Airway changes during labor and delivery.

BACKGROUND: There are no prospective studies that evaluated airway changes during labor. The purpose of this study was to evaluate airway changes in women undergoing labor and delivery. METHODS: Two studies were undertaken to evaluate airway changes during labor. The first study used the conventional Samsoon modification of the Mallampati airway class. The airway was photographed at the onset and the end of labor. Women with class 4 airways were excluded from initial participation. In the second study, upper airway volumes were measured using acoustic reflectometry at the onset and the conclusion of labor. Acoustic reflectometry software computed the values for the components of upper airway, oral volume, and pharyngeal volume. RESULTS: In study 1 (n = 61), there was a significant increase in airway class from prelabor to postlabor (P < 0.001). The airway increased one grade higher in 20 (33%) and two grades higher in 3 (5%) after labor. At the end of labor, there were 8 parturients with airway class 4 (P < 0.01) and 30 parturients with airway class 3 or class 4 (P < 0.001). In study 2 (n = 21), there were significant decreases in oral volume (n = 21; P < 0.05), and pharyngeal area (P < 0.05) and volume (P < 0.001) after labor and delivery. No correlation was observed between airway changes during labor and duration of labor, or fluids administered during labor in either study. CONCLUSION: Airways can change during labor. Therefore, a careful airway evaluation is essential just before administering anesthesia during labor rather than obtaining this information from prelabor data.

Recent advances in obstetric anesthesia.

The low-dose technique of combined spinal/epidural analgesia is to be welcomed in obstetrics. Its merits include rapid onset of analgesia, with the flexibility of an epidural technique, and high maternal satisfaction. It is a safe and effective technique. Pulse oximetry should be employed when using intrathecal opioids. Commercially available combined-needle devices may make this technique more attractive to users. The role of spinal anesthesia for emergency cesarean section in severe preeclampsia has been reevaluated recently. We consider it a feasible option for those severely preeclamptic women requiring urgent cesarean section who do not have an epidural catheter in place. The choice of anesthetic technique for this patient population should be made on clinical judgment and not on anticipated hemodynamic changes. Spinal anaesthesia for cesarean section is associated with hypotension; however, certain interventions may reduce the incidence and severity of the hypotension. An increase in cardiac output appears to be key in attenuating the hypotensive response to spinal anesthesia. Colloids have exhibited most success in this regard. At our institution, we do not delay spinal anesthesia for urgent cesarean section in order to administer a predetermined volume of fluid; in such cases, we simultaneously administer a fluid preload and spinal anesthesia. Recent studies regarding the use of cell savers for blood conservation in obstetrics are based on small numbers of patients. These studies show great promise, particularly with the modern emphasis on avoiding blood transfusion, which can be massive in this usually young patient population.

The effect of intrathecal epinephrine on epidural infused analgesics during labor.

BACKGROUND AND OBJECTIVES: In order to prolong labor analgesia, one may add intrathecal epinephrine to the combination of bupivacaine and fentanyl. In this study, we tested the hypothesis that the addition of intrathecal epinephrine would lessen the requirement for a rescue dose of epidural analgesia during labor. METHODS: One hundred-eight parturients randomly received intrathecal bupivacaine 2.5 mg and fentanyl 25 microgram with epinephrine 100 microgram (Group BFE) or without (Group BF). Analgesia was assessed by visual analogue pain score (VAPS) 15 and 30 minutes after drug administration. Then, epidural analgesia (0.1% bupivacaine with 0.0002% fentanyl and 1:250,000 epinephrine at 10 mL/h) was initiated. If the patient requested additional analgesia and VAPS was over 30 mm, we added 8 mL epidural bupivacaine 0.125%. The requirement for additional analgesia, the incidence of motor block assessed by a modified Bromage score, hypotension, nausea, and pruritus was noted. RESULTS: Except for 3 parturients in Group BF, satisfactory analgesia was achieved in all parturients 30 minutes after intrathecal drug administration. Following 30 minutes of intrathecal drug administration, VAPSs (mean +/- SD) were 0 +/- 4 mm in Group BFE and 4 +/- 11 mm in Group BF. The number of patients who required additional labor analgesia in Group BFE (11 patients, 20%) was significantly less than in Group BF (26 patients, 48%) (P =.003). The incidence of motor block 30 minutes after spinal analgesia in Group BFE (12 patients, 22%) was significantly higher than in Group BF (3 patients, 6%) (P =.024). Nausea and pruritus were similar in both groups. CONCLUSION: The addition of epinephrine to intrathecal bupivacaine-fentanyl lessened the requirement for additional epidural analgesia without increasing hypotension, nausea, or pruritus. However, the incidence of motor block may be increased without labor prolongation.

In vitro fertilization-induced alterations in coagulation and fibrinolysis as measured by thromboelastography.

Supraphysiologic increases in estrogen produced by in vitro fertilization (IVF) promote the expression of hemostatic markers. Although quantitative studies of individual markers have been performed during IVF, their results are conflicting and do not reveal the qualitative effect of each marker on the overall coagulation and fibrinolytic processes. Thrombelastograph (TEG) coagulation analysis, by contrast, provides a global measure of coagulation and fibrinolysis and can indicate the relative contributions of clotting factors, fibrinogen, and platelets to each process. We studied the serum estrogen concentrations and TEG variables in 24 women at the beginning and conclusion of an IVF stimulation cycle. Serum estradiol (E(2)) concentrations (mean +/- SD) increased from 26.9 +/- 8.6 to 2098 +/- 913 pg/mL (P < 0.005) at baseline and oocyte retrieval, respectively. The measured TEG indices demonstrated alterations in coagulation rather than fibrinolysis. Although significant changes were noted in both the clot formation time and the coagulation index (P < 0.005), all TEG values remained within the normal range. In addition, an increased role of fibrinogen in promoting clot strength was observed. These findings may assist in the treatment of IVF patients who ultimately develop thromboembolic complications as a result of ovarian hyperstimulation. IMPLICATIONS. The dramatic changes in estrogen produced by in vitro fertilization therapies result in hemostatic marker alterations. Thrombelastograph coagulation analysis, which provides a global assessment of these changes, demonstrated significant alterations in two coagulation indices (clot formation time, coagulation index), although all variables remained within normal limits. The relative importance of fibrinogen versus platelets in determining clot strength was observed. No significant alterations in fibrinolysis were detected.

Anesthetic considerations for a patient with compound heterozygous medium-chain Acyl-CoA dehydrogenase deficiency.

IMPLICATIONS: We describe the anesthetic management of a parturient with compound heterozygous medium chain acyl-CoA dehydrogenase deficiency, the most common disorder of fatty acid metabolism.

Pregnancy alters adrenergic mechanisms in uterine arterioles of rats.

UNLABELLED: Pregnancy is associated with altered vascular reactivity. However, the effect of pregnancy on the alpha- and beta-adrenergic responses in the uterine microcirculation remains to be determined. In late-pregnant (Day 20-21, n = 6) and virgin (n = 6) Sprague-Dawley rats, uterine radial arterioles (70-120 microm in internal diameter) were isolated. We studied in vitro arteriolar responses in a pressurized, no-flow state with videomicroscopy. alpha(2)-Adrenergic activation relaxed uterine arterioles; this relaxation was increased with pregnancy and was inhibited after endothelial denudation or inhibition of nitric oxide synthase. Pregnancy significantly increased the contractile response to the alpha(1)-adrenoceptor agonist phenylephrine but decreased the relaxation to the beta-adrenoceptor agonist isoproterenol. The contractile response to the protein kinase C activator phorbol ester and relaxation responses to both the adenylate cyclase activator forskolin and the endothelium-independent cyclic guanosine monophosphate-mediated vaso- dilator nitroprusside were preserved. These results suggest that pregnancy enhances the alpha(2)-adrenoceptor-mediated relaxation of uterine arterioles, probably because of an increase in the release of nitric oxide. The alpha(1)-adrenergic response is upregulated, whereas the beta-adrenergic response is impaired, in the uterine microcirculation of pregnant rats. IMPLICATIONS: Both alpha- and beta-adrenergic responses are important mechanisms for the regulation of uteroplacental perfusion. By use of an in vitromicrovascular technique, we have shown pregnancy-associated alteration in adrenergic responses in the uterine microcirculation of the rat.

The effectiveness of video technology as an adjunct to teach and evaluate epidural anesthesia performance skills.

BACKGROUND: Although video review has been used in teaching, it has not been reported for use as an adjunct to teaching anesthesiology residents. The purpose of the prospective, randomized, blinded study was to determine whether teaching with video review improves epidural anesthesia skills of anesthesiology residents. METHODS: Twenty-two second-year (CA-2) anesthesiology residents beginning their first obstetric anesthesia rotation were assigned to video or non-video groups. All residents were filmed daily as they placed epidural analgesia. Residents assigned to the video group reviewed their tapes twice a week with an attending anesthesiologist, whereas residents assigned to the non-video group never saw their films. Four experienced attending anesthesiologists independently judged videotapes taken on days 1, 15, and 30 and scored the residents for "overall" skill (range of summed overall grades, 0-40), as well as on 13 predetermined criteria. RESULTS: As determined by kappa coefficients, interrater reliability was high among the judges (k = 0.7-0.8). Residents in the video group improved to a greater degree than residents in the non-video group. On day 1, the median overall grades for the video and non-video groups were 21 and 12, respectively. By day 15, the corresponding grades had increased to 32 and 24, respectively (P < 0.01). However, overall median grades continued to improve between days 15 and 30 in the video group only (P < 0.01). CONCLUSIONS: Review of resident videotapes resulted in greater improvement in overall and predetermined performance criteria. In addition, video review was helpful in identifying skills that were inadequately learned, thus allowing for specific teaching in those areas.