Anaesthetic management of a parturient with pulmonary stenosis and aortic incompetence for Caesarean section.

Anaesthetic management of Caesarean section in a parturient with severe pulmonary stenosis and aortic regurgitation is described. The valvular sequelae resulted from previous unsuccessful surgical correction (Ross procedure) of congenital aortic stenosis. This case demonstrates the importance of multi-disciplinary assessment and careful anaesthetic planning, to avoid deterioration in perioperative cardiac performance in parturients with complex valvular disease.

Effect of preemptive multimodal analgesia for arthroscopic knee ligament repair.

BACKGROUND AND OBJECTIVES: Administration of analgesic medication before surgery, rather than at the completion of the procedure, may reduce postoperative pain. Similarly, administration of multiple analgesics, with different mechanisms of action, may provide improved postoperative pain control and functional recovery. The purpose of our study was to compare pain scores and intravenous opioid consumption after outpatient anterior cruciate ligament (ACL) reconstruction in patients who received a multimodal drug combination (intravenous [IV] ketorolac, intra-articular morphine/ropivacaine/epinephrine, and femoral nerve block with ropivacaine) either before surgery or immediately at the completion of the surgical procedure. METHODS: Forty patients presenting for same-day arthroscopic ACL repair using a semitendinosis tendon graft were included in this study. The patients were randomized to receive the following drugs either 15 minutes before skin incision or immediately after skin closure: (1) Ketorolac 30 mg IV. (2) Intra-articular injection of 20 mL ropivacaine 0.25% + morphine 2 mg and epinephrine 1:200,000. (3) Femoral nerve block with 20 mL ropivacaine 0.25%. Verbal pain scores were obtained in the postanesthesia care unit (PACU) and on postoperative days 1, 3, and 7. IV patient controlled analgesia (PCA) morphine consumption in the PACU was also recorded. RESULTS: Verbal pain rating scores were lower in group I (preemptive) for 2.0 hours after arrival in the PACU. There was no difference between groups in pain scores on postoperative days 1, 3, and 7. Mean IV PCA morphine consumption in the PACU was lower in group I (6.4 mg) versus group II (12.3 mg), P <.05. CONCLUSION: Preemptive, multimodal administration of our 3-component analgesic drug combination resulted in lower pain scores during the initial stay in the PACU unit and lower consumption of IV PCA morphine in the PACU. However, pain scores were similar in both groups on postoperative days 1, 3, and 7; thus, there was no measurable long-term advantage associated with preemptive multimodal drug administration.

Visualization of a looped and knotted epidural catheter with a guidewire.

PURPOSE: To describe the management of a looped and knotted epidural catheter after analgesia for labour and delivery. CLINICAL FEATURES: Obstetrical epidural pain relief was provided for a 37-yr old woman in early labour. A 20-gauge Portex catheter was inserted at the L2-L3 interspace. Six centimetres of catheter was left in the epidural space. After vaginal delivery the catheter could not be removed. The catheter was left in situ for 24 hr. Repeated attempts at removal were again unsuccessful. The epidural catheter was not visible with fluoroscopy and it was impossible to inject radiopaque dye into the catheter. However, we successfully advanced a 0.016 inch guidewire through the epidural catheter and radiologically demonstrated a knot and part of a loop. The catheter was removed by an orthopedic surgeon using blunt dissection under local anesthetic from the soft tissue just lateral to the interspinous ligament. CONCLUSIONS: A knot can be a rare cause of a trapped epidural catheter. A suggested approach to the trapped lumbar epidural catheter: 1) Gentle traction on the catheter with the patient in various positions and in various degrees of lumbar flexion. 2) Test for catheter patency by injecting sterile, preservative-free, normal saline through the catheter. 3) Radiological imaging to determine if a knot is present and to determine its location, using radiopaque contrast for patent catheters or a guidewire for occluded catheters. 4) The approach to definitive management is based on the position of the knot. This can range from excision under local anesthetic to consultation with a surgical specialty for more invasive retrieval.

Oxytocin receptor binding in rat and human heart.

OBJECTIVE: To determine whether cardiac oxytocin receptors are detectable by radioligand binding assay. Results from in vitro and in vivo animal studies suggest a possible direct effect of oxytocin on the cardiovascular system. DESIGN: A radioligand binding assay was used to characterize and quantify specific binding of [3H] oxytocin to standardized micropunches (thickness 400 microm; diameter 2 mm) obtained from rat left ventricle and human right atrium. Tissues from fetal and newborn rat heart were also studied. MAIN RESULTS: Saturable, high affinity binding of [3H] oxytocin to rat left ventricle was observed, consisting of a high affinity site (affinity [KD] approximately 1 nM; receptor density [Bmax] approximately 1480 fmol/mg protein) and a higher capacity, lower affinity site (KD approximately 75 nM; Bmax 3730 fmol/mg protein). Binding was displaceable by oxytocin, vasopressin and the agonist [Thr4, Gly7] oxytocin but not by the antagonist atosiban. Cardiac binding was reduced in ovariectomized (ie, estrogen-free) rats and increased in late gestation rats, when blood levels of ovarian steroids are maximal. Cardiac oxytocin receptors were undetectable in fetal and newborn rat heart. High concentrations of specific [3H] oxytocin binding were also found in samples of human right atrial appendage. CONCLUSIONS: These data confirm the presence of a specific oxytocin binding site in rat left ventricle and in human atrium. Binding density is regulated by ovarian steroids and is especially marked in the late stage of pregnancy. These observations provide an explanation for the putative direct effect of oxytocin on cardiac function.

Tourniquet inflation during arthroscopic knee ligament surgery does not increase postoperative pain.

PURPOSE: A double-blind clinical trial was conducted to determine the effect of inflation of a thigh tourniquet during anterior cruciate ligament repair on arthroscopic visibility, duration of procedure, postoperative pain and opioid consumption. METHODS: Thirty patients were randomly allocated into two groups; Group I had the thigh tourniquet inflated during surgery whereas the tourniquet was not inflated in Group II patients. All patients received standardized general anesthesia and postoperative pain management. Supplemental analgesia was provided with i.v. morphine via a patient-controlled analgesia (PCA) apparatus. Verbal pain rating scores (0-10) were obtained after surgery. RESULTS: Arthroscopic visibility was impaired in Group II patients (P < 0.0001), but this was ameliorated by increased irrigation flow or addition of epinephrine. Duration of surgery was similar in both groups. There was no difference between groups in postoperative morphine consumption (9.8 +/- 7.1 mg in Group I vs 11.4 +/- 10.2 mg in Group II) or in postoperative pain scores between groups. CONCLUSION: Inflation of a thigh tourniquet did not result in increased pain or opioid consumption after arthroscopic ACL surgery. Arthroscopic visibility was somewhat impaired in some patients without the use of tourniquet. Finally, the duration of the surgical procedure was not increased in patients where the tourniquet was not inflated during the ACL repair.

Pre-incision infiltration with lidocaine reduces pain and opioid consumption after reduction mammoplasty.

BACKGROUND AND OBJECTIVES: To determine the analgesic efficacy of preoperative tumescent infiltration with lidocaine for reduction mammoplasty. METHODS: Women with mammary hypertrophy were randomly allocated to one of two study groups in a double-blind clinical trial. Patients in group 1 received preincision infiltration with 5 mL/kg of 0.35% lidocaine with 1:1,000,000 epinephrine into each breast after induction of general anesthesia. Group 2 patients received similar injections of 5 mL/kg of saline with 1:1,000,000 epinephrine. Intravenous patient-controlled analgesia (PCA) morphine (1.0 mg bolus with 5-minute lockout) was available for 9.5 hours in the postoperative period. Visual analog pain scores were recorded during the postoperative period, and hourly morphine consumption data were retrieved from the PCA apparatus. Fitness for discharge was evaluated by the postanesthesia care unit nurse using standardized discharge criteria. RESULTS: Visual analog pain scores were higher in group 2 patients until 3.5 hours after surgery. Patients in the saline group had higher intravenous morphine consumption during all 1-hour postoperative intervals, although the differences between groups were statistically significant only until 4.5 hours after the operation. Total intravenous morphine consumption during the first 9.5 hours after surgery in group 1 was 16.9+/-11.9 mg versus 31.1+/-18.0 mg in group 2 (P < .05). Postoperative nausea and vomiting occurred with equal frequency (87%) in both study groups, and there was no difference between groups in time to achieve fitness for discharge, i.e., a postanesthesia discharge score of > or = 9. CONCLUSION: Preoperative tumescent infiltration with lidocaine results in reduced pain and lower postoperative opioid requirements in the initial hours after reduction mammoplasty.

Oxytocin injection after caesarean delivery: intravenous or intramyometrial?

PURPOSE: To determine, after Caesarean delivery, uterine contractility and blood pressure following intravenous (i.v.) and intramyometrial (imy) injection of oxytocin. METHODS: In a double-blind clinical trial 40 parturients scheduled for elective Caesarean section with spinal anaesthesia were randomized into two equal groups. One litre Ringer's lactate was administered i.v. before intrathecal injection of 1.7 ml bupivacaine 0.75% and 0.3 mg morphine. All patients received simultaneous i.v. and imy injections after removal of the placenta. Patients in Group 1 received 5 IU (10 IU.ml-1) oxytocin i.v. and 2 ml saline imy: Group 2 patients received 0.5 ml saline i.v. and 20 IU oxytocin into the myometrium. Baseline systolic blood pressure (SBP) and heart rate were measured before delivery and at one minute intervals for 15 min after injection of study solutions. Uterine contractility was assessed at 1, 2, 4, 6, 8, 10 and 15 min after oxytocin injection. Haemoglobin concentration before surgery and on first post-operative day was also recorded. RESULTS: Mean decrease in systolic blood pressure (SBP) one minute after oxytocin was 8.4 mmHg in Group vs 14.6 mmHg in Group 2 (P < 0.001). Systolic blood pressure returned to baseline two minutes after oxytocin in Group 1 and after three minutes in Group 2. Uterine contractility and change in haemoglobin concentration were similar in both groups. CONCLUSION: Intramyometrial administration of 20 IU oxytocin after Caesarean delivery is associated with more severe hypotension than is i.v. injection of 5 IU oxytocin. Route of oxytocin injection did not affect uterine tone.

Intrathecal catheter insertion during labour reduces the risk of post-dural puncture headache.

PURPOSE: To describe the anaesthetic management and report the incidence of PDPH in three parturients who had experienced accidental dural puncture during labour and the subsequent deliberate intrathecal insertion of an epidural catheter. CLINICAL FEATURES: Inadvertent dural puncture with a 16-gauge Tuohy needle occurred during the first stage of labour at 3-4 cm cervical dilatation in all three women. The 20-gauge epidural catheter was immediately inserted into the subarachnoid space after accidental dural penetration. Intermittent intrathecal injections of lidocaine or bupivacaine with fentanyl were administered to provide analgesia during labour and delivery. Two of the women had spontaneous vaginal deliveries, whereas Caesarean section was performed in one case due to acute fetal distress during the second stage of labour. The intrathecal catheter was left in-situ for 13-19 hr after delivery and the women were questioned daily for symptoms of PDPH. None of the three women developed PDPH after dural puncture and intrathecal catheterisation with the epidural catheter. CONCLUSION: Immediate intrathecal insertion of the epidural catheter after accidental dural puncture during labour proved to be an effective prophylactic technique to prevent PDPH in these three parturients.

The effect of oxytocin on the contractile force of human atrial trabeculae.

UNLABELLED: We performed an in vitro examination of the inotropic effect of oxytocin, chlorobutanol, and their combination to assess the effect of these drugs on the contractile force of human atrial trabeculae. Right atrial tissue samples were obtained during cardiac surgery with cardiopulmonary bypass. Trabeculae of the atrial appendage were dissected and mounted on muscle stands in a modified Krebs-Henseleit buffer bath. This isometric atrial trabecula preparation was subjected to a cumulative pharmacological protocol of either pure oxytocin, pure chlorobutanol, or a combination of the two drugs until no further change occurred in either developed force or resting force of the atrial trabeculae. A "no drug" buffer solution was used to assess the effect of time on the natural decay of the atrial preparation. The relative developed force of oxytocin plus chlorobutanol solution and pure chlorobutanol were similar in magnitude and lower than that in control experiments (P < 0.001) Pure oxytocin did not change the contractile force of atrial tissue. We conclude that pure oxytocin does not have a cardiodepressive effect in this human atrial preparation. Chlorobutanol has a negative inotropic effect, which is of a magnitude similar to a combined solution of chlorobutanol and oxytocin. Therefore, chlorobutanol added as a preservative to the commercial synthetic oxytocin solution may contribute to hypotension observed in patients after an intravenous bolus injection. IMPLICATIONS: We obtained specimens of heart tissue from patients undergoing cardiac surgery and conducted a laboratory study of the effects of oxytocin and its preservative (chlorobutanol) on these tissue samples. Chlorobutanol decreased the ability of the heart to contract, while as pure oxytocin had no effect. This explains why maternal blood pressure may decrease and provides impetus to produce oxytocin with another, safer preservative.

Peri-operative multimodal pain therapy for caesarean section: analgesia and fitness for discharge.

PURPOSE: To compare, the efficacy of a multi-modal analgesic regimen and single drug therapy with iv PCA morphine alter Caesarean delivery with spinal anaesthesia. METHODS: Forty ASA 1-2 parturients presenting for elective Caesarean section were randomized to receive multimodal pain treatment with intrathecal morphine, incisional bupivacaine and ibuprofen+acetaminophen po until hospital discharge (Group 1) or conventional therapy with iv PCA morphine weaned to acetaminophen+codeine po (Group 2). Both groups received spinal anaesthesia with 1.7 ml hyperbaric bupivacaine 0.75%. Visual analog pain scores at rest (RVAPS) and with movement (DVAPS) were recorded q 2 hr during the first 24 hr, then q 4 hr until discharge. Time to first walking, eating solid food, flatus, bowel movement, voiding and hospital discharge were recorded. RESULTS: Pain scores were lower in Group 1 patients during the first 24 hr after spinal injection RVAPS 0.6 +/- 0.1 in Group 1 vs 2.1 +/- 0.1 in Group 2 (mean +/- SEM), DVAPS 1.9 +/- 0.1 in Group 1 vs 4.1 +/- 0.1 in Group 2 (P < 0.0001). Times to first flatus, 36.1 hr +/- 2.9 vs 20.5 +/- 1.8 (P < 0.05) and to first bowel movement, 74.8 hr +/- 5.6 vs 57.4 +/- 4.7 (P < 0.0001) were longer in Group 2 patients. There was no difference between groups in time to eating solid food, walking or hospital discharge. CONCLUSION: Multi-modal pain therapy resulted in improved early post-operative analgesia during the first 24 hr after Caesarean delivery. Patients receiving iv PCA morphine followed by acetaminophen+codeine po were more likely to develop decreased bowel mobility. All patients, with one exception, achieved discharge criteria (eating solid food, absence of nausea, normal lochia, dry incision and DVAPS < 4) at 48 hr after spinal injection.

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 i.v. 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 occurred 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 i.v. 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.

Anaesthetic management of labour and delivery in the parturient with mitochondrial myopathy.

PURPOSE: We describe the anaesthetic management for Caesarean section in a parturient with a defect in complex III of the respiratory chain who had increased lactate concentrations at rest and with exercise. CLINICAL FEATURES: We administered effective epidural anaesthesia with lidocaine for Caesarean delivery. The serum lactate concentration was less than the preoperative value both during and after surgery. Shivering during the perioperative period was avoided by administering warm i.v. fluids, warm local anaesthetic solution and epidural meperidine. Pain relief after surgery was provided with i.v. PCA morphine augmented by local infiltration with bupivacaine to fascia and skin edges and epidural injection with meperidine. CONCLUSION: Mitochondrial myopathies are an uncommon group of disorders in which mitochondrial dysfunction leads to clinical disease of muscle and sometimes of other organs with high energy requirements. The management of labour and delivery in women with mitochondrial myopathies should be individualized according to severity of disease and formulated by consultation between attending physicians and the anaesthetist. Epidural analgesia reduces stress and work associated with labour and reduces oxygen demand during labour. However, parturients with defects of the respiratory chain with documented increased lactate concentrations at rest and with exercise are best managed with elective Caesarean delivery with regional anaesthesia to prevent life-threatening lactic acidosis during labour. The association between malignant hyperthermia and these disorders has not been proved, but it appears prudent to consider these women as MH susceptible until definitive data regarding this possible relationship are available.

Epidural opioid analgesia after caesarean section: a comparison of patient-controlled analgesia with meperidine and single bolus injection of morphine.

The quality of analgesia, patient satisfaction and incidence of side effects following a single bolus of epidural morphine were compared with patient-controlled epidural analgesia (PCEA) with meperidine during the first 24 hr after elective Caesarean section. Seventy-five women were randomly assigned to three equal groups. Group I received 30 mg epidural meperidine after delivery and PCEA with meperidine; Group 2 received 3 mg epidural morphine after delivery and PCEA with saline in a double-blind fashion. Group 3 received 3 mg epidural morphine after delivery without saline PCEA. Visual analogue pain scores (VAS) were higher with PCEA meperidine from 8-16 hr post-operatively (P < 0.05) than in both epidural morphine groups. Two patients in Group 1 and one in Group 3 required supplemental parental analgesia. The incidence of nausea was 16% in Group 1, compared with 52% in Group 2 and 56% in Group 3 (P < 0.01). Pruritus occurred in 24% of Group 1 patients, 84% of patients in Group 2 and 68% of patients in Group 3 (P < 0.001). Forty-six percent of patients in Group 1 were very satisfied with pain management, compared with 77% in Group 2 and 79% in Group 3. Nurse workload was higher in the PCEA study groups than in Group 3 (P < 0.05). A single bolus of epidural morphine provides superior analgesia and satisfaction at low cost, but with a higher incidence of nausea and pruritus than PCEA with meperidine.

The obstetrical anaesthesia assessment clinic: a review of six years experience.

We reviewed the out-patient consultation notes of 136 pregnant women seen at the Ottawa Civic Hospital from 1985 to 1991 to evaluate the efficacy of an Obstetric Anaesthesia Assessment Clinic (OAC). In addition, their anaesthetic records from labour and delivery were reviewed. For each patient the reason for referral was recorded according to the involved organ system. The anaesthetic management at delivery was compared with the proposed anaesthetic plan by the OAC consultant (obstetric anaesthetist). The majority of women 84 (62%) had complaints related to the musculo-skeletal system. In addition, 18 patients were referred because of previous anaesthetic problems, ten with a history of cardiac disease, and eight with neurological disease. Lumbar epidural analgesia (LEA) was a safe and effective choice for parturients with low back pain, history of lumbar fractures or single level discectomies without lumbar fusion. Parturients with posterior instrumentation experienced an increased incidence of inadequate pain relief from LEA. Individualized anaesthetic management plans were executed for parturients with spina bifida occulta, neurological, cardiac, and haematological disease as well as for women, with a history of adverse drug reactions and previous problems with regional or general anaesthesia. It is concluded that the OAC has provided a valuable service to obstetricians and anaesthetists for the anaesthetic management of pregnant women with co-existing disease. The OAC gave an opportunity for patient education regarding anaesthetic options for labour and delivery. The attending anaesthetist was provided with a risk assessment and anaesthetic management plan which was adhered to with only two exceptions. Finally, the obstetrician was given consistent advice regarding anaesthesia management that may affect obstetrical decisions.

Maternal and fetal effects of intravenous patient-controlled fentanyl analgesia during labour in a thrombocytopenic parturient.

The use of intravenous (i.v.) patient-controlled fentanyl analgesia during labour in a parturient with unexplained thrombocytopenia (70 x 10(3).ml-1) is described. The patient self-administered boluses of 25 micrograms of fentanyl with a lock-out interval of ten min. In addition, a concurrent fentanyl infusion of 25 micrograms.hr-1 was given. Effective analgesia was achieved during labour and a total of 1025 micrograms of fentanyl was infused over 11 hr 55 min until delivery of a vigorous infant with Apgar scores of 9 after one and five min. Respiratory depression or undue sedation were not observed in the mother either during labour or in the post-partum period. At birth, maternal total plasma fentanyl concentration was 1.11 ng.ml-1, whereas neonatal umbilical total plasma fentanyl concentration was 0.43 ng.ml-1. Newborn plasma protein binding of fentanyl was lower compared to the mother (63% vs 89%). Thus, free fentanyl concentrations (0.16 ng.ml-1) were identical in the mother and newborn at delivery.

Early respiratory depression during caesarean section following epidural meperidine.

A case of respiratory depression which occurred following administration of epidural meperidine during Caesarean section is described. Epidural meperidine, 75 mg (10 mg.ml-1) was given after delivery of the infant to provide postoperative analgesia. Oxygen desaturation (SaO2 90%) and a decrease in respiratory rate (4.min-1) were noted 30 min after epidural meperidine was administered. Naloxone, 0.1 mg, was given iv which resulted in prompt improvement in both respiratory rate and oxygen saturation. Vascular absorption of meperidine from the epidural venous plexus is the most probable explanation for this case of early respiratory depression. We recommend a maximum bolus dose of 50 mg of epidural meperidine for pain management after Caesarean section. It is also important to monitor oxygen saturation continuously during the intraoperative period, and to monitor the patient closely in the recovery room for at least one hour for evidence of respiratory depression.