Operative and non-operative management for intestinal emergencies: findings from a single-centre retrospective cohort study

BACKGROUND

Patients with an intestinal emergency who do not have surgery are poorly characterised. This study used electronic healthcare records to provide a rapid insight into the number of patients admitted with an intestinal emergency and compare short-term outcomes for non-operative and operative management.

METHODS

A single-centre retrospective cohort study was conducted at a tertiary NHS hospital (from 1 December 2013 to 31 January 2020). Patients were identified using diagnosis codes for intestinal emergencies, based on the inclusion criteria for the National Emergency Laparotomy Audit. Relevant data were extracted from electronic healthcare records (n=3,997).

RESULTS

Nearly half of patients admitted with an intestinal emergency received nonoperative management (43.7%). Of those who underwent surgery, 63.7% were started laparoscopically. The non-operative group had a shorter hospital stay (median: 5.4 days vs 8.2 days [started laparoscopically] or 16.8 days [started open]) and fewer unintended intensive care admissions than the surgical group (2.4% vs 8.7% [started laparoscopically] 21.1% [started open]). However, 30-day mortality for non-operative treatment was double that for surgery (22.4% vs 10.1%). The 30-day mortality rate was found to be even higher for non-operative management (50.3%) compared with surgery (19.5%) in a sub-analysis of patients with admission National Early Warning Score ≥4 (n=683).

CONCLUSION

The proportion of patients with intestinal emergencies who do not have surgery is greater than expected, and it appears that many respond well to non-operative treatment. However, 30-day mortality for non-operative management was high, and the low number of admissions to intensive care suggests that major invasive treatment was not appropriate for most in this group.

Quench, Normal Zone Propagation Velocity, and the Development of an Active Protection Scheme for a Conduction Cooled, R&W, MgB2 MRI Coil Segment

The development of coils that can survive a quench is crucial for demonstrating the viability of MgB₂-based main magnet coils used in MRI systems. Here we have studied the performance and quench properties of a large (outer diameter: 901 mm; winding pack: 44 mm thick × 50.6 mm high) conduction-cooled, react-and-wind (R&W), MgB₂ superconducting coil. Minimum quench energy (MQE) values were measured at several coil operating currents (I _op ), and distinguished from the minimum energy needed to generate a normal zone (MGE). During these measurements, normal zone propagation velocities (NZPV) were also determined using multiple voltage taps placed around the heater zone. The conduction cooled coil obtained a critical current (I _c ) of 186 A at 15 K. As the operating currents (I _op ) varied from 80 A to 175 A, MQE ranged from 152 J to 10 J, and NZPV increased from 1.3 to 5.5 cm/s. Two kinds of heater were involved in this study: (1) a localized heater ("test heater") used to initiate the quench, and (2) a larger "protection heater" used to protect the coil by distributing the normal zone after a quench was detected. The protection heater was placed on the outside surface of the coil winding. The test heater was also placed on the outside surface of the coil at a small opening made in the protection heater. As part of this work, we also developed and tested an active protection scheme for the coil. Such active protection schemes are of great interest for MgB₂-based MRIs because they permit exploitation of the relatively large MQE values of MgB₂ to enable the use of higher J _e values which in turn lead to competitive MgB₂ MRI designs. Finally, the ability to use a quench detection voltage to fire a protection heater as part of an active protection scheme was also demonstrated.

Comparison of the National Early Warning Score in non-elective medical and surgical patients

BACKGROUND

The National Early Warning Score (NEWS) is used to identify deteriorating patients in hospital. NEWS is a better discriminator of outcomes than other early warning scores in acute medical admissions, but it has not been evaluated in a surgical population. The study aims were to evaluate the ability of NEWS to discriminate cardiac arrest, death and unanticipated ICU admission in patients admitted to surgical specialties, and to compare the performance of NEWS in admissions to medical and surgical specialties.

METHODS

Hospitalwide data over 31 months, from adult inpatients who stayed at least one night or died on the day of admission, were analysed. The data were categorized as elective or non-elective surgical or medical admissions. The ability of NEWS to discriminate the outcomes above in these different groups was assessed using the area under the receiver operating characteristic curve (AUROC).

RESULTS

There were too few outcomes to permit meaningful comparison of elective admissions, so the analysis was constrained to comparison of non-elective admissions. NEWS performed equally well, or better, for surgical as for medical patients. For death within 24 h the AUROC for surgical admissions was 0·914 (95 per cent c.i. 0·907 to 0·922), compared with 0·902 (0·898 to 0·905) for medical admissions. For the combined outcome of any of death, cardiac arrest or unanticipated ICU admission, the AUROC was 0·874 (0·868 to 0·880) for surgical admissions and 0·874 (0·871 to 0·877) for medical admissions.

CONCLUSION

NEWS discriminated deterioration in non-elective surgical patients at least as well as in non-elective medical patients.

Demonstration of a Conduction Cooled React and Wind MgB2 Coil Segment for MRI Applications

This study is a contribution to the development of technology for an MgB₂-based, cryogen-free, superconducting magnet for an MRI system. Specifically, we aim to demonstrate that a react and wind coil can be made using high performance in-situ route MgB₂ conductor, and that the conductor could be operated in conduction mode with low levels of temperature gradient. In this work, an MgB₂ conductor was used for the winding of a sub-size, MRI-like coil segment. The MgB₂ coil was wound on a 457 mm ID 101 OFE copper former using a react-and-wind approach. The total length of conductor used was 330 m. The coil was epoxy impregnated and then instrumented for low temperature testing. After the initial cool down (conduction cooling) the coil I_c was measured as a function of temperature (15-30 K), and an I_c of 200 A at 15 K was measured.

Virologic and Immunologic Impact and Durability of Enfuvirtide-Based Antiretroviral Therapy in HIV-Infected Treatment-Experienced Patients in a Clinical Setting

OBJECTIVE

To evaluate the effectiveness and safety of enfuvirtide-based therapy in treatment-experienced patients in a clinical setting.

METHOD

Retrospective study of treatment-experienced patients receiving enfuvirtide-based therapy for a minimum of 2 months. Endpoints included virologic suppression, virologic rebound, immunologic response, and adverse events.

RESULTS

Sixty-four patients were eligible for inclusion in the analysis. Median baseline viral load and CD4+ count were 4.7 log10 copies/mL (interquartile range [IQR], 4.0-5.2) and 150 cells/mm3 (IQR, 60-250), respectively. At month 12, viral load declined by a median of 2.53 log10 copies/mL (IQR, 0.97-3.12). The unadjusted median time to virologic suppression was 7.7 months (95% CI 4.1-10.4 months). Baseline viral load and number of protease inhibitors in the current regimen were significantly associated with virologic suppression following multivariate analysis (hazard ratio [HR] 0.45, 95% CI 0.31-0.63, p < .0001, and HR 0.51, 95% CI 0.27-0.94, p = .03, respectively). Among the 42 patients who attained sustained virologic suppression, 10 experienced virologic rebound during a median follow-up of 13.3 months (IQR, 7.0-19.1). Injection site reactions were reported in 33 (52%) patients, resulting in treatment discontinuation in nine patients.

CONCLUSION

Enfuvirtide-based therapy provides durable antiretroviral activity for treatment-experienced patients in a clinical setting.

A role for mucosal IL-22 production and Th22 cells in HIV-associated mucosal immunopathogenesis

Interleukin-22 (IL-22) is a cytokine with epithelial reparative and regenerative properties that is produced by Th22 cells and by other immune cell subsets. Therefore, we explored the hypothesis that disruption of the gut barrier during HIV infection involves dysregulation of these cells in the gastrointestinal mucosa. Sigmoid IL-22-producing T cell and Th22 cells were dramatically depleted during chronic HIV infection, epithelial integrity was compromised, and microbial translocation was increased. These alterations were reversed after long-term antiretroviral therapy. While all mucosal IL-22-producing T-cell subsets were also depleted very early during HIV infection, at these early stages IL-22 production by non-T-cell populations (including NKp44+ cells) was increased and gut epithelial integrity was maintained. Circulating Th22 cells expressed a higher level of the HIV co-receptor/binding molecules CCR5 and α4β7 than CD4+ T-cell subsets in HIV-uninfected participants, but this was not the case after HIV infection. Finally, recombinant IL-22 was protective against HIV and tumor necrosis factor-α-induced gut epithelial damage in a validated in vitro gut epithelial system. We conclude that reduced IL-22 production and Th22 depletion in the gut mucosa are important factors in HIV mucosal immunopathogenesis.

Virologic and immunologic effectiveness of tipranavir/ritonavir (TPV/r)- versus darunavir/ritonavir (DRV/r)-based regimens in clinical practice

BACKGROUND

Although both tipranavir and darunavir are important options for the management of patients with multidrug resistant HIV, there are at present no studies comparing the effectiveness and safety of these 2 antiretroviral drugs in this population of patients.

OBJECTIVE

To compare the effectiveness and safety of ritonavir (TPV/r)- and darunavir/ritonavir (DRV/ r)-based therapies in treatment-experienced patients (n = 38 and 47, respectively).

METHODS

Multicenter, retrospective cohort study.

RESULTS

The median baseline viral load and CD4 count were 4.7 copies/mL (interquartile range [IQR] 4.3, 5.2) and 168 cells/mm( 3) (IQR 80, 252) for TPV/r patients and 4.7 copies/mL (IQR 3.7, 5.1) and 171 cells/mm(3) (IQR 92, 290) for DRV/r patients. The median number of years on antiretroviral therapy (ART) prior to starting DRV/r or TPV/r were 12.7 (10.2-15.5) and 10.5 (8.4-12.6), respectively (P < .01). Current raltegravir (RAL) use (odds ratio [OR] 5.53, 95% CI 1.08-28.34) was significantly associated with virologic suppression at week 24 in multivariable logistic regression models, whereas the use of TPV/r was not significantly associated with virologic suppression compared to DRV/r (OR 0.93, 95% CI 0.27-3.18, P = .91).

CONCLUSION

No significant difference was observed between DRV/r and TPV/r in terms of virologic suppression.

Prevalence of community-associated methicillin-resistant Staphylococcus aureus colonization in men who have sex with men

Summary

Outbreaks of skin and soft tissue infections mediated by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are being reported with increasing frequency among men who have sex with men (MSM). However, the potential role of asymptomatic colonization with this organism in perpetuating these infections is unclear. The purpose of this cross-sectional study was to determine the prevalence of colonization with CA-MRSA among a cohort of 500 MSM recruited from two inner city clinics in Toronto, Canada. Following the provision of informed consent, subjects completed a questionnaire capturing demographic and clinical variables, which may be associated with MRSA colonization. A nasal swab for MRSA was collected from each subject, and instructions were provided regarding the self-collection of a rectal swab. Cultured MRSA underwent pulsed-field gel electrophoresis and virulence testing for Panton-Valentine leukocidin gene expression. The prevalence of CA-MRSA colonization was 1.6% (95% CI: 0.5–2.6%).

Is there a reservoir of sub-clinical lymphogranuloma venereum and non-LGV Chlamydia trachomatis infection in men who have sex with men?

SUMMARY

The aim of this study was to determine if a reservoir of sub-clinical LGV infection exists in men who have sex with men (MSM), as this finding might account for the recent rise in lymphogranuloma venereum (LGV) Chlamydia trachomatis infections among MSM in Canada. MSM without proctitis were enrolled between January and August 2006 in a cross-sectional study. Rectal, urine, serology and pharyngeal specimens were tested for specific C. trachomatis serovars. The median age of the 253 participants was 43 years; 53% were HIV+. We found no active cases of LGV infection; but 20 (8%) participants had positive serology. Thirteen participants (5%) had non-LGV C. trachomatis infections. Unprotected anopenetrative intercourse, rectal enema and drug use were associated with non-LGV C. trachomatis infection. Sub-clinical rectal non-LGV C. trachomatis infection was relatively common but LGV was not identified in our sample. Further studies of screening for non-LGV chlamydia infection in MSM are needed.

A large prospective study assessing injection site reactions, quality of life and preference in patients using the Biojector vs standard needles for enfuvirtide administration

OBJECTIVES

To determine the severity of injection site reactions (ISRs), patient quality of life (QoL) and preference when enfuvirtide is administered by the Biojector (Bioject, Medical Technologies, Inc., Tualatin, OR, USA) relative to standard needles.

METHODS

A total of 201 HIV-positive patients on stable enfuvirtide-based therapy (n=184) or initiating such therapy (n=17) were evaluated prospectively after switching from standard needles to the Biojector system. Patients used needles for a minimum of 2 weeks prior to switching to the Biojector. Questionnaires to assess the incidence and severity of ISRs (31-item score) and QoL [Medical Outcomes Study HIV Health Survey (MOS-HIV)] were administered at baseline and following a minimum of 14 days of Biojector use.

RESULTS

The median changes in ISR score and number of ISRs following a median of 1.0 month [interquartile range (IQR) 0.9, 1.3] of Biojector use were -3 (IQR -7, 1) and -1 (IQR -3, 1), respectively. The severity of pain (P<0.0001), induration (P<0.0001), pruritus (P<0.0001), nodules (P<0.0001) and erythema (P<0.0001) all decreased with the Biojector. Administration of enfuvirtide with the Biojector was associated with an improved patient QoL (P<0.0001), and was preferred by 72% of patients.

CONCLUSIONS

Compared with needles, the Biojector was associated with a decreased severity of ISRs and improved QoL in patients taking enfuvirtide.

Risk factors for grade 3-4 liver enzyme elevation in HIV and hepatitis C coinfected patients on combination antiretroviral therapy

Although coinfection with hepatitis C (HCV) is an established risk factor for hepatotoxicity in HIV-positive patients receiving combination antiretroviral therapy (cART), specific variables that may be predictive of severe hepatotoxicity among co-infected patients receiving cART remain poorly defined. A retrospective cohort study of HIV/HCV coinfected adults from two HIV treatment centers covering the period between December 1998 and December 2003 was conducted to address this question. The primary endpoint of the study was the occurrence of grade 3 or 4 elevation of serum alanine aminotransferase (ALT) during follow-up and the primary predictors of interest were specific antiretrovirals. One hundred five coinfected patients receiving cART for a median of 70 months (interquartile range [IQR], 37, 83) were included in the analysis. Twenty-three (22%) patients developed a grade 3 or 4 increase in serum ALT at least once in follow-up. In univariate analysis, current receipt of lopinavir/ritonavir (LPV/r) (odds ratio [OR] 3.09, 95% confidence interval [CI] 1.14-8.34, p = 0.03), baseline ALT (OR 1.01, 95% CI 1.00-1.02, p = 0.004), and current use of boosting ritonavir (OR 2.84, 95% CI 1.16-7.00, p = 0.02) were significantly associated with a grade 3 or 4 increase in serum ALT, although most patients receiving boosting ritonavir were on lopinavir/ritonavir based regimens. Patients receiving LPV/r had been previously exposed to significantly more antiretrovirals (p < 0.0001), protease inhibitors (p < 0.0001), and nucleoside analogues (p = 0.0009) compared to the rest of the cohort. Further research to better clarify risk factors for hepatotoxicity in coinfected patients is warranted given the challenges in treating this population.

Quantitative and qualitative assessment of human immunodeficiency virus type 1 (HIV-1)-specific CD4+ T cell immunity to gag in HIV-1-infected individuals with differential disease progression: reciprocal interferon-gamma and interleukin-10 responses

The human immunodeficiency virus type 1 (HIV-1)-specific CD4(+) T cell response was investigated in 33 untreated HIV-1-infected individuals, using highly sensitive ELISPOT assays and intracellular flow cytometry. The median frequencies of interferon (IFN)-gamma-producing HIV-1 gag-specific CD4(+) T cells did not correlate significantly with control of viral replication or progression. HIV-1 gag-specific interleukin (IL)-4-producing cells were rarely detected. Circulating frequencies of CD4(+) T cells constitutively producing IL-10, however, were significantly higher in individuals with progression or active replication. In 17 of 30 HIV-1-infected individuals, gag antigen was observed to induce IL-10 production from CD4(+) T cells. In 2 individuals, early treatment of acute HIV-1 infection "rescued" low to undetectable gag-specific IFN-gamma-producing CD4(+) T cell responses and dramatically down-regulated constitutive IL-10 production from circulating CD4(+) T cells. The detection of HIV-1-specific IL-10-inducing CD4(+) T cells in HIV-1-infected individuals suggests that HIV-1 may directly subvert specific immune responses by IL-10 induction.

Transient relapses ("blips") of plasma HIV RNA levels during HAART are associated with drug resistance

INTRODUCTION

In a large number of patients on HAART who achieved plasma HIV RNA levels below the limit of detection (50 copies/ml), transient relapses of HIV RNA levels ("blips") are observed.

OBJECTIVE

To determine whether relapses of plasma HIV RNA during HAART are associated with development of drug resistance.

METHODS

Plasma samples from 15 patients with a transient viral load relapse during HAART were studied. All regimens contained lamivudine (3TC). We used an ultrasensitive sequence approach to analyze the presence of drug resistance mutations during the relapse.

RESULTS

The median plasma HIV RNA load of the relapse was 76 copies/ml (range 50-1239). In 11 of 15 cases, a genotype of HIV could be obtained. Mutations in the RT and protease gene conferring resistance to one or more drugs were observed in 8 of 11 patients, 6 of whom had the M184V substitution. During a median follow-up of 27 months after the relapse, plasma HIV RNA levels remained undetectable in 13 of 15 patients.

CONCLUSIONS

Plasma HIV RNA blips during HAART can be associated with selection of drug-resistant HIV. This indicates that viral replication may occur during HAART, probably caused by a temporary decrease in active drug concentrations. A blip containing only wild-type virus is not necessarily caused by viral replication. In this situation the raise of HIV RNA could also originate from release of wild-type viruses, caused by activation of the latent virus reservoir. Independent of the mechanism, blips did not preclude successful inhibition of viral replication during 2-year follow-up in the majority of these cases.

Factors contributing to the lack of human immunodeficiency virus type 1 (HIV-1) transmission in HIV-1-discordant partners

Correlates of resistance to infection by human immunodeficiency virus type 1 (HIV-1) are important for defining potential therapeutic interventions and for prophylactic vaccination. In this study, 11 couples discordant in their HIV-1 infection status were prospectively evaluated for the presence of protective factors. Behavioral characteristics of all subjects entailed a high risk of transmission. Cytotoxic T lymphocyte (CTL) responses against viruses isolated from the infected partner, and against laboratory virus isolates, were detected in 5 (45%) of 11 HIV-negative partners, including a CCR5Delta32-homozygous and a heterozygous subject. No CTL responses were observed in 6 control unexposed subjects. Marked variation in lymphocyte susceptibility to viral infection was noted. Resistance attributable to major histocompatibility complex discordance or anti-major histocompatibility complex antibodies was not identified. These results suggest that a combination of factors, including cellular immunity, viral characteristics, and coreceptor integrity, may be involved in the persistent nontransmission of HIV.

The avian lung: is there an aerodynamic expiratory valve?

The unidirectional gas-flow pattern through the avian lung is thought to result from 'aerodynamic valves'; support for this hypothesis lies mainly in the failure to find any evidence for anatomical valves. During expiration, air flows from the caudal air sacs through the major exchange area of the lung, the paleopulmonic parabronchi, instead of bypassing the lungs via the intrapulmonary bronchus. We tested whether the effectiveness of this expiratory flow control mechanism depends on aerodynamic factors, especially convective inertial forces that depend on gas density and flow velocity. In pump-ventilated, anaesthetized geese, a bolus of tracer gas was introduced into both the right and left caudal thoracic air sacs during an end-inspiratory pause. During the first expiration, the rise of tracer levels within the caudal trachea was measured. Valve efficacy was positively correlated with the rate of expiratory gas flow, V&middot;ao (range 8&shy;200 ml s-1). At flows assumed to occur during exercise in geese (V&middot;ao&gt;100 ml s-1), the expiratory valve efficacy was approximately 95 %; it was less effective at lower flows. Surprisingly, the density (rho) of the background gas (rho of He/O2=0.43 g l-1, Ar/O2=1.72 g l-1 or SF6/O2=5.50 g l-1) had no effect on expiratory valving. We suggest two possible mechanisms that might explain this unusual combination of flow dependence without density dependence. (1) If airway geometry changes occurred between experiments with different gases, flow in the vicinity of the expiratory valve may have varied independently from flow measured at the airway opening. (2) Alternatively, valving may depend on dynamic compression of the intrapulmonary bronchus, which could depend mainly on viscous resistance and thus on flow velocity but not gas density.