Virtual airway simulation to improve dexterity among novices performing fibreoptic intubation.

We developed a virtual reality software application (iLarynx) using built-in accelerometer properties of the iPhone(®) or iPad(®) (Apple Inc., Cupertino, CA, USA) that mimics hand movements for the performance of fibreoptic skills. Twenty novice medical students were randomly assigned to virtual airway training with the iLarynx software or no additional training. Eight out of the 10 subjects in the standard training group had at least one failed (> 120 s) attempt compared with two out of the 10 participants in the iLarynx group (p = 0.01). There were a total of 24 failed attempts in the standard training group and four in the iLarynx group (p < 0.005). Cusum analysis demonstrated continued group improvement in the iLarynx, but not in the standard training group. Virtual airway simulation using freely available software on a smartphone/tablet device improves dexterity among novices performing upper airway endoscopy.

Placenta previa: a 22-year analysis.

OBJECTIVE: Our purpose was to identify what anesthetic method is safer for women with a placenta previa. STUDY DESIGN: We retrospectively reviewed all women with placenta previa who underwent cesarean delivery during the period January 1, 1976-December 31, 1997 at Northwestern Memorial Hospital. RESULTS: Of 93,384 deliveries, placenta previa was found in 514 women. Identifiable trends with time included an increasing incidence of placenta previa (r = 0.54, P <.01); cesarean hysterectomy (r = 0.54, P <.01); placenta accreta (r = 0.45, P <.03); and regional anesthesia (r = 0.84, P <.0001). The mean gestational age at delivery was 35.3 +/- 3.4 weeks and did not change with time. General anesthesia was used for delivery in 380 women and regional anesthesia was used for 134 women. Prior cesarean delivery and general anesthesia were independent predictors of the need for blood transfusion, but only prior cesarean delivery was a predictor of the need for hysterectomy. General anesthesia increased the estimated blood loss, was associated with a lower postoperative hemoglobin concentration, and increased the need for blood transfusion. Elective and emergent deliveries did not differ in estimated blood loss, in postoperative hemoglobin concentrations, or in the incidence of intraoperative and anesthesia complications. Regional and general anesthesia did not differ in the incidence of intraoperative and anesthesia complications. CONCLUSIONS: In women with placenta previa, general anesthesia increased intraoperative blood loss and the need for blood transfusion. Regional anesthesia appears to be a safe alternative.

Acoustic reflectometry and endotracheal intubation.

To determine whether acoustic reflection measurement of the upper airway can be used to identify tracheas that are difficult to intubate, we conducted a pilot study of adults with a documented history of unexpected failed endotracheal intubation (16 cases) and compared them with 16 controls with previous successful intubation. The two groups were matched by age, sex, height, and weight. Acoustic reflection measurements of airway cross-sectional area versus distance were made at six combinations of body (upright and supine) and neck (flexed, neutral, and extended) positions. Cumulative airway volumes were calculated from the incisors to the glottis, and these were subdivided into oral and pharyngeal volumes. For supine position with the neck extended, all patients who had been successfully intubated had pharyngeal volumes more than 43.4 mL (mean +/- SD, 56.9 +/- 8.3 mL), whereas pharyngeal volumes were less than 37.5 mL in all patients who had a history of unexpected failed intubation (mean +/- SD, 19.7 +/- 10.2 mL; P < 0.05). Using a cutoff of 40.2 mL, acoustic reflection enabled us to distinguish between patients with previous unexpected failed endotracheal intubation and those with previous successful intubation.

Comparison of thrombelastography with common coagulation tests in preeclamptic and healthy parturients.

BACKGROUND AND OBJECTIVES: Epidural analgesia/anesthesia is often beneficial in the management and treatment of preeclampsia. However, some preeclamptic patients have a coagulopathy that is a contraindication to regional anesthesia. A routine coagulation battery (RCB) consisting of prothrombin time, partial thromboplastin time, platelet count, and bleeding time, is commonly performed to assess coagulation status. Thrombelastography (TEG) is a measure of clotting that allows evaluation of overall coagulation activity. The goal of this study was to examine whether TEG can predict normal and abnormal coagulation as diagnosed by RCB in healthy and preeclamptic parturients. METHODS: Forty-seven parturients participated in this prospective study, performed early in the first stage of labor. Twenty healthy parturients (group I), 19 mild (group II), and 8 severe preeclamptic/eclamptic parturients (group III) had RCB and TEG performed. RESULTS: Five patients (1, group I; 3, group II; 1, group III) had a normal RCB, but a mildly abnormal TEG (prolonged K, small alpha) (specificity = 0.88). Five of 27 preeclamptic parturients (1, group II; 4, group III) had abnormal RCBs. Three of these 5 patients had thrombocytopenia with normal bleeding times and TEGs. Two patients had thrombocytopenia and prolonged bleeding times and abnormal TEGs (sensitivity = 0.40). CONCLUSION: Thrombelastography is not an effective means of predicting abnormal coagulation, as diagnosed by RCB, in preeclamptic parturients, using currently defined normal TEG values for nonpregnant patients. However, an abnormal TEG maximum amplitude value always correlated with a prolonged bleeding time. Therefore, TEG may be useful in assessing platelet function in the presence of thrombocytopenia. Further studies are warranted.

Placenta accreta is associated with elevated maternal serum alpha-fetoprotein.

OBJECTIVE: To determine whether placenta accreta/percreta/increta is associated with elevation of second-trimester maternal serum alpha-fetoprotein (MSAFP) levels. METHODS: We reviewed the medical records of 44 women who had emergency cesarean hysterectomy. Twenty women had placenta accreta/percreta/increta (study group) and 24 underwent cesarean hysterectomy for other indications (control group). Pertinent maternal and neonatal variables were abstracted from the prenatal records and hospital charts. Chi-square and Fisher exact tests were used to analyze categorical variables. Student t test was used to analyze continuous variables. RESULTS: Nine of 20 patients (45%) with placenta accreta/percreta/increta and none of 24 subjects in the control group had an elevated MSAFP value (P < .001). Maternal estimated blood loss was also significantly greater in the study group (4469 +/- 1851 versus 1885 +/- 1113 mL; P < .0001), as was the number of blood units transfused (7.7 +/- 4.7 versus 3.0 +/- 2.2; P < .001). None of the other examined variables were different between the groups. CONCLUSIONS: A significant association exists between placenta accreta/percreta/increta and elevated MSAFP values. Patients with an unexplained elevation of MSAFP may have an increased risk for placenta accreta and associated blood loss at cesarean hysterectomy.

Anaesthetic management of a parturient with myocardial infarction related to cocaine use.

Cocaine abuse is common among parturients with an incidence of 11.8 to 20%. Myocardial infarction is a rare and lethal event during pregnancy with an incidence of 1 in 10,000 pregnancies. We present the anaesthetic management of a parturient of 36 wk gestation who suffered a myocardial infarction nine hours before delivery which was temporally related to "crack" cocaine use. The patient's cardiovascular system became unstable following cocaine use, and she required mechanical ventilatory support and pharmacologic stabilization guided by invasive haemodynamic monitoring. This patient survived a non-Q wave myocardial infarction, but the prognosis of peripartum myocardial infarction remains poor with a mortality rate of 30-40% which is increased if the infarction occurs in the third trimester or postpartum period. The optimal mode and timing of delivery after myocardial infarction is unresolved. The association between cocaine use and myocardial infarction was first described in 1982, and cocaine remains unique among local anaesthetics in its ability to compromise the cardiovascular system through both sympathomimetic effects and vasoconstrictive effects on coronary arteries. Because of the prevalence of substance abuse, cocaine use should be considered in the differential diagnosis of sudden cardiovascular compromise in parturients.

Comparison of cimetidine (Tagamet) with antacid for safety and effectiveness in reducing gastric acidity before elective cesarean section.

One hundred twenty-six parturients for elective cesarean section under general anesthesia were allocated to either a cimetidine or an antacid group in a randomized, double-blind, multicenter trial. The cimetidine-treated group received 300 mg cimetidine orally the evening before the operation and 300 mg intramuscularly between 1 and 3 h preoperatively. The antacid-treated group received 30 ml of Mylanta-II orally on both occasions. Gastric volume, 30 min after induction of anesthesia and 30 min before response to oral commands, was less in the cimetidine-treated group. Gastric pH 30 min after induction was greater in the cimetidine-treated group. The maternal serum level of cimetidine at birth was 1.31 +/- 0.12 micrograms/ml and the umbilical venous level was 0.78 +/- 0.05 micrograms/ml. The neonatal gastric acidity, Apgar scores, and Early Neonatal Neurobehavioral Scale (ENNS) scores were similar in both groups. No maternal or neonatal complication was attributed to treatment.