Onset Of Spinal Anesthesia Research Articles

Impaired glucose utilization in the brain of patients with delirium following hip fracture.

Alterations in brain energy metabolism have long been proposed as one of several neurobiological processes contributing to delirium. This is supported by previous findings of altered CSF lactate and neuron-specific enolase concentrations and decreased glucose uptake on brain-PET in patients with delirium. Despite this, there are limited data on metabolic alterations found in CSF samples, and targeted metabolic profiling of CSF metabolites involved in energy metabolism has not been performed. The aim of the study was to investigate whether metabolites related to energy metabolism in the serum and CSF of patients with hip fracture are associated with delirium. The study cohort included 406 patients with a mean age of 81 years (standard deviation 10 years), acutely admitted to hospital for surgical repair of a hip fracture. Delirium was assessed daily until the fifth postoperative day. CSF was collected from all 406 participants at the onset of spinal anaesthesia, and serum samples were drawn concurrently from 213 participants. Glucose and lactate in CSF were measured using amperometry, whereas plasma glucose was measured in the clinical laboratory using enzymatic photometry. Serum and CSF concentrations of the branched-chain amino acids, 3-hydroxyisobutyric acid, acetoacetate and β-hydroxybutyrate were measured using gas chromatography-tandem mass spectrometry (GC-MS/MS). In total, 224 (55%) patients developed delirium pre- or postoperatively. Ketone body concentrations (acetoacetate, β-hydroxybutyrate) and branched-chain amino acids were significantly elevated in the CSF but not in serum among patients with delirium, despite no group differences in glucose concentrations. The level of 3-hydroxyisobutyric acid was significantly elevated in both CSF and serum. An elevation of CSF lactate during delirium was explained by age and comorbidity. Our data suggest that altered glucose utilization and a shift to ketone body metabolism occurs in the brain during delirium.

Colloid Preload versus Crystalloid Co-Load in the Setting of Norepinephrine Infusion during Cesarean Section: Time and Type of Administered Fluids Do Not Matter.

Background and Goal of Study: Spinal anesthesia for cesarean section is frequently associated with a high incidence of hypotension, which may bring about untoward effects for both the mother and fetus. Recently, norepinephrine has emerged as a promising alternative in maintaining blood pressure in the obstetric setting. Fluid administration is another technique still widely used to prevent maternal hypotension. The optimal fluid strategy to prevent maternal hypotension has not been elucidated yet. It has been recently suggested that the main strategy in the prevention and management of hypotension should be the combination of vasoconstrictive medications and fluid administration. The aim of this randomized study was to compare the incidence of maternal hypotension in parturients receiving either colloid preload or crystalloid co-load in the setting of prophylactic norepinephrine infusion during elective cesarean section under combined spinal-epidural anesthesia. Materials and Methods: After ethics committee approval, 102 parturients with full-term singleton pregnancies were randomly allocated to either 6% hydroxyethyl starch 130/0.4 5 mL/kg before the onset of spinal anesthesia (colloid preload group) or Ringer's lactate solution 10 mL/kg concurrent with the subarachnoid injection (crystalloid co-load group). In both groups, norepinephrine 4 μg/min starting simultaneously with the administration of the subarachnoid solution was also administered. The primary outcome of the study was the incidence of maternal hypotension, defined as systolic arterial pressure (SAP) <80% of baseline. The incidence of severe hypotension (SAP < 80 mmHg), total dose of vasoconstrictive agents administered, as well as the acid-base status and Apgar score of the neonate and any incidence of maternal side effects were also recorded. Results: Data analysis was performed on 100 parturients: 51 in the colloid preload group and 49 in the crystalloid co-load group. No significant differences were demonstrated between the colloid preload group and the crystalloid co-load group in the incidence of hypotension (13.7% vs. 16.3%, p = 0.933) or the incidence of severe hypotension (0% vs. 4%, p = 0.238). The median (range) ephedrine dose was 0 (0-15) mg in the colloid preload group and 0 (0-10) mg in the crystalloid co-load group (p = 0.807). The incidence of bradycardia, reactive hypertension, requirement for modification of vasopressor infusion, time to the first occurrence of hypotension, and maternal hemodynamics did not differ between the two groups. There were no significant differences in other maternal side effects or neonatal outcomes between groups. Conclusions: The incidence of hypotension with a norepinephrine preventive infusion is low and comparable with both colloid preload and crystalloid co-load. Both fluid-loading techniques are appropriate in women undergoing cesarean delivery. It appears that the optimal regimen for prevention of maternal hypotension is a combined strategy of a prophylactic vasopressor such as norepinephrine and fluids.

Comparison of Intravenous Ketamine with Intrathecal Meperidine in Prevention of Post-anesthetic Shivering after Spinal Anesthesia for Lower Limb Orthopedic Surgeries: A Double-blind Randomized Clinical Trial.

Post-anesthetic shivering is one of the most common complications after anesthesia. Ketamine has been considered to be an effective treatment for post-anesthetic shivering, but the evidence for its therapeutic benefit after spinal anesthesia is limited. The aim of this study was to compare the effects of intravenous ketamine with intrathecal meperidine in the prevention of post-anesthetic shivering after spinal anesthesia for lower limb orthopedic surgeries. In a double-blind randomized parallel-group clinical trial, a total of 150 patients scheduled for lower limb orthopedic surgeries under spinal anesthesia were selected and randomly divided into three equally sized groups of intravenous ketamine (0.5 mg/kg), intrathecal meperidine (0.2mg/kg) or intravenous normal saline (as placebo). The intensity of shivering in patients were evaluated during surgery and after transfer into the post anesthesia care unit. Also, changes in patients' drowsiness, nausea, vomiting, pruritus, mean arterial pressure, heart rate, and arterial oxygen saturation (SPO2) during surgery and until the end of anesthesia were evaluated. In all times of evaluation (20, 60, 80, 100 and 120 minutes after onset of spinal anesthesia) patients in control group showed a greater intensity of shivering compared to other groups. However, patients who received intrathecal meperidine experienced significantly lower intensity of post anesthetic shivering (p<0.05). The results showed a significant mean arterial pressure and heart rates differences between the three groups, only on 20 and 60 minutes after initiation of spinal anesthesia. The incidence of nausea, vomiting, and pruritus was not significantly different in all three groups, although all patients who received ketamine experienced drowsiness after surgery (p<0.001). The results of the present study showed that, although both intrathecal meperidine and intravenous ketamine could effectively prevent postoperative shivering after spinal anesthesia in lower limb orthopedic surgeries, intrathecal meperidine was associated with more efficacy benefits and a lower frequency of side effects such as post-anesthesia drowsiness.

Spinal anesthesia-induced hypotension is caused by a decrease in stroke volume in elderly patients.

BackgroundHypotension is common during spinal anesthesia (SA) and is caused by a decrease in systemic vascular resistance (SVR) and/or cardiac output (CO). The effect of the dose of bupivacaine administered intrathecally on the changes in CO in elderly patients is largely unknown. This study investigated the hemodynamic effect of SA in elderly patients by studying the effect of two different dosages of intrathecal bupivacaine.MethodsThis prospective cohort study included 64 patients aged >65 years scheduled for procedures under SA; the patients received either 15 mg bupivacaine (the medium dose [MD] group) or 10 mg bupivacaine and 5 μg sufentanil (the low dose [LD] group). Blood pressure and CO were monitored throughout the procedure using Nexfin™, a noninvasive continuous monitoring device using a finger cuff.ResultsThirty-three patients received MD and 31 received LD and there was no mean difference in baseline hemodynamics between the groups. On an average, the CO decreased 11.6% in the MD group and 10.0 % in the LD group. There was no significant change in SVR. Incidence of a clinically relevant decrease in stroke volume (SV) (>15% from baseline) was 67% in the MD and 45% in the LD groups (P<0.05).ConclusionCO and blood pressure decreased significantly after the onset of SA in elderly patients. This is mainly caused by a decrease in SV and not by a decrease in SVR. There was no difference in CO and blood pressure change between dosages of 10 or 15 mg bupivacaine.

Cerebrospinal fluid levels of neopterin are elevated in delirium after hip fracture.

BackgroundThe inflammatory cell product neopterin is elevated in serum before and during delirium. This suggests a role for disordered cell-mediated immunity or oxidative stress. Cerebrospinal fluid (CSF) neopterin levels reflect brain neopterin levels more closely than serum levels. Here we hypothesized that CSF neopterin levels would be higher in delirium.MethodsIn this prospective cohort study, 139 elderly patients with acute hip fracture were recruited in Oslo and Edinburgh. Delirium was diagnosed with the confusion assessment method performed daily pre-operatively and on the first 5 days post-operatively. Paired CSF and blood samples were collected at the onset of spinal anaesthesia. Neopterin levels were measured using high-performance liquid chromatography.ResultsSixty-four (46 %) of 139 hip fracture patients developed delirium perioperatively. CSF neopterin levels were higher in delirium compared to controls (median 29.6 vs 24.7 nmol/mL, p = 0.003), with highest levels in patients who developed delirium post-operatively. Serum neopterin levels were also higher in delirium (median 37.0 vs 27.1 nmol/mL, p = 0.003). CSF neopterin remained significantly associated with delirium after controlling for relevant risk factors. Higher neopterin levels were associated with poorer outcomes (death or new institutionalization) 1 year after surgery (p = 0.02 for CSF and p = 0.03 for serum).ConclusionsThis study is the first to examine neopterin in CSF from patients with delirium. Our findings suggest potential roles for activation of cell-mediated immune responses or oxidative stress in the delirium process. High levels of serum or CSF neopterin in hip fracture patients may also be useful in predicting poor outcomes.

Associations Between Delirium and Preoperative Cerebrospinal Fluid C-Reactive Protein, Interleukin-6, and Interleukin-6 Receptor in Individuals with Acute Hip Fracture.

To examine whether delirium in individuals with hip fracture is associated with high C-reactive protein (CRP), interleukin-6 (IL-6), and soluble IL-6 receptor (sIL-6R) levels in the cerebrospinal fluid (CSF). Prospective cohort study. Two university hospitals in Oslo, Norway, and Edinburgh, United Kingdom. Individuals admitted with acute hip fracture (N = 151). Participants were assessed for delirium pre- and postoperatively using the Confusion Assessment Method. Prefracture cognitive impairment was detected using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Serum was collected preoperatively and CSF just before the onset of spinal anesthesia. Cytokine levels in serum and CSF samples were determined using an enzyme-linked immunosorbent assay. Student t-tests or Mann-Whitney U-tests were used for between-group comparisons. Spearman rho was used for correlations. Sixty participants had prior cognitive impairment (IQCODE score ≥3.44). Delirium was diagnosed in 46 participants (77%) with prior cognitive impairment and 25 (29%) without. In participants without prior cognitive impairment, CSF CRP levels were higher in participants with delirium (median 0.05 μg/mL, interquartile range (IQR) 0.02-0.12 μg/mL) than in those without delirium (median 0.01 μg/mL, IQR 0.00-0.06 μg/mL) (P = .01); there were no differences in participants with prior cognitive impairment. In secondary analyses, in participants with prior cognitive impairment, the concentration of CSF sIL-6R was higher in those participants who developed delirium than in the other subgroups, but this difference was not statistically significant. Serum levels of CRP, IL-6, and sIL-6R were not different according to delirium in participants with or without prefracture cognitive impairment. High CSF levels of CRP and sIL-6R may be associated with delirium. Different pathophysiological mechanisms may operate in different subgroups, notably in relation to the presence of prior cognitive impairment.

Blood-Cerebrospinal Fluid Barrier Integrity in Delirium Determined by Q-Albumin

Background/Aims: Delirium is a common and serious complication in hospitalised patients and its pathophysiology is incompletely understood. We aimed to examine whether blood-cerebrospinal fluid barrier dysfunction, as measured by Q-albumin (the ratio of cerebrospinal fluid albumin to serum albumin), was associated with delirium. Methods: In this prospective cohort study of hip fracture patients from Oslo University Hospital, Norway, serum was collected preoperatively and cerebrospinal fluid just before the onset of spinal anaesthesia. Albumin levels in serum and cerebrospinal fluid were analysed consecutively, and Q-albumin was calculated using the formula [cerebrospinal fluid albumin (mg/dl) × 1,000]/[serum albumin (mg/dl)]. Q-albumin >10.2 was used as the cut-off for blood-cerebrospinal fluid barrier dysfunction. Patients were assessed daily for delirium using the Confusion Assessment Method. Results: Out of 120 patients, 69 had delirium, 22 had subsyndromal delirium, and 29 were free from delirium. The majority of patients, i.e. 106 (88%), had intact blood-cerebrospinal fluid barrier integrity, but all 14 patients with blood-cerebrospinal barrier dysfunction had delirium (n = 11) or subsyndromal delirium (n = 3). Conclusions: The results suggest that blood-cerebrospinal fluid barrier dysfunction may be relevant for delirium pathophysiology when it occurs. However, the low prevalence (16% of delirium patients) indicates that this is not a prerequisite for the development of delirium.

Intravenous low-dose ketamine injection versus dexmedetomidine infusion for prevention of intraoperative shivering during spinal anesthesia

Background Shivering is considered one of the most common adverse effects that occur during spinal anesthesia. Besides causing patient discomfort, shivering also interferes with patient monitoring and increases tissue oxygen demand. The present study was carried out to compare the effectiveness of intravenous low-dose ketamine (0.25 mg/kg) and dexmedetomidine intravenous infusion in prevention of shivering during spinal anesthesia. Materials and methods Sixty patients of both sexes were included in this prospective randomized-controlled study. Patients were divided randomly into two groups of 30 patients each. Group K (30 patients) received low-dose ketamine (0.25 mg/kg) and group D (30 patients) received dexmedetomidine infusion. The primary outcome measure of this study was intraoperative shivering. The secondary outcome measures were hemodynamic changes, sedation scores, and postoperative side effects. Results Patients in group D had a lower incidence of postspinal anesthesia shivering compared with patients in group K. In all, 13.33% of group K patients had grade 3 shivering in comparison with only 3.33% of patients in group D 10 min after the onset of spinal anesthesia (P=0.031). Deeper sedation was observed in group D patients as 36.67% of group D patients had grade 4 sedation compared with 23.33% of patients in group K after 10 min (P=0.048). Conclusion Dexmedetomidine infusion is more effective as an antishivering and sedating agent than low-dose ketamine injection in patients receiving spinal anesthesia.

Intravenous granisetron attenuates hypotension during spinal anesthesia in cesarean delivery: A double-blind, prospective randomized controlled study.

Background and Aims:This study was conducted to determine the effectiveness of intravenous (IV) granisetron in the prevention of hypotension and bradycardia during spinal anesthesia in cesarean delivery.Material and Methods:A total of 200 parturients scheduled for elective cesarean section were included in this study. They were randomly divided into two groups. Group I was given 1 mg granisetron diluted in 10 ml normal saline slowly IV, 5 min before spinal anesthesia. Group II was given 10 ml of normal saline, 5 min before spinal anesthesia. Mean arterial blood pressure and heart rate (HR) were recorded every 3 min until the end of surgery (for 45 min). The total consumption of vasopressors and atropine were recorded. Apgar scores at 1 and 5 min were also assessed.Results:Serial mean arterial blood pressure and HR values for 45 min after onset of spinal anesthesia were decreased significantly in group II, P < 0.0001. The incidence of hypotension after spinal anesthesia was 64% in group II and 3% in group I (P < 0.0001). The total doses of ephedrine (4.07 ± 3.87 mg vs 10.7 ± 8.9 mg, P < 0.0001), phenylephrine (0.0 microg vs 23.2 ± 55.1 microg, P < 0.0001), and atropine (0.0 mg vs 0.35 ± 0.49 mg P < 0.0001) consumed in both the groups respectively, were significantly less in group I versus group II.Conclusion:Premedication with 1 mg IV granisetron before spinal anesthesia in an elective cesarean section significantly reduces hypotension, bradycardia and vasopressors usage.

Anticholinergic Activity in Cerebrospinal Fluid and Serum in Individuals with Hip Fracture with and without Delirium

To examine whether anticholinergic activity (AA) in cerebrospinal fluid (CSF) and serum is associated with risk of delirium in individuals with hip fracture. Prospective cohort study. Two university hospitals in Oslo, Norway, and Edinburgh, UK. Individuals admitted with acute hip fracture (N = 151). Participants were assessed daily for delirium using the Confusion Assessment Method (preoperatively and postoperative days 1-5 (all) or until discharge (participants with delirium)). Prefracture cognitive function was assessed using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Serum was collected preoperatively and CSF at the onset of spinal anesthesia. AA in serum (SAA) and CSF samples was determined according to a muscarinic radio receptor bioassay. The association between AA measures and delirium was evaluated using logistic multivariate analyses. Fifty-two (54%) of the participants in Oslo and 20 (39%) in Edinburgh developed delirium. There was no statistically significant difference in AA between participants with and without delirium in Oslo (serum: 7.02 vs 6.08 pmol/mL, P = .54; CSF: 0.39 vs 0.48 pmol/mL, P = .26) or in Edinburgh (serum: 1.35 vs 1.62 pmol/mL, P = .76; CSF: 0.36 vs 0.31 pmol/mL, P = .93). Nor was there any difference in SAA (Oslo, P = .74; Edinburgh, P = .51) or CSF AA (Oslo, P = .21; Edinburgh, P = .93) when participants were subdivided into prevalent, incident, subsyndromal, and never delirium. Stratifying participants according to prefracture cognitive status (IQCODE) gave the same results. This is the first study of AA in CSF of individuals with and without delirium. The study does not support the hypothesis that central (CSF) or peripheral (serum) AA is an important mechanism of delirium in individuals with hip fracture.

Can the passive leg raise test predict spinal hypotension during cesarean delivery? An observational pilot study

BackgroundIt was hypothesized that patients who are preload dependent, as demonstrated by a >12% increase in cardiac output in response to a passive leg raise test, would be more likely to exhibit hypotension during spinal anesthesia for cesarean delivery. MethodsCardiac output response to the passive leg raise test was measured in 40 women before spinal anesthesia with a noninvasive, continuous cardiac output monitor (NICOM®). Patients were divided into two groups based on their performance on the passive leg raise test; those who increased cardiac output >12% following passive leg raise test were considered fluid responsive. NICOM® hemodynamic values were collected from the onset of spinal anesthesia until 10min after delivery of the fetus. The incidence of hypotension, defined as mean arterial blood pressure <70% of the patient’s baseline value was compared between the two groups. Vasopressor use, umbilical cord blood gases and Apgar scores were also compared between the groups. ResultsNine patients were fluid responsive and 31 were fluid non-responsive. The groups had similar demographics and baseline hemodynamic parameters. No significant differences were seen between the groups in the incidence of spinal hypotension, vasopressor use, or neonatal outcome. At the time of delivery, fluid responsive patients had larger cardiac outputs compared to fluid non-responsive patients. ConclusionsIn this pilot study, non-invasive assessment of the hemodynamic response to a volume load was not predictive of hypotension or vasopressor use during cesarean delivery under spinal anesthesia. Fluid responsiveness was related to hemodynamic responses at delivery.

Cerebrospinal Fluid β‐Amyloid and Tau Are Not Associated with Risk of Delirium: A Prospective Cohort Study in Older Adults with Hip Fracture

To examine the association between cerebrospinal fluid (CSF) β-amyloid (Aβ1-42), tau, and hyperphosphorylated tau (Ptau) and risk of delirium in older adults with hip fracture. Prospective cohort study. University-affiliated general hospital in Alkmaar, the Netherlands. Seventy-six participants aged 75 and older admitted for surgical repair of acute hip fracture. Presurgical baseline screening and assessment included the Informant Questionnaire on Cognitive Decline-short form (IQCODE-N), Mini-Mental State Examination, standardized Snellen test for visual impairment, Geriatric Depression Scale, Barthel Index (BI), and Lawton Instrumental Activity of Daily Living (IADL) scale. The number of medical comorbidities and medications at home, American Society of Anesthesiologists score, and Acute Physiology and Chronic Health Evaluation II score were determined according to chart review. Delirium was diagnosed using the Confusion Assessment Method. CSF was collected at the onset of spinal anesthesia. Postoperative delirium occurred in 30 (39.5%) participants. Participants with delirium were older, showed more signs of cognitive decline, were more dependent at home in activity of daily living and IADL functioning, and used more medications before admission. Preoperative CSF Aβ1-42, tau, and Ptau levels were not significantly different in participants who did and did not develop delirium during subsequent hospitalization. In contrast, prefracture cognitive decline (IQCODE-N) was significantly related to delirium (odds ratio=9.43, 95% confidence interval=2.45-36.31). Cognitive impairment predisposes to delirium, but in this study, postoperative delirium was not associated with baseline CSF Aβ1-42, tau, and Ptau levels. These findings suggest that CSF markers for plaque and tangle formation are not strongly associated with delirium risk in older adults with hip fracture.

CEREBROSPINAL FLUID INTERLEUKIN-8 LEVELS ARE HIGHER IN PEOPLE WITH HIP FRACTURE WITH PERIOPERATIVE DELIRIUM THAN IN CONTROLS

CEREBROSPINAL FLUID INTERLEUKIN-8 LEVELS ARE HIGHER IN PEOPLE WITH HIP FRACTURE WITH PERIOPERATIVE DELIRIUM THAN IN CONTROLS

Pulmonary effects of bupivacaine, ropivacaine, and levobupivacaine in parturients undergoing spinal anaesthesia for elective caesarean delivery: A randomised controlled study

Background Spinal anaesthesia is the method of choice for elective caesarean delivery, but has been reported to worsen dynamic pulmonary function when using bupivacaine. Similar investigations are lacking for ropivacaine and levobupivacaine. We have therefore compared the pulmonary effects of intrathecal bupivacaine, ropivacaine and levobupivacaine used for caesarean delivery. Methods Forced vital capacity, forced expiratory volume in the first second, and peak expiratory flow rate were measured in 48 parturients before and after onset of spinal anaesthesia using either 0.5% bupivacaine 10 mg, 1% ropivacaine 20 mg, or 0.5% levobupivacaine 10 mg. Apgar scores and umbilical arterial pH were recorded. Results The final level of sensory blockade was not different between groups. Forced vital capacity was significantly decreased with bupivacaine (3.6 ± 0.5 L to 3.5 ± 0.4 L, P < 0.05) and ropivacaine (3.2 ± 0.4 L to 3.1 ± 0.5 L, P < 0.05), but not with levobupivacaine (3.6 ± 0.5 L to 3.4 ± 0.6 L). Forced expiratory volume during the first second was not decreased in any group. Peak expiratory flow rate was significantly decreased with ropivacaine (5.5 ± 1.5 L/s to 5.0 ± 1.1 L/s, P < 0.05) and levobupivacaine (from 6.0 ± 1.1 L/s to 5.2 ± 0.9 L/s, P < 0.01). Neonatal vital parameters did not differ between the three groups. Conclusions Decreases in maternal pulmonary function tests were similar following spinal anaesthesia with bupivacaine, ropivacaine, or levobupivacaine for caesarean delivery. The clinical maternal and neonatal effects of these alterations appeared negligible.

Maternal haemodynamics at elective caesarean section: a randomised comparison of oxytocin 5-unit bolus and placebo infusion with oxytocin 5-unit bolus and 30-unit infusion

Background Rapid intravenous injection of oxytocin is associated with marked hypotension secondary to decreased venous return. Reductions in dose and rate of bolus administration have reduced the incidence of cardiovascular side effects, but no study has yet investigated cardiovascular stability when oxytocin is infused for several hours after delivery. This study compared maternal haemodynamics during a 4-h 30-unit oxytocin infusion and during a placebo infusion following caesarean section. Methods Women booked for elective caesarean section were randomised to receive either oxytocin 5-unit bolus and placebo infusion or oxytocin 5-unit bolus and oxytocin 30-unit infusion. Before, during and for 4 h after surgery electrocardiogram, oxygen saturation, systolic and diastolic pressure and heart rate were monitored non-invasively and cardiac index (CI), left ventricular work index (LVWi) and systemic vascular resistance index (SVRi) by thoracic bioimpedance. Results A total of 74 women agreed to haemodynamic measurements. Heart rate, systolic and diastolic pressure, CI, LCWi and SVRi all fell following the onset of spinal anaesthesia, and, with the exception of SVRi, continued to decrease throughout surgery. After delivery of the baby, slow injection of oxytocin 5 units was associated with a temporary rise in CI, LCWi and heart rate, a decrease in SVRi and no change in systolic or diastolic pressure. Thereafter, haemodynamic measures returned to normal over 60 min with no adverse effects apparent from the additional oxytocin infusion. Conclusions An additional oxytocin infusion at elective caesarean section did not adversely affect maternal haemodynamics either during or after surgery.

Cerebrospinal fluid cortisol levels are higher in patients with delirium versus controls

BackgroundHigh plasma cortisol levels can cause acute cognitive and neuropsychiatric dysfunction, and have been linked with delirium. CSF cortisol levels more closely reflect brain exposure to cortisol, but there are no studies of CSF cortisol levels in delirium. In this pilot study we acquired CSF specimens at the onset of spinal anaesthesia in patients undergoing hip fracture surgery, and compared CSF and plasma cortisol levels in delirium cases versus controls.FindingsDelirium assessments were performed the evening before or on the morning of operation with a standard battery comprising cognitive tests, mental status assessments and the Confusion Assessment Method. CSF and plasma samples were obtained at the onset of the operation and cortisol levels measured. Twenty patients (15 female, 5 male) aged 62 - 93 years were studied. Seven patients were diagnosed with delirium. The mean ages of cases (81.4 (SD 7.2)) and controls (80.5 (SD 8.7)) were not significantly different (p = 0.88). The median (interquartile range) CSF cortisol levels were significantly higher in cases (63.9 (40.4-102.1) nmol/L) than controls (31.4 (21.7-43.3) nmol/L; Mann-Whitney U, p = 0.029). The median (interquartile range) of plasma cortisol was also significantly higher in cases (968.8 (886.2-1394.4) nmol/L, than controls (809.4 (544.0-986.4) nmol/L; Mann Whitney U, p = 0.036).ConclusionsThese findings support an association between higher CSF cortisol levels and delirium. This extends previous findings linking higher plasma cortisol and delirium, and suggests that more definitive studies of the relationship between cortisol levels and delirium are now required.

Upper and lower extremity regional haemoglobin oxygen saturation in spinal anaesthesia

Differential distribution of blood flow to blocked or unblocked areas in regional anesthesia may occur due to the differential vasodilatation following sympathetic efferent nerve blockade. Laser doppler flowmetry and thermography [1, 2] have been used to detect this, successfully predicting the effects of regional anaesthesia, though they are not always available in the operating theatre. Well maintained blood pressure during spinal anaesthesia may, secondary to vasoconstriction in the unblocked area, compensate for the vasodilatation of spinal anaesthesia. Vasodilatation effects measured simultaneously in blocked and unblocked areas have not been reported. Near-infrared spectroscopy (NIRS) gives real-time regional haemoglobin oxygen saturation (rSO2) [3, 4]. In this pilot study, we measured rSO2 simultaneously, above and below the spinal anaesthetic levels during block onset. After approval of the institutional human investigation committee (no. 200808010R), and with informed consent, 20 consecutive patients (29–79 years) without a history of neurological or vascular disorder, having lower extremity operations under spinal anaesthesia were recruited to the study. NIRS (INVOS Cerebral Oximeter Model 5100B; Somanetics, Troy, MI, USA) with two adhesive patches was used to monitor rSO2. One patch was applied over the biceps brachii muscle, (the body part above the anaesthetic level), and the other patch was applied over the medial side of the gastrocnemius muscle of the non-surgical leg, (the body part below the anaesthetic level). In both extremities, rSO2 was monitored continuously and recorded every minute from before intrathecal bupivacaine injection until 15 min after injection. Isobaric bupivacaine 0.5% 12–15 mg was injected intrathecally and the level of anaesthesia was examined 10 min later by loss of cold sensation to alcohol swab by an anaesthetist not involved in the study. Statistical analysis used Sigmastat v.3 by spss. Data are mean (SD). Analysis used two-way ANOVA and a p value < 0.05 was considered significant. Multiple comparisons were used to differentiate between groups. Anaesthesia between T6-T11 was achieved and blood pressure was maintained within 15% of baseline. Baseline arm and calf rSO2 were 70.8 (12.8) and 65.1 (10.4) %, respectively. As shown in Fig. 5, rSO2 in the calf increased soon after induction of spinal anesthesia (p < 0.001). rSO2 in the arm did not decrease significantly. There was a statistically significant interaction between time and site (p = 0.016). Changes in regional haemoglobin oxygen saturation (rSO2) at upper and lower extremities as measured by near-infrared spectroscopy in spinal anesthesia. Data are mean (SE). Our results showed a divergence of rSO2 between unblocked and blocked body parts with the onset of spinal anaesthesia. The slight decrease of rSO2 in the upper limb may indicate mild vasoconstriction with onset of spinal anesthesia. NIRS may serve as a potential monitor for the onset of neuroaxial blockade predicting the success of the block. It may be potentially useful in patients with hearing or speech difficulties. The rSO2 detects haemoglobin oxygen saturation at a depth of 30 and 40 mm in tissue rather than skin oxygen saturation which has been found to be unreliable for detecting sympathetic block [5]. There are limitations to this work, firstly lower extremity rSO2 increased by < 5% in four out of 20 patients although spinal anaesthesia was adequate. Secondly, the lower extremity increase in rSO2 indicated onset of spinal anesthesia but not adequacy of surgical anesthesia. We suggest that detection of rSO2 over non-anaesthetised and anaesthetised body parts could be an alternative monitor for onset of neuroaxial blockade.

Is it possible to predict hypotension during onset of spinal anesthesia in elderly patients?

Study Objective To evaluate the sensitivity and specificity of various predictors of hypotension during onset of spinal anesthesia in elderly patients. Design Prospective study. Setting 32 ASA physical status I, II, and III patients, aged ≥60 years, scheduled for elective lower limb surgery with spinal anesthesia. Interventions Patients received spinal anesthesia with 10-17.5 mg of bupivacaine. No prophylactic ephedrine or fluid preloading was used. Measurements A 5-minute baseline was recorded and during onset of spinal anesthesia, hemodynamic changes were measured every 10 seconds from the radial artery pressure curve. Data collection ended when patients were ready for surgery, or if ephedrine was given to increase mean arterial pressure. Main Results 21 patients had hypotension. Baseline blood pressure variability low-frequency band power (BPV LF) >8 mmHg 2 and near-infrared spectroscopy (NIRS) reduction ≥5% had high sensitivity (0.73 and 0.90, respectively) and specificity (0.78 and 0.64, respectively), and were significantly associated with the development of hypotension. Conclusions Only NIRS and BPV LF could significantly predict hypotension among the elderly.

Biphasic cardiac output changes during onset of spinal anaesthesia in elderly patients

In most studies of cardiac output changes after spinal anaesthesia, the time-resolution is limited. The aim of this study was to demonstrate cardiac output changes with high time-resolution during onset of spinal anaesthesia in elderly patients. We investigated 32 patients aged 60 yr scheduled for elective lower limb surgery. Fourteen received concurrent cardiovascular medication. Cardiac output was measured every 10 s using a pulse wave algorithm derived from the radial artery pressure curve, after calibration with lithium chloride (LiDCOplus). Data collection ended when the patients were ready for surgery, or if ephedrine was given to raise the mean arterial pressure. Cardiac output increased initially reaching a maximum after a mean of 7 min. The average increase was 1.1 L min(-1) (P<0.0001). This occurred when mean arterial pressure was reduced 14 mmHg on average. At the end of data collection, cardiac output decreased 0.5 L min(-1) from baseline (P=0.02). Mean arterial pressure decreased progressively in all patients, and only minimal changes in heart rate were found. Using this high time-resolution method, we detected biphasic changes in cardiac output during onset of spinal anaesthesia. Initially, cardiac output increased. Subsequently, it was significantly reduced from baseline, although this decrease was of minor clinical importance.

Effect of preoperative amino acid infusion on thermoregulatory response during spinal anaesthesia

Intravenous amino acid infusion during general anaesthesia prevents decreases in core temperature resulting from increased energy expenditure and heat accumulation. We investigated whether such stimulation also occurs during spinal anaesthesia, which blocks sympathetic nervous activity. We examined the effect of i.v. amino acid infusion on changes in core temperature during spinal anaesthesia. Thirty-five patients were divided into two groups: an i.v. amino acid infusion group (4 kJ kg(-1) h(-1) starting 2 h before surgery); and a saline infusion group. Tympanic membrane core temperature, forearm-fingertip temperature gradient (an index of peripheral vasoconstriction) and mean skin temperature were measured for 90 min after the onset of spinal anaesthesia. Changes in mean arterial pressure and heart rate did not differ significantly between the groups during the study period. Mean final core temperature 90 min after induction of spinal anaesthesia was 35.8 (SEM 0.1) degrees C in the saline group and 36.6 (0.1) degrees C in the amino acid group (P<0.05). The increased level of oxygen consumption in the amino acid group compared with the saline group was preserved even after the onset of spinal anaesthesia. The thermal vasoconstriction threshold, defined as the tympanic membrane temperature that triggered a rapid increase in forearm-fingertip temperature gradient, was increased in the amino acid group [36.8 (0.1) degrees C] compared with the saline group [36.5 (0.1) degrees C] (P<0.05). Preoperative infusion of amino acids effectively prevents spinal anaesthesia-induced hypothermia by maintaining a higher metabolic rate and increasing the threshold core temperature for thermal vasoconstriction.