Fiberoptic bronchoscopy is an essential common diagnostic method for lung diseases [1] . The procedure is an invasive procedure and enough sedation is required [2] . Patients who are candidate for bronchoscopy are involved with respiratory problems. Airway manipulation in such patients may result in exacerbation of respiratory problems [3] . However, maintaining the tone of airway muscles and patient cooperation are necessary for successful and safe procedure [4] .

To prevent respiratory complication we have to induce light sedation or partial unconsciousness [5] which is accompanied by unsuccessful procedure and non-satisfied patient and operator.

Concomitant use of opioids and benzodiazepines will result in respiratory problem [6] . Intravenous ketamine is an analgesic drug without severe respiratory problems but is not a common modality due to severe hallucination [7] . Subcutaneous Dissociative Conscious Sedation (DCS) is a safe method for painful procedures [8] [9] . It will result in patient’s cooperation accompanied by analgesia and enough sedation. Induction of conscious sedation by ketamine via subcutaneous rout was described for the first time by Javid et al in 2009 in “Airway management and Anesthesia in head and neck surgery” congress and then it was introduced as an alternative to airway blocks [8] [10] . Efficacy and safety of this method have been previously established and will result in patients’ cooperation. Then this study was designed in order to compare subcutaneous Dissociative Conscious Sedation (sDCS) with Conscious Sedation in fiberoptic bronchoscopy.

In this double-blind randomized clinical trial, 110 patients (age 18 - 65 years and ASA classes of I-III), scheduled for fiberoptic bronchoscopy were enrolled and randomly assigned to receive either SC ketamine plus IV fentanyl (Dissociative Conscious Sedation) or placebo plus IV fentanyl (conscious sedation) and the efficacy and side effects were assessed and compared. The fentanyl dose was 2 ug/kg and up to 3 ug/kg if needed. The dose of subcutaneous Ketamine was 0.5 mg/kg. The nasopharyngeal anesthesia was induced by 2 ml of intranasal lidocaine and 4% lidocaine spray. In non-cooperative subjects, extra doses of fentanyl were administered incrementally up to 3 ug/kg. If the patient was not cooperative enough yet to continue the procedure after administration of extra doses of fentanyl up to 3 ug/kg, the patient was excluded.

Narcotic abuse, uncontrolled hypertension, psychological diseases and untreated ischemic heart disease and increased ICP were the exclusion criteria. The informed consent form was signed by all the patients. All bronchoscopies were performed by the same operator. All SC injections were performed on the anterior aspect of forearm. The procedure was initiated 10 minutes after induction of sedation. The opioid injection was performed titrated.

In cases of nausea and vomiting metoclopramide (10 mg) was administered.

The randomization was by block method and was concealed by anesthesiology resident. The patient and other personnel and also the operator were not informed about the used method for each patient. The consciousness level, heart rate, systolic and diastolic blood pressures, arterial blood oxygen, and electrocardiography were checked. Also the recovery time was recorded in both groups.

Patient’s and endoscopist’s satisfaction were also evaluated at the end of the procedure. Cough reflex and swallow reflex were evaluated. Apnea, desaturation, nausea and vomiting were recorded.

Data analysis was performed among 110 subjects including 55 patients in intervention group and 55 subjects in control group. Data analysis was performed by SPSS (version 13.0) software [Statistical Procedures for Social Sciences; Chicago, Illinois, USA]. Chi-Square, Fisher, Independent-Sample T, and Repeated-Measure ANOVA test were used and were considered statistically significant at P values less than 0.05.

The mean age was 40.6 and 39.2 years in ketamine and placebo groups, respectively (P > 0.05). 74.5% and 60% were male in ketamine and placebo groups, respectively (P > 0.05). As shown in Figures 1-4 the heart rate, oxygen saturation, and systolic and diastolic blood pressures were significantly differed between groups (P < 0.05). All side effects except apnea and swallowing reflex were significantly differed across the groups (Table 1). Patients satisfaction rate was 78.2% in ketamine group and 12.7% in placebo group (P = 0.0001) and the operator satisfaction rate was 90.2% and 18.2% in ketamine and placebo groups respectively (P = 0.0001).

No hallucination was observed in groups. The incidence of recall was significantly lower in ketamine group.

Fentanyl dose was significantly lower in ketamine group (Table 2).

*Cough was severe in 2.3% of Ketamine group and 59.6% in control group.

This study demonstrated that systolic and diastolic blood pressures and heart rate were significantly different between groups and cardiovascular stability was significantly higher in ketamine group. Analgesic consumption was significantly lower in dissociative group (P < 0.05).

Javid et al [8] introduced Dissociative Conscious Sedation instead of general anesthesia for laparoscopic peritoneal catheter insertion. The procedure was optimal in all patients and also the systolic blood pressure was lower in SC ketamine compared with IV ketamine group. The authors were concluded that method was considered as an alternative method for general anesthesia. High cardiovascular stability was observed in sDCS group [9] and this was in congruence with our study. DCS is a safe and optimal method for conscious patients and has been used as an alternative to airway regional blocks [10] .

New strategies for difficult airway in surgery and anesthesia would result in more patients’ safety and less mortality and morbidity [11] . Ketamine would result in endothelin release and consequently less airway constriction [12] . The SC ketamine would have lower cardiovascular side effects by reduction of intraoperative blood pressure compared with other treatments [8] - [11] . IM injection also showed more cardiac protection compared with IV modality [13] [14] . This method was recommended to use because of less cardiac events [9] [14] . Intravenous ketamine is a good modality but may result in fewer acceptances by both patient and physician [7] . Using SC ketamine in ICU patients demonstrated that fentanyl was accompanied by morestable hemodynamic [9] . This method is safe and optimal and could be recommended as a non-invasive method [10] . Javid et al found the sDCS method suitable in patients with predicted difficult airway [10] .

Totally, according to the obtained results, it may be concluded that use of subcutaneous ketamine plus narcotic (subcutaneous dissociative conscious sedation) in comparison to placebo plus narcotic (conscious sedation) will result in significantly more efficacy and low side effects in fiberoptic bronchoscopy and its use is recommended.

The study was supported by Tehran University of Medical sciences Research center.

Mihan J.Javid,ZohaAlinejad,AsgharHajipour,ZahraKhazaeipour, (2015) Subcutaneous Dissociative Conscious Sedation (sDCS) an Alternative Method of Anesthesia for Fiberoptic Bronchoscopy. Open Journal of Anesthesiology,05,149-154. doi: 10.4236/ojanes.2015.57027