Severe hypothermia associated with cesarean section under spinal anesthesia

Temperature monitoring and prevention of hypothermia are rarely used during spinal anaesthesia for caesarean section because hypothermia risk is considered very low. However, in same conditions, we observed two cases of severe hypothermia. We report these two cases and discuss the effects of spinal anaesthesia on thermoregulatory system. Hypothermia seems explained by the effects of perimedullar anaesthesia that decrease the shivering and the vasoconstriction thresholds. These effects are potentiated by morphinomimetic adjunction. At last, we recall prophylactics measures.     

Sedation during spinal anesthesia

BACKGROUND: Central neuraxial anesthesia has been reported to decrease the dose of both intravenous and inhalational anesthetics needed to reach a defined level of sedation. The mechanism behind this phenomenon is speculated to be decreased afferent stimulation of the reticular activating system. The authors performed a two-part study (nonrandomized pilot study and a subsequent randomized, double-blind, placebo-controlled study) using the Bispectral Index (BIS) monitor to quantify the degree of sedation in unmedicated volunteers undergoing spinal anesthesia. METHODS: Twelve volunteers underwent BIS monitoring and observer sedation scoring (Observer's Assessment of Alertness/Sedation Scale [OAA/S]) before and after spinal anesthesia with 50 mg hyperbaric lidocaine, 5%. Subsequently, 16 volunteers blinded to the study were randomized to receive spinal anesthesia with 50 mg hyperbaric lidocaine, 5% (n = 10) or placebo (n = 6) and underwent BIS and OAA/S monitoring. RESULTS: In part I, significant changes in BIS scores of the volunteers occurred progressively (P = 0.003). The greatest variations from baseline BIS measurement occurred at 30 and 70 min. In part II, there were significant decreases in OAA/S and self-sedation scores for patients receiving spinal anesthesia versuscontrol patients (P = 0.04 and 0. 01, respectively). The greatest decrease in OAA/S scores occurred at 60 min. BIS scores were similar between groups (P = 0.4). CONCLUSIONS: Spinal anesthesia is accompanied by significant sedation progressively when compared with controls as measured by OAA/S and self-sedation scores. This effect was not related to block height. The late sedation observed by OAA/S at 60 min may indicate a second mechanism of sedation, such as delayed rostral spread of local anesthetics. BIS was not a sensitive measure of the sedation associated with spinal anesthesia in the randomized, blinded portion of this study.     

Unexpected bronchospasm during spinal anesthesia

Asthma and bronchospastic disease are common in patients presenting for anesthesia. Intraoperative bronchospasm can be a life-threatening problem. One approach to these patients is to use regional anesthesia because it is believed that this will reduce the complication rate. Presented here is a case of bronchospasm occurring during regional anesthesia that was unresponsive to beta agonists. The use of atropine in the treatment of bronchospasm also is discussed.     

Bradycardia-tachycardia syndrome during spinal anesthesia

A 78-year-old man developed bradycardia with decreased level of consciousness followed by sinus arrest during femoropopliteal bypass surgery under subarachnoid anesthesia. Early in the recovery period, a similar clinical picture developed, with bradycardia but no change in level of consciousness. Sinus node automaticity or sinoatrial conduction abnormalities were suspected, and a 24-hour Holter electrocardiogram revealed bradycardia-tachycardia syndrome. The patient was prescribed amiodarone and anticoagulant therapy with acenocoumarol; no further episodes occurred during hospitalization. Bradycardia-tachycardia syndrome is a sinus node disorder that manifests intermittently. It can become apparent during or shortly after surgery, leading to problems of differential diagnosis.     

Severe lightning pain during spinal anesthesia

A 74-yr-old man was scheduled for the biopsy of prostatic tumor under spinal anesthesia. Preoperative serologic test for syphilis was highly positive. Spinal anesthesia was performed in the sitting position, and 2 ml of hyperbaric Neo-percamine S (a mixture of 0.24% dibucaine and 0.12% T-caine) was administered uneventfully with the onset of warm sensation on the perineal region. Ten minutes later, however, he began to complain of severe lightning sensation on the feet. After giving pentazocine intravenously, the short cystoscopic procedure was completed. As a cause of severe pain, an erroneous anesthetic solution or direct neuronal injury had been excluded because of rapid and complete recovery after anesthesia. Two weeks later, he was scheduled for TUR-P. He again complained of severe lightning pain after the successful spinal anesthesia with the same anesthetic solution. Because the pain was not relieved by analgesics, he was then anesthetized with enflurane and N2O in oxygen, and there were no neurological complications after anesthesia. Several cases of severe pain during spinal anesthesia have been reported in patients with tabes dorsalis. Although the patient lacks clear symptoms of neurosyphilis, positive serologic examination for syphilis without any other possible causes suggests altered sensitivity of the spinal cord to anesthetic solutions.     

Circulatory dynamics during surface-induced hypothermia under halothane-ether azeotrope anesthesia

Circulatory dynamics during surface- induced deep hypothermia using the halothane-diethyl ether azeotrope in 100% oxygen (O2) without circulatory arrest and 95% O2 and 5% carbon dioxide (CO2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO2 than in animals given 100% O2 during cooling. Cardiac output in the 5% CO2 groups increased until 30 degrees C cooling and then gradually decreased to 29% of control at 20 degrees C. Cardiac output in the 100% O2 group progressively decreased to 16% of control at 20 degrees C cooling and was 51 to 77% of the output in the 5% CO2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O2 and had only doubled in the 5% CO2 groups at 20 degrees C during cooling. Hemodynamic variables in animals given 5% CO2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane-diethyl ether azeotrope in 95% O2 and 5% CO2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.     

Asymptomatic spinal cord neoplasm detected during induction of spinal anesthesia

We report a case of an asymptomatic spinal cord neoplasm detected during the placement of a 25-gauge Whitacre spinal needle for spinal anesthesia before elective cesarean delivery. Subarachnoid blood was repeatedly aspirated during otherwise uncomplicated induction of spinal anesthesia. Magnetic resonance imaging revealed a spinal cord ependymoma in the lumbar spine. Asymptomatic spinal cord neoplasms and ependymomas are reviewed. Central nervous system pathology should be considered in the presence of persistent subarachnoid blood.     

Music decreases sedative requirements during spinal anesthesia

Ambulatory surgery can create significant anxiety. This prospective study measured whether music can influence anxiety and perioperative sedative requirements in outpatients undergoing surgery with spinal anesthesia. We also evaluated the correlation between two anxiety measures, the State-Trait Anxiety Inventory test (STAI) and the 0- to 10-cm visual analog scale (VAS 0-10), with 0 meaning complete relaxation and 10 the worst feeling of anxiety possible. Fifty unpremedicated patients were randomly assigned to listen to music of their choice via headset during the perioperative period (Group I) or to have no music (Group II). All participants used patient-controlled IV midazolam sedation and underwent repeated evaluations of their anxiety level with the STAI and the VAS 0-10. Midazolam requirements during surgery (Group I, 0.6 +/- 0.7 versus Group II, 1.3 +/- 1.1 mg; P < 0.05) and for the whole perioperative period (Group I, 1.2 +/- 1.3 versus Group II, 2.5 +/- 2.0 mg; P < 0.05) were smaller in patients listening to music. Anxiety levels, measured with STAI or VAS 0-10, were similar in both groups. The Spearman's coefficient values between STAI and VAS 0-10 ranged from 0.532 to 0.687. We conclude that patients listening to music require less midazolam to achieve a similar degree of relaxation as controls and that measures of anxiety obtained from the STAI and the VAS 0-10 are positively, but only moderately, correlated. IMPLICATIONS: It is possible to decrease sedative requirements during surgery under spinal anesthesia by allowing patients to listen to music to reduce their anxiety.     

Anaphylactoid reaction to dibucaine during spinal anesthesia

A 71-year-old man with a history of allergic rhinitis for 6 years received spinal anesthesia using 2 ml of 0.3% dibucaine for transurethral prostatectomy. Two months previously he had undergone prostate biopsy and cystoscopy under spinal anesthesia with isobaric bupivacaine uneventfully. Forty five minutes after injection of dibucaine he complained of itching in the periorbital area, and developed tremor and muscle rigidity followed by loss of consciousness. Soon after, his blood pressure decreased to 40 mmHg, and erythema appeared over his body. Symptoms were relieved by epinephrine, hydrocortisone and antihistamine agents, but ten minutes after the treatment he again developed hypotension and erythema. Continuous infusion of epinephrine was needed for complete relief of symptoms. An intradermal test with 0.3% dibucaine carried out 6 days after surgery demonstrated a 12 x 8 mm wheal with flare. Although anaphylactic reaction to an amide local anesthetic has been reported to be quite rare, this is the 7th case report of anaphylactic reaction to dibucaine used for spinal anesthesia in Japan.     

Hemiballism-hemichorea from marked hypotension during spinal anesthesia

Hemiballism and hemichorea following anesthesia-induced hypotension has rarely been described, but a recent case suggests an association. After experiencing marked hypotension during spinal anesthesia, a 70-year-old woman developed hemiballism and hemichorea. Involuntary ballistic movements with writhing, consisting of repetitive rotation and flexion-extension without apparent muscle weakness, affected her left limbs proximally. Low-amplitude, involuntary, choreiform movements involved the distal portions of these limbs. Magnetic resonance imaging demonstrated an area of high signal intensity in the contralateral subthalamic nucleus, suggestive of a focal ischemic lesion. Although such occurrences are rare, anesthesiologists should be aware of the risk of subthalamic nucleus ischemia following marked hypotension.