Intravenous fentanyl PCA during labour

Purpose

To evaluate the usefulness of intravenous patient-controlled analgesia (PCA) fentanyl for labour analgesia, its effectiveness for maternal pain and safety for the fetus and newborn.

Methods

Twenty primigravidas were randomised to receive intravenous PCA fentanyl or epidural analgesia for labour pain. Maternal pain, heart rate and arterial oxyhaemoglobin saturation (SpO₂) were monitored. Fetal and neonatal monitoring included cardiotocogram (CTG), APGAR, neurological scoring and static-charge-sensitive bed (SCSB) recording for 12 hr postnatally with ECG and SpO₂. Fentanyl concentrations and pH of umbilical artery and vein were analysed.

Results

Initially, epidural analgesia was more effective (P = 0.01 ), and three patients in the fentanyl group were given epidural due to unsatisfactory pain relief. Overall satisfaction for analgesia did not differ between the groups. Maternal side-effects were more frequent in the fentanyl group (dizziness and tiredness most often,P = 0.0001). Severe side-effects were not reported. In CTG there were no differences between groups. All the newborns were healthy, APGAR and pH were normal. Naloxone was not used. Neurological scoring was similar in both groups. In 12 hr monitoring heart rate, breathing frequency and movement time were similar in both groups, but SpO₂ was lower in the fentanyl group (P < 0.001 ). Umbilical cord fentanyl concentrations were low or beyond the detection limit.

Conclusion

Intravenous fentanyl can be used for labour analgesia with the doses reported here as an alternative to epidural analgesia. However, the fetus and neonate must be appropriately monitored. Naloxone and oxygen should be available if neonatal distress occurs.     

Comparative assessment of the anaesthetic and analgesic effects of intramuscular and epidural clonidine in humans

Purpose

The aim of the study was to assess and compare in analogous controlled experimental conditions, the anaesthetic sparing and analgesic effects of the same dose of clonidine administered by the intramuscular (im) and epidural (ep) routes.

Methods

We used a randomized, double blind and placebo controlled protocol. Sixty patients undergoing abdominal hysterectomy were distributed into three groups who, 30 min before surgical incision, received: 300 μg ep clonidine plus im saline; ep saline plus 300 μg im clonidine; or ep and im saline (ss). General anaesthesia was maintained with 60% N₂O in O₂, and isoflurane administered at concentrations to maintain mean arterial pressure (MAP) and heart rate (HR) within 20% of basal values. Isoflurane requirements (mass spectrometry), cardiovascular variables (MAP, HR), and plasma concentrations of glucose, cortisol and prolactin were evaluated at critical time points. In the recovery room (RR), sedation (Ramsay) and pain intensity (VAS) were estimated at the time of analgesia request (TAR).

Results

Intramuscular and ep clonidine decreased isoflurane requirements similarly by about 85% (P < 0.001). Patients in the ep group had lower MAP (P < 0.03) and HR (P < 0.001) than in the im group, but im and ep clonidine similarly blunted the plasma prolactin increase induced by intubation. In RR, ep but not im clonidine (P < 0.01) induced postoperative analgesia demonstrated by a prolonged TAR 80.8 ± 7.3 (ep) 35.9 ± 3.2 (im) and 44.5 ±5.1 (ss) min and a lower VAS (P < 0.05).

Conclusions

Epidural and intramuscular clonidine decreased isoflurane requirements similarly, but only the epidural route provided postoperative analgesia, suggesting a spinal site for the analgesic action.     

Continuous epidural infusion of ropivacaine for the prevention of postoperative pain after major orthopaedic surgery: a dose-finding study

Purpose

A dose-finding study to investigate the use of epidural infusions of ropivacaine for postoperative analgesia following orthopaedic surgery.

Methods

This was a randomized, double-blind study. Surgery was performed using a combination of a lumbar epidural block utilizing ropivacaine 0.5% and a standardized general anaesthetic. Postoperatively, an epidural infusion of the study solution (saline, ropivacaine 0.1%, 0.2% or 0.3%) was started at the rate of 10 ml · hr^?1 and continued for 21 hr after arrival in the PACU. Analgesia was supplemented with PCA morphine (dose = 1.0 mg, lock-out = 5 min).

Results

Forty-four patients completed the study. The ropivacaine 0.1%, 0.2%, 0.3% groups required less morphine over the 21 hr than the saline group (P < 0.01). The VAS pain scores were also lower in the three ropivacaine groups (P < 0.001). The ropivacaine groups maintained sensory anaesthesia to pinprick when compared with saline (P < 0.05). The motor block in the 0.3% group was significantly higher than the saline group at all times (P < 0.05), and higher than the 0.1% group at eight hours (P < 0.01), while the 0.2% group had higher Bromage scores than saline at 4 and 21 hr (P < 0.05).

Conclusions

The use of continuous epidural infusions of ropivacaine 0.1%, 0.2% and 0.3% at 10 ml · hr^?1 improved postoperative pain relief and decreased PCA morphine requirements in patients undergoing major orthopaedic surgery. The 0.1% and 0.2% concentrations produced similar sensory anaesthesia with less motor blockade than the 0.3% concentration.     

Haemodynamic consequences and uterine contractions following 0.5 or 1.0 litre crystalloid infusion before obstetric epidural analgesia

Purpose

The efficacy of infusion of 0.5 L and 1.0 L Ringer’s lactate (LR) to prevent hypotension during induction of obstetric analgesia was studied. The effect of the different fluid boluses on fetal heart rate (FHR) and frequency of uterine contractions were also determined.

Methods

Ninety-two ASA 1–2 parturients were randomized to receive 0.5 L (Group 1) and 1.0 L (Group 2) LR immediately before incremental epidural injections with lidocaine to achieve T₁₀ sensory block. Systolic blood pressure (SBP) was measured with an automated BP cuff every two minutes for 30 min after infusion of fluid bolus. Fetal heart rate monitoring and tocometry were used continuously. The number of uterine contractions were recorded 30 min before and 60 min after iv bolus.

Results

The SBP decreased in both groups, but there was no difference between groups in mean SBP or maternal heart rate. The incidence of hypotension (SBP < 90 mmHg or decrease of 20%) was 4% in both groups. The FHR record of a patient in Group 1 showed a single late deceleration, and a decrease in beat-to-beat variability occured in one patient in Group 2. A decrease in the frequency of uterine contractions of two or more contractions per 30 min was noted more frequently in Group 2 (P < 0.05). The duration of iv bolus was longer in Group 2 than Group 1 (18.8 ± 4.3 min vs 12.3 ± 4.5 min, P < 0.01).

Conclusion

Administration of 1.0 L LR iv does not provide added protection against maternal hypotension, and is associated with delay in providing pain relief and a risk of decreasing uterine contraction frequency.     

Enhanced pain management for post-gastrectomy patients with combined epidural morphine and fentanyl

Purpose

To determine whether clinical advantages could be demonstrated by epidural fentanyl given in addition to epidural morphine for postgastrectomy analgesia.

Methods

One-hundred and twenty two patients undergoing elective gastrectomy were prospectively studied in a randomised, double-blind fashion. All patients received epidural lidocaine 1.5% with epinephrine (1:200,000) followed by light general anaesthesia for surgical anaesthesia. They were assigned to four groups according to the combinations of each epidural opioid: 2 mg morphine alone, 2 mg morphine + 100μg fentanyl, 4 mg morphine alone, and 4 mg morphine + 100 μg fentanyl. Morphine and fentanyl were given epidurally approximately 60 and 15 min, respectively, before the completion of surgery.

Results

Addition of epidural fentanyl to both doses of morphine not only decreased intensity of pain associated with coughing during the early postoperative period, but also prolonged the time until the first analgesic request at each morphine dose studied. Of the combination doses, 4 mg morphine + 100 μg fentanyl provided the longest time to the first request for analgesic, and was associated with least amount of postoperative analgesic supplement and best patient satisfaction without increasing incidence of side effects.

Conclusion

The addition of 100 μg fentanyl to 2 mg or 4 mg epidural morphine provides clinical advantages over morphine alone for post-gastrectomy analgesia.     

Epidural ketamine reduces post-operative epidural PCA consumption of fentanyl/bupivacaine

Purpose

To study the analgesic effect of epidural ketamine on postoperative pan and epidural PCA consumption after total abdominal hysterectomy.

Methods

Sixty-one ASA I–II patients, 34–60 yr were randomly assigned into three groups. Epidural catheters were inserted before induction of anaesthesia. Patients in group I and II received 30 mg ketamine epidurally before induction of anaesthesia or 20 min after skin incision: group III received placebo, Postoperatively, on first analgesia request, sedation score, Visual Analogue Scale (VAS), Prince Henry Score (PHS) and Bromage motor weakness score were taken and followed by an epidural bolus of 9 ml bupivacaine 0.25% + 50 μg fentanyl. Analgesia was maintained by PCA with a mixture of bupivacaine 0.1% + fentanyl 0.001% epidurally. Measurements were repeated at 1, 2, 4, 8, 12 and 24 hr.

Results

First analgesia request was 17 ±6.8 min in the control group compared with 31.4 ±23.8 and 44 ±23.1 min for groups I and II respectively. The differences between group III and group I (P < 0.05) and between group III and group II (P < 0,01) were statistically significant. Twenty four hour PCA consumption was 101.2 ±47.2, 87 ±27 and 162 ±38 ml for groups I, II and III respectively. The differences between group III and group I and that between group III and group II were statistically significant (P < 0.001 ).

Conclusion

Epidural ketamine 30 mg reduces post hysterectomy pain as evidenced by prolongation of time to first analgesia request and reduction in postoperative epidural PCA consumption. This effect is manifest whether ketamine is given before induction or 20 min after skin incision.     

Comparison between epidural infusion of fentanyl/bupivacaine and morphine/bupivacaine after orthopaedic surgery

Purpose

To compare epidural infusions of bupivacaine-fentanyl and bupivacaine-morphine mixtures for postoperative pain relief after total hip replacement.

Methods

In a prospective, randomized, double-blind study, 30 ASA physical status I–II patients undergoing total hip replacement were studied. Anaesthesia was provided by combined general/epidural anaesthesia without epidural opioids. Postoperative epidural analgesia was by continuous infusion of bupivacaine 0.125% (4 ml·hr^?1) with either 0.05 mg·ml^?1 morphine (morphine, n = 15) or 0.005 mg·ml^?1 fentanyl (fentanyl, n = 15). Visual analogue pain scale (VAS), sedation (fourpoint scale), respiratory rate, pulse oximetry, rescue analgesics and supplemental oxygen were recorded by a blind observer at 1,3, 6, 9, 12 and 24 hr after surgery.

Results

No differences in pain relief, sedation, or non-respiratory side effects were observed between the two groups. Rescue analgesics were required in three patients in the fentanyl group (20%) and in two receiving morphine (13.3%) (P:NS). Two patients in the fentanyl group and three in the morphine group required oxygen due to SpO₂ < 90% (P:NS). Both opioid/bupivacaine mixtures decreased haemoglobin oxygen saturation compared with preoperative values. The mean ± SD SpO₂ values measured at 3,6, 12 and 24 hr were 94.4 ± 1, 92.6 ± 0.9, 92 ± 0.8, and 92.8 ± 1 in the morphine group, 95.3 ± 0.5, 95 ± 0.5, 94.6 ± 1.2, and 95.6 ± 1 in the fentanyl group (P < 0.05).

Conclusion

Continuous epidural infusion of bupivacaine-morphine or bupivacaine-fentanyl mixtures provided similar pain relief. Patients receiving morphine showed a more marked decrease in SpO₂ than those receiving fentanyl. However, the average SpO₂ remained > 90% in both groups.     

Alkalinization improves the quality of lidocaine-fentanyl epidural anaesthesia for Caesarean section

This double-blind randomized study of 116 healthy women was undertaken to evaluate whether alkalinization potentiated the analgesic effects of epidural fentanyl-lidocaine for elective Caesarean section. After a test-dose of 3 ml, lidocaine 2% with adrenaline 1:200,000, all patients received 100 μg, fentanyl in 5 ml saline and they were then divided into two groups, to receive incremental doses of 5 ml lidocaine 2% with adrenaline 1:200,000 with or without 0.1 mEq · ml^?1 sodium bicarbonate, to obtain anaesthesia to T₄. The addition of bicarbonate to lidocaine resulted in a mean (SD)pH increase from 6.58 (0.01) to 7.14 (0.02) and in a mean PCO₂ increase from 3.8 (0.8) to 345.1 (5.9) mmHg. Onset of sensory analgesia to the S₁ segment as well as the interval between the block and the delivery of the baby were shorter in the bicarbonate group (respectively 15.4 (6.9) vs 18.9 (4.8) min and 28.9 (9.5) versus 33.9 (11.8) min; P < 0.01 and 0.05). No differences were noted in the onset to T₄ or in the degree of motor block. The percentage of patients experiencing pain during surgery and requiring intravenous analgesics was higher in the group which did not receive bicarbonate (3% vs 16%; P < 0.05). There were no differences in intraoperative maternal side-effects, neonatal outcome or in maternal venous and umbilical venous and arterial lidocaine concentrations between the groups. The concentrations of fentanyl in maternal plasma, umbilical artery, and the umbilical artery to maternal vein ratio were greater in the alkalinized group (P < 0.001). In conclusion, alkalinization improves the quality and reliability of epidural anaesthesia provided with fentanyl and lidocaine for Caesarean section in healthy mothers.     

Recovery of post-tetanic and train-of-four responses at the first dorsal interosseous and adductor pollicis muscles in patients receiving vecuronium

Purpose

To compare recovery of accelographical responses to post-tetanic twitch (PTT) and train-of-four (TOF) stimuli obtained at the first dorsal interosseous muscle (DI) with those at the adductor pollicis muscle (AP) after administration of vecuronium 70 μg · kg^?1.

Methods

Sixty adult patients were randomly assigned to one of four groups: PTT-DI (n = 15), PTT-AP (n = 15), TOF-DI (n = 15), or TOF-AP (n = 15) group. In PTT-DI and PTT-AP groups, responses to PTT were measured accelographically at the DI and at the AP, respectively. In TOF-DI and TOF-AP groups, responses to TOF were measured at the DI and at the AP, respectively.

Results

The T₁/T₀ (T₀ = control) was greater in the TOF-DI than in TOF-AP group throughout recovery (P < 0.05), and the T₄/T₁ was greater in the TOF-DI than in TOF-AP group during the 30–40 min after vecuronium injection (P < 0.05). Time to the return of the first response to PTT (post-tetanic count₁, PTC₁) was less in the PTT-DI than in the PTT-AP group (17.7 ± 4.2 vs 21.7 ± 5.6 min, mean ± SD, P = 0.0341). The post-tetanic count PTC (number of single twitch stimuli in response to PTT) was greater in the PTT-DI than in the PTT-AP group during the 10–30 min after vecuronium (P < 0.05). Time to the return of T₁ was less in the TOF-DI than in the TOF-AP group (23.1 ± 6.0 vs 27.6 ± 4.9 min, P = 0.0334).

Conclusion

Recovery of responses to PTT and TOF stimuli occurred earlier at the DI than at the AP.     

Epidural and intravenous bolus morphine for postoperative analgesia in infants

Purpose

To compare two doses of bolus epidural morphine with bolus iv morphine for postoperative pain after abdominal or genitourinary surgery in infants.

Methods

Eighteen infants were randomly assigned to bolus epidural morphine (0.025 mg · kg^?1 or 0.050 mg · kg^?1) or bolus iv morphine (0.050–0.150 mg · kg^?1). Postoperative pain was assessed and analgesia provided, using a modified infant pain scale. Monitoring included continuous ECG, pulse oximetry, impedance and nasal thermistor pneumography. The CO₂ response curves and serum morphine concentrations were measured postoperatively.

Results

Postoperative analgesia was provided within five minutes by all treatment methods. Epidural groups required fewer morphine doses (3.8 ± 0.8 for low dose [LE], 3.5 ± 0.8 for high dose epidural [HE] vs. 6.7 ± 1.6 for iv, P < 0.05) and less total morphine (0.11 ± 0.04 mg · kg^?1 for LE, 0.16 ± 0.04 for HE vs 0.67 ± 0.34 for iv, P < 0.05) on POD1 Dose changes were necessary in all groups for satisfactory pain scores. Pruritus, apnoea, and haemoglobin desaturation occurred in all groups. CO₂ response curve slopes, similar preoperatively (range 36–41 ml · min^?1 · mmHg ETco ₂ ^?1 · kg^?1) were generally depressed (range, 16–27 ml · min^?1 · mmHg ETco ₂ ^?1 · kg^?1) on POD1. Serum morphine concentrations, negligible in LE (<2 ng · ml^?1), were similar in the HE and iv groups (peak 8.5 ± 12.5 and 8.6 ± 2.4 ng · ml^?1, respectively).

Conclusion

Epidural and iv morphine provide infants effective postoperative analgesia, although side effects are common. Epidural morphine gives satisfactory analgesia with fewer doses (less total morphine); epidural morphine 0.025 mg · kg^?1 is appropriate initially. Infants receiving epidural or iv morphine analgesia postoperatively need close observation in hospital with continuous pulse oximetry.     

Epidural administered buprenorphine in the perioperative period

Purpose

To study the effect of epidural buprenorphine on minimum alveolar concentration (MAC) of volatile anaesthetics, duration of analgesia and respiratory function in the perioperative period.

Methods

One hundred and twenty patients, ASA I–II undergoing gynaecological surgery were randomly divided into three studies. The forty patients in each study were randomly divided into four groups depending on the dosage; Group I (control), Group II (80 μg · kg^?1 morphine), Group III (4 μg · kg^?1 buprenorphine), Group IV (8 μg · kg^?1 buprenorphine). The MAC of halothane was measured following epidural administration of the agents in each group. The duration of analgesia was assessed by the first request for pentazocine. Postoperative analgesic effects were assessed by the total dosage of pentazocine required for the 48 hr after surgery. Respiratory rate (RR), minute volume (MV), and PaCO₂ were measured during surgery and the postoperative period. The MAC of halothane was reduced in Group IV (P < 0.01). The duration of analgesia was 10.0 ± 5.1 hr (Mean ± SE) in Group 1, 37.7 ± 4.7 hr in Group II, 27.1 ± 7.1 hr in Group III, and 44.4 ± 4.1 hr in Group IV. Total dosage of pentazocine was lower in Group IV (P < 0.05) than in the other groups. The decrease of RR, MV and the increase of PaCO₂ were observed within 60 min in Group III and IV dose dependently.

Conclusion

Epidural buprenorphine administered in a dose of 4 or 8 μg · kg^?1 provides postoperative analgesia that is no less effective than that of morphine.     

A comparison of lumbar epidural and intravenous fentanyl infusions for post-thoracotomy analgesia

This double-blind randomised study compared the analgesic efficacy, respiratory effects, side effects, and pharmacokinetic disposition of 24 hr lumbar epidural and intravenous infusions of the same dosage regimen of fentanyl (1.5 μg · kg^?1 bolus then 1 μg · kg^?1 · hr^?1 infusion) in 50 patients after thoracotomy. Patients received either epidural fentanyl and intravenous normal saline, or epidural normal saline and intravenous fentanyl, for postoperative analgesia, after a standard low-dose alfentanil and isoflurane general anaesthetic. Visual analogue pain scores were lower in the epidural group (P < 0.05) only at two hours postoperatively, and there was no difference in the amount of supplementary morphine self-administered by patient-controlled analgesic pump. A mainly spinal analgesic effect probably occurred in the first few hours since fentanyl was not detectable in the plasma of patients in the epidural group until two hours after bolus injection; its concentration was less at that time than after intravenous injection (P < 0.05). Thereafter there was no difference in the plasma concentration profiles between the two groups. Seven patients in the epidural group and ten patients in the intravenous group received naloxone for PaCO₂ > 50 mmHg, and one patient in the intravenous group had the infusions stopped because of PaCO₂ elevation and somnolence. In patients who did not receive naloxone, the epidural route produced better analgesia throughout the study period (P < 0.01). Indices of respiratory centre function (apnoeas > 15 sec, slow respiratory rate < 10 min^?1, oxyhaemoglobin desaturation < 90% and PaCO₂) spirometric measures of pulmonary function, haemodynamic variables, morbidity, and other side effects, were similar in both groups, irrespective of naloxone therapy. Patients who had no respiratory depression and did not require naloxone had better analgesia with epidural fentanyl. However, this advantage did not result in better pulmonary function.     

Spread of epidural analgesia following a constant pressure injection

(1) The spread of epidural analgesia following injection of 15ml of 2% mepivacaine was 17.3 ± 0.6, 14.3 ± 0.4, and 13.3 ± 0.7 spinal segments in cervical, thoracic, and lumbar epidural analgesia, respectively. The patients age showed significant correlation with the spread of epidural analgesia in cervical (r = 0.5776, p < 0.001), thoracic (r = 0.3758, p < 0.01), and lumbar area (r = 0.8195, p < 0.001). The spread of cervical epidural analgesia was more caudad than cephalad (p < 0.05), but in lumbar epidural analgesia it was more cephalad than caudad (p < 0.05). There was no difference between the cephalad and caudad spread in thoracic epidural analgesia.(2) The epidural pressure immediately after injection of 15ml of 2% mepivacaine into the lumbar epidural space at a constant pressure (80mmHg) correlated to the patients age (r = –0.5714, p < 0.001) and the spread of analgesia (r = –0.3904, p < 0.05). The lower epidural pressure associated with higher age, the wider spread of analgesia. There was no significant correlation between the residual pressure at 60 seconds and the age or the spread of analgesia.(Hirabayashi Y et al.: Spread of epidural analgesia following a constant pressure injection: an investigation of relationships between locus of injection, epidural pressure and spread of analgesia. J Anesth 1: 44–50, 1987)     

Risk factors of inadequate pain relief during epidural analgesia for labour and delivery

Purpose

To determine the causes of failure of epidural analgesia during labour and delivery.

Methods

During six months, pregnant patients receiving epidural analgesia and delivering vaginally were studied prospectively. Bupivacaine 0.125% was used for the initial bolus dose and subsequent continuous infusion. Top-ups of the same solution were used for inadequate pain relief assessed using a visual analogue pain score (VAPS) and/or by clinical examination. Inadequate pain relief was defined as the need for ≥ 2 top-ups in addition to epidural infusion and failure during delivery as VAPS ≥ 30 mm during the expulsion phase.

Results

1009 patients delivered during this period, 596 had epidural analgesia for vaginal delivery of a live infant and data were complete in 456. Inadequate pain relief during labour and during delivery were found in 5.3% and 19.7% of patients. Risk factors of inadequate pain relief included: inadequate analgesic efficacy of the first dose (Odds ratio: 3.5, P = 0.001) and posterior presentation (Odds ratio: 5.6, P = 0.001). Radicular pain during epidural placement was associated with failure during labour (Odds ratio: 3.9, P = 0.05). Duration of epidural analgesia > six hours (Odds ratio: 9.1, P = 0.001) was a risk factor for insufficient pain relief during labour whereas duration of epidural analgesia < one hour was associated with pain during delivery (Odds ratio: 18.3, P = 0.001).

Conclusion

Several obstetrical and epidural-related factors increase the risk of inadequate epidural analgesia. For some, simple changes of practice pattern may lead to improved pain relief.     

Early neuromuscular recovery characteristics following administration of mivacurium plus vecuronium

Purpose

This study was designed to describe the early recovery characteristics, as well as the speed of onset of neuromuscular block, after a combination of mivacurium and vecuronium.

Methods

In this controlled, randomized study, 30 consenting ASA I–III patients were assigned to three treatment groups. The “2M2V” group received twice the dose necessary to cause 95% depression of the evoked twitch response (2 × ED₉₅) of mivacurium (0.15 mg · kg^?1) plus 2 × ED₉₅ of vecuronium (0.1 mg · kg^?1); the “2V” group received 2 × ED₉₅ of vecuronium; and the “4V” group received 4 × ED₉₅ of vecuronium. Evoked neuromuscular responses of the adductor pollicis were assessed with an adductor pollicis force transducer. The time until maximum block and times to 10% and 25% recovery (T₁₀ and T₂₅) in each group were expressed as mean ± standard deviation and compared using ANOVA.

Results

Onset of block in the 2M2V group was 27% faster than in the 2V group (2.0 ± 0.6 vs. 2.7 ± 0.8 min respectively, P < 0.05) and was similar to the 4V group (1.95 ± 0.3 min, P = NS). The times until 10% recovery were similar in the 2M2V and 4V groups (59.9 ± 12 vs 68.2 ± 25 min, P = NS) and were slower than in the 2V group (37.2 ± 9 min, P < 0.05). Between T₁₀ and T₂₅, recovery after 2M2V resembled that after 2V (6.7 ± 3 vs 5.7 ± 1 min, P = NS) and was faster than after 4V (10.9 ± 7 min, P<0.05).

Conclusions

When 2 × ED₉₅ of mivacurium is added to 2 × ED₉₅ of an intermediate or long-acting relaxant, recovery after T₁₀ will proceed as if one had administered the longeracting agent alone.     

A Nationwide Analysis of the Use and Outcomes of Epidural Analgesia in Open Colorectal Surgery

Introduction

Epidural analgesia has demonstrated superiority over conventional analgesia in controlling pain following open colorectal resections. Controversy exists regarding cost-effectiveness and postoperative outcomes.

Methods

The Nationwide Inpatient Sample (2002–2010) was retrospectively reviewed for elective open colorectal surgeries performed for benign and malignant conditions with or without the use of epidural analgesia. Multivariate regression analysis was used to compare outcomes between epidural and conventional analgesia.

Results

A total 888,135 patients underwent open colorectal resections. Epidural analgesia was only used in 39,345 (4.4 %) cases. Epidurals were more likely to be used in teaching hospitals and rectal cancer cases. On multivariate analysis, in colonic cases, epidural analgesia lowered hospital charges by US$4,450 (p?<?0.001) but was associated with longer length of stay by 0.16 day (p?<?0.05) and a higher incidence of ileus (OR?=?1.17; p?<?0.01). In rectal cases, epidural analgesia was again associated with lower hospital charges by US$4,340 (p?<?0.001) but had no effect on ileus and length of stay. The remaining outcomes such as mortality, respiratory failure, pneumonia, anastomotic leak, urinary tract infection, and retention were unaffected by the use of epidurals.

Conclusion

Epidural analgesia in open colorectal surgery is safe but does not add major clinical benefits over conventional analgesia. It appears however to lower hospital charges.     

Optimum time for neostigmine reversal of atracurium-induced neuromuscular blockade

Purpose

The aim of the study was to determine the optimum time for administration of neostigmine during recovery from atracurium-induced neuromuscular blockade.

Methods

The study comprised 103 patients anaesthetised with midazolam, fentanyl, thiopentone, halothane, and nitrous oxide. Relaxation was induced with atracurium 0.5 mg·kg^?1 and maintained with supplements of 0.15 mg·kg^?1. The ulnar nerve was stimulated with train-of-four (TOF) and double burst stimulation (DBS). Evoked MMG responses were recorded. Patients were randomized to spontaneous recovery (n = 20) or to assisted recovery by neostigmine (0.07 mg ·kg^?1) at varying intervals (6–50 min) from the last atracurium dose (n = 83).

Results

The reversal time (time from administration of neostigmine to TOF ratio 0.7) was always < 13 min, when T₁ (first twitch in TOF) was detectable or when D₁ (first twitch in DBS) was > 5%. Total assisted recovery time (time from last supplemental atracurium dose to TOF ratio 0.7) increased with increasing T₁ and D₁ twitch heights (P < 0.05). The curve fitted to the scattergram with total assisted recovery time vs time from last atracurium supplement to neostigmine administration decreased to reach a minimum after which it increased to approach the line of identity. The minimum of the curve (total assisted recovery time 30.7 min) was reached when neostigmine was given 18.6 min after last atracurium supplement. At this time the T₁ and D₁ twitch height averaged 4 and 8% respectively. If prolongation of the minimum total recovery time of 2.5% is accepted, neostigmine can be given at T₁ and D₁ twitch height values of 0 to 8% and 4 to 15%, respectively.

Conclusion

The optimum time for neostigmine administration, taking both the reversal time and total recovery time into consideration, is when 0 < T₁ < 8% or when 5 < D₁ < 15%. Giving neostigmine at more profound degrees of blockade prolongs reversal time, while giving neostigmine later in the recovery phase prolongs total recovery time.     

Periarticular infiltration for pain relief after total hip arthroplasty: a comparison with epidural and PCA analgesia

Purpose

Epidural and intravenous patient-controlled analgesia (PCA) are established methods for pain relief after total hip arthroplasty (THA). Periarticular infiltration is an alternative method that is gaining ground due to its simplicity and safety. Our study aims to assess the efficacy of periarticular infiltration in pain relief after THA.

Methods

Sixty-three patients undergoing THA under spinal anaesthesia were randomly assigned to receive postoperative analgesia with continuous epidural infusion with ropivacaine (epidural group), intraoperative periarticular infiltration with ropivacaine, clonidine, morphine, epinephrine and corticosteroids (infiltration group) or PCA with morphine (PCA group). PCA morphine provided rescue analgesia in all groups. We recorded morphine consumption, visual analog scale (VAS) scores at rest and movement, blood loss from wound drainage, mean arterial pressure (MAP) and adverse effects at 1, 6, 12, 24 h postoperatively.

Results

Morphine consumption at all time points, VAS scores at rest, 6, 12 and 24 h and at movement, 6 and 12 h postoperatively were lower in infiltration group compared to PCA group (p < 0.05), but did not differ between infiltration and epidural group. There was no difference in adverse events in all groups. At 24 h, MAP was higher in the PCA group (p < 0.05) and blood loss was lower in the infiltration group (p < 0.05).

Conclusions

In our study periarticular infiltration was clearly superior to PCA with morphine after THA, providing better pain relief and lower opioid consumption postoperatively. Infiltration seems to be equally effective to epidural analgesia without having the potential side effects of the latter.     

The effects of secondhand smoke on postoperative pain and fentanyl consumption

Background

Although the need for increased postoperative analgesia in smokers has been described, the effect of secondhand smoke on postoperative analgesia requirements has not been studied. We examined the effects of secondhand smoke on fentanyl consumption and postoperative pain.

Methods

In this study, 101 patients (American Society of Anesthesiology physical status I and II) who underwent abdominal hysterectomy were divided into 3 groups according to history of exposure to cigarette smoke as per medical records which was retrospectively confirmed by measurement of serum cotinine: smokers (n = 28), nonsmokers (n = 31), and secondhand smokers (n = 32). All patients received propofol–remifentanil total intravenous anesthesia and used fentanyl patient controlled analgesia for postoperative pain. The fentanyl consumption visual analogue scale-pain intensity (VAS-PI) score and side effects were recorded in the postanesthesia care unit (PACU) and at 2, 4, 6, and 24 h after surgery.

Results

Fentanyl consumption at all the evaluation time points was significantly higher in secondhand smokers than in nonsmokers (P < 0.05). However, fentanyl consumption in secondhand smokers was lower than that in smokers in the PACU and at 24 h (P < 0.05). VAS-PI scores during movement and at rest in the PACU and at 4, 6, and 24 h after surgery were higher in secondhand smokers than in nonsmokers (P < 0.05). There were no statistically significant differences between the groups with regard to side effects such as nausea, vomiting, and dizziness (P > 0.05).

Conclusion

Secondhand smoking was associated with increased postoperative fentanyl consumption, and increased VAS-PI scores. These findings may be beneficial for managing postoperative pain in secondhand smokers.     

Pharmacokinetics of propofol in patients undergoing total hip replacement

Objective

The aim of the study was to investigate the effects of acute hypervolemic hemodilution (HHD) on the pharmacokinetics of propofol in patients undergoing total hip replacement.

Methods

A total of 16 patients undergoing elective surgery for total hip replacement under general anesthesia in combination with epidural analgesia were randomly assigned to 2 groups: the control group (n?=?8) or the HHD group (n?=?8). All patients in both groups received lactated Ringer??s solution before induction of general anesthesia. In the control group the conventional fluid replacement protocol was used. In the HHD group 4% succinylated gelatin was infused at the rate of 20?ml?kg^?1BW?h^?1 with a targeted hematocrit of 30. Anesthesia was induced with midazolam 0.04?mg?kg^?1, fentanyl 4???g?kg^?1 and propofol 1.5?mg?kg^?1. Tracheal intubation was facilitated by infusion of succinylcholine 2?mg?kg^?1. Anesthesia was maintained with isoflurane, fentanyl, vecuronium and epidural analgesia. Electrocardiogram (ECG), blood pressure (BP), blood oxygen saturation (SpO₂), partial pressure of end-tidal carbon dioxide (P_ETCO₂) and central venous pressure (CVP) were monitored continuously. Blood samples were taken at 1, 2, 4, 6, 10, 15, 30, 45, 60, 75, 90, 120, 150, 180, 240, 300 and 360?min after propofol administration to determine plasma concentrations of propofol by high performance liquid chromatography (HPLC).

Results

Plasma propofol concentrations were significantly lower in the HHD group than in the control group at 1, 2, 4, 6 and 10?min after propofol administration (p??>?0.05). In the HHD group the volume of distribution of the central compartment (V_C) increased significantly, elimination half-life (T_{1/2 ??}) was significantly prolonged, the elimination rate constant (K₁₀) and the whole-body clearance (CL) were significantly decreased compared with the control group (p?1/2 _??), half-life of the slower distribution phase (T_{1/2 ??}), K₁₂, K₂₁, K₁₃, K₃₁ and the area under the curve (AUC) (p?>?0.05). The pharmacokinetic profile of propofol is best described by a three-compartment model in both groups using minimal Akaike information criteria (AIC).

Conclusion

Acute HHD increases V_C, prolongs the T_{1/2 ??}, and decreases K₁₀ and CL, which suggests that care must be taken when propofol is used in patients undergoing HHD. The induction dose should be increased, but the maintenance dose should be decreased. The time to emergency from anesthesia will likely be prolonged, especially in patients receiving prolonged continuous infusions.