x12 mm), to verify that the compatibility was not affected by the cannula diameter and length. Following the launch of the G34x3.5mm needle, additional tests were performed comparing G33x4 and G34x3.5 pen needles. A test medium with viscosity similar to insulin was used. Additional tests were performed with a liquid with a much higher viscosity. All the requirements of the technical standard ISO 11608-2 were satisfied, and the differences between G29, G33 and G34 were negligible. Therefore, the PiC Insupen needle G33x4mm was chosen as representative of the PiC pen needles. Dose accuracy and needle hub torque were assessed, according to the ISO 11608-2:2012 norms. For pens with variable volume, two different volumes were tested (Vlow and Vhigh) in random order, testing 60 needles with Vlow and 60 with Vhigh.ResultsOverall, 50 different pens were tested. Dose accuracy acceptance criteria were met for all the pens tested, with the only exception of Vhigh for Berlipen Precision pen. The removal torque was adequate for all pens, with the only exception of Berlipen 301 and Berlipen 302 pens.ConclusionWe documented that Pikdare needles are compatible with a large array of different pens for the injection of insulin and other drugs administered subcutaneously.

Effect of Diameter and Fenestration Area of the Liposuction Cannula on the Viability of the Adipocytes.

Loss of volume is perhaps the most frustrating problem of fat grafting. The process of fat grafting depends on different variables such as harvesting, processing, and injection techniques. Results between studies that evaluate the effect of the cannula size on fat graft survival have been controversial. However, the role of the fenestration area of the cannula has not been described. Four custom-made cannulas with a single fenestration were used for this study. Cannulas vary in diameter and area of the fenestration. Healthy patients seeking primary liposuction of the abdomen for aesthetic reasons were included. Lipoaspiration was performed in a clockwise pattern, and the order of the cannulas was rotated. Negative pressure was maintained at 0.8 atm at all times. Ten ml of fat, obtained from the suction tube, was poured into 20-ml conical centrifugal tubes for further processing. One gram of lipoaspirate was extracted from each sample, and acridine orange stain was added. Adipocytes were extracted, extended in a frotis, and observed by a histologist (masked fashion) under fluorescence microscopy. Viability was reported in percentages per sample. The overall viability was 64.75% ± 18.58. The viability of the obtained samples ranged from 66.51± 20.66 % to 62.83 ± 18.1. In further analysis, comparing the viability according to the shaft diameter and fenestration area, there was no significant difference among groups. Neither the diameter of the cannula nor the size of the fenestrations are determining factors to affect the viability of the adipocytes. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Does the Cannula Diameter Affect Outcomes of Temporomandibular Joint (TMJ) Arthrocentesis?

Since its implementation, temporomandibular joint (TMJ) arthrocentesis can be performed with cannulas of different diameters. The aim of this study was to determine the differences in cannula diameter for TMJ arthrocentesis on intraoperative and postoperative parameters. A prospective randomized clinical study was conducted using the documentation of Wilkes stage 3 patients with TMJ disorders. Patients were assigned to 2 groups using a system of computer-assisted randomization. Double puncture arthrocentesis (DPA) was performed with 21-gauge cannulas (group 1) and 18-gauge cannulas (group 2). The primary predictor variable was cannula diameter. Pain values assessed using a Likert-type (0 to10) visual analog scale (VAS) were selected as primary outcome variable. Mandibular movements including maximum mouth opening (MMO), lateral excursions (LE) and protrusion (P), were selected as secondary outcomes. Mandibular movements and pain values were recorded before treatment and at 1st day and 3rd months intervals. Descriptive, comparative, and bivariate analyses were conducted. Intraoperative complications were also recorded. DPA was applied to 33 patients (29 females, 4 males). Although group 1 was found to be significantly more advantageous than group 2 in terms of pain levels (P < .05), no statistically significant difference was discovered in terms of total complication numbers and mandibular movements at the follow-up periods (P >.05). Despite the limited sample size cannula thickness affects postoperative pain level significantly in conventional TMJ arthrocentesis.

Ventilation strategies for front of neck airway rescue: an in silico study

BackgroundDuring induction of general anaesthesia a ‘cannot intubate, cannot oxygenate’ (CICO) situation can arise, leading to severe hypoxaemia. Evidence is scarce to guide ventilation strategies for small-bore emergency front of neck airways that ensure effective oxygenation without risking lung damage and cardiovascular depression. MethodsFifty virtual subjects were configured using a high-fidelity computational model of the cardiovascular and pulmonary systems. Each subject breathed 100% oxygen for 3 min and then became apnoeic, with an obstructed upper airway. When arterial haemoglobin oxygen saturation reached 40%, front of neck airway access was simulated with various configurations. We examined the effect of several ventilation strategies on re-oxygenation, pulmonary pressures, cardiovascular function, and oxygen delivery. ResultsRe-oxygenation was achieved in all ventilation strategies. Smaller airway configurations led to dynamic hyperinflation for a wide range of ventilation strategies. This effect was absent in airways with larger internal diameter (≥3 mm). Intrapulmonary pressures increased quickly to supra-physiological values with the smallest airways, resulting in pronounced cardio-circulatory depression (cardiac output <3 L min−1 and mean arterial pressure <60 mm Hg), impeding oxygen delivery (<600 ml min−1). Limiting tidal volume (≤200 ml) and ventilatory frequency (≤8 bpm) for smaller diameter cannulas reduced dynamic hyperinflation and gas trapping, preventing cardiovascular depression. ConclusionsDynamic hyperinflation can be demonstrated for a wide range of front of neck airway cannulae when the upper airway is obstructed. When using small-bore cannulae in a CICO situation, ventilation strategies should be chosen that prevent gas trapping to prevent severe adverse events including cardio-circulatory depression.

Flow Dynamics and Mixing in Extracorporeal Support: A Study of the Return Cannula.

Cannulation strategies in medical treatment such as in extracorporeal life support along with the associated cannula position, orientation and design, affects the mixing and the mechanical shear stress appearing in the flow field. This in turn influences platelet activation state and blood cell destruction. In this study, a co-flowing confined jet similar to a return cannula flow configuration found in extracorporeal membrane oxygenation was investigated experimentally. Cannula diameters, flow rate ratios between the jet and the co-flow and cannula position were studied using Particle Image Velocimetry and Planar Laser Induced Fluorescence. The jet was turbulent for all but two cases, in which a transitional regime was observed. The mixing, governed by flow entrainment, shear layer induced vortices and a backflow along the vessel wall, was found to require 9–12 cannula diameters to reach a fully homogeneous mixture. This can be compared to the 22–30 cannula diameters needed to obtain a fully developed flow. Although not significantly affecting mixing characteristics, cannula position altered the development of the flow structures, and hence the shear stress characteristics.