Effective Dose Range of Intrathecal Isobaric Bupivacaine to Achieve T5–T10 Sensory Block Heights for Elderly and Overweight Patients: An Observational Study

Background and Objectives: The dose selection for isobaric bupivacaine determines the success of spinal anesthesia (SA). A dose higher than the optimal dose causes high SA, whereas an underdose leads to inadequate spread of cephalad. As it involves anatomical and physiological alterations, the dosing should be reduced with advancing age and body mass index values. Therefore, this study aimed to demonstrate the association between the isobaric bupivacaine dose and block height, and to determine the dose intervals of bupivacaine to achieve the T5–T10 sensory block with a low probability of high SA in elderly and overweight patients. Material and Methods: This retrospective observational study recruited 1079 adult patients who underwent SA with 0.5% isobaric bupivacaine from 2018 to 2021. The patients were divided into four categories: category 1 (age < 60, BMI < 25), category 2 (age < 60, BMI ≥ 25), category 3 (age ≥ 60, BMI < 25), and category 4 (age ≥ 60, BMI ≥ 25). The bupivacaine dose and sensory block height (classified into three levels: high (T1–T4), favorable (T5–T10), and low (T11–L2)) were recorded. Results: The sensory block level increased significantly with increasing doses of bupivacaine for patients in categories 1 and 2. The suggested dose ranges for the favorable block heights were 15–17 and 10.5–16 mg in patient categories 1–2 and 3–4, respectively. In these dose ranges, the probability range of high SA was 10–15%. Conclusions: The sensory block height following SA was associated with the bupivacaine dose in patients aged <60 years. Regardless of the BMI, the suggested dose ranges of 0.5% isobaric bupivacaine are 15–17 mg (3.0–3.4 mL) and 10.5–16 mg (2.1–3.2 mL) for patients aged <60 and ≥60 years, respectively.

Obesity decreases the EC50 of epidural ropivacaine when combined with dexmedetomidine for labor analgesia

OBJECTIVES

This study aims to estimate the EC50 of ropivacaine when co-administered with dexmedetomidine for epidural labor analgesia in antepartum obese and non-obese parturients.

METHODS

Sixty parturients scheduled for epidural labor analgesia were enrolled and divided into antepartum obesity (AO) and control (CON) groups, according to their body mass index at labor. Both groups received 0.5 µg/mL dexmedetomidine with ropivacaine as anesthetics. The concentration of ropivacaine was initially set at 0.125% and varied by 0.01% according to the up-and-down rule for sequential allocation. Hemodynamic parameters were monitored and pain intensity was assessed using a visual analog scale.

RESULTS

When co-administered with dexmedetomidine, the EC50 of ropivacaine was 0.095% (95% confidence interval [CI]: 0.090-0.100%) and 0.070% (95% CI: 0.062-0.076%) in CON and AO groups, respectively. There was a significant difference between the two groups (P < 0.001). EC95 values of ropivacaine were 0.084% (95% CI: 0.077-0.122%) and 0.106% (95% CI: 0.101-0.128%) in AO and CON groups, respectively.

CONCLUSION

Patients with antepartum obese may require decreased ropivacaine concentration for epidural labor analgesia when co-administered with 0.5 µg/mL dexmedetomidine.

Peri-operative management of overweight and obese children and adolescents

Obesity has become endemic, even in children. Systemic complications associated with obesity include metabolic syndrome, cardiovascular disease, and respiratory compromise. These comorbidities require adequate investigation, targeted optimisation, and, if surgery is required, specific management during the peri-operative period. Specific peri-operative strategies should be used for paediatric patients who are overweight or obese to prevent postoperative complications, and optimising the respiratory function during surgery is particularly crucial. This Review aims to provide up-to-date information on peri-operative management for physicians who are caring for children and adolescents (usually younger than 18 years) who are overweight or obese undergoing surgery, including bariatric surgery. We have particularly focussed on the physiological consequences of obesity-namely, obstructive sleep apnoea, respiratory compromise, and pharmacological considerations.

Effect of equipotent doses of bupivacaine and ropivacaine in high-fat diet fed neonatal rodent model

OBJECTIVES

The increase in the prevalence of obesity presents a significant health and economic problem. Obesity has been reported to be a major contributor to variety of chronic diseases. Childhood obesity has been rising over the past decades leading to various complications in health. Millions of infants and children undergo surgery every year on various health grounds. The present investigation was undertaken to evaluate the effect of spinal anesthesia of equipotent doses of ropivacaine and bupivacaine on over-weight neonatal rats.

METHODS

The Sprague-Dawley rat pups were overfed on high fat diet to induce obesity. Behavioral assessments for sensory and motor blockade was made by evaluating thermal and mechanical withdrawal latencies at various time intervals following intrathecal injections of bupivacaine (5.0mg·kg^-1) and ropivacaine (7.5mg·kg^-1) in P14 rats. Spinal tissue was analyzed for apoptosis by determination of activated caspase-3 using monoclonal anti-activated caspase-3 and Fluoro-Jade C staining. Long-term spinal function in P30 rat pups was evaluated.

RESULTS

Exposure to intrathecal anesthesia in P14 increased thermal and mechanical latencies and was observed to increase apoptosis as presented by increase in activated caspase-3 and Fluro-Jade C positive cells. Significant alterations in spinal function were observed in high fat diet-fed pups as against non-obese control pups that were on standard diet. Bupivacaine produced more pronounced apoptotic effects on P14 pups; ropivacaine however produced long lasting effects as evidenced in motor function tests at P30.

CONCLUSION

Ropivacaine and bupivacaine induced spinal toxicity that was more pronounced in over-fed rat pups as against normal controls.

[Effect of equipotent doses of bupivacaine and ropivacaine in high-fat diet fed neonatal rodent model]

OBJECTIVES

The increase in the prevalence of obesity presents a significant health and economic problem. Obesity has been reported to be a major contributor to variety of chronic diseases. Childhood obesity has been rising over the past decades leading to various complications in health. Millions of infants and children undergo surgery every year on various health grounds. The present investigation was undertaken to evaluate the effect of spinal anesthesia of equipotent doses of ropivacaine and bupivacaine on over-weight neonatal rats.

METHODS

The Sprague-Dawley rat pups were overfed on high fat diet to induce obesity. Behavioral assessments for sensory and motor blockade was made by evaluating thermal and mechanical withdrawal latencies at various time intervals following intrathecal injections of bupivacaine (5.0mg·kg^-1) and ropivacaine (7.5mg·kg^-1) in P14 rats. Spinal tissue was analyzed for apoptosis by determination of activated caspase-3 using monoclonal anti-activated caspase-3 and Fluoro-Jade C staining. Long-term spinal function in P30 rat pups was evaluated.

RESULTS

Exposure to intrathecal anesthesia in P14 increased thermal and mechanical latencies and was observed to increase apoptosis as presented by increase in activated caspase-3 and Fluro-Jade C positive cells. Significant alterations in spinal function were observed in high fat diet-fed pups as against non-obese control pups that were on standard diet. Bupivacaine produced more pronounced apoptotic effects on P14 pups; ropivacaine however produced long lasting effects as evidenced in motor function tests at P30.

CONCLUSION

Ropivacaine and bupivacaine induced spinal toxicity that was more pronounced in over-fed rat pups as against normal controls.

The Levels and Duration of Sensory and Motor Blockades of Spinal Anesthesia in Obese Patients That Underwent Urological Operations in the Lithotomy Position

Obesity has a significant effect on the cephalic spread of a spinal block (SB) due to a reduction in cerebrospinal fluid (CSF). SB is controlled by the tissue blood flow in addition to the CSF. Some positions and techniques of surgery used can cause changes in hemodynamics. We investigated effects of hemodynamic changes that may occur during Transurethral prostate resection (TUR-P) and lithotomy position (LP) at the SB level in obese versus nonobese individuals. Sixty patients who had undergone TUR-P operation under spinal anesthesia were divided into a nonobese (BMI < 25 kg/m(2), Group N) or obese (BMI ≥ 30 kg/m(2), Group O) group. SB assessments were recorded afterthe LP. SB at 6 and 120 min and the peak SB level were compared between two groups. Hemodynamics were recorded after LP. Peak and 6 min SB levels were similar between the groups, while 120 min SB levels were significantly higher for Group O (P < 0.05). Blood pressure (BP) after the LP was significantly higher for Group N (P < 0.05). LP and TUR-P increased the BP in Group N when compared to Group O. The increase in hemodynamics enhances the blood flow in the spinal cord and may form similar SB levels in nonobese patients to those in obese patients. However, SB time may be longer in obese patients.

Obesity is independently associated with spinal anesthesia outcomes: a prospective observational study

The influence of body-mass index (BMI) on spinal anesthesia is still controversial, with discrepant results reported in previous studies. To compare spinal anesthesia in obese and non-obese subjects, the anesthesia profiles in patients who underwent spinal anesthesia using intrathecal hyperbaric bupivacaine were compared. A total of 209 patients undergoing elective total knee replacement arthroplasty (TKRA) surgery under spinal anesthesia were divided into an NO (non-obese) group (BMI < 30 kg/m², n = 141) and an O (obese) group (BMI ≥ 30 kg/m², n = 68). Anesthesia was deemed successful if a bilateral T12 sensory block occurred within 15 minutes of intrathecal drug administration, and if the level of sensory block was higher than T12 when the surgery ended. Logistic regression analysis with multiple variables known to influence spinal anesthesia was performed to identify which parameters independently determined the spinal anesthesia outcome. Similar doses of bupivacaine were administered to the NO and O groups. The incidence of anesthesia failure was significantly lower in the O group [n = 43 (30.5%) in the NO group vs. n = 10 (18.9%) in the O group, p = 0.014]. The independent predictors for successful anesthesia in all patients were dose of hyperbaric bupivacaine [odds ratio (OR) 2.12, 95% CI: 1.64–2.73] and obese status (BMI ≥ 30 kg/m², OR 2.86, 95% CI: 1.25–6.52). Time to first report of postoperative pain and time to first self-void were significantly longer in the O group. These results suggest that the duration of block with hyperbaric bupivacaine is prolonged in obese patients and obesity is independently associated with spinal anesthesia outcomes, as is bupivacaine dosage. A further study enrolling patients with morbid obesity and using a fixed bupivacaine dosage is required to confirm the effect of obesity on spinal anesthesia.

Obesity in orthopedics and trauma surgery

In 2012, 32.3% of the French population over 18 years of age was considered overweight (25 ≤ BMI<30 kg/m(2)) and 15% obese (BMI ≥ 30 kg/m(2)). Worldwide, 2.8 million people die every year from the complications of obesity. In 2008, the prevalence of obesity was almost double that of 1980. Obesity is a genuine concern for the orthopedic surgeon, as it affects bones and soft tissues on the biomechanical and biochemical level. In traumatology, low-energy trauma is more frequent in obese patients and induces complex comminutive fractures of the extremities. In orthopedics, obesity is an independent risk factor for osteoarthritis, particularly for the knee joint. The goals of this review are to describe specific aspects of the care of obese patients in trauma and orthopedics surgery during the pre-, intra- and postoperative periods, as well as the risk-benefit ratio related to the treatment of the obese patients.