Theodore G. Cheek

Anesthesia for nonobstetric surgery: maternal and fetal considerations.

This monograph will review and update our understanding of the administration of anesthesia for nonobstetric surgery and its maternal and fetal effects. It begins with a summary of the subject and a short review of maternal physiologic changes during pregnancy with an emphasis on their anesthetic implications. Attention will be paid to a review of the literature and meta-anlyses that crystallize our understanding of fetal vulnerability to teratogenicity and the evidence for and against anesthetic effects in this regard. Recent reports of anesthetic effects on fetal and neonatal rat neural function will be reviewed and commented on. Fertility and pregnancy retention after anesthetic administration will be surveyed and a short update on the risks experienced by operating room personnel exposed to environmental anesthetics will be covered. The question of whether to and when to monitor the fetus during nonobstetric surgery will be discussed with some suggested guidelines. Special surgical situations such as laparoscopy, cardiac surgery, trauma, and fetal therapy will also be discussed. The conclusion contains clinical suggestions for the approach to anesthetizing the pregnant patient.

Anesthetic management of cesarean delivery complicated by ex utero intrapartum treatment of the fetus

W ith recent developments in prenatal imaging, fetal anatomic malformations involving the airway that would previously have caused difficulty during delivery and in the postpartum period are now diagnosed antenatally. These cases present challenges not only for the obstetrician and pediatric surgeon but also for the anesthesiologist. Maternal and fetal anesthesia and safety as well as uterine relaxation must be considered in formulating an anesthetic plan. We present three cases of anesthetic management for ex utero intrapartum treatment (EXIT procedure) (1). This procedure was used to establish an airway before delivery of two fetuses with large neck masses and in one fetus for removal of a tracheal clip placed at 28 weeks for the antenatal treatment of a diaphragmatic hernia.

Comparison of combined spinal-epidural and low dose epidural for labour analgesia.

Purpose: To compare the combined spinal-epidural (CSE) technique with the epidural technique with regard to time to initiate and manage, motor block, onset of analgesia and satisfaction during labour.Methods: Upon requesting analgesia, 50 healthy term parturients were randomized in a prospective, double-blind fashion to receive either CSE analgesia or lumbar epidural analgesia in the labour floor of a university hospital at an academic medical centre. The epidural group (n=24) received bupivacaine 0.0625%-fentanyl 0.0002% with 0.05 ml in 10 ml local aesthetic sodium bicarbonate 8.4% and epinephrine 1:200, 000. The CSE group (n=26) received intrathecal 25 µg fentanyl and 2.5 mg bupivacaine. Additional analgesia was provided upon maternal request.Results: There were no differences (P>0.05) in time of perform either technique, motor blockade, or parturient satisfaction or in the number of times that the anesthesiologist was called to perform any intervention. Although the first sign of analgesia was not different between the two groups, the onset of complete analgesia was more rapid with the CSE technique (Visual Analogue Pain Score (VAPS) at five minutes<three: 26/26vs 17/24,P±0.001).Conclusion: Although epidural analgesia with a low concentration of local anethetic and opioid mixture takes longer to produce complete analgesia, it is a satisfactory alternative to CSE.RésuméObjectif: Comparer l’analgésie rachidienne-péridurale combinée (RPC) à l’analgésie péridurale concernant le temsp nécessaire à la réalisation de la technique et à l’induction, le blocage moteur, le délai d’installation de l’analgésie et la satisfaction de la patiente pendant le travail obstétrical.Méthode: Au moment de la demande d’analgésie, 50 parturientes à terme réparties de façon aléatoire ont reçu soit une analgésie RPC, soit une analgésie péridurale lombaire pour participer à une étude prospective en double insu. Le groupe péridural (n=24) a reçu un mélange bupivacaïne 0,0625 %-fentanyl 0,0002 % avec un ajout de 0,05 ml (par 10 ml d’anesthésique local) de bicarbonate de sodium à 8,4 % et de l’épinéphrine 1:200 000. Le groupe RPC (n=26) a reçu une injection intrathécale de 25 µg de fentanyl et de 2,5 mg de bupivacaïne. L’analgésie supplémentaire a été administrée sur demande.Résultats: Il n’y a eu aucune différence intergroupe (P>0,05) quant au temps nécessaire à la réalisation de chacune des techniques et à l’atteinte du blocage moteur, à la satisfaction des patientes et au nombre d’interventions de l’anesthésiologiste appelé sur demande. Le premier signe d’analgésie est survenu au même temps dans les deux groupes, mais le début de l’analgésie complète est survenu plus rapidement dans le groupe RPC (Score à l’Échelle Visuelle Analogique, SEVA, à cinq minutes<trois: 26/26vs 17/24,P±0,001).Conclusion: L’analgésie péridurale complète réalisée avec une faible concentration d’anesthésique local et un mélange d’opioïdes connaît une installation plus lente que l’analgésie RPC, mais elle en constitue une solution de remplacement satisfaisante.

Comparison of three different doses of intrathecal fentanyl and sufentanil for labor analgesia

STUDY OBJECTIVE To compare the duration of analgesia and incidence of side effects of three doses of intrathecal fentanyl (25 micrograms, 37.5 micrograms, 50 micrograms) with three doses of intrathecal sufentanil (5 micrograms, 10 micrograms, 15 micrograms). DESIGN Randomized, double-blind study. SETTING Labor suite of the Hospital of the University of Pennsylvania. PATIENTS 60 ASA physical status I and II parturients in active labor who requested analgesia. INTERVENTIONS Patients received one of the six doses of opioid diluted with normal saline to achieve a volume of 1.5 ml intrathecally. MEASUREMENTS AND MAIN RESULTS Duration of analgesia, contraction pain, degree of pruritus, maternal blood pressure, maternal heart rate, fetal heart rate, Apgar scores, and neurologic and adaptive capacity scores were measured. There was no statistical difference among the doses of fentanyl in duration of analgesia. In addition, there was no statistical difference among the doses of sufentanil. The durations of analgesia for all doses of sufentanil were statistically longer than that for all doses of fentanyl. There was no difference among all the groups for maximal pruritus score. The duration of pruritus did not differ among doses of fentanyl or sufentanil; the duration of pruritus was significantly longer for sufentanil. All groups had a decrease in blood pressure. There was no difference among the groups in regard to the effect on the systolic or diastolic blood pressure. CONCLUSIONS Intrathecal sufentanil produced analgesia of longer duration than fentanyl for all doses studied. The duration of pruritus with sufentanil was also longer.

Epidural lidocaine versus 2-chloroprocaine for fetal distress requiring urgent cesarean section

Chloroprocaine is a local anesthetic widely used for the urgent cesarean delivery of a distressed fetus in an mother with a epidural catheter because of its quick onset and short half-life. However, chloroprocaine has disadvantages that include decreased effectiveness of subsequently administered epidural amides and narcotics. Lidocaine with freshly added epinephrine and sodium bicarbonate is also rapid in onset, although there is the theoretical concern regarding the accumulation of ionized lidocain in the acidotic fetus. A retrospective review revealed that though the drug administration to incision time was significantly faster (P < 0.005) for 3% chloroprocaine, both 3% chloroprocaine and 1.5% lidocaine were clinically effective. There were no differences in neonatal Apgar scores or neonatal umbilical cord pH values between the two treatment populations, offering lidocaine as an attractive alternative to chloroprocaine.

Effects of immediately initiating an epidural infusion in the combined spinal and epidural technique in nulliparous parturients

Background and Objectives: Intrathecal fentanyl with bupivacaine provides rapid labor analgesia of limited duration. We investigated the effect of initiating an epidural infusion of 0.1% ropivacaine with fentanyl 2 μg/mL and epinephrine 1:400,000 (REF) on the duration of analgesia and incidence of side effects after intrathecal injection in the combined spinal and epidural technique. Methods: Thirty‐four nulliparous parturients with a cervical dilation of 3 to 5 cm were randomized to receive epidural saline or REF at 10 mL following the intrathecal injection of fentanyl 25 μg and bupivacaine 2.5 mg. Degree of analgesia, severity of pruritus, motor block, blood pressure, and sensory level to coolness were assessed until the patient requested additional analgesia. Results: Analgesia was significantly longer in the REF group, 158.4 ± 59.6 minutes versus 103.8 ± 26.2 minutes. The decrease in blood pressure compared with the blood pressure at intrathecal injection was greater for the REF group at all times, but achieved statistical significance at 60 minutes. There was no difference in ephedrine use, pruritus, or motor block between groups. There was no difference in sensory level to coolness at 90 minutes after intrathecal injection between groups. Conclusions: Initiating an infusion of REF prolongs the duration of analgesia, but also results in a greater decrease in blood pressure. Despite this effect on blood pressure, there was no difference in ephedrine use.

AIRWAY MANAGEMENT IN THE OBSTETRIC PATIENT

In summary, the need to manipulate the airway in the pregnant patient requires careful consideration and substantial planning. Anatomic and physiologic changes of pregnancy, coexisting conditions, and the potential for aspiration all carry a risk of morbidity and, indeed, mortality. Preparation, including early and repeated airway evaluations throughout pregnancy and labor, is encouraged. Knowledge of an emergency airway algorithm and a well thought-out plan for difficult intubations are imperative. Equipment must be available and in good condition. Finally, proper education and review for individuals involved in the delivery of care on the labor floor are mandatory. Although it is not always possible to control the manner in which these patients present, it is usually possible to control the environment into which they present.

The Zavanelli maneuver does not preclude regional anesthesia

S houlder dystocia occurs in 0.23%-2.09% of all vaginal deliveries and is a true obsketrical emergency (1). Risk factors include maternal obesity, diabetes mellitus, postdates pregnancy, fetal macrosomia, prolonged second stage of labor, oxytocin induction, and instrumental extraction (2,3). There are several maneuvers for the management of shoulder dystocia, which occurs during the second stage of labor or delivery. These include application of suprapubic pressure posteriorly (Mazzanti maneuver), flexing the legs onto the abdomen (McRoberts maneuver), rotational maneuver of the shoulder girdle (Wood’s screw rotational maneuver) (4,5), and cephalic replacement (Zavanelli maneuver) (6,7). Effective regional anesthesia will facilitate these maneuvers and enhance maternal cooperation. The Zavanelli maneuver involves manually replacing the feral head into the relaxed uterus followed by cesarean section. Recommendations to provide uterine relaxation include either deep general anesthesia or tocolysis with intravenous (IV) or subcutaneous terbutaline (1,8,9). We present a case in which the Zavanelli maneuver was performed under epidural anesthesia with uterine relaxation provided by amyl nitrite inhalation.

Epidural anesthesia and the progress of labor.

Epidural block remains the most effective, safe approach to pain relief for labor, and demand for its use continues to grow. Opposition to epidural block in labor, based on a widely acclaimed 1993 study, has led to the widespread discouragement of its use for laboring women and the denial of payment to some anesthesiologists who use it. Within the past year, strong evidence has emerged showing that the association of epidural block with dystocia and cesarean section is casual and not causal.

Patient Variables and the Subarachnoid Spread of Hyperbaric Bupivacaine in the Term Patient

To determine if age, height, weight, body mass index, or vertebral column length significantly influence the distribution of sensory analgesia or anesthesia after subarachnoid injection of hyperbaric bupivacaine, 52 women presenting for cesarean section were studied. All received 15 mg hyperbaric bupivacaine via subarachnoid injection at L-2 or L-3. Fifteen minutes after injection, while the women lay supine on a horizontal operating table, the maximum cephalad extent of sensory analgesia (loss of sensation of sharpness to pin prick) and anesthesia (loss of sensation of light touch) was determined. Age (20-42 yr), height (146.9-174.0 cm), weight (55.5-136.4 kg), body mass index (19.2-50.0 kg/m2), and vertebral column length (49.6-67.0 cm) did not correlate with the spread of sensory blockade. In conclusion, in parturients of age, height, weight, body mass index, and vertebral column length within the aforementioned ranges, it is not necessary to vary the dose of injected hyperbaric bupivacaine with changes in any of the patient variables studied.