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Created page with "When did the ASA make their guideline for fasting? Which studies were cited? Which studies was the ASA (presumably) aware of? Ultimately, the clinical implications of answerin..."
When did the ASA make their guideline for fasting? Which studies were cited? Which studies was the ASA (presumably) aware of? Ultimately, the clinical implications of answering this question would hinge on whether the results would change the ASA guidelines. If new information is unlikely to change guidance, then pursuing this question would be less relevant. Fasting for a few hours post-epidural is very low risk compared to the admittedly rare event of clinically significant aspiration. If you show that epidurals increase gastric emptying that would suggest that they also decrease risk of aspiration. However, if you then let patients with epidurals eat, they have a full stomach and their risk of aspiration is heightened despite any protective effect of an epidural. In other words, the lowest risk category of patients, assuming my hypothesis is true, remains fasted patients with epidurals.
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! Reference !! Population !! Intervention !! Comparator !! Outcome
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| [https://dx.doi.org/10.1097/EJA.0000000000001514 Weiniger et al Eur J of Anaes 2022] || 80 non-fasted pregnant women, age 18+, GA 37+ weeks, singleton, cephalad, dilated <= 5 cm, 63 had empty stomachs and 17 had full stomachs at baseline || Double-blind single center RCT with women randomized to low-dose (50) or high-dose (100) epidural fentanyl. || Stomach antrum cross-sectional area (CSA) was measured with gastric US before and 2 hrs after fentanyl administration || No differences between low-dose and high-dose fentanyl groups.
|-
| [https://dx.doi.org/10.1097/ALN.0000000000004133 Chassard et al Anes 2022] || 40 women || Prospective cohort study. Gastric ultrasound (gUS) was used to verify an empty stomach, then participants ate 125 g of yogurt within 5 min. For the epidural group, the meal was consumed within one hour of epidural placement. || 10 parturients with labor epidural were compared with 10 pregnant women at term, 10 non-pregnant women, and 10 parturiants with no labor epidural. Serial gUS was performed at 15, 60, 90, and 120 minutes after a light meal and fraction of gastric emptying was calculated as [Area_Antral_90 / Area_Antral_15 - 1]*100. || Gastric emptying fraction (higher is better) was 52% (non-pregnant), 45% (pregnant), 7% (parturiants w/o epidural), and 31% (parturiants w/ epidural). Parturiants had delayed gastric emptying compared to non-parturiants, and epidural analgesia actually sped up gastric emptying.
|-
| [https://dx.doi.org/10.1093/bja/aet435 Bonnet et al BJA 2014] || 60 spontaneously laboring parturients with ropivacaine/sufentanil PCEA analgesia || CSA measured with binary outcome of "full" or "not full" based on cutoff CSA value of >320 determined in small pilot study of 6 pregnant women. || gUS compared CSA when the anesthesiologist was called for epidural placement (beginning of labor) and at full cervical dilation. || 50% had full stomachs at epidural placement compared to 13% at full cervical dilation.
|-
| [https://dx.doi.org/10.1007/s00540-008-0692-5 Inada et al J of Anes 2009] || 16 ASA 1-2 term parturients undergoing elective cesarean delivery || CSE w/ 10 mg Bupivacaine and 10 mcg Fentanyl || Four channel electrogastrography was performed for 10 min at 5 interval time points. || Frequency of gastric contractions increased after spinal anesthetic, during the surgery, and returned to the (presumed) non-pregnant normal values by POD7.
|-
| [https://ovidsp.dc2.ovid.com/ovid-new-b/ovidweb.cgi?&S=EGCFFPEMIIEBOLIHJPKJIFDGCBGDAA00&PDFLink=B%7cS.sh.20%7c9&WebLinkReturn=Titles%3dS.sh.20%7c9%7c50%26FORMAT%3dtitle%26FIELDS%3dTITLES&Counter5=SS_as_pdf%7c17717235%7cmedall%7cmedline%7cmed6 Avram et al Anes and Analg 2007] || 10 obese (pre-pregnancy BMI > 35), pregnant, term, non-laboring, fasted women || gUS measurement of CSA and acetaminophen absorption test was used to measure gastric emptying || 1.5g APAP was taken with 50 or 300 ml of water (cross-over design randomly assigned and separated by 2+ days) before measurement/calculation of CSA, gastric emptying half-time, APAP AUC, and C(max) T(max) for APAP concentration. || There were no differences in CSA, gastric 1/2 time, AUC, C(max), or T(max) between the 50 and 300 ml tests.
|-
| [https://pubmed.ncbi.nlm.nih.gov/10455830/ O'Sullivan et al Anes 1999] || 94 women in labor || Women were randomised to light diet or water only || CSA and metabolic profiles were compared, as well as length of labor and labor outcome || Blood glucose and insulin were higher and plasma betahydroxybutyrate and non-esterified fatty acids were lower in the diet group. There were no differences in labor course, labor outcomes (e.g. mode of delivery, umbilical artery/vein samples, and APGAR scores). CSA was higher in the diet group as was emesis volume.
|-
| [https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2044.1997.238-az0373.x?sid=Ovid%3Amedline Reynolds et al Anes 1997] || 56 women in labor, >36 weeks gestation, singleton, cephalad, no systemic opioids || Women had epidurals placed and were given 1.5g of paracetamol, then had serum levels measured at 0, 15, 30, 45, 60, and 90 minute timepoints. || Women were randomly assigned to either 0.125% bupivacaine solution or 0.0625% bupivacaine with 2.5 mcg/ml fentanyl, with continuous infusion rate titrated to effect. Rescue boluses of 5 ml 0.25% bupivacaine were given as needed. In study A, 28 women received paracetamol after 30 ml (75 mcg of fentanyl), while in study B it was after 40-50 ml (100-125 mcg of fentanyl). || No significant differences in AUC, peak concentration, or time to peak concentration in study A. In study B, the time to max concentration was delayed in the fentanyl group.
|-
| [https://ovidsp.dc2.ovid.com/ovid-new-b/ovidweb.cgi?WebLinkFrameset=1&S=EGLNFPLEIIEBMLKBIPKJOFPFCBGDAA00&returnUrl=ovidweb.cgi%3f%26Titles%3dS.sh.20%257c13%257c50%26FORMAT%3dtitle%26FIELDS%3dTITLES%26S%3dEGLNFPLEIIEBMLKBIPKJOFPFCBGDAA00&fromjumpstart=0&directlink=https%3a%2f%2fovidsp.dc2.ovid.com%2fovftpdfs%2fFPEBIPPFOFKBII00%2ffs047%2fovft%2flive%2fgv024%2f00000539%2f00000539-199710000-00022.pdf&filename=A+Comparison+of+the+Effect+of+Intrathecal+and+Extradural+Fentanyl+on+Gastric+Emptying+in+Laboring+Women.&navigation_links=NavLinks.S.sh.20.13&PDFIdLinkField=%2ffs047%2fovft%2flive%2fgv024%2f00000539%2f00000539-199710000-00022&link_from=S.sh.20%7c13&pdf_key=B&pdf_index=S.sh.20&D=medall Mirakhur et al Anes and Analg 1997] || 105 parturiants || APAP absorption assay was done in women getting neuraxial labor analgesia || Neuraxial analgesia was administered with bupivacaine and 25 mcg intrathecal fentanyl (S), 50 mcg epidural fentanyl (E), or no opioid (C). APAP CMax, TMax, and AUC were measured at 60 and 120 min || Median (range) TMax values were 120 (15-180), 82.5 (15-180), and 90 (15-180) min in Groups S, E, and C, respectively (P < 0.05). Mean ± SD CMax was 13.4 ± 8.82, 17.9 ± 8.06, and 15.0 ± 6.22 µg/mL in Groups S, E, and C, respectively (P < 0.05). Mean ± SD AUC90 and AUC120 were also significantly smaller in Group S than in the other two groups (430 ± 616, 736 ± 504, and 672 ± 453; and 649 ± 592, 1063 ± 627, and 1053 ± 616 µg/ml/min in Groups S, E, and C, respectively).
|}
{| class="wikitable"
|-
! Reference !! Population !! Intervention !! Comparator !! Outcome
|-
| [https://dx.doi.org/10.1097/EJA.0000000000001514 Weiniger et al Eur J of Anaes 2022] || 80 non-fasted pregnant women, age 18+, GA 37+ weeks, singleton, cephalad, dilated <= 5 cm, 63 had empty stomachs and 17 had full stomachs at baseline || Double-blind single center RCT with women randomized to low-dose (50) or high-dose (100) epidural fentanyl. || Stomach antrum cross-sectional area (CSA) was measured with gastric US before and 2 hrs after fentanyl administration || No differences between low-dose and high-dose fentanyl groups.
|-
| [https://dx.doi.org/10.1097/ALN.0000000000004133 Chassard et al Anes 2022] || 40 women || Prospective cohort study. Gastric ultrasound (gUS) was used to verify an empty stomach, then participants ate 125 g of yogurt within 5 min. For the epidural group, the meal was consumed within one hour of epidural placement. || 10 parturients with labor epidural were compared with 10 pregnant women at term, 10 non-pregnant women, and 10 parturiants with no labor epidural. Serial gUS was performed at 15, 60, 90, and 120 minutes after a light meal and fraction of gastric emptying was calculated as [Area_Antral_90 / Area_Antral_15 - 1]*100. || Gastric emptying fraction (higher is better) was 52% (non-pregnant), 45% (pregnant), 7% (parturiants w/o epidural), and 31% (parturiants w/ epidural). Parturiants had delayed gastric emptying compared to non-parturiants, and epidural analgesia actually sped up gastric emptying.
|-
| [https://dx.doi.org/10.1093/bja/aet435 Bonnet et al BJA 2014] || 60 spontaneously laboring parturients with ropivacaine/sufentanil PCEA analgesia || CSA measured with binary outcome of "full" or "not full" based on cutoff CSA value of >320 determined in small pilot study of 6 pregnant women. || gUS compared CSA when the anesthesiologist was called for epidural placement (beginning of labor) and at full cervical dilation. || 50% had full stomachs at epidural placement compared to 13% at full cervical dilation.
|-
| [https://dx.doi.org/10.1007/s00540-008-0692-5 Inada et al J of Anes 2009] || 16 ASA 1-2 term parturients undergoing elective cesarean delivery || CSE w/ 10 mg Bupivacaine and 10 mcg Fentanyl || Four channel electrogastrography was performed for 10 min at 5 interval time points. || Frequency of gastric contractions increased after spinal anesthetic, during the surgery, and returned to the (presumed) non-pregnant normal values by POD7.
|-
| [https://ovidsp.dc2.ovid.com/ovid-new-b/ovidweb.cgi?&S=EGCFFPEMIIEBOLIHJPKJIFDGCBGDAA00&PDFLink=B%7cS.sh.20%7c9&WebLinkReturn=Titles%3dS.sh.20%7c9%7c50%26FORMAT%3dtitle%26FIELDS%3dTITLES&Counter5=SS_as_pdf%7c17717235%7cmedall%7cmedline%7cmed6 Avram et al Anes and Analg 2007] || 10 obese (pre-pregnancy BMI > 35), pregnant, term, non-laboring, fasted women || gUS measurement of CSA and acetaminophen absorption test was used to measure gastric emptying || 1.5g APAP was taken with 50 or 300 ml of water (cross-over design randomly assigned and separated by 2+ days) before measurement/calculation of CSA, gastric emptying half-time, APAP AUC, and C(max) T(max) for APAP concentration. || There were no differences in CSA, gastric 1/2 time, AUC, C(max), or T(max) between the 50 and 300 ml tests.
|-
| [https://pubmed.ncbi.nlm.nih.gov/10455830/ O'Sullivan et al Anes 1999] || 94 women in labor || Women were randomised to light diet or water only || CSA and metabolic profiles were compared, as well as length of labor and labor outcome || Blood glucose and insulin were higher and plasma betahydroxybutyrate and non-esterified fatty acids were lower in the diet group. There were no differences in labor course, labor outcomes (e.g. mode of delivery, umbilical artery/vein samples, and APGAR scores). CSA was higher in the diet group as was emesis volume.
|-
| [https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2044.1997.238-az0373.x?sid=Ovid%3Amedline Reynolds et al Anes 1997] || 56 women in labor, >36 weeks gestation, singleton, cephalad, no systemic opioids || Women had epidurals placed and were given 1.5g of paracetamol, then had serum levels measured at 0, 15, 30, 45, 60, and 90 minute timepoints. || Women were randomly assigned to either 0.125% bupivacaine solution or 0.0625% bupivacaine with 2.5 mcg/ml fentanyl, with continuous infusion rate titrated to effect. Rescue boluses of 5 ml 0.25% bupivacaine were given as needed. In study A, 28 women received paracetamol after 30 ml (75 mcg of fentanyl), while in study B it was after 40-50 ml (100-125 mcg of fentanyl). || No significant differences in AUC, peak concentration, or time to peak concentration in study A. In study B, the time to max concentration was delayed in the fentanyl group.
|-
| [https://ovidsp.dc2.ovid.com/ovid-new-b/ovidweb.cgi?WebLinkFrameset=1&S=EGLNFPLEIIEBMLKBIPKJOFPFCBGDAA00&returnUrl=ovidweb.cgi%3f%26Titles%3dS.sh.20%257c13%257c50%26FORMAT%3dtitle%26FIELDS%3dTITLES%26S%3dEGLNFPLEIIEBMLKBIPKJOFPFCBGDAA00&fromjumpstart=0&directlink=https%3a%2f%2fovidsp.dc2.ovid.com%2fovftpdfs%2fFPEBIPPFOFKBII00%2ffs047%2fovft%2flive%2fgv024%2f00000539%2f00000539-199710000-00022.pdf&filename=A+Comparison+of+the+Effect+of+Intrathecal+and+Extradural+Fentanyl+on+Gastric+Emptying+in+Laboring+Women.&navigation_links=NavLinks.S.sh.20.13&PDFIdLinkField=%2ffs047%2fovft%2flive%2fgv024%2f00000539%2f00000539-199710000-00022&link_from=S.sh.20%7c13&pdf_key=B&pdf_index=S.sh.20&D=medall Mirakhur et al Anes and Analg 1997] || 105 parturiants || APAP absorption assay was done in women getting neuraxial labor analgesia || Neuraxial analgesia was administered with bupivacaine and 25 mcg intrathecal fentanyl (S), 50 mcg epidural fentanyl (E), or no opioid (C). APAP CMax, TMax, and AUC were measured at 60 and 120 min || Median (range) TMax values were 120 (15-180), 82.5 (15-180), and 90 (15-180) min in Groups S, E, and C, respectively (P < 0.05). Mean ± SD CMax was 13.4 ± 8.82, 17.9 ± 8.06, and 15.0 ± 6.22 µg/mL in Groups S, E, and C, respectively (P < 0.05). Mean ± SD AUC90 and AUC120 were also significantly smaller in Group S than in the other two groups (430 ± 616, 736 ± 504, and 672 ± 453; and 649 ± 592, 1063 ± 627, and 1053 ± 616 µg/ml/min in Groups S, E, and C, respectively).
|}