Pneumoperitoneum Secondary to Pneumothorax Post-Intubation in a Patient with Difficult Airway

The use of mechanical ventilation can be performed in situations where patients need ventilatory support to maintain adequate oxygenation. Its inappropriate use can cause some complications, among them: pneumothorax and pneumoperitoneum. Our report describes a 28-year-old man admitted to the ICU with a diagnosis of Covid-19 requiring mechanical ventilation with orotracheal intubation due to acute respiratory failure. During the patient’s clinical evolution he presented bilateral pneumothorax with evolution and progression to secondary pneumoperitoneum, where we sought to understand the relationship between the two conditions.

Spontaneous Pneumothorax Mimicking Perforated Viscus in Covid-19 patient

Case presentation: A 65-year-old female diagnosed with COVID-19 developed worsening respiratory distress requiring invasive ventilation. Chest radiography post-intubation revealed air under the diaphragm, pneumomediastinum and subcutaneous emphysema. The case was referred to the surgical team for emergency laparotomy for suspected perforated viscus. Clinically, her abdomen was distended but there was no sign of peritonism. In view of the high risk of perioperative morbidity and absence of peritonism, a CT scan was done to rule out the cause of pneumoperitoneum. CT scan showed bilateral pneumothorax, presence of air in the extra peritoneum and retroperitoneum. There was no air in the peritoneum and no evidence of perforated viscus. She was treated conservatively with bilateral chest tube insertion. Unfortunately, she developed multiorgan failure and succumbed to death.

Anesthesia and Intubation of 10-Day Old C57BL/6J Mouse Pups for Cardiothoracic Surgery

Murine surgical models play an important role in preclinical research. Mechanistic insights into myocardial regeneration after cardiac injury may be gained from cardiothoracic surgery models in 0-14-day-old mice, the cardiomyocytes of which, unlike those of adults, retain proliferative capacity. Mouse pups up to 7 days old are effectively immobilized by hypothermia and do not require intubation for cardiothoracic surgery. Preadolescent (8-14-day-old) mouse pups, however, do require intubation, but this is challenging and there is little information regarding anesthesia to facilitate intubation. Empirical titration of ketamine/xylazine/atropine dosage regimens to body weight indicated the response to anesthesia of 10-day-old C57BL6/J mouse pups of different weights was non-linear, whereby doses of 20/4/0.12 mg/kg, 30/4/0.12 mg/kg and 50/6/0.18 mg/kg, facilitated intubation of pups weighing between 3.15-4.49 g (n=22), 4.50-5.49 g (n=20) and 5.50-8.10 g (n=20), respectively. Lower-body-weight pups required more intubation attempts than heavier pups (p<0.001). Survival post-intubation was inversely correlated with body weight (65, 70 and 80% for low-, mid- and high-weight groups, respectively, R2=0.995). For myocardial infarction surgery after intubation, a surgical plane of anesthesia was induced with 4.5% isoflurane in 100% oxygen and maintained with 2% isoflurane in 100% oxygen. Survival post-surgery was similar for the three weight groups at 92%, 86% and 88% (p=0.91). Together with refinements in animal handling practices for intubation and surgery, and to minimize cannibalization by the dam post-surgery, overall survival for the entire procedure (intubation plus surgery) was inversely correlated with body weight (55%, 60% and 70% for low-, mid- and high-weight groups, respectively, R2=0.978). Given the difficulty encountered with intubation of 10-day old pups and the associated high mortality, we recommend cardiothoracic surgery in 10-day-old pups be restricted to those weighing at least 5.5 g.

A quantitative evaluation of aerosol generation from upper airway suctioning during tracheal intubation and extubation sequences.

Background: Open respiratory suctioning is considered to be an aerosol generating procedure (AGP) and laryngopharyngeal suction, used to clear secretions during anaesthesia, is widely managed as an AGP. It is uncertain whether such upper airway suctioning should be designated an aerosol generating procedure (AGP) because of a lack of both aerosol and epidemiological evidence of risk. Aim: To assess the relative risk of aerosol generation by upper airway suction during tracheal intubation and extubation in anaesthetised patients. Methods: Prospective environmental monitoring study in ultraclean operating theatres to assay aerosol concentration during intubation and extubation sequences including upper airway suctioning for patients undergoing surgery (n=19 patients). An Optical Particle Sizer (particle size 300nm-10μm) was used to sample aerosol 20cm above the mouth of the patient. Baseline recordings (background, tidal breathing and volitional coughs) were followed by intravenous induction of anaesthesia with neuromuscular blockade. Four periods of oropharyngeal suction were performed with a Yankauer sucker: pre-laryngoscopy, post-intubation and pre- and post-extubation. Findings: Aerosol from breathing was reliably detected (65[39-259] particles.L-1 (median[IQR])) above background (4.8[1-7] particles.L-1, p<0.0001 Friedman). The procedure of upper airway suction was associated with much lower average concentrations of aerosol than breathing (6.0[0-12] particles.L-1, P=0.0007) and was indistinguishable from background (P>0.99). The peak aerosol concentration recorded during suctioning (45[30-75] particles.L-1) was much lower than both volitional coughs (1520[600-4363] particles.L-1, p<0.0001, Friedman) and tidal breathing (540[300-1826] particles.L-1, p<0.0001, Friedman). Conclusion: The procedure of upper airway suction during airway management is associated with no higher concentration of aerosol than background and much lower than breathing and coughing. Upper airway suction should not be designated as a high risk AGP.

Is Duration of Endotracheal Tube Intubation Using a Video Laryngoscope Different with a Direct Laryngoscope in Elective Surgery Patients During Pandemic Covid-19?

Introduction: Aerosol box is a usefull tools to prevent aerosol and droplet contaminations during laryngoscopy and intubation in COVID-19 pandemic. Video laryngoscope is recommended during this era to increase the operator and patient’s distance during the procedure. However, many anesthesiologists still use direct laryngoscopes due to their availability and familiarity. This study aims to compare endotracheal tube intubation with video laryngoscope compared to direct laryngoscope in elective surgery patients. Methods: This study was a quasi-experimental study. The sample size in each group (video and direct laryngoscope) was 35 subjects. The primary outcome of this study was to compare the duration of intubation between video laryngoscope and direct laryngoscope, while the secondary outcome was to evaluate complications such as broken teeth and sore throat 24 hours post intubation. Results: Direct laryngoscope had shorter intubation duration than video laryngoscope [12.3 (8.9-21.0) vs 13.3 (11.4 – 21.6; p =0.07) respectively. Two complication reported on video laryngoscope groups. Conclusion: Duration of ETT intubation using a direct laryngoscope was shorter during intubation with aerosol box compared to video laryngoscope in elective surgery patients. The box which was being used may limit the space of movement making it difficult to intubate.

Abstract 13216: Initial Survey of Respiratory Mechanics During Prehospital Bag Ventilation

Introduction: Respiratory mechanics, such as tidal volume and inspiratory pressures, affect outcome in hospitalized patients with respiratory failure. The ability to accurately measure respiratory mechanics in the prehospital setting is limited, thus the relationship between prehospital respiratory mechanics and clinical outcome is not well understood. In this feasibility study, we examined respiratory mechanics of bag-valve mask (BVM) ventilation by emergency medical services (EMS) using a novel in-line measuring device during a period when agencies switched from larger to smaller ventilation bags. Methods: This prospective cohort study included a convenience sample of adult patients who received BVM ventilation by EMS, from August 2018 to January 2020, in Bellevue, Washington. The airway monitoring device was applied by paramedics after intubation to passively record in black box mode, until termination of efforts or hospital arrival. Respiratory parameters included tidal volume, airway pressure, flow rates, end-tidal carbon dioxide, and respiratory rate. Prehospital agencies transitioned from large (1500 mL) to small (1000 mL) ventilation bags during the study period. Results: 7371 post-intubation breaths were measured in 54 patients, 32 treated for out-of-hospital cardiac arrest (OHCA) and 22 treated for non-arrest conditions, primarily respiratory etiology. EMS ventilated 19 patients with a small bag and 35 patients with a large bag. Ventilation with a smaller bag was characterized by less variability in tidal volumes and higher proportion of breaths delivered within 4-10 mL/kg of predicted body weight (Figure) (p<0.05). Conclusions: Respiratory mechanics can be measured in EMS patients receiving BVM ventilation following intubation. Ventilation with a smaller bag might reduce variation in tidal volume, but further study is needed. These data provide the first evaluation of respiratory mechanics during manual ventilation provided by EMS.