Case 6-5-1992 Anesthetic considerations for thoracoscopic procedures

Anaesthetic implications of paediatric thoracoscopy

Anaesthetic care during thoracic surgical procedures in children combines components of the knowledge bases of paediatric anaesthesia with those of thoracic anaesthesia. This article highlights the principles of anaesthesia during thoracoscopic surgery in children including preoperative evaluation, anaesthetic induction techniques, maintenance anaesthesia and options for postoperative analgesia. In addition, given the need to provide optimal surgical visualization during the procedure, one lung ventilation may be required. Techniques to provide one lung ventilation in the paediatric patient and the principles of anaesthesia care during one lung ventilation are discussed.

Cardiovascular changes during drainage of pericardial effusion by thoracoscopy

BACKGROUND

Cardiovascular changes during drainage of pericardial effusion are not well understood, and most studies are of systemic effects and not of right ventricular performance. Thoracoscopy is not widely used to drain pericardial effusions because of haemodynamic changes in relation to the use of single lung ventilation.

PATIENTS AND METHODS

We studied 16 patients undergoing partial pericardiectomy for pericardial effusion, using videothoracoscopy with a low-pressure pneumothorax (6 mm Hg). Cardiac output was measured by thermodilution with the patient anaesthetized in the supine position before the procedure; in the right lateral position after a low-pressure pneumothorax had been established; and after drainage of the pericardial effusion.

RESULTS

Before the procedure, cardiac output was low and central venous pressure and pulmonary artery occlusion pressure were increased. Systemic vascular resistance and arterial blood pressure were within normal limits. Cardiac filling pressure and pulmonary arterial pressure increased during the pneumothorax. After the drainage cardiac index increased and systemic and pulmonary vascular resistances were reduced.

CONCLUSIONS

Pericardial effusion reduces right ventricular distensibility, right and left systolic ventricular function, and cardiac output. Anaesthesia with mechanical ventilation and a low-pressure pneumothorax do not affect the circulation greatly. Drainage of the pericardial effusion allows cardiac distensibility to increase and cardiac performance changes to allow increased ejection.

Physiologic changes during thoracoscopy

Despite the obvious benefits of minimally invasive surgery, the physiologic changes associated with thoracoscopic procedures present multiple challenges. The lung is the site of gaseous exchange, but during thoracoscopic surgery it is simultaneously either the surgical target organ or responsible for obscuring surgical exposure. Thus, there is a conflict of interests between the need to provide ideal surgical conditions and the need to maintain normal pulmonary and cardiovascular physiology. In an attempt to minimize the physiologic insult associated with thoracoscopic surgery, multiple anesthetic and surgical techniques have therefore been developed. None are entirely problem free, however. Because the physiologic changes are technique specific, a clear understanding of the dynamic interaction between the anesthetic-surgical technique and patient physiology is essential.

Ventilation strategy for video-assisted thoracoscopic clipping of patent ductus arteriosus in children

Video-assisted endoscopic techniques have reduced operative trauma in adult thoracic and general surgery but its application in children with congenital heart disease has been limited. We report the use of video-assisted thoracoscopic (VAT) technique of clipping patent ductus arteriosus (PDA) in children. Forty patients with PDA were divided into two groups: during VAT surgery patients in group A [mean age=3.6 +/- 2.4 (SD) years] were managed with right main stem bronchial intubation and those in the group B [mean age=3.7 +/- 2.7 (SD) years] received low tidal volume-high frequency ventilation using a Siemens 900C ventilator. The mean oxygen saturation (SpO2) observed during the surgical intervention was significantly lower in group A (90%) compared to group B (96.8%) while the surgical convenience was not different. We conclude that a low tidal volume-high frequency ventilation is acceptable and safe in patients with PDA undergoing VATS.

Total intravenous anesthesia and high-frequency jet ventilation during transthoracic endoscopic sympathectomy for treatment of essential hyperhidrosis palmaris: a new approach

OBJECTIVE

To evaluate the effects of high-frequency jet ventilation (HFJV) applied to both lungs on hemodynamic parameters, oxygenation, and operating conditions during bilateral videothoracoscopic sympathectomy.

DESIGN

A prospective, unblinded study.

SETTING

An ambulatory surgical unit at a university medical center.

PARTICIPANTS

30 patients (11 men, 19 women), ASA status 1.

INTERVENTION

Bilateral videothoracoscopic sympathectomies were performed using total intravenous anesthesia with propofol, alfentanil, and atracurium, and the patients were ventilated with an oxygen-air mixture using HFJV delivered to both lungs with a Hi-Lo Jet tracheal tube (Mallinckrodt).

MEASUREMENTS AND MAIN RESULTS

Mean total anesthesia time was 55 +/- 13 minutes. Hemodynamic parameters remained stable during surgery, although ablation of the sympathetic ganglia induced three incidences of bradycardia (10% of the patients), which were responsive to atropine. Four patients developed oxygen desaturation (Sa O2 < 90%) after the creation of the pneumothorax. Surgical conditions were considered excellent by the surgeons. Concerning postoperative complications, a temporary Horner's syndrome was observed in one patient. Another patient had a mild residual pneumothorax on the first postoperative day that resolved without insertion of a chest tube.

CONCLUSIONS

It was concluded that HFJV applied to both lungs is an easy and safe anesthetic technique that provides excellent surgical conditions and causes a minor incidence of morbidity.

Positive end-expiratory pressure during one-lung ventilation improves oxygenation in patients with low arterial oxygen tensions

OBJECTIVE

The application of 10 cm H2O of positive end-expiratory pressure (PEEP10) to the ventilated lung during one-lung ventilation (OLV) has an unpredictable effect on PaO2. It was hypothesized that patients with a low PaO2 (< 80 mmHg) during OLV may benefit from application of PEEP.

DESIGN

Prospective, open.

SETTING

A university medical center.

PARTICIPANTS

Eighteen patients were studied who were undergoing OLV for pulmonary resection. All were anesthetized with thiamylal, N2O/O2 (50%/50%), isoflurane, and pancuronium.

INTERVENTIONS

Application of PEEP10 during one-lung ventilation.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and oxygenation were measured during two-lung ventilation in the lateral position, OLV, and OLV plus application of PEEP10. Overall, PEEP10 during OLV failed to produce significant changes in PaO2, Qs/Qt%, cardiac output (CO), SvO2, or mean arterial pressure. However, in 11 patients whose PaO2 was less than 80 mmHg during OLV, application of PEEP10 significantly increased PaO2, decreased Qs/Qt%, and decreased CO (p < 0.05). In the 7 patients whose PaO2 was greater than 80 mmHg on OLV, the authors did not find a significant effect of PEEP10 on the hemodynamic or oxygenation parameters measured.

CONCLUSIONS

In patients with a low PaO2 (< 80 mmHg) during OLV with F1O2 = 0.5, PaO2 is increased by the application of PEEP10. This maneuver may be useful in situations in which application of continuous positive airway pressure (CPAP) to the nonventilated lung is not possible.

Video-assisted thoracoscopic surgery in the paediatric population

OBJECTIVE

Video-assisted thoracoscopic surgery (VATS) is now widely practised in adults but there are few publications on its application in the paediatric population.

METHODOLOGY

Retrospective review of the authors' experience with VATS in children under 16 years old during an 18 month period in a university teaching hospital.

RESULTS

From September 1993 to March 1994, VATS was attempted in 14 patients. Five were unsuccessful because of pleural symphysis or inability to collapse the upper lung. Ten cases of VATS were successfully performed in the remaining nine patients (eight males, one female; age range from 22 days to 15 years old). These included two drainages and limited decortications for loculated pleural effusion, one guided drainage of pericardial effusion, one thymectomy for thymic hyperplasia, three wedge resections for metastatic pulmonary osteosarcoma and three bleb excisions and pleurodesis for primary spontaneous pneumothoraces. There were no intra-operative complications. There was one death from dysrhythmia following an uneventful wedge resection. The mean duration of chest tube drainage was 1.4 days and postoperative hospital stay 2.6 days excluding two patients who stayed for further medical treatment.

CONCLUSION

VATS is a useful approach in selected cases but further development of this approach awaits refinement of anaesthetic technique and endoscopic instrumentation.

One hundred and sixty-three consecutive video thoracoscopic procedures: the Hong Kong experience

Video-assisted thoracoscopy (VAT) offers a new approach to the diagnosis and treatment of many thoracic conditions. From September 1992 to August 1993, a total of 163 VAT procedures were successfully performed on 108 patients (87 male, 21 female; age range from 12 to 77) which consisted of 42 bleb eliminations and 64 mechanical pleurodesis for spontaneous pneumothorax, 11 wedge resections for pulmonary nodules, three wedge biopsies for diffuse pulmonary infiltrate, four thoracic sympathectomies, resections of two mediastinal masses, three pericardial windows, 10 guided pleural biopsies for undiagnosed effusions, six guided drainage of empyema and haemothorax, 16 staging of intrathoracic tumours and two explorations for penetrating thoracic trauma. There was no procedure-related mortality. Complications included one recurrence for spontaneous pneumothorax, one re-exploration for bleeding (also by VAT approach), one wound infection, and six persistent air leaks for more than 10 days. The median duration of postoperative chest tube drainage was 2 days and the median hospital stay was 4 days. It was concluded that VAT is a safe and effective approach in thoracic surgery and with further refinement in instrumentation even more procedures will be technically feasible. The long-term results of VAT are being awaited in order to define its true merits in thoracic surgery.

Hemodynamic effects of carbon dioxide insufflation during thoracoscopy

As more complex thoracoscopic procedures are performed, adequate exposure becomes increasingly more important. The insufflation of CO2 has been demonstrated to aid in the compression of lung parenchyma and the effacement of subpleural lesions, and to act as a retractor when combined with changes in patient position. However, a recent study demonstrated that CO2 insufflation during thoracoscopy in the pig had adverse hemodynamic consequences. We prospectively studied 32 patients undergoing thoracoscopy to evaluate the effects of CO2 insufflation in the clinical setting. The end-tidal CO2 pressure, arterial oxygen saturation, mean arterial pressure, heart rate, and central venous pressure were monitored. Measurements were determined at baseline, at the initiation of one-lung ventilation, and at intrapleural pressures of 2 to 14 mm Hg. We found that the insufflation of CO2 of 2 to 14 mm Hg had no significant effect on the end-tidal CO2 pressure, arterial oxygen saturation, heart rate, or mean arterial pressure, but the central venous pressure did rise from 7.00 +/- 1.5 mm Hg to 17.30 +/- 2.53 mm Hg (p < 0.05). We conclude from this that the insufflation of CO2 during thoracoscopy does not have adverse hemodynamic effects in the clinical setting. Therefore, we propose that low-pressure (< 10 mm Hg) insufflation is a safe adjunct to the conduct of routine thoracoscopic surgical procedures.

Anesthetic techniques for thoracoscopy

With the advent of laparoscopic techniques for application in the chest, as well as the development of new video equipment and instrumentation technology, the cardiothoracic surgeon can now perform procedures that, until very recently, were performed only by thoracotomy. Modern thoracoscopy has not reached its final resolution, but a growing number of procedures have been performed that permit some initial recommendations to be made and that define areas of research for the anesthesiologist. A review of the physiology of the lateral decubitus position will act as a basis for developing rational decisions concerning the conduction of anesthesia for thoracoscopy. Future research and experience in thoracoscopy will help to further define appropriate anesthetic techniques.