Reservoir Bag Research Articles

Efficacy of high-flow nasal oxygen therapy in cancer patients with concurrent acute hypoxemic respiratory failure: a retrospective propensity score study.

Acute respiratory failure is the leading cause of intensive care unit (ICU) admission of cancer patients. Studies of the efficacy of high-flow nasal cannula (HFNC) therapy were rarely conducted in cancer populations. We here compared the clinical effects of HFNC therapy and conventional oxygen therapy (COT) in cancer patients with concurrent acute hypoxemic respiratory failure (AHRF). In this single-center retrospective study, cancer patients with concurrent acute hypoxic respiratory failure either received initial oxygen therapy via HFNC (HFNC group, 68 patients) or received initial oxygen therapy via a nasal cannula, simple mask, or mask with reservoir bag (COT group, 133 patients). Groups were propensity score matched. Differences in respiratory rate (RR), heart rate (HR), and PaO2/FiO2 ratio before and after treatment in the two groups were compared using a mixed-effects model. The 28-day mortality risk was explored using a Cox proportional hazards model. The 24-h and 48-h PaO2/FIO2 ratios were significantly higher in the HFNC than in the COT group (210.5mmHg vs. 178.5mmHg; P < 0.01; 217.1mm Hg vs. 181.6mm Hg; P < 0.01, respectively). Differences in RR and HR between the groups at each time point were nonsignificant. The 28-day mortality rate was 17.4% vs. 38.1% for the HFNC and COT groups, respectively (P < 0.01). Hazard ratio was significantly higher for COT group (HR 2.6, 95% confidence interval 1.3, 5.3). Compared with COT, HFNC use for initial oxygen therapy can improve PaO2/FIO2 ratio and survival rate in cancer patients with AHRF.

An Innovative Technique to Prevent Air Leaks from Cervical Esophagostomy during Face Mask Ventilation.

The objective of the study was to report the indigenous use of an electrocardiography (ECG) electrode in successfully occluding the Cx-esophagostomy to prevent inadvertent loss of tidal volume. Twenty-nine observations were recorded on 27 patients (mean age: 10.9 months; male:female = 2.6:1). The oral cavity, pharynx, and Cx-esophagostomy were cleared of saliva. Peristomal area was cleaned with dry gauze and dried with alcohol. Latex-free, 50 mm, ECG electrode was pasted symmetrically over the Cx-esophagostomy. The efficacy of the electrode was assessed using a five-point algorithm: (i) collapse of reservoir bag, (ii) chest expansion, (iii) ballooning of electrode, (iv) cotton-wisp test, and (v) change in compliance with manual compression of the electrode. Subgroup analysis was conducted for laterality and health of Cx-esophagostomy. Study cohort: Cx-esophagostomy was located on the left in 58.26% (n = 17/29) patients. The health of Cx-esophagostomies was graded from I to IV (n = 9, 16, 3, and 1, respectively). The collapse of the reservoir bag and chest rise indicated successful ventilation. Ballooning of the electrode with each breath was observed in 79% (23/29) patients. Partial separation of the electrode from the skin (exaggerated with each breath) was observed in 10.3% (3/29) patients (Group I: n = 1, Group III: n = 1, and Group IV: n = 1). This was related to poor local preparation or pooling of saliva (n = 1; Group I: resolved with procedural re-application of a fresh electrode) and underlying skin condition (n = 2; Groups III and IV: resolved only temporarily with re-application). The cotton-wisp test was positive in two additional patients (1 each in Groups II and III) and was related to the pooling of saliva. No change in compliance was observed with manual compression of the electrode. No difference in success was observed between left and right Cx-esophagostomies. Overall success with this technique was 82.8% with a potential for 100% in those with peristomal health graded I-III. The ECG electrode is a technically simple, cost-effective, and widely available device, instrumental in addressing the problem of air leak through Cx-esophagostomy during face mask ventilation before intubation.

PneumoniaCheck, a novel aerosol collection device, permits capture of airborne Mycobacterium tuberculosis and characterisation of the cough aeromicrobiome in people with tuberculosis

BackgroundTuberculosis (TB), a major cause of disease and antimicrobial resistance, is spread via aerosols. Aerosols have diagnostic potential and airborne-microbes other than Mycobacterium tuberculosis complex (MTBC) may influence transmission. We evaluated whether PneumoniaCheck (PMC), a commercial aerosol collection device, captures MTBC and the aeromicrobiome of people with TB.MethodsPMC was done in sputum culture-positive people (≥ 30 forced coughs each, n = 16) pre-treatment and PMC air reservoir (bag, corresponding to upper airways) and filter (lower airways) washes underwent Xpert MTB/RIF Ultra (Ultra) and 16S rRNA gene sequencing (sequencing also done on sputum). In a subset (n = 6), PMC microbiota (bag, filter) was compared to oral washes and bronchoalveolar lavage fluid (BALF).Findings54% (7/13) bags and 46% (6/14) filters were Ultra-positive. Sequencing read counts and microbial diversity did not differ across bags, filters, and sputum. However, microbial composition in bags (Sphingobium-, Corynebacterium-, Novosphingobium-enriched) and filters (Mycobacterium-, Sphingobium-, Corynebacterium-enriched) each differed vs. sputum. Furthermore, sequencing only detected Mycobacterium in bags and filters but not sputum. In the subset, bag and filter microbial diversity did not differ vs. oral washes or BALF but microbial composition differed. Bags vs. BALF were Sphingobium-enriched and Mycobacterium-, Streptococcus-, and Anaerosinus-depleted (Anaerosinus also depleted in filters vs. BALF). Compared to BALF, none of the aerosol-enriched taxa were enriched in oral washes or sputum.InterpretationPMC captures aerosols with Ultra-detectable MTBC and MTBC is more detectable in aerosols than sputum by sequencing. The aeromicrobiome is distinct from sputum, oral washes and BALF and contains differentially-enriched lower respiratory tract microbes.

Sequential Oxygen Therapy in COVID-19 Diabetic Patients: A Retrospective Cohort Study

Introduction: Acute respiratory failure is the most common clinical feature in patients with severe Coronavirus Disease -2019 (COVID-19) who are admitted to an Intensive Care Unit (ICU) and may require invasive mechanical ventilation, which is generally linked with a high fatality rate. Patients with established co-morbidities, such as diabetes, invariably fall into the category of patients with severe disease presentation and rapid disease progression. Aim: To study the clinical outcomes of COVID-19 diabetic patients after sequential oxygen therapy using a reservoir bag mask, High Frequency Nasal Oxygen (HFNO), and Non-invasive Ventilation (NIV). Materials and Methods: In this retrospective cohort study, adhering to the STROBE statement criteria, the authors included 150 patients suffering from COVID-19 acute respiratory failure, who were known diabetics, divided into three groups based on admission oxygen saturation and Respiratory Rate (RR) for Non-Rebreather Bag-Mask (NRBM) therapy, HFNO, and NIV. For two weeks, all patients were monitored, and measures such as Saturation of peripheral Oxygen (SpO2 ), Respiratory Rate (RR) escalation of oxygen requirement, glycaemic management, compliance and problems with continued oxygen therapy, the need for invasive mechanical ventilation, and mortality were recorded. The recorded parameters among the three groups were compared using Analysis of Variance (ANOVA) test. Results: Among the demographic parameters recorded, the authors noted that individuals older than 50-55 years of either sex were admitted for HFNO (56.02±11.71 years) and NIV (54.28±14.67 years) therapy, whereas no such preponderance was noted among the two genders. Significant results were noted in all three groups in terms of the escalation of oxygen fraction (FiO2) requirements on the 10th day of observation (NRBM 12.63±2.48%, HFNO 37.74±13.56%, NIV 82.44±11.11%). The need for tracheal intubation was higher in patients in the NIV group (10) compared to the HFNO (9) and NRBM (1) groups. Patients whose blood sugar levels remained uncontrolled throughout the course of observation in the study were disparagingly seen to have been a part of the HFNO and NIV groups, and hence the subsequent mortality. Conclusion: There was a steady escalation of mean oxygen requirements in all three groups of oxygen therapy over the course of two weeks, coinciding with the ensuing ‘cytokine storm’ associated with Severe Acute Respiratory SyndromeCoronavirus- 2 (SARS-CoV-2) infection. This trend of escalation of oxygen requirement also in turn coincided with the raised glycaemic charting trends of the patients over the same course of two weeks, delineating those individuals with diabetes mellitus, in view of their compromised immunity and innate pro -inflammatory state, are more prone to develop severe form of the disease with more serious complications, which may even lead to mortality. With regards to the compliance, NRBM &amp; HFNO provided best results in comparison to NIV. The rates of complications were also noted to be higher with the use of NIV in this instance.

Ventilation failure following misconnection of reservoir bag to the scavenging system exhaust port - A case study.

Ventilation failure following misconnection of reservoir bag to the scavenging system exhaust port - A case study.

Comparison of the Effectiveness of Nasal Cannula Versus Face Mask With Reservoir Bag in Postoperative Patients Undergoing General Anesthesia: A Prospective Randomized Controlled Trial.

High-concentration oxygen delivery via a face mask (FM) with a reservoir bag is a common practice to prevent postoperative hypoxemia; however, it may also lead to atelectasis and other respiratory complications. Lower concentrations delivered via nasal cannula (NC) may be equally effective in preventing postoperative hypoxemia. The present study aimed to compare peripheral oxygen saturation (SpO_2) delivered via NC versus FM with a reservoir bag in patients who have undergone general anesthesia (GA). Eighty-four patients scheduled for GA were randomized to receive either oxygen via NC (NC group, n = 42) or FM with a reservoir bag (FM group, n = 42) for 30 minutes after GA at a postanesthesia care unit (PACU). All patients were assessed based on SpO_2 value, adverse events, and patient satisfaction (measured using a 100-mm visual analog scale). The overall difference between groups in the change of SpO_2 over 30 minutes at the PACU was -0.004 (95% confidence interval, -0.015 to 0.008; P = 0.527). SpO_2 during the first five minutes was lower in NC group, but the difference was not statistically significant. No desaturation occurred in either group, and there was no observed difference between groups in terms of adverse events. Patient satisfaction scores were also similar (P = 0.612). Oxygen supplementation via NC and via FM with a reservoir bag were equally effective in preventing postoperative hypoxemia after GA.

The Autumn Ghost. How the Battle Against a Polio Epidemic Revolutionized Modern Medical Care

The Autumn Ghost. How the Battle Against a Polio Epidemic Revolutionized Modern Medical Care

Inhalational anaesthetics: an assessment of agent delivery and capture.

Inhalational anaesthetics: an assessment of agent delivery and capture.

Amitraz poisoning – A rare and uncommon case of poisoning and its management

A 25-year-old male presented to the peripheral hospital with an alleged history of ingestion of amitraz toxin 12.5% (approximately 150 mL), and presented with complaints of nausea, vomiting, abdominal pain, and weakness. On examination, he was conscious but disoriented and agitated, oxygen saturation (SpO2) was 89%–90% on room air, pulse rate was 40/min, blood pressure (BP) was 110/70 mmHg, and bilateral (B/L) crepitations were present on auscultation. Emergency treatment included – intravenous(IV) fluid, atropine 0.6 mg IV, and gastric lavage. Oxygen was given through an oxygen mask with a reservoir bag at 10 L/min. After some time, the patient's Glasgow Coma Scale (GCS) started deteriorating, and arterial blood gas (ABG) analysis revealed severe acidosis with pH of 7.109, pCO2 – 73, and HCO3 – 23.1, and immediately, the patient was transferred to a higher center given falling GCS, decreased saturation, and ABG finding. On presentation in the emergency department in our tertiary care center, the patient was unconscious, SpO2 was 69% on oxygen nonrebreathing mask – NRBM Mask at 15 L, BP was 128/78 mmHg, pulse rate was 104/min, and B/L crepitations were present on auscultation. The patient was immediately intubated in casualty and shifted to the intensive care unit for further management. Amitraz is a triazapentadiene, 1,5 di (2,4 dimethylphenyl) 3 methyl 1,3,5 triaza penta 1,4 diene, a formamidine pesticide, α2 adrenergic agonist in the central nervous system belongs to the amidine chemical family. The systemic effect of amitraz toxin is due to the activation of the pure α2-adrenergic agonist. It is a rare kind of poisoning in humans, and there exists a paucity of literature on the management of the aforementioned poisoning. Only a limited number of case reports of human intoxication have been published and most of them are of accidental ingestion by children. Due to insubstantial data on its management, this case report will be advantageous for practitioners working in emergency and intensive care departments.

Comparison of FDO2 at different flow rates in an adult manual resuscitator with and without reservoir bag: A manikin study

Comparison of FDO2 at different flow rates in an adult manual resuscitator with and without reservoir bag: A manikin study

Graded oxygen delivery using low flow rotameter during positive pressure ventilation using self-inflating bag with a leak - an experimental study

Introduction: Bag-mask ventilation does not always guarantee 100% seal around airway opening and hence delivered fraction of oxygen (FDO2) may vary. Aim: To determine the FDO2 via a standard neonatal selfinflating bag with and without application of leak, without a reservoir bag with flow rates of 0.1, 0.2, 0.4, 0.6, 0.8, 1, 2, 4 and 6 L/min. Method: A test lung with a three way rotator to produce 0%, 30%, 50% and 75% leak was connected to a 3.5 mm ID endotracheal tube (ETT) connected to a VBM standard preterm self-inflating bag of 250 mL without a reservoir. The ETT was connected to ENVENTEC oxygen analyser and the bag inlet to a 100% oxygen source. Ventilation was done to a peak pressure of 15-20 cm H2O, at 40 bpm. FDO2 was recorded every 30 s, until the difference between two consecutive values was ≤1%. Result: The change in FDO2 was maximum when compared between 0.1 L/min and 6 L/min. For all leak percentages, the delivered oxygen showed an increasing trend from 0.1 to 0.6 L/min, a plateau from 0.6 to 1 L/min after which it increased. The change in FDO2 was different for different flow rates among various leak percentages. The highest delivered oxygen without leak was 56.15 ± 3.45% with 4 L/min flow. The oxygen delivered with 70% leak was considerably lower when compared to values with different leaks with respective flow rates. Conclusion: FDO2 increases with oxygen flow rates greater than 1 L/min. Leak around the mask has no effect of FDO2. Equilibration of FDO2 is achieved with in 60-90 s.

Guide to manual positive pressure ventilation (bagging) in companion animal practice

Background: Squeezing the reservoir bag on the anaesthetic breathing system to inflate the lungs (colloquially known as bagging) is a technique commonly used during general anaesthesia in veterinary practice. Despite being straightforward to perform, the physiological implications are important to understand. Furthermore, catastrophic consequences can occur and staff must be vigilant and trained correctly when using this technique to manage ventilation during anaesthesia.Aim of the article: This article provides an overview of the indications and contraindications of manual bagging, and reviews relevant literature from human medicine.

Diathermy smoke induced asthmatic attack during transurethral resection of prostate

The use of diathermy and other electrosurgical devices have become an indispensible and integral part of modern surgical practice. This revolutionary benefit to surgery have been associated with the release of toxic agents that represents a potential health risk. A 79 year old who had an asthmatic attack during transurethral resection of prostate (TURP) on account of benign prostate enlargement. He was a known asthmatic, incidence of attacks had become infrequent over the years, and the last asthmatic attack was over 10 years ago. Triggers for attacks were strong smell, smoke and dusty environment. He had no other systemic disease of note. The procedure was done under subarachnoid block. Thirty minutes into the procedure, he was noticed to have difficulty in breathing and coughing, there was tachycardia and elevated blood pressure. The patient oxygen saturation was between 88-92% on room air, chest auscultation revealed a wide spread rhonchi. Oxygen via a non-rebreather face mask with reservoir bag at 10L/min was commenced and intravenous hydrocortisone 200mg was given. Forty minutes into the procedure, patient’s condition did not improve. Procedure was discontinued and patient moved to the ward, patient was nebulized, intravenous aminophylline 250 mg given slowly, with repeated nebulization and continued oxygenation, patient condition improved. An immediate postoperative serum electrolyte, urea and creatinine done showed normal values to rule out TURP syndrome.

Machine learning-based model for prediction of clinical deterioration in hospitalized patients by COVID 19

Despite the publication of great number of tools to aid decisions in COVID-19 patients, there is a lack of good instruments to predict clinical deterioration. COVID19-Osakidetza is a prospective cohort study recruiting COVID-19 patients. We collected information from baseline to discharge on: sociodemographic characteristics, comorbidities and associated medications, vital signs, treatment received and lab test results. Outcome was need for intensive ventilatory support (with at least standard high-flow oxygen face mask with a reservoir bag for at least 6 h and need for more intensive therapy afterwards or Optiflow high-flow nasal cannula or noninvasive or invasive mechanical ventilation) and/or admission to a critical care unit and/or death during hospitalization. We developed a Catboost model summarizing the findings using Shapley Additive Explanations. Performance of the model was assessed using area under the receiver operating characteristic and prediction recall curves (AUROC and AUPRC respectively) and calibrated using the Hosmer–Lemeshow test. Overall, 1568 patients were included in the derivation cohort and 956 in the (external) validation cohort. The percentages of patients who reached the composite endpoint were 23.3% vs 20% respectively. The strongest predictors of clinical deterioration were arterial blood oxygen pressure, followed by age, levels of several markers of inflammation (procalcitonin, LDH, CRP) and alterations in blood count and coagulation. Some medications, namely, ATC AO2 (antiacids) and N05 (neuroleptics) were also among the group of main predictors, together with C03 (diuretics). In the validation set, the CatBoost AUROC was 0.79, AUPRC 0.21 and Hosmer–Lemeshow test statistic 0.36. We present a machine learning-based prediction model with excellent performance properties to implement in EHRs. Our main goal was to predict progression to a score of 5 or higher on the WHO Clinical Progression Scale before patients required mechanical ventilation. Future steps are to externally validate the model in other settings and in a cohort from a different period and to apply the algorithm in clinical practice.Registration: ClinicalTrials.gov Identifier: NCT04463706.

Laporan Kasus : Krisis Hiperglikemi pada Pasien Diabetes Wanita Usia 45 tahun dengan Edema Paru

Hyperglycemic crisis is a metabolic emergency that causes morbidity or death. Diabetic Ketoacidosis (DKA), and Hyperosmolar Hyperglycemic State (HHS), are 2 forms of hyperglycemic crisis that often occur in patients with uncontrolled diabetes mellitus. A 45-year-old female patient came to the hospital emergency department with decreased consciousness since 12 hours and shortness of breath since 2 days. The patient has a history of diabetes mellitus. On physical examination, E2V2M4 consciousness, blood pressure 140/90, oxygen saturation 40% with a reservoir bag oxygen mask 15 liters per minute, coarse rhonchi and chest retractions. From the results of investigations, there was an increase in blood glucose (523 mg/dL), a chest X-ray of pulmonary edema and bilateral bronchopneumonia. The patient was diagnosed with a hyperglycemic crisis with unstable hemodynamics. However, before being transferred to the intensive care unit, the patient was declared dead. Hyperglycemic crisis is a metabolic emergency whose management must be fast and appropriate in order to maintain hemodynamic stability and prevent death Keyword :Diabetes, Diabetic ketoacidosis, Hyperglycemic crisis, Hyperosmolar hyperglycemic state

Double trouble - Airway equipment problem in a difficult airway!

Sir, A 11-year-old boy weighing 29 kg was posted for pelvic supporting osteotomy with limb lengthening and external fixation. He had a history of sepsis in infancy with post-sepsis sequelae and resultant limb length discrepancy. The patient also had surgery six years ago for posttraumatic bilateral temporomandibular ankylosis. Bilateral distraction osteotomy followed by release of ankylosis was performed in a two-stage procedure. On examination, he had micrognathia and retrognathia, with a mouth opening restricted to 2 cm [Figure 1]. He was otherwise healthy, and blood investigations were within normal limits.Figure 1: (a) Patient profile showing significant retrognathia (b) Limited mouth openingWe anticipated a difficult airway and planned to conduct the case under general anaesthesia using supraglottic airway device (SAD), with femoral nerve block for analgesia. Plan B, in case SAD insertion failed, was fibreoptic-guided tracheal intubation. The operating room preparation included difficult airway cart and team briefing about the airway plan. An intravenous line was secured prior to induction. The child was very anxious, so 1 mg midazolam was administered under monitoring. Following administration of glycopyrrolate 4 μg/kg and fentanyl 2 μg/kg, inhalational induction with incremental sevoflurane in 100% oxygen was performed. Once ability to mask ventilate was confirmed, we administered propofol 3 μg/kg. Laryngeal mask airway (LMA) Supreme® size 2.5 was chosen (over our standard preference of i-gel® airway) since it has a rather lean profile which we thought would easily fit into the narrow oral cavity. LMA insertion was easy, and adequate ventilation was achieved with a good seal. Muscle relaxant was avoided and patient was ventilated on pressure support mode with oxygen, air and sevoflurane using low flow anaesthesia. Midway through the procedure, the attending anaesthetist (our fellow in paediatric anaesthesia) noticed that the ventilator bellows had suddenly collapsed and the end-tidal carbon dioxide (EtCO2)value fell from 35 mmHg to 20 mmHg. He immediately took the reservoir bag in hand and started manual ventilation with 100% oxygen. The consultant anaesthetist was called for help and manual ventilation revealed a large leak in the LMA. Functional airway obstruction (laryngospasm, bronchospasm), shifting of the LMA were some of the differentials that came to mind. 1 mg/kg of propofol was administered and decision to change the LMA was taken. The orthopaedic surgeons were informed about the problem and requested to stop surgery. When the tapes securing the LMA were removed and the LMA Supreme® was taken out, we noticed a breach at proximal end at the junction of the bite block, causing the massive leak and loss of ventilation [Figure 2]. Another LMA Supreme® was inserted and the rest of the case proceeded uneventfully. Prompt detection, identification of the problem and timely intervention prevented fall in oxygen saturation. We are a close-knit team of paediatric anaesthetists, fellows and experienced technicians, and the shared understanding of the case ensured efficient crisis management.Figure 2: LMA Supreme® with arrow indicating site of breakage at the junction of shaft with the bite portionWe did a root cause analysis and also conducted a team debriefing after the case. The LMA Supreme® used was a near expiry device, and we believe it may have deteriorated during storage leading to the breakage. On performing a literature search, we found a report of breakage of LMA Supreme® similar to our case.[1] We decided to send this communication for publication to highlight the following points. A visual inspection to confirm the integrity of the airway device and the cuff (in case of cuffed SADs) should be part of the mandatory anaesthesia trolley pre-check. Excessive reuse of reusable SADs can also result in damage.[2] Team briefing is vital prior to every case; especially so for difficult cases. Wherever possible, in DA cases, spontaneous ventilation, avoidance of muscle relaxant and “not to burn bridges” is a sensible, safe approach.[3] Age and weight appropriate “standby” equipment should be immediately available for rescue, such as in our case. Soft skills, for example, team work and communication play an important role in crisis management. Debriefing with the entire team is equally important after critical events to assess and improve team performance and to promote a culture of safety. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Subxiphoid Video-Assisted Thoracoscopic Surgery for Lung Resection Under Spontaneous Ventilation: Case Report

This case report describes two patients that underwent successful video-assisted thoracoscopic surgery (VATS) lung resections under spontaneous ventilation using the uniportal subxiphoid approach. The authors performed lung wedge resection in both patients under local anesthesia without using of a Foley catheter, arterial line, or intercostal chest drain. Only intravenous drugs and an oxygen mask with reservoir bag were used. The postsurgical course for both patients was uneventful. Both were discharged on postoperative day 2 and were doing well at 1- and 3-month follow-ups. Keywords: Subxiphoid approach; Pulmonary resection; Lung cancer

Non-intubated video-assisted thoracoscopic surgery for pulmonary resection in children

7-years old boy whom was diagnosed as an invasive aspergillosis. His underlying disease was B-cell acute lymphoblastic leukemia. We successfully performed right lower lung wedge resection under intravenous anesthesia without use of a Foley catheter, arterial line, or endotracheal tube. Only intravenous drugs and an oxygen mask with reservoir bag were used. The postsurgical course was uneventful. He was discharged on postoperative day 3 and were doing well at 1- and 3-month follow-ups.

Retinal Vascular Response to Hyperoxia in Patients with Diabetes Mellitus without Diabetic Retinopathy

Purpose To evaluate the retinal vascular response to hyperoxia in patients with diabetes at the preclinical stage of diabetic retinopathy (DR) and to quantify the changes in comparison with normal subjects using optical coherence tomography angiography (OCTA). Methods In this prospective study, 40 eyes of 20 participants comprising 10 diabetic patients with no diabetic retinopathy (NDR) and 10 normal subjects were recruited. OCTA images were acquired in the resting position and were repeated after a hyperoxic challenge using a nasal mask connected to a reservoir bag supplying 100% oxygen at the rate of 15 L per minute for 5 minutes. The changes of mean parafoveal vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), the foveal avascular zone (FAZ) size, and the outer retina flow index were compared between two conditions in each group and between the two study groups. The statistical significance of differences in the means was evaluated using Student's t-test for unpaired samples with consideration of the generalized estimating equations (GEE) for intereye correlation. Results At baseline, the mean parafoveal VD of SCP and DCP were significantly lower in the NDR participants compared to the healthy subjects (P < 0.001 and P = 0.006, respectively). After induction of the hyperoxic challenge in healthy participants, mean parafoveal VD reduced at both the SCP and DCP, but reached a statistical significance only in DCP (P = 0.006). However, following induction of hyperoxic challenge in patients with NDR, no significant decline was noticed in mean parafoveal VD of SCP and DCP. The degree of change in mean parafoveal VD of DCP was statistically significantly more pronounced in healthy subjects compared to the NDR group (P = 0.034). The change in FAZ size and the outer retina flow index were comparable between the two study groups. Conclusion Retinal capillary layers responded differently to hyperoxia-induced challenge, and in normal subjects, the autoregulatory mechanism was mostly effective in the parafoveal DCP. Retinal vascular reactivity was impaired in SCP and DCP at the preclinical stage of DR. OCTA as a noninvasive modality was able to quantify the retinal vascular response to the hyperoxic challenge.

Twisting of Tail End of the Reservoir Bag Malingering as Stuck Valve during Positive-pressure Ventilation

Twisting of Tail End of the Reservoir Bag Malingering as Stuck Valve during Positive-pressure Ventilation