Clinical outcomes from out-of-hospital cardiac arrest in low-resource settings - A scoping review

AIM OF THE SCOPING REVIEW

Scientific recommendations on resuscitation are typically formulated from the perspective of an ideal resource environment, with little consideration of applicability in lower-income countries. We aimed to determine clinical outcomes from out-of-hospital cardiac arrest (OHCA) in low-resource countries, to identify shortcomings related to resuscitation in these areas and possible solutions, and to suggest future research priorities.

DATA SOURCES

This scoping review was part of the continuous evidence evaluation process of the International Liaison Committee on Resuscitation (ILCOR), and was performed following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews. We identified low-resource countries as countries with a low- or middle gross national income per capita (World Bank data). We performed a literature search on outcomes after OHCA in these countries, and we extracted data on the outcome. We applied descriptive statistics and conducted a post-hoc correlation analysis of cohort size and ROSC rates.

RESULTS

We defined 24 eligible studies originating from middle-income countries, but none from low-income regions, suggesting a reporting bias. The number of reported patients in these studies ranged from 54 to 3214. Utstein-style reporting was rarely used. Return of spontaneous circulation varied from 0% to 62%. Fifteen studies reported on survival to hospital discharge (between 1.0 and 16.7%) or favourable neurological outcome (between 1.0 and 9.3%). An inverse correlation was found for study cohort size and the rate of return of spontaneous circulation (ρ = -0.48, p = 0.034).

CONCLUSION

Studies of OHCA outcomes in low-resource countries are heterogeneous and may be compromised by reporting bias. Minimum cardiopulmonary resuscitation standards for low-resource settings should be developed collaboratively involving local experts, respecting culture and context while balancing competing health priorities.

Changes in Case-Mix and Outcomes of Critically Ill Patients in an Australian Tertiary Intensive Care Unit

Critical care service is expensive and the demand for such service is increasing in many developed countries. This study aimed to assess the changes in characteristics of critically ill patients and their effect on long-term outcome. This cohort study utilised linked data between the intensive care unit database and state-wide morbidity and mortality databases. Logistic and Cox regression was used to examine hospital survival and five-year survival of 22,298 intensive care unit patients, respectively. There was a significant increase in age, severity of illness and Charlson Comorbidity Index of the patients over a 16-year study period. Although hospital mortality and median length of intensive care unit and hospital stay remained unchanged, one- and five-year survival had significantly improved with time, after adjusting for age, gender, severity of illness, organ failure, comorbidity, ‘new’ cancer and diagnostic group. Stratified analyses showed that the improvement in five-year survival was particularly strong among patients admitted after cardiac surgery (P=0.001). In conclusion, although critical care service is increasingly being provided to patients with a higher severity of acute and chronic illnesses, long-term survival outcome has improved with time suggesting that critical care service may still be cost-effectiveness despite the changes in case-mix.

Effect of length of stay in intensive care unit on hospital and long-term mortality of critically ill adult patients

BACKGROUND

Critical illness leading to prolonged length of stay (LOS) in an intensive care unit (ICU) is associated with significant mortality and resource utilization. This study assessed the independent effect of ICU LOS on in-hospital and long-term mortality after hospital discharge.

METHODS

Clinical and mortality data of 22 298 patients, aged 16 yr and older, admitted to ICU between 1987 and 2002 were included in this linked-data cohort study. Cox's regression with restricted cubic spline function was used to model the effect of LOS on in-hospital and long-term mortality after adjusting for age, gender, acute physiology score (APS), maximum number of organ failures, era of admission, elective admission, Charlson's co-morbidity index, and diagnosis. The variability each predictor explained was calculated by the percentage of the chi(2) statistic contribution to the total chi(2) statistic.

RESULTS

Most hospital deaths occurred within the first few days of ICU admission. Increasing LOS in ICU was not associated with an increased risk of in-hospital mortality after adjusting for other covariates, but was associated with an increased risk of long-term mortality after hospital discharge. The variability on the long-term mortality effect associated with ICU LOS (2.3%) appeared to reach a plateau after the first 10 days in ICU and was not as important as age (35.8%), co-morbidities (18.6%), diagnosis (10.9%), and APS (3.6%).

CONCLUSIONS

LOS in ICU was not an independent risk factor for in-hospital mortality, but it had a small effect on long-term mortality after hospital discharge after adjustment for other risk factors.

Effect of an episode of critical illness on subsequent hospitalisation: a linked data study

Healthcare utilisation can affect quality of life and is important in assessing the cost-effectiveness of medical interventions. A clinical database was linked to two Australian state administrative databases to assess the difference in incidence of healthcare utilisation of 19,921 patients who survived their first episode of critical illness. The number of hospital admissions and days of hospitalisation per patient-year was respectively 150% and 220% greater after than before an episode of critical illness (assessed over the same time period). This was the case regardless of age or type of surgery (i.e. cardiac vs non-cardiac). After adjusting for the ageing effect of the cohort as a whole, there was still an unexplained two to four-fold increase in hospital admissions per patient-year after an episode of critical illness. We conclude that an episode of critical illness is a robust predictor of subsequent healthcare utilisation.

Upper limb corticomotor projections and physiological changes that occur with botulinum toxin-A therapy in children with hemiplegic cerebral palsy

AIM

To investigate the corticomotor projection to the upper limb in children with hemiplegic cerebral palsy (CP) and the changes that occur with botulinum toxin (BTX)-A.

METHODS

The study design is a pilot prospective randomized trial. Twenty-two children with hemiplegic CP aged 7 years to 13 years 11 months were recruited. Treatment group (12) received one series of BTX-A injections into the upper limb. Control group (10) did not receive upper limb BTX-A. All participants except one treatment group participant also received lower limb BTX-A. Transcranial magnetic stimulation (TMS) was performed at baseline, and 1, 3 and 6 months post-injection. Outcome measures were: change in position of affected and unaffected side first dorsal interosseous optimal site of stimulation (OPTx).

RESULTS

A shift in affected and unaffected side OPTx was observed for both treatment and control groups, and there was no statistically significant difference between groups at 1, 3 or 6 months. Poor tolerance of TMS cortical stimuli >80% was observed.

CONCLUSION

Corticomotor projections associated with the upper limb in children with hemiplegic CP show significant variability over a 6-month period. This variability may reflect central motor reorganization because of systemic BTX-A effect or developmental changes. Upper limb BTX-A therapy is associated with reorganization of both affected and unaffected projections. Poor tolerance of the TMS procedure, in conjunction with higher cortical thresholds, may limit the usefulness of TMS as an investigatory tool in young children with movement disorders.

Data linkage enables evaluation of long-term survival after intensive care

Outcomes of intensive care are important to the patient and for assessment of benefit. Short-term outcomes after critical illness are well described, but less is known about long-term outcomes. This study describes the use of data linkage, combining intensive care unit (ICU) clinical data with administrative morbidity and mortality data, to assess long-term outcomes after treatment in ICU. The hospital-based cohort study was conducted in a 22-bed general ICU in a metropolitan teaching hospital. All patient admissions admitted to ICU from 1 January 1987 to 31 December 2002 were included. The prospective ICU clinical database with patient demographics, ICU diagnoses, severity of illness, daily assessment of organ failures and common daily treatments used was linked using probabilistic methods to the state-wide hospital morbidity and mortality databases to describe long-term survival. There were 26,019 ICU admissions (22,980 patients) with 25,972 records (99.8%) linked to a hospitalization event that included the index ICU admission. Unadjusted survival was 84.7% at 1 year decreasing progressively to 50.7% at 15 years. Age, type of admission, severity of illness (measured by Acute Physiologic and Chronic Health Evaluation (APACHE) II and the presence of organ failure), ICU length of stay, comorbidity (Chronic Health Evaluation and Charlson comorbidity index) and ICU admission diagnosis, were all associated with survival at 1, 3, 5, 10, and 15 year follow-up (P<0.001 at all time points). Linkage of clinical and administrative data provides a feasible method for ascertaining long-term survival after critical illness. Age, admission severity of illness, diagnosis and comorbidity influenced long-term unadjusted survival.

Outcomes of out-of-hospital cardiac arrest patients in Perth, Western Australia, 1996-1999

STUDY OBJECTIVE

To describe the epidemiology and survival from out-of-hospital cardiac arrest.

DESIGN

Longitudinal follow-up study from the time of paramedic attendance to 12 months later.

SETTING

Perth, Western Australia (WA), a metropolitan capital city with an adult population of approximately one million people.

METHOD

The St John Ambulance Australia (WA Ambulance Service Incorporated) cardiac arrest database was linked to the WA hospital morbidity and mortality data using probabilistic matching.

INCIDENCE

Of 3730 cardiorespiratory arrests in 1996-1999, the age standardised rate of arrests of presumed cardiac origin, where resuscitation was attempted (n=1293) was 32.9 per 100000 person-years and 7.1 per 100000 person-years for bystander-witnessed VF/VT arrests.

SURVIVAL

Survival to 28 days was 6.8% following all bystander-witnessed cardiac arrests; 10.6% following bystander-witnessed VF/VT arrests and 33% for paramedic-witnessed cardiac arrests. Logistic regression analysis showed an inverse association between ambulance response time interval and survival following all bystander-witnessed cardiac arrests (and VF/VT arrests). ONE YEAR SURVIVAL: 89% of bystander-witnessed cardiac arrest survivors and 92% of paramedic-witnessed cardiac arrests were still alive at 1 year post-arrest.

CONCLUSION

The trends in occurrence and survival following out-of-hospital cardiac arrest in Perth, WA, are similar to those found elsewhere. There is an opportunity to strengthen the chain of survival by reducing the response time interval and increasing the use of bystander cardiopulmonary resuscitation (CPR). First-responder programs and public access defibrillation will need to be considered in the light of local demographics, location and the epidemiologic features of out-of-hospital cardiac arrest.

Pulmonary capillary pressure measurement from pulmonary artery occlusion pressure decay profile analysis in sheep

Pulmonary capillary pressure (Ppc), the major factor responsible for pulmonary edema, cannot be directly measured in intact subjects but may be estimated by analysis of the pressure decay profile after pulmonary artery catheter balloon inflation. We compared three different methods of pulmonary artery occlusion pressure (Ppao) decay profile analysis to estimates of Ppc derived from lymph flow measurements in halothane-anesthesized sheep. The relationship between Ppc and lymph flow was first determined by increasing Ppc by left atrial balloon inflation, and was then used to determine Ppc during pulmonary hypertension produced by infusion of a thromboxane analog. All three methods of Ppao decay profile analysis demonstrated a correlation with Ppc estimated from lymph flow. However, the method using a single exponential analysis significantly overestimated Ppc, and none of the methods reliably estimated changes in the longitudinal distribution of pulmonary vascular resistance during pulmonary hypertension. These results suggest that Ppao decay profile analysis as currently performed has limited application.

Hemodynamic effects of diltiazem during vasoconstrictor pulmonary hypertension in sheep

Calcium channel blockers have been effective as pulmonary vasodilators in patients with pulmonary hypertension. The current study therefore compared the effects of prostaglandin E1, an effective pulmonary vasodilator, with the effects of the water-soluble calcium channel blocker diltiazem during pulmonary hypertension in sheep. Pulmonary hypertension was produced by continuous intravenous administration of U46619 to halothane-anesthetized sheep. Prostaglandin E1 decreased pulmonary artery pressure 29%, decreased pulmonary vascular resistance (Rp) 57%, and did not affect the ratio of pulmonary to systemic vascular resistance (Rp/Rs). Diltiazem decreased pulmonary artery pressure 15%, decreased Rp 50%, and did not affect Rp/Rs. When 0.33 mL/kg polyethylene glycol-ethanol vehicle (the vehicle used for nifedipine administration in a prior study) was administered during diltiazem infusion, pulmonary artery pressure increased 19%, Rp increased 72%, and Rp/Rs increased 29%. These results indicate that diltiazem is an effective pulmonary vasodilator and suggest that the previously reported unfavorable results of nifedipine may have been due to the vehicle used for nifedipine administration.

A new vascular clamp

A new vascular clamp called the occluder pad is described. It has significant utility when used in a variety of anatomic sites in either normal or diseased vessels. It possesses suitable tractive and occlusive forces while minimizing the mechanical forces applied to the vessel walls.

Shear force in angioplasty: its relation to catheter design and function

The inability to successfully position angioplasty catheters and the occurrence of complications during angioplasty procedures can, in part, be related to the shear forces generated during catheter introduction. Shear forces are the axial contact forces that the catheter system exerts on the inner arterial surfaces during advancement. The shear forces exerted by three different catheter designs (coaxial dilator, coaxial balloon, and linear extrusion) were measured in normal and atherosclerotic arteries; in modeled stenoses of variable severity, length, and compliance; and in modeled vessel angulations. The results with modeled vessels show that the linear extrusion catheter reduces the level of shear forces, particularly in narrow, long, noncompliant stenoses and in tortuous vessels. The stenotic artery results also show that the linear extrusion catheter minimizes these forces in tight lesions. The relative differences in forces are explained by the mechanism of action for each catheter. The reported occurrences of technical difficulties, complications, and long-term patency rates are then interpreted on the basis of the relative differences in measured shear forces. The results of this study combined with preliminary clinical data indicate that linear extrusion should facilitate placement and reduce associated complications.

Transluminal angioplasty: a mechanical-pathophysiological correlation of its physical mechanisms

We quantitatively determined the relative contribution of various factors leading to arterial lumen enlargement during transluminal angioplasty. Mechanical tests were conducted on both normal and atherosclerotic artery necropsy specimens. In our range of dilating pressures (0-3.4 atm or 0-50 lb/in2), content extrusion of fluid from the plaque accounted for 6-12% of the overall lumen area increase, while compaction of the plaque accounted for only 1-1.5%. The majority of the increase, 86.8-93%, was due to plaque and arterial wall disruption. The mechanism of disruption began with shearing of the plaque from the underlying artery at relatively low dilating pressures and continued with longitudinal tearing and stretching of the arterial wall at higher pressures. Diseased arteries dilated significantly more than nondiseased arteries at dilating pressures greater than or equal to 1.36 atm or 20 lb/in2 (P less than .05). In the range of stenoses that were tested (10-50%), the mean dilating pressure required to increase the lumen cross-sectional area by 50% was approximately 1.5 atm or 22 lb/in2.

Current status of dilatation catheters and guiding systems

New transluminal angioplasty catheters based upon the linear extrusion of the dilating element have been developed to facilitate placement of the dilating balloon within the arterial narrowing. In a multicenter study, the use of linear extrusion catheters has been shown to be safe and effective in adjunctive intraoperative peripheral dilatations. Physical measurements of the frictional forces exerted on the inner arterial surfaces during advancement of 3 angioplasty catheter designs show that the linear extrusion catheter consistently minimizes these forces. The use of a secondary guiding sheath in conjunction with a linear extrusion catheter provides additional directional capability. A secondary guiding sheath with a side port has recently been developed that allows access to difficult-to-cannulate vessels. The favorable results of the clinical studies and research data justify an ongoing evaluation of these concepts in percutaneous dilatation procedures and in intraoperative coronary procedures.

Coaxial balloon dilation and calibration of urethral strictures

New coaxial balloon dilators with standard urologic tip configurations have been designed for use in urethral strictures. Balloon dilatation provides several advantages over conventional dilatation of strictures including improved access and decreased mucosal trauma due to a low silhouette, adjustability of diameter and rigidity, decreased instrumentation, and facilitation of intermittent self-dilation by the patient. The instruments were evaluated in 51 strictures (41 patients) as both a dilator and a calibrator. All catheters were located across the stricture easily (although two required filiform attachments). All clinical goals were achieved, and no complications were identified. Two patients were started on a program of intermittent self-dilation after internal urethrotomy with good results. It is our initial clinical impression that slow, gradual dilation of strictures is superior to rapid, abrupt dilation. This can only be practically achieved with balloon dilators.