Identification of myocardial injury using perioperative troponin surveillance in major noncardiac surgery and net benefit over the Revised Cardiac Risk Index

BACKGROUND

Patients with perioperative myocardial injury are at risk of death and major adverse cardiovascular and cerebrovascular events (MACCE). The primary aim of this study was to determine optimal thresholds of preoperative and perioperative changes in high-sensitivity cardiac troponin T (hs-cTnT) to predict MACCE and mortality.

METHODS

Prospective, observational, cohort study in patients ≥50 yr of age undergoing elective major noncardiac surgery at seven hospitals in Sweden. The exposures were hs-cTnT measured before and days 0-3 after surgery. Two previously published thresholds for myocardial injury and two thresholds identified using receiver operating characteristic analyses were evaluated using multivariable logistic regression models and externally validated. The weighted comparison net benefit method was applied to determine the additional value of hs-cTnT thresholds when compared with the Revised Cardiac Risk Index (RCRI). The primary outcome was a composite of 30-day all-cause mortality and MACCE.

RESULTS

We included 1291 patients between April 2017 and December 2020. The primary outcome occurred in 124 patients (9.6%). Perioperative increase in hs-cTnT ≥14 ng L^-1 above preoperative values provided statistically optimal model performance and was associated with the highest risk for the primary outcome (adjusted odds ratio 2.9, 95% confidence interval 1.8-4.7). Validation in an independent, external cohort confirmed these findings. A net benefit over RCRI was demonstrated across a range of clinical thresholds.

CONCLUSIONS

Perioperative increases in hsTnT ≥14 ng L^-1 above baseline values identifies acute perioperative myocardial injury and provides a net prognostic benefit when added to RCRI for the identification of patients at high risk of death and MACCE.

CLINICAL TRIAL REGISTRATION

NCT03436238.

Introduction of a rapid sequence induction checklist and its effect on compliance to guidelines and complications

BACKGROUND

Current evidence for the conduct of rapid sequence induction (RSI) is weak. This increases the risk of clinicians modifying the RSI procedure according to personal preferences. Checklists may help increase compliance to best practice guidelines and reduce complication rates. Their value during RSI, a critical procedure in anaesthesia, is unknown. The aim of this study was to investigate compliance to local guidelines and frequency of RSI-related complications before and after introduction of an RSI checklist.

METHODS

This was a prospective, observational, pre- and post-intervention study conducted at two hospitals. There were two interventions: the first was a standardized educational lecture to all staff at both hospitals, consisting of an educational instruction of the checklist and general information about RSI, and the second intervention was the introduction of a RSI checklist. The checklist consisted of 16 items. Compliance to guidelines was categorized as high, moderate and low, and was assessed pre- and post-intervention. The frequency of RSI-related complications was also measured.

RESULTS

We registered 811 RSI procedures of which 412 were pre-intervention. After intervention, the proportion of procedures with high compliance to RSI guidelines increased from 49% to 70% (P < .001). The proportion with partial and low compliance decreased from 37% to 26% (P < .001) and 13% to 3.3% (P < .001) respectively. No change in RSI-related complication rates was detectable post-intervention (16.6%-16.7% P = .56).

CONCLUSION

The introduction of a structured RSI checklist significantly increased compliance to RSI guidelines. A change in RSI-related complications could not be detected due to the size of the study. A checklist may be a useful tool to reduce variance during the RSI procedure.

Angiography and Colour Flow Duplex Ultrasonography in the Evaluation of Peripheral Ischaemic Occlusive Arterial Disease

Colour flow duplex ultrasonography (CFDUS) was performed in 50 patients with advanced peripheral ischaemic disease scheduled for conventional angiography. Atherosclerosis was diagnosed by the appearance of plaque and spectral broadening. Haemodynamically significant stenosis was represented as a doubling of peak systolic velocity expressed as peak velocity ratio. Occlusion was diagnosed by the lack of colour saturation and absence of Doppler wave form. In the pelvis and thigh/knee region the sensitivity and specificity exceeded 90% except for stenoses, where the sensitivity was lower. The run-off was evaluated by examination of the tibial and peroneal arteries to at least midcalf. If 2 open arteries were identified, or, if only the posterior tibial artery was patent, the run-off was considered good. Compared to angiography the sensitivity and specificity exceeded 90%. We conclude that CFDUS is an accurate non-invasive method for preoperative screening of patients with peripheral ischaemic disease.

Cost-effectiveness of colour duplex sonography compared with angiography of the pelvis and lower limb

The present investigation was performed to assess the clinical consequences, utility and efficacy of colour duplex sonography (CDS) compared with angiography as a preoperative examination in aorta, pelvis and lower limb, and thus to estimate the cost-effectiveness of CDS. CDS was additionally performed in 53 consecutive patients referred for preoperative angiography of the lower limb. The results for 49 patients were reviewed and compared to assess the technique's clinical utility. The costs of the two methods and the consequences of inappropriate treatment were assessed. In 15 patients inadequate diagnoses were obtained at CDS. If surgery had been performed solely on the basis of the ultrasonographic diagnosis, repeat surgery would have been necessary in 9 patients. In a further 3 patients necessary surgery would not have been performed. Two patients would have been overtreated (unnecessary surgery instead of percutaneous transluminal balloon angioplasty). To correct the initial incorrect diagnosis the estimated yearly cost would be approximately 1.3 million Swedish crowns. In addition, complications and discomfort could be anticipated for the patients. Because of its low sensitivity CDS ist not cost-effective as a preoperative investigation of arteries of the pelvis and lower limb.

Angiography and colour flow duplex ultrasonography in the evaluation of peripheral ischaemic occlusive arterial disease

Colour flow duplex ultrasonography (CFDUS) was performed in 50 patients with advanced peripheral ischaemic disease scheduled for conventional angiography. Atherosclerosis was diagnosed by the appearance of plaque and spectral broadening. Haemodynamically significant stenosis was represented as a doubling of peak systolic velocity expressed as peak velocity ratio. Occlusion was diagnosed by the lack of colour saturation and absence of Doppler wave form. In the pelvis and thigh/knee region the sensitivity and specificity exceeded 90% except for stenoses, where the sensitivity was lower. The run-off was evaluated by examination of the tibial and peroneal arteries to at least midcalf. If 2 open arteries were identified, or, if only the posterior tibial artery was patent, the run-off was considered good. Compared to angiography the sensitivity and specificity exceeded 90%. We conclude that CFDUS is an accurate non-invasive method for preoperative screening of patients with peripheral ischaemic disease.

Aspects of abstinence after morphine ingestion

Sprague-Dawley male rats were intoxicated with morphine, using an ingestion method where exposed and control rats received equivalent amounts of calories and nutrients. The degree of physical dependence on morphine was demonstrated by studying and quantifying abstinence symptoms after withdrawal or after administration of opiate antagonists. The aims of the study were (1) to further enlighten the specificity and validity of the intoxication method concerning physical dependence, and (2) to determine whether some of the abstinence signs might be of value to facilitate quantitation of the degree of physical dependence on morphine, with diet and fluid intake being maintained under control. Withdrawn rats showed a decreased fluid diet intake and a body weight loss, the latter partly due to anorexia. Other mild abstinence signs were irritation, tremor and some motor excitation. The body weight loss during the first day of morphine withdrawal was proportional to the accumulated drug dose (between 25 and 300 mg morphine PO/kg b.wt.). However, prolonged morphine treatment on one dose (340 mg/kg b.wt.) did not reinforce the body weight changes caused by morphine withdrawal. The succeeding weight gain some days after morphine withdrawal was not entirely dependent on the amount of fluid diet intake. Methadone was shown to partially block the decrease in diet intake and the weight loss seen during morphine withdrawal. The naloxone-precipitated withdrawal symptoms were motor excitation, cholinergic signs, body weight loss, diarrhoea and decreased diet intake. The weight loss 2 hr after naloxone administration to long-term intoxicated rats was proportional to the naloxone dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurotransmitter uptake in various brain regions of chronically morphinized rats

Rats were long-term morphine-intoxicated by a fluid-diet model ensuring an equal nutrient intake in morphinized and control rats. Uptake of neurotransmitters and D-ala2-met5-enkephalinamide (Enk) was studied in the particulate fractions (obtained at 10,000 g) from well defined brain regions of long-term intoxicated and morphine withdrawn rats. In control animals the accumulation of [3H]glutamate and [3H]gamma-aminobutyric acid (GABA) reached the highest tissue/medium (T/M) ratio values, 30-120, in the regions studied while monoamine T/M values were 2-10. No active uptake of [3H]Enk could be demonstrated. Striatum showed the most evident modifications in neurotransmitter uptake. In this region the equilibrium T/M ratio for [3H]glutamate and [3H]GABA was significantly lower in intoxicated rats versus controls. Moreover, the T/M ratio for [3H]5-hydroxytryptamine (5-HT) was lower, while that for [3H]dopamine (DA) was higher in abstinent rats in comparison with the controls. [3H]glutamate and [3H]GABA uptakes were also significantly lower, respectively, in frontal cortex, hippocampus and brain stem in intoxicated rats, while [3H]5-HT uptake was significantly lower in hypothalamus after morphine withdrawal. The possible involvement of the endogenous opioid system in the etiology of the alterations is discussed.

Decreased morphine intake by opiate addicted rats administered zimelidine, a 5-HT uptake inhibitor

Zimelidine, a specific 5-HT uptake inhibitor, reduced peroral morphine consumption by morphine-addicted adult male and female Sprague-Dawley rats and old male rats in choice tests. The effect was dose dependent in male rats. Thus, the availability of central 5-HT appears to be important for the regulation of morphine preference in rat. The results are discussed in relation to recent literature where ethanol preference has been found to be attenuated by zimelidine. The results may provide insights into the complex cellular mechanisms underlying opiate addiction.

A new ingestion method for long-term morphine intoxication in rat

A new method for long-term morphine intoxication in rat was developed. It was designed to deal with the nutritional imbalance and body weight loss that generally occurs using conventional techniques for morphine treatment. The morphine is administered in a nutritionally complete diet. Also pair-feeding is used to deal with intoxicated rats that do not eat the same amount of food as controls. The technique was validated during the study of different intoxication conditions, using different initial doses, dose increments and final doses. An initial dose of 25 mg morphine/kg b.w., raised exponentially up to 340 mg/kg b.w. in 8 days, made the rats dependent, as tested by withdrawal signs, precipitated by excluding morphine from the diet, or by administration of antagonists. A final dose of up to 715 mg morphine/kg b.w. was reached in 13 days without decreased food intake. However, initial doses of 340 or 715 mg/kg led to impaired weight gain and diet consumption. Plasma morphine levels of 3 micrograms/ml serum were reached on a dose of 340 mg/kg b.w. Also, preference for morphine diet over control diet was evaluated by choice tests. The technique is simple, time-saving and inexpensive, allowing the treatment of numerous animals for long periods under standardized intoxication conditions. No animals get ill or die.

Soluble protein and peptide pattern from different regions of rat brain during pre- and early postnatal development

Isotachophoretic pattern from phylogenetically different regions of rat brain during pre- and early postnatal development were studied. Four main observations were made: a) The patterns were greatly similar during maturation of the respective regions studied; b) One complex of peaks disappeared or decreased in quantity during the 2nd and 3rd weeks of postnatal development; c) New peaks appeared and accumulated during the same period; d) Slight differences were observable in the different regions studied.