Search PubMed⌕ Search

Biomedical subjects

T C Kao

Publications and source records attributed to T C Kao.

43 records · Page 3Linked to original sources
PubMedDate not supplied

Time course of the effects of cervical epidural anesthesia on pulmonary function.

BACKGROUND AND OBJECTIVES: During cervical epidural anesthesia the C4, C5, and sometimes C3 nerve roots are anesthetized. One might therefore expect pulmonary compromise due to the block of the phrenic nerve if anesthesia extends to C3. This study was conducted to measure the effects of cervical epidural anesthesia using 2% lidocaine on pulmonary function, with specific attention given to the time course of pulmonary changes in relation to spread of analgesia. METHODS: Fifteen adult patients without preexisting lung disease undergoing carotid endarterectomy, breast surgery, or cervical epidural steroid injection were enrolled. Cervical epidural anesthesia was performed at the C7-T1 interspace using 300 mg lidocaine with epinephrine. Pulmonary function, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), maximum inspiratory pressure (MIP), and SpO2 while breathing room air were measured prior to and 5, 10, 20, and 40 minutes after lidocaine injection. RESULTS: Analgesia to pinprick reached median dermatomes of C3 to T8 (range: C2-T12) by 20 minutes after lidocaine injection. FEV1 and FVC decreased approximately 12-16% between 20 and 40 minutes after injection. Maximum inspiratory pressure and SpO2 did not significantly change. CONCLUSIONS: Cervical epidural anesthesia using 300 mg lidocaine results in measurable reduction in bedside pulmonary functions concomitant with the spread of analgesia to the C3 dermatome. These changes were complete 20 minutes after lidocaine injection. In patients without preexisting lung disease, these changes were not clinically significant, except in one patient. We conclude that motor block of the phrenic nerve is incomplete under the conditions of this study.

Adult↗
PubMedDate not supplied

The recovery profile of hyperbaric spinal anesthesia with lidocaine, tetracaine, and bupivacaine.

BACKGROUND AND OBJECTIVES: Surgical procedures previously considered too lengthy for the ambulatory surgery setting are now being performed during spinal anesthesia. The complete recovery profile of tetracaine and bupivacaine are now of interest but are not available in the literature. This study was conducted to compare times to ambulation, voiding, and complete block resolution, as well as the incidence of back and radicular pain, after spinal anesthesia with lidocaine, bupivacaine, and tetracaine. METHODS: Twelve adult volunteers underwent spinal anesthesia on three separate occasions with three local anesthetics (lidocaine 100 mg, bupivacaine 15 mg, and tetracaine 15 mg in hyperbaric solutions) in random order and in a double-blind fashion. A 24-gauge Sprotte spinal needle was placed at the L2-3 interspace. The level of analgesia to pinprick was determined moving cephalad in the midclavicular line until a dermatome was reached at which the prick felt as sharp as over an unblocked dermatome. One dermatome caudad to this point was recorded every 5 minutes as the level of analgesia. We also recorded the times to voiding, unassisted ambulation, and complete resolution of sacral anesthesia. RESULTS: There was no difference between tetracaine and bupivacaine in time taken for two- and four-segment regression of the analgesia level. However, times to ambulation and complete resolution of the block were significantly shorter with bupivacaine then with tetracaine. With lidocaine, times to four-segment regression, ambulation, voiding, and complete regression of the block were significantly shorter than with bupivacaine and tetracaine. Time to two-segment regression did not differ among local anesthetics. Back and radicular pain symptoms were reported by three subjects after lidocaine subarachnoid block but not after tetracaine or bupivacaine. CONCLUSION: Among individual subjects, lidocaine exhibited the shortest recovery profile. However, the recovery profiles of the three anesthetics were very variable between subjects. Time to meeting discharge criteria after bupivacaine or tetracaine was faster in a few subjects than that after lidocaine in other subjects. For ambulatory anesthesia, times to two- and four-segment regression do not accurately predict time to readiness for discharge after spinal anesthesia.

Adult↗
PubMedDate not supplied

The relative incidence of anterior cruciate ligament injury in men and women at the United States Naval Academy.

The purpose of this study was to evaluate the relative risk of anterior cruciate ligament injury in female versus male midshipmen at the United States Naval Academy. From 1991 to 1997, we recorded the incidence of anterior cruciate ligament injury during intercollegiate athletics, intramural athletics, and military training. The subjects were male and female varsity athletes, coed intramural athletes, and participants in military training consisting of the obstacle course and instructional wrestling. All patient data were collected at the time of injury. Records filed at the intramural sports office, along with a questionnaire completed by coaches and trainers, were used to estimate midshipmen exposures. Results showed that in intercollegiate soccer, basketball, and rugby, women had a relative injury risk of 3.96 compared with men. In coed soccer, basketball, softball, and volleyball, the women's relative injury risk was 1.40 compared with men. In military training, women had a relative injury risk of 9.74 compared with men. In comparing overall annual anterior cruciate ligament injury rates among midshipmen, we found that women had a relative injury risk of 2.44 compared with men. We concluded that female midshipmen have an increased relative risk of anterior cruciate ligament injury as compared with men in intercollegiate athletics, basic military training, and throughout their service academy career. This increase was not statistically significant at the intramural level of athletics.

Adolescent↗
PubMedDate not supplied

Differential epidural block.

BACKGROUND AND OBJECTIVES: Loss of sensation to pinprick and cold are commonly used to test the extent of epidural anesthesia. To see what difference exists between the level of epidural block determined by various sensory modalities, we performed this study in ten volunteers using epidural anesthesia with plain 3% chloroprocaine hydrochloride. METHODS: Four injections of chloroprocaine were made via an epidural catheter inserted at L2-3 with increasing larger volumes. Sensory modalities tested were (1) absence of sensation when tested by pinprick (anesthesia), (2) loss of a sharp sensation compared to an unblocked dermatome when tested by pinprick (analgesia), and (3) loss of cold sensation when tested with an alcohol swab compared to an unblocked dermatome. RESULTS: At 20 minutes after each injection the level of anesthesia was found to be most caudad and the level of analgesia most cephalad. The zone of differential block was greater than four dermatomes at the highest level of block tested. The level of loss of cold sensation was found between the other two levels. Differences between the levels of analgesia and cold sensation tended to be greater with more extensive block. Differences between levels of anesthesia and cold sensation did not significantly change as the extent of epidural anesthesia was increased. CONCLUSIONS: This study establishes the existence of a differential epidural anesthesia during high thoracic block with chloroprocaine and suggests that the intensity of block diminishes as distance from site of injection increases.

Adult↗
PubMedDate not supplied

Differential epidural block. Does the choice of local anesthetic matter?

BACKGROUND AND OBJECTIVES: It is well established that spinal anesthesia results in a differential block to the sensations of pinprick and cold temperature discrimination. However, the existence of differential block during epidural anesthesia has not always been accepted. Recently, it has been shown that lumbar epidural anesthesia with chloroprocaine and lidocaine produces a differential block to pinprick and cold sensation. The purpose of this study was to determine if the choice of local anesthetic used for epidural anesthesia has any influence on the relative levels of anesthesia, analgesia, and cold sensation. METHODS: The authors studied nine healthy subjects; each was studied three times and received one of three local anesthetics (0.75% bupivacaine, 2% lidocaine, and 3% chloroprocaine) via an epidural catheter placed into the second or third lumbar epidural space. The authors tested the following modalities compared to an unblocked dermatome: anesthesia, loss of sensation to pinprick; analgesia, loss of an equally sharp sensation to pinprick; and cold sensation, loss of cold sensation to alcohol. RESULTS: Twenty minutes after injection of the local anesthetic, zones of differential sensory block existed for all three agents tested. Anesthesia and analgesia were the most caudad and cephalad, respectively, while loss-to-cold sensation was found to be between these two levels. There was no significant difference in the dermatomal level achieved among the three local anesthetics tested. Sensory testing data observed 10 minutes later showed that no significant change had occurred. CONCLUSIONS: This study reaffirms the existence of differential sensory block during epidural anesthesia and establishes that the observed differential block appears to be independent of the local anesthetic used.

Adult↗
PubMedDate not supplied

Inhalation of nitrous oxide expands epidural air bubbles.

BACKGROUND AND OBJECTIVES: Epidural air bubbles are known to persist for more than 24 hours after injection. Nitrous oxide may cause expansion of these bubbles. METHODS: Nine dogs were anesthetized. Ten mL air and 9 mL of iophendylate were injected into the lumbar epidural space. Control animals (n = 3) breathed halothane in 100% oxygen. Experimental animals (n = 6) breathed halothane in 70/30 nitrous oxide/oxygen. Lateral radiographs were taken before and just after injection, and again 3 hours after breathing either 70% nitrous oxide or 100% oxygen. Epidural space pressure was monitored and recorded during these 3 hours. RESULTS: In all experimental animals, an increase in bubble size was observed. In the control animals, bubble size either remained the same or decreased. Epidural space pressure did not change in any animal. CONCLUSIONS: Inhalation of nitrous oxide results in expansion of epidural air bubbles. This may cause displacement of epidural local anesthetics it large volumes of air are present in the epidural space.

Anesthesia, Epidural↗