British Journal of Anaesthesia 114 (1):70-6 (2015)
O.F Kilic, A.Börgers, W.Köhne, M.Musch, D.Kröpfl and H.Groeben
Blog by By Shi Hong Shen, MBBS, BPharm (Hons)
The use of the steep Trendelenburg position and abdominal CO2-insufflation during surgery can lead to significant reduction in pulmonary compliance and upper airway oedema. The postoperative time course of these effects and their influence on postoperative lung function is unknown. Therefore, we assessed intra- and extrathoracic airway resistance and nasal air flow in patients with or without chronic obstructive pulmonary disease (COPD) during robotic-assisted prostatectomy.
In 55 patients without and 20 patients with COPD spirometric measurements and nasal resistance were obtained before operation, 40 and 120 min, and 1 and 5 days after operation. We measured vital capacity (VC), forced expiratory volume in 1 s (FEV1), maximal mid-expiratory and inspiratory flow (MEF50, MIF50), arterial oxygen saturation, and nasal flow. The occurrence of postoperative conjunctival oedema (chemosis) was also assessed.
In patients without COPD, MEF50/MIF50 increased and nasal flow decreased significantly after surgery (P<0.0001) and normalized within 24 h. VC and FEV1 decreased after operation with a nadir at 24 h and recovered to normal until the fifth day (P<0.0001). In patients with COPD, changes in MEF50/MIF50 and nasal flow were similar, while changes in VC and FEV1 lasted beyond the fifth day (P<0.0001).
Robotic-assisted prostatectomy in the steep Trendelenburg position led to an increase in upper airway resistance directly after surgery that normalized within 24 h. The development of chemosis can be indicative of increased upper airway resistance. In patients without COPD, VC and FEV1 were reduced after surgery and recovered within 5 days, while in patients with COPD, the alteration lasted beyond 5 days.
Robotic assisted prostatectomies confer advantages of faster recovery, low pain scores, minimal blood loss and overall good functional results. As a result, it is being increasingly adopted for patients with more significant comorbidities. However, the procedure involves a steep trendelenburg position with insufflation for many hours and could result in increased airway resistance, reduction of pulmonary compliance and fluid shifts from the lower body.
Kilic and colleagues have conducted a prospective cohort study on 80 patients looking at the effects of intra and extrathoracic airway resistance in patients with and without COPD in this setting. They found that upper airway resistance (MEF50/MIF50) increased, and nasal flow decreased but returned to baseline after 24 hours in both groups. Vital capacity and FEV1 decreased with a nadir at 24 hours but recovered on day 5 for the control and persisted beyond day 5 for the COPD group.
The study was limited in that there was uneven number of patients between the 2 arms (60 control, 20 COPD). Unlike the rest of the patients studied, more than half of the patients in the control group did not receive a thoracic epidural for analgesia and had ongoing neuromuscular blockade beyond intubation. This could impact on the ability to perform respiratory function tests for the data collected. Finally, the degree of treatment including use of steroids and bronchodilator therapy was unclear.