One-lung versus two-lung ventilation in the closed-chest anesthetized dog: a comparison of cardiopulmonary parameters

Complications and outcomes of thoracoscopic-assisted lung lobectomy in dogs

OBJECTIVE

To describe complications and outcomes of dogs undergoing thoracoscopic-assisted (TA) lung lobectomy.

STUDY DESIGN

Multi-institutional, retrospective study.

ANIMALS

Client-owned dogs (n = 30).

METHODS

Medical records of dogs that underwent TA lung lobectomy were reviewed. Signalment, bodyweight, clinical signs, imaging findings, surgical variables, complications, and short-term/long-term outcome were assessed. Thoracoscopic-assisted lung lobectomy was performed with a mini-thoracotomy.

RESULTS

Twelve intraoperative complications were recorded in 11 dogs, 6 requiring conversion to open thoracotomy. Reasons for conversion were reported in 5/6 dogs and included adhesions (2), difficultly manipulating the lesion through the mini-thoracotomy (2), and acute oxygen desaturation (1). One lung ventilation was successful in 4 of the 7 dogs in which this was attempted. A linear stapling device (DST series Medtronic, Minneapolis, Minnesota) was used for lung lobe ligation in 14 dogs. Twenty-three dogs underwent surgery for a neoplastic lesion, with 19 of these being carcinoma. The median lesion size was 4.3 cm (range 1-10 cm); margins were clean, except in 1 dog. Complications were documented in 8 dogs prior to discharge, 5 of these being classified as mild. Twenty-nine dogs were discharged at a median of 47 h postoperatively (range 24-120 h). Death was reported in 9 dogs, with a median survival time of 168 days (range 70-868 days).

CONCLUSION

Thoracoscopic-assisted lung lobectomy was achieved with few major complications in the population reported here. Dogs were able to be discharged from hospital quickly, with most surviving beyond the follow-up period.

CLINICAL SIGNIFICANCE

Thoracoscopic-assisted lung lobectomy may be considered to facilitate the excision of larger pulmonary lesions or to treat smaller dogs, in which a thoracoscopic excision may be technically more challenging.

Thoracoscopic treatment of persistent right aortic arch in dogs with and without one lung ventilation

OBJECTIVE

To evaluate thoracoscopic treatment of persistent right aortic arch (PRAA) in dogs with and without the use of one lung ventilation (OLV).

STUDY DESIGN

Retrospective cohort study.

ANIMALS

Twenty-two (client-owned and shelter) dogs diagnosed with PRAA.

METHODS

Medical records were reviewed retrospectively and intraoperative and immediate postoperative data were compared between dogs that underwent thoracoscopic treatment of PRAA with (OLV+) and without (OLV-) OLV.

RESULTS

Ten of the 12 dogs in the OLV+ group and 7/10 dogs in the OLV- group had their left ligamentum arteriosum successfully ligated during thoracoscopy. Median surgical time, surgery complications, anesthesia complications, and rate of conversion to an open thoracotomy due to limited visualization or surgical complications were similar between the two groups.

CONCLUSION

Thoracoscopic treatment of PRAA can be performed with or without OLV. Surgical time, intraoperative complications, and conversion rates were similar between dogs that underwent thoracoscopic treatment of PRAA with and without OLV. OLV may not have contributed to improved visualization in this group of dogs.

CLINICAL SIGNIFICANCE (OR IMPACT)

The use of OLV is safe during thoracoscopic treatment of PRAA. OLV did not appear to provide significant benefits in this case series and thoracoscopic treatment of PRAA in dogs may be performed successfully with or without the use of OLV.

One-lung ventilation with use of a double lumen tube in two dogs; when right might be wrong

One-lung ventilation (OLV) is an anaesthetic technique utilised for improved visualisation and access of the surgical field during thoracoscopy. The authors present two cases that underwent OLV with use of a double lumen tube (DLT). The first case was intubated with endoscopic guidance for bronchial port intubation of the right mainstem bronchus. This dog experienced prolonged periods of intraoperative hypoxemia. Upon case review, it was suspected intubation of the mainstem bronchus resulted in occlusion of the right cranial lung lobe. In the second case, the DLT was placed bronchoscopically into the left mainstem bronchus with the aid of computed tomography (CT). Excellent intraoperative oxygenation was achieved. When DLTs are used in dogs, their anatomical differences from humans make them susceptible to additional lung occlusion and pulmonary shunting. Computed tomography is recommended as a fundamental addition to bronchoscopy for correct tube placement.

Comparison of the effects of isoflurane versus propofol-remifentanil anesthesia on oxygen delivery during thoracoscopic lung lobectomy with one-lung ventilation in dogs

This study compared effects of isoflurane inhalation (ISO) and propofol-remifentanil combined total intravenous anesthesia (TIVA) on oxygenation during thoracoscopic lung lobectomy with 30-min one-lung ventilation (1LV). Thoracoscopic right middle lung lobectomy was performed in ten dogs divided into ISO and TIVA groups, and cardiopulmonary parameters were measured with blood gas analysis. Throughout the study, isoflurane was inhaled up to 1.5%, and the infusion rates of propofol and remifentanil were 0.2 to 0.4 mg/kg/min and 6 to 11 µg/kg/h, respectively. Cardiac index was not affected in the ISO group, but it increased during 1LV in the TIVA group. There were significant alterations in arterial oxygen pressure, arterial oxygen saturation, oxygen content, and shunt fraction associated with 1LV in each group. However, oxygen delivery did not decrease significantly due to open chest condition, 1LV, or surgical maneuver in either group, rather it increased during 1LV in the TIVA group. All parameters showed no significant difference between groups. Pulmonary vascular resistant index was unaffected in both groups, and there was no difference between groups except in re-ventilation phase. Accordingly, the effect of both anesthetic regimens on oxygenation was not different between groups and can be used with short-term 1LV for thoracoscopic lung lobectomy in dogs.

A comparison between two lung ventilation with CO2 artificial pneumothorax and one lung ventilation during thoracic phase of minimally invasive esophagectomy

Background

To investigate the feasibility and safety of two lung ventilation with artificial pneumothorax in minimally invasive esophagectomy (MIE) through a comparison with conventional one lung ventilation.

Methods

Eleven hundred and sixty-six patients with esophageal cancer, who underwent McKeown MIE in our center from February 2006 to December 2016, were studied retrospectively. Seven hundred and five patients who underwent one lung ventilation with double lumen endotracheal tube (DLET) were assigned to DLET group. Other 461 patients who underwent two lung ventilation with single lumen endotracheal tube (SLET) were assigned to SLET group. Clinical characteristics, surgical variables and complications were compared between two groups.

Results

There were comparable patient characteristics in two groups. Surgical variables and complications were discussed between two groups. SLET group seemed to have shorter operative time, shorter postoperative hospital stay, and more harvested recurrent laryngeal nerve (RLN) lymph nodes than DLET group, which might be attributed to experienced surgeons. However, there were no significant differences of complications between two groups. Intraoperative clinical parameters were further studied. Before intubation and artificial pneumothorax, there were no significant differences between two groups, except diastolic blood pressure (DBP). With the application of artificial pneumothorax, patients in SLET group have obviously higher PO₂, PCO₂, and PetCO₂ value, and slightly lower pH value and blood pressure during thoracic phase. After the thoracic phase, the changes induced by artificial pneumothorax in SLET group were gradually reversed and clinical parameters gradually return to normal level.

Conclusions

Two lung ventilation with artificial pneumothorax is a safe and feasible choice during MIE.

Complications and Conversion from Endoscopic to Open Surgery

Endoscopic surgery is a rapidly expanding modality of diagnosis and treatment of small animal patients. The development of skills, equipment, and minimally invasive means of correcting complications may be of great importance in decreasing the incidence of conversion from endoscopic to open surgery; however, conversion to an open approach should never be seen as a failure. Conversion should be considered at any time that it is of the greatest benefit for the patient. This concept is important enough to warrant discussion with the owner before surgery and acceptance of the need to convert without further consultation during the procedure.

Thoracoscopy in the cat: an up-and-coming diagnostic and therapeutic procedure

PRACTICAL RELEVANCE

Thoracoscopy provides a minimally invasive means of diagnosis and offers many important benefits when compared with open thoracotomy.

CLINICAL CHALLENGES

The expense of the equipment, the steep learning curve required to gain proficiency in thoracoscopic surgery, and the limitations imposed by the feline thoracic cavity, in terms of working and viewing space, are some of the challenges that have limited its uptake to date. However, it is envisaged that it will increase as a technique in feline medicine, in much the same way as laparoscopy has.

AUDIENCE

This article is directed at veterinarians currently performing open thoracic surgery and the associated aftercare who concurrently are adept at endoscopic surgery.

EVIDENCE BASE

The article draws on the small body of literature that is available on thoracoscopy in cats, which includes reports of its use for evaluation and management of undiagnosed pleural effusion, lung lobe torsion, persistent right aortic arch and chylothorax.

Anesthesia for endoscopy in small animals

This article discusses considerations for general anesthesia for various endoscopic procedures in small animals. Specific drug and monitoring recommendations are made. Special physiologic concerns of individual procedures affecting the anesthetized patient are discussed.

Theoretical and practical aspects of anaesthesia for thoracic surgery

Thoracic surgical procedures account for only a small fraction of all surgery undertaken in the NHS. Thoracic surgery is performed in specialist centres as patients often suffer serious co-morbidities and require vigilant care and observation by staff involved in their treatment. Anaesthesia for thoracic surgery challenges the theoretical and practical experience of all involved. This review briefly summarises the anaesthetic skills and knowledge required to deliver a safe and professional service to patients with thoracic pathology.

Effect of Positive End-Expiratory Pressure on Oxygen Delivery During 1-Lung Ventilation for Thoracoscopy in Normal Dogs

OBJECTIVE

To evaluate the effect of positive end-expiratory pressure (PEEP) on oxygen delivery (DO(2)) with 1-lung ventilation during thoracoscopy in normal anesthetized dogs.

STUDY DESIGN

Prospective, controlled experimental study.

ANIMALS

Eight, adult, intact Walker Hound dogs weighing 25.6-29.2 kg.

METHODS

Anesthetized dogs had 1-lung ventilation during an open-chest condition. A Swan-Ganz catheter was used to measure pulmonary hemodynamic variables and to obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was used for measurement of systemic arterial pressure and to obtain arterial blood samples for blood gas analysis. Oxygen delivery was calculated and used to assess the effect of 0, 2.5, and 5 cm H(2)O PEEP during 1-lung ventilation on cardiopulmonary function. Each dog was its own control at 0 cm H(2)O PEEP. A randomized block ANOVA for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary variables.

RESULTS

Use of 5 cm H(2)O PEEP induced a significant augmentation in the arterial partial pressure of oxygen (PaO(2)). Shunt fraction (Q(s)/Q(t)), physiologic dead space (V(D)/V(T)), and the alveolar-arterial oxygen difference (P(A-a)O(2)) decreased significantly after 5 cm H(2)O PEEP, compared with 1-lung ventilation without PEEP. Use of 2.5 cm H(2)O PEEP had no significant effect on cardiopulmonary variables. Use of PEEP had no significant effect on arterial oxygen saturation (SaO(2)), DO(2), and hemodynamic variables in normal dogs.

CONCLUSIONS

PEEP had no effect on DO(2) in normal dogs undergoing open-chest 1-lung ventilation because it had no adverse effect on hemodynamic variables.

CLINICAL RELEVANCE

PEEP in normal dogs during open-chest 1-lung ventilation for thoracoscopy is not detrimental to cardiac output and can be recommended in clinical patients.

Accidental entrapment of an endo-bronchial blocker tip by a surgical stapler during selective ventilation for lung lobectomy in a dog

OBJECTIVE

To describe the use of an endobronchial blocker (EBB) and to perform selective ventilation during pulmonary lobe resection via thoracotomy in a dog and report its accidental stapling in the resection site.

STUDY DESIGN

Clinical case report.

ANIMAL

One female dog with a suspected abscess or neoplasia of the right caudal pulmonary lobe.

METHODS

One-lung ventilation was performed using a wire-guided EBB to seal the contaminated parenchyma and facilitate surgical access. The affected lung parenchyma was resected and the resection site was closed with staples.

RESULTS

Lobar resection was performed successfully, but the loop of the EBB guide wire was inadvertently entrapped in the staple line of the lobectomy. Staples were removed to release the wire loop, and the resulting air leak caused loss of ventilation control until the parenchyma was re-sealed.

CONCLUSIONS

We recommend removing the wire guide associate with the EBB after successful lung separation to avoid accidents that could have life-threatening consequences if not recognized.

CLINICAL RELEVANCE

One-lung ventilation is useful to isolate healthy parenchyma from diseased parenchyma during lobectomy. Anesthesiologists and surgeons need to be aware of the potential complications associated with use of EBB.

Unstable endobronchial intubation in a cat undergoing tracheal laceration repair

A peri-carinal tracheal laceration was produced in a 11-year-old cat during tracheal intubation. Before reconstructive surgery began, the leak was bypassed with an endobronchial tube positioned using endoscopy and direct vision. However, single-lung ventilation could not be sustained because the tube became dislodged and could not be repositioned. Consequently, surgery was completed with periods of intermittent apnoea interspersed with manually controlled hyperventilation. Cardiovascular variables were stable during anaesthesia and no signs of hypoxia were detected. The difficulties in maintaining endobronchial tube position resulted from the animal's small size relative to the dimensions of the endotracheal tube.

Cardiopulmonary effects of thoracoscopy in anesthetized normal dogs

OBJECTIVE

To evaluate the effect of an open-chest condition on oxygen delivery in anesthetized dogs.

STUDY DESIGN

Prospective, controlled experimental study.

ANIMALS

Eight clinically normal adult Walker Hound dogs weighing 25.6-29.2 kg.

METHODS

Eight anesthetized dogs underwent an open-chest operation after the insertion of thoracoscopy cannulae in the lateral chest walls. A Swan Ganz catheter was used to both measure hemodynamic parameters and obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was placed to both measure arterial blood pressure and obtain blood samples for blood gas analysis. Oxygen delivery index and oxygen extraction ratio were calculated. A randomized block anova for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary parameters.

RESULTS

Creation of an open chest did not significantly affect oxygen delivery index (DO(2)I; p = 0.545). It induced a significant decrease in arterial oxygen partial pressure (PaO(2); p = 0.018) and arterial oxygen content (CaO(2); p = 0.025). It induced a significant increase in shunt fraction (p = 0.023), physiologic dead space (p = 0.015), and alveolar-arterial oxygen difference (p = 0.019). Arterial partial pressure of carbon dioxide (PaCO(2); p = 0.766) and arterial hemoglobin oxygen saturation (SaO(2); p = 0.178) were not significantly affected. Diastolic (DPAP; p = 0.050) and mean (MPAP; p = 0.033) pulmonary arterial pressures were significantly increased by opening the chest. Other hemodynamic parameters were not significantly affected.

CONCLUSIONS

Opening the thoracic cavity is not detrimental to hemodynamic function and oxygen delivery in normal dogs, although impaired gas exchange does occur.

CLINICAL RELEVANCE

Close monitoring of patients is recommended during open-chest thoracoscopy as adverse effects on gas exchange can contribute to hypoxemia.

Thoracoscopic treatment of bullous emphysema in 3 dogs

OBJECTIVE

To report thorascopic partial lobectomy for treatment of bullous emphysema in dogs.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Three dogs with spontaneous pneumothorax.

METHODS

Thoracoscopy without pulmonary exclusion was used to identify bulla. The thorascope was introduced into the thorax lateral to the xyphoid process, and instrument portals were made at different levels along the thoracic wall between the third and tenth intercostal spaces. The thorascope was passed through the mediastinum to view the opposite pleural cavity. After identification of bullae, the affected lung was excised using an endoscopic stapler, and the incision line was checked for air leakage. Thoracic drains were used for air aspiration for 2 days after surgery.

RESULTS

Bullae were confirmed histologically as emphysematous lesions. Lung inflation did not interfere with identification of bullae or with surgery. All dogs had full recovery without recurrence for 18 to 29 months after surgery.

CONCLUSIONS

Identification and ablation of bulla can be performed thoracoscopically without pulmonary exclusion in dogs.

CLINICAL RELEVANCE

Thoracoscopy offers several advantages compared with thoracotomy for treatment and diagnosis of idiopathic pneumothorax, including ease of identification of bullae and reduced postoperative pain and morbidity.

Effect of one-lung ventilation on oxygen delivery in anesthetized dogs with an open thoracic cavity

OBJECTIVE

To evaluate effects of one-lung ventilation on oxygen delivery in anesthetized dogs with an open thoracic cavity.

ANIMALS

8 clinically normal adult Walker Hound dogs.

PROCEDURE

Each dog was anesthetized and subjected to one-lung ventilation during a period when it had an open thoracic cavity. A Swan-Ganz catheter was used to measure hemodynamic variables and obtain mixed-venous blood samples. A catheter was inserted in the dorsal pedal artery to measure arterial pressure and obtain arterial blood samples. Oxygen delivery index was calculated and used to assess effects of one-lung ventilation on cardiopulmonary function. Effects on hemodynamic and pulmonary variables were analyzed.

RESULTS

One-lung ventilation caused significant decreases in PaO2, arterial oxygen saturation (SaO2), mixed-venous oxygen saturation, and arterial oxygen content (CaO2). One-lung ventilation caused significant increases in PaCO2, physiologic dead space, and alveolar-arterial oxygen difference. Changes in SaO2, CaO2, and PaCO2, although significantly different, were not considered to be of clinical importance. One-lung ventilation induced a significant increase in pulmonary arterial wedge pressure, mean pulmonary artery pressure, and shunt fraction. One-lung ventilation did not have a significant effect on cardiac index, systemic vascular resistance index, pulmonary vascular resistance index, and oxygen delivery index.

CONCLUSIONS AND CLINICAL RELEVANCE

One-lung ventilation affected gas exchange and hemodynamic function, although oxygen delivery in clinically normal dogs was not affected during a period with an open thoracic cavity. One-lung ventilation can be used safely in healthy dogs with an open thoracic cavity during surgery.

Cardiopulmonary effects of intrathoracic insufflation in dogs

This study was designed to quantify the effects of incremental positive insufflation of the intrathoracic space on cardiac output (CO), heart rate (HR), arterial pressure (AP), central venous pressure (CVP), and percent saturation of hemoglobin with oxygen (SPO2) in anesthetized dogs. Seven healthy, adult dogs from terminal teaching laboratories were maintained under anesthesia with isoflurane delivered with a mechanical ventilator. The experimental variables were recorded before introduction of an intrathoracic catheter, at intrathoracic pressures (IP) of 0 mm Hg, 3 mm Hg insufflation, and additional increments of 1 mm Hg insufflation thereafter until the SPO2 remained <85% despite increases in minute volume. Finally the variables were measured again at 0 mm Hg IP. The cardiac output and systolic and diastolic AP significantly (P < 0.05) decreased at 3 mm Hg IP. Significant decreases in SPO2 were seen at 10 mm Hg IP. Significant increase in CVP was noted at 6 mm Hg IP. Heart rate decreased significantly at 5 to 6 mm Hg IP but was not decreased above 6 mm Hg IP. Given the degree of CO decrease at low intrathoracic pressures, insufflation-aided thoracoscopy should be used with caution and at the lowest possible insufflation pressure. Standard anesthetic monitoring variables such as HR and AP measurements may not accurately reflect the animal's cardiovascular status.

Surgical and nonsurgical management of and selected risk factors for spontaneous pneumothorax in dogs: 64 cases (1986-1999)

OBJECTIVE

To compare results of surgical versus nonsurgical treatment of spontaneous pneumothorax in dogs.

DESIGN

Retrospective study.

ANIMALS

64 dogs with pneumothorax without any history of antecedent trauma.

PROCEDURE

Information on signalment, thoracic radiographic findings, treatment, histologic findings, and outcome was obtained from the medical records. Signalment of affected dogs was compared with signalment of a control population of 260 dogs examined by the emergency service for reasons other than pneumothorax during the study period.

RESULTS

Siberian Huskies were overrepresented in the case population, compared with the control population of dogs examined by the emergency service for other reasons. Twenty-eight dogs were treated without surgery (ie, thoracocentesis or tube thoracostomy with or without cage rest), and 36 were treated with surgery. Information regarding final outcome was available for 33 dogs treated with surgery (median follow-up time, 485 days) and 15 dogs treated without surgery (median follow-up time, 366 days). Dogs that underwent surgery had significantly lower recurrence (1/30) and mortality (4/33) rates, compared with dogs treated without surgery (6/12 and 8/15, respectively). A definitive diagnosis was obtained for 38 dogs, including 34 of 36 dogs undergoing surgery; 26 had bullous emphysema and 4 had neoplasia. Two dogs developed spontaneous pneumothorax secondary to migration of plant foreign bodies.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that recurrence and mortality rates for dogs with spontaneous pneumothorax managed surgically were significantly lower than rates for dogs managed by nonsurgical means alone. Early surgical intervention is recommended for definitive diagnosis and treatment of dogs with spontaneous pneumothorax.

The effects of intrathoracic pressure during continuous two-lung ventilation for thoracoscopy on the cardiorespiratory parameters in sevoflurane anaesthetized dogs

The cardiopulmonary effects of different levels of carbon dioxide insufflation (3, 5 and 2 mm Hg) under two-lung ventilation were studied in six sevoflurane (1.5 minimum alveolar concentration; MAC) anaesthetized dogs during left-sided thoracoscopy. An arterial catheter, Swan-Ganz catheter and multianaesthetic gas analyser were used to monitor the cardiopulmonary parameters during the experiment. Baseline data were obtained before intrathoracic pressure elevation and the measurements were repeated at intervals after left lung collapse induced by insufflation with carbon dioxide gas. The intrapleural pressure levels used were 3, 5 and 2 mm Hg. Arterial blood pressures, cardiac index, stroke index, left and right ventricular stroke work index, arterial haemoglobin saturation, arterial oxygen tension and systemic vascular resistance decreased significantly during hemithorax insufflation, whereas heart rate, right atrial pressure, mean, systolic and diastolic pulmonary arterial pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance and arterial carbon dioxide tension significantly increased during intrapleural pressure elevation. Although carbon dioxide insufflation into the left hemithorax with an intrapleural pressure of 2-5 mm Hg compromises cardiac functioning in 1.5 MAC sevoflurane anaesthetized dogs, it can be an efficacious adjunct for thoracoscopic procedures. Intrathoracic view was satisfactory with an intrapleural pressure of 2 mm Hg. Therefore, the intrathoracic pressure rise during thoracoscopy with two-lung ventilation should be kept as low as possible. Additional insufflation periods should be avoided, since a more rapid and more severe cardiopulmonary depression can occur.

Video-assisted thoracoscopy

Thoracoscopy is a minimally invasive operative endoscopic procedure designed for visual inspection of the thoracic cavity. The use of small, highly maneuverable, rigid telescopes allows visualization beyond what is possible by standard operative techniques. The use of a small video camera attached to a standard rigid telescope allows the operator and assistants to view a simultaneous, enlarged, and clear image. This article focuses on the basic diagnostic and surgical techniques used in veterinary video-assisted thoracoscopy.