Publications

We compared the relative sensitivity of computed tomography (CT) and myelography for identification of disk herniation in dogs. Criteria for patient selection included presurgical CT, myelography, or both and surgical or necropsy confirmation of disk herniation between the T3 and L6 vertebral articulations. Imaging findings were described as positive or inconclusive. Adverse events such as hypotension, cardiac arrhythmias, seizures, death, and lower urinary tract infection were compared between imaging groups. One hundred and eighty-two dogs met the inclusion criteria, with 116 dogs having myelography performed as the initial diagnostic imaging modality and 66 dogs having CT performed as the initial modality. The relative sensitivity for locating the site of disk herniation was 83.6% when myelography was the first test performed and 81.8% when CT was the first test performed. CT was more sensitive than myelography at detecting lesions in chronically affected dogs (P = 0.025). Myelography was more sensitive than CT at detecting lesions in smaller dogs (< 5 kg; P = 0.004). Dogs that received both imaging modalities were significantly more likely to die or be euthanized compared with myelography alone (P < 0.001). Both myelography and CT are reasonable diagnostic imaging modalities for locating the site of disk herniation. CT should be considered especially in heavier, more chronically affected dogs. The major limitations of this study include lack of randomization to imaging modality and the use of surgical exploration or necropsy as the gold standard.

BACKGROUND

Vancomycin area-under-the-concentration-time-curve (AUC) for 24 hours divided by the minimum inhibitory concentration (MIC) (AUC24/MIC) >400 optimally treats invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in adults. It is unknown whether recommended vancomycin dosing regimens for children achieve this value.

METHODS

AUC24/MIC was calculated in children using vancomycin doses of 40 and 60 mg/kg/d. AUC24 was calculated as daily dose/vancomycin clearance. Vancomycin clearance in children was estimated by 2 approaches: (1) previously literature-reported vancomycin clearance, and (2) calculated vancomycin clearance using previously derived predictor models and a hypothetical population of healthy children. Representative MIC of hospital MRSA isolates was used (0.5, 1.0, and 2.0 microg/mL).

RESULTS

The MIC50/90 for pediatric MRSA isolates in the previous year was 1.0 microg/mL. With a dose of 40 mg/kg/d, both approaches consistently predicted AUC24/MIC <400 when MIC was 1.0 microg/mL. At 60 mg/kg/d, AUC24/MIC >400 was more readily achieved when MIC was 1.0 microg/mL, however, an MIC of 2.0 microg/mL resulted in AUC24/MIC <400 for both dosing regimens.

CONCLUSIONS

A vancomycin dose of 40 mg/kg/d in children is unlikely to achieve the recommended pharmacodynamic target of AUC24/MIC >400 for invasive MRSA infections even when MIC is 1.0 microg/mL. A starting dose of 60 mg/kg/d should be used in settings where isolates with MIC of 1.0 are common. Alternatives to vancomycin should strongly be considered for patients with MIC > or =2.0 microg/mL.

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) are known to have an increased risk for motor vehicle crashes. They suffer from sleep-related respiratory abnormality causing repetitive arousal leading to daytime sleepiness. In turn, it has been demonstrated that sleepiness can impair human psychomotor performance causing slowing of reaction times (RTs). Patients with OSAS present with RTs comparable to young adults under the influence of blood alcohol concentrations above the legally permitted level to drive a motor vehicle. Vigilance related risk levels in patients with upper airway resistance syndrome (UARS) and potential deficits in psychomotor performance are unknown.

METHODS

We designed a study to compare psychomotor performance in UARS and compared it to patients with OSAS. Forty-seven UARS patients were matched by gender and age with 47 OSAS patients. All subjects completed a standardized vigilant attention task utilizing reaction time before undergoing polygraphic sleep studies.

RESULTS

Patients with UARS presented worse psychomotor performance on most test metrics than patients with OSAS.

CONCLUSIONS

Our study results may suggest that patients with UARS may also present an increased risk for motor vehicle crashes as previously demonstrated in OSAS patients.