Neuraxial opioids for post-cesarean delivery analgesia: can hydromorphone replace morphine? A retrospective study.

BACKGROUND: Cesarean delivery is the most common surgical procedure performed in the USA. We evaluated the postoperative analgesic properties of neuraxial hydromorphone compared to neuraxial morphine for post-cesarean delivery analgesia. METHODS: A retrospective chart review was performed of women who underwent cesarean delivery and received neuraxial anesthesia from March to November 2011 and from March to November 2012. A total of 450 patients received intrathecal morphine 200µg and 387 patients received intrathecal hydromorphone 60µg. Eighty-one patients received epidural morphine 3mg and 102 patients received epidural hydromorphone 0.6mg. RESULTS: Median time to first opioid after intrathecal morphine was 17.0h versus 14.6h after intrathecal hydromorphone (P<0.0001). Patients who received intrathecal hydromorphone consumed more opioids in the first 24h; 37.0mg versus 26.4mg oral morphine equivalents (P<0.001). The side effect profile between the intrathecal groups was similar. Median time to first opioid with epidural morphine was 20.1h versus 13.0h with epidural hydromorphone (P=0.0007). Total opioid consumption was not significantly different between the epidural groups. The side effect profiles were similar. CONCLUSIONS: Hydromorphone is a reasonable alternative to morphine for post-cesarean delivery analgesia. With the dosing used in our study, analgesia from morphine lasted longer than hydromorphone via intrathecal and epidural routes; however, neuraxial hydromorphone remains a reasonable option for long-acting analgesia post cesarean delivery.

Simultaneous analysis of 14 non-steroidal anti-inflammatory drugs in human serum by electrospray ionization-tandem mass spectrometry without chromatography.

A method is described for the simultaneous analysis of 14 non-steroidal anti-inflammatory drugs (NSAIDS) in human serum using negative electrospray ionization-tandem mass spectrometry (ESI-MS/MS). After addition of internal standard and protein precipitation using acetonitrile, samples were transferred to autosampler vials for direct analysis without chromatography. Injection of an air bubble with the sample and a multiple reaction monitoring (MRM) method using argon collision-induced dissociation (CID) of analyte (M-H)- ions permitted integration of the product ion peak areas to produce reproducible quantitative data over the range of concentrations expected in serum during routine use of these drugs. The method permitted the analysis of 30 samples per hour. Two hundred fifty consecutive analyses did not adversely affect instrument sensitivity.

Extraction of benzoylecgonine (cocaine metabolite) and opiates (codeine and morphine) from urine samples using the Zymark RapidTrace.

The Zymark RapidTrace automated solid-phase extraction system has been evaluated for use in the urine drug-testing laboratory. Methods for cocaine metabolite (benzoylecgonine) and opiates (codeine and morphine) are described and evaluated. The linearity, precision, accuracy, recovery, and carryover statistics of these analytical protocols are presented. The advantages of extraction using the RapidTrace instead of solid-phase extraction with the manual vacuum manifold or liquid-liquid extraction methods are described.

Limit for qualitative detection of benzoylecgonine in urine using EMIT reagents and the Hitachi 705 automatic analyzer.

The limit of detection for the cocaine metabolite (hydrolysis product), benzoylecgonine, using Syva EMIT reagents and the Hitachi 705 automatic analyzer has been found to be 10 ng/mL at the 99% confidence level. For this determination 30 controls were prepared from a single urine pool known to be negative for cocaine metabolite. Urine samples of 90 patients were found to be drug-free when analyzed by selected ion monitoring gas chromatography/mass spectrometry for ecgonine methyl ester and benzoylecgonine at sensitivities of less than 0.4 ng/mL and 1.3 ng/mL, respectively. To test matrix effects on the limit of detection, these samples were screened with the Hitachi 705. Results for eight of the known negative samples fell above the 10-ng/mL limit of detection while only one presumptive positive resulted at an arbitrary 20-ng/mL cutoff. Detection limits were also determined using 20 different negative patients' urine samples fortified with benzoylecgonine. At the 99% confidence level using EMIT d.a.u. and 705 reagents the detection limits were found to be 44 ng/mL and 35 ng/mL, respectively. It was found that 62% of patients' samples positive for benzoylecgonine fell below the 300-ng/mL cutoff and above a cutoff at 50 ng/mL.

Automated extraction of lysergic acid diethylamide (LSD) and N-demethyl-LSD from blood, serum, plasma, and urine samples using the Zymark RapidTrace with LC/MS/MS confirmation.

A forensic procedure for the quantitative confirmation of lysergic acid diethylamide (LSD) and the qualitative confirmation of its metabolite, N-demethyl-LSD, in blood, serum, plasma, and urine samples is presented. The Zymark RapidTrace was used to perform fully automated solid-phase extractions of all specimen types. After extract evaporation, confirmations were performed using liquid chromatography (LC) followed by positive electrospray ionization (ESI+) mass spectrometry/mass spectrometry (MS/MS) without derivatization. Quantitation of LSD was accomplished using LSD-d3 as an internal standard. The limit of quantitation (LOQ) for LSD was 0.05 ng/mL. The limit of detection (LOD) for both LSD and N-demethyl-LSD was 0.025 ng/mL. The recovery of LSD was greater than 95% at levels of 0.1 ng/mL and 2.0 ng/mL. For LSD at 1.0 ng/mL, the within-run and between-run (different day) relative standard deviation (RSD) was 2.2% and 4.4%, respectively.

Unilateral external fixation for corrective osteotomies in patients with hypophosphatemic rickets.

Extremity deformities in patients with hypophosphatemic rickets (HPR) are often complex and multiplanar. Described methods for correcting these deformities are imprecise and require interruption of the medical management of the condition. Corrective osteotomies were performed on 29 bones in nine children with HPR. Use of the Orthofix external fixator enabled precise correction of the deformities without interruption of medical management.

Extending the detection limit of the TDx fluorescence polarization immunoassay for benzoylecgonine in urine.

This modified calibration method decreases from 300 to 27 micrograms/L the limit of detection for the cocaine metabolite (hydrolysis product), benzoylecgonine, by the Abbott Laboratories TDx fluorescence polarization immunoassay. For this determination we used 30 controls prepared from a single urine pool known to be negative for cocaine metabolite. Assay of 80 controls prepared from 20 different patients' urine samples yielded a limit of detection of 44 micrograms/L. To test these limits of detection, we analyzed 90 patients' urine samples known to be negative for cocaine metabolite and 74 patients' samples known to be positive for cocaine metabolite, using the TDx with our revised calibration. Results for two of the known negative samples and 96% of the samples containing cocaine in the 50 to 100 micrograms/L range fell above the 44 micrograms/L limit. The TDx showed excellent calibration stability. For 28 days during the test, the instrument was not recalibrated. During this period the day-to-day analysis of 50 micrograms/L controls produced a mean TDx response of 0.485 (SD 0.007) with a coefficient of variation of 1.5%.

Tetrahydrobiopterin in the treatment of infantile hypertrophic pyloric stenosis.

Evidence is emerging that reduced nitric oxide production may be involved in the pathogenesis of hypertrophic pyloric stenosis. Nitric oxide synthase (NOS) requires tetrahydrobiopterin (BH4) for activity. Four infants with hypertrophic pyloric stenosis were treated with oral BH4 (10 mg/kg/day) for 2.5 days. Although plasma total biopterin increased significantly at 3, 27, and 51 h after BH4 administration, there was no effect on the production of plasma cGMP, nitrite, nitrate, or citrulline. Ultrasound investigations before and after the ingestion of BH4 revealed no changes in the hypertrophic pyloric stenosis. We conclude that oral BH4, in the dose utilized in our investigations, does not modify the cause of hypertrophic pyloric stenosis, presumably because it did not restore nitric oxide production in the nonadrenergic noncholinergic nerves of the enteric nervous system.

Comparison of bupivacaine, etidocaine, and saline for trigger-point therapy.

Injections of local anesthetics, saline, "dry needling," or other stimuli at specific, tender loci (trigger or acupuncture points) are reportedly efficacious in treatment of chronic pain syndromes. In a randomized, double-blind crossover study, subjective responses of 15 patients with myofascial syndrome to trigger-point injections of either bupivacaine 0.5%, etidocaine 1%, or physiologic saline without preservative were compared. Responses in six pain-related categories were determined before treatment and 15 minutes, 24 hours, and 7 days after treatment. Trigger-point injections with bupivacaine and etidocaine were generally preferred over saline in several pain-tested categories. Implications and possible mechanisms are discussed.

Acute cardiovascular effects of dimethylsulfoxide.

Dimethylsulfoxide (DMSO) has been advocated as a central nervous system (CNS) protectant against ischemia and trauma. The present study was performed to evaluate acute cardiovascular effects of DMSO which might complicate the clinical treatment of CNS compromised patients. Intravenously administered DMSO in doses which reportedly provide CNS protection, 2 g/kg, were infused in 6 dogs; hemodynamic variables were measured and compared to infusion of equal volumes of 0.9% sodium chloride. Immediately after infusion, DMSO caused increases in cardiac index, heart rate, pulmonary capillary wedge pressures (WP), and pulmonary arterial (systolic, mean, and diastolic) pressures which were significantly greater than changes induced by saline. DMSO decreased systematic diastolic pressure and systemic vascular resistance at the end of infusion. Most DMSO induced changes returned toward pre-infusion values 10 min after the end of infusion. These results suggest transient DMSO effects different from equal volumes of saline, possibly due to hyperosmotic expansion of plasma volume. A decrease in systemic vascular resistances was also observed. Although neither CNS production, intracranial pressure or blood flow were studied, these data suggest that DMSO used for CNS protection would not have adverse acute hemodynamic consequences. This may be particularly relevant in traumatized, hypovolemic patients.

High-frequency alternating lung ventilation.

A new mode, high-frequency alternating lung ventilation (HFALV) is described and demonstrated in which the lungs are alternately pulsed. A fluidic oscillator may be used to deliver two pulsed gas streams, 180 degrees out of phase, to bronchial catheters placed via a double lumen endobronchial tube. Inspiratory phase of one lung thus coincides with expiratory phase in the other, and characteristic lateral rocking chest movements is observed. In six dogs, HFALV was compared to simultaneous pulsing of both lungs with comparable flow (18.5 l/min), frequency (144 min-1), and pulse wave shape. Arterial PCO2 was significantly lower (P less than 0.001) with HFALV. Arterial PCO2 was also found to increase linearly (r = -0.862, P less than 0.001) with distance of the catheters' distal tips from the dogs' carinae. Theoretical mechanisms and possible applications of HFALV are discussed.