Harbhej Singh

Electroencephalogram bispectral analysis predicts the depth of midazolam-induced sedation.

BackgroundThe electroencephalogram (EEG) has been used to study the effects of anesthetic and analgesic drugs on central nervous system function. A prospective study was designed to evaluate the accuracy of various EEG parameters for assessing midazolam-induced sedation during regional anesthesia.Me

Intrathecal fentanyl prolongs sensory bupivacaine spinal block

The purpose of investigation was to study the effect of intrathecal fentanyl on the onset and duration of hyperbaric bupivacaine-induced spinal block in adult male patients. Fortythree patients undergoing lower extremity or genitourinary surgery were enrolled to receive either 13.5 mg hyperbaric bupivacaine 0.75% + 0.5 ml CSF it, (Group I) or 13.5 mg hyperbaric bupivacaine 0.75% + 25 μg fentanyl it, (Group II) according to a randomized assessor-blind protocol. The onset and duration of sensory block were assessed by pinching the skin with forceps in the midclavicular line bilaterally every two minutes for first twenty minutes and then every five to ten minutes. Similarly, the onset and duration of motor block were assessed and graded at the same time intervals using the criteria described by Bromage. The time required for two sensory segment regression and sensory regression to L1 dermatome was 74 ± 18 and 110 ± 33 min vs 93 ± 22 and 141 ± 37 min in Groups I and II, respectively (P < 0.05). Intrathecal fentanyl did not enhance the onset of sensory or motor block, or prolong the duration of bupivacaine-induced motor spinal block. Fewer patients demanded pain relief in the fentanyl-treated group than in the control group in the early postoperative period (19% vs 59%; P < 0.05). Episodes of hypotension were more frequent in the fentanyl-treated group than in the control group (43% vs 14%; P < 0.05). We conclude that fentanyl, 25 μg it, prolonged the duration of bupivacaine-induced sensory block (sensory regression to L1 dermatone) by 28% and reduced the analgesic requirement in the early postoperative period following bupivacaine spinal block.RésuméCette étude a pour objectif d’examiner l’effet du fentanyl sousarachnoïdien sur le début et la durée de la rachianesthésie hyperbare à la bupivacaïne chez des patients adultes de sexe masculin. Quarante-trois patients opérés sur une extrémité inférieure ou sur l’appareil génito-urinaire sont répartis pour recevoir au hasard en rachianesthésie soit 13,5 mg de bupivacaïne hyperbare à 0,75% avec 0,5 ml de LCR (groupe I), soit 13,5 mg de bupivacaïne hyperbare à 0,75% avec 25 μg de fentanyl (groupe II). Le debut et la durée du bloc sont évalués en coinćant la peau avec une pince sur la ligne médioclaviculaire bilatéralement à toutes les deux minutes pour les 20 premières minutes et à toutes les cinq à dix minutes par la suite. En même temps, le début et la durée du bloc moteur sont évalués et classé aux mêmes intervalles selon les critères de Bromage. Le temps requis pour la regression de deux segments sensoriels et la régression sensorielle jusqu’au dermatome de L1 est de 74 ± 18 et 110 ± 33 vs 93 ± 22 et 141 ± 37 min dans les groupes I et II respectivement (P < 0,05). Le fentanyl sousarachnoïdien n’accélère pas le début des blocs sensoriel et moteur ni ne prolonge la durée du bloc moteur produit par la bupivacaïne. Moins de patients ont demandé un analgésique dans le groupe fentanyl que dans le groupe contrôle à la période postopératoire immédiate (19% vs 59% P < 0,05). Les épisodes d’hypotension sont plus fréquents dans le groupe traité au fentanyl que dans le groupe contrôle (43% vs 14%, P < 0,05). Les auteurs concluent que le fentanyl 25 μg sous-arachoïdien prolonge la durée du bloc senstif induit par la bupivacaïne (mesurée par la régression au dermatome de L1) par 28% et diminue les besoins en analgésie dans le période postopératoire immédiate après une rachianesthésie.

Effects of ketorolac versus bupivacaine coadministration during patient-controlled hydromorphone epidural analgesia after thoracotomy procedures

We studied the comparative effects of ketorolac versus bupivacaine supplementation of hydromorphone (HM) patient-controlled epidural analgesia (PCEA) on the HM requirement, postoperative pain, and pulmonary function in 62 consenting patients after thoracotomy procedures. Patients were randomly assigned to receive one of three different combinations of analgesic medications after the operation according to a double-blind, placebo-controlled study. The treatment groups consisted of: Group 1 (n = 23): PCEA HM 3-mL (0.15 mg) bolus doses + saline 1 mL intravenously (IV) q6h, Group 2 (n = 20): PCEA HM (0.15 mg) in 0.125% bupivacaine 3-mL bolus doses + saline 1 mL IV q6h, and Group 3 (n = 19): PCEA HM 3-mL (0.15 mg) bolus doses + ketorolac 1 mL (30 mg) IV q6h. Epidural HM and supplemental analgesic requirements, pain visual analog scale (VAS) scores, the incidence of nonincisional pain, and side effects were recorded at 24 and 48 h after surgery. Bedside pulmonary function tests were performed using a Puritan Bennett 100[TM] (Puritan-Bennett Corp., Wilmington, MA) spirometer before and 24 and 48 h after surgery. IV ketorolac supplementation of HM PCEA significantly reduced the incidence of nonincisional pain and the HM requirement over 48 h compared with the HM PCEA alone group (7% vs 26%; 3 +/- 1.6 mg vs 5.3 +/- 2.8 mg). Both ketorolac and bupivacaine supplementation of HM PCEA reduced the severity of pain on coughing and on movement compared with HM PCEA alone on postoperative day (POD) 1. Significant reductions in forced vital capacity, forced expiratory volume in 1 s, forced expiratory flow 25%-75% of the vital capacity, and peak expiratory flow rate (PEFR) were noted on PODs 1 and 2 in all three treatment groups. The decrease in PEFR on PODs 1 and 2 was significantly less with ketorolac compared with bupivacaine supplementation. We conclude that ketorolac supplementation of HM PCEA reduces the incidence of nonincisional pain and HM requirement compared with HM PCEA alone and may have a beneficial effect on pulmonary function compared with bupivacaine supplementation of HM PCEA in postthoracotomy patients. (Anesth Analg 1997;84:564-9)

Relationship between diabetic autonomic neuropathy and gastric contents.

Delayed gastric emptying secondary to diabetic autonomic neuropathy (DAN) is a recognized risk factor for aspiration pneumonitis. The purpose of this study is to determine whether bedside autonomic function tests (AFTs) would predict gastric contents. Gastric volume and its pH were measured in 36 patients with diabetes mellitus (DM) and 15 nondiabetic patients at induction of general anesthesia for elective ambulatory surgery. Manifestations of autonomic dysfunction were assessed preoperatively in all 51 patients with five commonly used cardiovascular AFTs. According to the results of these five tests, 16 patients with DM met the criteria for the diagnosis and are called “DAN positive.” The remaining 20 diabetics did not meet the criteria and are called “DAN negative.” Fifteen patients without DM did not meet the criteria and are called “nondiabetics.” Diabetic patients were significantly older and more obese than nondiabetics and those with DM more than 10 yr were more often DAN positive. Solid, undigested food particles were found more often in the gastric contents of DAN-positive patients compared to nondiabetics. Gastric liquid volume and pH were similar in diabetic patients (DAN positive and DAN negative) and nondiabetic controls. These results demonstrate that diagnosis of DAN by commonly used cardiovascular AFTs does not predict larger gastric liquid volume or lower pH, but does predict the presence of solid food particles. The presence of food particles in gastric contents after 8 h of fasting could represent a risk factor for aspiration pneumonitis. Autonomic neuropathy is not manifested equally in the cardiovascular and gastrointestinal systems, but may be more severe in one than the other.

Effect of oral clonidine and intrathecal fentanyl on tetracaine spinal block

We studied the effect of oral clonidine and intrathecal (IT) fentanyl on the onset and duration of a hyperbaric tetracaine-induced spinal block. Forty adult males undergoing elective surgery were studied according to a randomized, double-blind, placebo-controlled protocol involving four treatment regimens: Group I, placebo per os (PO) + tetracaine 12 mg IT; Group II, placebo PO+tetracaine 12 mg IT+fentanyl 10 micrograms IT; Group III, clonidine 200 micrograms PO+tetracaine 12 mg IT; Group IV, clonidine 200 micrograms PO+tetracaine 12 mg IT+fentanyl 10 micrograms IT. Onset time to highest sensory level was 8.5 +/- 3.1, 8.2 +/- 2.3, 6.1 +/- 1.6, and 6.8 +/- 1.4 min in Groups I, II, III, and IV, respectively. The time required for sensory regression to the L1 dermatome level was 153 +/- 34, 151 +/- 51, 183 +/- 63, and 209 +/- 39 min in Groups I, II, III, and IV, respectively. Similarly, the duration of Grade III motor block was 132 +/- 37, 140 +/- 55, 160 +/- 51, and 189 +/- 52 min in Groups I, II, III, and IV, respectively. IT fentanyl 10 micrograms did not change the onset or duration of tetracaine-induced spinal block. Furthermore, there was no significant interaction between clonidine and fentanyl in Group IV. Episodes of bradycardia and hypotension were more frequent in the clonidine-treated patients (40%-50% vs 10%). We conclude that oral clonidine (200 micrograms) shortened the onset time of tetracaines sensory block and prolonged the duration of sensory and motor block. However, clonidine premedication increased the risk of hypotension and bradycardia.

Perioperative anaesthetic considerations for patients undergoing lung transplantation

PurposeFive thousand. two hundred and eight lung transplants were performed worldwide before April, 1996. This review will discuss lung transplantation from an historical perspective, its indications, donor and recipient selection criteria, donor lung preparation, surgical considerations, perioperative anaesthetic management, and associated morbidity and mortality.SourceRecent literature on penoperative anaesthetic management of lung transplantation and experience from international centres including the Toronto Lung Transplant Group and the St. Louis Lung Transplant Group.Principal findingsLung transplantation comprises of a family of operations, including single lung transplant, bilateral single lung transplant, lobar transplant and block heart-lung transplant Improved donor lung preservation techniques have increased the duration of cold ischaemic time. The advent of bilateral single lung transplant has decreased the requirement for cardiopulmonary bypass, and airway complications have been reduced by adoption of the telescoping bronchial anastomoses. Advances in perioperative monitoring (including transoesophgeal echocardiography). pulmonary vasodilators (e.g., nitric oxide and prostaglandin E1), cardiopulmonary bypass and ventilatory management, and a better understanding of the pathophysiological processes during the procedure have improved penoperative anaesthetic management. Also, advances in broad spectrum antibiotics and immunosuppressant drugs have improved the outcome by better management of the complications of infection and rejection.ConclusionLung transplantation improves the quality of life with marginal improvement in life expectancy of the recipients. It is an expensive procedure requinng continued resources for long term management of these patients.RésuméObjectifJusqu’en avnl 1996, cinq mille, deux cent huit transplantations de poumons avaient déjà été effectuées à travers le monde. Ce survol permettra de discuter de la transplantation pulmonaire dans sa perspective historique, ses indications, les critères de sélection du receveur et du donneur, la préparation du poumon du donneur, les considérations chirurgicales, la gestion pénopératoire de l’anesthésie et la mortalité et la morbidité associées.SourceLes publications récentes traitant de la gestion périopératoire de la transplantation pulmonaire et de l’expérience acquise par des centres internationaux dont le TorontoLung Transplant Group et leSt.Louis Lung Transplant Group.Principales constatationsLa transplantation pulmonaire englobe une famille d’interventions dont la transplantation unipulmonaire. bilatérale simple, lobaire et coeur-poumons en bloc. Lamélioration des techniques de préservation des poumons du donneur a permis l’amélioration de la durée de l’ischémie froide. L’avènement de la transplantation bilatérale simple a réduit la nécessité de la circulation extracorporelle et l’introduction des anastomoses télescopiques a permis de réduire les complications particulières aux voies aériennes. Le perfectionnement du monitorage pénopératoire (dont l’échographie transoesophagienne), des vasodilatateurs pulmonaires (par ex., l’oxyde nitrique et la prostaglandine El), de la gestion de la circulation extracorporelle et de la ventilation, et une meilleure connaissance du processus physiopathologique propre à l’intervention ont permis d’améliorer la conduite anesthésique périopératoire. Également, les progrès réalisés dans l’antibiothérapie à large spectre autorisent un pronostic plus favorable grâce à un meilleur contrôle de l’infection et du rejet.ConclusionLa transplantation pulmonaire améliore considérablement la qualité de vie mais marginalement l’expectative vitale. Elle coûte cher et requiert des ressources continues pour la prise en charge à long terme des transplantés.

Optimal Dose of Nicardipine for Maintenance of Hemodynamic Stability After Tracheal Intubation and Skin Incision

To determine the optimal dose of nicardipine (N) for maintenance of hemodynamic stability during the postinduction period, we designed a randomized, double-blind, placebo-controlled, dose-ranging study using four different doses of N administered after a standardized anesthetic induction sequence. A total of 106 patients were assigned to one of the following treatment groups: saline (control), N0.5 mg (N0.5), N1 mg (N1), N2 mg (N2), and N4 mg (N4). The study medication was administered intravenously (IV) in 2.5 mL of saline over 30 s 2 min before laryngoscopy. Mean arterial pressure (MAP) and heart rate (HR) were recorded at 1-min intervals for 15 min after tracheal intubation and for 5 min after skin incision. After intubation, the peak MAP values differed from the preinduction baseline MAP values by 21% +/- 20%, 9% +/- 12%, 1% +/- 13%, -10% +/- 12%, and -15% +/- 13% (mean +/- SD) in the control, N0.5, N1, N2, and N4 groups, respectively. However, the percent change in the pre- to postintubation MAP values (37% to 47%) was similar in all five groups. The highest postintubation HR values were recorded in the N4 group (P < 0.05 versus the other groups). However, the increases in MAP values after skin incision were the least in the N4 group. In conclusion, N1 IV, administered 2 min before laryngoscopy provides optimal control of arterial blood pressure during the postinduction period. Implications: Acute increases in blood pressure during anesthesia are undesirable in patients with preexisting cardiovascular diseases. This double-blind study found that the calcium-channel blocker, nicardipine, 1 mg intravenously 2 min before tracheal intubation maintained hemodynamic stability during the intraoperative period. (Anesth Analg 1997;85:1247-51)