The study was approved by PGIMER ethics committee of Postgraduate Institute of Medical Education and Research, Chandigarh, India. Written informed consent was obtained from all subjects participating in the trial. The trial was prospectively registered prior to patient enrollment at clinicaltrials.gov (NCT03081728, Principal investigator- Dr. Pankaj Kushal, Date of registration- 16/03/2017). The study was conducted in the trauma centre of our tertiary care referral hospital from April to November 2017. Patients aged 18–65 years and belonging to American Society of Anesthesiologists (ASA) physical status I-III with either fractures of the proximal humerus or shoulder dislocations were assessed for eligibility. Patients with polytrauma, head injury (GCS<15) and chronic opioid abuse were excluded from enrolment in the study.
Detailed pre-anesthetic workup was carried out in all eligible patients after their consent for participation in the study. Patients were non-randomly allocated into two groups based on the post-operative analgesic modality employed:
Group I: Patient controlled interscalene analgesia (PCIA)
Group II: Multimodal analgesia (MA).
Patients with coagulopathy, severe respiratory disease (FEV1/FVC <0.7 and FEV1 < 80% of predicted), infection at the block site, prior history of neck surgery or radiation to the neck, associated neurological deficit in the arm or with suspicion of nerve injury, allergy to amide local anaesthetics and inability to operate PCA were included in MA group.
Measurement of baseline diaphragmatic excursion (Group I): M-mode sonography was done in the pre-operative holding area. A low frequency curvilinear transducer (2–5 MHz, SonoSite HFL with Micro Maxx or M-Turbo, Bothell, WA, USA) placed in anterior subcostal space was used to visualize the liver/spleen and the hemi diaphragm (identified as a hyperechoic line). Diaphragmatic excursions of three respiratory cycles were imaged, values were averaged and recorded (Figure 1A).
General Anesthesia: In theoperating room monitors were attached (electrocardiography (ECG), pulse oximetry and non-invasive blood pressure) and intravenous line secured. Sleep dose of propofol (2–2.5 mg/kg) and morphine (0.1mg/kg) was administered. Ventilation by bag and mask was followed by administration of muscle relaxant (0.1 mg/kg of Vecuronium) to facilitate tracheal intubation. Maintenance of anesthesia was done with O2/N2O/Isoflurane (1 Minimum alveolar concentration). Post-operative pain was managed as per group allocation:
PCIA (Group I): Interscalene perineural catheter placement was done before extubation using aseptic technique. A 38 mm broadband linear array high frequency transducer (HFL 38/13–6 MHz, SonoSite Inc, Bothell, WA, USA) was placed at the level of the cricoid cartilage. C5, C6 and C7 nerve roots were visualized and an 18G epidural needle was inserted using in plane technique till the needle tip was positioned between the C6 and C7 nerve root next to the hyperechoic layer of the plexus (periplexus technique). Intravascular needle placement was ruled out by aspiration and 3–4 ml of saline was injected to hydro dissect the potential space. A non-stimulating multi-orifice catheter was advanced past the needle tip and tunneled subcutaneously in a posterior and medial trajectory below the hairline. 10 ml of 0.5% ropivacaine was administered through the catheter and spread of local anaesthetic confirmed using US.
MA (Group II)Acetaminophen (1 gm) and diclofenac 75 gm was administered before extubation in patients and subsequently continued in the post-operated period on a thrice and twice a day dosing respectively.
All patients received antiemetic prophylaxis. Neuromuscular blockade was reversed with neostigmine (50µg/kg) and glycopyrrolate (5–10 µg/kg) after return of motor power. Patients were extubated and shifted to the PACU.
Post-operative monitoring of diaphragmatic mobility and pain management: Following parameters were recorded at Time0(After stabilization in the PACU), TimePOSTOPERATIVE(4,6,12,24 hours)
- Diaphragmatic movement: Using real-time M mode ultrasonography as described above in patients in Group I and classified as:
- Complete paralysis(Figure 1B) - if either of the below mentioned finding was seen
- Reduction of more than 75% of diaphragmatic movement
- No movement
- Paradoxical movement.
- Partial paralysis- 25%–75% reduction of diaphragmatic movement
- No paresis- Less than 25% reduction of diaphragmatic movement
- Patient satisfaction visual analog score {ranging from 0 (not satisfied) to 5 (entirely satisfied)}
- Pain: Numerical rating scale ranging from 0 (no pain) to 10 (most severe pain imaginable).No intervention was done for patients with (NRS)<3. Management of pain in patients with (NRS)>3 is summarised in Figure 2.
- Post-operative complications: Nausea, vomiting, pruritus, shivering, delirium, abnormalities in vital parameters (HR, BP, SPO2) etc were recorded and managed. Patients in Group I were questioned for any clinical feature suggestive of a blockade of the phrenic nerve (breathlessness), sympathetic nerves (ptosis, miosis, anhidrosis), recurrent laryngeal nerve (hoarseness) or an accidental epidural or subarachnoid injection. Catheter dislodgements, local inflammation, pericatheter leak of local anaesthetic were recorded.
PCIA was initiated (INFUTEK 405, Simtek Medico Systems, Patel Rd, Goregaon, Mumbai, India) in patients in Group I with NRS<3 at TimePOSTOPERATIVE(4 hours) to deliver background infusion of 2 ml/hr, bolus of 5ml (0.2% of ropivacaine) with lockout interval of 30 minutes for a total duration of 24 hours. Patients with NRS>3 were managed as described in Figure 2.
STATISTICAL ANALYSIS
Data was analyzed using the Statistical Package for Social Science (SPSS) version 22.0. Descriptive statistics (means, standard deviation (SD), frequencies, and percentages) were used to characterize the sample. Continuous data e.g. age, weight, duration of anesthesia, heart rate (HR), mean arterial pressure (MAP), etc was expressed as mean±SD. Categorical data e.g. gender, incidence of paralysis are expressed as frequency and percentage. P value of <0.05 was considered as statistically significant and <0.001 was considered as highly significant.
Sample size calculation: Incidence of hemidiaphragmatic paralysis with continuous interscalene brachial plexus block (CISB) has been reported to be 41%. We presumed that with the low dose regime used in our study the incidence would be 30%. In order to detect this difference with an a error of 0.05 and power of 80%. Allowing for a 10% drop-out rate, we planned to recruit a total of 54 subjects.Thus a sample size of 27 for each group was selected.