A survey of the management of spinal-induced hypotension for scheduled cesarean delivery

BackgroundIntravenous fluids and vasopressors are used for managing spinal-induced hypotension during cesarean delivery, but the choice of vasopressor and the type and timing of fluid administration remain controversial.MethodsWe conducted an electronic survey of all members of the Society for Obstetric Anesthesia and Perinatology between February and March 2007 to determine their preferences for preventing and treating spinal-induced hypotension with respect to fluid and vasopressor administration.ResultsThe response rate was 292/746 (39%). Fifty percent worked in academic institutions and 56% had >50% of their clinical responsibility to obstetric anesthesia. For prophylaxis, 35% used fluid preloading, 30% fluid preloading with vasopressors, and 12% fluid co-loading with vasopressors. Of those using vasopressors for prophylaxis, 32% used ephedrine, 26% used phenylephrine, and 33% based their choice on heart rate. For treatment, 32% used ephedrine, 23% used phenylephrine, and 41% used either agent based on heart rate. Anesthesiologists in academic practice were less likely to use fluid preloading only (P = 0.028) and more likely to use fluid co-loading and vasopressors (P = 0.003). They were also more likely to administer phenylephrine for prophylaxis compared with those in private practice (P = 0.042).ConclusionSignificant variations in practice exist in the prevention and treatment of spinal-induced hypotension. Fluid preloading and the prophylaxis and treatment of hypotension with ephedrine continue to be common practices.     

An open-label randomized controlled clinical trial for comparison of continuous phenylephrine versus norepinephrine infusion in prevention of spinal hypotension during cesarean delivery

BackgroundDuring spinal anesthesia for cesarean delivery phenylephrine is the vasopressor of choice but can cause bradycardia. Norepinephrine has both β- and α-adrenergic activity suitable for maintaining blood pressure with less bradycardia. We hypothesized that norepinephrine would be superior to phenylephrine, requiring fewer rescue bolus interventions to maintain blood pressure.MethodsEighty-five parturients having spinal anesthesia for elective cesarean delivery were randomized to Group P (phenylephrine 0.1 μg/kg/min) or Group N (norepinephrine 0.05 μg/kg/min) fixed-rate infusions. Rescue bolus interventions of phenylephrine 100 μg for hypotension, or ephedrine 5 mg for bradycardia with hypotension, were given as required to maintain systolic blood pressure. Maternal hemodynamic variables were measured non-invasively.ResultsThere was no difference between groups in the proportion of patients who required rescue vasopressor boluses (Group P: 65.8% [n=25] vs. Group N: 48.8% [n=21], P=0.12). The proportion of patients who received ⩾1 bolus of phenylephrine was similar between groups (Group P: 52.6% [n=20] vs. Group N: 46.5% [n=20], P=0.58). However, more patients received ⩾1 bolus of ephedrine in the phenylephrine group (Group P: 23.7% [n=9] vs. Group N: 2.3% [n=1], P <0.01). The incidence of emesis was greater in the phenylephrine group (Group P: 26.3% vs. Group P: 16.3%, P <0.001). Hemodynamic parameters including heart rate, the incidence of bradycardia, blood pressure, cardiac output, cardiac index, stroke volume, and systemic vascular resistance and neonatal outcome were similar between groups (all P <0.05).ConclusionNorepinephrine fixed-rate infusion has efficacy for preventing hypotension and can be considered as an alternative to phenylephrine.     

Optimal intrathecal hyperbaric bupivacaine dose with opioids for cesarean delivery: a prospective double-blinded randomized trial

BackgroundSingle-shot spinal anesthesia is commonly used for cesarean delivery. Achieving adequate anesthesia throughout surgery needs to be balanced with associated complications. We investigated the optimal dose of intrathecal hyperbaric bupivacaine, co-administered with opioids, for anesthesia for cesarean delivery.MethodsThis prospective, randomized, double-blinded, dose-ranging trial included parturients scheduled to undergo cesarean delivery under spinal anesthesia. An epidural catheter was first inserted at the T11–12 vertebral interspace, followed by spinal anesthesia at the L2–3 or L3–4 vertebral interspace. Subjects were randomly assigned to one of seven doses of intrathecal hyperbaric bupivacaine 0.5% (6, 7, 8, 9, 10, 11 or 12 mg), with added 15 μg fentanyl and 75 μg morphine. Successful induction of anesthesia (success_ind) was defined as achievement of bilateral sensory loss to cold at the T6 dermatome or higher, within 10 minutes. Successful maintenance of anesthesia (success_main) was defined by no epidural supplementation within 60 minutes of intrathecal injection. The effective doses for 50% (ED₅₀) and 95% (ED₉₅) of patients were estimated using logistic regression analysis.ResultsThe ED₅₀ and ED₉₅ for success_main were 6.0 mg (95% CI: 4.5 to 7.5 mg) and 12.6 mg (95% CI: 7.9 to 17.2 mg), respectively. The incidence of respiratory discomfort and maternal satisfaction scores did not differ significantly between dose groups. Phenylephrine dose and nausea/vomiting incidence increased with increasing doses of bupivacaine.ConclusionUnder study conditions, our results suggest that 12.6 mg of intrathecal bupivacaine, administered with fentanyl and morphine, is required to achieve adequate intraoperative analgesia without the need for epidural supplemention.     

Comparison of visceral pain incidence during cesarean section performed under spinal or epidural anesthesia

The incidence of visceral pain during cesarean section performed under regional anesthesia was studied in 80 unpremedicated patients. They were divided in two similar groups concerning age, weight and height. Group 1 consisted of 40 patients submitted to cesarean section under spinal anesthesia, while in group 2 (40 patients) epidural anesthesia was used. Surgery was totally painless for all patients of group 1 patients, whereas in group 2 intraoperative analgesia was complete for 11, good in 18 and fair in 10 patients. One patient of group 2 required general anesthesia due to excrutiating pain during exteriorization of uterus despite a seemly adequate lebel of cutaneous analgesia of T₆. The authors conclude that spinal anesthesia favorably compares with epidural anesthesia for cesarean section, because the incidence of visceral pain with the former was nill and because both techniques are equally safe for mothers and neonates.(Weksler N, Ovadia L, Stav A, et al.: Comparison of visceral pain incidence during cesarean section performed under spinal or epidural anesthesia. J Anesth 6: 69–74, 1992)     

Propofol infusion for sedation during spinal anesthesia

Purpose The dose and time course of propofol infusion required to induce rapid sedation without oversedation during spinal anesthesia were investigated. Methods Forty patients scheduled for spinal and epidural anesthesia were studied. After premedication with intramuscular midazolam 0.04 mg·kg⁻¹, an epidural catheter was inserted, followed by spinal anersthesia at L4-L5 with 0.5% hyperbaric tetracaine with epinephrine. The infusion of propofol was started with 10 mg·kg⁻¹·h⁻¹ and was decreased to 5 mg·kg⁻¹·h⁻¹ at spontaneous eye closure. According to the increase or decrease of the sedation level, the infusion does was decreased or increased to half or twice the initial dose, respectively, to keep the Observer's Assessment of Alertness Sedation (OAAS) score at 3 or 4. Results Eye closure was observed at 1.0 ± 0.4 min after the start of insusion. The maintenance insusion dose to keep the OAAS score at 3 or 4 was about 2.5 mg·kg⁻¹·h⁻¹. Conclusion Propofol infusion, starting with 10 mg·kg⁻¹·h⁻¹, decreasing to 5 mg·kg⁻¹·h⁻¹ after 1 minute, and then decreasing to 2.5 mg·kg⁻¹·h⁻¹ after another min induced rapid onset of sedation and kept the OAAS score at 3 or 4 during spinal anesthesia.     

A prospective observational study of the change in regional cerebral oxygen saturation during cesarean delivery in women receiving phenylephrine prophylaxis for spinal hypotension

BackgroundSpinal hypotension causes decreased regional cerebral oxygen saturation (ScO₂) in women undergoing cesarean delivery. In this study we aimed to measure the change in ScO₂ using near infrared spectroscopy in women receiving a prophylactic phenylephrine infusion during cesarean delivery under spinal anesthesia.MethodsThis was a prospective, observational cohort study. Fifty-three women had ScO₂ measurements at the following time points: preoperatively, in the supine position with 30° of left lateral tilt; one and five minutes after spinal anesthesia; at the time of skin incision; immediately after delivery; one minute after commencing the oxytocin infusion; at completion of surgery, and one hour after surgery. Spinal anesthesia and a prophylactic phenylephrine infusion were administered according to a standard treatment protocol. Statistical analysis used the Wilcoxon Signed Rank test with Bonferroni’s correction for multiple comparisons.ResultsBlood pressure was maintained within 20% of baseline throughout surgery. The baseline mean (range) ScO₂ was 61.5% (54.0–66.3%). It decreased significantly at all subsequent measurement points. The maximum decrease was five minutes after spinal anesthesia. Thirty-four (64.2%) of the parturients exhibited ScO₂ values <20% of baseline, or a decrease to below an absolute value of 50%. There was no significant correlation between systolic blood pressure and mean ScO₂.ConclusionSpinal anesthesia with phenylephrine infusion during cesarean delivery is associated with a significant decrease in ScO₂ levels, maximal five minutes later. Further studies are required to establish the clinical significance of this finding.     

Impact of intra-operative dexamethasone after scheduled cesarean delivery: a retrospective study

BackgroundDexamethasone is an effective analgesic and anti-emetic in patients undergoing many surgical procedures but its effects on pain after cesarean delivery are poorly studied. The aim of this study was to evaluate if routine intra-operative administration of dexamethasone improved analgesia and decreased postoperative nausea and vomiting after scheduled cesarean delivery.MethodsElectronic medical record data for scheduled cesarean deliveries performed under neuraxial anesthesia, before and after a practice change that introduced the routine use of intravenous dexamethasone 4 mg, were obtained. Patients were analyzed based on whether they received routine care (n=182) or also received dexamethasone (n=187). The primary outcome was time to first opioid use. Secondary outcomes included postoperative opioid consumption, pain scores, incidence and treatment of postoperative nausea and vomiting, satisfaction and length of stay.ResultsThere was no significant difference between groups in median time to first postoperative opioid administration (15.8 [3.4–48.0] h routine care vs 14.7 [3.2–38.8] h routine care plus dexamethasone, P=0.08). There were no significant differences in any secondary outcomes.ConclusionsThis impact study involving more than 360 patients suggests that routine administration of intra-operative intravenous dexamethasone 4 mg does not provide additional analgesic benefit after scheduled cesarean delivery, in the context of a multimodal postoperative analgesic regimen. Studies are required to determine if a larger dose or repeated administration influence postoperative analgesia or side effects, or whether certain subsets of patients may benefit.     

Ephedrine versus ondansetron in the prevention of hypotension during cesarean delivery: a randomized,double-blind,placebo-controlled trial

BackgroundMaternal hypotension is common after spinal anesthesia for cesarean delivery. We compared the effects of prophylactic ephedrine with ondansetron on post-spinal blood pressure.MethodsOne hundred and sixty-eight term, singleton parturients were enrolled in this prospective, double-blind, placebo-controlled trial. Patients were randomized to receive either prophylactic intravenous ephedrine 10 mg (Group E), ondansetron 8 mg (Group O) or normal saline (Group P) immediately after spinal anesthesia. The primary outcome was maternal blood pressure between spinal block and delivery; secondary outcomes were nausea and vomiting scores, Apgar scores, numbers requiring intraoperative vasoconstrictors and the dose of vasoconstrictors required.ResultsFifty-six patients were recruited to each group, but two in Group P were excluded from the analysis owing to protocol violations. There were no significant differences between the groups in maternal systolic, diastolic or mean arterial pressures, or the proportion of patients experiencing hypotension. The proportion of patients in Group E requiring intraoperative ephedrine or any vasoconstrictor (ephedrine and/or norepinephrine) was significantly lower than that in Group P (P=0.023 and 0.034, respectively). The proportion of patients in Group O requiring intraoperative norepinephrine was significantly lower than that in Group P (P=0.02). There was no difference in the proportions of patients in Groups E and O requiring any vasoconstrictors (P=0.34).ConclusionsThere was no significant difference in maternal blood pressure in women administered prophylactic ephedrine or ondansetron after spinal anesthesia for cesarean delivery compared with placebo. Ephedrine reduced the proportion of patients requiring a rescue vasoconstrictor before delivery.     

Airway management for cesarean delivery performed under general anesthesia

BackgroundWith the increasing popularity of neuraxial anesthesia, there has been a decline in the use of general anesthesia for cesarean delivery. We sought to examine the incidence, outcome and characteristics associated with a failed airway in patients undergoing cesarean delivery under general anesthesia.MethodsA retrospective review of airway management in women undergoing cesarean delivery under general anesthesia over an eight-year period from 2006–2013 at an academic medical center was conducted.ResultsDuring the study period, 10 077 cesarean deliveries were performed. Neuraxial anesthesia was used in 9382 (93%) women while general anesthesia was used in 695 (7%). Emergent cesarean delivery was the most common indication for general anesthesia. Failed intubation was encountered in only three (0.4%) women, who were successfully managed with a laryngeal mask airway. The overall incidence of failed intubation was 1 in 232 (95% CI 1:83 to 1:666) and general anesthesia was continued in all cases. There were no adverse maternal or fetal outcomes directly related to failed intubation.ConclusionAdvances in adjunct airway equipment, availability of an experienced anesthesiologist and simulation-based teaching of failed airway management in obstetrics may have contributed to our improved maternal outcomes in patients undergoing cesarean delivery under general anesthesia.     

Anesthetic management of a parturient with Stiff person syndrome for urgent cesarean delivery

Stiff person syndrome is a rare neurologic disorder with an estimated incidence of 1:1 000 000. The underlying pathophysiology is truncal and proximal limb muscle stiffness resulting from continuous co-contracture of agonist and antagonist muscle groups concomitant with superimposed episodic muscle spasms. Loss of gamma-aminobutyric acid-mediated inhibition creates chronic excitation manifested by tonic agonist-antagonist muscle contraction. To date, only three case reports referred indirectly to the anesthetic management of parturients with Stiff person syndrome. The authors describe their management of a parturient with Stiff person syndrome who underwent urgent cesarean delivery under epidural anesthesia.     

Spinal anesthesia for cesarean section following inadequate labor epidural analgesia: a retrospective audit

BACKGROUND: High blocks have been reported when spinal anesthesia is used for cesarean section following inadequate labor epidural analgesia. We have therefore modified the practice at our institution to minimize this risk and conducted a retrospective observational study of outcome following the change of practice. METHOD: The records of 115 women with inadequate epidural labor analgesia who required cesarean section between July 1998 and January 2002 were studied. No epidural boluses were administered in the 30 min preceding spinal anesthesia and a reduced spinal dose, median (range) 9.38 mg (7.5-11.3 mg) of 0.75% hyperbaric bupivacaine and fentanyl 15 microg (10-25 microg) was used. Patients were left sitting for 2 min and then positioned supine with left uterine displacement and were closely monitored for symptoms or signs that would suggest a high block. RESULTS: No parturient developed a high spinal necessitating intubation, and there was no adverse neonatal outcome. CONCLUSION: These findings do not conclusively establish this method as safe, but should spinal anesthesia for cesarean section following suboptimal labor epidural analgesia be considered, avoiding epidural boluses immediately preceding spinal injection, using a lower spinal dose, and delayed supine positioning following spinal injection may be advisable.     

The effect of baricity of intrathecal bupivacaine for elective cesarean delivery on maternal cardiac output: a randomized study

BackgroundHemodynamic instability during spinal anesthesia for cesarean delivery is associated with adverse maternal and fetal outcomes. Plain and hyperbaric bupivacaine are commonly used for cesarean delivery, however, their distinctive pharmacologic properties may affect maternal hemodynamic profiles differently. The aim of this study was to compare hemodynamic profiles using a suprasternal Doppler cardiac output (CO) monitor in healthy term parturients randomized to receive plain or hyperbaric bupivacaine for cesarean delivery.MethodsOne hundred-and-sixty-eight healthy parturients scheduled for elective cesarean delivery were randomly assigned to receive 10.9 mg of intrathecal 0.5% plain or hyperbaric bupivacaine, both with 0.2 mg morphine. The primary outcome was CO change after spinal anesthesia. Secondary outcomes were the incidence of hypotension, vasopressor use, and conversion to general anesthesia.ResultsThe mean (±SD) CO at baseline, 1 min and 5 min after spinal anesthesia, and after placental delivery was 4.6 ± 1.2, 5.4 ± 1.3, 5.1 ± 1.4, and 6.4 ± 1.7 L/min in the plain bupivacaine, and 4.5 ± 1.1, 5.2 ± 1.3, 4.9 ± 1.3, and 6.2 ± 1.9 L/min in the hyperbaric bupivacaine group. There were no significant differences in CO, mean arterial pressure, or systemic vascular resistance. Incidences of hypotension, vasopressor and supplemental analgesic use, and conversion to general anesthesia, were not different between groups.ConclusionsCardiac output changes after plain or hyperbaric bupivacaine were not different in term parturients undergoing spinal anesthesia for cesarean delivery. Further studies comparing block quality and the rate of conversion to general anesthesia are required.     

Performance of non-invasive stroke volume variation during passive leg raising as a predictor of hypotension following induction of spinal anesthesia for elective cesarean delivery: a single cohort study

BackgroundSpinal anesthesia for cesarean delivery is accompanied by hypotension in up to 70% of cases. To date, there is no gold standard for predicting hypotension after spinal anesthesia for cesarean delivery. The Clearsight™ device is a non-invasive system that uses a digital cuff to calculate stroke volume. We hypothesized that stroke volume variation induced with passive leg raising before spinal anesthesia for elective cesarean delivery could predict the occurrence of hypotension.MethodsWe conducted a prospective observational study, including third trimester parturients undergoing elective cesarean delivery with spinal anesthesia. We analyzed the stroke volume variation performance for predicting hypotension. Stroke volume was collected in the semi-recumbent position (baseline) and during passive leg raising before spinal anesthesia. Systolic arterial blood pressure measurement was followed for 15 min after spinal anesthesia. Hypotension was defined as a ≥20% decrease from the baseline measurement. All parturients received appropriate hypotension prophylaxis.ResultsData from 42 parturients were analyzed. Hypotension occurred in 45%. The area-under-the curve for predicting hypotension using the stroke volume variation was 0.83 (95% CI 0.68 to 0.98; P=0.001). The best cut-off value for predicting hypotension was 7%, having a sensitivity of 87% (95% CI 0.70 to 0.99) and a specificity of 83% (95% CI 0.69 to 0.97).ConclusionIn our study of third trimester parturients undergoing cesarean delivery and receiving appropriate hypotension prophylaxis, a digital non-invasive monitoring device of stroke volume variation analysis was useful for predicting the occurrence of hypotension after spinal anesthesia.     

Repeated simulation-based training for performing general anesthesia for emergency cesarean delivery: long-term retention and recurring mistakes

BackgroundThe percentage of women undergoing cesarean delivery under general anesthesia has significantly decreased, which limits training opportunities for its safe administration. The purpose of this study was to evaluate how effective simulation-based training was in the learning and long-term retention of skills to perform general anesthesia for an emergent cesarean delivery.MethodsDuring an eight-week obstetric anesthesia rotation, 24 residents attended lectures and simulation-based training to perform general anesthesia for emergent cesarean delivery. Performance assessments using a validated weighted scaling system were made during the first (pre-test) and fifth weeks (post-test) of training, and eight months later (post-retention test). Resident’s competency level (weighted score) and errors were assessed at each testing session. Six obstetric anesthesia attending physicians, unfamiliar with the simulation scenario, generated a mean attendings’ performance score. The results were compared.ResultsAt one week of training, residents’ performance was significantly below mean attendings’ performance score (pre-test: 135 ± 22 vs. 159 ± 11, P = 0.013). At five weeks, residents’ performance was similar to mean attendings’ performance score (post-test: 159 ± 21) and remained at that level at eight months (post-retention test: 164 ± 16). Of the important obstetric-specific tasks, left uterine displacement was missed by 46% of residents at eight months.ConclusionFollowing lectures and simulation-enhanced training, anesthesia residents reached and retained for up to eight months a competency level in a simulator comparable to that of obstetric anesthesia attending physicians. Errors in performance and missed tasks may be used to improve residency training and continuing medical education.     

硬膜外阻滞辅以丙泊酚闭环靶控镇静

目的对硬膜外阻滞中以脑电双频指数(BIS)作为反馈的闭环靶控输注丙泊酚镇静的效果和性能进行评价。方法11例ASAⅠ～Ⅱ级择期行下腹部或下肢手术患者，男5例，女6例，年龄28～67岁。硬膜外阻滞期间采用以BIS作为反馈的闭环靶控输注(CLTCI)丙泊酚进行镇静，开始的靶浓度设定为1．5μg／ml，然后每分钟逐步增加或减少0．5μg／ml，直到患者的镇静深度稳定于OAA／S评分3分以下，这时候的BIS值作为反馈变量，通过CLTCI系统自动输注丙泊酚。每5分钟记录血压、心率、BIS和OAA／S评分。记录诱导时间及丙泊酚诱导剂量、丙泊酚总用量、苏醒时间及不良反应，并评价CLTCI系统的性能。结果所有患者镇静期间血液动力学平稳，无严重呼吸抑制。OAA／S评分3分时平均BIS值76．6。CLTCI系统的偏离性1．9％，精确度7．1％，摆动度4．1％。结论在硬膜外麻醉期间以BIS为反馈的闭环靶控输注丙泊酚进行清醒镇静是可行的。该系统性能稳定，有临床推广价值。     

Low-dose intravenous dexmedetomidine reduces shivering following cesarean delivery: a randomized controlled trial

BackgroundIntravenous dexmedetomidine 30 µg reduces shivering after cesarean delivery but can result in sedation and dry mouth. We hypothesized that prophylactic administration of 10 µg of IV dexmedetomidine would reduce the patient-reported severity of shivering after cesarean delivery, without an increased incidence of side effects.MethodsAfter institutional review board approval and informed written consent, women undergoing scheduled cesarean delivery with spinal or combined spinal-epidural anesthesia were randomized to receive either intravenous normal saline or dexmedetomidine 10 µg immediately after delivery. The primary outcome was a patient-rated subjective shivering score using a 10-cm visual analog scale at 30 and 60 min after arrival in the Post-Anesthesia Care Unit. Secondary outcomes included subjective scores for pain, nausea, itching, dry mouth, and sedation, as well as 24-h medication administration and investigator-rated observations of shivering, vomiting, pruritus, and sedation. Repeated measures ANOVA with Tukey-Kramer multiple-comparison test was applied for primary outcomes.ResultsOne hundred patients were enrolled, and 85 completed the study and were included in analysis. The mean ± SD shivering score in the dexmedetomidine group was significantly lower by repeated measures analysis than among controls across the first 60 min (P=0.0002), and individually at both 30 and 60 min (placebo 1.8 ± 2.6 vs. dexmedetomidine 0.6 ± 1.4 at 30 min; 1.2 ± 2.1 vs. 0.3 ± 0.6 at 60 min; both P <0.01). Patient-rated and observer-rated side effects did not significantly differ between groups.ConclusionsProphylactic administration of intravenous dexmedetomidine 10 µg after delivery reduces shivering without notable side effects.     

Determination of ED50 of hydromorphone for postoperative analgesia following cesarean delivery

BackgroundMorphine is the most common opioid injected into the intrathecal space for postoperative analgesia following cesarean delivery, but ongoing medication shortages have resulted in limited availability. One proposed morphine alternative is hydromorphone. Studies investigating its use in post-cesarean analgesia are limited. This study was conducted to determine the median effective dose of intrathecal hydromorphone 12 h postpartum.MethodsTwenty healthy women undergoing elective cesarean delivery were recruited into this study. Hydromorphone doses were determined using the up-down sequential method. The study dose of hydromorphone started at 6 μg and was raised or lowered by 2 μg depending on the 12-h efficacy of the preceding participant’s dose. Pain scores of <3/10 were considered successful and the subsequent patient received a lower dose. Participants received 0.5% bupivacaine 12.5 mg, fentanyl 25 μg, and the study dose of hydromorphone as a single intrathecal injection.ResultsTen of 20 participants reported an effective hydromorphone dosage 12 h post-injection. The median effective hydromorphone dosage was 4.6 μg (95% CI 3.72 to 5.48 μg) based on participants’ reported visual analog pain scores of <3/10. No significant side effects or adverse outcomes were observed.ConclusionIntrathecal hydromorphone may be an effective alternative to morphine for post-cesarean pain management. The amount of intrathecal hydromorphone necessary to provide analgesia at 12 h postoperatively may be significantly lower than doses currently in use. Further research should be performed to identify the optimal dose of intrathecal hydromorphone for post-surgical pain relief.     

Noise levels during cesarean delivery: a prospective observational study

BackgroundExcessive noise has negative implications for both clinicians and patients. Emergency cesarean deliveries require rapid co-ordination and communication, possibly increasing noise pollution. We aimed to determine if noise levels in the Labor and Delivery operating room were higher during emergency cesarean deliveries than during non-emergency cesarean deliveries.MethodsWe conducted a prospective observational study measuring noise levels in Labor and Delivery operating rooms at a single academic medical center. Sound meters placed on anesthesia machines and events charted in the electronic medical record were used to correlate noise levels to clinical activity. Noise levels in all cesarean deliveries were recorded for one year. Deliveries were classified into two groups: non-emergency (routine or urgent) and emergency. We compared noise levels of the groups at eight time points of interest: anesthesia provider enters operating room (T1), induction (T2), five minutes before incision (T3), three minutes before incision (T4), one minute before incision (T5), time of incision (T6), delivery (T7), and five minutes before initiating emergence (T8).ResultsNoise levels were measured for 440 cesarean deliveries. Forty were classified emergency and 400 non-emergency (304 routine, 96 urgent) procedures. Emergency cesarean deliveries were noisier at all eight time points, although the absolute difference in decibels between the two groups was modest. The difference in noise level reached statistical significance at five time points (T1, T2, T5, T6, and T7).ConclusionNoise levels were higher during emergency than during non-emergency cesarean deliveries.     

The impact of gestational age and fetal weight on the risk of failure of spinal anesthesia for cesarean delivery

BackgroundThere are limited data about spinal dosing for cesarean delivery in preterm parturients. We investigated the hypothesis that preterm gestation is associated with an increased incidence of inadequate spinal anesthesia for cesarean delivery compared with term gestation.MethodsWe searched our perioperative database for women who underwent cesarean delivery under spinal or combined spinal-epidural anesthesia with hyperbaric bupivacaine ⩾10.5 mg. The primary outcome was the incidence of inadequate surgical anesthesia needing conversion to general anesthesia or repetition or supplementation of the block. We divided patients into four categories: <28, 28 to <32, 32 to <37 and ⩾37 weeks of gestation. The chi-square test was used to compare failure rates and a multivariable regression analysis was performed to investigate potential confounders of the relationship between gestational age and failure.ResultsA total of 5015 patients (3387 term and 1628 preterm) were included. There were 278 failures (5.5%). The incidence of failure was higher in preterm versus term patients (6.4% vs. 5.1%, P=0.02). Failure rates were 10.8%, 7.7%, 5.3% and 5% for <28, 28 to <32, 32 to <37 and ⩾37 weeks of gestation, respectively. In the multivariable model, low birth weight (P<0.0001), gestational age (P=0.03), ethnicity (P=0.02) and use of combined spinal-epidural anesthesia (P<0.0001) were significantly associated with failure.ConclusionsAt standard spinal doses of hyperbaric bupivacaine used in our practice (⩾10.5 mg), there were higher odds of inadequate surgical anesthesia in preterm parturients. When adjusting for potential confounders, low birth weight was the main factor associated with failure.