Anis Baraka

Effect of low‐dose dexmedetomidine or clonidine on the characteristics of bupivacaine spinal block

Background:  The purpose of this study was to compare the onset and duration of sensory and motor block, as well as the hemodynamic changes and level of sedation, following intrathecal bupivacaine supplemented with either dexmedetomidine or clonidine.

Preoxygenation: Comparison of Maximal Breathing and Tidal Volume Breathing Techniques

BACKGROUND Preoxygenation with tidal volume breathing for 3-5 min is recommended by Hamilton and Eastwood. This report compares tidal volume preoxygenation technique with deep breathing techniques for 30-60 s. METHODS The study was conducted in two parts on patients undergoing elective coronary bypass grafting. In the first group (n = 32), each patient underwent all of the following preoxygenation techniques: the traditional technique consisting of 3 min of tidal volume breathing at an oxygen flow of 5 l/min; four deep breaths within 30 s at oxygen flows of 5 l/min, 10 l/min, and 20 l/min; and eight deep breaths within 60 s at an oxygen flow of 10 l/min. The mean arterial oxygen tensions after each technique were measured and compared. In the second group (n = 24), patients underwent one of the following techniques of preoxygenation: the traditional technique (n = 8), four deep breaths (n = 8), and eight deep breaths (n = 8). Apnea was then induced, and the mean times of hemoglobin desaturation from 100 to 99, 98, 97, 96, and 95% were determined. RESULTS In the first group of patients, the mean arterial oxygen tension following the tidal breathing technique was 392+/-72 mm Hg. This was significantly higher (P<0.05) than the values obtained following the four deep breath technique at oxygen flows of 5 l/min (256+/-73 mm Hg), 10 l/min (286+/-69 mm Hg), and 20 l/min (316+/-67 mm Hg). In contrast, the technique of eight deep breaths resulted in a mean arterial oxygen tension of 369+/-69 mm Hg, which was not significantly different from the value achieved by the traditional technique. In the second group of patients, apnea following different techniques of preoxygenation was associated with a slower hemoglobin desaturation in the eight-deep-breaths technique as compared with both the traditional and the four-deep-breaths techniques. CONCLUSION Rapid preoxygenation with the eight deep breaths within 60 s can be used as an alternative to the traditional 3-min technique.

Intrathecal Injection of Morphine for Obstetric Analgesia

Intrathecal injection of morphine was used to provide obstetric analgesia in 20 primiparous women in labor. When the cervix was at least 3 cm dilated, morphine, 1 or 2 mg, was injected intrathecally. In all parturients, labor pains were completely relieved after 15–60 min and analgesia lasted as lon

Anaesthesia and myasthenia gravis

Myasthenia gravis is an autoimmune disease, resulting from the production of antibodies against the acetylcholine receptors of the endplate. These antibodies reduce the number of active receptors, brought about either by functional block of the receptors, by increased rate of receptor degradation, or by complement-mediated lysis. In myasthenic muscles, the miniature endplate potential amplitude is decreased, and a large proportion of the endplate potentials are subthreshold. Repetitive nerve stimulation results in a decremental response. The disease is frequently associated with morphological abnormalities of the thymus. In young patients, thymic hyperplasia is common while thymoma is more frequent in elderly patients. Medical treatment of myasthenia gravis aims at improving of neuromuscular transmission by anticholinesterases, suppressing the immune system by corticosteroids and immunosuppressents, or by decreasing the circulating antibodies by plasmapheresis. Adults with generalized myasthenia should have a transsternal thymectomy. A balanced technique of general anaesthesia which includes the use of muscle relaxants can be safely used, provided neuromuscular transmission is monitored. Myasthenic patients are sensitive to nondepolarizing relaxants but intermediate-acting nondepolarizing relaxants such as atracurium and vecuronium are eliminated rapidly, and can be titrated to achieve the required neuro-muscular block that can be completely reversed at the end of surgery. Postoperatively, ventilatory support may be required in high-risk patients. Also, medical treatment may be maintained, tapered or discontinued depending on the outcome of surgery. Thymectomy benefits nearly 96% of patients, 46% develop complete remission and 50% are asymptomatic or improve on therapy.RésuméLa myasthénie grave est une maladie auto-immune résultant de la production d’anticorps contre les recepteurs d’acétylcholine sur la plaque motrice. Ces anticorps réduisent le nombre de récepteurs actifs, soit par un bloc fonctionnel des récepteurs, par une augmentation de la vitesse de dégradation du récepteur ou par une lyse provoquée par les complements. Avec les muscles myasthéniques, l’amplitude du potentiel miniature de la plaque motrice est diminuée et une grande proportion des potentiels est sous le seuil d’excitation. Une stimulation nerveuse répétitive produit une réponse qui diminue graduellement. La maladie est associée fréquemment à des anomalies morphologiques du thymus. L’hyperplasie du thymus est commune chez les jeunes patients, alors que le thymome est plus fréquent chez les patients plus âgés. Le traitement médical de la myasthénie grave vise l’amélioration de la transmission neuromusculaire à l’aide d’anticholinestérasiques, la suppression du système immunitaire à l’aide de corticostéroïdes et d’immunosuppresseurs, ou la diminution des anticorps circulant à l’aide de la plasmaphérèse. Les adultes qui présentent une myasthénie généralisée devraient subir une thymectomie trans-sternale. Une technique balancée d’anesthésie générale peut être utilisée avec sécurité, incluant l’utilisation des myorésolutifs, en autant que la transmission neuromusculaire est monitorée. Les patients myasthéniques sont sensibles aux myorésolutifs non-dépolarisants, mais les rélaxants à action intermédiate tel que l’atracurium et le vécuronium sont éliminés rapidement et peuvent être dosés pour obtenir un bloc neuromusculaire adéquat et complètement réversible à la fin de la chirurgie. Un support ventilatoire peut être requis dans la periode post-operatoire chez les patients à haut risque. Le traitement médical peut être maintenu, diminué ou cessé selon l’issue de la chirurgie. Pres de 96% des patients bénéficient de la thymectomie, 46% développent une rémission complète et 50% sont asymptomatiques ou s’améliorent avec le traitement.

A comparison of epidural tramadol and epidural morphine for postoperative analgesia

The present study compared epidural tramadol with epidural morphine for postoperative analgesia in 20 patients undergoing major abdominal surgery. Intraoperatively, the patients were anaesthetized by a balanced technique of general anaesthesia combined with lumbar epidural lidocaine. In ten of the patients 100 mg tramadol diluted in 10 ml normal saline was also injected epidurally, while 4 mg epidural morphine was used in the other ten patients. In all patients, the visual analogue pain score, PaO2, PaCO2 and respiratory rate were monitored every hour for the first 24 hr postoperatively. In both the tramadol and morphine groups, the mean hourly pain scores ranged from 0.2 ± 0.6 to 1.4 ± 2.5 throughout the period of observations. However, the mean PaO2 was decreased postoperatively in the epidural morphine group, while no change was observed in the epidural tramadol group. The maximal decrease of PaO2 in the epidural morphine group was observed at the tenth hour postoperatively, when it decreased to 72.8 ± 10.3 mm Hg. This was not associated with any increase in PaCO2 or a decrease of respiratory rate, suggesting that hypoxaemia rather than hypercarbia or decreased respiratory rate may be an earlier indicator of respiratory depression in patients breathing room air without oxygen supplementation. The absence of clinically relevant respiratory depression following epidural tramadol compared with epidural morphine may be attributed to the different mechanisms of their analgesic action. The results suggest that epidural tramadol can be used to provide prolonged postoperative analgesia without serious side effects.RésuméCette étude compare le tramadol à la morphine donnée par voie épidurale pour l’analgésie postopératoire de 20 patients subissant une chirurgie abdominale majeure. Les patients sont anesthésiés par une technique balancée, combinée à une épidurale lombaire à la lidocaïne. Chez dix des patients, tramadol 100 mg dilué de 10 ml de liquide physiologique est également injecté par voie épidurale, tandis que morphine épidurale 4 mg est injectée aux autres patients. Chez tous les patients, une échelle visuelle analogue de la douleur, la PaO2, la PaCO2 et la fréquence respiratoire sont mesurées chaque heure pendant les 24 premières heures postopératoires. Autant dans le groupe tramadol que dans le groupe morphine, la valeur moyenne de l’évaluation de la douleur se situé de 0,2 ± 0,6 à 1,4 ± 2,5 pendant toute la période d’observation. La PaO2 moyenne est cependant diminuée en postopératoire dans le groupe épidurale à la morphine tandis qu’aucun changement n’est observé dans le groupe épidurale au tramadol. La diminution maximum de la PaO2 dans le groupe épidurale à la morphine se situe à la dixième heure postopératoire, et atteint une valeur de 72,8 ± 10,3 mm Hg. Elle n’est associée à aucune augmentation de PaCO2 ni à une diminution de fréquence respiratoire, suggérant que l’hypoxémie plutôt que l’hypercapnie vu la diminution de fréquence respiratoire peut être un indice précoce de la dépression respiratoire chez des patients respirant l’air ambiant sans supplément d’oxygène. L’absence de dépression respiratoire cliniquement significative après une épidurale au tramadol par rapport à une épidurale à la morphine peut être attribuée à un mécanisme d’action analgésique différent. Ces résultats suggèrent qu’une épidurale au tramadol peut être utilisée pour procurer une analgésie post-opératoire prolongée sans effets secondaires sérieux.

Diclofenac and/or propacetamol for postoperative pain management after cesarean delivery in patients receiving patient controlled analgesia morphine.

Background and Objectives A multimodal approach to postcesarean pain management may enhance analgesia and reduce side effects after surgery. This study evaluates the postoperative analgesic effects of propacetamol and/or diclofenac in parturients undergoing elective cesarean delivery under spinal anesthesia. Methods After randomization, 80 healthy parturients received the following: placebo (group M), 100 mg diclofenac rectally every 8 hours (group MD), 2 g propacetamol intravenously every 6 hours (group MP), or a combination of 2 g propacetamol and 100 mg diclofenac (group MDP) as described above. Drugs were administered for 24 hours after surgery. Postoperative pain was controlled with a patient controlled analgesia pump, using morphine. The visual analog scale (VAS) at rest and on coughing, as well as the morphine consumption, were evaluated at 2, 6, and 24 hours postoperatively. Also, the side effects experienced after undergoing the different regimens were compared. Results The patients’ characteristics did not differ significantly between the 4 groups. VAS score at 2 hours, both at rest and on coughing were lower in group MDP and MD compared with group M (P < .05). At 24 hours, there was still a tendency toward lower pain scores in the groups MDP and MD; however, this difference was only statistically significant at rest between the MDP group and the MP and M groups. Morphine consumption at 2, 6, and 24 hours was lower in the MDP and MD groups compared with the MP and M groups (P < .05). The morphine-sparing effect was higher in groups MDP and MD compared with group MP (57% and 46%, respectively, v 8.2%, P < .05). The incidence of side effects was similar in all groups. However, the power of the study was too low to permit an evaluation of potential side effects. Conclusion Diclofenac after cesarean delivery improves analgesia and has a highly significant morphine-sparing effect. We were unable to demonstrate significant morphine-sparing effect of propacetamol or additive effect of propacetamol and diclofenac in this group of patients.

The effect of dexamethasone on postoperative vomiting after tonsillectomy.

UNLABELLED In this double-blinded, randomized, placebo-controlled study, we assessed the effect of dexamethasone 0.5 mg/kg IV administered preoperatively in 110 children 2-12 yr old, undergoing electrodissection adenotonsillectomy, using a standardized anesthetic technique. The incidence of early and late vomiting, the time to first oral intake, the quality of oral intake, the satisfaction scores, and the duration of IV hydration were compared in both groups. The overall incidence of vomiting, as well as the incidence of late vomiting, was significantly less in the Dexamethasone group as compared with the Saline group (23% and 19% vs 51% and 34%, respectively). The time to first oral intake and the duration of IV hydration were shorter in the Dexamethasone group compared with the Saline group (P < 0.05). The quality of oral intake and the satisfaction scores were better in the Dexamethasone group than in the Saline group (P < 0.05). This report confirms the beneficial effect of IV dexamethasone on both vomiting and oral intake in children undergoing electrodissection adenotonsillectomy. IMPLICATIONS In this double-blinded, placebo-controlled study, we examined the efficacy of a single dose of dexamethasone 0.5 mg/kg IV on posttonsillectomy vomiting and oral intake in children 2-12 yr old. Dexamethasone significantly decreased the incidence of postoperative vomiting during the first 24 h, shortened the time to the first oral intake and the duration of IV hydration, and improved the quality of oral intake and the satisfaction scores of the patients.

Nasopharyngeal oxygen insufflation following pre-oxygenation using the four deep breath technique

This paper evaluates the effectiveness of nasopharyngeal oxygen insufflation following preoxygenation using the four deep breath technique within 30 s, on the onset of haemoglobin desaturation during the subsequent apnoea. Thirty ASA I or II patients were randomly allocated to one of two groups. In the study group (n = 15), pre‐oxygenation was followed by insufflation of oxygen at a flow of 5 l.min−1 via a nasopharyngeal catheter commenced at the onset of apnoea. In the control group, pre‐oxygenation was not followed by nasopharyngeal oxygen insufflation (n = 15). In the control group, Spo2 fell to 95% within a mean (SD) apnoea time of 3.65 (1.15) min, whereas in the study group, Spo2 was maintained in all patients at 100% throughout the 6 min of apnoea, at which point apnoea was terminated and positive pressure ventilation commenced. We conclude that nasopharyngeal oxygen insufflation following pre‐oxygenation using the four deep breath technique can delay the onset of haemoglobin desaturation for a significant period of time during the subsequent apnoea.

Preoxygenation of pregnant and nonpregnant women in the head-up versus supine position

The influence of preoxygenation in the supine (n = 10) versus the 45 degrees head-up (n = 10) position on the duration of apnea leading to a decrease in arterial oxygen saturation to 95%, as monitored by pulse oximetry, was investigated in 20 women undergoing elective cesarean section at term of pregnancy. The results were compared with those obtained in a control group of 20 nonpregnant women. In the supine position, the average time to desaturation to 95% was significantly shorter in the pregnant group (173 +/- 4.8 s [mean +/- SD]) than in the control group of nonpregnant women (243 +/- 7.4 s). Using the head-up position resulted in an increase in the desaturation time in the nonpregnant group (331 +/- 7.2 s) but had no significant effect in the pregnant group (156 +/- 2.8 s). We conclude that pregnant women desaturate their arterial blood of oxygen more rapidly than do nonpregnant women. Furthermore, the head-up position extends the duration of apnea that can take place before desaturation occurs in nonpregnant patients.

Preoperative caudal block prevents emergence agitation in children following sevoflurane anesthesia

Background:  The frequency of emergence agitation in children is increased following sevoflurane anesthesia. However, controversies still exist concerning the exact etiology of this postanesthetic problem. Although this phenomenon is present with adequate pain relief or even following pain‐free procedures, pain is still regarded as a major contributing factor.