Fiberoptic intubation using anesthetized, paralyzed, apneic patients. Results of a resident training program.

BACKGROUND: There is no consensus about the best way to teach fiberoptic intubation. This study assesses the effectiveness of a training program in which novice anesthetic residents routinely were taught fiberoptic tracheal intubation of anesthetized, paralyzed, apneic patients. METHODS: Eight inexperienced anesthetic residents learned fiberoptic and conventional tracheal intubation simultaneously during their first 4 months of training. All intubations were performed using general anesthesia and muscle paralysis. Of these intubations, 223 (23%) were fiberoptic and 743 (77%) were laryngoscopic. Subsequently, their intubation skills with the two techniques were studied in a prospective, single-blind randomized trial involving 131 elective patients. Intubation times, SpO2, ETCO2, hemodynamic changes on intubation, and complications were recorded for 71 fiberoptic and 57 laryngoscopic intubations. RESULTS: There were two failures of the rigid and one failure of the fiberoptic technique due to inability to intubate within 180 s. In cases of failure, the tracheas were intubated successfully after mask ventilation by the alterative technique. No hypoxemia or hypercarbia occurred in any patient. There were no differences in hemodynamic indexes nor incidence of sore throat or hoarseness between the two groups. Mean intubation times were 56 +/- 24 s (mean +/- SD) for fiberoptic and 34 +/- 10 s (mean +/- SD) for laryngoscopic (P < 0.001). CONCLUSIONS: Novices taught fiberoptic intubation and rigid laryngoscopic intubation under similar conditions, with similar volumes of experience, learn both techniques well. The safety and effectiveness of this training regimen commend it for inclusion in any residency program.

Hysteroscopy and anaesthesia.

PURPOSE AND SOURCE: Hysteroscopy has become a widely accepted technique in the diagnosis and treatment of various gynaecological conditions. The advent of the fibreoptic endoscope and distending media has largely been responsible for the increasing use of hysteroscopy. It is our aim in this article to review the literature on the frequently used distending media such as carbon dioxide, glycine, dextran, dextrose, sorbitol and mannitol and their anaesthetic implications. PRINCIPAL FINDINGS: The endoscopist chooses the particular medium. Complications due to the distending media occur in < 4% of cases. Dilutional hyponatraemia and hypothermia are commonly encountered complications and, in addition, hyperglycaemia and volume expansion can occur. Less commonly encountered complications are embolism with carbon dioxide and pulmonary oedema, renal failure and in rare cases anaphylaxis and encephalopathy. Regional anaesthesia may offer an advantage over general anaesthesia in early recognition of fluid accumulation. Apropriate monitoring should include fluid balance, routine monitoring as well as temperature, electrolytes and blood sugar measurements. Precordial Doppler measurement, central venous and/or pulmonary artery pressure measurement may be of help in detecting as well as treating carbon dioxide and/or air embolism and fluid balance in high risk patients. CONCLUSIONS: There is no one commonly used medium and no one medium is devoid of complications. There have been no controlled studies comparing different anaesthetic techniques. Positioning of the patient can give rise to complications such as peripheral neuropathy. Hysteroscopy is a non invasive procedure which entails a short hospital course with minimal postoperative sequelae and may be cost saving.

Alternating nitroglycerin and syntocinon to facilitate uterine exploration and removal of an adherent placenta.

Nitroglycerin (NTG) has been demonstrated to provide uterine relaxation in the management of various obstetric complications. A 32-yr-old woman presented 40 min postpartum for manual removal of a retained placenta. Repeated, alternating doses of NTG 250 micrograms and syntocinon (SYN) 10U iv were used over 15 min to produce periods of uterine relaxation and contraction respectively for uterine exploration. Multiple attempts to extract the placenta failed and a diagnosis of placenta accreta was made. There were no major side effects from this combination of drugs apart from a transient 20% decrease in blood pressure after NTG, which responded to ephedrine 10-15 mg iv. The rapid change in uterine tone was believed to be due not only to the short duration of action of NTG and SYN, but also to the possible physiological antagonism between the two drugs. The mechanism of interaction may involve calcium mobilization and myosin light chain phosphorylation. We conclude that NTG and SYN can be used to produce alternating periods of uterine relaxation and contraction rapidly and consistently with little sustained effects from either agents.

The premature infant: anesthesia for cesarean delivery.

The influence of anesthetic technique (general [GA] versus epidural [EPI]) on neonatal outcome was assessed for singleton infants of gestational age 32 wk or less, delivered by cesarean section. Neonates were identified from a prospectively collected perinatal database from 1986 to 1991. The independent effect of anesthetic technique on low 1-min Apgar scores after controlling for other risk factors was assessed by ordinal logistic regression. Among the 509 infants studied, 30% had Apgar scores of 0 to 3 at 1 min and 5.9% at 5 min. Among infants delivered with GA, 46.4% had low 1-min and 10.1% had low 5-min Apgar scores as compared to 22.0% and 3.8% for EPI. GA as compared to EPI was associated with higher risk of low (0-3) 1-min score after controlling for confounding factors (relative odds = 2.92, [1.99, 4.27 95% confidence intervals]). Other factors significantly related to low 1-min Apgar scores included malpresentation, maternal diabetes, primiparity, low gestational age, and associated neonatal outcomes (presence of respiratory distress syndrome and intraventricular hemorrhage). When there is a choice to be made in cesarean delivery of the premature infant, EPI is associated with higher 1- and 5-min Apgar scores compared to GA.

Acute intermittent porphyria and caesarean delivery.

A 29-yr-old patient was diagnosed with acute intermittent porphyria (AIP) during pregnancy. She had a Caesarean section under lidocaine/fentanyl epidural blockade. Because of inadequate analgesia, general anaesthesia was induced with propofol. Postoperatively urinary porphobilinogen excretion (625 mumol.day-1) exceeded the upper limit of normal but no symptoms of porphyria developed. In anecdotal clinical reports and in a previously described rat model of porphyria, propofol was found to be safe. This is the first reported use of propofol in a pregnant porphyric patient. Anaesthetic drug safety in porphyria is reviewed and the choice of induction agent discussed. Data on which to base these decisions is limited but we conclude that propofol may be suitable for use in patients with porphyria.

Epidural anesthesia, episiotomy, and obstetric laceration.

The relationships among epidural anesthesia, forceps use, parity, episiotomy, and laceration were studied in 9493 uncomplicated vertex deliveries of spontaneous onset and normal course. The use of epidural anesthesia was not associated with an increased incidence or severity of birth-canal trauma. Episiotomy was associated with a decreased rate of perineal laceration, but an overall increase in the rate of perineal trauma. The trauma that did occur with episiotomies was four times more likely to be major than that when no episiotomy was performed.

Epidural anesthesia for obstetrics after spinal surgery.

The experience of 18 patients with previous spinal surgery who requested epidural anesthesia for obstetric pain was reviewed. Three received epidural anesthetics in two separate pregnancies, producing a total of 21 attempts at epidural anesthesia. All were initiated during labor and three were later extended for Cesarean delivery. Continuous lumbar epidural anesthesia was successfully established in 20 of 21 attempts. Ten were performed easily on the first attempt. There were excessive local anesthetic requirements and/or a patchy block for the remaining 11 attempts. The only complication that could be attributed to the attempts at epidural anesthesia was temporary low back pain in two patients with multiple attempts. No complications were noted on long-term follow-up. Our data, therefore, suggest that epidural anesthesia is safe and generally effective in obstetric patients with previous spinal surgery.

Fluid through the epidural needle does not reduce complications of epidural catheter insertion.

Epidural catheter insertion may be associated with blood vessel trauma or nerve root irritation. The purpose of this study was to assess whether the injection of small amounts of fluid through the Tuohy needle prior to catheter insertion reduced the incidence of these and other minor complications. Two hundred patients in labour, requesting epidural analgesia, were randomly assigned to one of three groups: Group I--the catheter was inserted without previous injection of fluid; Group II--3 ml, 1.5 per cent lidocaine hydrochloride was injected through the needle prior to catheter insertion; Group III--3 ml, saline was injected prior to catheter insertion. There were no differences among the groups in the incidence of blood vessel trauma or paraesthesiae. We conclude that there is no advantage in injecting of fluid routinely into the epidural space prior to catheter insertion.

Epidural anaesthesia for caesarean section in patients with active recurrent genital herpes simplex infections: a retrospective review.

The safety of epidural anaesthesia in patients with active, recurrent genital herpes simplex (HSV) infections is controversial. We reviewed the six-year experience of the use of epidural anaesthesia in this patient population in two institutions. Eighty-nine parturients with active genital HSV were administered epidural anaesthesia for Caesarean section. No patient suffered an adverse outcome related to either the anaesthetic or the virus. The theoretical risks of regional anaesthesia in the parturient with active herpes genitalis are reviewed. We conclude from available data that the risk of an adverse outcome is small and does not contraindicate the use of epidural anaesthesia in patients with recurrent infection.

Epidural anaesthesia and blood flow velocity in mother and fetus.

Doppler ultrasound has recently been used to assess changes in blood velocity in the uterine and umbilical arteries. Alterations in the ratio of systolic to diastolic velocity (S/D ratio) are believed to reflect changes in placental vascular resistance. We have used this technique to assess potential beneficial or detrimental effects of epidural anaesthesia on blood flow to the placenta. Continuous wave Doppler ultrasound was used to measure the S/D ratio in the uterine and umbilical arteries of 12 patients undergoing epidural anaesthesia prior to elective caesarean section. Anaesthesia was achieved using lidocaine and epinephrine. The S/D ratio in both the uterine and umbilical arteries remained unaltered either by the fluid preload or by the epidural anaesthesia. It is concluded that epidural anaesthesia using this technique has neither a beneficial nor detrimental effect on uterine or umbilical blood velocity in the uncomplicated pregnancy.

Epidural anaesthesia and thrombocytopenia.

A case is presented of a mother with unanticipated profound thrombocytopenia who received a continuous epidural anaesthetic for labour. No neurological sequelae or excessive bleeding occurred. It is clear, after a review of the literature, that more information is needed to define the lower limits of platelet count at which it is safe to proceed with epidural anaesthesia.

Epidural anesthesia in pregnant patients with low platelet counts.

A number of patients demonstrate thrombocytopenia in the peripartum period. One hundred four patients with unexplained transient periparturient thrombocytopenia were found over a nine-month period. Sixty-one of them received epidural anesthesia without neurologic sequelae. Epidural anesthesia is safe if the platelet count exceeds 100 x 10(9)/L in otherwise healthy women.