Bill Y. Ong

Gastric volume and pH in out-patients.

SummaryWe measured the volume and pH of the gastric content of 21 out-patients and 21 in-patients under general anaesthesia. Gastric tubes were inserted after induction of anaesthesia, and gastric fluids were withdrawn for pH determinations. Gastric volumes were measured by a dilution technique using polyethylene glycol as the indicator and also by measurement of the volume aspirated through agastric tube. Out-patients had a mean gastric volume of 69 ± 17 ml while inpatients had a mean volume of 33 ± 4 ml. The average gastric pH for the out-patients was 1.8 ± 0.2 and for the in-patients 2.0 ± 0.3. Four outpatients had more than 75 ml of gastric fluid of pH less than 2.0. Aspiration through a gastric tube did not empty the stomach completely and the volume thus obtained gave a falsely low estimate of the gastric volume.RésuméNous avons déterminé le pH et le volume du liquide gastrique chez 21 malades hospitalisés, opérés sous anesthésie générale, et chez 21 autres patients ambulatoires, soumis à une anesthésie générale pour chirurgie. A cet effet, nous avons mis en place une sonde nasogastrique avant ľinduction de ľanesthésie et avons prélevé du liquide gastrique pour en déterminer le pH. Nous avons également fait la mesure du volume liquidien gastrique au moyen ďune technique de dilution, le polyéthylène glycol servant ďindicateur, ainsi que par la mesure directe du volume total que nous pouvions aspirer.Les malades ambulatoires avaient un volume moyen de 69 ± 17 ml, alors que les patients hospitalisés avaient un volume de 33 ± 4 ml. Le pH du liquide gastrique des malades non hospitalisés était de 1.8 ± 0.2, alors qu’il était de 2.0 ± 0.3 chez les malades hospitalisés. Quatre des patients ambulatoires avaient plus de 75 ml de liquide dans ľestomac et à un pH de moins de 2.0. La succion appliquée à la sonde naso-gastrique ne permettait pas de vider complètement ľestomac et les volumes ainsi obtenus donnaient des résultats inférieurs à la réalité.

Paresthesias and motor dysfunction after labor and delivery

The incidence of paresthesias and motor dysfunction associated with 23,827 deliveries at Winnipeg Womens Hospital during a 9-yr period (1975–1983) was 18.9/10,000 deliveries. All the symptoms resolved within 72 hr after supportive therapy only. The frequency of paresthesias and motor dysfunction was greater in primiparas, women who had forceps- or vacuum-assisted deliveries, and women who had epidural or general anesthesia. Significant neurologic deficits after labor and delivery with or without epidural anesthesia were rare. Epidural anesthesia is a safe technique in this regard.

Continuous epidural ropivacaine 0.2% for analgesia after lower abdominal surgery

The purpose of this study was to determine whether a lumbar epidural infusion of ropivacaine 0.2% would provide effective analgesia with an acceptably low incidence of motor blockade and side effects after lower abdominal surgery. After combined general and epidural anesthesia and surgery, 125 patients were randomly assigned to receive either saline or ropivacaine 0.2% at a rate of 6, 8, 10, 12, or 14 mL/h (Groups R6, R8, R10, R12, and R14, respectively) for 21 h. Supplemental analgesia, if required, was provided with intravenous patient-controlled analgesia with morphine. Data were collected at 4, 8, and 21 h, and included morphine consumption, pain scores at rest and with coughing, motor and sensory block, and adverse events. Cumulative morphine consumption was less in Groups R10, R12, and R14 compared with the saline group. At 4 h analgesia was better among patients receiving ropivacaine, but at 21 h pain scores were identical. Sensory blockade at 8 and 21 h was greater in the ropivacaine groups compared with the saline group. Approximately 30% of R8, R10, and R12 patients, and 63% of R14 patients had demonstrable motor block of the lower limbs at 21 hours. We conclude that lumbar epidural ropivacaine 0.2% reduces parenteral morphine requirements but has little effect on pain scores and may be associated with motor blockade. (Anesth Analg 1997;84:784-90)

Anesthesia for cesarean section: effects on neonates

The effects of general and regional anesthesia on neonates after cesarean section have been studied mainly on elective cases. In this paper we studied infants delivered by elective and nonelective cesarean section at the Winnipeg Womens Hospital from 1975 to 1983 (n = 3940) to determine the effect of anesthetic technique on neonatal outcomes. A trained anesthesia nurse interviewed all parturients and reviewed their antepartum, labor and delivery, and anesthesia records. Assessments of neonatal outcomes were based on 1− and 5-minute Apgar scores, need for positive pressure oxygen by mask or intubation, and neonatal deaths (within 30 days). These outcomes were determined in three subgroups of neonates delivered by cesarean section: those delivered by elective section, those delivered by urgent cesarean section for dystocia or failure of labor to progress, and those delivered by section because of fetal distress. Overall, 12.5% of the infants had 1-minute Apgar scores of 4 or less, and 1.4% had 5-minute Apgar scores of 4 or less. Neonates born to mothers given general anesthesia had worse outcomes than those born to mothers given regional anesthesia. Among neonates delivered after elective section, general anesthesia was associated with a higher incidence of low Apgar scores at 1 minute. In neonates delivered by nonelective section, general anesthesia was associated with higher rates of low Apgar scores at 1 and 5 minutes as well as greater requirements for intubation and artificial ventilation. There were no differences seen in neonatal death rates with general and regional anesthesia in the three groups. Using a multivariate analysis to control for differences among neonates with regard to maternal age, parity, presence of antepartum disease, labor complications, presence of fetal distress, gestational age, multiple birth, use of narcotics or sedatives during labor, elective versus nonelective section, and year of birth, the risk of poor neonatal outcome remained greater after general anesthesia than after regional anesthesia. We conclude that infants delivered by cesarean section under general anesthesia are more likely to be depressed and more likely to require active resuscitation than those delivered by cesarean section with regional anesthesia. However, with appropriate neonatal care, the choice of anesthetic technique does not appear to affect neonatal survival in the short term.

Prolonged Epidural Infusions of Ropivacaine (2 mg/ml) After Colonic Surgery: The Impact of Adding Fentanyl

We evaluated the safety and efficacy of a 72-h epidural infusion of ropivacaine and measured the impact of adding fentanyl 2 &mgr;g/mL to the required infusion rate, on the quality of postoperative pain relief and the incidence of side effects, after colonic surgery. One hundred fifty-five patients scheduled for elective colonic surgery were randomized in this trial. Epidural infusions of ropivacaine 2 mg/mL with fentanyl 2 &mgr;g/mL (R + F) and without fentanyl (R) were commenced during surgery and continued for 72 h postoperatively. This was a prospective, randomized, double-blinded, multi-center trial. The median infusion rate required was less in the R + F group (9.3 vs 11.5 mL/h, P < 0.001). Median pain scores at rest and on coughing were lower in the R + F group (P < 0.0001). The incidence of hypotension was more in the R + F group (P = 0.01). Time to readiness for discharge was delayed in the R + F group (median 6.6 vs 5.5 days, P = 0.012). The addition of fentanyl to ropivacaine resulted in decreased infusion rates and enhanced pain control; however, adverse effects were increased and readiness to discharge was delayed.

Subarachnoid bupivacaine decreases spinal cord blood flow in dogs

Eigtheen mongrel dogs were randomized into two equal groups. Cervical, thoracic and lumbosacral spinal cord and spinal dural blood flows were measured using the radioactive microsphere technique. Blood flow determinations were made prior to, and 20 and 40 minutes following lumbar subarachnoid injection of: (1) 0.4 per cent bupivacaine (20 mg), or (2)0.4 per cent bupivacaine (20 mg) with 1/25,000 epinephrine (200 μg).In dogs given subarachnoid bupivacaine or bupivacaine with epinephrine, the maximum decrease in mean arterial blood pressure (33 per cent) occurred at 40 minutes post-injection. Cardiac index decreased in dogs given subarachnoid bupivacaine (197 ± 11 ml·kg-1·min-1 controlvs. 141 ± 19 ml·kg-1 min-1 at 40 minutes), while it increased in dogs given bupivacaine with epinephrine (201 ± 11ml·kg-1·min-1 - control vs. 252 ± 15 ml · kg-1 · min-1 at 40 minutes). Dogs receiving subarachnoid bupivacaine demonstrated a significant decrease in spinal cord blood flow to all regions. Dogs receiving subarachnoid bupivacaine with epinephrine demonstrated a significant decrease in thoracic and lumbosacral spinal cord blood flow; however, cervical cord blood flow remained unchanged. Thoracic and lumbosacral dural blood flows were significantly decreased in both groups following subarachnoid injection.Subarachnoid bupivacaine 0.4 per cent (20 mg) and 0.4 per cent with epinephrine 1/25,000 (200 μg) decrease spinal cord and spinal dural blood flow in dogs.RésuméDix-huit chiens bâtards ont été randomisés en deux groupes égaux. Les débits sanguins de la moelle épinière et de la duremère dans les régions cervicale, thoracique et lombo-sacrée ont été mesurés en utilisant la technique des microspherès radioactives. Les déterminations des flots snaguins ont été faites avant, 20 et 40 minutes après l’injection sous-arachnoïdienne lombaire de: 1) 0.4 pour cent bupivacaïne (20 mg) ou, 2) 0.4 pour cent bupivacaine (20 mg) avec 1/25,000 épinéphrine (200 μg @#@). Les chiens ayant requ l’injection de bupivacaïne sous-arachnoïdienne ont démontré une diminution significative dans le flot sanguin de la moelle épinière dans toutes les régions. Les chiens ayant reçu la bupivacaïne intrathecale avec épinéphrine ont démontré une diminution significative du flot sanguin dans les régions thoracique et lombo-sacrée; cependant, le flot sanguin de la moelle épinière dans la région cervicale est demeure inchangé. Les flots sanguins de la duremère dans les régions thoracique et lombo-sacrée ont été diminués significativement dans les deux groupes après injection sous-arachnoïdienne.L’injection sous-arachnoïdienne de bupivacaïne 0.4 pour cent (20 mg) et 0.4 pour cent avec épinéphrine 1/25,000 (200 μg @#@) diminue le flot sanguin dans la moelle epiniere ainsi que dans la duremére chez les chiens.

Fetal Anesthetic Requirement (MAC) for Halothane

: We asked whether the anesthetic requirement (MAC) of fetal lambs is lower than that of pregnant ewes. In five pregnant ewes anesthetized with a subarachnoid block, a fetal foot was withdrawn through a hysterotomy. The ewe then breathed 1.5% halothane and a clamp was applied to the fetal foot at 2-min intervals. We concomitantly obtained arterial blood from previously implanted catheters. When fetal movement in response to clamping the foot ceased, halothane was discontinued and the stimulus and sampling continued until the fetus began to move. Anesthesia was again resumed and continued until movement stopped. Anesthesia was then deepened and MAC was determined in the mother (stimulus--ear clamp). The fetal blood concentrations of halothane at MAC were 48 +/- 28 mg/L; they were 133 +/- 5 mg/L in the mother. This difference was highly significant (P less than 0.001). Calculated end-tidal concentrations were 0.33% and 0.69%, respectively. In two animals delivered by cesarean section, MAC increased progressively over the first 12 h of life. Progesterone levels concomitantly decreased.

Submental orotracheal intubation for maxillofacial surgery.

To the Editor:—Airway management for patients who suffered midfacial fractures is complicated. Tracheostomy and nasotracheal intubation may lead to other complications. Nasal intubation can interfere with centralization and stabilization of nasal fractures. An orotracheal tube may compromise the reduction and maintenance of midfacial fractures. We successfully treated a patient with multiple facial fractures using submental intubation. After a motor vehicle accident, a previously healthy 29-yr-old man sustained nasal and bilateral zygomatic fractures, as well as left maxillary fracture with left orbital blowout. There was no evidence of an intracranial or cervical spine injury. After a regular intravenous anesthetic induction, a #7 endotracheal tube was placed orally. Anesthesia was maintained with isoflurane by inhalation and 100% oxygen. The surgeon made a 1-cm incision halfway between the chin and the angle of the mandible. A Kelly forcep was introduced through the skin incision and into the floor of the mouth by blunt dissection. The forcep was kept close to the inner side of the mandible. Care was taken to avoid the submandibular duct and the lingual nerve, which were medial to the proposed tube entry site. A second Kelly forcep was attached to the first Kelly forcep and brought out through the submental incision. A second #7 endotracheal tube was pulled through the submental incision (cuff end first). The initial orotracheal tube was then removed, and the second endotracheal tube was passed into the trachea (fig. 1). The submental intubation procedure took , 10 min to perform. The operative procedure, in which the multiple fractures were reduced and fixated, proceeded uneventfully. Intermaxillary fixation was preformed without any impediment from the submental orotracheal tube. Anesthesia was discontinued, and the patient was extubated in the operating room after he awakened. The submental incision was not closed. His postoperative course was unremarkable. The submental incision healed with minimal scarring. Tracheal intubation via the submental route was first described by Altemir in 1986. After orotracheal intubation and establishment of the submental tract, the free end of the endotracheal tube was pulled through a submental incision and reconnected to the anesthetic circuit. There are technical problems with the original technique described. Because of the tight seal of the connector with the reinforced (spiral) endotracheal tube, it is difficult to separate the connector and tube during the transfer from the oropharynx through the submandibular tract. Green and Moore reported a modification of Altemir’s approach. The airway was secured with a regular orotracheal tube first. A second endotracheal tube was inserted through the submental route before being exchanged with the previously positioned orotracheal tube. We used the modified technique successfully in our patient with multiple midfacial fractures. The submental orotracheal intubation technique is simple. Further studies with submental orotracheal intubation and tracheostomy are needed to compare the risks and benefits of the techniques.

Obstetrical anaesthesia at Winnipeg Women’s Hospital 1975–83: anaesthetic techniques and complications

RésuméĽexpérience de ľanesthésie obstétricale du Women’s Hospital de Winnipeg de 1975 à 1983 est revue (n = 22,925 enfants). Ľutilisation des narcotiques pour Ľanalgésie lors du travail diminua de 38.7 à 18.3 pour cent. Pour ľanalgésie lors de ľaccouchement vaginal spontané, ľanesthésie epidurale augmenta de 6.0 à 24.0 pour cent, ľanalgésie par agent ďinhalation diminua de 53.7 à 3.2 pour cent alors que pour le groupe où aucune intervention anesthésique nefut nécessaire le pourcentage augmenta de 40.3 à 72.8 pour cent. Ľutilisation de ľanesthésie épidurale pour les césariennes augmenta de 58.7 à 82.6 pour cent. Les complications aigues les plus communes de ľanesthésie furent ľhypotension et la ponction involontaire de la dure-mère lors de la cathétérisation de ľespace épidural. Ľincidence de ľhypotension diminua de 26.3 à 17.4 pour cent au cours de cette période de neuf ans. La ponction de la duremère diminua de 4.7 à 1.1 pour cent pour toute injection épidurale. Les plaintes en période de postpartum (qu’on pense reliées à ľanesthésie) étaient surtout les maux de tête, les dorsalgies et les maux de gorge. Ľincidence de ces plaintes diminuèrent aussi à travers la période de ľétude.

Thoracic versus lumbar epidural fentanyl for postthoracotomy pain

Thirty patients were prospectively randomized to receive either thoracic or lumbar epidural fentanyl infusion for postthoracotomy pain. Epidural catheters were inserted, and placement was confirmed with local anesthetic testing before operation. General anesthesia consisted of nitrous oxide, oxygen, isoflurane, intravenous fentanyl citrate (5 micrograms/kg), and vecuronium bromide. Pain was measured by a visual analogue scale (0 = no pain to 10 = worst pain ever). Postoperatively, patients received epidural fentanyl in titrated doses every 15 minutes until the visual analogue scale score was less than 4 or until a maximum fentanyl dose of 150 micrograms by bolus and an infusion rate of 150 micrograms/h was reached. The visual analogue scale score of patients who received thoracic infusion decreased from 8.8 +/- 0.5 to 5.5 +/- 0.7 (p < or = 0.05) by 15 minutes and to 3.5 +/- 0.4 (p < or = 0.05) by 45 minutes. The corresponding values in the lumbar group were 8.8 +/- 0.6 to 7.8 +/- 0.7 at 15 minutes and 5.3 +/- 0.9 at 45 minutes (p < or = 0.05). The infusion rate needed to maintain a visual analogue scale score of less than 4 was lower in the thoracic group (1.55 +/- 0.13 micrograms.kg-1 x h-1) than in the lumbar group (2.06 +/- 0.19 microgram.kg-1 x h-1) during the first 4 hours after operation (p < or = 0.05). The epidural fentanyl infusion rates could be reduced at 4, 24, and 48 hours after operation without compromising pain relief. Four patients in the lumbar group required naloxone hydrochloride intravenously.(ABSTRACT TRUNCATED AT 250 WORDS)