Development and assessment of the performance of a shared ventilatory system that uses clinically available components to individualize tidal volumes.

OBJECTIVES: To develop and assess a system for shared ventilation using clinically available components to individualize tidal volumes. DESIGN: Evaluation and in vitro validation study SETTING: Ventilator shortage during the SARS-CoV-2 pandemic. PARTICIPANTS: The team consisted of physicians, bioengineers, computer programmers, and medical technology professionals. METHODS: Using clinically available components, a system of ventilation consisting of two ventilatory limbs was assembled and connected to a ventilator. Monitors for each limb were developed using open-source software. Firstly, the effect of altering ventilator settings on tidal volumes delivered to each limb was determined. Secondly, the impact of altering the compliance and resistance of one limb on the tidal volumes delivered to both limbs was analysed. Experiments were repeated three times to determine system variability. RESULTS: The system permitted accurate and reproducible titration of tidal volumes to each limb over a range of ventilator settings and simulated lung conditions. Alteration of ventilator inspiratory pressures, of respiratory rates, and I:E ratio resulted in very similar tidal volumes delivered to each limb. Alteration of compliance and resistance in one limb resulted in reproducible alterations in tidal volume to that test lung, with little change to tidal volumes in the other lung. All tidal volumes delivered were reproducible. CONCLUSIONS: We demonstrate the reliability of a shared ventilation system assembled using commonly available clinical components that allows titration of individual tidal volumes. This system may be useful as a strategy of last resort for Covid-19, or other mass casualty situations, where the need for ventilators exceeds supply.

Aerosolized intraperitoneal local anesthetic for laparoscopic surgery: a randomized, double-blinded, placebo-controlled trial.

BACKGROUND: Postoperative pain remains a significant challenge following laparoscopy. Aerosolized intraperitoneal local anesthetic (AILA) is a novel method to deliver local anesthetic. The aim was to evaluate aerosolized ropivacaine in pain management following laparoscopic Nissen fundoplication (LNF) and cholecystectomy (LC). METHODS: This prospective randomized double-blinded placebo-controlled trial enrolled consecutive patients undergoing LNF and LC. The treatment group (TG) received intraperitoneal ropivacaine (5 mL 1 % Naropin(®)) at CO2 insufflation via the AeroSurge(®) aerosolizer device through the camera port. The control group (CG) received 5 mL of saline in the same manner. Postoperative shoulder tip pain at rest 6 h postoperatively was the primary study endpoint, with secondary endpoints of shoulder and abdominal pain within the first 24 h, recovery room stay, hospital stay, and postoperative analgesia use. Pain scores were collected using the Verbal Rating Score. RESULTS: Eighty-seven patients were included in the final analysis (TG n = 40, CG n = 47). There was no significant difference between CG and TG at the primary endpoint. In the LC group, AILA significantly reduced shoulder tip pain at rest at 10 (p = 0.030) and 30 min (p = 0.040) and shoulder tip pain on movement at 10 (p = 0.030) and 30 min (p = 0.037). In the LNF group, AILA significantly reduced postoperative abdominal pain at rest at 6 h (p = 0.009). AILA reduced overall incidence of shoulder tip pain in the LC group (11.8 vs. 57.9 %, p = 0.004). CONCLUSION: This study did not demonstrate a significant difference between TG and CG in the primary endpoint, pain at 6 h postoperatively.

Total systemic ropivacaine concentrations following aerosolized intraperitoneal delivery using the AeroSurge.

STUDY OBJECTIVE: To evaluate intraperitoneal ropivacaine delivery with the AeroSurge device in the clinical setting and to evaluate the total systemic ropivacaine levels achieved following delivery of 50 mg of aerosolized ropivacaine. DESIGN: Preliminary, prospective, nonrandomized study. SETTING: Operating room of a university hospital. PATIENTS: 5 consecutive ASA physical status 1 and 2 patients undergoing elective laparoscopic Nissen fundoplication or cholecystectomy. INTERVENTION: Five mL of 1% ropivacaine was delivered through the 10 mm port using the AeroSurge device at peritoneal insufflation. MEASUREMENTS: Venous blood samples were collected and total ropivacaine concentration was determined using liquid chromatography-mass spectrometry. MAIN RESULTS: The AeroSurge device delivered ropivacaine, visible as mist within the peritoneal cavity. Peak concentration (Cmax) was attained between 10 and 30 minutes following the end of aerosolized ropivacaine delivery. At no stage did any level approach toxic levels. CONCLUSIONS: This preliminary study confirms that aerosolized intraperitoneal local anesthetic is feasible, with ropivacaine concentrations remaining within safe levels.

Surgery induces cyclooxygenase-2 expression in the rat cervical spinal cord.

BACKGROUND AND OBJECTIVES: Nonsteroidal anti-inflammatory drugs with a selective cyclooxygenase-2 (COX-2) inhibitory profile are effective analgesics in the postoperative period. This implies that surgery induces COX-2 biosynthesis. We examined whether peripheral surgical trauma can induce COX-2 expression in the rat cervical spinal cord. METHODS: Sprague-Dawley rats were divided into 2 groups. The control group underwent general anesthesia but had no surgery. The surgical group underwent general anesthesia and surgical exposure of neck structures. After 14 days, the animals were euthanized, and a section of cervical spinal cord was taken to identify COX-1 and COX-2 expression by immunohistochemical analysis. Two independent blinded observers analyzed the slides. RESULTS: Analysis of COX-1 protein expression revealed homogenous staining in glial cells in all regions of the cervical spinal cord examined. There was no difference in expression between the control and surgical groups. However, whereas the control group demonstrated minimal COX-2 expression, the surgical group showed extensive neuronal and glial cell cytoplasmic COX-2 expression. CONCLUSIONS: This study demonstrates that surgery induces COX-2 expression in the rat cervical spinal cord. This could provide a scientific rationale for the use of selective COX-2 inhibitors as analgesics in the postoperative period.

A comparison of the Glidescope, Pentax AWS, and Macintosh laryngoscopes when used by novice personnel: a manikin study.

PURPOSE: Direct laryngoscopic tracheal intubation is a potentially lifesaving procedure, but a difficult skill to acquire and maintain. The consequences of poorly performed intubation attempts are potentially severe. The Pentax AWS and the Glidescope are indirect laryngoscopes that may require less skill to use. We therefore hypothesized that AWS and Glidescope would prove superior to the Macintosh laryngoscope when used by novices in the normal and simulated difficult airway. METHODS: In this prospective randomized crossover trial following standardized didactic instruction, medical students with no prior experience of laryngoscopy performed tracheal intubation using each device. Each student was allowed up to three attempts to intubate in a Laerdal Intubation Trainer in two laryngoscopy scenarios and in a Laerdal SimMan manikin in one scenario. The students then performed tracheal intubation of the normal airway a second time to characterize the learning curve for each device. RESULTS: The Pentax AWS provided better intubation conditions than the Glidescope or the Macintosh, resulting in greater success of intubation, particularly in the difficult laryngoscopy scenarios. The Glidescope demonstrated advantages over the Macintosh, particularly in the more difficult scenarios. Both the AWS and the Glidescope decreased the duration of intubation attempts, reduced the number of maneuvers required, and reduced the potential for dental trauma. In direct comparisons, the AWS provided the best intubation conditions. CONCLUSIONS: The Pentax AWS appears to constitute a better alternative to the Macintosh for novice personnel to acquire the skills of tracheal intubation.

Comparison of the Airtraq and Truview laryngoscopes to the Macintosh laryngoscope for use by Advanced Paramedics in easy and simulated difficult intubation in manikins.

BACKGROUND: Paramedics are frequently required to perform tracheal intubation, a potentially life-saving manoeuvre in severely ill patients, in the prehospital setting. However, direct laryngoscopy is often more difficult in this environment, and failed tracheal intubation constitutes an important cause of morbidity. Novel indirect laryngoscopes, such as the Airtraq and Truview laryngoscopes may reduce this risk. METHODS: We compared the efficacy of these devices to the Macintosh laryngoscope when used by 21 Paramedics proficient in direct laryngoscopy, in a randomized, controlled, manikin study. Following brief didactic instruction with the Airtraq and Truview laryngoscopes, each participant took turns performing laryngoscopy and intubation with each device, in an easy intubation scenario and following placement of a hard cervical collar, in a SimMan manikin. RESULTS: The Airtraq reduced the number of optimization manoeuvres and reduced the potential for dental trauma when compared to the Macintosh, in both the normal and simulated difficult intubation scenarios. In contrast, the Truview increased the duration of intubation attempts, and required a greater number of optimization manoeuvres, compared to both the Macintosh and Airtraq devices. CONCLUSION: The Airtraq laryngoscope performed more favourably than the Macintosh and Truview devices when used by Paramedics in this manikin study. Further studies are required to extend these findings to the clinical setting.

Endotracheal intubation in patients with cervical spine immobilization: a comparison of macintosh and airtraq laryngoscopes.

BACKGROUND: The Airtraq laryngoscope (Prodol Ltd., Vizcaya, Spain) is a novel single-use tracheal intubation device. The authors compared ease of intubation with the Airtraq and Macintosh laryngoscopes in patients with cervical spine immobilization in a randomized, controlled clinical trial. METHODS: Forty consenting patients presenting for surgery requiring tracheal intubation were randomly assigned to undergo intubation using a Macintosh (n = 20) or Airtraq (n = 20) laryngoscope. All patients were intubated by one of four anesthesiologists experienced in the use of both laryngoscopes. RESULTS: No significant differences in demographic or airway variables were observed between the groups. All but one patient, in the Macintosh group, were successfully intubated on the first attempt. The Airtraq reduced the duration of intubation attempts (mean +/- SD: 13.2 +/- 5.5 vs. 20.3 +/- 12.2 s), the need for additional maneuvers, and the intubation difficulty scale score (0.1 +/- 0.5 vs. 2.7 +/- 2.5). Tracheal intubation with the Airtraq caused fewer alterations in blood pressure and heart rate. CONCLUSIONS: These findings demonstrate the utility of the Airtraq laryngoscope for tracheal intubation in patients with cervical spine immobilization.

Tracheal intubation by inexperienced medical residents using the Airtraq and Macintosh laryngoscopes--a manikin study.

The Airtraq laryngoscope is a novel intubation device that may possess advantages over conventional direct laryngoscopes for use by personnel that are infrequently required to perform tracheal intubation. We conducted a prospective study in 20 medical residents with little prior airway management experience. After brief didactic instruction, each participant took turns performing laryngoscopy and intubation using the Macintosh (Welch Allyn, Welch Allyn, NY) and Airtraq (Prodol Ltd. Vizcaya, Spain) devices, in 3 laryngoscopy scenarios in a Laerdal Intubation Trainer (Laerdal, Stavanger, Norway) and 1 scenario in a Laerdal SimMan manikin (Laerdal, Kent, UK). They then performed tracheal intubation of the normal airway a second time to characterize the learning curve. In all scenarios tested, the Airtraq decreased the duration of intubation attempts, reduced the number of optimization maneuvers required, and reduced the potential for dental trauma. The residents found the Airtraq easier to use in all scenarios compared with the Macintosh laryngoscope. The Airtraq may constitute a superior device for use by personnel infrequently required to perform tracheal intubation.