Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients

INTRODUCTIONRegional anaesthesia is a safe, inexpensive technique, widely used for lower limb orthopaedic surgery due to the advantage of prolonged post-operative pain relief. Combination with adjuncts [1][2][3][4][5] like epinephrine, clonidine, neostigmine, opioids, midazolam and magnesium [6][7][8][9][10][11][12][13][14][15][16][17][18][19] have been used to prolong analgesia and reduce the incidence of adverse events. These spinal adjuvants allow the use of lower dose of local anaesthetic agents, prolong and intensify the subarachnoid block and offer hemodynamic stability. Opioids such as fentanyl are commonly used as additive to local anaesthetics to prolong the duration and intensify the effects of subarachnoid block. However significant side effects of opioids such as pruritis, urinary retention, respiratory depression, hemodynamic instability and occasionally severe nausea and vomiting may limit their use. Newer methods of prolonging the duration of subarachnoid block and reducing post-operative analgesic requirements are of special interest in major surgical procedures.One of the mechanisms implicated in the persistence of postoperative pain is central sensitization, which is an activity-dependent increase in the excitability of spinal neurons . Central sensitization has been shown to depend on the activation of dorsal hornNmethyl-D aspartate (NMDA) receptors by excitatory amino acid transmitters such as aspartate and glutamate. NMDA receptor antagonists prevent central sensitization induced by peripheral nociceptive stimuli by blocking dorsal horn NMDA receptor activation. Magnesium (Mg 2+) is a non-competitive N-methyl-Daspartate (NMDA) receptor antagonist that blocks ion channels in a voltage dependent fashion. Koining reported that intravenous magnesium administration led to significant reduction in fentanyl consumption in peri and post-operative periods. Studies have evaluated use of magnesium intrathecally and shown to prolong the action of subarachnoid anaesthesia [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. However, most of these studies used an opioid along with magnesium, which could have contributed to the prolongation of blockade after subarachnoid block [6-13], Magnesium alone with LA in a dose of 50 mg and maximum upto 100 mg has been used in a few studies [14][15][16][17][18][19]. Although the results of adding MgSO 4 50 mg to IT bupivacaine are conflicting, the effect of increasing the dose of additional MgSO 4 has not been fully investigated. We used a dose of about 0.7mg/ kg (50 mg) to ≤ 1mg/kg (75 mg) of intrathecal magnesium and found similar results. The primary outcome was the duration of spinal anaesthesia, beginning of sensory and motor block, time to maximal sensory block, and duration of sensory and motor block. The secondary outcomes included hemodynamic variations and post-operative analgesic requirements . MATeRIAlS AND MeThODSWe conducted a randomized double blind study on 90 patients of either sex, belonging to ASA physical status I and II scheduled for orthopaedi...

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“…ephedrine, 10 mg, was given repeatedly [22]. If HR was < 50 beats/ min, 0.6 mg of atropine sulphate was administered intravenously.…”

Section: Discussionmentioning

confidence: 99%

Comparative Efficacy of Two Different Dosages of Intrathecal Magnesium Sulphate Supplementation in Subarachnoid Block

Kathuria

Luthra

Gupta

et al. 2014

JCDR

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“…[1] Klohr et al [1] found across 63 publi cations that the incidence of spinal hypotension was 27% when defined as a systolic blood pressure (SBP) <70% of baseline, but that it increased to 39% using an SBP of <75% of baseline. Up to 80% of spinal anaesthetics in obstetrics require the use of a vasopressor to treat hypotension.…”

Section: Incidence and Definitionmentioning

confidence: 99%

“…Autonomic indices such as heart rate variability have also shown promise, [12] but have yet to be translated into a practical clinical tool. Given the high incidence of hypotension, [1,9] research in this area should focus on predicting which patients will have severe hypotension, where outcomes relating to maternal and fetal safety are more likely to be affected. We need simple clinical parameters that identify high risk patients and can be coupled to preventive strategies or earlier referral to specialist centres.…”

Section: Prediction Of Obstetric Spinal Hypotensionmentioning

confidence: 99%

Recipes for obstetric spinal hypotension: The clinical context counts

2016

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Hypotension following obstetric spinal anaesthesia remains a common and important problem. While recent research advances have brought us closer to the perfect recipe for the obstetric spinal anaesthetic, these advances have not been translated into practical guidelines able to reduce the unacceptable number of fatalities that occur in environments where resources are limited. In South Africa, more than half of anaesthetic deaths are still related to spinal hypotension. A gap exists between the 'perfect recipe' , developed from a clinical context rooted in resourcerich research environments, and its application and performance in realworld resourcepoor environments -conditions experienced by more than 75% of the world's population. This review attempts to define this knowledge gap and proposes a research agenda to address the deficiencies.

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“…Hypotension was defined as SAP less than 80% of baseline -the value accepted by most investigators. (32)(33)(34) In case of hypotension, a bolus of 100 mcg of intravenous phenylephrine was given as a rescue medication with no additional fluid. If there was concomitant bradycardia (heart rate < 50 beats/min), a bolus of 0.5 mg atropine was given.…”

Section: Methodsmentioning

confidence: 99%

Comparison of haemodynamic parameters between the high and low spinal block in young healthy patients

Poredoš¹,

Novak-Jankovič²

2017

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Background. For some surgical procedures a higher sensory block is needed. However, it is complicated by a higher incidence of hypotension, more bradycardia and nausea and a higher use of vasoactive drugs. In elderly and obstetric population complications have been attributed to the decrease in cardiac output and systemic vascular resistance, especially in a high block (above Th6). The aim of our study was to find the incidence of hypotension and bradycardia after a spinal anaesthesia in young, healthy patients. As young patients compensate more, we aimed to find the difference in haemodynamic variables between the group with a high and the group with a low spinal block and the underlying mechanisms of hypotension. Methods. In a prospective, randomized study 44 American Society of Anaesthesiologists (ASA) 1 patients scheduled for knee arthroscopy under spinal anaesthesia were randomly distributed to a high (group H) and a low (group L) spinal block group. In a group H patients were placed into horizontal, whereas in a group L in 15-degree anti-Trendelenburg position immediately after the spinal block. Haemodynamic parameters were measured continuously noninvasively from 10 min before to 25 min after the spinal block using the CNAPTM device with the LiDCORapid monitor. Results. The differences in haemodynamic parameters between the groups were not statistically significant at all measured times despite a significant difference in the spinal block level (18.5 vs 13.3 dermatomes above S5, p<0.001) and a significant difference in haemodynamic variables

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Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients

Cited by 216 publications

References 70 publications

Comparative Efficacy of Two Different Dosages of Intrathecal Magnesium Sulphate Supplementation in Subarachnoid Block

Comparative Efficacy of Two Different Dosages of Intrathecal Magnesium Sulphate Supplementation in Subarachnoid Block

Recipes for obstetric spinal hypotension: The clinical context counts

Comparison of haemodynamic parameters between the high and low spinal block in young healthy patients

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