Introduction: It has been demonstrated that intranasal opioid titration has a rapid onset of action and can provide satisfactory management of postoperative pain [10, 12, 14]. In these studies the intranasal titration was carried out by the investigator. Self-administration of an opioid intranasally by patients requires a spray bottle with safety precautions of an equivalent standard to those offered by an intravenous PCA device. We describe a device for patient-controlled intranasal analgesia (PCINA) that meets these safety requirements.
Methods: The Baxter PCA on demand system consists of a mechanically driven infusor, a flow restrictor, and a patient control module for bolus administration. The flow restrictor provides a flow rate of 5 ml/h or 2 ml/h. This Baxter intravenous PCA system has been subjected to a slight modification to adapt it for PCINA. The patient control module has a bolus volume of 0.5 ml and in this modification it is attached, instead of to an intravenous line, to a narrow, 26-gauge plastic cannula with the needle tip removed (Fig. 1). To check the accuracy of the volume delivered, three PCINA devices with a flow rate of 5 ml/h (filling time of 6 min for the 0.5-ml bolus volume) and three PCINA devices with a flow rate of 2 ml/h (filling time of 15 min for the 0.5-ml bolus volume) were examined at defined time intervals. The PCINA devices were filled with distilled water and the volume demanded was immediately determined by means of a high-precision scale. Three determinations of the volumes delivered were performed. In an initial unblinded pilot observation in five orthopaedic patients, PCINA (for a 4-h period) was compared with the conventionally prescribed pain medication (for a subsequent 5-h period). For intranasal opioid administration, fentanyl (1 ml=0.05 mg) was used. At every evaluation point, pain intensity was evaluated with the aid of a 101-point numerical rating scale (0 = no pain, 100 = worst pain possible). At the end of both examination periods (PCINA/conventionally prescribed pain medication), overall patient satisfaction with the method of pain management experienced was evaluated (graded: very good, good, satisfactory, bad, very bad, not acceptable).
Results: The volumes delivered from the three PCINA devices with a flow rate of 5 ml/h (PCINA device 6') and from the three PCINA devices with a flow rate of 2 ml/h (PCINA device 15') are presented in Fig. 4. The subjective pain intensities measured with the 101-point numerical rating scale are demonstrated in Fig. 5. The patients used 0.28+/-0.097 mg fentanyl (0.15-0.45 mg) during the 4-h period of PCINA. No patients had any difficulty using the PCINA device. No technical problems arose with any of the devices. No patient complained of intranasal pain or burning during or after nasal administration. At the end of the study overall patient satisfaction with PCINA was judged as very good (2 patients), good 2 patients) or satisfactory (1 patient). The relief obtained with the customarily prescribed pain medication was judged as satisfactory (1 patient) or bad (4 patients).
Conclusion: We conclude that the PCINA device presented fulfils the PCA device safety requirements. The bolus volume delivered by the device is precise and follows the manufacturer's specifications for flow rate and bolus volume. Initial.