Inflation Pressures for Ex Vivo Lung Biopsies After Application of Graduated Compression Staples

Short-term outcomes of dogs and cats undergoing lung lobectomy using either a self-ligating loop or a thoracoabdominal stapler

OBJECTIVE

To assess clinical outcomes of lung lobectomies in dogs and cats using either self-ligating loops (SLLs) or thoracoabdominal (TA) staplers, aiming to inform sample size calculations for future superiority trials.

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 72 dogs and 15 cats.

METHODS

Records from January 2003 to October 2023 at a single institution were reviewed. Cases with lung lobectomy performed via TA stapler or SLL with a minimum 14-day postoperative follow-up were included. Pre-, intra-, and postoperative data were collected, with outcomes of interest including the frequency of intra- and postoperative complications. Outcome comparisons between techniques were performed to inform sample size calculations.

RESULTS

A total of 101 lung lobectomies were performed. The TA stapler was used in 83 (82.2%) and the SLL in 18 (17.8%) lung lobectomies. Intraoperative complications were identified in 14/101 lung lobectomies (13.9%), including intraoperative hemorrhage in 12/101 lobectomies (11.8%) and air leakage in 2/101 lobectomies (1.9%). Postoperative complications were identified in 12/87 cases (13.8%), including 4 (4.6%) catastrophic complications and 5 (5.8%) major complications. All intra- and postoperative complications occurred in cases having undergone stapled lung lobectomy; however, no differences were identified between surgical technique and either intraoperative (p = .069) or postoperative complications (p = .112). A sample size of 103 lobectomies per technique group would be required for appropriate evaluation.

CONCLUSION

Lung lobectomy using either surgical technique provided a good short-term outcome in this population.

CLINICAL SIGNIFICANCE

Self-ligating loop lung lobectomy provided a comparable alternative to stapled lung lobectomy. Further studies are needed to assess technique superiority.

Augmenting Veterinary Minimally Invasive Surgery: Evidence-based Review of Foundational and Novel Devices and Technology

Veterinary minimally invasive surgery continues to grow as a specialty. With increasing experience in this field, comes improved accessibility as well as progressive complexity of procedures performed. Advancement in technology has been both a response to the growth and a necessary driver of continued refinement of this field. Innovative research leading to advancements in surgical equipment has led to the development of novel image acquisition platforms, cannulas, smoke evacuation systems, antifog devices, instrumentation, and ligating/hemostatic devices. These innovations will be reviewed and potential clinical applications are discussed.

Comparison of Different Pneumorrhaphy Methods after Partial Pulmonary Lobectomy in Dogs

Pulmonary loborraphy can be performed using manual sutures and staples, although other methods, such as tissue adhesives, are also cited in the veterinary literature. Although the surgery is well tolerated in the canine species, failure in pulmonary aerostasis is still a reality since all the methods described so far eventually lead to air leakage after the use of the partial lobectomy technique in the lungs. Within this context, the aim of this research was to compare the effectiveness of different hermetic sealing methods after partial lobectomy of the right caudal lung lobe (RCLL) in dogs. 30 cadavers models were divided in 6 groups: G1-cobbler suture associated with simple continuous; G2-overlapping continuous suture associated with simple continuous suture; G3-Ford interlocking suture; G4-Stapling device; G5-Tissue glue (cyanoacrylate). After performing the sealing techniques, the lungs were submerged in water and inflated with oxygen at positive ventilatory pressures at physiological (up to 14.7 mmHg, which is equivalent to up to 20 cmH2O) and supraphysiological levels (above 14.7 mmHg) to evaluate the performance of the sealing methods. At physiological ventilatory pressure levels, there was no difference between groups. Sealing with surgical glue was superior to interlocking sutures and stapling devices at supraphysiological levels of ventilatory pressure.

Air leaks: Stapling affects porcine lungs biomechanics

During thoracic operations, surgical staplers resect cancerous tumors and seal the spared lung. However, post-operative air leaks are undesirable clinical consequences: staple legs wound lung tissue. Subsequent to this trauma, air leaks from lung tissue into the pleural space. This affects the lung's physiology and patients' recovery. The objective is to biomechanically and visually characterize porcine lung tissue with and without staples in order to gain knowledge on air leakage following pulmonary resection. Therefore, a syringe pump filled with air inflates and deflates eleven porcine lungs cyclically without exceeding 10 cmH₂O of pressure. Cameras capture stereo-images of the deformed lung surface at regular intervals while a microcontroller simultaneously records the alveolar pressure and the volume of air pumped. The raw images are then used to compute tri-dimensional displacements and strains with the Digital Image Correlation method (DIC). Air bubbles originated at staple holes of inner row from exposed porcine lung tissue due to torn pleural on costal surface. Compared during inflation, left upper or lower lobe resections have similar compliance (slope of the pressure vs volume curve), which are 9% lower than healthy lung compliance. However, lower lobes statistically burst at lower pressures than upper lobes (p-value<0.046) in ex vivo conditions confirming previous clinical in vivo studies. In parallel, the lung deformed mostly in the vicinity of staple holes and presented maximum shear strain near the observed leak location. To conclude, a novel technique DIC provided concrete evidence of the post-operative air leaks biomechanics. Further studies could investigate causal relationships between the mechanical parameters and the development of an air leak.

Minimizing the Risk of Aerosol Contamination During Elective Lung Resection Surgery

BACKGROUND

In the setting of the COVID-19 pandemic, the conduct of elective cancer surgery has become an issue because of the need to balance the requirement to treat patients with the possibility of transmission of the virus by asymptomatic carriers. A particular concern is the potential for viral transmission by way of aerosol which may be generated during perioperative care. There are currently no guidelines for the conduct of elective lung resection surgery in this context.

METHODS

A working group composed of 1 thoracic surgeon, 2 anesthesiologists and 1 critical care specialist assessed the risk for aerosol during lung resection surgery and proposed steps for mitigation. After external review, a final draft was approved by the Committee for the Governance of Perioperative and Surgical Activities of the Hôpital Maisonneuve-Rosemont, in Montreal, Canada.

RESULTS

The working group divided the risk for aerosol into 6 time-points: (1) intubation and extubation; (2) Lung isolation and patient positioning; (3) access to the chest; (4) conduct of the surgical procedure; (5) procedure termination and lung re-expansion; (6) chest drainage. Mitigating strategies were proposed for each time-point.

CONCLUSIONS

The situation with COVID-19 is an opportunity to re-evaluate operating room protocols both for the purposes of this pandemic and similar situations in the future. In the context of lung resection surgery, specific time points during the procedure seem to pose specific risks for the genesis of aerosol and thus should be the focus of attention.

Evaluation of a pre-tied ligature loop for canine total lung lobectomy

OBJECTIVE

To determine the ability of a pre-tied ligature loop (PLL) to create a seal against physiological airway pressures after total lung lobectomy and report outcomes in dogs requiring lung lobectomy.

STUDY DESIGN

Ex vivo experimental randomized study and clinical case study.

SAMPLE POPULATION

Thirty cadaveric canine lung lobes and 5 client-owned dogs.

METHODS

Thirty canine lung lobes from dogs weighing 22.5-35 kg were randomized to lobectomy with stapler, PLL, or suture ligation. After lobectomy, each bronchial stump was submerged in water, and the mainstem airway pressure was increased to 80 mm Hg. Leakage was compared between techniques. The PLL was subsequently used in 5 dogs (17-25 kg) with neoplastic disease requiring total lung lobectomy.

RESULTS

Two stapled and 4 sutured bronchial stumps leaked at supraphysiological pressures >15 mm Hg. One stapled bronchial stump failed at a physiological airway pressure (5 mm Hg). None of the PLL lobectomies leaked. The incidence of bronchial stump failures did not differ among techniques (P = .15). Lung lobectomy was performed successfully with the PLL in 5 clinical cases with no intraoperative or postoperative complications; median follow-up time was 6 months.

CONCLUSION

Bronchial ligation with the PLL reliably resisted physiological airway pressures and performed comparably to current standard techniques in cadavers. The PLL provided an adequate air and vascular seal in 5 clinical cases undergoing total lung lobectomy.

CLINICAL RELEVANCE

Pre-tied ligature loops provide an alternative method for total lung lobectomy in dogs.

Preclinical quantification of air leaks in a physiologic lung model: effects of ventilation modality and staple design

Purpose

Thoracic air leaks are a common complication following pulmonary resections. Limitations in clinical studies and preclinical models have hindered efforts to understand the pathophysiology of air leaks. With an emphasis on staple-line specific air leaks, we hypothesize that ventilation modality – intraoperative positive pressure vs postoperative negative pressure – and stapler design may play a role in air leaks.

Methods

Using a novel physiologic lung model, air leaks associated with graduated and uniform staple designs were evaluated under positive and negative pressure ventilation, simulating perioperative breathing in porcine lungs. Air leak incidence, air leak volume, and air leak rate were captured along with ventilation pressure and tidal volume.

Results

In all cases, negative pressure ventilation was associated with a higher occurrence of leaks when compared to positive pressure ventilation. Lungs leaked more air and at a faster rate under negative pressure ventilation compared to positive pressure ventilation. Graduated staple designs were associated with higher occurrence of leaks as well as larger leak rates when compared to uniform staples. Tissue thickness was not associated with differences in air leaks when tested with appropriate staple heights.

Conclusion

Using a novel lung model to investigate the pathophysiology of air leaks, we have identified breathing modality and staple design as two important variables that may impact air leaks. This work will help guide device design and drive future studies in human tissue, and it may help inform clinical practice to ultimately improve patient outcomes.