Cardiovascular effects of low-dose spinal anaesthesia as a function of age: An observational study using echocardiography

Left ventricular end-diastolic pressure response to spinal anaesthesia in euvolaemic vascular surgery patients

PURPOSE

Regional anaesthesia techniques provide highly effective alternative to general anaesthesia. Existing evidence on the effect of spinal anaesthesia (SA) on cardiac diastolic function is scarce. This study aimed to evaluate the effects of a single-injection, low-dose SA on left ventricular end-diastolic pressures (LVEDP) using echocardiography in euvolaemic patients undergoing elective vascular surgery.

METHODS

This is a prospective study in adult patients undergoing elective vascular surgery with SA. Patients with contraindications for SA or significant valvular disease were excluded. During patients' evaluations fluid administration was targeted using arterial waveform monitoring. All patients underwent echocardiographic studies before and after SA for the assessment of indices reflective of diastolic function. LVEDP was evaluated using the E/e' ratio. Blood samples were drawn to measure troponin and brain natriuretic peptide (BNP) levels before and after SA.

RESULTS

A total of 62 patients (88.7% males, 71.00 ± 9.42 years) were included in the analysis. In total population, end-diastolic volume (EDV, 147.51 ± 41.36 vs 141.72 ± 40.13 ml; p = 0.044), end-systolic volume (ESV, 69.50 [51.50] vs 65.00 [29.50] ml; p < 0.001) and E/e' ratio significantly decreased (10.80 [4.21] vs. 9.55 [3.91]; p = 0.019). In patients with elevated compared to those with normal LVEDP, an overall improvement in diastolic function was noted. The A increased (- 6.58 ± 11.12 vs. 6.46 ± 16.10; p < 0.001) and E/A decreased (0.02 ± 0.21 vs. - 0.36 ± 0.90; p = 0.004) only in the elevated LVEDP group. Patients with elevated LVEDP had a greater decrease in E/e' compared to those with normal LVEDP (- 0.03 ± 2.39 vs. - 2.27 ± 2.92; p = 0.002).

CONCLUSION

This study in euvolaemic patients undergoing elective vascular surgery provides evidence that SA improved LVEDP.

The impact of spinal anesthesia on cardiac function in euvolemic vascular surgery patients: insights from echocardiography and biomarkers

Existing evidence of the effect of spinal anesthesia (SA) on cardiac systolic function is scarce and inconclusive. This study aimed to evaluate the effects induced by a single injection of SA for elective vascular surgery on left (LV) and right (RV) ventricular systolic performance using transthoracic echocardiography (TTE). A prospective study. Single-center study, university hospital. Adult patients undergoing elective vascular surgery with SA. During patients' evaluations fluid administration was targeted using arterial waveform monitoring. All patients underwent TTE studies before and after SA induction for the assessment of indices reflective of LV and RV systolic function. Blood samples were drawn to measure troponin and brain natriuretic peptide (BNP) levels. A total of 62 patients (88.7% males, 71.00 ± 9.42 years) were included in the study. The primary outcome was the difference before and after SA in LV ejection fraction (LVEF) and tricuspid annular plane systolic excursion (TAPSE). In total population, LVEF significantly increased after SA 53.07% [16.51]vs 53.86% [13.28]; p < 0.001). End-systolic volume (ESV, 69.50 [51.50] vs. 65.00 [29.50] ml; p < 0.001) decreased while stroke volume (SV) insignificantly increased (70.51 ± 16.70 vs. 73.00 ± 18.76 ml; p = 0.131) during SA. TAPSE remained unchanged (2.23 [0.56] vs. 2.25 [0.69] mm; p = 0.558). In patients with impaired compared to those with preserved LV systolic function, the changes evidenced in LVEF (7.49 ± 4.15 vs. 0.59 ± 2.79; p < 0.001), ESV (-18.13 ± 18.20 vs-1.53 ± 9.09; p < 0.001) and SV (8.71 ± 11.96 vs-1.43 ± 11.89; p = 0.002) were greater. This study provides evidence that SA in patients undergoing elective vascular surgery improved LV systolic function, while changes in RV systolic function are minimal.

Evaluation of the Predictive Character of the Expiratory Inferior Vena Cava/Abdominal Aorta (eIVC/Ao) Index for Minimum Blood Pressure Following Spinal Anesthesia With 0.5% Hyperbaric Bupivacaine

Spinal anesthesia has many side effects, one of them being a drop in blood pressure (BP). Identifying predictive factors for this drop is a clear matter of concern. In this regard, the expiratory inferior vena cava/abdominal aorta (eIVC/Ao) index has already been spotted as such for doses of 0.5% hyperbaric bupivacaine greater than 12mg. Departing from the demonstrated correlation between this index and hypotension post-spinal anesthesia, our study aimed to (1) evaluate whether an eIVC/Ao index greater than 0.7, thus defining non-hypovolemic patients, can also predict minimal BP for doses inferior to 12mg and (2) identify other predictive factors for minimal BP post-spinal anesthesia. Lastly, we verified whether preoperative fasting induces hypovolemia.  This single-center prospective observational pilot study included 20 patients. The baseline measurements of BP, eIVC/Ao index, and fasting time were recorded at time T0'. Then spinal anesthesia was administered with 0.5% hyperbaric bupivacaine in doses inferior to 12 mg. The patients' systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and metameric levels were each recorded at times T5', T10', T15', and T20'.  The results indicated that baseline DBP was predictive of low DBP and minimum MAP, which reflect myocardial perfusion and systemic pressures, respectively. Therefore, it should trigger prophylaxis (spinal-lateralized, continuous, or lower dose) in patients with a low DBP baseline. Additionally, baseline SBP was predictive of minimum SBP, an independent risk factor for post-anesthetic hypotension if its baseline is less than 120 mmHg. Although female gender was linked to minimum SBP, other confounding factors (size, dose administered, and type of surgery related to gender) must also be considered. Moreover, a correlation was established between height and MAP in parturients. Hypotension was not recorded at local anesthetic (LA) doses between 8 and 12 mg and the doses administered were sufficient to achieve the metameric levels required for surgery (ether tests). Since 8 mg of 0.5% hyperbaric bupivacaine achieved the same level as 12 mg, lower doses of LA might prevent a significant drop in BP and its deleterious effects. Therefore, in the current cohort, the eIVC/Ao index was not predictive of minimum BP during spinal anesthesia with doses less than 12 mg of 0.5% hyperbaric bupivacaine. However, predictive factors for minimum BP included gender and baseline SBP (for minimum SBP), height and baseline DBP (for minimum MAP), and baseline DBP (for minimum DBP). Lastly, preoperative fasting did not cause hypovolemia.

Preoperative echocardiography as a predictor of spinal anesthesia-induced hypotension in older patients with mild left ventricular diastolic dysfunction: a retrospective observational study

BACKGROUND

Spinal anesthesia-induced hypotension (SAH) frequently occurs in older patients, many of whom have mild left ventricular (LV) diastolic dysfunction, often asymptomatic at rest. This study investigated the association between preoperative echocardiographic measurements and SAH in older patients with mild LV diastolic dysfunction.

METHODS

We conducted a retrospective observational study using data from electronic medical records. The patients ≥ 65 years old who underwent spinal anesthesia for urologic surgery between January 2016 and December 2017 and whose preoperative echocardiography within 6 months before surgery revealed grade I LV diastolic dysfunction were recruited. SAH was investigated using the anesthesia records. Logistic regression and receiver operating characteristic (ROC) curve analyses were performed.

RESULTS

A total of 163 patients were analyzed. SAH and significant SAH developed in 55 (33.7%) patients. The mitral inflow E velocity was an independent risk factor for SAH (odds ratio [OR], 0.886; 95% confidence interval [CI], 0.845-0.929; P < 0.001). The area under the ROC curve for mitral inflow E velocity to predict SAH was 0.819 (95% CI, 0.752-0.875; P < 0.001). If mitral inflow E velocity was ≤ 60 cm/s, SAH was predicted with a sensitivity of 83.6% and specificity of 70.4%.

CONCLUSIONS

The preoperative mitral inflow E velocity demonstrated the greatest predictability of SAH in older patients with mild LV diastolic dysfunction. This may assist in identifying patients at high risk of SAH and guiding preventive strategies in the future.

Neuraxial Anesthesia in Patients With Aortic Stenosis: A Systematic Review

Neuraxial anesthesia (NA) has been contraindicated in patients with aortic stenosis (AS) due to concerns of sympathetic blockade and hemodynamic instability. These considerations are based on precautionary expert recommendations, supported by expected physiologic effects, but in the absence of any published scientific evidence. In light of the increasing elderly population and the prevalence of AS, this systematic review compiles available literature on NA in patients with AS to address the understanding of the anesthetic practice and safety in this population. Using a systematic approach, PubMed, Embase, and Web of Science were searched for studies of patients with AS who exclusively received NA. Primary outcomes included intraoperative and postoperative complications. Of 1,433 citations, 61 met full-text inclusion criteria, including 3,228 patients undergoing noncardiac (n = 3,146, 97.5%), obstetric (n = 69, 2.1%), and cardiac (n = 13, 0.4%) procedures. Significant data heterogeneity (local anesthetic dosing, intraoperative interventions, and measured outcomes) prevented formal metanalysis, but descriptive data are presented. Spinal block (n = 2,856, 88.5%) and epidural anesthesia (n = 397, 12.3%) were administered most frequently. Hypotension requiring vasopressors was the most common intraoperative complication-noncardiac (n = 16, 9.9%), obstetric (n = 6, 13.0%), and cardiac (n = 1, 7.7%)-with resolution in all patients and no reported intraoperative cardiovascular collapse or mortality. The relative risk of different AS severities remains unclear, and optimal medication dosing remains elusive. The authors' data suggested that NA may not be contraindicated in carefully selected patients with AS. The authors' results should inform the design of future prospective studies comparing NA and general anesthesia in patients with AS.

Intrathecal ropivacaine versus bupivacaine in a non-obstetric population- A meta-analysis and trial sequential analysis

Background and Aims

Intrathecal bupivacaine is used for anaesthesia and analgesia but is associated with hypotension. Ropivacaine is an alternative drug that may have fewer cardiotoxic and neurotoxic events. This meta-analysis investigated whether intrathecal ropivacaine is associated with reduced hypotension as compared to bupivacaine.

Methods

The meta-analysis is registered in the International Prospective Register of Systematic Reviews (PROSPERO). The databases PubMed, Cinahl Plus, Google Scholar, and Scopus were searched, and papers from January 1980 to January 2023 were deemed eligible and filtered using predetermined inclusion and exclusion criteria. The primary outcome was the incidence of hypotension. Secondary outcomes were the duration of sensory block, duration of motor block, incidence of bradycardia, ephedrine usage, and duration of analgesia. Jadad scores were used to evaluate the quality of the papers. RevMan statistical software® utilised inverse variance and a random effect model to calculate the standardised mean difference with 95% confidence intervals for continuous variables and the Mantel-Haenszel test and the random effect model to calculate the odds ratio for dichotomous variables.

Results

Thirty-three papers, including 2475 patients in total, were included. The Jadad score was between 1 and 5. The incidence of hypotension was significantly higher with intrathecal bupivacaine than with ropivacaine (P = 0.02). The duration of sensory block (P < 0.001) and motor block (P < 0.001) was prolonged with intrathecal bupivacaine. The duration of analgesia favoured intrathecal bupivacaine (P = 0.003).

Conclusion

Intrathecal ropivacaine has a reduced incidence of hypotension and a reduced duration of sensory block compared to bupivacaine.

Fractional spinal anaesthesia in high-risk elderly patients for orthopaedic surgery - Case series

Elderly patients coming for orthopaedic surgeries usually have many comorbidities. This makes them potentially vulnerable to haemodynamic instability with a conventional bolus dose of spinal anaesthetic. Fractionating the spinal dose was reported to have haemodynamic stability with a longer duration. Here, we present five cases of high-risk elderly patients with multiple comorbidities who presented for orthopaedic surgeries and were successfully managed with fractional spinal anaesthesia.

External Validation of the Revised Cardiac Risk Index and the Geriatric-Sensitive Perioperative Cardiac Risk Index in Oldest Old Patients Following Surgery Under Spinal Anaesthesia; a Retrospective Cross-Sectional Cohort Study

Background

The Revised Cardiac Risk Index (RCRI) and the Geriatric Sensitive Cardiac Risk Index (GSCRI) estimate the risk of postoperative major adverse cardiac events (MACE) regardless of the type of anesthesia and without specifying the oldest old patients. Since spinal anesthesia (SA) is a preferred technique in geriatrics, we aimed to test the external validity of these indices in patients ≥ 80 years old who underwent surgery under SA and tried to identify other potential risk factors for postoperative MACE.

Methods

The performance of both indices to estimate postoperative in-hospital MACE risk was tested through discrimination, calibration, and clinical utility. We also investigated the correlation between both indices and postoperative ICU admission and length of hospital stay (LOS).

Results

The MACE incidence was 7.5%. Both indices had limited discriminative (AUC for RCRI and GSCRI were 0.69 and 0.68, respectively) and predictive abilities. The regression analysis showed that patients with atrial fibrillation (AF) were 3.77 and those with trauma surgery were 2.03 times more likely to exhibit MACE, and the odds of MACE increased by 9% for each additional year above 80. Introducing these factors into both indices (multivariable models) increased the discriminative ability (AUC reached 0.798 and 0.777 for RCRI and GSCRI, respectively). Bootstrap analysis showed that the predictive ability of the multivariate GSCRI but not the multivariate RCRI improved. Decision curve analysis (DCA) showed that multivariate GSCRI had superior clinical utility when compared with multivariate RCRI. Both indices correlated poorly with postoperative ICU admission and LOS.

Conclusion

Both indices had limited predictive and discriminative ability to estimate postoperative in-hospital MACE risk and correlated poorly with postoperative ICU admission and LOS, following surgery under SA in the oldest-old patients. Updated versions by introducing age, AF, and trauma surgery improved the GSCRI performance but not the RCRI.

Relationship of Abdominal Circumference and Trunk Length With Spinal Anesthesia Block Height in Geriatric Patients Undergoing Transurethral Resection of Prostate

INTRODUCTION

Spinal anesthesia is commonly used for various surgical procedures. Prediction of spinal anesthesia block height is always a challenging task for anesthetists. Higher than desired levels of spinal anesthesia blocks are associated with serious side effects, while inadequate block height does not provide satisfactory surgical anesthesia. In this study, we observed the relationship between the ratio of trunk length (TL) and square of the abdominal circumference (AC²) and spinal anesthesia sensory block height in geriatric patients undergoing transurethral resection of the prostate (TURP).

MATERIAL & METHODS

This is a cross-sectional study conducted at the Aga Khan University Hospital Karachi, Pakistan, on geriatric patients undergoing TURP under spinal anesthesia. Forty-three elderly patients (American Society of Anaesthesiology level I-III) between 60 and 80 years were recruited for the study. In hospital wards, trunk length (TL) and abdominal circumference were recorded before the procedure. In the operating rooms, spinal anesthesia was performed at L3-L4 intervertebral space with 0.5% hyperbaric bupivacaine 10mg (2mls). Block height was measured by the placement of ice pads at different dermatomes. Spearman rank correlation coefficient was used to analyze the physical parameters (TL/AC²) and spinal anesthesia block height.  Results: The ratio of trunk length and square of the abdominal circumference (TL/AC²) correlates with spinal anesthesia block height in geriatric patients, where the spearman rank correlation coefficient was r =-0.284 with p = 0.015.

CONCLUSION

The ratio of the long axis (TL) and transection area of the abdomen (AC²), which coincides with (TL/AC²), correlated with spinal anesthesia sensory block height. Hence, elderly patients with a low TL/AC² ratio will have higher block height after spinal anesthesia.

The efficacy and safety of pre-emptive methoxamine infusion in preventing hypotension by in elderly patients receiving spinal anesthesia: A PRISMA-compliant protocol for systematic review and meta-analysis

BACKGROUND

Hypotension is frequent after spinal anesthesia, especially in elderly patients. Whether pre-emptive methoxamine infusion is effective and safe to prevent spinal anesthesia-induced hypotension is still a controversial issue, to dress this knowledge lack, we performed a systemic review and meta-analysis to evaluated it.

PARTICIPANTS

Elderly patients undergoing spinal anesthesia.

INTERVENTIONS

Administration of methoxamine prior to spinal anesthesia.

METHODS

We searched PUBMED, Cochrane Library, EMBASE, China National Knowledge Infrastructure, Wanfang Database, and VIP Database, Chinese BioMedical Literature & Retrieval System from January 1st 1978 to February 28th 2022. Primary outcomes of interests included hemodynamic parameters, such as systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate. Secondary outcomes of interests included the incidence of intraoperative hypotension, bradycardia, nausea and vomiting, vasopressors requirement, intraoperative blood loss. For continuous or dichotomous variables, treatment effects were calculated as weighted mean difference or odds ratio, respectively.

RESULTS

Our search yielded 8 randomized controlled trials including 480 patients, and 240 patients were allocated into methoxamine group and 240 into control group. Meta-analysis demonstrated that pre-emptive methoxamine infusion in preventing hypotension by in elderly patients receiving spinal anesthesia had higher blood pressures, lower heart rates. Compared with the control group, the incidence of perioperative hypotension in elderly patients was lower, and elderly patients had less requirement for vasopressor in methoxamine group.

CONCLUSION

This meta-analysis demonstrated that pre-emptive methoxamine infusion in elderly patients receiving spinal anesthesia can improve blood pressure, slow down heart rate, reduce the incidence of hypotension and requirement for vasopressor. However, these findings should be interpreted rigorously. Further well-conducted trials are required to confirm this.

Comparative study between suprasternal and apical windows: a user-friendly cardiac output measurement for the anesthesiologist

INTRODUCTION

Transthoracic echocardiography is a safe and readily available tool for noninvasive monitoring of Cardiac Output (CO). The use of the suprasternal window situated at the sternal notch can be an alternative approach for estimating blood flow. The present study aimed to compare two methods of CO calculation. We compared the descending aorta Velocity-Time Integral (VTI) measurement from the suprasternal window view with the standard technique to determine CO that uses VTI measurements from the LVOT (Left Ventricular Outflow Tract) view. We also aimed to find out whether after basic training a non-echocardiographer operator can obtain reproducible measurements of VTI using this approach.

METHODS

In the first part of the study, 26 patients without known cardiovascular diseases were evaluated and VTI data were acquired from the suprasternal window by a non-echocardiographer and an echocardiographer. Next, 17 patients were evaluated by an echocardiographer only and VTI and CO measurements were obtained from suprasternal and apical windows. Data were analyzed using the Bland and Altman method (BA), correlation and regression.

RESULTS

We found a strong correlation between measurements obtained by a non-expert and an expert echocardiographer and detected that an inexperienced trainee can acquire VTI measurements from the suprasternal window view. Regarding agreement between CO measurements, data obtained showed a positive correlation and the Bland and Altman analysis presented a total variation of 38.9%.

CONCLUSION

Regarding accuracy, it is likely that TTE (Transthoracic Echocardiogram) measurements of CO from the suprasternal window view are comparable to other minimally invasive techniques currently available. Due to its user-friendliness and low cost, it can be a convenient technique for obtaining perioperative hemodynamic measurements, even by inexperienced operators.

Effect of ondansetron on spinal anesthesia-induced hypotension in non-obstetric surgeries: a randomised, double-blind and placebo-controlled trial

BACKGROUND AND OBJECTIVES

Spinal anesthesia is an effective technique for many surgical procedures, but it is often associated with an increased risk of potentially deleterious hemodynamic disturbances. The benefits of prophylactic ondansetron for preventing spinal anesthesia-induced hypotension are still uncertain. Therefore, this study aimed to compare the effect of ondansetron and placebo before spinal block on the incidence of hypotension in patients having non-obstetric surgeries.

METHODS

Randomized, double-blind, parallel-group, superiority trial with a 1:1 allocation ratio. A total of 144 patients scheduled for non-obstetric surgeries with an indication for spinal anesthesia were randomized. Patients received intravenous ondansetron (8mg) or placebo before standard spinal anesthesia. The primary outcome was the rate of hypotension in the first 30 minutes after spinal anesthesia.

RESULTS

Hypotension occurred in 20 of 72 patients (27.8%) in the ondansetron group and in 36 of 72 patients (50%) in the placebo group (Odds Ratio-OR=0.38; 95% Confidence Interval-CI 0.19 to 0.77; p=0.007). Fewer patients in the ondansetron group required ephedrine compared to the placebo group (13.9% vs. 27.8%; OR=0.42; 95% CI 0.18 to 0.98; p=0.04). Exploratory analyses revealed that ondansetron may be more effective than placebo in patients aged 60 years or older (OR=0.12; 95% CI 0.03 to 0.48; p=0.03). No difference in heart rate variations was observed.

CONCLUSION

Our findings suggest that ondansetron can be a viable and effective strategy to reduce both the incidence of spinal anesthesia-induced hypotension and vasopressors usage in non-obstetric surgeries.

Hemodynamic effects of norepinephrine versus phenylephrine infusion for prophylaxis against spinal anesthesia-induced hypotension in the elderly population undergoing hip fracture surgery: a randomized controlled trial

Background

Elderly population are at increased risk of spinal anesthesia-induced hypotension increasing their risk for postoperative morbidity and mortality. This study aimed to compare the hemodynamic effects of prophylactic infusion of norepinephrine (NE) versus phenylephrine (PE) in elderly patients undergoing hip fracture surgery under spinal anesthesia.

Methods

Elderly patients scheduled for hip fracture surgery were randomized to receive either NE infusion (8 µg/min) (NE group, n = 31) or PE infusion (100 µg/min) (PE group, n = 31) after spinal anesthesia. Outcomes included mean heart rate, mean blood pressure, cardiac output, incidence of spinal anesthesia-induced hypotension, incidence of bradycardia, and incidence of hypertension.

Results

Sixty-two patients with a mean age of 71 ± 6 years were included in the final analysis (31 patients in each group). The NE group showed a higher mean heart rate and cardiac output than the PE group. The NE group had a lower incidence of reactive bradycardia (10% vs. 36%, P = 0.031) and hypertension (3% vs. 36%, P = 0.003) than the PE group. No study participant developed hypotension, and the mean blood pressure was comparable between the two groups.

Conclusions

Both NE and PE infusions effectively prevented spinal anesthesia-induced hypotension in elderly patients undergoing hip fracture surgery. However, NE provided more hemodynamic stability than PE; maintaining the heart rate, higher cardiac output, less reactive bradycardia, and hypertension.

Effects of spinal anesthesia and sedation with dexmedetomidine or propofol on cerebral regional oxygen saturation and systemic oxygenation a period after spinal injection

PURPOSE

To evaluate changes in cerebral regional oxygen saturation (rSO₂) after spinal anesthesia and compare the changes in rSO₂ and systemic oxygenation between dexmedetomidine sedation and propofol sedation.

METHODS

Thirty-six patients scheduled to undergo transurethral surgery under spinal anesthesia were randomly assigned to the dexmedetomidine (n = 18) and propofol groups (n = 18). We used near-infrared spectroscopy sensors to measure rSO₂, and obtained data from each side were averaged. After oxygen insufflation, baseline measurements of mean arterial blood pressure (MAP), heart rate, rSO₂, pulse oximetry saturation (SpO₂), bispectral index, and body temperature were made. After spinal anesthesia, we measured these parameters every 5 min. Twenty minutes after spinal injection, dexmedetomidine or propofol administration was started. We measured each parameter at 10, 25, and 40 min after the administration of dexmedetomidine or propofol.

RESULTS

The baseline rSO₂ in the dexmedetomidine group was 71.3 ± 7.3%, and that in the propofol group was 71.8 ± 5.6%. After spinal anesthesia, rSO₂ in both groups decreased significantly (dexmedetomidine group: 65.4 ± 6.9%; propofol group: 64.3 ± 7.4%). After administering sedatives, rSO₂ was equivalent after spinal anesthesia. rSO₂ was comparable between the two groups. MAP and SpO₂ were significantly higher in the dexmedetomidine group than in the propofol group.

CONCLUSION

Spinal anesthesia decreased rSO₂; however, the decline was not severe. Dexmedetomidine and propofol did not compromise cerebral oxygenation under spinal anesthesia. Nevertheless, MAP and SpO₂ were more stable in dexmedetomidine sedation than in propofol sedation. Dexmedetomidine may be suitable for spinal anesthesia.

Control of Spinal Anesthesia-Induced Hypotension in Adults

Spinal anesthesia-induced hypotension (SAIH) occurs frequently, particularly in the elderly and in patients undergoing caesarean section. SAIH is caused by arterial and venous vasodilatation resulting from the sympathetic block along with a paradoxical activation of cardioinhibitory receptors. Bradycardia after spinal anesthesia (SA) must always be treated as a warning sign of an important hemodynamic compromise. Fluid preloading (before initiation of the SA) with colloids such as hydroxyethyl starch (HES) effectively reduces the incidence and severity of arterial hypotension, whereas crystalloid preloading is not indicated. Co-loading with crystalloid or colloid is as equally effective to HES preloading, provided that the speed of administration is adequate (ie, bolus over 5 to 10 minutes). Ephedrine has traditionally been considered the vasoconstrictor of choice, especially for use during SAIH associated with bradycardia. Phenylephrine, a α₁ adrenergic receptor agonist, is increasingly used to treat SAIH and its prophylactic administration (ie, immediately after intrathecal injection of local anesthetics) has been shown to decrease the incidence of arterial hypotension. The role of norepinephrine as a possible alternative to phenylephrine seems promising. Other drugs, such as serotonin receptor antagonists (ondansetron), have been shown to limit the blood pressure drop after SA by inhibiting the Bezold–Jarisch reflex (BJR), but further studies are needed before their widespread use can be recommended.

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

Background

Hypotension 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.

Methods

This 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.

Results

Thirty-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).

Conclusion

CO 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.

Effects of Spinal Anaesthesia on Left Ventricular Function: An Observational Study using Two-Dimensional Strain Echocardiography

Objective

Hypotension frequently occurs during spinal anaesthesia (SA), especially in the elderly. This side effect could have a cardiac component per se (myocardial contractility impairment). Two-dimensional (2D) strain and strain rate imaging are new echocardiographic methods allowing an accurate assessment of myocardial function by quantifying myocardial deformation. Allowing quantification of minor myocardial dysfunction not detectable by standard echocardiography, strain imaging could bring new perspective on the cardiac effect of SA. Our objective was to evaluate the effects of SA on left ventricular function assessed by 2D strain echocardiography.

Methods

In this prospective observational study, we enrolled 20 patients older than 60 years, who underwent elective lower-limb surgery under SA. Myocardial strain imaging were collected before and 20 minutes after SA (injection of 10 mg of isobaric bupivacaine with 5 μg of sufentanil).

Results

We observed an increase in global longitudinal reconnoitering (Δ-0.2±0.3% s^-1; p<0.005), whereas left ventricular ejection fraction was not modified by SA.

Conclusion

This slight increase in myocardial contractility could be an adaptive mechanism to compensate the preload decrease and limit the blood pressure drop.

Maternal cardiovascular hemodynamics in normotensive versus preeclamptic pregnancies: a prospective longitudinal study using a noninvasive cardiac system (NICaS™)

BACKGROUND

Preeclampsia is among the most common medical complications of pregnancy. The clinical utility of invasive hemodynamic monitoring in preeclampsia (e.g., Swan-Ganz catheter) is controversial. Thoracic impedance cardiography (TIC) and Doppler echocardiography are noninvasive techniques but they both have important limitations. NICaS™ (NI Medical, PetachTikva, Israel) is a noninvasive cardiac system for determining cardiac output (CO) that utilizes regional impedance cardiography (RIC) by noninvasively measuring the impedance signal in the periphery. It outperformed any other impedance cardiographic technology and was twice as accurate as TIC.

METHODS

We used the NICaS™ system to compare the hemodynamic parameters of women with severe preeclampsia (PET group, n = 17) to a cohort of healthy normotensive pregnant women with a singleton pregnancy at term (control group, n = 62) (1/2015-6/2015). Heart rate (HR), stroke volume (SV), CO, total peripheral resistance (TPR) and mean arterial pressure (MAP) were measured 15-30 min before CS initiation, immediately after administering spinal anesthesia, immediately after delivery of the fetus and placenta, at the abdominal fascia closure and within 24-36 and 48-72 h postpartum.

RESULTS

The COs before and during the CS were significantly higher in the control group compared to the PET group (P < .05), but reached equivalent values within 24-36 h postpartum. CO peaked at delivery of the newborn and the placenta and started to decline afterwards in both groups. The MAP and TPR values were significantly higher in the PET group at all points of assessment except at 48-72 h postpartum when it was still significantly higher for MAP while the TPR only exhibited a higher trend but not statistically significant. The NICaS™ device noninvasively demonstrated low CO and high TPR profiles in the PET group compared to controls.

CONCLUSIONS

The immediate postpartum period is accompanied by the most dramatic hemodynamic changes and fluid shifts, during which the parturient should be closely monitored. The NICaS™ device may help the clinician to customize the most optimal management for individual parturients. Our findings require validation by further studies on larger samples.

Maternal hemodynamics in late gestation and immediate postpartum in singletons vs. twin pregnancies

PURPOSE

Differences in hemodynamic changes during a cesarean section (CS) between twin and singleton pregnancies are poorly defined. The Non-Invasive Cardiac System (NICaS) is an impedance device that measures cardiac output (CO) and its derivatives. We compared maternal cardiac parameters using NICaS™ in singleton and twins before and during delivery, as well at the early puerperium in healthy women undergoing CS at term.

METHODS

This prospective longitudinal study included women with twin (n = 27) or singleton pregnancies (n = 62) whose hemodynamic parameters were assessed by NICaS before an elective CS, after spinal anesthesia, immediately after delivery, after fascia closure, and within 24-36 and 48-72 h postpartum.

RESULTS

By 24-36 h postpartum, the mean arterial pressure and the total peripheral resistance equaled preoperative values in both groups. The CO increased throughout the CS and peaked immediately after delivery in the singleton group (P < 0.0001), after which it abruptly began to decline until reaching a nadir 24-36 h after delivery (P < 0.0001), while it remained steady throughout the CS and then dropped until 24-36 h after delivery in the twin group (P < 0.05). None of the studied parameters differed significantly between the groups for the 24-36 and 48-72 h postpartum measurements.

CONCLUSIONS

Hemodynamic parameters immediately before, during and shortly after CS in singleton and twin pregnancies are equivalent. Further evaluations of the value of NICaS™ in assessing cardiovascular-related pregnancy complications are warranted.

Cardiac hemodynamics before, during and after elective cesarean section under spinal anesthesia in low-risk women

OBJECTIVE

The aim of this study was to describe maternal central hemodynamic parameters before and during delivery as well at the early puerperium in healthy women undergoing elective cesarean section (CS) at term.

STUDY DESIGN

The noninvasive Cardiac System (NICaS, NI Medical, Petah-Tikva, Israel) is a regional impedance device that measures cardiac output (CO) and its derivatives with a good correlation with the gold standard Swan-Ganz catheter. We performed a prospective longitudinal study of healthy women with a singleton pregnancy at term. Maternal hemodynamic parameters were assessed by the NICaS at six time points: a few minutes before undergoing an elective CS, immediately after receiving spinal anesthesia, immediately after delivery of the fetus and placenta, after abdominal fascia closure, and within 24 to 36 and 48 to 72 h postpartum.

RESULT

Sixty-one consenting women were recruited during the study period (January 2015 to June 2015). Baseline (pre-CS) mean arterial pressure (MAP) was 87.7±7.9 mm Hg, baseline CO was 7.5±1.7 l per min and baseline total peripheral resistance (TPR) was 994±301 dyne × s per cm⁵. After spinal anesthesia CO significantly increased by 13%, no significant changes were observed in MAP or TPR. Immediately after delivery, a nadir for all parameters was reached: MAP and TPR were significantly reduced by 8% and 26%, respectively (comparing to pre-CS), and CO further increased by 9% (24% comparing to pre-CS). After fascia closure, partial recoveries of all parameters were observed. Twenty-four to thirty-six hours postpartum MAP returned to pre-CS values, while CO and TPR reached -9% and +11% comparing to baseline, respectively. None of the parameters differed significantly between 24 to 36 and 48 to 72 h postpartum.

CONCLUSION

Significant hemodynamic changes (reduction of TPR and increase of CO) take place at the time of delivery of fetus and placenta. Knowledge of normal hemodynamic values using a reliable noninvasive technique during various stages of pregnancy and the postpartum period is feasible, and might assist clinicians in assessing the level of patient deviation from expected cardiac performance, especially in high-risk women.

Prophylactic phenylephrine infusion for the prevention of hypotension after spinal anesthesia in the elderly: a randomized controlled clinical trial

STUDY OBJECTIVE

Hypotension frequently occurs during spinal anesthesia (SA), especially in the elderly. Phenylephrine is effective to prevent SA-induced hypotension during cesarean delivery. The objective of this study was to evaluate the efficacy and safety of prophylactic infusion of phenylephrine after SA for orthopedic surgery in the elderly.

DESIGN

This prospective, randomized, double-blind, and placebo-controlled study included 54 patients older than 60 years undergoing elective lower limb surgery under SA (injection of 10 mg of isobaric bupivacaine with 5 μg of sufentanyl).

INTERVENTION

Patients were randomized to group P (100-μg/mL solution of phenylephrine solution at 1 mL/min after placement of SA) or the control group C (0.9% isotonic sodium chloride solution). The flow of the infusion was stopped if the mean arterial blood pressure (MAP) was higher than the baseline MAP and maintained or restarted at 1 mL/min if MAP was equal to or lower than the baseline MAP. Heart rate and MAP were collected throughout the case.

MEASUREMENTS

Hypotension was defined by a 20% decrease and hypertension as a 20% increase from baseline MAP. Bradycardia was defined as a heart rate lower than 50 beats per minute.

MAIN RESULTS

Twenty-eight patients were randomized to group P and 26 patients to group C. MAP was higher in group P than in group C (92 ± 2 vs 82 ± 2 mm Hg, mean ± SD, P< .001). The number of hypotensive episodes per patient was higher in group C compared with group P (9 [0-39] vs 1 [0-10], median [extremes], P< .01), but the number of hypotensive patients was similar between groups (19 [73%] vs 20 [71%], P= 1). The time to onset of the first hypotension was shorter in group C (3 [1-13] vs 15 [1-95] minutes, P= .004). The proportion of patients without hypotension (cumulative survival) was better in group P (P= .04). The number of hypertensive episodes per patient and the number of bradycardic episodes per patient were similar between groups (P= not significant).

CONCLUSION

Prophylactic phenylephrine infusion is an effective method of reducing SA-induced hypotension in the elderly. Compared with a control group, it delays the time to onset of hypotension and decreases the number of hypotensive episodes per patient. More data are needed to evaluate clinical outcomes of such a strategy.