Prevention of Spinal Anesthesia-Induced Hypotension in the Elderly

Hemodynamic impact of ephedrine on hypotension during general anesthesia: a prospective cohort study on middle-aged and older patients

BACKGROUND

Ephedrine is a mixed α- and β-agonist vasopressor that is frequently used for the correction of hypotension during general anesthesia. β-responsiveness has been shown to decrease with age; therefore, this study aimed to determine whether aging would reduce the pressor effect of ephedrine on hypotension during general anesthesia.

METHODS

Seventy-five patients aged ≥ 45 years were included in this study, with 25 patients allocated to each of the three age groups: 45-64 years, 65-74 years, and ≥ 75 years. All patients received propofol, remifentanil, and rocuronium for the induction of general anesthesia, followed by desflurane and remifentanil. Cardiac output (CO) was estimated using esCCO technology. Ephedrine (0.1 mg/kg) was administered for the correction of hypotension. The primary and secondary outcome measures were changes in the mean arterial pressure (MAP) and CO, respectively, at 5 min after the administration of ephedrine.  RESULTS: The administration of ephedrine significantly increased MAP (p < 0.001, mean difference: 8.34 [95% confidence interval (CI), 5.95-10.75] mmHg) and CO (p < 0.001, mean difference: 7.43 [95% CI, 5.20-9.65] %) across all groups. However, analysis of variance revealed that the degree of elevation of MAP (F [2, 72] = 0.546, p = 0.581, η2 = 0.015 [95% CI, 0.000-0.089]) and CO (F [2, 72] = 2.023, p = 0.140, η2 = 0.053 [95% CI, 0.000-0.162]) did not differ significantly among the groups. Similarly, Spearman's rank correlation and multiple regression analysis revealed no significant relation between age and the changes in MAP or CO after the administration of ephedrine.

CONCLUSION

The administration of ephedrine significantly increased MAP and CO; however, no significant correlation with age was observed in patients aged > 45 years. These findings suggest that ephedrine is effective for the correction of hypotension during general anesthesia, even in elderly patients.

TRIAL REGISTRATION

UMIN-CTR (UMIN000045038; 02/08/2021).

Can Ultrasound-Guided Femoral Vein Measurements Predict Spinal Anesthesia-Induced Hypotension in Non-Obstetric Surgery? A Prospective Observational Study

Background and objectives: To investigate whether ultrasound (US)-guided femoral vein (FV) and inferior vena cava (IVC) measurements obtained before spinal anesthesia (SA) can be utilized to predict SA-induced hypotension (SAIH) and to identify risk factors associated with SAIH in patients undergoing non-obstetric surgery under SA. Methods: This was a prospective observational study conducted between November 2021 and April 2022. The study included 95 patients over the age of 18 with an American Society of Anesthesiologists (ASA) physical status score of 1 or 2. The maximum and minimum diameters of FV and IVC were measured under US guidance before SA initiation, and the collapsibility index values of FV and IVC were calculated. Patients with and without SAIH were compared. Results: SAIH was observed in 12 patients (12.6%). Patients with and without SAIH were similar in terms of age [58 (IQR: 19-70) vs. 48 (IQR: 21-71; p = 0.081) and sex (males comprised 63.9% of the SAIH and 75.0% of the non-SAIH groups) (p = 0.533). According to univariate analysis, no significant relationship was found between SAIH and any of the FV or IVC measurements. Multiple logistic regression analysis revealed that having an ASA class of 2 was the only independent risk factor for SAIH development (p = 0.014), after adjusting for age, sex, and all other relevant parameters. Conclusions: There is not enough evidence to accept the feasibility of utilizing US-guided FV or IVC measurements to screen for SAIH development in patients undergoing non-obstetric surgery under SA. For this, multicenter studies with more participants are needed.

The influence of the infusion of ephedrine and phenylephrine on the hemodynamic stability after subarachnoid anesthesia in senior adults - a controlled randomized trial

Background

We studied the influence of ephedrine or phenylephrine infusion administered immediately after spinal anesthesia (SA) on hemodynamics in elderly orthopedic patients.

Methods

A prospective, randomized, double-blind, placebo-controlled study.

After a subarachnoid injection of 15 mg of levobupivacaine, the participants received an infusion of either ephedrine 20 mg (E group), phenylephrine 250 mcg (P group) or saline (C group) within 30 min. We measured blood pressure, cardiac index (CI) and heart rate (HR) from 15 min before to 30 min after SA.

Results

Seventy patients were included in the final analysis. At the end of measurements, mean arterial pressure (MAP) decreased significantly after SA in comparison to the baseline value in the C group but was maintained in the P and E group, with no significant differences between the groups. CI decreased after SA in the C group, was maintained in the P group, and increased significantly in the E group with significant differences between the C and E group (p = 0.049) also between the P and E (p = 0.01) group at the end of measurements. HR decreased significantly after SA in the C and P group but was maintained in the E group, with significant differences between the P and E group (p = 0.033) at the end of measurements.

Conclusions

Hemodynamic changes after SA in elderly orthopedic patients can be prevented by an immediate infusion of phenylephrine or ephedrine. In addition to maintaining blood pressure, the ephedrine infusion also maintains HR and increases CI after SA.

Trial registration

ISRCTN registry with registration number ISRCTN44377602, retrospectively registered on 15 June 2017.

Is postspinal hypotension a sign of impaired cardiac performance in the elderly? An observational mechanistic study

Background

We have previously reported that stroke volume is reduced in a majority of elderly patients undergoing surgical repair of hip fracture before and after intrathecal injection of anaesthetic. We aimed to investigate these observations further in a prospective study of elderly patients undergoing elective hip or knee arthroplasty under spinal anaesthesia.

Methods

Patients ≥65 yr undergoing elective arthroplasty were monitored with LiDCOplus™ preoperatively (baseline), before and continuously for 45 min after spinal anaesthesia. Postspinal hypotension was defined as systolic blood pressure (bp) < 100 mm Hg or > 30% decrease from baseline. Associations between post-spinal hypotension and haemodynamic changes before (i.e. between baseline and before injection) spinal anaesthesia were analysed by logistic regression analysis.

Results

Twenty patients with a mean age of 74 (range 66-89) yr were included. Stroke volume index decreased by 14% (95% CI 9.3%-19%) before spinal anaesthesia. When patients were categorised according to post-spinal hypotension (Y/N) the patterns of haemodynamic changes differed. In the hypotensive patients, cardiac index progressively decreased whereas it increased initially in the non-hypotensive patients. Reduction of cardiac index from baseline before spinal anaesthesia was associated with increased risk of hypotension: OR 0.79 (95% CI 0.60, 0.91). The predictive value of reduced cardiac index was good (AUC under ROC curve 0.91).

Conclusions

A decrease in cardiac output from baseline before spinal anaesthesia and an inability to increase it after induction may be important features of postspinal hypotension in elderly patients.

Effect of hydroxyethyl starch on blood glucose levels

Background

Hydroxyethyl starch (HES), a commonly used resuscitation fluid, has the property to induce hyperglycemia as it contains large ethyl starch, which can be metabolized to produce glucose. We evaluated the effect of 6% HES-130 on the blood glucose levels in non-diabetic patients undergoing surgery under spinal anesthesia.

Methods

Patients scheduled to undergo elective lower limb surgery were enrolled. Fifty-eight patients were divided into two groups according to the type of the main intravascular fluid used before spinal anesthesia (Group LR: lactated Ringer's solution, n = 30 vs. Group HES: 6% hydroxyethyl starch 130/0.4, n = 28). Blood glucose levels were measured at the following time points: 0 (baseline), 20 min (T1), 1 h (T2), 2 h (T3), 4 h (T4), and 6 h (T6).

Results

Mean blood glucose levels at T5 in the LR group and T4, T5 in the HES group, increased significantly compared to baseline. There were no significant changes in the serial differences of mean blood glucose levels from baseline between the two groups.

Conclusions

Administration of 6% HES-130 increased blood glucose levels within the physiologic limits, but the degree of glucose increase was not greater than that caused by administration of lactated Ringer's solution. In conclusion, we did not find evidence that 6% HES-130 induces hyperglycemia in non-diabetic patients.

Prophylactic glycopyrrolate reduces hypotensive responses in elderly patients during spinal anesthesia: a randomized controlled trial

BACKGROUND

Hypotension during spinal anesthesia is a serious complication in elderly patients. We evaluated the effect of glycopyrrolate on hypotensive responses in elderly patients undergoing spinal anesthesia.

METHODS

Sixty-six patients older than 60 yr of age scheduled for elective surgery with spinal anesthesia were included in the study. They received either glycopyrrolate 0.2 mg (group G) or normal saline (group C) intramuscularly 15 min before spinal anesthesia. The following outcomes were evaluated after the induction of spinal anesthesia: the incidence of hypotension and bradycardia, the ephedrine requirement, mean arterial pressure, heart rate, and the incidence of nausea and vomiting.

RESULTS

Twenty-three of 33 (70.0%) patients in group C experienced hypotension compared with nine of 33 (27.3%) patients in group G (difference = 42.7%; 95% confidence interval [CI]: 18.4 to 60.2; P = 0.001). The median [interquartile range] amount of ephedrine required was 5 [0-15] mg in group C compared with 0 [0-5] mg in group G (difference = 5.0 mg; 95% CI: 2.7 to 7.3; P = 0.001). Nine (27.3%) patients in group C experienced nausea and vomiting compared with 2 (6.1%) in group G (difference = 21.2%; 95% CI: 3.0 to 38.7; P = 0.044). Three (9.1%) patients in group C experienced bradycardia compared with 1 (3.0%) patient in group G (difference = 6.1%; 95% CI: -7.6 to 20.8; P = 0.613).

CONCLUSION

Prophylactic intramuscular glycopyrrolate reduced the occurrence and severity of hypotensive responses, the requirement for ephedrine, and the incidence of nausea and vomiting in elderly patients undergoing spinal anesthesia. The trial was registered at the Clinical Research Information Service, Republic of Korea (KCT0000556).

Crystalloid and colloid preload for maintaining cardiac output in elderly patients undergoing total hip replacement under spinal anesthesia

The aim of the present study was to compare the effects of colloid and crystalloid preload on cardiac output (CO) and incidence of hypotension in elderly patients under spinal anesthesia (SA). A randomized, double-blinded study was conducted including 47 elderly patients undergoing scheduled total hip replacement (THR), who were randomized to three groups: the control group (C group, n = 15), crystalloid (RS group, n =16) and colloid group (HES group, n = 16). An intravenous preload of 8 mL/kg of either lactated Ringer's solution in the RS group or 6% hydroxyethyl starch in the HES group was infused within 20 min before SA induction, while no intravenous preload was given in the C group. There was a trend of decrease in CO and systolic blood pressure after SA with time in the C group. In the RS and HES groups, CO increased significantly after fluid preloading as compared with baseline (P < 0.01). Thereafter, CO remained higher than baseline until 30 min after SA in the HES group. The change of systolic blood pressure was similar to CO, but no significant difference from baseline was observed in each group. Hypotension occurred in 3 patients in the C group and one each in the RS and HES group, respectively (P = 0.362). Intravascular volume preload with colloid is more effective than crystalloid solution in maintaining CO, which may be improved the hemodynamic stability in elderly patients during SA.

Comparison Between the Effects of Ringer`s Lactate and Hydroxyethyl Starch on Hemodynamic Parameters After Spinal Anesthesia: A Randomized Clinical Trial

BACKGROUND

Hypotension during spinal anesthesia is common and can lead to severe injuries and even death. Administration of crystalloid fluids is advised to prevent occurrence of hypotension; however its effectiveness is still the matter of arguments.

OBJECTIVES

This study was designed to compare the effects of Ringer`s lactate and hydroxyethyl starch 6% on hemodynamic parameters after spinal anesthesia in patients undergoing orthopedic surgeries on lower limbs.

PATIENTS AND METHODS

This randomized clinical trial was performed in Rasoul Akram Hospital, Tehran, Iran. 60 patients undergoing elective femoral fracture surgeries with spinal anesthesia were included in this study. Fitted patients were randomly divided into two equal groups. After entrance to the operation room and before spinal anesthesia, patients' hemodynamic parameters including systolic blood pressure (SBP), cardiac output (CO), and cardiac index (CI) were evaluated using monitoring electro-velocimetry set. In both groups, spinal anesthesia was performed using needle no. 25 and 3 mL of marcaine 0.5% in the sterile situation. None of the treatment group was aware of investigated group during the study.

RESULTS

The baseline values of mentioned variables did not show a significant difference between two groups using t-test (P > 0.05). Also SBP, CI, and CO after intervention was not significantly different between two groups using t-test (P > 0.05).

CONCLUSIONS

The result of present study on patients undergoing femoral fracture surgeries who received Hetastarch or Ringer`s lactate solutions showed that Hetastarch was not significantly more effective in compensation of hypotension induced by spinal anesthesia.

The effect of the intravenous phenylephrine on the level of spinal anesthesia

Background

Spinal anesthesia causes hypotension and bradycardia due to sympathetic nerve block and it is difficult to predict the level of sensory block and the duration of blockade. Recent studies have reported that intravenous phenylephrine can reduce the rostral spread of spinal anesthesia in pregnant women. We think a phenylephrine infusion will be useful for maintaining the baseline blood pressure by reducing the rostral spread of spinal anesthesia during the elective surgery of non-obstetric patients.

Methods

Sixty patients who were undergoing urologic surgery were randomized into two groups: Group C (the control group without phenylephrine) and Group P (with the addition of phenylephrine). After a bolus infusion of 50 µg phenylephrine following the spinal injection, phenylephrine was continuously infused at the rate of 200 µg/hr. We compared the dermatomal spreads of spinal anesthesia, the hemodynamic parameters (blood pressure, heart rate) and the incidences of hypotension between the two groups.

Results

At 20 minutes, the level of the upper dermatome blocked against cold sensation was a median of T8 (interquartile range: T8-T10) for the phenylephrine group, as compared with T4 (interquartile range: T4-T6) for the control group (P < 0.001).

Conclusions

Intravenous phenylephrine can decrease the rostral spread of spinal anesthesia during urologic surgery.

Effect of 6% hydroxyethyl starch-450 and low molecular weight dextran on blood sugar levels during surgery under subarachnoid block: A prospective randomised study

Dextrans and hydroxyethyl starches produce significant levels of free glucose residues following metabolism. The following study was designed to compare 6% hydroxyethyl starch-450 with Dextran 40, both used as preloading fluids, for their potential to raise peri-operative blood glucose levels. After taking an informed consent, 180 non-diabetic adult patients, posted for elective surgery under spinal anaesthesia, were randomly divided into three groups, to receive Ringer’s Lactate 20 ml/kg (group 1), Dextran 40,10 ml/kg (group 2) and Hestar 6%-450, 10 ml/kg (group 3), over half an hour, prior to the subarachnoid block, as preloading fluid, and serial capillary blood glucose measurements were taken thereafter at regular intervals up to 240 minutes from the baseline reading. All the three preloading fluids, including Ringer’s Lactate used as control, were seen to significantly increase the capillary blood glucose levels intra-operatively (P < 0.05), but the rise with Dextran-40 was seen to be sustained and highly significant (P < 0.001). We thus conclude that, Dextran40 causes a sustained and significant rise in peri-operative blood glucose levels.

The effect of Trendelenburg position, lactated Ringer's solution and 6% hydroxyethyl starch solution on cardiac output after spinal anesthesia

BACKGROUND

The aim of our study was to evaluate the effects of Trendelenburg position, infusion of 6% hydroxyetyl starch solution or lactated Ringer's solution on changes in cardiac output (CO) after spinal anesthesia in patients older than 50 yr.

METHODS

Seventy patients scheduled for lower extremity orthopedic surgery under spinal anesthesia were allocated randomly to one of the three treatment groups. In the Trendelenburg group, the patients were placed in the Trendelenburg position immediately after the spinal block for 10 min. In the hydroxyethyl starch group and the lactated Ringer's group, the patients received an infusion of 500 mL of 6% hydroxyethyl starch solution or 1000 mL of lactated Ringer's solution over 20 min after the spinal block. CO was measured continuously from 15 min before until 30 min after spinal anesthesia using the impedance cardiography method and arterial blood pressure with an automated device. P < 0.05 was considered statistically significant.

RESULTS

The differences among treatment groups in CO were not statistically significant. Differences in the CO changes from baseline over time were significant. In the Trendelenburg group, CO did not change while the patient was in the Trendelenburg position. In the hydroxyethyl starch group, CO increased significantly after the block and remained significantly increased until the end of measurements. In the lactated Ringer's group, CO increased significantly 10 and 20 min after the block but, after stopping the infusion, CO started to decrease.

CONCLUSIONS

Our study demonstrated that a decrease in CO after spinal anesthesia is prevented by placing the patient in the Trendelenburg position, or infusion of either lactated Ringer's solution or 6% hydroxyetyl starch solution. Although the effects of the infusion of the lactated Ringer's solution are transient, the effects of the infusion of 6% hydroxyethyl starch solution are extended beyond the time the infusion.

Predicting hypotensive episodes during spinal anesthesia with the application of artificial neural networks

Hypotension is one of the most frequent adverse effects of spinal anesthesia. Several factors might be related to the occurrence of hypotension. Predictions of the hypotensive event, however, had been addressed by only a few authors using logistic regression (LR) models. Artificial neural networks (ANN) are pattern-recognition tools that can be used to detect complex patterns within data sets. The purpose of this study was to develop the ANN-based predictive model to identify patients with high risk of hypotension during spinal anesthesia. From September 2004 to December 2006, the anesthesia records of 1501 patients receiving surgery under spinal anesthesia were used to develop the ANN and LR models. By random selection 75% of data were used for training and the remaining 25% of data were used as test set for validating the predictive performance. Five senior anesthesiologists were asked to review the data of test set and to make predictions of hypotensive event during spinal anesthesia by clinical experience. The ANN model had a sensitivity of 75.9% and specificity of 76.0%. The LR model had a sensitivity of 68.1% and specificity of 73.5%. The area under receiver operating characteristic curves were 0.796 and 0.748. The ANN model performed significantly better than the LR model. The prediction of clinicians had the lowest sensitivity of 28.7%, 22.2%, 21.3%, 16.1%, and 36.1%, and specificity of 76.8%, 84.3%, 83.1%, 87.0%, and 64.0%. The computer-based predictive model should be useful in increasing vigilance in those patients most at risk for hypotension during spinal anesthesia, in allowing for patient-specific therapeutic intervention, or even in suggesting the use of alternative methods of anesthesia.

Spinal anesthesia using single injection small-dose bupivacaine versus continuous catheter injection techniques for surgical repair of hip fracture in elderly patients

Aging and disease may make elderly patients particularly susceptible to hypotension during spinal anesthesia. We compared the hemodynamic effect of continuous spinal anesthesia (CSA) and small dose single injection spinal anesthesia (SA) regarding the incidence of hypotension. Seventy-four patients aged >75 yr undergoing surgical repair of hip fracture were randomized into 2 groups of 37 patients each. Group CSA received a continuous spinal anesthetic with a titration of 2.5 mg boluses every 15 min of isobaric bupivacaine, while group SA received a single injection spinal anesthetic with 7.5 mg of isobaric bupivacaine. The overall variations in noninvasive automated arterial blood pressure were not statistically significantly different in the 2 groups at baseline and after CSA or SA (not significant). In the SA group, 68% of patients experienced at least one episode of hypotension (decrease in systolic arterial blood pressure greater than 20% of baseline value) versus 31% of patients in the CSA group (P = 0.005). In the SA group, 51% of patients experienced at least one episode of severe hypotension (decrease in systolic arterial blood pressure more than 30% of baseline value) versus 8% of patients in the CSA group (P < 0.0001). In the CSA group, 4.5 +/- 2 mg of ephedrine was injected versus 11 +/- 2 mg in the SA group (P = 0.005). In the CSA group, 5 mg (2.5-10) of anesthetic solution was required versus 7.5 mg in the SA group (P < 0.0001). We conclude that, in elderly patients undergoing hip fracture repair, CSA provides fewer episodes of hypotension and severe hypotension compared with a single intrathecal injection of 7.5 mg bupivacaine.

Small-dose bupivacaine-sufentanil prevents cardiac output modifications after spinal anesthesia

Spinal injection of small-dose (SD) bupivacaine decreases the likelihood of hypotension compared with large-dose (LD) bupivacaine. We assumed that a SD of bupivacaine could also prevent the decrease in cardiac output (CO). Patients undergoing elective urologic, lower abdominal, or lower limb surgery under spinal anesthesia were included in this prospective randomized study. Spinal injection consisted of 5 mug of sufentanil and either SD (7.5 mg of hyperbaric bupivacaine with glucosemonohydrate 80 mg/mL; n = 19 patients) or LD (12.5 mg of hyperbaric bupivacaine with glucosemonohydrate 80 mg/mL; n = 19 patients). CO (impedance cardiography), arterial blood pressure, and heart rate) were measured at 1 min before performance of spinal block and 2, 10, and 30 min after the intrathecal injection. Sensory level was also assessed at 30 min. CO was higher in the SD group as compared with the LD group from 2 min to 30 min after spinal anesthesia. Moreover, CO increased at 2 min in the SD group and decreased at 10 and 30 min in the LD group compared with baseline value. In conclusion, SD bupivacaine provides successful anesthesia and gives better CO stability than LD.

Prostate anaesthetic block with ropivacaine for urologic surgery

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate prostate anaesthetic block for haemodynamic tolerance and quality of analgesia during and after transurethral surgery.

METHODS

Ninety adult males, ASA III/IV, were randomly assigned to receive a prostate anaesthetic block (n = 45) or spinal anaesthesia (n = 45). The main outcome measurement during anaesthesia, surgery and recovery was haemodynamic tolerance (number of hypotensive episodes, heart rate, systolic and mean blood pressures). Other outcome variables were pain scores during anaesthesia, surgery and every 4 h until 24 h after the end of surgery and amount of oral morphine required during the 24-h postoperative period.

RESULTS

Sixty-six patients were ASA III and 24 ASA IV. Ongoing cardiovascular therapies were comparable between groups. All surgical procedures were performed under good conditions. For patients receiving prostate anaesthetic block, the blood pressure and heart rate did not change significantly during the study period. For patients receiving spinal anaesthesia, the hypotension rate was 55.6% (n = 25) compared to 0 in the prostate anaesthetic block group (P < 0.001); 25 and 4 patients, respectively, required vascular filling and additional ephedrine administration. In both groups, all pain scores were <40 (100 mm visual analogue scale) during the study period. Oral morphine was given during the postoperative period to two prostate anaesthetic block patients and four who had received spinal anaesthesia (not significant).

CONCLUSION

Transurethral surgery under prostate anaesthetic block is safe and assures adequate analgesia during and after surgery.

Rachianesthésie hypobare unilatérale chez le sujet âgé pour la chirurgie traumatique de la hanche : étude pilote

INTRODUCTION

Fractured neck of femur is encountered more frequently as life expectancy increases. All anaesthetic techniques aim to avoid deleterious fall in arterial blood pressure. The haemodynamic effects of hypobaric unilateral spinal anaesthesia have been rarely assessed in patients over 80 year's old. This study aims to do that in a prospective manner.

PATIENTS AND METHODS

Twenty-five patients were enrolled. Following a preload with HES 240/0.576 % (Hesteril) (5 ml/kg) and the administration of an iliofascial block, patients were placed in the lateral decubitus position, operative side uppermost. 3.5 ml of 0.12% hypobaric bupivacaine was administered intrathecally at a rate of 0.25 ml/second. Patients were kept in position for 15 minutes. Systolic, mean and diastolic arterial pressures, heart rate, SaO2 % and ephedrine consumption were recorded at five minutes intervals as was the rate of onset, height and duration of sensory and motor block and extent of bilateralization. Patient and surgeon satisfaction scores were also recorded.

RESULTS

No significant changes in systolic, mean and diastolic pressures, or SaO2 % occurred. Median onset times of sensory and motor block were 8+/-5 and 16+/-7 minutes on the operative side and 30+/-15 and 36+/-15 minutes on the contralateral side in those with bilateralization, respectively. The maximum height of sensory block was T6 for sept patients, T8 for huit patients and T8-T10 for the remainder. Mean duration of sensory and motor block was 134+/-26 and 119+/-24 minutes on the operative side and 100+/-26 and 98+/-25 minutes on the contralateral side, respectively. In 12 patients (48%) bilateralization of their block occurred. Patients and surgeons rated the technique highly.

CONCLUSION

Hypobaric unilateral spinal anaesthesia is a simple technique, produces satisfactory operative conditions and induces very little haemodynamic change in the elderly population.

Issues in the perioperative management of the elderly patient with cardiovascular disease

The elderly patient may show normal physiological changes of the cardiovascular and respiratory systems that accompany aging, as well as features of intrinsic cardiac disease. The latter include: a past history of myocardial infarction or ischaemic heart disease; history of congestive cardiac failure; angina; arterial hypertension (BP >140/90mm Hg); and conduction disorders. A key aspect to the safe and effective anaesthetic management of the elderly patient with cardiac disease is a careful preoperative assessment and optimisation of pre-existing drug therapies. All cardiac medications should be continued up to and including the morning of surgery with the exception of anticoagulation involving warfarin, and perhaps large doses of angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists in patients with hypertension or heart failure. Anaesthetic techniques used in these patients should avoid episodes of excessive hypotension after induction of anaesthesia or large blood loss, or the combination of hypertension and tachycardia after noxious stimulation. The latter physiological disturbances are pivotal for the development of myocardial ischaemia. Both premedication (if used) and anaesthesia should avoid excessive sedation and respiratory depression. The choice of anaesthetic technique may vary between: a balanced technique involving an opiate and a volatile agent; an intravenous technique utilising infusions of propofol; or regional anaesthesia with or without additional sedation. There are no good data to suggest any one technique is better than the rest. The occurrence of ischaemia in the perioperative period may precede the postoperative development of significant cardiac morbidity and mortality (including myocardial infarction or unstable angina, congestive cardiac failure, cerebrovascular accidents, and severe arrhythmias). A number of strategies have been examined to reduce these adverse outcomes. The effect of acute beta-adrenoceptor blockade in treatment-naive patients is associated with reduction in the haemodynamic response to noxious stimuli and decreased ECG evidence of myocardial ischaemia, as well as a reduction in the number of cardiac adverse events. Other drugs (calcium channel antagonists, alpha(2)-agonists and adenosine modulators) have a less predictable influence on both myocardial ischaemia and hard cardiac outcomes. There is inadequate evidence at present to define the optimal time course for acute beta-blockade, or the groups of patients in whom preoperative beta-blockade should be initiated in the absence of contraindications. Nevertheless, addition of beta-blockers to the preoperative regimen should be considered in patients with evidence of or at risk for coronary disease undergoing major surgery. There is also evidence that long-term beta-adrenoceptor or calcium channel blockade or nitrate therapy for the high-risk cardiac patient offers little protection against silent myocardial ischaemia, nonfatal infarction, cardiac failure and cardiac death.

The timing of intravenous crystalloid administration and incidence of cardiovascular side effects during spinal anesthesia: the results from a randomized controlled trial

We conducted a randomized clinical trial to evaluate the efficacy of crystalloids in preventing spinal-induced hypotension (SIH) and cardiovascular side effects (CVSE) in a group of surgical patients. Participants were assigned to receive lactated Ringer's solution at 1-2 mL/min (Placebo group, n = 142); lactated Ringer's at 20 mL/kg starting 20 min before spinal block (n = 130); or lactated Ringer's at 20 mL/kg starting at the time of spinal block (n = 132). SIH was defined as a decrease of > or = 30% in baseline systolic blood pressure, and CVSE as SIH plus nausea, vomiting, or faintness requiring treatment. The incidence of SIH was similar in all treatment groups. Compared to placebo, crystalloid administration at the time of spinal block resulted in a significant reduction in the proportion of patients developing CVSE from 9.9% to 2.3%. The corresponding relative proportion was 0.23 (95% confidence interval, 0.07-0.78; P = 0.019), and one additional case of CVSE was avoided for each 13 patients receiving crystalloids at the time of spinal block instead of placebo. Administration of crystalloids at the time of spinal block seems to be effective because it provides additional intravascular fluids during the period of highest risk of CVSE after spinal anesthesia.

IMPLICATIONS

Crystalloids are frequently administered to nonobstetric patients minutes before spinal anesthesia to prevent cardiovascular side effects (CVSE). This randomized controlled trial shows that although crystalloids administered before spinal block result in no clinical benefit, they significantly reduce the risk of CVSE when administered at the time of spinal block.

Intrathecal anaesthesia for the elderly patient: the influence of the induction position on perioperative haemodynamic stability and patient comfort

Ninety elderly (>65 y) patients were studied to assess the influence of patient position during induction of spinal anaesthesia on the incidence of perioperative hypotension and haemodynamic stability. Prior to induction of anaesthesia, Lactated Ringer's solution (8-10 ml/kg) was administered. In the Sitting Group, intrathecal anaesthesia was performed with the patient in the sitting position. In the Lateral Group, patients assumed the lateral decubitus position. In all cases hyperbaric bupivacaine (10 mg) was administered using a 25 gauge Quincke spinal needle. Patients were placed in the supine (and thereafter lithotomy) position immediately after withdrawing the spinal needle. Incremental doses of ephedrine (5 mg, i.v.) were administered in response to hypotension (>20% of baseline), nausea, vomiting, sweating, skin pallor or impaired consciousness. The mean arterial blood pressure, heart rate and the number of hypotensive episodes requiring ephedrine administration were unaffected by group affiliation. In the Sitting Group, nine patients received 24 doses of ephedrine 5 mg i.v. In the Lateral Group, 21 incremental doses of ephedrine were administered to nine patients. The incidence of nausea, vomiting, sweating and pallor were similar between the groups. Patient comfort was similar. In summary, the incidence of hypotension and hypotension-related adverse effects was similar when intrathecal anaesthesia was induced in the sitting or lateral position. Furthermore, subjective perception of the induction process or anaesthetic experience was not affected by patient position.

Effect of continuous infusion of prostaglandin E1 on hepatic blood flow

STUDY OBJECTIVE

To evaluate the effects of an intravenous infusion of prostaglandin E1 (PGE1) on hepatic blood flow.

DESIGN

Prospective clinical study.

SETTING

University-affiliated hospital.

PATIENTS

16 ASA physical status I and II surgical patients who were scheduled for abdominal surgery.

INTERVENTIONS

Patients were anesthetized with 1% sevoflurane and 66% nitrous oxide. PGE1 0.05 mg/kg/min or PGE1 0.10 mg/kg/min was continuously infused, followed by an infusion of 1000 mL Ringer's acetate solution.

MEASUREMENTS

The hemodynamic effect of PGE1 was examined using pulse dye densitometry (PDD). A nose probe for PDD was used, and 10 mg indocyanine green (ICG) in 2 mL distilled water was bolus-infused into a central venous catheter for each measurement. Cardiac output (CO), circulating blood volume (CBV), and plasma dye clearance rate (K) were monitored from the dye-densitogram. Hepatic blood flow was estimated using the K and CBV values.

MAIN RESULTS

PGE1 did not increase CBV or CO. Even adding a 1000 mL crystalloid infusion did not expand CBV, whereas mean arterial pressure (MAP) significantly decreased from 91.1 +/- 16.5 mmHg to 84.8 +/- 13.5 mmHg (PGE1 0.05 microg/kg/min) and 80.6 +/- 14.4 mmHg (PGE1 0.10 microg/kg/min ) (p < 0.01 compared with control value), then to 72.0 +/- 6.5 mmHg (PGE1 0.10 microg/kg/min + 1000 mL Ringer's acetate) (p < 0.01 compared with control value). Hepatic blood flow changes were 1.46 +/- 0.60 L/min (control), 1.48 +/- 0.45 L/min (PGE1 0.05 microg/kg/min), 1.14 +/- 0.35 L/min (PGE1 0.10 microg/kg/min), and 1.15 +/- 0.19 L/min (PGE1 0.10 microg/kg/min + 1000 mL Ringer's acetate) (no significant difference, p < 0.05). Hepatic blood flow and K values did not statistically significantly differ at each condition.

CONCLUSIONS

PGE1 does not affect blood volume shift, CO, or hepatic blood flow.

The effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia

We evaluated the effects of an infusion of lactated Ringer's (LR) solution on changes in cardiac output (CO) after spinal anesthesia. Seventy-five patients scheduled for lower extremity surgery under spinal anesthesia were studied. We measured CO (impedance cardiography method) and blood pressure for 25 min before and 30 min after spinal anesthesia. Patients were randomly assigned to three groups. In the No Infusion group, no LR solution was given during the period of measurements. The LR Before group received 12 mL/kg of LR solution within 20 min before spinal anesthesia. The LR After group received 12 mL/kg of LR solution within 20 min starting immediately after spinal anesthesia. After spinal anesthesia, CO decreased by 13.9% in the No Infusion group. In the LR Before group, CO increased after the infusion by 20% and returned to baseline value 30 min after spinal anesthesia. In the LR After group, CO increased after spinal anesthesia, and 30 min after spinal anesthesia, CO was 11.3% above baseline. We conclude that the decrease in CO after spinal anesthesia can be prevented by the infusion of an LR solution, with CO reaching the highest value while the infusion is running.

IMPLICATIONS

We studied the effects of lactated Ringer's solution infusion on cardiac output changes after spinal anesthesia. If the patients received no infusion, cardiac output decreased after spinal anesthesia. However, if the patients received lactated Ringer's solution infusion, cardiac output was maintained.

The use of intravenous atropine after a saline infusion in the prevention of spinal anesthesia-induced hypotension in elderly patients

We investigated the efficacy of IV atropine for preventing spinal anesthesia-induced hypotension in elderly patients. Seventy-five patients undergoing transurethral prostate or bladder surgery were randomized to receive either placebo (n = 25), atropine 5 microg/kg (small-dose atropine, n = 25) or atropine 10 microg/kg (large-dose atropine, n = 25) after the induction of spinal anesthesia. All the patients received an IV infusion of 10 mL/kg 0.9% normal saline over 10 min before the induction of anesthesia. The systolic blood pressure decreased in all three groups after spinal anesthesia. There was a significant increase in the mean heart rate in both atropine groups as compared to the placebo group (placebo group: 78 bpm, 95% confidence interval [CI]: 76.6-78.5; small-dose atropine group: 86 bpm, 95% CI 83.9-88.8; large-dose atropine group: 97 bpm, 95% CI 94.5-100.3; P: = 0.001). There was a significant decrease in the incidence of hypotension in patients who received atropine (placebo group: 76%, small-dose atropine group: 52%, large-dose atropine group: 40%, P: = 0.03). The mean dose of ephedrine required was significantly decreased in the atropine groups (placebo group: 12.2 mg [SD= 10.5], small-dose atropine group: 7.4 mg [SD= 10.0], large-dose atropine group: 5.4 mg [SD= 8.7 mg], P: = 0.048). The total amount of IV fluid and number of patients requiring metaraminol in addition to 30 mg of ephedrine were not significantly different among the three groups. Significant side effects, such as confusion, ST segment changes or angina were not detected in any of the patients. We conclude that IV atropine may be a useful supplement to the existing methods in preventing hypotension induced by spinal anesthesia.

IMPLICATIONS

IV atropine increases heart rate in a dose-dependent manner in elderly patients undergoing spinal anesthesia. It reduces the incidence of hypotension and the dose of ephedrine required. Small-dose atropine may be a useful supplement in preventing spinal anesthesia-induced hypotension in elderly patients.

Microparticle-containing oncotic solutions augment in-vitro clot disruption by ultrasound

Echocardiographic contrast agents enhance blood clot disruption by ultrasound. It has been suggested that the microbubbles add nuclei for the enhancement of cavitation by ultrasound. However, microbubbles are rapidly destroyed by the ultrasound energy. We assessed whether non-gas filled colloidal solutions (hyperoncotic medium molecular hydroxyethyl starch and degraded gelatin polypeptides) will facilitate clot disruption by ultrasound. In two separate experiments human blood clots, 200-400 mg in weight, were weighed and then immersed for 15 seconds in 10 ml normal saline solution containing 0%, 0.1%, 1%, 2%, and 5% of hyperoncotic medium molecular hydroxyethyl starch or 0%, 0.035%, 0.175%, 0.35%, and 0.7% degraded gelatin polypeptides. Clots were randomized to 10 seconds 20 kHz ultrasound or immersion without ultrasound. After treatment, the clots were reweighed, and the percent difference in weight was calculated. Non-gas filled microparticle-containing solutions such as hyperoncotic medium molecular hydroxyethyl starch and degraded gelatin polypeptides significantly augmented blood clot disruption by ultrasound. The effect is dependent on the colloidal solution concentration with maximal effect achieved with 1% hyperoncotic medium molecular hydroxyethyl starch and 0.35% degraded gelatin polypeptides.

Choosing general versus regional anesthesia for the elderly

Although clinical perceptions and theoretic considerations suggest regional anesthesia should be safer than general anesthesia in elderly patients, current studies indicate no difference in outcomes. Regional anesthesia may still prove superior to general anesthesia if the right patient population or right endpoints are identified for comparison. A study of consequence of outcome, comparing the two approaches has created an expansion of the definition of anesthesia-related complications.

A study to determine the optimum dose of metaraminol required to increase blood pressure by 25% during subarachnoid anaesthesia

We studied dosage optimization for metaraminol when managing hypotension during subarachnoid anaesthesia. Twenty patients aged 53 to 84 years, were recruited. Non-invasive blood pressure (BP) and heart rate were recorded one-minutely. A series of four i.v. metaraminol boluses (0.25 to 1.0 mg per 50 kg adult) were administered. From individual patient time plots of BP predicted dosages for a 25% elevation in BP were estimated. Dose-related elevations in systolic BP [mean (SD)] occurred following dosages of 0.5 mg [25 (11)%] and 1.0 mg [50 (23)%]. Similar elevations occurred in mean and diastolic BP. Overall estimated dosage (median) to produce a 25% elevation in systolic BP was 0.5 mg (per 50 kg adult). However, individual patient responses varied (10-90th centiles = 0.23 to 0.80 mg). Thus, we now recommend a starting dose of 0.25 mg, increasing to 0.5 mg if necessary, to treat hypotension (25% decrease in systolic BP) during subarachnoid anaesthesia.

Incidence and time course of cardiovascular side effects during spinal anesthesia after prophylactic administration of intravenous fluids or vasoconstrictors

We studied the time course of arterial hypotension and/or bradycardia requiring treatment during spinal anesthesia and compared the efficacy of i.v. fluid or vasoconstrictor administration for the prevention of these side effects. Patients (n = 1066) were randomly allocated to either a volume group (lactated Ringer's solution 15 mL/kg within 15 min before spinal anesthesia), a dihydroergotamine group (10 microg/kg i.m. 15 min before anesthesia), or a placebo group. All patients breathed O2-enriched air during spinal anesthesia (4 mL of plain 0.5% bupivacaine). With the placebo, there were side effects (mean incidence 22.9%) for up to 45 min after the start of anesthesia. Dihydroergotamine reduced the incidence of side effects, preferentially the late ones, more (mean incidence 11.8%) than fluid administration (mean incidence 16.9%), which was effective only during the first 15 min of anesthesia. Both heart rate and arterial pressure decreased within 15 min before the manifestation of symptoms. In a subgroup of patients, the incidence of side effects (8%) was greatly reduced by the intraoperative application of both sedatives and opioids. We conclude that cardiovascular side effects may occur at any time during spinal anesthesia. Fluid administration reduced the incidence of early events, but dihydroergotamine the late events.

IMPLICATIONS

Cardiovascular side effects requiring treatment occurred at any time during spinal anesthesia in our placebo-controlled study, regardless of the prophylactic regimen (fluid infusions versus dihydroergotamine).