Catherine L. Hamilton

Changes in the position of epidural catheters associated with patient movement

Background: Epidural catheter movement has been noted with change of patient position and can result in inadequate anesthesia. This study was designed to measure movement and to develop a technique that minimizes catheter displacement. Methods: In 255 parturients requesting epidural anesthesia for labor or cesarean section, a multiorificed lumbar epidural catheter was inserted with the patient in the sitting flexed position. The distance to the epidural space, length of catheter inserted, and amount of catheter position change as the patient moved from the sitting flexed to sitting upright and then to the lateral decubitus position were measured before the catheter was secured to the skin. Adequacy of analgesia, the need for catheter manipulation, and whether the patient was considered obese were noted. Data were grouped according to body mass index (BMI): 30 kg/m 2 . Results: The groups did not differ with respect to the length of catheter initially inserted or changes in catheter position between initial taping and removal. The distance to the epidural space differed significantly among the groups, increasing with greater BMI. Catheters frequently appeared to be drawn inward with position change from the sitting flexed to lateral decubitus position, with the greatest change seen in patients with BMI > 30. Only nine catheters were associated with inadequate analgesia, four of which were replaced. No analgesic failures occurred in the BMI > 30 group. In patients judged by the anesthesiologist to be obese or to have an obese back, BMI was greater, and the distance to the epidural space and the magnitude of catheter movement with position change were greater than in those who were not obese. Conclusions: Epidural catheters moved a clinically significant amount with reference to the skin in all BMI groups as patients changed position. If catheters had been secured to the skin before position change, many would have been pulled partially out of the epidural space. To minimize the risk of catheter displacement, particularly in obese patients, we recommend that multiorificed catheters be inserted at least 4 cm into the epidural space and that patients assume the sitting upright or lateral position before securing the catheter to the skin.

High sensory block after intrathecal sufentanil for labor analgesia.

INTRATHECAL opioids for labor analgesia have become popular in recent years because they provide rapid, profound analgesia without motor blockade. Several s tudies 1-3 have found intrathecal opioids safe for both mother and fetus, citing few complications. We report a series of six cases exhibiting a high sensory block after intrathecal sufentanil for labor analgesia. With the exception of one patient (case 3), all were healthy parturients in active labor with a term, singleton, vertex fetus. In each case, intrathecal sufentanil was administered as part of a combined spinal-epidural technique. With the patient in the sitting position, the lumbar epidural space was identified using a loss-of-resistance technique with an 18-G Tuohy needle. Intrathecal injection was performed via a 1 20-mm (Sprotte) or 127-mm (Gertie Marx) 24-G pencil-point spinal needle (cases 1-5) or a 120-mm 25-G Quincke needle (case 6) introduced via the 18-G needle. Sufentanil, 10 μg, diluted to 1 or 2 ml with preservative-free saline, was injected and the spinal needle withdrawn. A 20-G epidural catheter was threaded into the epidural space. In all cases, painless uterine contractions were achieved shortly after intrathecal injection. In cases 4-6, epidural test doses of 1.5% lidocaine with 1 :200,000 epinephrine 3 ml were administered at varying times after intrathecal injection. Cases 1-3 did not receive test doses. Specific details of the cases are described below.

Intrathecal Sufentanil Produces Sensory Changes without Hypotension in Male Volunteers

Background Intrathecally administered sufentanil is frequently associated with hypotension and sensory changes in women undergoing labor. In this study, the authors examined whether intrathecally administered sufentanil has similar effects in pain‐free individuals with low concentrations of progesterone (i.e., male volunteers). Methods Ten male volunteers were randomly assigned to received an intrathecal injection of either 10 [micro sign]g sufentanil or saline in a double‐blind fashion. Blood pressure, heart rate, oxyhemoglobin saturation, and temperatures from the body core and skin of the calf and ipsilateral great toe were recorded. Cold and pin prick sensation, motor block, and visual analogue scores for sedation, pruritus, and nausea also were assessed. Current perception thresholds using the Neurometer current perception threshold instrument (Neurotron, Inc., Baltimore, MD) were determined for three frequencies (2,000, 250, and 5 Hz, corresponding to stimulation of A[Greek small letter beta], A [partial difference], and C fibers, respectively) on the upper and lower extremities. Results Pruritus and sensory changes to pin prick and cold occurred in the sufentanil group but not the saline group. Neither group had a significant change in blood pressure, heart rate, oxyhemoglobin saturation, sedation, or core temperature. There was a clinically insignificant difference in the calf minus toe temperature index between the saline and sufentanil groups. There was a small increase in the current perception thresholds at 250 Hz in the sufentanil group. Conclusions Intrathecally administered sufentanil did not affect blood pressure in male volunteers. The other effects of sufentanil, however, were similar to those observed in women undergoing labor. This suggests that the hypotension occurring in these women after intrathecally administered sufentanil is secondary to relief of pain, rather than to a sympathectomy.

A comparison of the 24-gauge Sprotte and Gertie Marx spinal needles for combined spinal-epidural analgesia during labor.

BACKGROUND Prior experience with the combined spinal-epidural technique (CSE) for labor analgesia demonstrated a high (up to 14%) failure rate because of failure to obtain cerebrospinal fluid (CSF) or lack of response to appropriate doses of intrathecal sufentanil. The current study was designed to test whether a longer needle with a shorter side port (Gertie Marx needle; 127 mm long) would eliminate failures to obtain CSF compared with the needle we had used previously (Sprotte needle; 120 mm long). METHODS Seventy-three parturients were randomly assigned to have a CSE performed with one of these two needles. After identifying the epidural space with an 18-gauge Touhy needle at the L2-L3 or L3-L4 interspace, the spinal needle was introduced through the Touhy needle until penetration of the dura was felt or until the needle was maximally inserted. If no CSF was obtained, the alternate needle was tried. After obtaining CSF, 10 microg sufentanil diluted in 1.8 ml saline was injected. Verbal pain scores (0-10) were obtained every 5 min for 30 min. RESULTS Failure to obtain CSF occurred six times in the Sprotte group compared with none in the Gertie Marx group (P < 0.05). In all six failures in the Sprotte group, the Gertie Marx needle subsequently proved successful in obtaining CSF. There were no differences in pain scores between the groups. CONCLUSIONS The extra length of the 127-mm Gertie Marx needle resulted in a higher success rate for obtaining CSF when used in the CSE technique. Side port design was not a factor influencing success in this clinical setting.

Anesthesia for cesarean section in a pituitary dwarf.

PROVIDING anesthesia for parturient patients with dwarfism is an uncommon problem faced by anesthesiologists. We describe the anesthetic management for cesarean section in a patient with pituitary dwarfism.

Changes in the Position of Epidural Catheters Associated with Patient Movement

Background: Epidural catheter movement has been noted with change of patient position and can result in inadequate anesthesia. This study was designed to measure movement and to develop a technique that minimizes catheter displacement. Methods: In 255 parturients requesting epidural anesthesia for labor or cesarean section, a multiorificed lumbar epidural catheter was inserted with the patient in the sitting flexed position. The distance to the epidural space, length of catheter inserted, and amount of catheter position change as the patient moved from the sitting flexed to sitting upright and then to the lateral decubitus position were measured before the catheter was secured to the skin. Adequacy of analgesia, the need for catheter manipulation, and whether the patient was considered obese were noted. Data were grouped according to body mass index (BMI): < 25, 25–30, and > 30 kg/m2. Results: The groups did not differ with respect to the length of catheter initially inserted or changes in catheter position between initial taping and removal. The distance to the epidural space differed significantly among the groups, increasing with greater BMI. Catheters frequently appeared to be drawn inward with position change from the sitting flexed to lateral decubitus position, with the greatest change seen in patients with BMI > 30. Only nine catheters were associated with inadequate analgesia, four of which were replaced. No analgesic failures occurred in the BMI > 30 group. In patients judged by the anesthesiologist to be obese or to have an obese back, BMI was greater, and the distance to the epidural space and the magnitude of catheter movement with position change were greater than in those who were not obese. Conclusions: Epidural catheters moved a clinically significant amount with reference to the skin in all BMI groups as patients changed position. If catheters had been secured to the skin before position change, many would have been pulled partially out of the epidural space. To minimize the risk of catheter displacement, particularly in obese patients, we recommend that multiorificed catheters be inserted at least 4 cm into the epidural space and that patients assume the sitting upright or lateral position before securing the catheter to the skin.

Obstetric Postanesthesia Care Unit Stays Reevaluation of Discharge Criteria after Regional Anesthesia

Background Obstetric patients may have long postanesthesia care unit (OB‐PACU) stays after surgery because of residual regional block or other conditions. This study evaluated whether modified discharge criteria might allow for earlier discharge without compromising patient safety. Methods Data were prospectively collected for 6 months for all patients (N = 358) who underwent cesarean section or tubal ligation and recovered in the OB‐PACU. Regional anesthesia was used in 94% of patients. The duration of anesthesia and PACU stays, the presence and treatment of events in the PACU, and the regression of neural blockade were recorded. Discharge from the OB‐PACU required a 60‐min minimum stay, stable vital signs, adequate analgesia, and ability to flex the knees. After completion of prospective data collection, events that kept patients in the PACU after 60 min were reevaluated as to whether patients needed to stay in the PACU for medical reasons. “Needed to stay” events included bleeding, cardiorespiratory problems, sedation, dizziness, and pain. “Safe to leave” conditions included pruritus, nausea, and residual neural blockade. The cumulative duration of OB‐PACU stays not clearly justifiable for medical reasons was calculated. Results Residual block and spinal opioid side effects accounted for the majority of “unnecessary” stays. Annually, 429 h of PACU time could have been saved using the revised criteria. Complications did not develop subsequently in any patient deemed “safe to leave.” Conclusions In many obstetric patients, the duration of PACU stays could safely be shortened by continuing observation in a lower‐acuity setting. This may result in greater flexibility and more efficient use of nursing personnel.