The Marsden Morbidity Index: the derivation and validation of a simple risk index scoring system using cardiopulmonary exercise testing variables to predict morbidity in high-risk patients having major cancer surgery

Background

Morbidity and mortality risk prediction tools are increasingly being used as part of preoperative assessment of patients presenting for major abdominal surgery. Cardiopulmonary exercise testing (CPET) can predict which patients undergoing major abdominal surgery are at risk of complications. The primary objective of this study was to identify preoperative variables including those derived from CPET, which were associated with inpatient morbidity in high-risk patients following major abdominal cancer surgery. The secondary objective was to use these variables to derive and validate a morbidity risk prediction tool.

Methods

We conducted a retrospective cohort analysis of consecutive adult patients who had CPET as part of their preoperative work-up for major abdominal cancer surgery. Morbidity was a composite outcome, defined by the Clavien-Dindo score and/or the postoperative morbidity survey (POMS) score which was assessed on postoperative day 7. A risk prediction tool was devised using variables from the first analysis which was then applied prospectively to a matched cohort of patients.

Results

A total of 1398 patients were included in the first phase of the analysis between June 2010 and May 2017. Of these, 540 patients (38.6%) experienced postoperative morbidity. CPET variables deemed significant (p < 0.01) were anaerobic threshold (AT), maximal oxygen consumption at maximal exercise capacity (VO2 max), and ventilatory equivalent for carbon dioxide at anaerobic threshold (AT VE/VCO2). In addition to the CPET findings and the type of surgery the patient underwent, eight preoperative variables that were associated with postoperative morbidity were identified. These include age, WHO category, body mass index (BMI), prior transient ischaemic attack (TIA) or stroke, chronic renal impairment, diabetes mellitus, chronic obstructive pulmonary disease (COPD), and cancer stage. Both sets of variables were then combined to produce a validated morbidity risk prediction scoring tool called the Marsden Morbidity Index. In the second phase of the analysis, this tool was applied prospectively to 424 patients between June 2017 and December 2018. With an area under the curve (AUC) of 0.79, this new model had a sensitivity of 74.2%, specificity of 78.1%, a positive predictive value (PPV) of 79.7%, and a negative predictive value of (NPV) of 79%.

Conclusion

Our study showed that of the CPET variables, AT, VO2 max, and AT VE/VCO2 were shown to be associated with postoperative surgical morbidity following major abdominal oncological surgery. When combined with a number of preoperative comorbidities commonly associated with increased risk of postoperative morbidity, we created a useful institutional scoring system for predicting which patients will experience adverse events. However, this system needs further validation in other centres performing oncological surgery.

[Community-acquired Staphylococcus aureus pneumonia]

We report a clinical case of a patient hospitalized for community-acquired Staphylococcus aureus pneumonia. A 26-year-old patient with no medical history went to the emergency department for fever. He quickly developed acute respiratory failure and community-acquired Staphylococcus aureus pneumonia as well as bacteremia were confirmed. This pulmonary infection is rare but can affect all age groups and occur in a variety of ways. Patients with community-acquired Staphylococcus aureus pneumonia have more severe clinical outcomes than those with community-acquired pneumonia caused by other germs. The article discusses the main characteristics of community-acquired Staphylococcus aureus pneumonia and recalls the recommendations in case of bacteremia with Staphylococcus aureus.

Electroretinograms to checkerboard pattern reversal in cats: physiological characteristics and effect of retrograde degeneration of ganglion cells

Pattern electroretinograms (P-ERGs) evoked by alternating checks were studied in cats. Spatial frequency functions for transient and steady-state P-ERG waves showed a bimodal distribution with a preferred frequency at 0.6-0.75 c/deg and a second amplitude increase at frequencies lower than 0.5 c/deg. Decreasing the pattern luminance by 0.5 log units produced a shift of the spatial tuning curve toward lower spatial frequencies. No temporal tuning was noted in the temporal frequency functions. The bimodal distribution suggests that at spatial frequencies higher than 0.5 c/deg, the tuning reflects a 'contrast response' originating in cells with center surround organization. At spatial frequencies below 0.5 c/deg, the 'luminance response' becomes predominant and is generated in cells sensitive to mean luminance changes. Transient and steady-state P-ERGs to medium and high spatial frequencies were abolished by section of the optic nerve, while low spatial frequency stimuli at or below 0.3 c/deg continued to evoke P-ERGs at 1, 5 and 10 months after surgery. Quantitative whole mount retina microscopic examination confirmed the retrograde degeneration of the ganglion cells. It is concluded that both transient and steady-state P-ERGs to small and medium spatial frequencies checks are predominantly related to ganglion cell activity, while P-ERGs to low spatial frequencies reflect preganglionic cell activity.

Effects of age and sex on pattern electroretinograms and visual evoked potentials

Pattern-electroretinograms (P-ERGs) and visual evoked potentials (VEPs) were simultaneously recorded in 112 normal individuals aged 20-75. Two-sized checks subtending 15' and 31' were used as stimuli. A weighted regression analysis was used to determine which of the variables, sex or age, was significant. The latency of the a and b wave of the P-ERGs showed a progressive increase with age but no difference between sexes. The effect was statistically significant for both 15' and 31' checks. There was no statistically significant aging effect for VEPs elicited by 31' checks. Aging, however, affected N70, P100, and the interpeak interval between b wave to N70 and b wave to P100 for responses to 15' checks. Shorter VEP latencies were noted in females for both 15' and 31' checks. The simultaneous recording of P-ERGs and VEPs has demonstrated that aging is a major variable at the retinal level. The effects on the a and b waves are mostly due to optic changes with aging and only partially to aging changes in the neuronal retinal circuitry. The effect of aging on VEPs is different for different size stimuli. The cause is a random neuronal cell loss in the visual pathways from the optic nerve to the visual cortex as the individual ages. The difference in VEP data between sexes may be related to anatomical size and hormonal influences.

Caffeine and tremor

Two percent of normal controls noted that drinking coffee made their hands shaky. Eight percent of essential tremor and 6% of Parkinson's disease patients thought that coffee worsened their tremor. In formal tests, a single oral dose of caffeine (325 mg) did not increase physiologic, essential tremor, or parkinsonian tremor at 1, 2, or 3 hours after ingestion. Caffeine only infrequently induces tremor in normal people, and it does not exacerbate pathologic tremor.

Disability in essential tremor: effect of treatment

We studied 18 patients with essential tremor for difficulty with handwriting, drinking, eating, fine manipulations, and embarrassment. Propranolol and primidone reduced the amplitude of both postural and kinetic tremor. Handwriting, drinking, and eating were improved with therapy, but fine manipulations and motor performance on tapping and pegboard tests were unaltered. Embarrassment remained unchanged. Essential tremor is not a benign condition; disability can be only partly reversed with drug therapy.

Clonidine in the treatment of essential tremor

The effect of clonidine treatment (average dose 0.4 mg/day) was investigated in 10 patients with essential tremor in a double-blind placebo-controlled design. Tremor amplitude and frequency were recorded with an accelerometer. Tremor was not significantly altered by clonidine therapy. Side effects were common. It is concluded that clonidine is not effective treatment for essential tremor.