Effect of cervical epidural blockade with 2% lidocaine plus epinephrine on respiratory function.
BACKGROUND
Cervical epidural anesthesia has been used widely for surgery of upper limbs. Although cervical epidural anesthesia with local anesthetic of 2% lidocaine (plain) has demonstrated the safety in respiratory function in spite of unavoidable phrenic and intercostal palsies to certain extent, the replacement of local anesthetics with 2% lidocaine plus epinephrine has not been investigated yet. I conducted this study to look into the effect of 2% lidocaine plus epinephrine on respiratory function.


METHODS
I collected data from 50 patients with mean age of 24 +/- 3 yrs, mean weight of 65 +/- 10 kg, ASA status: I-II without preoperative pulmonary dysfunction undergoing orthropedic open-reduction with internal fixation because of fractures of upper limbs. Cervical epidural space (C7-T1) was approached by hanging-drop method, using a 17G Tuohy needle. A catheter was inserted craniad to a distance of 12 cm. Pulmonary function measurement and arterial blood gas data were obstained before, 20 min, 50 min and 105 min after injection of 12 mL 2% lidocaine with 1:200,000 epinephrine.


RESULTS
The anesthesia levels were between C3-T3 and obtained 15 +/- 2 min after injection. Mean arterial blood gas analysis showed mild respiratory acidosis at 20 min (PaCO2: 48 +/- 3 mmHg) and 50 min (PaCO2: 44 +/- 2 mmHg). The measured values of inspiratory vital capacity (IVC), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), peak expiratory flow (PEF) when compaired with control values, were decreased about 18.0% and 12.1% of the control values at 20 min and 50 min respectively. The ratios of FEV1/VC, FEV1/FVC were still within normal limits (> 80%). The results were significantly compatible with the criteria of mild restrictive type of pulmonary function.


CONCLUSIONS
Cervical epidural anesthesia with 2% lidocaine plus epinephrine could reduce lung volumes and capacities, resulting from partially paralytic intercostal muscles and diaphragm innervated respectively by thoracic intercostal nerve and phrenic nerve. Without inadvertant total spinal or intravenous anesthesia or pre-existing pulmonary dysfunction, the patients with normal lungs could tolerate these changes well with the procedure.
Huang
Chih-Hung
CH
Department of Anesthesiology, Taichung Armed Forces General Hospital, Taichung County, ROC. wei-chen@803.org.tw
D000328:Adult; D000767:Anesthesia, Epidural; D004837:Epinephrine / Q000008:administration & dosage*; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage*; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests
D008012:Lidocaine; D004837:Epinephrine