Continuous spinal anesthesia with a microcatheter and low-dose bupivacaine decreases the hemodynamic effects of centroneuraxis blocks in elderly patients

Continuous spinal anaesthesia for partial gastrectomy in an adult patient with unrepaired tetralogy of Fallot

Correction of tetralogy of Fallot during infancy usually eliminates the risks associated with general anaesthesia. In rare cases of uncorrected defects persisting into adulthood, anaesthetic management during non-cardiac surgery may therefore be challenging. We describe the use of continuous spinal anaesthesia to successfully circumvent the operative risk of major abdominal surgery in an adult patient with uncorrected tetralogy of Fallot.

Comparison of dexmedetomidine vs. remifentanil combined with sevoflurane during radiofrequency ablation of hepatocellular carcinoma: a randomized controlled trial

BACKGROUND

Remifentanil is widely used for ultrasound-guided percutaneous radiofrequency ablation (RFA) of small hepatocellular carcinoma (HCC). We determined whether dexmedetomidine could be an alternative to remifentanil for RFA of HCC under general anesthesia with sevoflurane.

METHODS

We prospectively randomized patients scheduled to undergo RFA for HCC to a dexmedetomidine (DEX) group or remifentanil (REMI) group (47 patients each). In the DEX group, a bolus infusion (0.4 μg kg^- 1) was started 15 min before anesthesia induction and continued at 0.2 μg kg^- 1 h^- 1 until 10 min before the end of surgery. In the REMI group, 3 μg kg^- 1 h^- 1 of remifentanil was administered from 15 min before anesthesia induction to the end of the surgery. The primary endpoint was postoperative pain intensity. Secondary endpoints included analgesic requirement, postoperative liver function, patient comfort, and hemodynamic changes. Group allocation was concealed from patients and data analysts but not from anesthesiologists.

RESULTS

Postoperative pain intensity, analgesic consumption, comfort, liver function, and time to emergence and extubation did not differ between the two groups. Heart rate, but not mean arterial pressure, was significantly lower in the DEX group than in the REMI group, at 1 min after intubation and from 30 min after the start of the surgery until anesthesia recovery. Sevoflurane concentration and dosage were significantly lower in the DEX group than in the REMI group.

CONCLUSION

During RFA for HCC, low-dose dexmedetomidine reduced the heart rate and need for inhalational anesthetics, without exacerbating postoperative discomfort or liver dysfunction. Although it did not exhibit outstanding advantages over remifentanil in terms of pain management, dexmedetomidine could be a safe alternative adjuvant for RFA under sevoflurane anesthesia.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-OPC-15006613 . Registered on 16 June 2015.

Continuous spinal anaesthesia: A retrospective analysis of 318 cases

Background and Aims:

Continuous spinal anaesthesia (CSA) is an underutilised anaesthetic technique. Our objectives were to evaluate the use of CSA in our institution, its efficacy, ease to use and safety.

Methods:

This was a retrospective analysis conducted in a tertiary centre. Records of all patients who underwent surgery and received CSA between December 2008 and July 2017 were reviewed. Their demographic profiles, type and duration of surgery were analysed. The outcomes measured were the success of CSA, technical evaluation and difficulties encountered, intraoperative haemodynamics, usage of vasopressors and any reported complications. Statistical analysis was done using Chi-square test.

Results:

Three hundred and eighteen patients (94%) successfully underwent surgery using CSA. Twenty cases (6%) had failed CSA, of which five of them had CSA insertion failure, while the rest failed to complete the operation under CSA, thus requiring conversion to general anaesthesia. Patients who have had an initial intrathecal local anaesthetic (LA) volume ≥1.5 ml had higher odds (odds ratio (OR) 2.78; 95% confidence interval [CI], 1.70–4.57) of developing hypotension compared to those who had <1.5 ml (P < 0.001). There were no reported post-dural puncture headache, neurological sequelae or infection.

Conclusion:

CSA is a useful anaesthetic technique with low failure rate. The key to achieving haemodynamic stability is by giving a small initial bolus, then titrating the block up to required height using aliquots of 0.5 ml of intrathecal LA through the catheter.

Comparison of two doses of hypobaric bupivacaine in unilateral spinal anesthesia for hip fracture surgery: 5 mg versus 7.5 mg

Introduction

Hip fracture is a frequent and severe disease. Its prognosis depends on the perioperative hemodynamic stability which can be preserved by the unilateral spinal anesthesia especially with low doses of local anesthetics. This study aims to compare the efficacy and hemodynamic stability of two doses of hypobaric bupivacaine (7.5 mg vs 5 mg) in unilateral spinal anesthesia.

Methods

In this prospective, randomized, double-blind study, 108 patients scheduled for hip fracture surgery under unilateral spinal anesthesia were enrolled to receive either 5 mg (group 1) or 7.5 mg (group 2) of hypobaric bupivacaine. Spinal anesthesia was performed in lateral position. Patients’ socio-demographic characteristics, hemodynamic profile, sensory and motor blocks parameters were recorded.

Results

Both groups were comparable regarding to demographic data. Two cases of failure occurred in group 1 and one case in group 2 corresponding to a comparable efficiency rates (96.29% and 98.14% respectively; p = 0.5). A higher mean onset and lower mean regression times of sensory block were significantly noted in group 1 (7.79±3.76 min vs 5.75±2.35 min, p < 0.001 and 91.29±31.55 min vs 112.77±18.77 min, p <0.001 respectively). Incidence of bilateralization (29.62% vs 87.03%, p < 0.001), incidence of hypotensive episodes (59.25% vs 92.59%, p < 0.001) and vascular loading (1481.48±411.65 ml vs 2111.11±596.10 ml, p < 0.001) were significantly higher in group 2.

Conclusion

The dosage of 5mg of hypobaric bupivacaine in unilateral spinal anesthesia is as effective as the dosage of 7.5 mg with lower bilateralization incidence and better hemodynamic stability.

Pharmacodynamic analysis of target-controlled infusion of propofol in patients with hepatic insufficiency

The effect of liver dysfunction on target-controlled infusion (TCI) of propofol remains poorly documented. The pharmacodynamic performance of propofol TCI was evaluated in a cohort of Chinese patients with hepatic insufficiency. Fifty-three patients with hepatic insufficiency were enrolled in the current prospective, observational study. Anesthesia was induced with propofol via TCI to a plasma concentration of 3 µg/ml. Following loss of consciousness (LOC), fentanyl and cisatracurium were administered. Pharmacodynamic parameters were recorded during TCI, including time to LOC, bispectral index (BIS), heart rate (HR) and blood pressure. Patients were divided into two groups based on model of end stage liver disease (MELD) score: Those with a MELD score of ≤9 and those with a MELD score of ≥10. BIS, mean arterial pressure and HR were demonstrated to vary according to time, but were not affected by liver dysfunction. Hypotension was prominent in patients with a MELD score of ≥10 30 min after induction. The proportion of bradycardia and hypotension at the other time points was not significantly different between MELD scores of ≤9 and ≥10. Notably, no bradycardia was observed in MELD of ≥10. Thus, bradycardia and hypotension was observed in patients with hepatic insufficiency over time, although patients with different severities of hepatic insufficiency did not present with different depths of anesthesia. TCI of propofol to 3 µg/ml may be not suitable for patients with hepatic insufficiency, particularly those with severe liver dysfunction. Predictive concentrations (Cp) of TCI propofol requires further investigation and adjustment in patients with hepatic insufficiency (trial registration no. ChiCTR-OCH-12002255).

Satisfactory spinal anesthesia with a total of 1.5 mg of bupivacaine for transurethral resection of bladder tumor in an elderly patient

Spinal anesthesia is popular for endoscopic urological surgery. Many patients undergoing urological surgery are elderly. It is important to limit the dose to reduce any resultant hemodynamic effect. We present a case in which incremental administration of 0.1 % bupivacaine up to 1.5 mg was sufficient to produce satisfactory spinal anesthesia for transurethral resection of bladder tumor (TURBT).

Continuous Spinal Anaesthesia for Endovascular Repair of Abdominal Aortic Aneurysm in High-Risk Patient

Endovascular aneurysm repair (EVAR) is increasingly being used in abdominal aortic aneurysm (AAA) treatment, as it is less invasive than open surgery. A wide range of anaesthetic types, such as general anaesthesia, neuroaxial blocks and local anaesthesia, have been shown to be appropriate for the EVAR procedure. In the continuous spinal anaesthesia (CSA) method, the local anaesthetic may be titrated through a catheter placed in the subarachnoid space, allowing better control of the anaesthetic level and a reduction in potential haemodynamic side effects. Our aim is to present CSA as a successful anaesthetic technique for EVAR in an AAA patient with severe co-existing diseases.

Anesthetic management for lower limb fracture in severe aortic valve stenosis and fat embolism: a case report and review of literature

Introduction:

Anesthesia in severe aortic stenosis, which describes a valve surface area less than 1 cm², can result in rapid clinical deterioration and patient mortality. These patients may require treatment for aortic stenosis before any surgical intervention. In suitable patients percutaneous balloon aortic valvutomy appears to carry lower risk, but in emergency situations, it is important to determine which kind of anesthesia technique has the lowest risk for these patients, without any cardiac intervention.

Case Presentation:

In this case report, we present a patient who had tibia and fibula fractures and a symptomatic severe critical aortic stenosis which was diagnosed during a preoperative visit. The patient had exertional dyspnea, palpitations and fainting history, but he had not received any medical therapy before the present admission. During hospitalization and preoperative evaluation, a fat embolism occurred and the patient was admitted to the intensive care unit. Immediately after his recovery, we successfully managed the tibia and fibula fracture fixation without any cardiac intervention.

Conclusions:

Our anesthesia method was sciatic and femoral nerve block under double ultrasonic and nerve stimulator guidance.

Comparison of unilateral spinal and continous spinal anesthesia for hip surgery in elderly patients

BACKGROUND

Continous spinal anesthesia (CSA) and frequently unilateral spinal anesthesia (USpA) are usually preferred for lower extremity surgeries. In this study, we aimed to compare the effects of these anesthetic techniques, on hemodynamic parameters, quality of anesthesia and complications in elderly patients undergoing hip surgeries.

METHODS

Forty patients aged 65 years and older, assigned to receive either CSA or USpA with 7.5 mg (1.5 cc) 0.5% hyperbaric bupivacaine initially. In CSA group, additional doses of 2.5 mg bupivacaine were applied until sensory block reach to T10. Maximum sensorial block level, time to reach the level of T10 (defined as onset time) and to regress to T12, hemodynamic parameters and ephedrine requirements were recorded peroperatively and during 2 h postoperatively.

RESULTS

Hemodynamic parameters, ephedrine requirements and regression of sensory block by two levels were similar in two groups. The onset time of anesthesia was significantly longer in USpA group than CSA group. Neuraxial anesthesia had to be converted to general anesthesia in 5 patients (25%) in CSA group and 1 patient (5%) in USpA group.

CONCLUSIONS

We conclude that both USpA and CSA techniques have similar effects in elderly high risk patients. On the other hand, USpA is more preferable for surgeries with shorter durations due to its low cost and high success rate.

The comparison of levobupivacaine in continuous or single dose spinal anesthesia for transurethral resection of prostate surgery

BACKGROUND

The aim of the study is to compare the efficacy of levobupivacaine induced continuous spinal anesthesia (CSA) versus single dose spinal anesthesia (SDSA) in patients who are planned to undergo transurethral prostate resection.

METHODS

Sixty years or older, ASA I-II or III, 50 patients were included in the study. 12.5mg 0.5% levobupivacaine were administered intrathecally in SDSA group. In CSA group, initially 2mL of 0.25% levobupivacaine were administered through spinal catheter. In order to achieve sensory block level at T10 dermatome, additional 1mL of 0.25% levobupivacaine were administered through the catheter in every 10min. Hemodynamic parameters and block characteristics were recorded. Preoperative and postoperative blood samples of the patients were drawn to determine plasma cortisone and plasma epinephrine levels.

RESULTS

CSA technique provided better hemodynamic stability compared to SDSA technique particularly 90min after intrathecal administration. The rise in sensory block level was rapid and the time to reach surgical anesthesia was shorter in SDSA group. Motor block developed faster in SDSA group. In CSA group, similar anesthesia level was achieved by using lower levobupivacaine dose and which was related to faster recovery. Although, both techniques were effective in preventing surgical stress respond, postoperative cortisone levels were suppressed more in SDSA group.

CONCLUSION

CSA technique with 0.25% levobupivacaine can be used as a regional anesthesia method for elderly patients planned to have TUR-P operation.

Hemodynamic profile of target-controlled spinal anesthesia compared with 2 target-controlled general anesthesia techniques in elderly patients with cardiac comorbidities

BACKGROUND AND OBJECTIVES

The impact of anesthesia techniques in patients experiencing hip fracture is controversial. This study compares the effects on blood pressure of 3 anesthesia techniques that are considered safe for the elderly.

METHODS

Forty-five patients older than 75 years, with American Society of Anesthesiologists physical status III or IV, with cardiac comorbidities, and undergoing surgery for hip fracture, were randomized to receive continuous spinal anesthesia (CSA), propofol target-controlled infusion (TCI), or sevoflurane (SEVO). In CSA patients, a T10 metameric level target was achieved by titration of 2.5 mg of bupivacaine boluses. In patients on TCI and SEVO, a bispectral value target of around 50 guided the concentration of propofol or sevoflurane. Analgesia in the TCI and SEVO groups was provided with remifentanil. Hypotension was defined as a 30% decrease in mean arterial pressure and was treated with an intravenous bolus of ephedrine.

RESULTS

The number of hypotension episodes was lower in the CSA group: 0 (range, 0-6) versus 11.5 (range, 1-25) in the TCI group and 10 (range, 1-23) in the SEVO group (P < 0.001). Both TCI and SEVO patients needed more ephedrine compared with CSA patients (30.5 [15.5], 26 [23], and 1.5 [2.5] mg, respectively, P < 0.001). The maximal decrease in mean arterial pressure was lower in the CSA group (26% [17%]) compared with that in the TCI group (47% [8%]) and the SEVO group (46% [12%]; P < 0.001).

CONCLUSIONS

In elderly patients, spinal anesthesia using titrated doses of bupivacaine provided better blood pressure stability than propofol or sevoflurane anesthesia.

[Pulmonary hypertension and femoral neck fracture: interest of continuous spinal anaesthesia]

Anaesthetic management of patients with pulmonary hypertension is challenging and alternatives to general anaesthesia are encouraged. We report anaesthetic management of two patients with pulmonary hypertension admitted for femoral neck fracture. In order to reduce the risk of right-sided heart failure and systemic hypotension, it was decided to operate the patients under continuous spinal anaesthesia. Anaesthesia was induced with excellent hemodynamic tolerance. Quality and extension of the block was correct and allowed surgery. No postoperative complication was observed. These cases suggest that continuous spinal anaesthesia may be considered for the management of patients with pulmonary hypertension undergoing femoral neck fracture surgery.

Continuous spinal anesthesia

Continuous spinal anesthesia (CSA) is an underutilized technique in modern anesthesia practice. Compared with other techniques of neuraxial anesthesia, CSA allows incremental dosing of an intrathecal local anesthetic for an indefinite duration, whereas traditional single-shot spinal anesthesia usually involves larger doses, a finite, unpredictable duration, and greater potential for detrimental hemodynamic effects including hypotension, and epidural anesthesia via a catheter may produce lesser motor block and suboptimal anesthesia in sacral nerve root distributions. This review compares CSA with other anesthetic techniques and also describes the history of CSA, its clinical applications, concerns regarding neurotoxicity, and other pharmacologic implications of its use. CSA has seen a waxing and waning of its popularity in clinical practice since its initial description in 1907. After case reports of cauda equina syndrome were reported with the use of spinal microcatheters for CSA, these microcatheters were withdrawn from clinical practice in the United States but continued to be used in Europe with no further neurologic sequelae. Because only large-bore catheters may be used in the United States, CSA is usually reserved for elderly patients out of concern for the risk of postdural puncture headache in younger patients. However, even in younger patients, sometimes the unique clinical benefits and hemodynamic stability involved in CSA outweigh concerns regarding postdural puncture headache. Clinical scenarios in which CSA may be of particular benefit include patients with severe aortic stenosis undergoing lower extremity surgery and obstetric patients with complex heart disease. CSA is an underutilized technique in modern anesthesia practice. Perhaps more accurately termed fractional spinal anesthesia, CSA involves intermittent dosing of local anesthetic solution via an intrathecal catheter. Where traditional spinal anesthesia involves a single injection with a somewhat unpredictable spread and duration of effect, CSA allows titration of the block level to the patient's needs, permits a spinal block of indefinite duration, and can provide greater hemodynamic stability than single-injection spinal anesthesia.

Anaesthesia and analgesia: contribution to surgery, present and future

Anaesthetists provide comprehensive perioperative medical care to patients undergoing surgical and diagnostic procedures, including postoperative intensive care when needed. They are involved in the management of perioperative acute pain as well as chronic pain. This manuscript considers some of the recent advances in modern anaesthesia and their contribution to surgery, from the basic mechanisms of action, to the delivery systems for general and regional anaesthesia, to the use of new drugs and new methods of monitoring. It assesses the resulting progress in acute and chronic pain services and looks at patient safety and risk management. It speculates on directions that may shape its future contributions to the management of the patient undergoing surgery.

Spinal anaesthesia with a micro-catheter in high-risk patients undergoing colorectal cancer and other major abdominal surgery

Extended spinal anaesthesia using a spinal micro-catheter was used as a primary method of anaesthesia for elective colorectal cancer surgery in 68 high risk patients over a 14-year period in our institution. The technique was also useful in eight elective and 13 emergency abdominal surgeries. All patients suffered from severe chronic obstructive airway disease requiring multiple inhalers and drugs (ASA III). Thirty nine of these patients also suffered from angina, myocardial infarction, diabetes and other systemic diseases (ASA IV). Surgery included right hemicolectomy, left hemicolectomy, total colectomy, sigmoid colectomy, Hartman's resection, anterior resection of rectum, abdominoperineal resection, cholecystectomy (open and laparoscopic) and obstructed inguinal hernia requiring laparotomy. Spinal anaesthesia was performed under strict aseptic conditions with a 22 gauge spinal needle with a mixture consisting of 2.75ml of 0.5% heavy bupivacaine and 0.25ml of fentanyl (25microg). This was followed by placement of a spinal micro-catheter and the duration of anaesthesia was extended by intermittent injection of 0.5% isobaric bupivacaine. Brief hypotension occurred in 12.4% of patients during the establishment of anaesthetic block height to T6-7 and was duly treated with intravenous administration of fluid and ephedrine hydrochloride. Good anaesthesia resulted in all patients except for brief discomfort in some patients during hemicolectomy surgery possibly due to the dissection and traction on the peritoneum causing irritation to the diaphragm. The use of sedation was avoided. General anaesthesia was administered in one patient and this patient required postoperative ventilation and cardiovascular support in the Intensive Care Unit. The spinal micro-catheter was removed at the end of surgery. Postoperative pain relief was obtained by administering intravenous morphine through a patient controlled analgesia machine in the critical care ward area (High Dependency Unit). There was a low incidence of minor postoperative side effects such as nausea (14.6%), vomiting (7.9%), minor post dural puncture headache (5.6%) and pruritus (5.6%). We conclude that spinal anaesthesia with a micro-catheter may be used as a primary method of anaesthesia for colorectal cancer surgery and other major abdominal surgery in high-risk patients for whom general anaesthesia would be associated with higher morbidity and mortality.

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.

Rachianesthésie continue pour fracture du col fémoral chez deux patients présentant un rétrécissement aortique serré

Neuraxial blockade is usually not recommended in patients with aortic stenosis. However, neuroaxial blockade techniques such as continuous spinal or epidural anaesthesia can be tailored to minimize potentially dramatic consequences of decrease in systemic vascular resistance, often encountered after standard single shot spinal anaesthesia. We report the cases of two severe aortic stenosis patients (aortic valve area<0.5 cm2) that underwent hip surgery under continuous spinal anaesthesia. Small doses of isobaric 0.25% bupivacaine titrated to limit total dose below 5 mg, injected through the intrathecal catheter allowed the control of haemodynamic parameters. No clinical complication occurred in these two patients.

Isobaric bupivacaine via spinal catheter for hip replacement surgery: ED50 and ED95 dose determination

BACKGROUND

Continuous spinal anaesthesia with spinal catheters allows incremental dosing of the local anaesthetic and, consequently, less haemodynamic change. However, little is known about the required doses. Therefore, we designed a study to assess the local anaesthetic doses of isobaric bupivacaine which were effective in 50% (ED50) and 95% (ED95) of patients undergoing hip replacement surgery.

METHODS

Forty-eight patients undergoing hip replacement surgery were randomly allocated to one of six possible groups of eight patients to receive 6, 7, 8, 9, 10 or 12 mg of isobaric bupivacaine in a double-blind manner. The ED50 and ED95 values were calculated by a logistic regression model. The position of the spinal catheter tip was confirmed by X-rays.

RESULTS

The ED50 and ED95 values were 7.1 mg (95% confidence interval, 6.0-8.4) and 12.3 mg (95% confidence interval, 8.9-15.7), respectively. The location of the tip of the intrathecal catheter had no effect on local anaesthetic requirements. Eight patients required ephedrine after anaesthesia induction and a further 11 patients required ephedrine for correction of hypotension during surgery.

CONCLUSION

The observed ED50 and ED95 values may guide us to use small doses of isobaric bupivacaine for hip replacement surgery. Hypotension is still possible even if low doses of isobaric bupivacaine are used.

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.

The Mechanical Properties of Continuous Spinal Small-Bore Catheters

Continuous spinal anesthesia (CSA) has a nearly 100-yr history. In situations of difficult removal of a CSA small-bore catheter, mechanical properties of the different catheters might be important, because breakage could occur. We compared 5 different CSA small-bore catheters, 22- to 28-gauge from 3 manufacturers, for tensile strength, tensile stress, distension, and yield strength. Maximal tensile strength is the force applied before breakage of the catheter. The material characteristics of different CSA small-bore catheters for maximal tensile strength were: 22-gauge = 29.56 +/- 1.56 (mean +/- sd) Newton (N), 24-gauge = 16.77 +/- 1.61 N, 25-gauge = 9.20 +/- 0.48 N, 27-gauge = 4.61 +/- 0.25 N, 28-gauge = 5.07 +/- 0.59 N at room temperature. A strong correlation between maximal tensile strength and the outer diameter (r = 0.957, P < 0.001) and maximal tensile strength and the wall thickness (r = 0.9, P < 0.001) was observed. Although extrapolation from experimental studies to clinical routine should be made with care, our data suggest that catheters with higher-strength characteristics may reduce the risk of catheter breakage in patients, although clinical correlations are lacking.

Continuous spinal anaesthesia: what's new and what's not

Continuous spinal anaesthesia combines the advantages of single-dose spinal anaesthesia, rapid onset and a high degree of success, with those of a continuous technique. The introduction of micro-catheters invigorated interest in the technique and allowed its expansion to additional populations and surgical procedures. However, multiple cases of cauda equina syndrome associated with micro-catheters and (primarily) hyperbaric lidocaine solution led to withdrawal of micro-catheters from the US market, casting doubt over the safety of continuous spinal anaesthesia as a whole. A decade after these events it is possible to look back at the experience with continuous spinal anaesthesia for operative anaesthesia and postoperative analgesia and to compare it with the available alternatives. From this perspective, continuous spinal anaesthesia remains a useful and safe technique. Future research should focus on the comparison of continuous spinal anaesthesia with the combined spinal/epidural technique and the use of newer spinal agents.

Continuous spinal anesthesia for cesarean section in a parturient with severe recurrent peripartum cardiomyopathy

The anesthetic management of labor and delivery in patients with peripartum cardiomyopathy is not well defined. Using continuous spinal anesthesia in such a rare clinical situation has not been previously reported. A patient with recurrent peripartum cardiomyopathy presented in congestive heart failure for emergent cesarean section. Continuous spinal anesthesia was successfully employed as the anesthetic technique for the procedure. In addition, it also markedly reduced the patient's symptoms. Continuous spinal anesthesia is a reliable, rapidly titratable technique, which provides excellent analgesia with minimal undesirable hemodynamic changes for patients with peripartum cardiomyopathy undergoing cesarean delivery.

Continuous spinal anesthesia/analgesia vs. single-shot spinal anesthesia with patient-controlled analgesia for elective hip arthroplasty

BACKGROUND

In total hip replacement surgery several anesthesiological techniques can be used. In this study we compared continuous spinal anesthesia (CSA) and postoperative analgesia vs. single-shot spinal anesthesia (SPA) and postoperative patient-controlled intravenous analgesia with morphine (SPA).

METHODS

In a prospective randomized study, 68 patients, ASA I-III, between 50 and 85 years of age were allocated to these two groups. Quality of analgesia, hemodynamic stability and technical difficulties, as well as incidence of postoperative nausea and vomiting (PONV) and post dural puncture headache (PDPH), were recorded during a 24-h period.

RESULTS

Visual analog scale (VAS) scores were significantly lower in the CSA group from 3 h post operation (P < 0.05). Mean arterial pressure dropped by 21 +/- 11 mmHg in the CSA group and 29 +/- 14 in the SPA group during induction (P < 0.05). Technical difficulties and incidence of PDPH were similar in both groups. Postoperative nausea and vomiting was lower in the CSA group (P < 0.05).

CONCLUSIONS

Continuous spinal anesthesia/analgesia is a very practicable method providing better postoperative analgesia and better hemodynamic stability during anesthesia induction than SPA followed by morphine PCA analgesia after total hip replacement surgery.

Cricoid yoke: the effect of surface area and applied force on discomfort experienced by conscious volunteers

BACKGROUND AND OBJECTIVE

The application of cricoid force is central to techniques that reduce the risk of gastric regurgitation and the subsequent pulmonary aspiration associated with obstetric and emergency anaesthesia. The discomfort associated with cricoid force in awake preoperative patients increases the incidence of coughing, struggling and pain during induction of anaesthesia. This study determined if increasing the surface area of a cricoid yoke reduced the associated discomfort in volunteers.

METHODS

Fifty volunteers participated in a randomized single-blinded study. The cricoid yoke was positioned using standard anatomical landmarks and forces of 10, 20, 30 and 40 N were applied in a random order for 20s, using two different yoke attachments with surface areas of 3 and 10 cm2. A rest of 30s was allowed between the application of forces. Discomfort was graded by volunteers on a scale from 0 to 10 (0: no discomfort; 10: worse discomfort imaginable). A score of 10 was allocated if the volunteers could not tolerate the applied force for 20s.

RESULTS

Median scores for the small yoke were always higher than those for the large yoke at each force. There were significant differences between the scores for the small and large yokes at 10 and 20 N (P < 0.001) and 30 N (P = 0.0233), but there was no significant difference at 40 N.

CONCLUSIONS

The larger yoke was tolerated better by volunteers when clinically relevant cricoid forces were applied.

Tracheal intubation without muscle relaxants: remifentanil or alfentanil in combination with propofol

BACKGROUND AND OBJECTIVE

In some situations, the use of muscle relaxants (neuromuscular blocking drugs) are undesirable or contraindicated. We compared intubating conditions without muscle relaxants in premedicated patients receiving either alfentanil 40 microg kg(-1) or remifentanil 2, 3 or 4 microg kg(-1) followed by propofol 2 mg kg(-1).

METHODS

In a randomized, double-blind study, 80 healthy patients were assigned to one of four groups (n = 20). After intravenous atropine, alfentanil 40 microg kg(-1) or remifentanil 2, 3 or 4 microg kg(-1) were injected over 90 s followed by propofol 2 mg kg(-1). Ninety seconds after administration of the propofol, laryngoscopy and tracheal intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of lung ventilation, jaw relaxation, laryngoscopy, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff.

RESULTS

Seven patients who received remifentanil 2 microg kg(-1) and one patient who received remifentanil 3 microg kg(-1) could not be intubated at the first attempts. Excellent intubating conditions (jaw relaxed, vocal cords open and no movement in response to tracheal intubation and cuff inflation) were observed in those who received either alfentanil 40 microg kg(-1) (45% of patients) or remifentanil in doses of 2 microg kg(-1) (20%), 3 microg kg(-1) (75%) or 4 microg kg(-1) (95%). Overall, intubating conditions were significantly better (P < 0.05), and the number of patients showing excellent conditions were significantly higher (P < 0.05) in patients who received remifentanil 4 microg kg(-1) compared with those who received alfentanil 40 microg kg(-1) or remifentanil 2 microg kg(-1). No patient needed treatment for hypotension or bradycardia.

CONCLUSIONS

Remifentanil 4 microg kg(-1) and propofol 2 mg kg(-1) administered in sequence intravenously provided good or excellent conditions for tracheal intubation in all patients without the use of muscle relaxants.

Stability of the LMA-ProSeal and standard laryngeal mask airway in different head and neck positions: a randomized crossover study

BACKGROUND AND OBJECTIVE

The LMA-ProSeal laryngeal mask airway is a new laryngeal mask airway with a modified cuff and drainage tube. We compared oropharyngeal leak pressure, intracuff pressure and anatomical position (assessed fibreoptically) for the Size 5 LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway in different head-neck positions and using different intracuff inflation volumes.

METHODS

Thirty paralysed anaesthetized adult male patients were studied. The LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway were inserted into each patient in random order. The oropharyngeal leak pressure, intracuff pressure, and anatomical position of the airway tube and drainage tube (LMA-ProSeal laryngeal mask airway only) were documented in four head and neck positions (neutral first, then flexion, extension and rotation in random order), and at 0-40 mL cuff volumes in the neutral position in 10 mL increments.

RESULTS

Compared with the neutral position, the oropharyngeal leak pressure for both the LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway was higher in flexion and rotation (all P < or = 0.02), but lower in extension (all P < or = 0.01). Changes in head-neck position did not alter the anatomical position of the airway tube or the drainage tube. The oropharyngeal leak pressure was always higher for the LMA-ProSeal laryngeal mask airway (all P < or = 0.005) and anatomical position better for the classic laryngeal mask airway (all P < or = 0.04).

CONCLUSIONS

The anatomical position of the LMA-ProSeal and the classic laryngeal mask airway is stable in different head-neck positions, but head-neck flexion and rotation are associated with an increase, and head-neck extension a decrease, in oropharyngeal leak pressure and intracuff pressure. The Size 5 LMA-ProSeal laryngeal mask airway is capable of forming a more effective seal than the Size 5 classic laryngeal mask airway in males.

Breathing pattern and workload during automatic tube compensation, pressure support and T-piece trials in weaning patients

BACKGROUND AND OBJECTIVE

Automatic tube compensation has been designed as a new ventilatory mode to compensate for the non-linear resistance of the endotracheal tube. The study investigated the effects of automatic tube compensation compared with breathing through a T-piece or pressure support during a trial of spontaneous breathing used for weaning patients from mechanical ventilation of the lungs.

METHODS

Twelve patients were studied who were ready for weaning after prolonged mechanical ventilation (10.2 +/- 8.4 days) due to acute respiratory failure. Patients with chronic obstructive pulmonary disease were excluded. Thirty minutes of automatic tube compensation were compared with 30 min periods of 7 cmH2O pressure support and T-piece breathing. Breathing patterns and workload indices were measured at the end of each study period.

RESULTS

During T-piece breathing, the peak inspiratory flow rate (0.65 +/- 0.20 L s(-1)) and minute ventilation (8.9 +/- 2.7L min(-1)) were lower than during either pressure support (peak inspiratory flow rate 0.81 +/- 0.25 L s(-1) minute ventilation 10.2 +/- 2.3 L min(-1), respectively) or automatic tube compensation (peak inspiratory flow rate 0.75 +/- 0.26L s(-1); minute ventilation 10.8 +/- 2.7 L min(-1)). The pressure-time product as well as patients' work of breathing were comparable during automatic tube compensation (pressure-time product 214.5 +/- 104.6 cmH2O s(-1) min(-1), patient work of breathing 1.1 +/- 0.4 J L(-1)) and T-piece breathing (pressure-time product 208.3 +/- 121.6 cmH2O s(-1) min(-1), patient work of breathing 1.1 +/- 0.4 J L(-1)), whereas pressure support resulted in a significant decrease in workload indices (pressure-time product 121.2 +/- 64.1 cmH2O s(-1) min(-1), patient work of breathing 0.7 +/- 0.4 J L(-1)).

CONCLUSIONS

In weaning from mechanical lung ventilation, patients' work of breathing during spontaneous breathing trials is clearly reduced by the application of pressure support 7 cmH2O, whereas the workload during automatic tube compensation corresponded closely to the values during trials of breathing through a T-piece.

Anaesthetic agents in adult day case surgery

This study reports a review of all comparative published studies of adult day case anaesthesia in the English language up to December 2000. Ten databases were searched using appropriate keywords and data were extracted in a standardized fashion. One hundred-and-one published studies were examined. Recovery measurements were grouped as early, intermediate, late, psychomotor and adverse effects. With respect to induction of anaesthesia, propofol was superior to methohexital, etomidate and thiopental, but equal to sevoflurane and desflurane. Desflurane and sevoflurane were both superior to thiopental. There was no detectable difference between sevoflurane and isoflurane. With respect to the maintenance of anaesthesia, isoflurane and halothane were the worst. There were no significant differences between propofol, desflurane, sevoflurane and enflurane. Propofol is the induction agent of choice in day case patients. The use of a propofol infusion and avoidance of nitrous oxide may help to reduce postoperative nausea and vomiting.

Prediction of difficult tracheal intubation

BACKGROUND AND OBJECTIVE

Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value.

METHODS

A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification.

RESULTS

Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5cm or a sternomental distance <12.5cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%.

CONCLUSIONS

The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.

Remifentanil versus alfentanil in total intravenous anaesthesia for day case surgery

BACKGROUND AND OBJECTIVE

We assessed the intraoperative haemodynamic responses and recovery profiles of total intravenous anaesthesia with remifentanil and alfentanil for outpatient surgery.

METHODS

Patients in Group 1 (n = 20) received alfentanil 20 microg kg(-1) followed by 2 microg kg(-1) min(-1) intravenously; patients in Group 2 (n = 20) received remifentanil 1 microg kg(-1) followed by 0.5 microg kg(-1) min(-1) intravenously. Both groups then received propofol 2 mg kg(-1) followed by 9 mg kg(-1) h(-1) intravenously. Five minutes after skin incision, infusion rates were decreased, and at the end of surgery, all infusions were discontinued. Early recovery was assessed by the Aldrete score, whereas intermediate recovery was assessed with the postanaesthetic discharge scoring system (PADS).

RESULTS

Perioperative arterial pressure was similar in both groups; heart rate was lower in Group 2 (P < 0.05). The times to spontaneous and adequate respiration, response to verbal commands, extubation and times for Aldrete score > or = 9 were shorter in Group 2 patients (P < 0.05). Pain scores were higher in Group 2 patients (P < 0.05). Overall times for postanaesthetic discharge scores > or = 9 were similar.

CONCLUSIONS

Early recovery of patients after day surgery is significantly shorter after total intravenous anaesthesia with remifentanil compared with that with alfentanil but postoperative pain management must be planned ahead.

Effects of different doses of oral ketamine for premedication of children

BACKGROUND AND OBJECTIVE

A need exists for a safe and effective oral preanaesthetic medication for use in children undergoing elective surgery. The study sought to define the dose of oral ketamine that would facilitate induction of anaesthesia without causing significant side-effects.

METHODS

We studied 80 children undergoing elective surgery under general anaesthesia who received oral ketamine 4, 6 or 8 mg kg(-1) in a prospective, randomized, double-blind placebo controlled study. We compared the reaction to separation from parents, transport to the operating room, the response to intravenous cannula insertion and application of an anaesthetic facemask, the induction of anaesthesia and recovery from anaesthesia.

RESULTS

In the group receiving ketamine 8 mg kg(-1), the children were significantly calmer than those of the other groups, and anaesthesia induction was more comfortable. Recovery from anaesthesia was longer in the group receiving ketamine 8 mg kg(-1) compared with the other groups, but no differences between the groups were observed after 2 h in the recovery room.

CONCLUSIONS

It is concluded that oral ketamine 8 mg kg(-1) is an effective oral premedication in inpatient children undergoing elective surgery.

Trendelenburg positioning after cardiac surgery: effects on intrathoracic blood volume index and cardiac performance

BACKGROUND AND OBJECTIVE

The efficacy of the Trendelenburg position, a common first step to treat suspected hypovolaemia, remains controversial. We evaluated its haemodynamic effects on cardiac preload and performance in patients after cardiac surgery.

METHODS

Twelve patients undergoing mechanical ventilation of the lungs who demonstrated left ventricular 'kissing papillary muscles' by transoesophageal echocardiography, thus suggesting hypovolaemia, were positioned 30 degrees head down for 15 min immediately after cardiac surgery. Cardiac output by thermodilution, central venous pressure, pulmonary artery occlusion pressure, left ventricular end-diastolic area by transoesophageal echocardiography and intrathoracic blood volume by thermo- and dye dilution were determined before, during and after this Trendelenburg manoeuvre.

RESULTS

Trendelenburg's manoeuvre was associated with increases in central venous pressure (9 +/- 2 to 12 +/- 3 mmHg) and pulmonary artery occlusion pressure (8 +/- 2 to 11 +/- 3 mmHg). The intrathoracic blood volume index increased slightly (dye dilution from 836 +/- 129 to 872 +/- 112 mL m(-2); thermodilution from 823 +/- 129 to 850 +/- 131 mL m(-2)) as did the left ventricular end-diastolic area index (7.5 +/- 2.1 to 8.1 +/- 1.7 cm2 m(-2)), whereas mean arterial pressure and the cardiac index did not change significantly. After supine repositioning, the cardiac index decreased significantly below baseline (3.0 +/- 0.6 versus 3.5 +/- 0.8 L min(-1) m(-2)) as did mean arterial pressure (76 +/- 12 versus 85 +/- 11 mmHg), central venous pressure (8 +/- 2 mmHg) and pulmonary artery occlusion pressure (6 +/- 4 mmHg). The intrathoracic blood volume index and left ventricular end-diastolic area index did not differ significantly from baseline.

CONCLUSIONS

Trendelenburg's manoeuvre caused only a slight increase of preload volume, despite marked increases in cardiac-filling pressures, without significantly improving cardiac performance.

Anaesthetic and haemodynamic effects of continuous spinal versus continuous epidural anaesthesia with prilocaine

BACKGROUND AND OBJECTIVE

To compare, using prilocaine, the effects of continuous spinal anaesthesia (CSA) and continuous epidural anaesthesia (CEA) on haemodynamic stability as well as the quality of anaesthesia and recovery in patients undergoing transurethral resection of the prostate gland.

METHODS

Thirty patients (>60 yr) were randomized into two groups. Prilocaine, 2% 40 mg, was given to patients in the CSA group, and prilocaine 1% 150mg was given to patients in the CEA group. Incremental doses were given if the level of sensory block was lower than T10 or if needed during surgery.

RESULTS

There was a significant decrease in mean arterial pressure in Group CEA compared with Group CSA (P < 0.01). The decrease in heart rate in Group CSA occurred 10 min after the first local anaesthetic administration and continued through the operation (P < 0.05). The level of sensory anaesthesia was similar in both groups. The times to reach the level of T10 and the upper level of sensory blockade (Tmax) were 18.0 +/- 4.7 and 25.3 +/- 7.0 min in Groups CSA and CEA, respectively, and were significantly longer in Group CEA. The duration of anaesthesia was 76.8 +/- 4min and was shorter in Group CSA (P < 0.01).

CONCLUSIONS

Spinal or epidural anaesthesia administered continuously was reliable in elderly patients undergoing transurethral resection of the prostate. Continuous spinal anaesthesia had a more rapid onset of action, produced more effective sensory and motor blockade and had a shorter recovery period. Prilocaine appeared to be a safe local anaesthetic for use with either continuous spinal anaesthesia or continuous epidural anaesthesia.

Cortical activity assessed by Narcotrend in relation to haemodynamic responses to tracheal intubation at different stages of cortical suppression and reflex control

BACKGROUND AND OBJECTIVE

Many anaesthesiologists still interpret haemodynamic responses as signs of insufficient cortical suppression. The aim was to illustrate how haemodynamics may only poorly reflect the level of cortical suppression and that electroencephalographic monitoring could indicate different relationships between cortical effects and haemodynamics.

METHODS

Anaesthesia was induced with thiopental (7 mg kg(-1)), and fentanyl (2 microg kg(-1)) with succinylcholine (1.5 mg kg(-1)) for neuromuscular blockade in the 11 patients of Group 1. In Group 2 (n = 15), thiopental (7 mg kg(-1)) and succinylcholine (1.5 mg kg(-1)) were given. In Group 3, the patients (n = 13) received thiopental (7 mg kg(-1)), fentanyl (2 microg kg(-1)) and cisatracurium (0.1 mg kg(-1)), and they were intubated 3 min later than the patients in Groups 1 and 2. We determined conventional electroencephalographic (EEG) variables and classified 14 EEG stages in real-time ranging from A (= 1), indicating full wakefulness, to F1 (= 14), at profound cortical suppression.

RESULTS

All groups had profound cortical suppression 45 s after thiopental administration, which rapidly decreased (EEG stage, 11 (6-13) versus 7 (2-13) at 4 min, P < 0.0001). Decreasing EEG stages were associated with increasing SEF 95, relative alpha and beta power and decreasing relative delta power. During tracheal intubation, profound cortical suppression remained unchanged in Groups 1 and 2. In Group 3, cortical suppression had decreased before laryngoscopy (P < 0.005). In Group 2, 11 patients had heart rate responses to tracheal intubation, whereas only two responded in Group 1 (P = 0.015) and three in Group 3 (P = 0.02). Thirteen patients in Group 2 had arterial pressure responses, and five in Group 1 (P = 0.038). Circulatory responses did not differ between Groups 1 and 3.

CONCLUSIONS

Electroencephalographic monitoring was suitable to indicate in real-time that haemodynamics only poorly reflect rapidly changing levels of cortical suppression, and how haemodynamics and cortical activity depend on the applied combination of hypnotic and analgesic drugs during anaesthesia induction with thiopental.

Increasing the injection volume by dilution improves the onset of motor blockade, but not sensory blockade of ropivacaine for brachial plexus block

BACKGROUND AND OBJECTIVE

Ropivacaine used for axillary plexus block provides effective motor and sensory blockade. Varying clinical dosage recommendations exist. Increasing the dosage by increasing the concentration showed no improvement in onset. We compared the behaviour of a constant dose of ropivacaine 150 mg diluted in a 30, 40 or 60 mL injection volume for axillary (brachial) plexus block.

METHODS

A prospective, randomized, observer-blinded study on patients undergoing elective hand surgery was conducted in a community hospital. Three groups of patients with a constant dose of ropivacaine 150 mg, diluted in 30,40 or 60 mL NaCl 0.9%, for axillary plexus blockade were compared for onset times of motor and sensory block onset by assessing muscle strength, two-point discrimination and constant-touch sensation.

RESULTS

Increasing the injection volume of ropivacaine 150 mg to 60 mL led to a faster onset of motor block, but not of sensory block, in axillary plexus block, compared with 30 or 40 mL volumes of injection.

CONCLUSIONS

The data show that the onset of motor, but not of sensory block, is accelerated by increasing the injection volume to 60 mL using ropivacaine 150 mg for axillary plexus block. This may be useful for a more rapid determination of whether the brachial plexus block is effective. However, when performing surgery in the area of the block, sensory block onset seems more important.

Intrathecal anesthesia

PURPOSE OF REVIEW

Development of new drugs and special techniques, as well as changes in health care organization have markedly influenced the use of spinal block and its indications. The present review overviews recent developments in local anesthetic drugs, side effects and special techniques for intrathecal anesthesia.

RECENT FINDINGS

Severe complications after spinal anesthesia are acceptably rare. The cardiovascular effects associated with sympathetic block are more frequent but may successfully be treated with volume expansion and administration of vasoactive drugs while the multimodal approach to prevention of such side effects can also reduce the incidence. Based on recent magnetic resonance imaging studies the volume of cerebrospinal fluid at the lumbosacral level is the main determinant of the effects produced by intrathecal injection of local anesthetic solutions. Unfortunately, it is not possible to estimate the volume of cerebrospinal fluid at the lumbosacral region in clinical practice, but it is clear that the total dose of local anesthetic injected into the subarachnoid space is the primary determinant of both therapeutic and unwanted effects of spinal anesthesia. There is overwhelming evidence of the potential risk for neurological dysfunction associated with spinal lidocaine. This evidence is even more relevant in outpatients, in whom lidocaine is primarily indicated. On the other hand, several studies have demonstrated the efficacy and safety of using small doses of long-acting agents, such as bupivacaine or ropivacaine, to produce a short spinal block. The addition of small doses of opioids further helps to minimize the dose of local anesthetic solution required, without affecting the recovery profile from spinal block. The extensive use of pencil-point designs for spinal needles, and the availability of needles of very small size have allowed a significant reduction in the incidence of postdural puncture headache.

SUMMARY

The changes in health care organization observed during the past few years have forced us to change the indications for and clinical uses of intrathecal anesthesia techniques in accordance with the changing needs of surgery. The development of new drugs and special techniques for spinal anesthesia will further improve the clinical use of this old but trusted technique.

Continuous spinal anesthesia for cesarean section in a parturient with severe preeclampsia

Epidural anesthesia is a widely accepted technique for cesarean section in the preeclamptic patient with normal coagulation. Regional anesthetic techniques avoid the hazards associated with tracheal intubation in the preeclamptic or eclamptic patient. To date, continuous spinal anesthesia in the preeclamptic parturient has not been described. We present a case in which continuous spinal anesthesia was administered for cesarean section in a morbidly obese parturient with severe preeclampsia. Continuous spinal anesthesia was successfully administered without significant hemodynamic consequences or maternal or fetal morbidity. This case suggests that continuous spinal anesthesia may be a viable alternative anesthetic technique for operative delivery in the preeclamptic parturient when epidural anesthesia cannot be established.

Regional anaesthesia with a subarachnoid microcatheter for caesarean section in a parturient with aortic stenosis

We present a woman in her first pregnancy, with known aortic stenosis prior to conception, who successfully underwent regional anaesthesia for an elective Caesarean section using a subarachnoid microcatheter. The anaesthetic management of patients with aortic stenosis requiring noncardiac surgery is a complex and contentious matter, particularly when the situation is compounded by the physiological changes accompanying pregnancy and delivery. This is the first reported use of a subarachnoid microcatheter in such a patient. The choice of technique is discussed and compared with other options for providing anaesthesia.