Thoracic Spinal Anesthesia Research Articles

Ultrasound guided pectoral nerve blockade versus thoracic spinal blockade for conservative breast surgery in cancer breast: A randomized controlled trial

BackgroundBreast surgery is commonly performed in geriatric patients. In this age group, patients commonly suffer from comorbidities, making regional anesthesia the preferred option during surgery. Both segmental thoracic spinal anesthesia (TSA), thoracic paravertebral (TPB) and pectoral nerve (Pecs) blocks were tried successfully. This encouraged us to compare between segmental thoracic spinal anesthesia (TSA) and pectoral nerve (Pecs) block for surgeries in the thoracic region, namely breast surgery.MethodsForty (ASA) I–II patients aged between 40–65 years with cancer breast surgeries were enrolled in this study. In regard to anesthetic choice, patients were randomly divided into two groups, with 20 patients in each: Group A, with pectoral nerve block and group B, with thoracic spinal block. Standard monitoring in the form of mean blood pressure (MBP) and heart rate (HR) was recorded. Onset time for sensory block, time to reach peak sensory level, regression times of motor blocks and sensory blocks. Intraoperative VAS and post-operative VAS were recorded. Any postoperative complications such as bradycardia, hypotension, nausea and vomiting were assessed.ResultsThe time onset of both sensory and motor blocks was compared; there was statistically significant difference between both groups (P < 0.05). T1 was the highest level of sensory block attained at 17.7 ± 1.7 and 5.5 ± 1.6 min after injection in group A, and group B respectively and the total time for block was significantly prolonged in group A (940.3 ± 17.2 min) compared to group B (315.5 ± 44.3 min) as P ⩽ 0.0001. Regression times of motor blocks and sensory blocks, were significantly prolonged in group A (994 ± 55 min, 940 ± 34 min) compared to group B (382 ± 45 min, 351 ± 35 min) as P < 0.0001.Also, there was significant prolongation of duration of postoperative analgesia with significant reduction of total fentanyl requirement during the first 24 h postoperative in group A compared to group B.Regarding the hemodynamic variables (MBP, HR), there were significant decrease in HR and mean blood pressure (MBP) between the both groups throughout the intraoperative and early postoperative periods.ConclusionIn conclusion, both Pecs and TSB provide effective intraoperative anesthesia and prolonged postoperative pain relief after breast surgery, but the Pecs block is technically simple and easy to learn with few contraindications, provides hemodynamic stability, and has a low complication rate and it is therefore a safe and effective technique in performing intraoperative anesthesia and controlling postoperative pain after unilateral conservative breast surgery.

Thoracic combined spinal epidural anesthesia for laparoscopic cholecystectomy: A feasibility study.

Background and Aims:The use of regional anesthesia for laparoscopic cholecystectomy has been reserved for patients who are at high-risk under general anesthesia (GA). The aim of this study was to assess whether thoracic combined spinal epidural (CSE) anesthesia is a feasible option for American Society of Anesthesiologists (ASA) physical status I and II patients undergoing elective laparoscopic cholecystectomy.Material and Methods:Thirty ASA physical status I and II patients undergoing elective laparoscopic cholecystectomy received thoracic CSE anesthesia at T9-T10 or T10-T11 interspinous space using the midline approach. Two ml of isobaric levobupivacaine 0.5% with 25 μg of fentanyl was given intrathecally.Results:Surgery was conducted successfully in all except one patient. Thoracic CSE was performed at T9-T10 interspace in 25 patients and T10-T11 interspace in five patients. Paresthesia occurred in two patients (6.6%) transiently on Whitacre needle insertion that disappeared spontaneously. Dural puncture on epidural needle insertion occurred in one patient, and intrathecal placement of epidural catheter occurred in one. Ten patients (33%) complained of shoulder pain. Conversion to GA was done in one patient due to severe shoulder pain and anxiety. Hypotension occurred in 11 patients (36%) and all responded to single dose of mephenteramine 6 mg and fluid bolus. Bradycardia occurred in six patients (20%) which was managed in all with a single dose of atropine.Conclusion:Thoracic CSE anesthesia can be used effectively for ASA I and II patients undergoing laparoscopic cholecystectomy with significant postoperative benefits.

Thoracic combined spinal epidural anesthesia in patient of dilated cardiomyopathy undergoing laparoscopic cholecystectomy.

Thoracic combined spinal epidural anesthesia in patient of dilated cardiomyopathy undergoing laparoscopic cholecystectomy.

A comparison of thoracic spinal anesthesia with low-dose isobaric and low-dose hyperbaric bupivacaine for orthopedic surgery: A randomized controlled trial.

Background:The thoracic spinal anesthesia was first described in 1909 and recently revised for various surgical procedures. This is a prospective study aims to evaluate the parameters of the thoracic spinal anesthesia (latency, motor block and paresthesia), the incidence of cardiovascular changes and complications comparing low doses of isobaric and hyperbaric bupivacaine.Materials and Methods:A total of 200 orthopedic patients operated under spinal anesthesia were included in this study. Spinal anesthesia was between T9-T10, with a 27G cutting point or pencil tip in lateral or sitting. Spinal anesthesia was performed with 0.5% bupivacaine isobaric or hyperbaric. Patients remained in cephalad or head down position 10-20° for 10 minutes. We evaluated the demographics, analgesia, and degree of motor block, incidence of paresthesia, bradycardia, hypotension, anesthesia success and neurological complications.Results:All patients developed spinal and there was no failure. The solution did not affect the onset of the blockade. The duration of motor block was greater than the sensitive with isobaric. The duration of sensory block was greater than the motor block with hyperbaric solution. The incidence of paresthesia was 4%, with no difference between the needles. The incidence of hypotension was 12.5% with no difference between the solutions. There was no neurological damage in all patients.Conclusion:The beginning of the block is fast regardless of the solution used. By providing a sensory block of longer duration than the motor block hyperbaric bupivacaine is reflected in a better indication. Thoracic spinal anesthesia provides excellent anesthesia for lower limb orthopedic surgery

Thoracic spinal anesthesia is safe for patients undergoing abdominal cancer surgery.

Aim:A double-blinded randomized controlled study to compare discharge time and patient satisfaction between two groups of patients submitted to open surgeries for abdominal malignancies using segmental thoracic spinal or general anesthesia.Background:Open surgeries for abdominal malignancy are usually done under general anesthesia, but many patients with major medical problems sometimes can’t tolerate such anesthesia. Regional anesthesia namely segmental thoracic spinal anesthesia may be beneficial in such patients.Materials and Methods:A total of 60 patients classified according to American Society of Anesthesiology (ASA) as class II or III undergoing surgeries for abdominal malignancy, like colonic or gastric carcinoma, divided into two groups, 30 patients each. Group G, received general anesthesia, Group S received a segmental (T9-T10 injection) thoracic spinal anesthesia with intrathecal injection of 2 ml of hyperbaric bupivacaine 0.5% (10 mg) and 20 ug fentanyl citrate. Intraoperative monitoring, postoperative pain, complications, recovery time, and patient satisfaction at follow-up were compared between the two groups.Results:Spinal anesthesia was performed easily in all 30 patients, although two patients complained of paraesthesiae, which responded to slight needle withdrawal. No patient required conversion to general anesthesia, six patients required midazolam for anxiety and six patients required phenylephrine and atropine for hypotension and bradycardia, recovery was uneventful and without sequelae. The two groups were comparable with respect to gender, age, weight, height, body mass index, ASA classification, preoperative oxygen saturation and preoperative respiratory rate and operative time.Conclusion:This preliminary study has shown that segmental thoracic spinal anesthesia can be used successfully and effectively for open surgeries for abdominal malignancies by experienced anesthetists. It showed shorter postanesthesia care unit stay, better postoperative pain relief and patient satisfaction than general anesthesia.

The novel use of spinal anesthesia at the mid-thoracic level: a feasibility study

Background Breast surgery is commonly performed in geriatric patients. In this age group, patients commonly suffer from comorbidities, making regional anesthesia the preferred option during surgery. Recently, segmental thoracic spinal anesthesia for laparoscopic cholecystectomy was tried successfully. Anatomical studies showed that the posterior dural-spinal cord distance is wider at the mid-thoracic region. This encouraged us to test the feasibility of performing spinal anesthesia at the mid-thoracic level for surgeries in the thoracic region, namely breast surgery. Materials and methods We performed a prospective feasibility trial including 25 patients, American Society of Anesthesiologists-I (ASA-I), undergoing minor breast surgery (lumpectomy or simple mastectomy) under segmental thoracic spinal anesthesia at T5 level with 1 ml plain bupivacaine (5 mg/ml) and 0.3 ml fentanyl (50 μg/ml). We assessed the number of attempts required, paresthesia during needle insertion, sensory block level, need for supplemental analgesics or general anesthesia, and block-related complications. Hemodynamics as well as patient satisfaction were also recorded. Results The block was successful in all patients. A single insertion attempt was needed in 22 (88%) patients. No paresthesia was recorded during needle insertion. The upper sensory level was at T1 (T1-T2) and the lower sensory level at T11 (T11-T12). No additional analgesics or general anesthesia were needed during procedure. Four patients required ephedrine to correct hypotension. Two of these patients developed nausea during hypotension. No other complications were recorded. Total satisfaction was reported by 23 (92%) patients. Conclusion Segmental thoracic spinal anesthesia at T5 level in healthy patients undergoing breast surgery can be used successfully with minimal hemodynamic instability. The safety of this technique needs to be confirmed by further studies involving larger number of patients, with comorbid conditions, before it can be advised for routine use.

Spinal At T10 (10th Thoracic)

Background : The historical evidence of the use of “general spinal anesthesia” introduced by Thomas Jonnesco in 1909 for the surgeries of the skull, head, neck and thorax puncturing the subarachnoid space (SAS) between 1 st and 2 nd thoracic vertebra producing perfect and deep analgesia for the above mentioned area influenced to puncture SAS at 10 th thoracic vertebra (T10) in place of puncturing SAS between 12 th thoracic and 1 st lumbar vertebra proposed by Thomas Jonnesco for anesthesia of lower portion of the body including upper and lower abdomen. Method: 30 (thirty) patients of 59.23±7.219 years classified as ASA class 1 and 2 were selected for upper and lower abdominal surgeries by administration of lower thoracic spinal anesthesia at the level of T10 with 2.5 ml of 0.5% inj. bupivacaine at sitting position to each patient. Hypotensive episode was treated with increment doses of Mephentermine and anxiety of each patient was relieved with 2 mg of midazolam. Bradycardia was treated with inj. atropine. Supplemental oxygen was administered to each patient. Result: Intrathecal procedure was operated successfully at the level of T10 without neural damage and intraoperative fall of blood pressure (98.00±6.034) mm of Hg and pulse rate (55.87±3.636) beats/minute was observed in each case from their base value (117.4±15.741) mm of Hg and heart rate (84.53±12.451) beats / minute respectively. No change of oxygen concentration (Spo2) (98.77±0.817) % was observed in each case. Unchanged respiratory status maintained spo2 in normal range. Conclusion: With minimal hemodynamic instability and well controlled surgical stress response lower thoracic spinal anesthesia at the level of T10 is proposed to be good alternative technique to general anesthesia for open and laparoscopic surgeries in abdomen.

Comparative study between general and thoracic spinal anesthesia for laparoscopic cholecystectomy

BackgroundLaparoscopic cholecystectomy is usually done under general anesthesia, but many patients with major medical problems sometimes cannot tolerate such anesthesia, and thoracic spinal anesthesia may be beneficial in such patients. A comparative study between two groups of patients submitted to laparoscopic cholecystectomy using either general anesthesia or segmental thoracic spinal anesthesia.Patients and methodsForty patients classified according to American Society of Anesthesiology (ASA) as class I or II undergoing laparoscopic cholecystectomy, divided into two groups, 20 patients each. Group G received conventional general anesthesia with endotracheal intubation and mechanical ventilation, and group S received a segmental (T10-11 injection) thoracic spinal anesthesia (through combined spinal epidural) using 1 ml of plain bupivacaine 0.5% (5 mg) in addition to 25 μg fentanyl. In group S, drugs to manage patient anxiety or hemodynamic perturbations (bradycardia or hypotension) were given when needed. Intraoperative monitoring, postoperative pain, complications, recovery time, and patient satisfaction at follow-up were compared between the two groups.ResultsAs regards the thoracic spinal group, spinal anesthetic was performed easily in all 20 patients, although two complained of paresthesia, which responded to slight needle withdrawal; the block was effective for surgery in all 20 patients, and five experienced some discomfort, which was readily treated with small doses of fentanyl, but none required conversion to general anesthesia; five patients required midazolam for anxiety, eight patients required ephedrine and atropine for hypotension and bradycardia, and recovery was uneventful and without sequelae.AimThe aim of this study is to compare discharge time, patient, and surgeon satisfaction between two groups of healthy patients submitted to laparoscopic cholecystectomy under general and segmental thoracic spinal anesthesia.ConclusionPatients received segmental thoracic spinal anesthesia had shorter discharge time and better satisfaction. Surgeon satisfaction was higher in general anesthesia group. Segmental thoracic spinal anesthesia can be used successfully and effectively for laparoscopic cholecystectomy in healthy patients by experienced anesthetists.

Segmental thoracic spinal has advantages over general anesthesia for breast cancer surgery.

Background:Thoracic spinal anesthesia has been used for laparoscopic cholecystectomy and abdominal surgeries, but not in breast surgery. The present study compared this technique with general anesthesia in breast cancer surgeries.Materials and Methods:Forty patients were enrolled in this comparative study with inclusion criteria of ASA physical status I-III, primary breast cancer without known extension beyond the breast and axillary nodes, scheduled for unilateral mastectomy with axillary dissection. They were randomly divided into two groups. The thoracic spinal group (S) (n = 20) underwent segmental thoracic spinal anesthesia with bupivacaine and fentanyl at T5-T6 interspace, while the other group (n = 20) underwent general anesthesia (G). Intraoperative hemodynamic parameters, intraoperative complications, postoperative discharge time from post-anesthesia care unit (PACU), postoperative pain and analgesic consumption, postoperative adverse effects, and patient satisfaction with the anesthetic techniques were recorded.Results:Intraoperative hypertension (20%) was more frequent in group (G), while hypotension and bradycardia (15%) were more frequent in the segmental thoracic spinal (S) group. Postoperative nausea (30%) and vomiting (40%) during PACU stay were more frequent in the (G) group. Postoperative discharge time from PACU was shorter in the (S) group (124 ± 38 min) than in the (G) group (212 ± 46 min). The quality of postoperative analgesia and analgesic consumption was better in the (S) group. Patient satisfaction was similar in both groups.Conclusions:Segmental thoracic spinal anesthesia has some advantages when compared with general anesthesia and can be considered as a sole anesthetic in breast cancer surgery with axillary lymph node clearance.

General anesthesia versus segmental thoracic or conventional lumbar spinal anesthesia for patients undergoing laparoscopic cholecystectomy.

Background:Laparoscopic cholecystectomy became the standard surgery for gallstone disease because of causing less postoperative pain, respiratory compromise and early ambulation.Objective:This study was designed to compare spinal anesthesia, (segmental thoracic or conventional lumbar) vs the gold standard general anesthesia as three anesthetic techniques for healthy patients scheduled for elective laparoscopic cholecystectomy, evaluating intraoperative parameters, postoperative recovery and analgesia, complications as well as patient and surgeon satisfaction.Materials and Methods:A total of 90 patients undergoing elective laparoscopic cholecystectomy, between January 2010 and May 2011, were randomized into three equal groups to undergo laparoscopic cholecystectomy with low-pressure CO2 pneumoperitoneum under segmental thoracic (TSA group) or conventional lumbar (LSA group) spinal anesthesia or general anesthesia (GA group). To achieve a T3 sensory level we used (hyperbaric bupivacaine 15 mg, and fentanyl 25 mg at L2/L3) for LSAgroup, and (hyperbaric bupivacaine 7.5 mg, and fentanyl 25 mg at T10/T11) for TSAgroup. Propofol, fentanyl, atracurium, sevoflurane, and tracheal intubation were used for GA group. Intraoperative parameters, postoperative recovery and analgesia, complications as well as patient and surgeon satisfaction were compared between the three groups.Results:All procedures were completed laparoscopically by the allocated method of anesthesia with no anesthetic conversions. The time for the blockade to reach T3 level, intraoperative hypotensive and bradycardic events and vasopressor use were significantly lower in (TSA group) than in (LSA group). Postoperative pain scores as assessed throughout any time, postoperative right shoulder pain and hospital stay was lower for both (TSA group) and (LSA group) compared with (GA group). The higher degree of patients satisfaction scores were recorded in patients under segmental TSA.Conclusion:The present study not only confirmed that both segmental TSA and conventional lumber spinal anesthesia (LSA) are safe and good alternatives to general anesthesia (GA) in healthy patients undergoing laparoscopic cholecystectomy but also showed better postoperative pain control of both spinal techniques when compared with general anesthesia. Segmental TSA provides better hemodynamic stability, lesser vasopressor use and early ambulation and discharge with higher degree of patient satisfaction making it excellent for day case surgery compared with conventional lumbar spinal anesthesia.

Laparoscopic cholecystectomy under spinal anesthesia: comparative study between conventional-dose and low-dose hyperbaric bupivacaine.

BackgroundLaparoscopic cholecystectomy has the advantages of causing less postoperative pain and requiring a short hospital stay, and therefore is the treatment of choice for cholelithiasis. This study was designed to compare spinal anesthesia using hyperbaric bupivacaine given as a conventional dose by lumbar puncture or as a low-dose by thoracic puncture.MethodsA total of 140 patients with symptomatic gallstone disease were randomized to undergo laparoscopic cholecystectomy with low-pressure CO2 pneumoperitoneum under spinal anesthesia using either conventional lumbar spinal anesthesia (hyperbaric bupivacaine 15 mg and fentanyl 20 mg) or low-dose thoracic spinal anesthesia (hyperbaric bupivacaine 7.5 mg and fentanyl 20 μg). Intraoperative parameters, postoperative pain, complications, recovery time, and patient satisfaction at follow-up were compared between the two treatment groups.ResultsAll procedures were completed under spinal anesthesia, with no cases needing conversion to general anesthesia. Values for time for block to reach the T3 dermatomal level, duration of motor and sensory block, and hypotensive events were significantly lower with low-dose bupivacaine. Postoperative pain was higher for low-dose hyperbaric bupivacaine at 6 and 12 hours. All patients were discharged after 24 hours. Follow-up 1 week postoperatively showed all patients to be satisfied and to be keen advocates of spinal anesthesia.ConclusionLaparoscopic cholecystectomy can be performed successfully under spinal anesthesia. A small dose of hyperbaric bupivacaine 7.5 mg and 20 μg fentanyl provides adequate spinal anesthesia for laparoscopy and, in comparison with hyperbaric bupivacaine 15% and fentanyl 20 μg, causes markedly less hypotension. The low-dose strategy may have an advantage in ambulatory patients because of the earlier recovery of motor and sensory function and earlier discharge.

The Incidence of Paresthesia and Neurologic Complications after Lower Spinal Thoracic Puncture with Cut Needle Compared to Pencil Point Needle. Study in 300 Patients

Background: Anesthesiologists are reluctant to considerer higher levels for spinal anesthesia largely due to direct threats to spinal cord. Paresthesias are relatively common during spinal needle insertion; however, the clinical significance of the paresthesia is unknown. The main objective of this prospective study was to evaluate the incidence of paresthesia and neurologic complications after lower thoracic spinal anesthesia with a cut needle compared to a pencil point needle. Methods: Low thoracic spinal puncture (T10-T11) was performed in 300 patients in elective surgery using different techniques in this single-blind prospective trial. Patients randomized to 2 groups: group 1, subarachnoid puncture using a cut needle without introducer and group 2, subarachnoid puncture using a pencil point needle with introducer. In both groups patients were in the lateral or sitting position. Results: Paresthesias occurred in 20/300 (6.6%) of patients. Seven patients experienced a paresthesia with cut needle compared with 13 patients with pencil point, without statistical difference. All paresthesias were transient. No neurologic complications were observed in all patients during this study. Conclusions: Our data suggest that all transient paresthesia are transitory. Lower thoracic puncture is safe. Traumatic injury to the spinal cord is a rare cause of neurologic deficits in the thoracic puncture.

Laparoscopic cholecystectomy performed under regional anesthesia in patient who had undergone pneumonectomy: A case report.

Seventy-one years old, ASA physical status III, male patient underwent laparoscopic cholecystectomy due to acute cholecystitis with gall bladder (GB stone). He had undergone right pneumonectomy nine years ago. Moderate obstructive and restrictive pattern was found on PFT and hypokinesia of apical anterior and septum segments was seen on echocardiography. Due to patient's refusal of receiving general anesthesia, we decided to perform regional anesthesia. Epidural catheter was inserted at 10th thoracic intervertebral space and segmental spinal anesthesia was performed at L2-L3 intervertebral space with 5 mg of hyperbaric bupivacaine 0.5% and 20 ug of fentanyl. A segmental sensory block, extending from T3 through L2 dermatomes, was obtained. Surgery was performed smoothly and uneventfully. Patient discharged from hospital at 3 days after surgery.

Comments about thoracic spinal anesthesia for gastrostomy

Comments about thoracic spinal anesthesia for gastrostomy

Thoracic spinal anesthesia for gastrostomy in a patient with severe lung disease

Thoracic spinal anesthesia for gastrostomy in a patient with severe lung disease

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 L 3–L 4 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 T 8. 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.

Infants Tolerate Spinal Anesthesia with Minimal Overall Autonomic Changes

Unlike adults, neonates tolerate high thoracic spinal anesthesia with minimal changes in heart rate (HR) and arterial blood pressure. To examine the potential autonomic regulatory mechanisms which may account for these findings, the relation between short-term heart rate variability (HRV) and respiratory activity was analyzed in a group of eight ASA grade II former premature infants undergoing high thoracic spinal anesthesia for inguinal hernia repairs. Quantitative measures of sympathetic (As) and parasympathetic (Ap) modulation of HR were derived. HR, arterial blood pressure, and a calibrated respiratory signal were recorded during 4.4-min stable epochs in eight subjects 1) preoperatively, 2) postincision after high thoracic spinal anesthesia, and 3) during an active sleep state in the postoperative period. Power spectral analysis of HRV and respiratory power yielded measures of low-frequency power (LFP: 0.02-0.15 Hz) and high-frequency power (HFP: 0.15-0.8 Hz). Transfer function analysis between respiratory activity and HR were used to quantify As and Ap. All subjects had successful high thoracic spinal anesthesia with highest levels ranging from C7-T4. Mean HR, blood pressure, and respiratory power did not change significantly with high thoracic spinal anesthesia. LFP and HFP both decreased significantly, whereas the LFP/HFP ratio remained stable. Group mean As and Ap both decreased, but the changes were not significant. Despite overall cardiovascular stability, HRV decreased with high thoracic spinal anesthesia, but the balance between LFP and HFP remained stable, suggesting that the reflex response to high thoracic spinal anesthesia was predominantly diminished parasympathetic modulation of cardiac function. The expected decrease in HR and blood pressure from the sympatholysis which results from high thoracic spinal anesthesia were apparently offset by withdrawal of cardiac vagal activity.

Infants Tolerate Spinal Anesthesia with Minimal Overall Autonomic Changes

Unlike adults, neonates tolerate high thoracic spinal anesthesia with minimal changes in heart rate (HR) and arterial blood pressure.To examine the potential autonomic regulatory mechanisms which may account for these findings, the relation between short-term heart rate variability (HRV) and respiratory activity was analyzed in a group of eight ASA grade II former premature infants undergoing high thoracic spinal anesthesia for inguinal hernia repairs. Quantitative measures of sympathetic (As) and parasympathetic (Ap) modulation of HR were derived. HR, arterial blood pressure, and a calibrated respiratory signal were recorded during 4.4-min stable epochs in eight subjects 1) preoperatively, 2) postincision after high thoracic spinal anesthesia, and 3) during an active sleep state in the postoperative period. Power spectral analysis of HRV and respiratory power yielded measures of low-frequency power (LFP: 0.02-0.15 Hz) and high-frequency power (HFP: 0.15-0.8 Hz). Transfer function analysis between respiratory activity and HR were used to quantify As and A (p). All subjects had successful high thoracic spinal anesthesia with highest levels ranging from C7-T4. Mean HR, blood pressure, and respiratory power did not change significantly with high thoracic spinal anesthesia. LFP and HFP both decreased significantly, whereas the LFP/HFP ratio remained stable. Group mean As and Ap both decreased, but the changes were not significant. Despite overall cardiovascular stability, HRV decreased with high thoracic spinal anesthesia, but the balance between LFP and HFP remained stable, suggesting that the reflex response to high thoracic spinal anesthesia was predominantly diminished parasympathetic modulation of cardiac function. The expected decrease in HR and blood pressure from the sympatholysis which results from high thoracic spinal anesthesia were apparently offset by withdrawal of cardiac vagal activity. (Anesth Analg 1995;80:20-7)

Effect of Spinal Anesthesia on Adrenergic Tone and the Neuroendocrine Responses to Surgical Stress in Humans

In order to quantitate the effect of spinal anesthesia on adrenergic tone, plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured by radioenzymatic assay in 24 patients were then compared to those of 10 patients receiving inhalation anesthesia (halothane-nitrous oxide). High thoracic dermatome spinal anesthesia caused suppression of both arterial plasma NE and EPI and a fall of mean arterial pressure (MAP); in contrast, no changes of NE, EPI, or MAP were observed in patients receiving low spinal anesthesia. Overall, there was a relationship between the sensory dermatome anesthesia level and changes of both plasma NE (r = 0.71, P less than 0.001) and EPI (r = 0.52,P less than 0.02). In the inhalation anesthesia group, plasma NE increased during the operation and plasma levels of NE, EPI, growth hormone, and cortisol were elevated during the postoperative recovery period. These neuroendocrine responses to surgical stress were not observed in patients receiving either low or high spinal anesthesia. Thus, the effect of spinal anesthesia on adrenergic tone depends on the cord level of anesthesia and can be quantitated by measurement of plasma catecholamines. The neuroendocrine responses to surgical stress were prevented in patients who received low spinal anesthesia and who had no suppression of efferent adrenergic tone. These findings indicate that neural afferents from the site of tissue injury, which were blocked by low spinal anesthesia, mediated both the adrenergic and the hormonal responses to surgical stress in the inhalation anesthesia group.