Low-dose bupivacaine spinal anaesthesia for percutaneous nephrolithotomy: the suitability and impact of adding intrathecal fentanyl.

BACKGROUND: Unilateral spinal anaesthesia has been used for lower limb surgery with a stable cardiovascular state and a short recovery unit stay. We sought to test the suitability of low-dose bupivacaine spinal anaesthesia for percutaneous nephrolithotomy, a procedure hitherto performed under general anaesthesia. Furthermore, we hypothesized that adding intrathecal fentanyl to bupivacaine may improve the quality of anaesthesia. METHODS: We randomly allocated, through computer-generated randomization, 108 patients subjected to percutaneous nephrolithotomy to receive either 7.5 mg of hyperbaric bupivacaine 5 mg/ml alone or with the addition of 10 microg of fentanyl. Drugs were given at the L(2)-L(3) interspace with the patient in the lateral decubitus position. The patients remained in this position for 10 min, after which the sensory and motor blocks were assessed. Intra-operative analgesic supplementation, when deemed necessary, was achieved with intravenous fentanyl boluses (25 microg). RESULTS: The sensory and motor blocks after intrathecal bupivacaine and bupivacaine-fentanyl were similar. Sensory block, in both groups, reached the fifth and eighth thoracic dermatomes on the operative and non-operative sides, respectively. Deep motor block occurred on the operative side in all patients and in nearly 50% of patients on the non-operative side. The patients in the bupivacaine-fentanyl group required less intra-operative and post-operative analgesics, and both patients and endoscopists were better satisfied. CONCLUSION: This study demonstrated, for the first time, that intrathecal low-dose bupivacaine and fentanyl offers a reliable neuraxial block for patients subjected to percutaneous nephrolithotomy, with stable haemodynamics, good post-operative analgesia and acceptable patient and endoscopist satisfaction.

Development of a difficulty score for spinal anaesthesia.

BACKGROUND: Multiple attempts at spinal puncture may be hazardous. Accurate preoperative prediction of difficulty adds to the delivery of high quality care. This clinical trial was designed to: (i). determine the predictive performance of difficulty variables; (ii). compare senior and junior anaesthetists; (iii). develop a score to predict difficulty during the performance of spinal anaesthesia. METHODS: A total of 300 patients subjected to urological procedures and scheduled for spinal anaesthesia were independently assessed and stratified according to the categories of the difficulty predictors of spinal anaesthesia into one of nine grades (0-8) and randomized according to the experience of the anaesthetist into two groups (group A, staff with more than 15 yrs' experience; group B, resident with more than 6 months but less than 1 yr in training). The number of attempts and levels, and success rate of the technique were the outcome variables. Data were analysed by multivariate analysis and receiver operating characteristic (ROC) curves. RESULTS: The bony landmarks of the back and the radiological characteristics of the lumbar vertebrae were two independent predictors of difficulty. Multivariate analysis indicated differences between junior and senior staff but ROC curves indicated no difference. Grade 4 was the difficulty score at or above which difficulty was expected whether or not radiological characteristics of the vertebrae were included. CONCLUSIONS: Spinal bony landmarks and radiological characteristics of the lumbar vertebrae are independent predictors of difficulty during spinal anaesthesia. There is no difference between senior and junior anaesthetists. Grade 4 is the difficulty score at or above which difficulty is expected.

Total intravenous anaesthesia with ketamine-midazolam versus halothane-nitrous oxide-oxygen anaesthesia for prolonged abdominal surgery.

BACKGROUND AND OBJECTIVE: Total intravenous anaesthesia (TIVA) with ketamine-midazolam (KM) can be used for prolonged abdominal surgery. We compared this technique with halothane-nitrous oxide-oxygen anaesthesia using haemodynamic and endocrine stress responses as primary outcomes and adequacy of operating conditions and recovery profile as secondary outcomes. METHODS: Fifty adult patients undergoing radical cystectomy and bladder substitution were randomly assigned to receive either TIVA with KM (n = 25) or halothane, nitrous oxide and oxygen anaesthesia (n = 25). Invasive haemodynamic and oxygenation variables were monitored along with plasma cortisol and growth hormone concentrations. Operative conditions and recovery profiles were registered. RESULTS: Cardiac index and vascular resistance remained stable during and after surgery. Cortisol concentrations doubled during surgery and remained elevated in the recovery period. Growth hormone increased after induction, peaked during surgery and decreased during recovery. Neither the haemodynamic variables nor the plasma hormone concentrations differed significantly between the two groups. Intestinal loops were collapsed in the KM groups providing better operative conditions and a reduced need for postoperative analgesics. CONCLUSIONS: The stress responses during KM anaesthesia for prolonged abdominal surgery were comparable to those during halothane-nitrous oxide-oxygen anaesthesia. However, KM anaesthesia provided better surgical conditions and better recovery.

Ketamine-midazolam total intravenous anaesthesia for prolonged abdominal surgery.

BACKGROUND AND AIM: Infusion of ketamine and midazolam can maintain prolonged anaesthesia, but delayed recovery is a limitation. We aimed to develop an approximation regimen for the infusion of ketamine and midazolam to obtain steady-state anaesthesia with acceptable recovery. METHODS: Thirty-one patients undergoing radical cystectomy were studied. The initial regimen was calculated from drug pharmacokinetic variables and tailored in a pilot study (15 patients) to develop the approximation regimen dosage. Anaesthesia was induced with midazolam (150 micrograms kg-1) and ketamine (2 mg kg-1). Tracheal intubation and ventilation with oxygen enriched air (FiO2 = 0.35) were facilitated by muscle relaxants. Anaesthesia was maintained by the approximation regimen doses. Routine monitoring was used for all patients, but pulmonary artery catheters were inserted in 11 patients, to obtain haemodynamic and oxygenation variables. RESULTS: Steady-state anaesthesia was obtained with minimal deviations in the regimen in some patients followed by reasonable recovery. CONCLUSION: It is concluded that infusion of ketamine and midazolam in the approximation regimen doses can be used to maintain anaesthesia for prolonged abdominal surgery.

Can we increase hepatic oxygen availability? The role of intentional hypercarbia.

Our hypothesis is that hypercarbia produces sympathetic stimulant effect and local vasodilatation. We studied the effect of intentional hypercarbia (IHC) on hepatic venous oxygen saturation. The hepatic vein (HV) was cannulated in 15 patients through either the right internal jugular vein or the femoral vein to measure HV oxygen saturation and calculate oxygen content. The inferior vena cava (IVC) was cannulated in 6 patients above and below drainage of the hepatic veins for oxygen saturation and content difference along the IVC. IHC was achieved in awake patients by breathing oxygen enriched air at a flow rate of 2L/min for 10 min, and during anesthesia by increasing anesthetic dead space and reducing tidal volume. IHC increased HV blood oxygen saturation, decreased the arterio-hepatic vein oxygen content difference and decreased oxygen saturation difference and oxygen content difference along IVC.

Acid-base equilibrium during capnoretroperitoneoscopic nephrectomy in patients with end-stage renal failure: a preliminary report.

We have studied the acid-base equilibrium in 12 patients with end-stage renal failure (ESRF) during capnoretroperitoneoscopic nephrectomy. Bupivacaine (12 mL, 0.375%) and morphine (2mg) were given in the lumbar epidural space, and fentanyl (0.5 microg kg(-1)) and midazolam (50 microg kg(-1)) were given intravenously. Anaesthesia was induced by thiopental, maintained with halothane carried by oxygen enriched air (inspired oxygen fraction = 0.35), and ventilation was achieved with a tidal volume of 10 mL kg(-1) at a rate of 12 min(-1). This procedure resulted in a mild degree of respiratory acidosis that was cleared within 60 min. We conclude that capnoretroperitoneoscopic nephrectomy can be performed in patients with end-stage renal failure with minimal transient respiratory acidosis that can be avoided by increased ventilation.

Perioperative renal protection in patients with obstructive jaundice using drug combinations.

BACKGROUND/AIMS: The effectiveness of dopamine alone or in combination with mannitol or furosemide in preventing postoperative renal dysfunction in patients with obstructive jaundice was assessed in this study. METHODOLOGY: Forty patients having obstructive jaundice were randomly allocated into 4 equal groups. Preoperative hydration was performed by infusing all patients 1L of 5% dextrose the night before surgery and another 1L in the morning before surgery. Intra- and postoperative maintenance of adequate intravascular volume was assured by fluid and blood replacement guided by the monitoring of central venous pressure urine output and blood pressure. The 1st group was kept as a control. The other 3 groups received dopamine 2.5 micrograms/kg/min for 2 postoperative days starting before surgery. The 2nd group was maintained on dopamine alone, while mannitol (0.25 g/kg), every 12 hours for 2 postoperative days, was added to the 3rd group. Similarly furosemide (1 mg/kg) every 12 hours for 2 postoperative days, was infused to the patients of the 4th group. Postoperative renal functions were assessed by 24-hour urine output, serum creatinine, creatinine clearance and urine to plasma osmolality ratio. RESULTS: All these tests did not show significant changes in the 1st, 2nd and 7th postoperative days. Only transient decreased creatinine clearance and elevated serum creatinine were observed in the patients of the 4th group in the 1st and 2nd postoperative days. This may be attributed to fluid imbalance induced by furosemide in these patients who were older than the other groups. CONCLUSIONS: The study showed that careful attention to perioperative hydration is the cornerstone in preserving adequate renal function following surgery in patients with obstructive jaundice. Administration of dopamine alone or in combination with mannitol or furosemide did not confer more renal protection.

Does spinal anesthesia affect cerebral oxygenation during transurethral prostatectomy?

BACKGROUND AND OBJECTIVES: Transurethral resection of the prostate (TURP) is associated with the unique complication of transurethral resection of prostate syndrome (TURS), which is attributed to the absorption of irrigating fluid. This study was initiated to investigate the effects of spinal anesthesia and TURP on cerebral oxygen balance. METHODS: Thirty patients scheduled for TURP were included. Jugular bulb oxygen saturation (SjbO2) was measured via retrograde cannulation of jugular venous bulb. Spinal anesthesia was initiated by 3 mL hyperbaric 0.5% bupivacaine injected at L3-L4 in the sitting position, producing a block to the T10 dermatome. Hemodynamic measurements and arterial and jugular bulb blood gasometry were performed before and after spinal anesthesia, throughout surgery, and during the postoperative period. RESULTS: A significant decrease of cerebral perfusion pressure after spinal anesthesia was accompanied by a significant decrease of SjbO2 below a preoperative value of 61% +/- 1. Eight patients developed yawning, irritability, restlessness, and nausea toward the end of surgery, and these were considered to be early signs of TURS. These patients demonstrated SjbO2 below 55% and 50% in 63% and 42% of respective data set points. CONCLUSION: The neurologic symptoms in patients undergoing TURP during spinal anesthesia might not only be caused by absorption of irrigating fluid but also by impairment of cerebral oxygenation.

Morphine-midazolam combination doses for presurgical analgesia in children.

We have examined the use of presurgical morphine-midazolam combination in 80 children aged 2-10 y undergoing repair of hypospadias. They were allocated randomly, in a double-blind study, to receive one of four morphine-midazolam combination doses (n = 20 each); (group I: 75 microg/kg each) [corrected] (group II: 75 microg/kg [corrected] morphine, 50 microg/kg [corrected] midazolam); (group III: 50 microg/kg [corrected] morphine, 75 microg/kg [corrected] midazolam); (group IV: 50 microg/kg [corrected] each). Drugs were given after induction of anesthesia and before the start of surgery. Observational scoring system, using crying, movement, agitation, posture and localization of pain as scoring criteria, was used to assess the children during their stay in the recovery room together with their sedative and/or analgesic requirement. Pre-surgical morphine-midazolam administration produced stable hemodynamic variables with satisfactory postoperative analgesia suggesting 75 microg/kg [corrected] dose of both morphine and midazolam as upper permissible dose, and 50 microg/kg [corrected] each as lower effective dose.

Plasma bupivacaine concentrations following epidural administration in kidney transplant recipients.

BACKGROUND AND OBJECTIVE: The typical hemodynamic and biochemical characteristics of kidney transplant recipients may influence the pharmacokinetic profile of bupivacaine following its epidural administration. The objective of this study was to test this hypothesis in kidney transplant recipients compared with kidney surgery patients. METHODS: In a prospective open comparative study, 10 kidney transplant recipients and 10 kidney surgery patients received bupivacaine by the lumbar epidural route during the course of their operations. Arterial blood sampling was carried out before administration of bupivacaine and at 2, 5, 10, 15, 20, 25, 30 minutes and subsequently at 1, 1.5, 2, 4, 8, and 24 hours, after its administration. RESULTS: The calculated pharmacokinetic variables did not show any significant difference between the two groups. CONCLUSIONS: Lumbar epidural administration of bupivacaine is not associated with higher plasma bupivacaine concentrations in kidney transplant recipients than in nonuremic patients undergoing kidney surgery.

Hemodynamic and oxygenation variables during radical cystectomy. Does the anesthetic technique really matter?

The effect of anesthetics on hemodynamic variables (HV) has been clarified, but ambiguity existed concerning their effect on oxygenation variables (OV). Radical cystectomy provided a clinical setting for studying the effect of anesthetics on perioperative HV and OV. Patients subjected to radical cystectomy (n = 33) were assigned through balanced randomization to receive one of four anesthetic modalities, namely; group I: inhalation anesthesia using N2O:O2, halothane, d-tubocurarine (n = 11); group II: inhalation anesthesia using N2O:O2, halothane, d-tubocurarine, and supplemented with epidural analgesia (EA) (n = 11); group III: total intravenous anesthesia (TIVA) using ketamine 10-30 ug.kg-1.min-1, propofol 2 mg.kg-1.h-1, d-tubocurarine, and supplemented with continuous EA (n = 6): and group IV:TIVA using ketamine 20-50 ug.kg-1.min-1, midazolam in increments of 1.5 to 5 mg, and supplemented with intermittent EA (n = 5). Monitoring entailed continuous ECG, pulse oximerty, invasive arterial pressure, and pulmonary artery catheter for HV (HR, MAP, PAP, PAOP, CO, SVR, and PVR) and OV. (PaO2, SaO2, PvO2, SvO2, a-vDO2, O2ext, Qs/Qt, DO2, and VO2). The heart rate was lower in TIVA while other HV did not show striking differences, Group I showed higher arterial oxygen tension than group II and IV. Mixed venous oxygen tension and saturation were higher in group I over group IV. Other OV did not show remarkable differences. In conclusion, HV and OV in 4 anesthetic modalities did not elicit striking differences.

Cardiac output measurement: lack of agreement between thermodilution and thoracic electric bioimpedance in two clinical settings.

STUDY OBJECTIVE: To determine the agreement between thermodilution (TD) and thoracic electric bioimpedance (TEB) techniques in cardiac output (CO) measurements in hyperdynamic kidney recipients and normodynamic patients subjected to radical cystectomy. The main objective was to determine the reliability of TEB in CO measurement. DESIGN: Open two-group study. SETTING: University hospital. PATIENTS: 19 kidney recipients and 5 radical cystectomy patients. INTERVENTIONS: Radial artery cannula and pulmonary artery floating catheter were inserted. The eight ECG spot electrodes of the TEB device were situated on the body surface. MEASUREMENTS AND MAIN RESULTS: Simultaneous CO measurements with TD and TEB were recorded at strategic points during the dynamic state of anesthesia and surgery. The mean difference (bias, TD-TEB) was higher in KRs (1.36 L/min) than radical cystectomy patients (-0.69 L/min). The corresponding 95% confidences of the bias were 1.10 to 1.54 L/min and -0.83 to -0.55 L/min. The precisions (SDs of bias) in kidney recipients and radical cystectomy patients were 1.08 L/min and 0.66 L/min, respectively. The limits of agreement were -0.97 to 3.51 L/min in kidney recipients and -1.99 to 0.61 L/min in radical cystectomy patients. The 95% confidences of the limits of agreement in kidney recipients were -1.09 to -0.49 for the lower limit and 3.21 to 3.81 for the upper limit. The corresponding values in radical cystectomy patients were -2.23 to -1.75 L/min and 0.37 to 0.85 L/min. CONCLUSIONS: These findings demonstrate lack of agreement between TEB and TD in CO measurements in a hyperdynamic and a normodynamic clinical setting. It is concluded that the TEB device is unreliable in CO measurement and cannot replace or be interchanged with TD.

Presurgical analgesia in children subjected to hypospadias repair.

We have examined the use of different pre-surgical analgesic techniques in 30 children aged 2-10 yr undergoing repair of hypospadias. They were allocated randomly, in a double-blind, placebo-controlled study, to receive one of three analgesic techniques (n = 10): lumbar extradural analgesia using 0.5% bupivacaine 1 mg kg-1 plus morphine 50 micrograms kg-1; morphine 100 micrograms kg-1 i.m.; or subpubic block using 0.5% bupivacaine 0.5 mg kg-1 for each side. Analgesics were given after induction of anaesthesia and before the start of surgery. Children given extradural analgesia had more stable haemodynamic variables and smaller catecholamine concentrations and needed less anaesthetic supplementation, with no analgesic requirement in the postoperative period. Nausea or vomiting were not reported in children given subpubic block.

Morphine elimination and hepatic blood flow--a study in patients with portal hypertension.

To investigate the influence of changes in portal venous blood flow on the clearance of morphine, the elimination of a single intravenous dose of morphine sulphate was studied in twelve patients with periportal fibrosis undergoing distal splenorenal shunt for portal hypertension. All patients had almost normal preoperative liver function. Six patients (Group A) received morphine after induction of anesthesia but before surgery; a further six patients (Group B) received morphine after completion of the splenorenal shunt and removal of all vascular clamps. Blood was sampled for 24 hours after morphine administration and analysed for plasma morphine concentration using high performance liquid chromatography. The maximum concentration of morphine was significantly greater in those patients in Group B who received morphine after the shunt (P < .002). Clearance of morphine during the operation was also significantly reduced in these patients compared with the initial clearance (before release of the clamps) in Group A (P < .004). As a consequence of these changes the AUC was greater in this group (P < 0.004). However, there were no differences with the elimination rates after surgery had finished. The results suggest that in individuals with normal liver function, the clearance of morphine is dependent on hepatic blood flow.

Does timing of hemodilution influence the stress response and overall outcome?

This study was designed to assess the stress response of acute hemodilution (AH) in patients subjected to radical cystectomy. Forty adult male patients were randomly allocated into a control group (n = 10) where homologous blood transfusion was used, a preinduction AH group (n = 20) where AH was performed before lumbar epidural block and induction of anesthesia, and into a postinduction group (n = 10) where AH was performed after induction of anesthesia. Monitored variables included hemodynamic, hematological and coagulation factors, liver function tests, and serum hormones. AH performed in awake or in anesthetized patients did not result in significant hemodynamic disruption, or result in detectable end-organ or stress-hormone changes when compared to control patient outcomes after radical cystectomy. Hemodilution can be performed by protocol for patients who are undergoing this procedure without major adverse effects.

Spinal versus epidural anesthesia during transurethral resection of the prostate.

The operative superiority of epidural anesthesia during transurethral resection of the prostate (TURP) stimulated this study. Twenty patients scheduled for TURP were randomly allocated to receive either spinal anesthesia (n = 10) with 8 ml bupivacaine 0.5%+ 5ml lignocaine 2%. During and after the operative procedure, PR, BP, ECG, and pulse oximetry were monitored, and blood Hb and Hct, plasma free Hb, and serum sodium and potassium levels were measured. Both techniques resulted in similar PR and BP changes. TURP with spinal anesthesia resulted in more prolonged period of hyponatremia and more increased duration of raised plasma free Hb.

Neuromuscular blocking activity of tubocurarine in patients with diabetes mellitus.

Previous clinical reports have suggested that deep tendon reflexes of diabetic patients are delayed and experimental studies have reported differential sensitivity of motor endplates to neuromuscular blocking drugs. These observations prompted us to study the neuromuscular effect of tubocurarine in 25 diabetic and 15 non-diabetic patients during urological surgery. Anaesthesia was induced with thiopentone followed by suxamethonium and maintained with nitrous oxide in oxygen and increments of butorphanol. Muscle relaxation was provided with tubocurarine in an initial dose of 0.25 mg kg-1 and increments of 20% of the initial dose. At the end of surgery, residual neuromuscular block was antagonized with increments of neostigmine 0.5 mg and atropine 0.2 mg. There was a delay in the onset of action of tubocurarine in diabetic patients. A no-response state was obtained in some patients, and its duration correlated with post-tetanic count (PTC) in diabetic patients, and with post-tetanic twitch height percent (PTTH%) in the control group. We concluded that, in diabetic patients, the onset of action of tubocurarine was delayed compared with control patients, and the reliable predictor of the duration of the no-response time was PTC in diabetic patients and PTTH% in non-diabetic subjects.

Renal effect of dopexamine hydrochloride in patients with chronic renal dysfunction.

Dopexamine hydrochloride, a dopamine analogue, has been reported, both experimentally and clinically, to increase renal blood flow (RBF) and improve renal function in normal kidneys. The availability of computer-enhanced radionuclide scintigraphy, which provides accurate non-invasive measurement of changes in RBF, enabled us to study the renographic effects of dopexamine hydrochloride in patients with chronic renal dysfunction (CRD). Ten patients suffering from CRD and ten normal kidney donors were the study population. Renography was performed, heart rate (HR) and blood pressure (BP) measured, and hematological and biochemical tests carried out before and after intravenous infusion of dopexamine 2 micrograms kg-1 min-1 for 60 min. The patient population displayed significant increases in total cortical and medullary RBF and renographic clearance rate (CR), while in kidney donors the RBF was increased in all kidney regions with no change in CR. HR increased in both groups, while BP showed no significant changes. The hematological and biochemical changes were transient and returned to preinfusion levels after 24 h. It is concluded that dopexamine hydrochloride 2 micrograms kg-1 min-1 increases RBF and CR in patients with CRD.

Immunological assays following exposure to halothane in clinical usage.

Venous blood samples were obtained from 30 patients undergoing surgical intervention, as well as 25 anaesthetists and operating-room personnel. Twenty non-exposed physicians served as a control group. Blood samples were subjected to total and differential leucocyte counts, T- and B-lymphocyte counts, serum immunoglobulin estimation, and in-vitro T-lymphocyte proliferative response to Con A-mitogen. In comparison with values from control subjects, halothane anaesthesia resulted in an increased number of T- and B-lymphocytes, whilst the serum immunoglobulins level and lymphoproliferative response were decreased. Three days after surgery, all the estimated parameters had returned to the pre-operative value. Chronic exposure to trace halothane concentrations resulted in decreased proliferative responses, lymphocytosis, and decreased immunoglobulins levels. It is concluded that halothane has different effects on the human immune system, depending on the particular conditions of the groups studied.