The persisting analgesic effect of low-dose intravenous ketamine after spinal anaesthesia for Caesarean section

Effect of Intravenous Ketamine on Hypocranial Pressure Symptoms in Patients with Spinal Anesthetic Cesarean Sections: A Systematic Review and Meta-Analysis

Background: Pregnant women are more likely to suffer post-puncture symptoms such as headaches and nausea due to the outflow of cerebrospinal fluid after spinal anesthesia. Because ketamine has the effect of raising intracranial pressure, it may be able to improve the symptoms of perioperative hypocranial pressure and effectively prevent the occurrence of hypocranial pressure-related side effects. Method: Keywords such as ketamine, cesarean section, and spinal anesthesia were searched in databases including Medline, Embase, Web of Science, and Cochrane from 1976 to 2021. Thirteen randomized controlled trials were selected for the meta-analysis. Results: A total of 12 randomized trials involving 2099 participants fulfilled the inclusion criteria. There was no significant association between ketamine and the risk of headaches compared to the placebo (RR = 1.12; 95% CI: 0.53, 2.35; p = 0.77; I² = 62%). There was no significant association between ketamine and nausea compared to the placebo (RR = 0.66; 95% CI: 0.40, 1.09; p = 0.10; I² = 57%). No significant associations between ketamine or the placebo and vomiting were found (RR = 0.94; 95% CI: 0.53, 1.67; p = 0.83; I² = 72%). Conclusion: Intravenous ketamine does not improve the symptoms caused by low intracranial pressure after spinal anesthesia in patients undergoing cesarean section.

The Effect of Intravenous Ketamine After Spinal Anesthesia on the Duration of Postoperative Analgesia and Analgesic Requirement

Background

One of the most unpleasant aspects of surgery for a patient is postoperative discomfort. To treat the pain prophylactically, deliberate action should be taken. Exogenous opioids, such as morphine or fentanyl, have been used as the cornerstone of treatment to date. Opioid use is frequently linked to negative consequences. Ketamine is by far the most adaptable anesthetic medication accessible, possibly in all of medicine. Ketamine’s principal analgesic impact is because of its antagonism to N-methyl-D-aspartate receptors (NMDA) receptors. Ketamine affects pain processing in the central nervous system in this way. Ketamine has proven to be an effective antihyperalgesic, preventing opioid-induced hyperalgesia. Therefore, we investigated the impact of ketamine following spinal anesthesia on the duration of postoperative analgesia and the need for analgesics.

Methods

This was a prospective, randomized, double-blinded study done over a period of two years. A total of 60 patients undergoing elective surgeries under spinal anesthesia were randomized into two groups. After 10 min of spinal anesthesia and achieving the required level of sensory and motor blockade, both groups were given Inj. Midazolam 1 mg intravenously, followed by Inj. Ketamine 0.25 mg/kg, volume made up to 10 mL with normal saline, given intravenously in Group K and Inj. Normal Saline 10 mL was given intravenously in Group N. Hemodynamic monitoring was done intraoperatively, and the postoperative visual analog score (VAS), sedation score, the mean time for the first rescue analgesia, and the total dose of postoperative analgesic required in 24 h were tabulated.

Results

There was no statistical difference between the two groups in terms of age, weight, ASA grade, and duration of surgery. In Group K, the VAS scores were significantly lower and patients were comfortable when compared to Group N ( P-value <.01). The mean time to first rescue analgesia was longer in Group K (6.4 ± 1.69 h) when compared to Group N (2.9 ± 1.01 h), and the total dose of postoperative analgesia (Tramadol) required in 24 h was also significantly less in Group K (143.33 ± 56.83 mg) when compared to Group N (236 ± 49.01 mg). Changes in hemodynamic parameters (heart rate and mean arterial pressure (MAP) were statistically and clinically not significant in both the intraoperative and postoperative periods in both the groups.

Conclusion

Patients in Group K were more comfortable, had a longer duration of postoperative analgesia, and required less dose of rescue analgesia in the postoperative period. Ketamine is a safe drug that is readily available, and it decreases the use of opioids and opioid-related side effects. Therefore, ketamine can serve effectively as an adjunctive analgesic drug.

Effect of low-dose intravenous ketamine on postoperative pain following cesarean section under spinal anesthesia: A prospective cohort study, Ethiopia

Background

Following cesarean delivery, mothers experience moderate to severe pain since postoperative analgesia of spinal anesthesia is limited by duration of local anesthetic agents used. Analgesic effect of local anesthetic agents could be extended and supported by adding either intravenous or intrathecal adjuvants. The primary outcome of this study is to assess effect of low-dose intravenous ketamine on postoperative pain following cesarean section under spinal anesthesia.

Materials and methods

This prospective observational cohort study recruits 60 parturients who underwent elective cesarean delivery under spinal anesthesia. Those parturients who received intravenous ketamine 0.25 mg/kg following spinal anesthesia were considered as exposed group/ketamine group. The Non-exposed group was those parturients who didn't receive intravenous ketamine following spinal anesthesia. Numerical rating scale pain score, time to request first analgesia and total analgesia consumptions were recorded starting from 1st hour to 24 h after the end of surgery.

Results

The median and Inter quartile range (IQR) for postoperative numerical rating scale pain score was significantly higher in non-exposed group compered to ketamine group at 1st and 2nd hour after operation (P-value<0.05). Time to request first analgesia was significantly longer in ketamine group [192.5(140–210) minutes] compared to non-Exposed group [146(130–160) minutes] with P-value < 0.001. Tramadol consumption within 24 h postoperatively were significantly lower in ketamine group compared to non-exposed group (P-value < 0.001).

Conclusion

Low dose intravenous ketamine before skin incision was extended postoperative first analgesia request time by average of 45.5 min and decrease total analgesia consumption in 24 h.

•

Ketamine group recorded significantly lower median pain NRS score at 1st and 2nd hour after operation.

•

Total analgesic consumption within 24 h was less in ketamine group.

•

First analgesia requestion time were longer in ketamine compared to non-exposed group postoperatively.

Optimum dose of spinal ropivacaine with or without single intravenous bolus of S-ketamine during elective cesarean delivery: a randomized, double-blind, sequential dose-finding study

Background

Maternal hypotension after spinal anaesthesia occurs at a high rate during caesarean delivery and can lead to adverse maternal or foetal outcomes. The aim of this study was to determine the optimal dose of spinal ropivacaine for caesarean section with or without intravenous single bolus of S-ketamine and to observe the rates of hypotension associated with both methods.

Methods

Eighty women undergoing elective caesarean delivery were randomly allocated into either a ropivacaine only or ropivacaine with intravenous S-ketamine group. If the upper sensory level of the patient reached T6 and the visual analogue scale (VAS) scores remained below 3 points before delivery, the next patient had a 1/9th chance of receiving a lower dose or an 8/9th chance of receiving the same dose as the previous patient. If the patient had VAS scores of more than 2 points or needed an extra epidural rescue bolus before delivery, a higher dose was used for the next patient. The primary outcome was the successful use of spinal ropivacaine to maintain patient VAS score of < 3 points before delivery and the incidence of post-spinal hypotension in both groups. Secondary outcomes included the rates of hypotension-related symptoms and interventions, upper sensory level of anaesthesia, level of sedation, neonatal outcomes, Edinburgh Postnatal Depression Scale scores at admission and discharge, and post-operative analgesic effect. The 90% effective dose (ED90) and 95% confidence interval (95% CI) were estimated by isotonic regression.

Results

The estimated ED90 of ropivacaine was 11.8 mg (95% CI: 11.7–12.7) with and 14.7 mg (95% CI: 14.6–16.0) without intravenous S-ketamine, using biased coin up-down sequential dose-finding method. The rates of hypotension and associated symptoms were significantly lower in S-ketamine group than in the ropivacaine only group.

Conclusions

A spinal dose of ropivacaine 12 mg with a single intravenous 0.15 mg/kg bolus dose of S-ketamine may significantly reduce the risk of hypotension and induce sedation before delivery. This method may be used with appropriate caution for women undergoing elective caesarean delivery and at a high risk of hypotension or experiencing extreme nervousness.

Trial registration

http://www.chictr.org.cn (ChiCTR2000040375; 28/11/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04229-y.

The Current Consideration, Approach, and Management in Postcesarean Delivery Pain Control: A Narrative Review

Optimal postoperative analgesia has a significant impact on patient recovery and outcomes after cesarean delivery. Multimodal analgesia is the core principle for cesarean delivery and pain management. For a standard analgesic regimen, the use of long-acting neuraxial opioids (e.g., morphine) and adjunct drugs, such as scheduled acetaminophen and nonsteroidal anti-inflammatory drugs, is recommended unless contraindicated. Oral or intravenous opioids should be reserved for breakthrough pain. In addition to the aforementioned use of multimodal analgesia, preoperative evaluation is critical to individualize the analgesic regimen according to the patient requirements. Risk factors for severe postoperative pain or analgesia-related adverse effects will require modifications to the standard analgesic regimen (e.g., the use of ketamine, gabapentinoids, or regional anesthetic techniques). Further investigation is required to determine analgesic drugs or dose alterations based on preoperative predictions for patients at risk of severe pain. Outcomes beyond pain and analgesic use, such as functional recovery, should be determined to evaluate analgesic treatment protocols.

Intraoperative ketamine for reduction in postpartum depressive symptoms after cesarean delivery: A double-blind, randomized clinical trial

BACKGROUND

Postpartum depression (PPD) is a common mental disease happens in perinatal period. Ketamine as an anesthesia and analgesia drug has been used for a long time. In recent years, ketamine is proved to have an antidepression effect with a single administration. We hypothesized that intraoperative ketamine can reduce postpartum depressive symptoms after cesarean delivery.

METHODS

In a randomized, double-blind, placebo-controlled study trail, healthy women scheduled for cesarean delivery were randomly assigned to receive intravenous ketamine (0.25 mg/kg diluted to 5 ml with 0.9% saline) or placebo (5 ml of 0.9% saline) within 5 min following clamping of the neonatal umbilical cord. The primary outcome was the degree of postpartum depressive symptoms, which was evaluated by Edinburgh Postnatal Depression Scale (EPDS, a threshold of 9/10 was used) at 1 week, 2 weeks, and 1 month after delivery. The secondary outcome was the numerical rating scale (NRS) score of pain at 2 days postpartum. This trail is registered in the Chinese Clinical Trial Registry, number ChiCTR1900022464.

RESULTS

Between 26 January 2019 and 15 July 2019, 502 subjects were screened and 330 were randomly allocated: 165 (50%) to the ketamine group and 165 (50%) to the placebo group. There were significant differences in the degree of postpartum depressive symptoms between subjects in the ketamine group and the placebo group at 1 week postpartum (13.1% vs. 22.6%, respectively; p = .029). However, no difference was found between subjects in the two groups at 2 weeks (11.8% vs. 16.8%, respectively; p = .209) and 1 month postpartum (10.5% vs. 14.2%, respectively; p = .319). The NRS score of wound pain (3.0 ± 0.9 vs. 4.0 ± 1.0, respectively; p < .001) and uterine contraction pain (3.0 ± 0.9 vs. 4.1 ± 0.9, respectively; p < .001) was lower in the ketamine group at 2 days postpartum compared with placebo group. The prevalence of headache, hallucination, and dizziness was higher in the ketamine group than the placebo group during the operation.

CONCLUSIONS

Operative intravenous ketamine (0.25 mg/kg) can reduce the postpartum depressive symptoms for 1 week. The long-time effect is remained to be seen.

Effect of Low-Dose Intravenous Ketamine on Prevention of Headache After Spinal Anesthesia in Patients Undergoing Elective Cesarean Section: A Double-Blind Clinical Trial Study

Background

Spinal anesthesia is the most commonly used method for elective cesarean section, which is a popular technique due to its simplicity, reliability, and speed to achieve adequate anesthesia. Headache following dura perforation is the most important delayed complication following spinal and epidural anesthesia.

Objectives

To evaluate the impact of low-dose intravenous ketamine in patients undergoing cesarean section under spinal anesthesia on the prevention of dura perforation headache (PDPH).

Methods

This clinical trial study was performed on 64 pregnant women undergoing cesarean section at Vali-e-Asr Hospital. The patients were divided into two groups. In the case group, 0.15 mg/kg body weight ketamine was injected intravenously and in the control group, normal saline was used as the placebo. The incidence of headache and its severity at one, 4, 12, and 24 hours postoperatively, nausea and its severity were also measured and compared. Independent t-test, Mann-Whitney U and chi-square tests were used. A P value < 0.05 was considered statistically significant.

Results

The data revealed that low dose intravenous ketamine significantly decreased patients’ headaches (P = 0.001), the sensation of pruritus (P = 0.009), and the need for analgesic (P = 0.001). Furthermore, the sensation of postoperative nausea was less in the case group. The patients in the case and control groups had no significant difference in terms of hypertension or bradycardia (P = 0.717 and 0.939, respectively).

Conclusions

The injection of ketamine as a premedication in the cesarean section can reduce the severity of postoperative headache in mothers. Therefore, it is recommended to use ketamine as an anti-headache drug in pregnant women.

Post-caesarean delivery analgesia in resource-limited settings: a narrative review

Post-caesarean pain is an important and often neglected outcome. It causes suffering, affects breastfeeding and is associated with postpartum depression and the development of chronic pain syndromes. Pain control is often difficult even in resource-rich environments; it is likely far worse in resource-limited settings, where emphasis is on reducing the high maternal mortality rate. Lack of adequate staffing, education, and postoperative monitoring severely limit the options in resource-limited settings. Resource-limited settings are further compromised by limited access to essential analgesic drugs and equipment for their administration. Solutions using affordable and accessible medications as part of a multimodal analgesic strategy are possible, supplemented by education and training programmes. More research is required, both to establish current practice and to test methods for improving maternal pain control. While government involvement is necessary to improve infrastructure and resources in individual countries, other solutions should also be sought, empowering local institutions and harnessing individual cultural characteristics.

Influence of Difference in Timing of Perioperative Administration of Low-dose Ketamine on Postoperative Analgesia

Background:

Preemptive analgesia is a part of multimodal regime for effective postoperative analgesia. Ketamine is said to possess preemptive effects, which has been simultaneously refuted by other studies. Hence, we designed this randomized, double-blinded trial to establish the influence of timing of perioperative ketamine administration for superior postoperative analgesia.

Methods:

Ninety patients undergoing infraumbilical surgeries under spinal anesthesia were randomized to receive ketamine either preincision (Group KI), preincision and during skin closure (Group KII), or only during skin closure (Group KIII). Outcomes studied were postoperative pain, sedation, and incidence of side effects.

Results:

Analysis of variance statistics for postoperative visual analog scales (VAS) for pain showed no significant difference in three groups. However, there was a significant difference between Groups KII and KIII in the immediate postoperative period (95% confidence interval [CI] of mean VAS for Group KI = 0.9249–1.4889; 95% CI for Group KII = 1.4406–1.8260; P = 0.043). Sedation scores in the immediate, 4 h and 8 h postoperative showed a significant difference between Group KI and Group KII (P = 0.007, 0.008, 0.001, respectively) and between Group KI and KIII (KI: KIII - P = 0.0008, 0.0006, 0.02, respectively). Although the incidence of psychotomimetic effect was more in Groups KIII, it was not statistically significant.

Conclusion:

Ketamine possesses postoperative analgesic effects in the immediate postoperative period only when its preemptive administration is supplemented with repeat administration during closure. Incidences of side effects were comparable in all groups.

Optimal Pain Management After Cesarean Delivery

Cesarean delivery rates are increasing worldwide, and effective postoperative pain management is a key priority of women undergoing cesarean delivery. Inadequate pain management in the acute postoperative period is associated with persistent pain, greater opioid use, delayed functional recovery, and increased postpartum depression. In addition to pain relief, optimal management of patients after cesarean delivery should address the goals of unrestricted maternal mobility, minimal maternal and neonatal side effects, rapid recovery to baseline functionality, and early discharge home. Multimodal analgesia should include neuraxial morphine in conjunction with nonopioid adjuncts, with additional oral or intravenous opioids reserved for severe breakthrough pain.

Perioperative low-dose ketamine improves postoperative analgesia following Cesarean delivery with general anesthesia

OBJECTIVE

In this study, the effect of perioperative uses of low dose ketamine on post-operative wound pain and analgesic consumption in patients undergoing elective Cesarean section was evaluated.

METHODS

In randomized, double blind clinical trial, 52 women with American Society of Anesthesiologists (ASA) class I-II identification undergoing elective Cesarean section in general anesthesia were enrolled. In the ketamine group (group K), a ketamine bolus of 0.5 mg kg(-1) IV was administered at the time of induction of general anesthesia. After induction, a ketamine infusion of 0.25 mg kg(-1) h(-1) was started and discontinued at the end of surgery. Patients allocated to the control group (group C) were given identical volumes of saline. The cumulative dose of morphine consumption after surgery was measured as the primary outcome of this study. Secondary outcomes were pain control assessed by numeric rating scale (NRS) and need for rescue analgesia and incidence of side effects.

RESULTS

The mean 24-h morphine consumption was lower in group K (p = 0,001). At 15 min postoperatively, NRS values were lower in group K than group C (p = 0,001). There was no difference among groups regarding the need for supplemental analgesia (rescue diclofenac doses) (p > 0.05).

CONCLUSIONS

Perioperative uses of low dose ketamine decreased post-operative opioid requirements, which was observed long after the normal expected duration of ketamine.

Intravenous ketamine during spinal and general anaesthesia for caesarean section: systematic review and meta-analysis

BACKGROUND

Intravenous ketamine has been used during general and regional anaesthesia for caesarean section. No systematic review and meta-analysis on the desired effects and adverse effects of ketamine administration during caesarean section have yet been performed.

METHODS

After a systematic literature search a meta-analysis was conducted with the random effects model. Weighted mean difference (WMD) or risk ratio and 95% confidence intervals (CIs) were computed.

RESULTS

Twelve randomised controlled double-blind trials comprising 953 patients were included: seven studies reported on spinal anaesthesia and five on general anaesthesia. Significant differences in the aforementioned outcome variables were found only in the spinal anaesthesia studies. In the spinal anaesthesia studies the time to the first analgesic request was significantly longer in ketamine-treated women, the WMD was 49.36 min (95% CI 43.31-55.41); visual analogue scale pain scores at rest 2 h after surgery were significantly lower. No differences were observed for maternal nausea, vomiting, pruritus, and psychomimetic effects. Only few data were found for neonatal outcomes.

CONCLUSIONS

We conclude that ketamine enhances post-operative analgesia after caesarean section under spinal anaesthesia. There is a paucity of data for several maternal adverse effects as well as for neonatal well-being. Further studies are needed for general anaesthesia.

The effect of low-dose intravenous ketamine on postoperative pain following cesarean section with spinal anesthesia: a randomized clinical trial

OBJECTIVES

Low-dose ketamine has been considered a good substitute for opioids for controlling postoperative pain. The purpose of this study was to determine the effect of low-dose intravenous ketamine following cesarean section with spinal anesthesia on postoperative pain and its potential complications.

METHODS

One hundred and sixty pregnant women volunteered to participate in this randomized controlled trial. Participants were randomly divided into two groups (n=80 for each group). Five minutes after delivery, the experimental group received 0.25mg/kg ketamine while the control group received the same amount of normal saline.

RESULTS

There was a significant difference between the two groups in the severity of pain at one, two, six, and 12 hours following surgery. Postoperative pain was significantly less severe in the experimental group. Compared to the control group, the experimental group felt pain less frequently and therefore asked for analgesics less often. On average, the number of doses of analgesics used for the participants in the experimental group was significantly less than the number of doses used for the control group. Analgesic side effects (including nausea, itching, and headache) were not significantly different between the two groups. However, vomiting was significantly more prevalent in the control group and hallucination was more common in the experimental group.

CONCLUSION

We conclude that administration of low doses of ketamine after spinal anesthesia reduces the need for analgesics and has fewer side effects than using opioids. Further studies are required to determine the proper dose of ketamine which offers maximum analgesic effect. Furthermore, administration of low-dose ketamine in combination with other medications in order to minimize its side effects warrants further investigation.

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naïve patients undergoing colon surgery when nitrous oxide is used - a randomized study

BACKGROUND

The analgesic properties of ketamine are associated with its non-competitive antagonism of the N-methyl-D-aspartate receptor; these receptors exhibit an excitatory function on pain transmission and this binding seems to inhibit or reverse the central sensitization of pain. In the literature, the value of this anesthetic for preemptive analgesia in the control of postoperative pain is uncertain. The objective of this study was to ascertain whether preoperative low-dose ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery.

METHODS

In a double-blind, randomized trial, 48 patients were studied. Patients in the ketamine group received 0.5 mg/kg intravenous ketamine before surgical incision, while the control group received normal saline. The postoperative analgesia was achieved with a continuous infusion of morphine at 0.015 mg∙kg-¹∙h-¹ with the possibility of 0.02 mg/kg bolus every 10 min. Pain was assessed using the Visual Analog Scale (VAS), morphine consumption, and hemodynamic parameters at 0, 1, 2, 4, 8, 12, 16, and 24 hours postoperatively. We quantified times to rescue analgesic (Paracetamol), adverse effects and patient satisfaction.

RESULTS

No significant differences were observed in VAS scores between groups (P>0.05), except at 4 hours postoperatively (P=0.040). There were no differences in cumulative consumption of morphine at any time point (P>0.05). We found no significant differences in incremental postoperative doses of morphine consumption in bolus, except at 12 h (P =0.013) and 24 h (P =0.002). The time to first required rescue analgesia was 70 ± 15.491 min in the ketamine group and 44 ± 19.494 min in the control (P>0.05). There were no differences in hemodynamic parameters or patient satisfaction (P>0.05).

CONCLUSIONS

Preoperative low-dose-ketamine did not show a preemptive analgesic effect or efficacy as an adjuvant for decreasing opioid requirements for postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

The comparison of the effects of intravenous ketamine or dexmedetomidine infusion on spinal block with bupivacaine

Background

Ketamine and dexmedetomidine are commonly used for sedation and analgesia in patients. We tried to compare the effects of intravenous ketamine and dexmedetomidine infusion on spinal block with bupivacaine.

Methods

Ninety American Society of Anesthesiologists physical status class I or II patients, who were scheduled to spinal anesthesia were randomly assigned to one of three groups (n = 30). Normal saline 10 ml, 5 ml/hr (loading dose for 10 minutes, infusion) (Group NS), dexmedetomidine 1 µg/kg, 0.5 µg/kg/hr (Group DEX), or ketamine 0.2 mg/kg, 0.5 mg/kg/hr (Group KET) was infused intravenously before spinal anesthesia. We recorded the time to highest sensory block level, sensory and motor regression, and hemodynamic changes.

Results

Patients in Groups KET had a significantly faster onset time of sensory block than patients in Group NS. The highest sensory block levels were not significantly different between groups. Average time of sensory regression and knee flexion, was significantly longer in the Group KET and Group DEX than the Group NS.

Conclusions

Intravenous dexmedetomidine and ketamine were found to have a similar synergistic effect with intrathecal bupivacaine. Hemodynamic stability showed better results in Group KET.

Analgesic Effects of Intravenous Ketamine during Spinal Anesthesia in Pregnant Women Undergone Caesarean Section; A Randomized Clinical Trial

Background

Suitable analgesia after cesarean section helps mothers to be more comfortable and increases their mobility and ability to take better care of their infants.

Objectives

Pain relief properties of ketamine prescription were assessed in women with elective cesarean section who underwent spinal anesthesia with low dose intravenous ketamine and midazolam and intravenous midazolam alone.

Patients and Methods

Sixty pregnant women scheduled for spinal anesthesia for cesarean section were randomized into two study groups. Ketamine (30 mg) + midazolam (1 mg = 2CC) or 1mg midazolam (2CC) alone, was given immediately after spinal anesthesia. Pain scores at first, second and third hours after CS operation, analgesic requirement and drug adverse effects were recorded in all patients.

Results

Ketamine group had significant pain relief properties in compare with control group in first hours after cesarean section (0.78 ± 1.09 vs. 1.72 ± 1.22, VAS score, P = 0.00). Total dose of meperidine consumption in women of ketamine group was significantly lower than women of control group (54.17 ± 12.86 vs. 74.44 ± 33.82 mg, P = 0.02). There were no significant drug side effects in participated patients.

Conclusions

Intravenous low-dose ketamine combined with midazolam for sedation during spinal anesthesia for elective Caesarean section provides more effective and long lasting pain relief than control group.

The Effect of Low-dose Ketamine on Post-caesarean Delivery Analgesia after Spinal Anesthesia

Background

Ketamine, an N-methyl-D-aspartate receptor antagonist, might play a role in postoperative analgesia, but its effect on postoperative pain after caesarean section varies with study design. We investigated whether the preemptive administration of low-dose intravenous ketamine decreases postoperative opioid requirement and postoperative pain in parturients receiving intravenous fentanyl with patient-controlled analgesia (PCA) following caesarean section.

Methods

Spinal anesthesia was performed in 40 parturients scheduled for elective caesarean section. Patients in the ketamine group received a 0.5 mg/kg ketamine bolus intravenously followed by 0.25 mg/kg/h continuous infusion during the operation. The control group received the same volume of normal saline. Immediately after surgery, the patients were connected to a PCA device set to deliver 25-µg fentanyl as an intravenous bolus with a 15-min lockout interval and no continuous dose. Postoperative pain was assessed using the cumulative dose of fentanyl and visual analog scale (VAS) scores at 2, 6, 24, and 48 h postoperatively.

Results

Significantly less fentanyl was used in the ketamine group 2 h after surgery (P = 0.033), but the difference was not significant at 6, 12, and 24 h postoperatively. No significant differences were observed between the VAS scores of the two groups at 2, 6, 12, and 24 h postoperatively.

Conclusions

Intraoperative low-dose ketamine did not have a preemptive analgesic effect and was not effective as an adjuvant to decrease opioid requirement or postoperative pain score in parturients receiving intravenous PCA with fentanyl after caesarean section.

Low-dose ketamine with multimodal postcesarean delivery analgesia: a randomized controlled trial

BACKGROUND

Ketamine at subanesthetic doses has analgesic properties that have been shown to reduce postoperative pain and morphine consumption. We hypothesized that intravenous ketamine 10mg administered during spinal anesthesia for cesarean delivery, in addition to intrathecal morphine and intravenous ketorolac, would decrease the incidence of breakthrough pain and need for supplemental postoperative analgesia.

METHODS

Using a randomized double-blind placebo-controlled design, healthy women scheduled for cesarean delivery receiving hyperbaric spinal bupivacaine, fentanyl and morphine were randomized to intravenous ketamine 10mg or saline following delivery. Postoperative analgesia included scheduled ketorolac and acetaminophen/hydrocodone tablets as needed for breakthrough pain. The primary outcome was the incidence of breakthrough pain in the first 24h. Secondary outcomes included the number of acetaminophen/hydrocodone tablets administered and numeric rating scale for pain (0-10).

RESULTS

Group characteristics did not differ. There was no difference in the incidence of breakthrough pain (ketamine 75% VS. saline 74%, P=0.86). There was no difference in 24-h or 72-h use of supplemental acetaminophen/hydrocodone tablets between groups. Pain scores in the first 24h were similar, but lower in the ketamine compared to the saline group 2weeks postpartum (difference -0.6, 95% CI -1.1 to -0.9).

CONCLUSIONS

We found no additional postoperative analgesic benefit of low-dose ketamine during cesarean delivery in patients who received intrathecal morphine and intravenous ketorolac. Subjects who received ketamine reported lower pain scores 2weeks postpartum.

An Intraoperative Pre-incision Single Dose of Intravenous Ketamine does not have an Effect on Postoperative Analgesic Requirements under Clinical Conditions

Evidence about the effectiveness of the N-methyl-D-aspartate antagonist ketamine to reduce postoperative acute and long-lasting pain is inconclusive. The aim of this study was to investigate effects of adding an intraoperative, pre-incision single intravenous dose of ketamine to a routine anaesthesia regimen on postoperative analgesic requirements, side-effects and persisting pain up to three months.

After obtaining Ethical Committee approval and written informed patient consent, 120 patients were included in this prospective, randomised, double-blinded, placebo-controlled study. Patients were randomised into three groups, receiving 0.15 mg/kg ketamine intravenously, 0.5 mg/kg ketamine intravenously or normal saline in groups low-dose ketamine, moderate-dose ketamine and placebo, respectively. Anaesthesia maintenance, intraoperative pain management and postoperative pain therapy were standardised. The primary study endpoint was consumption of morphine during the first 24 hours after surgery. Three months after surgery, pain scores were assessed. Data were compared by t-test and Kruskall-Wallis test with alpha = 0.05.

There was no difference between the groups in the assessed variables.

These findings indicate that with the anaesthesia regimen described, and in the doses used, a single intravenous dose of ketamine does not reduce postoperative analgesic requirement or postoperative pain at three months.

Perioperative uses of low-dose ketamine for pain management

The purpose of this article is to explore the most current literature regarding perioperative pain management uses of low-dose ketamine. Research has demonstrated significant reductions in postoperative pain scores as well as opioid consumption with low-dose ketamine administration without side effects associated with its induction doses. The availability of S(+)-ketamine with double the analgesic potency of ketamine will create even more reason for its use.

Effect of an intravenous single dose of ketamine on postoperative pain in tonsillectomy patients

BACKGROUND

Tonsillectomy has a high incidence of postoperative pain. The aim of the present study was to determine whether the use of low-dose IV ketamine, before the start of surgery or after the end of the operation, would lead to significantly improved pain control after tonsillectomy in pediatric patients.

METHODS

Ninety children, 5-7 years old, scheduled for elective tonsillectomy were randomly assigned to one of three groups of 30 patients each; groups I, II and III. Patients in group I received no ketamine. Patients in group II received 0.5 mg x kg(-1) of ketamine before the surgical start and for group III the same dose was given after the operation ended. Postoperative pain was scored by the Oucher scale. Systolic and diastolic pressures and heart rate were recorded perioperatively. Unwanted side effects were recorded by the ward staff personnel on a 24-h study-specific questionnaire. Statistical tests consisted of Student's t-test, chi-square and anova as appropriated.

RESULTS

The number of patients complaining of pain was greater in group I compared with patients in groups II and III with a significative statistical difference (P < 0.05). The degree of postoperative pain was significantly higher in patients of group I compared with groups II and III (P < 0.05). Eight patients in group I needed rescue doses of morphine, three for group II and none for group III. In group I, three of eight patients required two doses of morphine during the first 249 h postoperatively. No unwanted side effects were noted.

CONCLUSIONS

The use of a single small dose of ketamine in a pediatric population undergoing tonsillectomy could reduce the frequency or even avoid the use of rescue analgesia in the postoperative period independent of whether used before or after the surgical procedure.

Postcesarean analgesia: effective strategies and association with chronic pain

PURPOSE OF REVIEW

The management of postoperative pain after cesarean section slightly differs from that of the general surgical population, specifically women need to recover quickly to take care of their newborn baby. Optimal pain management is imperative for the success of immediate-term and long-term rehabilitation and this principle applies to obstetric patients. There is growing evidence that perioperative pain management has consequences extending well beyond the immediate recovery period. Unrelieved postoperative pain is a striking risk factor for the development of residual pain.

RECENT FINDINGS

A recent study has highlighted that chronic pain may be a significant clinical problem after cesarean section. Among the risk factors, recalls of severe acute postoperative pain led to the reconsideration of postoperative pain management after cesarean delivery. Current published data agree that drug combinations, that is, multimodal or balanced analgesia, are mandatory to achieve satisfactory and effective pain relief with reduced side effects.

SUMMARY

The use of balanced analgesia has significantly improved acute pain management after cesarean section. Future studies should extend their investigations beyond the first 48 h and consider the long-term effects of different analgesic regimens, that is, those that alter the development of residual pain.