At present, sufentanil, fentanyl and other opioid analgesics injected intravenously during the induction period of clinical anesthesia showed strong analgesic effect and little influence on hemodynamic indexes [14, 15], and can effectively inhibit tracheal intubation response (such as increased heart rate, increased blood pressure, etc.)[16, 17]. However, it is easy to cause choking and coughing reaction in different degrees within 1 min of intravenous injection[18]. For patients with hypertension, pulmonary bullae, hemangioma and intracranial hypertension, it may cause severe consequences.
The various incidence among different studies might be due to the different doses of sufentanil used and the differences in concentrations, administration rate, race and age[19]. In an study by Agarwal et al. [20] sufentanil 0.3 µg/kg injected over 5 s elicited cough in 15.8% of patients, while in another study by Li et al. [21] the incidence of cough was 37% after the injection of sufentanil 0.5 µg/kg within 3 s, with a high dose of sufentanil (1 µg/kg), the incidence of sufentanil-induced cough could be up to 45.8%. We have previously considered that large doses of sufentanil can lead to prolonged recovery time, while small doses of sufentanil can not meet the needs of surgery analgesia. In our study, we administered sufentanil 0.5 µg/kg intravenously within 3 seconds before operation in the C group of normal saline. Within 1 minute, the incidence of sufentanil induced cough was 31.1%.This is similar to the conclusion of relevant research.
A lot of studies have been done on the mechanism of sufentanil induced cough response, but the relevant mechanism is still not very clear[3–5]. It may be related to sufentanil activating the C-fiber receptor of the bronchus, adapting the pulmonary stretch receptor (RARs), inducing the airway hyperresponsiveness, inhibiting the efferent impulse of the sympathetic nerve, making the vagus nerve in a comparative advantage, and finally leading to the occurrence of the choking cough response[5, 6].
To provide patients with safe and comfortable medical experience is also the responsibility of anesthesiologists. Flurbiprofen axetil is a nonsteroidal drug commonly used in clinic. Geng W J, et al.[22] reported that using 100 mg flurbiprofen axetil before operation can significantly reduce the incision pain, reduce the excitement and systemic inflammation of patients after operation. Fukumori N, et al [23] investigated 71 patients with total hip replacement in Japan and found that intravenous acetaminophen can significantly reduce the pain of patients within 24 hours after early operation. The pretreatment of ketorolac tromethamine injection also played a role in the recovery period of anesthesia, significantly reducing the postoperative incision pain of patients, and the incidence of restlessness caused by pain and other adverse stimulation naturally decreased significantly. To a certain extent, it provided patients with comfortable medical experience and humanistic care.
Ketorolac tromethamine is a new nonsteroidal anti-inflammatory drug (NSAID). Motov S, et al. [24] found that intravenous infusion of ketorolac tromethamine of 30 mg can significantly improve the moderate to severe pain of emergency patients. Studies by Yang H L et al.[25]suggested that the use of injection of ketorolac tromethamine before tracheal intubation can reduce the percentage of sore throat caused by endotracheal intubation from 71.6–21.1%. Compared with other NSAID, ketorolac tromethamine has less anti-inflammatory effect and stronger analgesic effect, which has been widely used in clinic [10, 26]. At present, there are few reports about ketorolac tromethamine reducing sufentanil-induced cough response. It has been reported that intravenous injection of dezocine before anesthesia induction can inhibit the cough response induced by sufentanil or fentanyl to some extent by activating K receptor and inhibiting histamine release[5].Considering that ketorolac tromethamine is a nonsteroidal anti-inflammatory drug, the mechanism of ketorolac tromethamine injection reducing cough response may be related to the reduction of histamine release and other reasons [10, 26].
In order to evaluate the possible adverse reactions and safety of ketorolac tromethamine injection pretreatment, we compared the mean arterial pressure, heart rate and blood oxygen saturation values of the two groups of patients at different time points. The results of this study suggest that pretreatment of ketorolac tromethamine injection would not have adverse effects on vital signs of patients.
5 minutes before anesthesia induction, intravenous ketorolac tromethamine 0.5 mg/kg pretreatment can significantly reduce the incidence of choking and coughing reaction in induction period of general anesthesia patients, and can significantly reduce restlessness in recovery period of patients, which is safe and economic.
There are also some deficiencies in our research. First, due to the limitation of objective conditions, we have not studied the mechanism of ketorolac tromethamine inhibiting cough response and can not give more reasonable inferences about the relevant mechanisms. We just describe the relevant effects objectively, because there is no relevant report about ketorolac tromethamine injection or other nonsteroidal drugs inhibiting sufentanil-induced cough. Second, the pretreatment dose of ketorolac tromethamine (0.5 mg/kg) is not necessarily the most appropriate dose for ketorolac tromethamine to inhibit sufentanil induced cough response, but given according to the early postoperative analgesic dose of the drug instructions [10].Third, our study is a single center study with a small sample size. In order to determine whether pretreatment of ketorolac tromethamine injection can reduce sufentanil induced cough response, we still need a large sample and multicenter study.