The effect of epidural injection speed on epidural pressure and distribution of solution in anesthetized dogs

Dural Puncture Epidural with 25-G Spinal Needles versus Conventional Epidural Technique in Conjunction with PIEB for Labor Analgesia: A Randomized Trial

Purpose

To compare the effect of Dural puncture epidural (DPE) and conventional epidural (EP), in conjunction with programmed intermittent epidural bolus (PIEB) and low-concentration ropivacaine strategy.

Methods

After written informed consent was obtained, healthy nulliparous women with singleton pregnancies, vertex presentation at 38-42 weeks' gestation, cervical dilation of 3-5 cm, and a desire for pain relief were randomly assigned to DPE or EP group. Dural matter was puncture with 25G Whitacre needle in DPE group. Analgesia was initiated with 15 mL of 0.1% ropivacaine over 5 minutes and was maintained by PIEB (8 mL of 0.08% ropivacaine with 2 μg/mL fentanyl every 40 min). Primary outcome was the percentage of adequate analgesia, defined as NRPS ≤1, at 30 minutes after the initiation of the epidural bolus.

Results

Out of 130 enrolled parturients, 127 were included in final analysis (64 in DPE group, 63 in EP group). No significant difference was found in percentage of adequate analgesia at 30 minutes (risk ratio: 1.09; 95% confidence interval: 0.90-1.31; P = 0.366). At 8, 12, 14, and 16 minutes, percentage of adequate analgesia was higher in DPE group (P = 0.023, 0.027, 0.016 and 0.033, respectively). NPRS scores in DPE group decreased more dramatically within the first 30 min. The incidence of S2 sensory blocks at 20 and 30 min in DPE group was higher (P = 0.010 and 0.006, respectively). There were no differences in patient satisfaction, delivery mode, adverse effects, fetal bradycardia, and Apgar scores at 1 and 5 minutes.

Conclusion

The combination of the use of DPE technique with 25G spinal needle and PIEB technique for labor analgesia appears to enhance the quality of labor analgesia by accelerating onset and providing improved sacral blockade, without increasing adverse effects.

Direct Comparison of Peak Bulk Flow Rate of Programmable Intermittent Epidural Bolus and Manual Epidural Bolus Using a Closed-End Multiorifice Catheter: An Experimental Study

BACKGROUND

The programmable intermittent epidural bolus (PIEB) has been popularized as the optimal delivery technique for labor analgesia. Suggested advantages of this method are less local anesthetic consumption, improved maternal satisfaction, potentially shorter duration of labor, and decreased workload requirements for the anesthesia providers. However, a manual bolus is still routinely used for breakthrough pain when the PIEB is underperforming.

METHODS

We conducted a laboratory-based study to quantify the flow through a multiorifice epidural catheter using the PIEB setting on an epidural pump compared to the manual epidural bolus. Four syringe volumes, 3, 5, 10, and 20 mL, were selected for this experiment. The flow in a manual bolus was also studied with and without the presence of an epidural catheter filter. A generalized estimating equation analysis was done to compare data between the groups.

RESULTS

Regardless of the syringe size, there was a several-fold increase in flow when a manual bolus was used compared to a pump-administered dose, with the highest difference in the peak flow rate observed in 3-mL boluses with up to a 12-fold difference, while the difference was, at most, 7-fold in 5-mL and 10-mL boluses. Manual boluses without a filter achieve a mean peak flow rate higher than manual boluses with a filter.

CONCLUSIONS

Our study found that manual boluses produced a higher flow rate compared to the CADD-Solis epidural pump (Smiths Medical). This study also found that the placement of a particulate filter reduces the flow rates generated while bolusing. Bulk flow rate is directly correlated with induced pressure and solution spread. Because higher bolus pressure has been shown to provide a more efficient distribution of local anesthetic and more efficient pain relief, these results may have impactful clinical significance and will pave the way for future studies.

Analgesic, cardiorespiratory effects and motor block characteristics of epidural levobupivacaine alone or in combination with methadone or dexmedetomidine in bitches undergoing unilateral total mastectomy

The aim of this study was to evaluate the latency, extent of analgesia, and duration of motor block of levobupivacaine alone and combined with methadone or dexmedetomidine after epidural administration during and after mastectomy in dogs. Twenty-four mature, mixed-breed female dogs were randomly divided into three experimental groups with eight animals each, according to the agents used in lumbosacral epidural analgesia: levobupivacaine 0.75% alone (1.5mg/kg - control group), levobupivacaine 0.75% (1.5 mg/kg) + methadone 1% (0.3 mg/kg), or levobupivacaine 0.75% (1.5 mg/kg) + dexmedetomidine 0.05% (3 µg/kg). During surgery, cardiorespiratory parameters were evaluated. Rescue analgesia was given when there were signs of nociception and was necessary in all three treatment groups. Since all animals received rescue analgesia during the surgery and immediately post-surgery, the duration of the sensitive block were not evaluated. The extent of sensory block was between the 12º and 13º thoracic vertebrae for the control group, 7º thoracic vertebra to 5º lumbar vertebra (methadone group), and 8º thoracic vertebra to 4º lumbar vertebra for the dexmedetomidine group. Methadone or dexmedetomidine combined with levobupivacaine increased the extent of the sensory block and the duration of the motor block in bitches when administered via the epidural route.

Epidural Volume of Injectate Using a Dose Regimen Based on Occipito-Coccygeal Spinal Length (OCL): Randomized Clinical Study Comparing Different Ropivacaine Concentrations, with or without Morphine, in Bitches Undergoing Total Unilateral Mastectomy

A prospective, randomized clinical trial was designed to compare four epidural treatments in dogs undergoing total unilateral mastectomy. The epidural volume of injectate was based on the individual occipito-coccygeal length (OCL) aiming to reach the first thoracic vertebra (T1). The first ten dogs were allocated in a control group (C) and did not receive epidural treatment. Subsequently, forty dogs were randomly allocated in four groups of ten: epidural ropivacaine 0.5% (R0.5%); morphine 0.1 mg kg−1 plus ropivacaine 0.5% (MR0.5%); morphine 0.1 mg kg−1 plus ropivacaine 0.35% (MR0.35%); morphine 0.1 mg kg−1 plus ropivacaine 0.25% (MR0.25%). Intraoperatively, isoflurane requirement (1.3% vs. <1.1% FE’Iso) and fentanyl requirement (9.8 vs. <1.1 µg kg−1 h−1) were significantly higher in C group compared to all epidural groups. Postoperatively, methadone requirement was higher (1.8 mg kg−1 vs. <0.8 mg kg−1) for C group compared to all epidural treatment groups. The ability to walk and to urinate returned 4 h earlier in MR0.35% and MR0.25%. The mean epidural volume of ropivacaine, using a dose regimen based on OCL, to reach T1 was about 0.15 mL cm−1. The addition of morphine further reduced the methadone requirement, without affecting urinary and motor functions.

Regional anesthesiological support for the implementation of surgical interventions in the abdomen of dogs

Widespread use of surgical interventions in the abdomen of dogs determines the relevance of the study. The research tested the influence of therapeutic epidural blockade with 0.2% bupivacaine after surgical interventions on the background of potentiated local anaesthesia on the body of clinically healthy dogs undergoing ovariohysterectomy. In the control group postoperative analgesia was performed with the nonsteroidal anti-inflammatory drug rimadyl on the background of potentiated thiopental anaesthesia. Wound healing rates were determined in 10 animals of both control and experimental groups; blood counts and the level of inflammatory response were indicated in 5 animals of each group. The dynamics of reparative processes and complete wound healing in dogs of the experimental group occurred earlier than in animals of the control group, which confirmed the fact that the use of bupivacaine had a beneficial effect on tissue regeneration. The results of morphological and biochemical parameters of blood in animals of the experimental group manifested only an increase of leukocytes by 1.58 times, fibrinogen by 2.02 times, while in dogs of the control group the level of erythrocytes, haemoglobin and hematocrit decreased, leukocytes increased by 1.74 times, platelets decreased by 2.87 times and fibrinogen increased by 1.72 times. Among the stress response markers in the control group there was a 1.94 times increase in glucose level after surgery. In the experimental group there was a decrease in the intensity of the inflammatory reaction in dogs, accompanied by an increase of anti-inflammatory interleukin 4 (IL-4) only on the seventh day – 1.86 times, while in the control group the level of anti-inflammatory interleukin 1 receptor antagonist (IL-1RA) after three days increased by 2.30 times, after seven days – by 2.48 times, and the level of proinflammatory interleukin 6 (IL-6) after surgery increased by 2.57 times. It will be promising to conduct further research on the influence of therapeutic blockades with bupivacaine in animals in cases of various surgical interventions and pathological conditions, which will lead to faster recovery of animals and alleviate pathological processes.

Bloqueio motor e sensitivo da lidocaína ou da ropivacaína peridural em cães

RESUMO Objetivou-se avaliar o bloqueio sensitivo e motor da administração peridural de 0,2mL/kg de duas concentrações de ropivacaína em comparação à lidocaína em cães. Utilizaram-se 24 cães, distribuídos em quatro grupos: NaCl a 0,9% (GS), lidocaína a 2% (GL), ropivacaína a 0,5% (GR5) e ropivacaína a 0,75% (GR7,5). Avaliaram-se a presença de movimentação espontânea, deambulação, sensibilidade superficial e profunda nos momentos cinco, 10, 15, 20, 25, 30, 45, 60, 90, 120, 180, 240 e 300 minutos após peridural. O retorno à movimentação espontânea foi semelhante entre GL (42,50 ± 6,12) e GR7,5 (69,2 ± 58,9). O tempo para deambulação foi mais prolongado em GR7,5 (107,5 ± 79,3) que em GS (9,2 ± 3,8) e em GR5 (32,5 ± 20,9). O retorno da sensibilidade profunda foi maior em GR 7,5 (152,5 ± 89,2) que em GS (5,8 ± 2,0), GR5 (46,7 ± 46,3) e GL (52,5 ± 20,7). O tempo de retorno da sensibilidade superficial foi maior em GR7,5 (205,0 ± 129,3) que em GS (7,5 ± 2,7), GL (72,5 ± 19,9) e GR5 (97,5 ± 55,1). Apesar do retorno precoce da movimentação, ropivacaína 0,75% está relacionada a tempo prolongado de recuperação da função muscular e bloqueio sensitivo mais prolongado que lidocaína e ropivacaína 0,5%.

Dispersão da lidocaína administrada por via epidural em cães posicionados em decúbito lateral ou esternal

RESUMO O objetivo do estudo foi verificar clinicamente a dispersão da lidocaína no espaço epidural de cães posicionados em diferentes decúbitos. Foram utilizados 16 cães, com peso médio de 17,5 quilogramas. Esses foram tranquilizados com acepromazina, anestesiados com propofol e alocados em dois grupos, conforme o decúbito de posicionamento: decúbito esternal (GE) e decúbito lateral direito (GLD). Ambos os grupos receberam lidocaína a 2%, no volume de 0,25mL/kg, e permaneceram no mesmo decúbito por 20 minutos. Em seguida, avaliou-se o bloqueio dos membros pélvicos e a extensão do bloqueio, a partir da sétima vértebra lombar, por meio de pinçamento interdigital e do panículo paravertebral. Foi, então, realizada cirurgia de orquiectomia. Após tal procedimento, avaliou-se o tempo total de bloqueio dos membros pélvicos. Todos os cães apresentaram bloqueio bilateral, sem diferenças quanto à extensão cranial entre os grupos, sendo a mediana de 7,5 (1-14) vértebras para GE e de 4 (1-14) para GLD. O tempo de bloqueio dos membros direito e esquerdo foi de 123 ± 26 e 130 ± 20 minutos, para GE, e de 120 ± 21 e 121 ± 20 minutos, para GLD, sem diferenças entre os grupos ou entre os membros. Conclui-se que o decúbito não interfere na distribuição da lidocaína administrada por via epidural.

Epidural and Spinal Anesthesia

Epidural and spinal anesthesia with a combination of local anesthetics and opioids (when available) is a commonly used technique in veterinary medicine and a safe one when practiced under strict guidelines. It is a valuable tool in the analgesic armamentarium and can greatly extend the ability to provide analgesia and reduce postoperative opioid requirements. As with all regional anesthetic techniques, clinical experience should be gained in order to practice it efficiently, and care should be taken to minimize the risks and complications associated with its use.

Effectiveness of continuous hypertonic saline infusion with an automated infusion pump for decompressive neuroplasty: a randomized clinical trial

Background

Hypertonic saline (HS) injections for decompressive neuroplasty (DN) can cause pain. We assessed whether a continuous infusion of HS through an infusion pump would reduce injection-related pain compared with repeated bolus administrations.

Methods

Fifty patients scheduled for DN were randomized to either the bolus injection or the continuous infusion group. After appropriately placing the epidural catheter, 4 mL of 5% NaCl was injected as four boluses of 1 mL each at 15-minute intervals or infused over 1 hour using an infusion pump. The severity of pain induced by HS injection, as measured by the 11-point numerical rating scale (NRS), was the primary outcome. The severity of low back or lower extremity pain, as measured by the 11-point NRS and Oswestry Disability Index (ODI), 3 months following the procedure, was the secondary outcome.

Results

Data from 21 patients in the bolus group and 23 in the continuous infusion group were analyzed. No statistically significant difference in injection-related pain was identified between the two groups during the initial HS administration (P = 0.846). However, there was a statistically significant reduction in injection-related pain in the continuous infusion group compared to the bolus injection group from the second assessment onwards (P = 0.001, < 0.001, and < 0.001, respectively). No significant between-group differences in the NRS and ODI scores 3 months post-procedure were noted (P = 0.614 and 0.949, respectively).

Conclusions

Our study suggests that administering HS through a continuous infusion is a useful modality for reducing HS injection-related pain during DN.

Epidural anesthesia and analgesia in small animal practice: An update

Epidural anesthesia is a commonly performed technique in both human and veterinary medicine. The technique is relatively simple following appropriate training and provides anesthesia and analgesia for acute and chronic pain. Several drug combinations have been administered by this route with variable success and duration. Multiple techniques to guide or confirm correct epidural needle placement are discussed in this article, as well as anatomical features of the epidural space, effect of drug volume and concentration, and adverse effects of the technique in small animal practice. This article is not an exhaustive review of the literature, but an update of some new findings over the last decade.

An Update on Drugs Used for Lumbosacral Epidural Anesthesia and Analgesia in Dogs

This review aims to report an update on drugs administered into the epidural space for anesthesia and analgesia in dogs, describing their potential advantages and disadvantages in the clinical setting. Databases searched include Pubmed, Google scholar, and CAB abstracts. Benefits of administering local anesthetics, opioids, and alpha₂ agonists into the epidural space include the use of lower doses of general anesthetics (anesthetic “sparing” effect), perioperative analgesia, and reduced side effects associated with systemic administration of drugs. However, the potential for cardiorespiratory compromise, neurotoxicity, and other adverse effects should be considered when using the epidural route of administration. When these variables are considered, the epidural technique is useful as a complementary method of anesthesia for preventive and postoperative analgesia and/or as part of a balanced anesthesia technique.

The volume effect of lidocaine on thoracic epidural anesthesia in conscious Beagle dogs

OBJECTIVE

To evaluate the volume effect of local anesthetic solution on thoracic epidural analgesia in dogs.

STUDY DESIGN

Prospective, experimental trial.

ANIMALS

Five healthy adult Beagle dogs weighing 9.7 ± 1.3 kg.

METHODS

A catheter was inserted into the seventh thoracic epidural space using a lumbosacral approach, and secured with suture under total intravenous (IV) anesthesia with propofol. Each dog was administered four volume treatments (0.05, 0.10, 0.15 and 0.20 mL kg(-1)) of 2% lidocaine via the catheter at 12 hour intervals. In every treatment, dogs were re-anesthetized with propofol (6 mg kg(-1), IV) and isoflurane, and received iohexol at each volume to visualize the epidural distribution (ED) through computed tomography. Three hours after epidurography, when dogs had recovered from anesthesia, the appropriate volume of lidocaine was injected through the catheter, and sensory blockade (SB) in dermatomes was evaluated by pinching with a mosquito forceps. Results were presented as median (range), and the volume effect on ED and SB was analyzed with one-way Kruskal-Wallis anova.

RESULTS

In proportion to volumes (0.05, 0.10, 0.15 and 0.20 mL kg(-1)), there were significant increases in the extent of ED from 7.4 (5.5-9.0) to 10.4 (8.0-12.0), 13.2 (12.5-13.0), and 15.2 (13.0-18.0) vertebrae, respectively, p < 0.001, and in SB from 2.7 (1.0-5.0) to 6.8 (4.5-10.5), 9.9 (6.5-13.0), and 13.1 (11.0-15.0) dermatomes, respectively, p < 0.001. Unilateral ED and SB were observed in all treatments with various grades, and this distribution was more frequent in the low volume treatments. In the high volume treatments, temporary complications including Horner's syndrome, ataxia, paraplegia, depression, stupor, and intermittent cough occurred often.

CONCLUSIONS AND CLINICAL RELEVANCE

The increase in volume of local anesthetic solution improved SB by resulting in more consistent bilateral dermatome blockade as well as an extended blockade. However, caution should be exerted, as higher volume injections of lidocaine caused side effects in all dogs.