Our study is the first to show that nonintubated minimally invasive CWS is safe and feasible in carefully selected patients with multiple rib fractures. Our study showed that the intraoperative and postoperative results were satisfactory. SpO2, PaO2, PaCO2, BP, HR, vital volume and breathing rate were all maintained at normal levels during and after the operation.
No patient required conversion to tracheal intubation in this study. There are several reasons that may account for the above results. First, a previous study showed that patients with a body mass index of more than 30.0 kg/m2 was not suitable for nonintubated 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 reduced to the minimum. Second, most procedures involved in CWS did not involve intrathoracic dissection and thus were not easily affected by vigorous diaphragmatic or mediastinal movement.
Only one patient developed a pulmonary infection after surgery. It is generally accepted that patients with multiple rib fractures who are afraid of coughing are likely to develop pulmonary infections. Since 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 the pulmonary infection may be connected with the trauma itself rather than the anesthesia procedure.
Unlike previous studies [5-9], paravertebral block was performed before anesthesia induction in our study. A previous study showed that preemptive pharmacological blockade was effectively used in surgical patients with satisfactory results . It is generally accepted that preemptive analgesia can alleviate pain and stress reactions, maintain hemodynamic stability, reduce intraoperative bleeding, and lower the incidence rates of cardiovascular and cerebrovascular events . In our study, all patients recovered rapidly with satisfactory postoperative analgesia, which supports 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 to the maximum extent, dividing muscles is still inevitable in CWS. Mechanical ventilation was necessary in all patients during the first half of the operation since muscle relaxants were used, which made satisfactory oxygenation easy to maintain. The loss of an airway during the procedure in a lateral position is a major complication during the operation. If there is air leakage or changes in the laryngeal mask position in the lateral position, the laryngeal mask can be adjusted in a small range or can be replaced into the larynx; tracheal intubation can also be performed if necessary (no such cases were found in this study). Abdominal distention is a major complication after the operation and is usually caused by air leakage around the laryngeal mask. None of the patients developed abdominal distention in this study, which may be attributed to the appropriate choice of laryngeal mask size and the experience of the anesthesiologist. During the second half of the operation, satisfactory oxygenation was also maintained in all patients. An intact parietal pleura in the majority of cases and the short operation time may have contributed to the above results. VARP is a new technique for CWS that allows for an extrathoracic approach using standard plating assisted by laparoscopy, which likely allows for a faster recovery. A previous study reported their experience with performing the VARP technique and concluded that it was feasible in a cadaver model . Our study is the first to report our experience using the VARP technique in patients with multiple rib fractures with satisfactory results, which supports its application in the general patient population to further define patient indications.
Although no study has been performed before, CWS tends to be safer than video-assisted thoracoscopic surgery. First, CWS usually does not involve intrathoracic procedures, which might avoid triggering coughing in spontaneously breathing patients. Our experience in this study showed that no patient developed cough after nonintubated CWS. Second, hypoxemia and hypercapnia are unlikely to occur in patients without open pneumothorax. Since the parietal pleura was intact in most cases of CWS, it was easy to maintain satisfactory oxygenation during surgery. The satisfactory intraoperative results showed that nonintubated CWS in carefully selected patients was safe and feasible.
Although muscle relaxants were used in all patients, the dosage of muscle relaxants in this study was obviously lower than general anesthesia intubation (10 mg vs. 50 mg). A 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 nonintubated CWS could reduce pulmonary complications even without a control group in this study. Since dividing or dissecting muscles is inevitable in CWS, a low dosage of muscle relaxants may make the whole procedure more difficult. The mean operation time was 87.5 minutes, which seemed to suggest that the operation procedure did not become difficult under nonintubated anesthesia. Basedthe operation procedure was difficult in patients with posterior rib fractures due to the appearance of muscle tremors during muscle dissection, which suggests that posterior rib fractures might not be the perfect candidates for nonintubated CWS.
The mean extubation time of the laryngeal mask was 8.9 minutes in this study, which was faster than general anesthesia intubation in our hospital (8.9 minutes vs. more than 20 minutes). Several studies have suggested that early extubation can significantly reduce the risk of adverse events such as laryngotracheal injuries, pulmonary hypertensive crises, pulmonary atelectasis and ventilator-acquired pneumonia [16-17]. A previous study also showed that early extubation could improve patients’ self-care abilities, accelerate the process of blood circulation in the lungs, and promote more rapid recovery in thoracic surgery . The low incidence of complications after surgery in this study may partly be attributed to the early extubation of the laryngeal mask.
The mean postoperative fasting time was 6.1 hours in this study, which was also shorter than general anesthesia intubation in our hospital (6.1 hours vs. more than 8 hours). It is generally accepted that early postoperative feeding can improve the recovery of gastrointestinal peristalsis and nutritional status and can help patients recover more quickly than traditional postoperative feeding . However, some people worry that early postoperative feeding may result in complications such as pneumonia, aspiration, and mortality. The low incidence of complications after surgery suggested that early postoperative feeding after nonintubated chest wall stabilization was safe and feasible.
There were several inevitable limitations in this study. First, the number of included patients was relatively small. Second, a control group receiving CWS under intubated general anesthesia was lacking in order to compare the differences with nonintubated anesthesia. Considering that this technique had not been performed before, this study had to be designed as a single arm with a small sample size to verify the safety and feasibility of this technique. However, the results of this study support the use of further studies that include a control group with a large sample size.
In our study, all patients showed tolerable postoperative pain and postoperative nausea and vomiting, an early postoperative fasting time, and low morbidity. With the satisfactory results of our study, a prospective study comparing nonintubated anesthesia and general intubated anesthesia in CWS would be helpful to further elucidate the safety and value of nonintubated anesthesia.