Our study is the first study showing that non-intubated minimally invasive CWS is safe and feasible in carefully selected patients with multiple rib fractures. Our study showed the intraoperative and postoperative results were satisfactory. SpO2, PaO2, PaCO2, BP, HR, vital volume and breathing rate are all maintained at normal level during and after operation.
No patient required conversion to tracheal intubation in this study. There are several reasons may account for above results. First of all, previous study showed patients with a body mass index of more than 30.0 kg/m2 was not suitable for non-intubated anesthesia due to vigorous diaphragmatic and mediastinal movement . Since the body mass index of patients was strictly limited to lower than 28 kg/m2 in our study, the risk of conversion to general anesthesia was reduce to the minimum. Secondly, most procedures in CWS did not involve in intrathoracic dissection, which were not easily affected by vigorous diaphragmatic and mediastinal movement.
Only one patient developed pulmonary infection after surgery. It is generally accepted that patients with multiple rib fractures who are afraid of coughing is likely to develop pulmonary infection. Since the postoperative analgesia was satisfactory in all patients, it seems unlikely that patients were afraid to cough because of pain in this study. The cause of pulmonary infection may be connected with the trauma itself other than anesthesia procedure.
Unlike previous studies [5–9], paravertebral block was performed before anesthesia induction in our study. Previous study showed preemptive pharmacological blockade had been effectively used in surgical patients with satisfactory results . It is generally accepted that preemptive analgesia can alleviate pain and stress reaction, maintain hemodynamic stability, reduce intraoperative bleeding, lower the incidence rates of cardiovascular and cerebrovascular events . In our study, all patients recovered rapidly with satisfactory postoperative analgesia, which supported the further application of preemptive analgesia in CWS.
Compared with video-assisted thoracoscopic surgery, division of thoracic muscles in CWS is more extensive. Although muscle-sparing incisions and minimized approaches can preserve muscles in the maximum extent, dividing muscles is still inevitable in CWS. Mechanical ventilation was necessary in all patients during the first half part of operation since muscles relaxants were used, which made satisfactory oxygenation easy to maintain. Abdominal distention is a major complication after operation, which was usually caused by the air leakage around laryngeal mask. None patients developed abdominal distention in this study, which may attribute to appropriate choice of laryngeal mask size and anesthesiologist with well-experienced anesthesia skill. During the second half part of operation, satisfactory oxygenation was also maintained in all patients. Intact parietal pleura in major cases and short operation time may contribute to above results.
VARP is a new technique for CWS allows for an extrathoracic approach using standard plating assisted by laparoscopy, which is likely allow for faster recovery. Previous study reported their experience of performing VARP technique and concluded that it was feasible in the cadaver model . Our study firstly reported our experience of using VARP technique in patients with multiple rib fractures with satisfactory results, which supports application in the general patient population to further define the patient indications.
Although no study has been performed before, non-intubated CWS is tended to be safer than video-assisted thoracoscopic surgery. Firstly, CWS usually does not involve intrathoracic procedures, which might avoid triggering coughing in spontaneously breathing patients. Our experience in this study showed no patient developed cough in non-intubated CWS. Secondly, hypoxemia and hypercapnia is not likely to be happened in patients without open pneumothorax. Since the parietal pleura were intact in most cases of CWS, it is easily to maintain satisfactory oxygenation during surgery. The satisfactory intraoperative results showed non-intubated CWS in carefully selected patients was safe and feasible.
Although muscles relaxants were used in all patients, the dosage of muscles relaxants in this study was obviously lower than general anesthesia intubation (10 mg vs. 50 mg). Previous study showed that residual neuromuscular blockade after anesthesia is a cause of increased pulmonary complications such as oxygen desaturation, postoperative pneumonia, airway obstruction, and reintubation . Therefore, it is reasonable to speculate that non-intubated CWS can reduce pulmonary complications even without a control group in this study. Since dividing or dissecting muscles is inevitable in CWS, low dosage of muscles relaxants may make the whole procedure more difficult. The mean operation time was 87.5 minutes, which seemed to suggest that operation procedure was not getting difficult under non-intubated anesthesia. Basing on our experience, we did find that operation procedure was getting difficult in patients with posterior rib fractures due to the muscle tremor during muscles dissecting, which suggested posterior rib fractures might not be the perfect candidate of non-intubated CWS.
There were inevitable certain several limitations in this study. Firstly, the number of included patients was relatively small. Secondly, a control group who received CWS under intubated general anesthesia was lacked to compare the differences with non-intubated anesthesia. Considering this technique had not been performed before, this study had to be designed as a single arm with small sample to verify the safety and feasibility of this technique. However, the results of this study do support further study including a control group with large sample size.
In our study, all patients showed tolerable postoperative pain, postoperative nausea and vomiting, early postoperative fasting time, low morbidity. With satisfactory results in our study, a prospective study comparing non-intubated anesthesia and general intubated anesthesia in CWS would be helpful to further elucidate the safety and value of non-intubated anesthesia.