Aerosols, airflow, and airspace contamination during laparoscopy.
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ABSTRACT:
SUBMITTER: Hardy N
PROVIDER: S-EPMC8083507 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The relationship between nasal resistance (R) and airspace minimal cross-sectional area (mCSA) remains unclear. After the introduction of acoustic rhinometry, many otolaryngologists believed that mCSA measurements would correlate with subjective perception of nasal airway obstruction (NAO), and thus could provide an objective measure of nasal patency to guide therapy. However, multiple studies reported a low correlation between mCSA and subjective nasal patency, and between mCSA and R. This apparent lack of correlation between nasal form and function has been a long-standing enigma in the field of rhinology. Here we propose that nasal resistance is described by the Bernoulli Obstruction Theory. This theory predicts two flow regimes. For mCSA>Acrit, the constriction is not too severe and there is not a tight coupling between R and mCSA. In contrast, when mCSA<Acrit, nasal resistance is dominated by the severe constriction and it is predicted to be inversely proportional to the minimal cross-sectional area (R?mCSA(-1)). To test this hypothesis, computational fluid dynamics (CFD) simulations were run in 3-dimensional models based on computed tomography scans of 15 NAO patients pre- and post-surgery (i.e., 60 unilateral nasal cavities). Airspace cross-sectional areas were quantified perpendicular to airflow streamlines. Our computational results are consistent with the theory. Given that in most people mCSA>Acrit (estimated to be 0.37cm(2)), this theory suggests that airway constrictions are rarely an exclusive contributor to nasal resistance, which may explain the weak correlation between mCSA and subjective nasal patency.
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Project description:We describe a safe technique for controlled deflation of pneumoperitoneum to facilitate safe laparoscopic surgery in the coronavirus disease 2019 (COVID-19) era.
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Project description:BACKGROUND:The intraoperative classification of appendicitis dictates the patient's postoperative management. Prolonged antibiotic prophylaxis is recommended for complex appendicitis (gangrenous, perforated, abscess), whereas preoperative prophylaxis suffices for simple appendicitis. Distinguishing these two conditions can be challenging. The aim of this study was to assess interobserver variability in the classification of appendicitis during laparoscopy. METHODS:Short video recordings taken during laparoscopy for suspected appendicitis were shown to surgeons and surgical residents. They were asked to: classify the appendix as indicative of no, simple or complex appendicitis; categorize the appendix as normal, phlegmonous, gangrenous, perforated and/or abscess; and decide whether they would prescribe postoperative antibiotics. Inter-rater reliability was evaluated using Fleiss' ? score and the S* statistic. RESULTS:Some 80 assessors participated in the study. Video recordings of 20 patients were used. Interobserver agreement was minimal for both the classification of appendicitis (? score 0·398, 95 per cent c.i. 0·385 to 0·410) and the decision to prescribe postoperative antibiotic treatment (? score 0·378, 0·362 to 0·393). Agreement was slightly higher when published criteria were applied (? score 0·552, 0·537 to 0·568). CONCLUSION:There is considerable variability in the intraoperative classification of appendicitis and the decision to prescribe postoperative antibiotic treatment.
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Project description:We herein describe a novel device to contain droplets and aerosols during phacoemulsification. We modified the silicon phaco test chamber into an aerosol containment chamber (ACC) by shortening the chamber and making a pear-shaped opening at one aspect of its tip. The ACC was fitted over phaco tip such that 4-5 mm of phaco tip and sleeve was exposed. When the phaco tip and irrigation port are inside the anterior chamber during phacoemulsification, the portion of the modified chamber remains around the clear corneal tunnel in an enclosing manner that contains aerosols and droplets.
| S-EPMC8302302 | biostudies-literature
Project description:BackgroundLaparoscopic surgery has progressed rapidly since the early 1990s. For some surgical operations, it has become the standard of care to the extent where open surgery is sometimes looked down upon by some surgical colleagues as well as by patients.Current statusDespite this widespread adoption and acceptance, many surgeons struggle to understand how the laparoscopy stacks work despite having the skills to perform the operation. Most hospitals rely on operating theatre assistants to troubleshoot in the event of problems. This could be potentially unsafe for patients if laparoscopic vision or pneumoperitoneum is lost at a critical point of the operation.DiscussionThere are a number of approaches that have been published for troubleshooting laparoscopy stack. We explore and discuss some of them along with their advantages and disadvantages and how they relate to our methodology and approach. As a product of the discussion, we suggest a systematic way forward to troubleshooting laparoscopic tower equipment problems.ConclusionThe technical knowledge of surgeons and trainees varies widely in the area of laparoscopy-related troubleshooting. This systematic, practical algorithm would help and guide all surgeons to adopt a uniform approach, thereby improving patient safety.
| S-EPMC6754030 | biostudies-literature
Project description:Pharyngeal critical closing pressure (Pcrit) or collapsibility is a major determinant of obstructive sleep apnea (OSA) and may be used to predict the success/failure of non-continuous positive airway pressure (CPAP) therapies. Since its assessment involves overnight manipulation of CPAP, we sought to validate the peak inspiratory flow during natural sleep (without CPAP) as a simple surrogate measurement of collapsibility.Fourteen patients with OSA attended overnight polysomnography with pneumotachograph airflow. The middle third of the night (non-rapid eye movement sleep [NREM]) was dedicated to assessing Pcrit in passive and active states via abrupt and gradual CPAP pressure drops, respectively. Pcrit is the extrapolated CPAP pressure at which flow is zero. Peak and mid-inspiratory flow off CPAP was obtained from all breaths during sleep (excluding arousal) and compared with Pcrit.Active Pcrit, measured during NREM sleep, was strongly correlated with both peak and mid-inspiratory flow during NREM sleep (r = -0.71, p < .005 and r = -0.64, p < .05, respectively), indicating that active pharyngeal collapsibility can be reliably estimated from simple airflow measurements during polysomnography. However, there was no significant relationship between passive Pcrit, measured during NREM sleep, and peak or mid-inspiratory flow obtained from NREM sleep. Flow measurements during REM sleep were not significantly associated with active or passive Pcrit.Our study demonstrates the feasibility of estimating active Pcrit using flow measurements in patients with OSA. This method may enable clinicians to estimate pharyngeal collapsibility without sophisticated equipment and potentially aid in the selection of patients for non- positive airway pressure therapies.
| S-EPMC6084748 | biostudies-other
Project description:The advent of the COVID-19 pandemic led to recommendations aimed at minimizing the risk of gas leaks at laparoscopy. As this has continuing relevance including regarding operating room pollution, we empirically quantified carbon dioxide (CO2) leak jet velocity (important for particle propulsion) occurring with different instruments inserted into differing trocars repeated across a range of intra-abdominal pressures (IAPs) and modern insufflators in an experimental model. Laparoscopic gas plume leak velocity (metres/second) was computationally enumerated from schlieren optical flow videography on a porcine cadaveric laparoscopic model with IAPs of 4-5, 7-8, 12-15 and 24-25 mmHg (repeated with 5 different insufflators) during simulated operative use of laparoscopic clip appliers, scissors, energy device, camera and staplers as well as Veres needle (positive control) and trocar obturator (negative control) in fresh 5 mm and 12 mm ports. Close-fitting solid instruments (i.e. cameras and obturators) demonstrated slower gas leak velocities in both the 5 mm and 12 mm ports (p = 0.02 and less than 0.001) when compared to slimmer instruments, however, hollow instrument designs were seen to defy this pattern with the endoscopic linear stapler visibly inducing multiple rapid jests even when compared to similarly sized clip appliers (p = 0.03). However, on a per device basis the operating instrumentation displayed plume speeds which did not vary significantly when challenged with varying post size, IAP and a range of insufflators. In general, surgeon's selection of instrument, port or pressure does not usefully mitigate trocar CO2 leak velocity. Instead better trocar design is needed, helped by a fuller understanding of trocar valve mechanics via computational fluid dynamics informed by relevant surgical modelling.
| S-EPMC9063625 | biostudies-literature
Project description:Non-invasive quantification of the severity of pharyngeal airflow obstruction would enable recognition of obstructive versus central manifestation of sleep apnoea, and identification of symptomatic individuals with severe airflow obstruction despite a low apnoea-hypopnoea index (AHI). Here we provide a novel method that uses simple airflow-versus-time ("shape") features from individual breaths on an overnight sleep study to automatically and non-invasively quantify the severity of airflow obstruction without oesophageal catheterisation. 41 individuals with suspected/diagnosed obstructive sleep apnoea (AHI range 0-91 events·h-1) underwent overnight polysomnography with gold-standard measures of airflow (oronasal pneumotach: "flow") and ventilatory drive (calibrated intraoesophageal diaphragm electromyogram: "drive"). Obstruction severity was defined as a continuous variable (flow:drive ratio). Multivariable regression used airflow shape features (inspiratory/expiratory timing, flatness, scooping, fluttering) to estimate flow:drive ratio in 136 264 breaths (performance based on leave-one-patient-out cross-validation). Analysis was repeated using simultaneous nasal pressure recordings in a subset (n=17). Gold-standard obstruction severity (flow:drive ratio) varied widely across individuals independently of AHI. A multivariable model (25 features) estimated obstruction severity breath-by-breath (R2=0.58 versus gold-standard, p<0.00001; mean absolute error 22%) and the median obstruction severity across individual patients (R2=0.69, p<0.00001; error 10%). Similar performance was achieved using nasal pressure. The severity of pharyngeal obstruction can be quantified non-invasively using readily available airflow shape information. Our work overcomes a major hurdle necessary for the recognition and phenotyping of patients with obstructive sleep disordered breathing.
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Project description:Asthma exacerbations are associated with subsequent deficits in lung function. Here, we tested the hypothesis that a specific pattern of inflammatory responses during acute exacerbations may be associated with susceptibility to chronic airway obstruction.
2010-03-29 | GSE19903 | GEO
Project description:GW182 (also known asTNRC6) family members are critically involved in the final effector phase of miRNA-mediated mRNA repression. The three mammalian paralogs, TNRC6a, b and c, are thought to be redundant based on Argonaute (Ago) binding, tethering assays, and RNAi silencing of individual members in cell lines. To test this idea, we generated TNRC6a, b and c knockout mice. TNRC6a mutants die at mid-gestation, while b- and c- deleted mice are born at a Mendelian ratio. However, the majority of TNRC6b and all TNRC6c mutants die within 24h after birth, the latter with respiratory failure. Necropsy of TNRC6c mutants revealed normal-appearing airways that give rise to abnormally thick-walled distal gas exchange sacs. Immunohistological analysis of mutant lungs demonstrated a normal distribution of bronchiolar and alveolar cells, indicating that loss of TNRC6c did not abrogate epithelial cell differentiation. The cellular kinetics and relative proportions of endothelial, epithelial, and mesenchymal cells were also not altered. However, the underlying capillary network was simplified and endothelial cells had failed to become tightly apposed to the surface epithelium in TNRC6c mutants, presumably causing the observed respiratory failure. TGFβ family mutant mice exhibit a similar lung phenotype of thick-walled air sacs and neonatal lethality, and qRT-PCR confirmed dynamic downregulation of TGFβ1 and TGFβR2 in TNRC6c mutant lungs during sacculation. VEGFR, but not VEGF-A ligand, was also lower, likely reflecting the overall reduced capillary density in TNRC6c mutants. Together, these results demonstrate that GW182 paralogs are not functionally redundant in vivo. Surprisingly, despite regulating a general cellular process, TNRC6c is selectively required only in the distal lung and not until late in gestation for proper expression of the TGFβ family genes that drive sacculation. These results imply a complex and indirect mode of regulation of sacculation by TNRC6c, mediated in part by dynamic transcriptional repression of an inhibitor of TGFβ family gene expression.
| S-EPMC5634525 | biostudies-literature