Lower incidence of post-dural puncture headache with spinal catheterization after accidental dural puncture in obstetric patients.

BACKGROUND: Accidental dural puncture (ADP) and post-dural puncture headache (PDPH) are important complications of obstetric regional anesthesia. Inserting the catheter intrathecally after ADP to prevent PDPH has gained popularity. Nonetheless, data on the effect of an intrathecal catheter on PDPH and epidural blood patch (EBP) rates are mixed. Our primary objective was to examine if spinal catheterization reduces the incidence of PDPH after ADP in obstetric patients. METHODS: Anesthetic records of 29,749 regional blocks performed between January 1997 and July 2013 were analyzed retrospectively. In all blocks containing an epidural component, 18-gauge epidural needles were used. All patients who experienced a witnessed ADP or PDPH without ADP were identified. Data from patients with or without a prolonged spinal catheter were compared. RESULTS: There were 128 events of witnessed ADP (0.43%). Following known ADP, 39 women had an epidural catheter placed at a different level and 89 had an intrathecal catheter (20-gauge) for at least 24 h. Sixty-one patients developed PDPH after observed ADP (48%). Prolonged intrathecal catheter placement significantly reduced the incidence of PDPH after ADP to 42% compared with 62% in those who have the catheter re-sited epidurally [odds ratio = 2.3 (95% confidence interval 1.04-4.86); P = 0.04]. CONCLUSIONS: The incidence of ADP, PDPH and blood patching is similar with previously published studies. After witnessed ADP, inserting the epidural catheter intrathecally significantly reduced the incidence of PDPH.

Acute intrathecal haematoma following neuraxial anaesthesia: diagnostic delay after apparently normal radiological imaging.

We describe a case of intrathecal haematoma following combined spinal-epidural anaesthesia for caesarean section. The parturient was previously well with no risk factors for haematoma development. Surgical intervention was delayed, resulting in permanent neurological injury. Incorrect interpretation of clinical findings and magnetic resonance imaging contributed to the delay in definitive treatment. We discuss the difficulties in diagnosis, image interpretation and the need for a specialist opinion when abnormal neurological symptoms persist despite apparently normal imaging.

S K- and Mo L-edge X-ray absorption spectroscopy to determine metal-ligand charge distribution in molybdenum-sulfur compounds.

Mo L-edge and S K-edge X-ray absorption spectroscopy were applied to investigate the charge distribution between Mo and S in a series of Mo thiolate compounds, which serve as amide-sulfur H-bonding models and exhibit different redox potentials arising from polar group effects and ligand hydrogen bonds near the redox center. For all oxidized complexes, the S K-edge spectra exhibit a thiolate-based pre-edge feature centered at 2470.2 eV and the inflection point oCCurs at 2472.0 eV. No intense pre-edge feature is observed in the spectra for the reduced Mo model compounds and the energy shift of the S K-edge position depends on the S-ligand. Correlations between ligand charge density and the redox potential of the Mo-S cores are observed.

Titanium alkoxide complexes: condensed phase and gas phase comparisons.

The complex [Ti(2,4-dimethyl-2,4-pentanediolate)2]2 (1) has been synthesized from [Ti(OiPr)4] by transesterification with a stoichiometric amount of 2,4-dimethyl-2,4-pentanediol. We have characterized complex 1 in the solid state by single-crystal X-ray diffraction and in the gas phase by desorption chemical ionization mass spectrometry (DCI-MS). The structural and mass spectrometric data show complex 1 to be stable as a dimer in both the solid and gas phases. The retention of dimeric nuclearity in the gas phase sets complex 1 apart from other simple titanium alkoxide complexes [Ti(OiPr)4] and [Ti(OMe)4]4 that give rise to respective families of molecular ions in the DCI-MS experiment. The highest mass molecular ions for Ti alkoxide complexes in the gas phase may reveal the highest nuclearity that these complexes achieve in condensed phases. According to this interpretation the complex [Ti(OiPr)4] is principally dimeric in the gas phase and probably also in the pure liquid phase and should be represented by the formula [Ti(OiPr)4]2.

Determination of the mineral phases and structure of the bone-implant interface using Raman spectroscopy.

The bone-implant interface formed in a canine distal femur was examined by means of a Raman microprobe using an implant model designed to test calcium phosphate surface coatings. By using the 960 cm-1 band of calcium phosphate to characterize the interface and adjacent mineral, we obtained spatial and compositional information about the attachment of bone to the synthetic calcium phosphate coating on a titanium support. The interface between bone and the synthetic calcium phosphate is approximately 30-40 microns in width.

Molecular structure at the bone-implant interface: a vibrational spectroscopic characterization.

Test implant plates surgically retrieved from distal femurs of dogs were studied by Raman spectroscopy in order to characterize the bone-implant interface. The implant surface consisted of phosphate mineral, plasma sprayed on a titanium substrate. On the basis of its spectroscopic signature, the phosphate mineral of bone and the implant surface formed a mixed phase in the interface.

A Raman and infrared spectroscopic investigation of biological hydroxyapatite.

Raman spectra were acquired on ox femur samples treated with hydrazine to remove the organic components of bone. A large increase in the signal-noise ratio of the mineral spectrum resulted from the exposure of the mineral surface and the removal of fluorescent components of the organic matrix. The effect of hydrazine treatment of the mineral matrix has been reinvestigated and shown to be slight on the basis of second derivative FTIR data. This is the first time that this high resolution technique has been applied to biological minerals.

Resonance raman spectroscopic studies of axial ligation in oxyhemoglobin, oxymyoglobin, and nitrosylmyoglobin.

Raman intensity measurements for the Fe-O2 stretching band of HbO2 (Hb = hemoglobin) have been used to construct an excitation profile, which shows that resonance enhancement occurs mainly via the B and Q transition; no contribution is detectable from an out-of-plane charge-transfer transition. Direct coupling of VFe-O2 to the porphyrin pi-pi* transitions is explained on the basis of competition between the pi* orbitals of porphyrin and O2 for Fe d pi electrons. The RR spectrum of MbNO (Mb = myoglobin) at pH 8.4 is due solely to six-coordinate heme--NO, but lowering the pH to 5.8 converts the RR spectrum to one characteristic of five-coordinate heme--NO, consistent with Fe-ImH (ImH = imidazole) dissociation via protonation. The Fe-NO stretching frequencies are at 553 and 596 cm-1 for the high- and low-pH forms, as expected, but the low-pH form shows an additional 15NO-sensitive band, at 573 cm-1, which is assigned to Fe-N-O bending in the five-coordinate complex. The RR spectrum of MbO2 shows a shoulder at approximately 270 cm-1, which shifts down by approximately 3 cm-1 upon 18O2 substitution, and is suggested to contain the Fe-ImH stretching mode. The weakness of VFe-ImH, relative to VFe-O2, is attributable to the lack of ImH involvement in the heme pi bonding.

Transcutaneous oxygen monitoring during exercise stress testing.

Transcutaneous oxygen tension (tcPO2) was compared with simultaneous arterial oxygen tension (PaO2) in 3 normal young adults and 4 pediatric lung disease patients at rest and during exercise to assess the usefulness of tcPO2 monitoring during exercise stress testing. At rest, the regression coefficient of tcPO2 on PaO2 was 0.78 +/- 0.03 (SEM) (r = 0.924; P < 0.0005). During exercise, the regression coefficient of tcPO2 on PaO2 was 0.88 +/- 0.02 (r = 0.958; P < 0.0005), indicating that tcPO2 approximates PaO2 equally well at rest and during exercise. After a step change in inspired oxygen concentration (FIO2) from 0.21 to 0.17, there was no significant difference in the tcPO2 time constant at rest (66.2 +/- 8.5 s) and during exercise (73.0 +/- 3.1 s). Neither PaO2 nor tcPO2 fell in normal subjects during graded exercise stress testing. However, in 3 of 4 pediatric lung disease patients, there were decreases in both PaO2 (40.7 +/- 11.6 Hg) and tcPO2 (28.7 +/- 10.0 mm Hg) during 7 exercise stress tests. These results indicate that tcPO2 approximates PaO2 equally well at rest and during exercise.