Helen J. Yoon

Spinal anesthesia for elective lumbar spine surgery

STUDY OBJECTIVE To evaluate a large series of elective lumbar spine surgical procedures by a single surgeon whose patients were all offered spinal anesthesia. DESIGN Retrospective chart review. SETTING Tertiary-care teaching hospital. MEASUREMENTS AND MAIN RESULTS The records of all elective lumbar spine procedures between 1984 and 1995 performed by one surgeon (GRB) were obtained, and 803 were identified. Of those 803 patients, 611 accepted spinal anesthesia. Data collected included patient demographics, details of the spinal and general anesthesia, perioperative complications, and impact of the spinal anesthetic options on the outcome of spinal anesthesia. General and spinal anesthesia patients were comparable for age, gender, height, and ASA physical status. Patients who received spinal anesthesia were significantly heavier than the general anesthesia patients. Among perioperative complications, nausea and deep venous thrombosis occurred significantly more often in the general than spinal anesthesia patients. Mild hypotension and decreased heart rate (HR) were the most common hemodynamic changes with spinal anesthesia, whereas hypertension and increased HR were the result of general anesthesia. Among spinal anesthetic drugs, plain bupivacaine was associated with the lowest incidence of supplemental local anesthetic use intraoperatively compared to hyperbaric bupivacaine or hyperbaric tetracaine. CONCLUSION Spinal anesthesia is an effective alternative to general anesthesia for lumbar spine surgery and has a reduced rate of minor complications.

Effectiveness of bupivacaine administered via femoral nerve catheter for pain control after anterior cruciate ligament repair

STUDY OBJECTIVE To evaluate the quality of pain control achieved with continuous local anesthetic infusion via a femoral nerve catheter, and to determine the optimum concentration of bupivacaine necessary to maintain pain control after full surgical anesthesia is established with 0.5% bupivacaine. DESIGN Randomized, prospective study. SETTING Tertiary care teaching center. PATIENTS 25 ASA physical status I and II patients scheduled to undergo arthroscopically-aided anterior cruciate ligament (ACL) reconstruction by one surgeon, and who were willing to accept a femoral nerve catheter for postoperative pain control. INTERVENTIONS All patients received general anesthesia with propofol/alfentanil (10 ml/1 ml) mixture and nitrous oxide/oxygen (60%/40%) mixture via endotracheal tube. After induction of general anesthesia, a femoral nerve catheter was inserted with the aid of a nerve stimulator, and 20 ml of 0.5% bupivacaine was administered. The surgery was completed in a standard manner and the patients were randomized into three groups for the concentration of local anesthetic to continue the pain relief into the recovery phase. On awakening, all patients were determined to have a functioning femoral nerve catheter. Group 1 received 0.0625% (n = 8) bupivacaine, Group 2 0.125% (n = 9) bupivacaine, and Group 3 0.25% (n = 8) bupivacaine; all doses were initiated in a blinded manner at 0.12 ml/kg/hr. Patients also received intravenous patient-controlled analgesia with morphine via demand mode only, with a 1.0 mg dose and a 6 minute lock-out interval. MEASUREMENTS AND MAIN RESULTS Pain was determined at defined intervals by visual analog scale (VAS). Data collected included demographics, VAS scores, and total morphine administered. All patients were pain-free on emergence from general anesthesia. No patient required parenteral opioid for pain control while in the postanesthesia care unit. There were no significant differences in pain scores among groups, and average pain scores (2.5 to 4.0) indicate good pain control throughout the entire hospitalization. There were no complications. CONCLUSIONS Low concentrations of bupivacaine delivered via femoral nerve catheter after an established femoral nerve block can provide excellent postoperative pain control after ACL reconstruction.

Complications associated with lumbar laminectomy: a comparison of spinal versus general anesthesia.

Study Design. A case-controlled, comparative study of 400 patients undergoing lumbar surgery, treated with either spinal or general anesthesia. An independent observer analyzed outcomes. Objectives. To determine the rate and type, of perioperative complications associated with each anesthetic method among lumbar surgery patients. Summary of Background Data. Spinal anesthesia is infrequently used for spinal procedures. While complications associated with spinal anesthesia are rare, some authors have suggested that spinal anesthesia may exacerbate existing neurologic disease and have recommended against its use in lumbar disc surgery. Others have found the technique safe and effective. General anesthesia may be preferred because it is seen as the routine accepted practice, because of greater patient acceptance and the ability to perform longer operations, or because of a general sense that general anesthesia is “safer” in these procedures. Methods. Patients treated between 1994 and 1998 were matched for anesthetic class, preoperative diagnosis, surgical procedure, and perioperative protocols. All patients were treated according to a uniform protocol and recovered in the same perianesthetic environment. Data from the intraoperative period through hospital discharge were collected and compared. Results. A total of 200 patients were included in each group. Overall complication rates and time to discharge were significantly lower in spinal anesthetic patients. Total anesthetic and operative times were significantly longer for general anesthetic patients, and perioperative heart rate and mean arterial pressures were elevated compared with those in spinal anesthetic patients. Nausea, requirements for antiemetic medication, and the incidence of urinary retention were significantly increased among general anesthesia patients. Spinal anesthesia patients had fewer spinal headaches compared with the general anesthetic group, but statistical significance was not obtained. Conclusions. For patients undergoing decompressive lumbar surgery, spinal anesthesia is at least comparable to general anesthetic with respect to complications. Specific advantages to spinal anesthesia include decreased nausea and antiemetic requirements, reduced analgesic requirements, and reduced overall complication rate.

Tourniquet-induced hypertension correlates with autonomic nervous system changes detected by power spectral heart rate analysis

STUDY OBJECTIVE To determine the autonomic changes associated with pneumatic tourniquet-induced hypertension as measured by power spectral heart rate analysis (PSHR). DESIGN Prospective study. SETTING Tertiary teaching hospital. PATIENTS 21 healthy-patients scheduled for lower extremity surgery, during which pneumatic tourniquet inflation was expected to exceed 90 minutes. INTERVENTIONS Hemodynamic and PSHR data collected at 5 minute intervals during inflation of the pneumatic tourniquet. Tourniquet-induced hypertension (T-HTN) defined at 30% increase above baseline. MEASUREMENTS AND MAIN RESULTS Blood pressure, heart rate, maximum changes in low frequency variability (LFa), high frequency variability (HFa), and their ratio (LFa/HFa) were measured. Of the 21 patients, 11 had T-HTN. A significantly greater increase in LFa and LFa/HFa ratio was seen in the T-HTN group, where patients were greater in age. LFa, HFa, and ratio were not significantly different with T-HTN until 60 minutes or greater. Best correlation with T-HTN occurred with maximum increase in LFa/HFa ratio compared with increase in LFa or decrease in HFa. CONCLUSION Tourniquet hypertension correlated with activation of the sympathetic nervous systems, as measured by PSHR variables.

Heart Rate Variability and the Prone Position under General versus Spinal Anesthesia

Abstract Study Objective: To evaluate heart rate (HR) variability in the prone position with power spectral heart rate (PSHR) analysis during spinal and general anesthesia. Design: Prospective, clinical evaluation of HR variability in the prone position. Setting: Tertiary care teaching hospital. Patients: 20 healthy, ASA physical status I and II patients scheduled for elective lumbar spine surgery in the prone position. Interventions: Anesthetic technique was either a standard general anesthetic or spinal anesthetic, based on the preference of the patient. Power spectral heart rate, HR, and blood pressure (BP) readings were determined prior to anesthetic intervention and as soon as a stable PSHR reading was available in the prone position. Measurements and Main Results: Heart rate and BP were recorded at baseline prior to anesthesia and at the time of stable PSHR data in the prone position. Power spectral heart rate data included low-frequency activity (LFa), high-frequency activity (HFa), and the ratio (LFa/HFa). Spinal anesthesia level was recorded by thoracic dermatome at complete onset. Data were collected from 20 patients; 12 patients chose spinal anesthesia and 8 chose general anesthesia. The prone position resulted in significant increase in HR in the spinal group and significant decrease in BP in the general anesthesia group. Low-frequency activity and LFa/HFa ratio were unchanged in the spinal anesthesia group and were significantly decreased in the general anesthesia group. Spinal level was T8.7. Conclusions: The association of less change in LFa activity and preservation of BP on assumption of the prone position in patients during low spinal anesthesia suggests better preservation of autonomic nervous system compensatory mechanisms during low spinal anesthesia than with general anesthesia.

Massive bleeding during spine surgery in a patient with ankylosing spondylitis

PurposeAnkylosing spondylitis is associated with pathophysiology that has important anaesthetic implications. We report a case where the sequelae of ankylosing spondylitis may have been responsible for massive bleeding during emergency spine surgery.Clinical FeaturesA 69 yr old man with long standing ankylosing spondylitis sustained a complex fracture of the lumbar spine in a fall, and was scheduled for stabilization of the spine. Under general anaesthesia, prone positioning was difficult because of the extreme spinal deformity. During exploration, dilatation of epidural veins was encountered and sustained haemorrhage was encountered throughout,the surgical procedure. Estimated blood loss was 17,000 ml which was replaced with 31 units of packed red blood cells, 3200 ml of salvaged blood, 18 units of fresh frozen plasma, 26 units of platelets, 1,000 ml of albumin and 9,000 ml of crystalloid.ConclusionsExtreme deformity of the spine led to positioning difficulties that may have contributed to massive blood loss during complex spine surgery. Difficulties with placement in the prone position in-patients with advanced ankylosing spondylitis should be anticipated.RésuméObjectifLa spondylarthrite ankylosante est associée à la physiopathologie ayant d’importantes implications anesthésiques. Nous rapportons un cas où les séquelles de la spondylarthrite ankylosante peuvent avoir été responsables d’un saignement abondant pendant une chirurgie d’urgence de la colonne vertébrale.Aspects cliniquesUn homme de 69 ans, atteint de spondylarthrite ankylosante depuis longtemps, a subi lors d’une chute une fracture complexe de la colonne lombaire pour laquelle on a programmé une stabilisation. Pendant l’anesthésie générale, l’importante déformation de la colonne a compliqué l’installation en décubitus ventral. Lors de l’exploration, on a dû faire face à la dilatation des veines péridurales et à une hémorragie, qui s’est prolongée pendant toute la durée de l’intervention. La perte sanguine, estimée à 17 000 ml, a été compensée par 31 unités de globules rouges concentrés, 3 200 ml de sang récupéré, 18 unités de plasma frais congelé, 26 unités de plaquettes, 1000 ml d’albumine et 9 000 ml de cristalloïdes.ConclusionL’importante déformation de la colonne vertébrale a compliqué l’installation du patient, ce qui a pu contribuer à des pertes sanguines abondantes pendant une chirurgie complexe de la colonne. Des difficultés d’installation en décubitus ventral sont à prévoir avec un patient hospitalisé souffrant de spondylarthrite ankylosante avancée.

Regional anaesthetic technique and the incidence of tourniquet pain

The influence of regional anaesthetic technique on the incidence of lower extremity tourniquet pain was evaluated. We studied 60 patients undergoing orthopaedic procedures of the lower extremity with the use of a pneumatic tourniquet and anticipated inflation of 60 min or longer. Three different anaesthetic techniques were selected by random card draw: spinal anaesthesia (SAB) with plain 0.5% bupivacaine (15 mg) and 0.2 mg epinephrine added, lumbar epidural anaesthesia (EA) with 2% mepivacaine and 1:200,000 epinephrine added, and epidural anaesthesia (AEA) with the same solution alkalinized with bicarbonate. Onset and level of sensory blockade were determined by loss of painful sensation to pinprick. The incidence of tourniquet pain was determined at 15-min intervals or by patient complaint, by an observer unaware of group. Time to onset of pain, amount of treatment (iv fentanyl), and sensory level at the time of pain were determined. The SAB was compared with EA and AEA, and EA was compared with AEA. The SAB group was older. The sensory level achieved and duration of tourniquet inflation did not differ among groups. The incidence of tourniquet pain was lower with SAB than with EA and lower with AEA than with EA. There was no difference between SAB and AEA. This study demonstrated a lower incidence of tourniquet pain with spinal anaesthesia than with epidural anaesthesia to the same sensory level. However, this advantage is eliminated if the epidural anaesthetic was performed with an alkalinized local anaesthetic.RésuméNous avons évalué l’influence des techniques d’anesthésie régionale sur la douleur causée par un garrot au niveau du membre inférieur. Nous avons étudié 60 patients subissant une intervention orthopédique du membre inférieur avec utilisation d’un garrot pneumatique prévu pour 60 minutes ou plus. Trois techniques anesthésiques différentes ont été utilisées aléatoirement: anesthésie rachidienne (AR) avec de la bupivacaine 0,5% (15 mg) adrénalinée extemporanément à une concentration de 1:200 000, anesthésie épidurale lombaire (AE) avec 2% mépivacaine et 1:200000 d’adrénaline et anesthésie épidurale avec la même solution mais alcalinisée au bicarbonate (AEA). Le début et le niveau du bloc sensitif sont déterminés par la perte de sensation à la piqure. L’incidence de la douleur du garrot a été évaluée à 15 minutes d’intervalle ou en cas de plainte du patient par un observateur ignorant la technique d’anesthésie. Le délai d’apparition de la douleur, l’importance du traitement (Fentanyl iv) et le niveau sensitif au moment des plaintes ont été notés. L’AR est comparée à l’AE et à l’AEA, et l’AE est comparée à l’AEA. Le groupe AR se compose de patients plus âgés. Le niveau sensitif du bloc obtenu et la durée du garrot sont semblables dans tous les groupes. L’incidence de la douleur due au garrot est plus basse avec l’AR par rapport à l’AE, et plus basse avec l’AEA qu’avec l’AE. Il n’y a pas de différence entre l’AR et l’AEA. Cette étude démontre une incidence plus basse de douleur due au garrot avec l’anesthésie rachidienne qu’avec l’anesthésie épidurale pour un même niveau de bloc sensitif. Cependant, cet avantage de l’AR est perdu si l’anesthésie épidurale se réalise avec un anesthésique local alcalinisé.

Efficacy of Intermittent Epidural Morphine Following Posterior Spinal Fusion in Children and Adolescents

Postoperative pain is a distressing and disabling feature of scoliosis surgery. Epidural morphine has recently been advocated to reduce the frequency and severity of postoperative pain in adults. A retrospective study of 35 patients was conducted to determine whether epidural administration of morphine is useful in the management of postoperative pain in children and adolescents following posterior spinal fusion. The derived data included dose and frequency of narcotic administration on the day of surgery and during the subsequent three days. On the first postoperative day, the total morphine given averaged only 16.4 mg in patients receiving epidural morphine compared to 27 mg in those receiving only conventional parenteral morphine. Similar significant differences persisted through the second postoperative day. Intermittent epidural injection of small doses of morphine can give satisfactory and prolonged analgesia for early postoperative pain management.

pH adjustment of mepivacaine decreases the incidence of tourniquet pain during axillary brachial plexus anaesthesia

The effect of pH adjustment of mepivacaine on the incidence of tourniquet pain during axillary brachial plexus anaesthesia was studied. Thirty-nine patients scheduled for hand surgery, during which use of pneumatic tourniquet for longer than 60 min was planned, were randomized into two groups. Both received axillary brachial plexus block with 40 ml, 1.4% mepivacaine, 1:200,000 epinephrine. The study group had 4 ml sodium bicarbonate (1 mEq · ml− 1) added (final pH 7.31), and the control group had 4 ml saline added (final pH 5.6). The incidence of tourniquet pain was determined from cases for which tourniquet inflation lasted longer than 60 min. Tourniquet; pain was defined as poorly localized and distinct from an inadequate axillary block by a blinded observer. More tourniquet pain occurred in the control group. The authors conclude that alkalinization of mepivacaine for axillary brachial plexus anaesthesia may be indicated in cases where use of pneumatic tourniquet for long periods is planned.RésuméCe travail étudie les effets de l’adjustement du pH de la mépi-vacaïne sur l’incidence des douleurs causées par le garrot pendant l’anesthésie du plexus brachial par vole axillaire. Trenteneuf patients programmés pour une chirurgie de la main au cours de laquelle un garrot gonflé pourrait être en place pour plus de soixante minutes, sont répartis au hasard entre deux groupes. Les patients des deux groupes recoivent un block axillaire realise avec 40 ml de mépivacaïne 1,4% adrénalinée à 1:200,000. Pour le groupe d’étude, on ajoute à cette solution du bicarbonate de soude 4 ml (1 mEq · ml− 1) pour obtenir un pH de 7,31; pour le groupe contrôle, du soluté physiologique 4 ml pour un pH de 5,6. L’incidence des douleurs causées par le garrot est déterminée dans les cas où l’insufflation du garrot dure plus de 60 min. Un observateur neutre définit la douleur du garrot par une douleur mal localisée et distincte de celle d’un block sensoriel incomplet. La douleur du garrot est plus intense dans le groupe contrôle. Les auteurs concluent que l’al-calinisation de la mépivacaïne pour le block axillaire pourrait être indiquée lorsqu’on prévoit des durées d’insufflation de garrot dépassant soixante minutes.

Power Spectral Heart Rate Analysis Demonstrates Decreased Activity of the Sympathetic Nervous System During Low Bupivacaine Spinal Anesthesia

STUDY OBJECTIVE To evaluate the onset of spinal anesthesia with power spectral heart rate analysis to determine the influence of the block on the autonomic nervous system. DESIGN Prospective, clinical evaluation. SETTING Tertiary-care teaching hospital. PATIENTS 27 ASA physical status I and II patients scheduled for lower extremity orthopedic surgery and free of major cardiac disease or cardiac drugs with direct influence of heart rate (HR) or blood pressure (BP). INTERVENTIONS Prior to anesthesia, a baseline power spectral heart rate reading was taken in the supine position. Spinal anesthesia was established in the sitting position with 15 mg of bupivacaine and 0.2 mg epinephrine introduced at the L3-L4 interspace with a 22-gauge Quincke needle. The patient was returned supine, and power spectral heart rate data were again collected at 5-minute intervals throughout the procedure. Level of the spinal block was checked at 5-minute intervals until 30 minutes and considered complete when two consecutive readings were unchanged. MEASUREMENTS AND MAIN RESULTS Heart rate and BP were recorded at baseline and at five-minute intervals after injection. Power spectral heart rate data included low-frequency activity (LFa), high-frequency activity (HFa), and the ratio (LFa/HFa). Spinal level achieved was recorded by thoracic dermatome at complete onset. Heart rate and BP remained within 20% of control in all cases. Complete onset of the spinal block was present by 30 minutes in all cases. The average level of spinal anesthesia was T8. Compared with baseline, LFa activity decreased, HFa activity remained unchanged, and the ratio was decreased. During endoprosthesis insertion, 9 of 14 total hip patients had a transient ten-fold increase in LFa activity, without HFa change, and a corresponding increase in the ratio. CONCLUSIONS Power spectral heart rate analysis during low thoracic bupivacaine spinal anesthesia is compatible with decreased sympathetic activity during stable hemodynamic intervals. Insertion of hip endoprosthesis resulted in a dramatic, transient increase in sympathetic activity, indicating that sympathetic activation was still possible despite the presence of surgical anesthesia from the subarachnoid block.