Prolonging the duration of single-shot intrathecal labour analgesia with morphine: A systematic review

Pharmacological and clinical implications of local anaesthetic mixtures: a narrative review

Various techniques have been explored to prolong the duration and improve the efficacy of local anaesthetic nerve blocks. Some of these involve mixing local anaesthetics or adding adjuncts. We did a literature review of studies published between 01 May 2011 and 01 May 2021 that studied specific combinations of local anaesthetics and adjuncts. The rationale behind mixing long- and short-acting local anaesthetics to hasten onset and extend duration is flawed on pharmacokinetic principles. Most local anaesthetic adjuncts are not licensed for use in this manner and the consequences of untested admixtures and adjuncts range from making the solution ineffective to potential harm. Pharmaceutical compatibility needs to be established before administration. The compatibility of drugs from the same class cannot be inferred and each admixture requires individual review. Precipitation on mixing (steroids, non-steroidal anti-inflammatory drugs) and subsequent embolisation can lead to serious adverse events, although these are rare. The additive itself or its preservative can have neurotoxic (adrenaline, midazolam) and/or chondrotoxic properties (non-steroidal anti-inflammatory drugs). The prolongation of block may occur at the expense of motor block quality (ketamine) or block onset (magnesium). Adverse effects for some adjuncts appear to be dose-dependent and recommendations concerning optimal dosing are lacking. An important confounding factor is whether studies used systemic administration of the adjunct as a control to accurately identify an additional benefit of perineural administration. The challenge of how best to prolong block duration while minimising adverse events remains a topic of interest with further research required.

Spinal Anesthesia Using Ultra-Low-Dose Isobaric Bupivacaine with Intrathecal Morphine-Fentanyl for Bilateral Low Extremity Procedures in a Geriatric Patient with Recent Myocardial Infarction and Percutaneous Coronary Intervention

A recent inferior ST-elevation myocardial infarction and percutaneous coronary intervention in an elderly female patient scheduled for bilateral lower extremity operations simultaneously represent significant risks for re-infarction and mortality. Our index patient required an above-knee amputation of the left leg to prevent infection/progressing gangrene as well as application of a back-slab for the conservative management of a fractured right femur. We employed spinal injection of ultra-low-dose 0.5% isobaric bupivacaine 4 mg with morphine 75 mcg plus fentanyl 10 mcg which provided adequate anesthesia for radical amputation, effective postoperative analgesia and good hemodynamic stability.

Outcomes of intrathecal analgesia in multiparous women undergoing normal vaginal delivery: A randomised controlled trial

Background and Aims

Although intrathecal analgesia is an effective option during labour, there is a need to establish sustainable and assured analgesia during the entire labour process. We aimed to assess the effect of adding dexmedetomidine, fentanyl or morphine to low-dose bupivacaine-dexamethasone for intrathecal labour analgesia in multiparous women.

Methods

This was a triple-blind, randomised controlled trial that included 140 multiparous women. Eligible women were randomly allocated to have intrathecal bupivacaine-dexamethasone with dexmedetomidine (group D), fentanyl (group F), morphine (group M) or saline (placebo) (group C). The duration of analgesia, intrathecal block characteristics and maternal and foetal outcomes were assessed and analysed.

Results

The longest analgesia duration and S1 regression time was recorded in group D followed by groups M, F and C, respectively, with statistical significance between all of them (P < 0.001). The shortest analgesia onset time and the highest sensory levels were recorded in group D followed by group F then group M with statistical significance between all of them (P < 0.001 and 0.003, respectively). Visual analogue scale values were comparable among groups M, F and D (P > 0.05) at most of the measurement time points and at the peak of the last uterine contraction before delivery while being significantly lower than those in group C (P < 0.001). However, there were similar motor block characteristics and normal neonatal outcomes in all groups.

Conclusion

In comparison to morphine and fentanyl, dexmedetomidine addition to intrathecal bupivacaine-dexamethasone significantly prolonged the duration and accelerated the onset of labour analgesia, with a good maternal and neonatal outcome.

Postoperative Analgesic Effects of Different Doses of Epidural Hydromorphone Coadministered with Ropivacaine after Cesarean Section: A Randomized Controlled Trial

Purpose

Single dose of epidural hydromorphone has been introduced to serve as an alternative method for postcesarean section analgesia. However, optimal dose of epidural hydromorphone remains unknown. Hence, we evaluated and compared the analgesic and adverse effects of postoperative different doses of epidural hydromorphone coadministered with ropivacaine after cesarean section.

Methods

Eighty term parturients with elective cesarean section under epidural anesthesia were allocated into four groups. Epidural analgesia was administered with an epidural bolus of either 0 mg (group H0), or 0.2 mg (group H1), or 0.4 mg (group H2), or 0.6 mg (group H3) hydromorphone coadministered with ropivacaine. The primary outcome was the visual analogue pain scores (VAPSs) and rescue opioid consumption (PCIA with sulfentanil) in 24 hours. Adverse effects such as respiratory depression, pruritus, nausea, and vomiting were recorded.

Results

The VAPSs of group H1 at 2, 4, 6, 12 h and 24 h after surgery was similar to group H0. The VAPSs of group H2 at 4 and 6 h postoperatively were significantly decreased when compared to group H0. But, the VAPSs of group H2 at 2, 12, and 24 h postoperatively were similar to those of group H0. The VAPSs of group H3 at 4, 6, 12 h, and 24 h after surgery were significantly decreased when compared to those of group H0. The total sulfentanil consumption in 24 hours was 90 ± 26 μg in group H0, 75 ± 29 μg in group H1, 54 ± 32 μg in group H2, and 15 ± 16 μg in group H0. Adverse effects were comparable in the four groups.

Conclusions

Epidural administration of 0.6 mg hydromorphone coadministered with ropivacaine after cesarean section provided satisfactory pain relief with less sulfentanil consumption. This trial is registered with ChiCTR-IPR-16010026.

Neuraxial opioids as analgesia in labour, caesarean section and hysterectomy: A questionnaire survey in Sweden

Background: Neuraxial opioids improve labour analgesia and analgesia after caesarean section (CS) and hysterectomy. Undesirable side effects and difficulties in arranging postoperative monitoring might influence the use of these opioids. The aim of the present survey was to assess the use of intrathecal and epidural morphine in gynaecology and obstetrics in Sweden. Methods: A questionnaire was sent to all anaesthetic obstetric units in Sweden concerning the use and postoperative monitoring of morphine, sufentanil and fentanyl in spinal/epidural anaesthesia. Results: A total of 32 of 47 (68%) units responded representing 83% of annual CS in Sweden. In CS spinal anaesthesia, 20/32 units use intrathecal morphine, the most common dose of which was 100 μg (17/21). Intrathecal fentanyl (10-20 μg) was used by 21 units and sufentanil (2.5 -10 μg) by 9/32 of the responding units. In CS epidural anaesthesia, epidural fentanyl (50-100 μg) or sufentanil (5-25 μg) were commonly used (25/32), and 12/32 clinics used epidural morphine, the majority of units used a 2 mg dose. Intrathecal morphine for hysterectomy was used by 20/30 units, with 200 μg as the most common dose (9/32). Postoperative monitoring was organized in adherence to the National Guidelines; the patient is monitored postoperative care or an obstetrical ward over 2-6 hours and up-to 12 hours in an ordinary surgical ward. Risk of respiratory depression/difficult to monitor was a reason for not using intrathecal opioids. Conclusions: Neuraxial morphine is used widely in Sweden in CS and hysterectomy, but is still restricted in some units because of the concern for respiratory depression and difficulties in monitoring.