Relation between hospital surgical volume and outcome for pancreatic resection for neoplasm in a publicly funded health care system

BACKGROUND

Recent studies from the United States have shown that institutions with higher numbers of pancreatic resection procedures for neoplasm have lower mortality rates associated with this procedure. However, minimal work has been done to assess whether the results of similar volume-outcome studies within a publicly financed health care system would differ from those obtained in a mixed public-private health care system.

METHODS

A population-based retrospective analysis was used to examine pancreatic resection for neoplasm in Ontario for the period 1988/89 to 1994/95. Outcomes examined included in-hospital case fatality rate and mean length of stay in hospital. For each hospital, total procedure volume for the study period was defined as low (fewer than 22), medium (22-42) or high (more than 42). Regression models were used to measure volume-outcome relations.

RESULTS

The likelihood of postoperative death was higher in low-volume and medium-volume centres than in high-volume centres (odds ratio 5.1 and 4.5 respectively; p < 0.01 for both). Mean length of stay was greater in low- and medium-volume centres than in high-volume centres (by 7.7 and 9.2 days respectively, p < 0.01 for both).

INTERPRETATION

This study adds to growing evidence that, for pancreatic resection for neoplasm, patients may have better outcomes if they are treated in high-volume hospitals rather than low-volume hospitals.

A prospective quantitative study of sensory deficits after whole sural nerve biopsies in diabetic and nondiabetic patients. Surgical approach and the role of collateral sprouting

BACKGROUND

Sural nerve biopsy (Sbx) has been employed for the diagnosis of peripheral neuropathies and for multicenter trials of therapy in diabetic neuropathy. There is only limited prospective information available about what factors influence the resolution of the sensory deficit (Sdef) after biopsy.

METHODS

We prospectively studied the surface area of skin Sdef after whole human Sbx in diabetic and nondiabetic patients for up to 18 months after the procedure. Sdef was determined by mapping, in two dimensions, the area of loss to pinprick and light touch in the sural distribution using a transparent boot-like device with 1-square-cm grid markings. At the same time, patients were interviewed about biopsy-related symptoms.

RESULTS

Overall, the Sdef in all patients declined by an average of 91 +/- 3% at 18 months. The pattern of Sdef decline indicated that collateral sprouting was the mechanism of sensory reinnervation. The extent of Sdef at 6, 12, or 18 months did not differ between diabetics and nondiabetics. In diabetics, there was a correlation between sensory reinnervation with pre-biopsy sural nerve potential amplitude and HbA1C level, but not with age or diabetes duration. Diabetic patients who had nerve resections starting at or below the center of a plane through the lateral malleolus and traveling proximally for 7 cm or less had a Sdef that was less than patients with longer and more proximal nerve resections. The majority of patients had unpleasant but mild mechanically elicited sensory symptoms at 1 year that had improved in most, but not all patients, by 18 months.

CONCLUSIONS

Sbx is associated with prolonged sensory symptoms and sensory loss. Recovery occurs by collateral reinnervation.

Local human sural nerve blood flow in diabetic and other polyneuropathies

Microangiopathy is considered relevant to the pathogenesis of several forms of peripheral nerve disease, particularly diabetic polyneuropathy. In diabetes, however, it is uncertain whether reductions in mixed nerve trunk blood flow account for early features of polyneuropathy in contrast to later disease, where microvascular changes have been described. To address this issue, we measured local sural nerve blood flow in patients with mild diabetic polyneuropathy who were enrolled in a clinical trial (n = 26), patients with other polyneuropathies being studied by diagnostic sural nerve biopsy (n = 17), patients with vasculitic polyneuropathy (n = 3) and one patient with rapidly progressive severe diabetic polyneuropathy and lumbosacral plexopathies. Standardized measurements were made at 10 sites along the sural nerve of each patient prior to sural nerve resection for biopsy. We used a laser Doppler flowmetry probe sensitive to red blood cell flux to measure sural nerve blood flow. This was slightly higher in patients with mild diabetes compared with those with other polyneuropathies, but was reduced in patients with vasculitis. In patients with mild diabetes, there was no relationship between sural nerve blood flow and prebiopsy sural nerve action-potential amplitude, sural myelinated fibre density, haemoglobin A1C, duration of diabetes or age of the patient. Ten diabetic patients entered in the clinical trial had sural nerve blood flow recorded in one sural nerve, followed 1 year later by a second sural nerve blood flow measurement prior to biopsy of the contralateral sural nerve. Despite a mild trend toward decline in fibre density between the nerves over this period of time, sural nerve blood flow was similar. The patient with severe diabetic polyneuropathy and lumbosacral plexopathies had reduced sural nerve blood flow. Our findings do not provide evidence that reductions in sural nerve blood flow are associated with early peripheral neuropathy in diabetes, unlike vasculitis. The early trend toward slight rises in sural nerve blood flow may be a result of early functional microangiopathy that accompanies nerve dysfunction but does not cause it.

Peptides and neuromas: calcitonin gene-related peptide, substance P, and mast cells in a mechanosensitive human sural neuroma

We examined and compared a mechanosensitive human sural neuroma and a contralateral sural nerve collected simultaneously from a patient involved in a diabetic neuropathy research protocol. Using indirect immunofluorescence staining. we identified a striking difference in the content within axons of two neuropeptides, substance P (SP) and calcitonin, gene-related peptide (CGRP), between the contralateral nerve and the neuroma. Unlike the contralateral nerve, where immunofluorescence was sparse, a significant number of disorganized axon profiles that stained brightly positive for CGRP or SP were identified in the neuroma. In contrast, staining for tyrosine hydroxylase, a label of sympathetic axons, was largely absent except around one large arteriole. The neuroma specimen also contained large numbers of serotonin-containing mast cells, only noted occasionally in the contralateral nerve. The peptide staining and mast cell accumulation in the human neuroma closely resembled changes we have previously observed in an animal neuroma model. Local neuropeptides may play a role in the injury response of peripheral nerve, and may be related to mechanosensitivity.

Analysis of diethyltoluamide (DEET) following intentional oral ingestion of Muscol

N,N-Diethyl-m-toluamide (DEET) is an effective component of several insect repellent products. A 19-year-old woman was admitted to the emergency department following ingestion of 15-25 mL 95% diethyltoluamide (Muscol). Serum and urine toxicology screening tests were negative except for detection of DEET. DEET was qualitatively identified and quantitated by gas chromatography-mass spectrometry. Concentrations of DEET based on selected ion monitoring (ion at m/z 119) were 63.0, 17.2, 1.9, and less than 0.2 mg/L in serum specimens collected at 2, 5, 24, and 48 h following ingestion, respectively. Serial monitoring of DEET concentrations and the cardiac abnormalities observed in this case following oral ingestion were not reported previously.