Revised resuscitation guidelines: Adrenaline versus adrenaline/vasopressin in a pig model of cardiopulmonary resuscitation—A randomised, controlled trial

Ultra-low tidal volume ventilation during cardiopulmonary resuscitation shows no mitigating effect on pulmonary end-organ damage compared to standard ventilation: insights from a porcine model

OBJECTIVE

This study aimed to determine whether ultra-low tidal volume ventilation (ULTVV) applied during cardiopulmonary resuscitation (CPR) compared with standard ventilation (intermittent positive pressure ventilation, IPPV) can reduce pulmonary end-organ damage in the post-resuscitation period.

METHODS

A prospective, randomized trial was conducted using a porcine model (n = 45). The animals were divided into three groups: IPPV, ULTVV, and a sham control group. Juvenile male pigs underwent CPR after inducing ventricular fibrillation and received the designated ventilation intervention [IPPV: tidal volume 6-8 ml per kilogram body weight (ml/kg BW), respiratory rate 10/min, FiO2 1.0; ULTVV: tidal volume 2-3 ml/kg BW, respiratory rate 50/min, FiO2 1.0]. A 20-h observation period followed if return of spontaneous circulation was achieved. Histopathological examination using the diffuse alveolar damage scoring system was performed on postmortem lung tissue samples. Arterial and venous blood gas analyses and ventilation/perfusion measurements via multiple inert gas elimination technique (MIGET) were repeatedly recorded during the experiment.

RESULTS

Out of the 45 experiments conducted, 28 animals were excluded based on predefined criteria. Histopathological analysis showed no significant differences in lung damage between the ULTVV and IPPV groups. ULTVV demonstrated adequate oxygenation and decarboxylation. MIGET measurements during and after resuscitation revealed no significant differences between the intervention groups.

CONCLUSION

In the short-term follow-up phase, ULTVV demonstrated similar histopathological changes and functional pulmonary parameters compared to standard ventilation. Further research is needed to investigate the long-term effects and clinical implications of ULTVV in resuscitation settings.

The Influence of Ultra-Low Tidal Volume Ventilation during Cardiopulmonary Resuscitation on Renal and Hepatic End-Organ Damage in a Porcine Model

The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) has eluded scientists for years. This porcine study aims to validate the hypothesis that ultra-low tidal volume ventilation (tidal volume 2–3 mL kg−1; ULTVV) minimizes renal and hepatic end-organ damage when compared to standard intermittent positive pressure ventilation (tidal volume 8–10 mL kg−1; IPPV) during CPR. After induced ventricular fibrillation, the animals were ventilated using an established CPR protocol. Upon return of spontaneous circulation (ROSC), the follow-up was 20 h. After sacrifice, kidney and liver samples were harvested and analyzed histopathologically using an Endothelial, Glomerular, Tubular, and Interstitial (EGTI) scoring system for the kidney and a newly developed scoring system for the liver. Of 69 animals, 5 in the IPPV group and 6 in the ULTVV group achieved sustained ROSC and were enlisted, while 4 served as the sham group. Creatinine clearance was significantly lower in the IPPV-group than in the sham group (p < 0.001). The total EGTI score was significantly higher for ULTVV than for the sham group (p = 0.038). Aminotransferase levels and liver score showed no significant difference between the intervention groups. ULTVV may be advantageous when compared to standard ventilation during CPR in the short-term ROSC follow-up period.

Bi-Level ventilation decreases pulmonary shunt and modulates neuroinflammation in a cardiopulmonary resuscitation model

Background

Optimal ventilation strategies during cardiopulmonary resuscitation are still heavily debated and poorly understood. So far, no convincing evidence could be presented in favour of outcome relevance and necessity of specific ventilation patterns. In recent years, alternative models to the guideline-based intermittent positive pressure ventilation (IPPV) have been proposed. In this randomized controlled trial, we evaluated a bi-level ventilation approach in a porcine model to assess possible physiological advantages for the pulmonary system as well as resulting changes in neuroinflammation compared to standard measures.

Methods

Sixteen male German landrace pigs were anesthetized and instrumented with arterial and venous catheters. Ventricular fibrillation was induced and the animals were left untreated and without ventilation for 4 minutes. After randomization, the animals were assigned to either the guideline-based group (IPPV, tidal volume 8–10 ml/kg, respiratory rate 10/min, F_iO₂1.0) or the bi-level group (inspiratory pressure levels 15–17 cmH₂O/5cmH₂O, respiratory rate 10/min, F_iO₂1.0). Mechanical chest compressions and interventional ventilation were initiated and after 5 minutes, blood samples, including ventilation/perfusion measurements via multiple inert gas elimination technique, were taken. After 8 minutes, advanced life support including adrenaline administration and defibrillations were started for up to 4 cycles. Animals achieving ROSC were monitored for 6 hours and lungs and brain tissue were harvested for further analyses.

Results

Five of the IPPV and four of the bi-level animals achieved ROSC. While there were no significant differences in gas exchange or hemodynamic values, bi-level treated animals showed less pulmonary shunt directly after ROSC and a tendency to lower inspiratory pressures during CPR. Additionally, cytokine expression of tumour necrosis factor alpha was significantly reduced in hippocampal tissue compared to IPPV animals.

Conclusion

Bi-level ventilation with a constant positive end expiratory pressure and pressure-controlled ventilation is not inferior in terms of oxygenation and decarboxylation when compared to guideline-based IPPV ventilation. Additionally, bi-level ventilation showed signs for a potentially ameliorated neurological outcome as well as less pulmonary shunt following experimental resuscitation. Given the restrictions of the animal model, these advantages should be further examined.

Ultra-low tidal volume ventilation-A novel and effective ventilation strategy during experimental cardiopulmonary resuscitation

BACKGROUND

The effects of different ventilation strategies during CPR on patient outcomes and lung physiology are still poorly understood. This study compares positive pressure ventilation (IPPV) to passive oxygenation (CPAP) and a novel ultra-low tidal volume ventilation (ULTVV) regimen in an experimental ventricular fibrillation animal model.

STUDY DESIGN

Prospective randomized controlled trial.

ANIMALS

30 male German landrace pigs (16-20 weeks).

METHODS

Ventricular fibrillation was induced in anesthetized and instrumented pigs and the animals were randomized into three groups. Mechanical CPR was initiated and ventilation was either provided by means of standard IPPV (RR: 10/min, Vt: 8-9 ml/kg, FiO2: 1,0, PEEP: 5 mbar), CPAP (O2-Flow: 10 l/min, PEEP: 5 mbar) or ULTVV (RR: 50/min, Vt: 2-3 ml/kg, FiO2: 1,0, PEEP: 5 mbar). Guideline-based advanced life support was applied for a maximum of 4 cycles and animals achieving ROSC were monitored for 6 h before terminating the experiment. Ventilation/perfusion ratios were performed via multiple inert gas elimination, blood gas analyses were taken hourly and extended cardiovascular measurements were collected constantly. Brain and lung tissue samples were taken and analysed for proinflammatory cytokine expression.

RESULTS

ULTVV provided sufficient oxygenation and ventilation during CPR while demanding significantly lower respiratory and intrathoracic pressures. V/Q mismatch was significantly decreased and lung injury was mitigated in surviving animals compared to IPPV and CPAP. Additionally, cerebral cytokine expression was dramatically reduced.

CONCLUSION

Ultra-low-volume ventilation during CPR in a porcine model is feasible and may provide lung-protective benefits as well as neurological outcome improvement due to lower inflammation. Our results warrant further studies and might eventually lead to new therapeutic options in the resuscitation setting.

Effect of hypertransfusion on the gastrointestinal tract after cardiac arrest in a porcine model

BACKGROUND

This study aimed to determine the potential protective effect of inducing hypertransfusion to the gastrointestinal tract following a porcine model of cardiac arrest and cardiopulmonary resuscitation (CPR) by evaluating the influence of gastrointestinal ultrastructure, ATPase and serum diamine oxidase.

METHODS

Ventricular fibrillation was induced by programmed electrical stimulation in 16 male domestic pigs (n=8/group). Four minutes after ventricular fibrillation, CPR was performed. The pigs that successfully restored spontaneous circulation received intravenous infusion of either norepinephrine to maintain the mean arterial pressure at 130% of the baseline before ventricular fibrillation or normal saline. Serum diamine oxidase and gastrointestinal ATPase activity were determined, and histopathological examination of the gastrointestinal tract was performed by light and electron microscopy.

RESULTS

CPR caused significant injury to the gastrointestinal tract, elevating serum diamine oxidase and causing destruction of intestinal microvillus in control animals. Na(+)-K(+) ATPase and Ca(2+) ATPase activity in gastric tissue were significantly elevated in animals receiving hypertransfusion treatment compared with the control animals. Hypertransfusion also significantly reduced serum diamine oxidase to below control levels after CPR. Moreover, severe injury sustained by the gastrointestinal tissue was markedly ameliorated under hypertransfusion conditions compared with the control animals.

CONCLUSIONS

Gastrointestinal injury and abnormal energy metabolism were strikingly evident following CPR. Hypertransfusion inducing hypertension can improve energy metabolism and ameliorate gastrointestinal mucosal injury, indicating that hypothermia significantly ameliorates gastrointestinal injury sustained following cardiac arrest.

Adrenaline, terlipressin, and corticoids versus adrenaline in the treatment of experimental pediatric asphyxial cardiac arrest

OBJECTIVE

To analyze if treatment with adrenaline (epinephrine) plus terlipressin plus corticoids achieves higher return of spontaneous circulation than adrenaline in an experimental infant animal model of asphyxial cardiac arrest.

DESIGN

Prospective randomized animal study.

SETTING

Experimental department in a University Hospital.

SUBJECTS

Forty-nine piglets were studied.

INTERVENTIONS

Cardiac arrest was induced by at least 10 minutes of removal of mechanical ventilation and was followed by manual external chest compressions and mechanical ventilation. After 3 minutes of resuscitation, piglets that did not achieve return of spontaneous circulation were randomized to two groups: adrenaline 0.02 mg kg every 3 minutes (20 animals) and adrenaline 0.02 mg kg every 3 minutes plus terlipressin 20 μg kg every 6 minutes plus hydrocortisone 30 mg kg one dose (22 animals). Resuscitation was discontinued when return of spontaneous circulation was achieved or after 24 minutes.

MEASUREMENT AND MAIN RESULTS

Return of spontaneous circulation was achieved in 14 piglets (28.5%), 14.2% with only cardiac massage and ventilation. Return of spontaneous circulation was achieved in 25% of piglets treated with adrenaline and in 9.1% of those treated with adrenaline plus terlipressin plus hydrocortisone (p = 0.167). Return of spontaneous circulation was achieved in 45.4% of animals with pulseless electric activity, 20% with asystole, and 0% with ventricular fibrillation (p = 0.037). Shorter duration of cardiac arrest, higher mean blood pressure and EtCO2 and lower PaCO2 before resuscitation, and higher mean blood pressure during resuscitation were associated with higher return of spontaneous circulation.

CONCLUSIONS

Treatment with adrenaline plus terlipressin plus corticoids does not achieve higher return of spontaneous circulation than that with adrenaline in an infant animal model of asphyxial cardiac arrest.

Novelties in pharmacological management of cardiopulmonary resuscitation

PURPOSE OF REVIEW

The ultimate goal of cardiopulmonary resuscitation is long-term neurologically intact survival. Despite numerous well-designed studies, the medications currently used in advanced cardiac life support have not demonstrated success in this regard. This review describes the novel therapeutics under investigation to improve functional recovery and survival.

RECENT FINDINGS

Whereas current medications focus on achieving return of spontaneous circulation and improved hemodynamics, novel therapies currently in development are focused on improving cellular survival and function by preventing metabolic derangement, protecting mitochondria, and preventing cell death caused by cardiac arrest. Improved cardiac and neurologic function and survival benefits have been observed using animal models of cardiopulmonary arrest.

SUMMARY

Although substantial data have shown benefits using robust animal models, further human studies are necessary to investigate the potential long-term benefits of these therapies.

Efficacy of vasopressin during cardio-pulmonary resuscitation in adult patients: a meta-analysis

BACKGROUND

Experimental and animal studies suggested that vasopressin may have a favorable survival profile during CPR. This meta-analysis aimed to determine the efficacy of vasopressin in adult cardiac patients.

METHODOLOGY

Meta-analysis of randomized control trials (RCTs) comparing the efficacy of vasopressin containing regimen during CPR in adult cardiac arrest population with an epinephrine only regimen.

RESULTS

A total of 6120 patients from 10 RCTs were included in this meta-analysis. Vasopressin use during CPR has no beneficial impact in an unselected population in ROSC [OR 1.19, 95% CI 0.93, 1.52], survival to hospital discharge [OR 1.13, 95% CI 0.89, 1.43], survival to hospital admission [OR 1.12, 95% CI 0.99, 1.27] and favorable neurological outcome [OR 1.02, 95% CI 0.75, 1.38]. ROSC in "in-hospital" cardiac arrest setting [OR 2.20, 95% CI 1.08, 4.47] is higher patients receiving vasopressin. Subgroup analyses revealed equal or higher chance of ROSC [OR 2.15, 95% CI 1.00, 4.61], higher possibility of survival to hospital discharge [OR 2.39, 95% CI 1.34, 4.27] and favorable neurological outcome [OR 2.58, 95% CI 1.39, 4.79] when vasopressin was used as repeated boluses of 4-5 times titrating desired effects during CPR.

CONCLUSION

ROSC in "in-hospital" cardiac arrest patients is significantly better when vasopressin was used. A subgroup analysis of this meta-analysis found that ROSC, survival to hospital admission and discharge and favorable neurological outcome may be better when vasopressin was used as repeated boluses of 4-5 times titrated to desired effects; however, overall no beneficial effect was noted in unselected cardiac arrest population.

Beneficial effects of terlipressin in pediatric cardiac arrest

OBJECTIVE

: Vasopressin and its analog, terlipressin (TP), are potent vasopressors that may be useful therapeutic agents in the treatment of cardiac arrest (CA), septic and catecholamine-resistant shock, and esophageal variceal hemorrhage. The American Heart Association 2000 guidelines recommend its use for adult ventricular fibrillation arrest, and the American Heart Association 2005 guidelines note that it may replace the first or second epinephrine dose. There is little reported experience with TP in cardiopulmonary resuscitation (CPR) of children. The purpose of this retrospective case series was to report successful return of spontaneous circulation after the rescue administration of vasopressin after prolonged CA and failure of conventional CPR, advanced life support, and epinephrine therapy in children.

METHODS

: Nine pediatric patients with asystole, aged 11 months to 14 years, who experienced 12 episodes of refractory CA and did not respond to conventional therapy. Terlipressin was administered as intravenous bolus doses of 20 mcg/kg to standard cardiopulmonary resuscitation.

RESULTS

: Return of spontaneous circulation was monitored and achieved in 6 of the 12 episodes. The mean duration of CPR was 24.8 minutes in these 12 episodes of CA with TP administration, with a range of 10 to 50 minutes (median, 23 minutes). Five survivors were discharged home without sequelae and with good neurologic status (score 1 by the pediatric cerebral performance category).

CONCLUSIONS

: The combination of TP to epinephrine during CPR may have a beneficial effect in children with CA. However, the recommendations for its use in the pediatric literature are based on limited clinical data.

Epinephrine in resuscitation: curse or cure?

The use of epinephrine during cardiac arrest has been advocated for decades and forms an integral part of the published guidelines. Its efficacy is supported by animal data, but human trial evidence is lacking. This is partly attributable to disparities in trial methodology. Epinephrine’s pharmacologic and physiologic effects include an increase in coronary perfusion pressure that is key to successful resuscitation. One possible explanation for the lack of epinephrine’s demonstrated efficacy in human trials of out-of-hospital cardiac arrest is the delay in its administration. A potential solution may be intraosseus epinephrine, which can be administered quicker. More importantly, it is the quality of the basic life support, early and uninterrupted chest compressions, early defibrillation and postresuscitation care that will provide the best chance of neurologically intact survival.

Terlipressin versus adrenaline in an infant animal model of asphyxial cardiac arrest

PURPOSE

The objective of this study was to compare the efficacy of terlipressin versus adrenaline in an experimental infant animal model of asphyxial cardiac arrest (ACA).

DESIGN

Prospective randomised animal study.

SETTING

Laboratory research department of a university hospital.

METHODS

Seventy-one, 2-month-old, mechanically ventilated piglets were investigated. ACA was induced by removal of mechanical ventilation. Resuscitation was performed by means of manual external chest compressions and mechanical ventilation (CC + V). After 3 min of CC + V, return of spontaneous circulation (ROSC) was observed in 11 animals. The 60 piglets without ROSC were then randomised to the four study groups: adrenaline standard dose (Asd): 0.01 mg/kg/3 min; adrenaline high dose (Ahd): first dose (0.01 mg/kg) and subsequent doses (0.1 mg/kg/3 min); terlipressin (T): 20 microg/kg/6 min; and adrenaline standard dose plus terlipressin (Asd + T).

MEASUREMENTS AND RESULTS

The relationship between haemodynamic (heart rate, blood pressure, ECG rhythm, cardiac index), respiratory (end-tidal CO(2), blood gas analysis) and tissue perfusion (gastric intramucosal pH, central, cerebral and renal saturation) parameters and ROSC was analysed. ROSC was achieved in three piglets treated with Asd (20%), four treated with Ahd (26.7%), one treated with T (6.7%) and seven treated with Asd + T (46.7%) (P = 0.099). ROSC was achieved in 43.1% of animals with pulseless electrical activity, 30.4% with asystole and none with ventricular fibrillation (P = 0.0001).

CONCLUSION

In this infant animal model of cardiac arrest, there was a non-significant trend towards better outcome when terlipressin was combined with adrenaline compared with the use of adrenaline or terlipressin alone.

Pediatric cardiac arrest refractory to advanced life support: is there a role for terlipressin?

OBJECTIVE

Pediatric cardiac arrest unresponsive to advanced life support and several adrenaline doses has a very poor prognosis. Alternative vasopressors could improve the results of resuscitation in such cases. We report our experience with the compassionate administration of terlipressin in children who suffered in-pediatric intensive care unit cardiac arrest and did not respond to immediate advanced life support and at least three epinephrine doses.

DESIGN

Prospective multicenter registry.

SETTING

Three pediatric intensive care units at university-affiliated tertiary care children's hospitals.

PATIENTS

Five pediatric patients, aged 5 mos to 12 yrs, with in-pediatric intensive care unit cardiac arrest unresponsive to advanced life support that included at least three epinephrine doses.

INTERVENTIONS

Addition of terlipressin (10-20 microg/kg intravenous, up to two doses) to standard cardiopulmonary resuscitation.

MEASUREMENTS AND MAIN RESULTS

Sustained return of spontaneous circulation was achieved in four cases, two of them were declared dead 6 and 12 hrs later, and the remaining two survived without cardiopulmonary procedures-related sequelae and with good neurologic condition.

CONCLUSIONS

Terlipressin might contribute to obtain sustained return of spontaneous circulation in children with refractory in-hospital cardiac arrest. A randomized controlled clinical trial should be conducted to investigate the optimal drug treatment in pediatric cardiac arrest.

Effects of stomach inflation on haemodynamic and pulmonary function during cardiopulmonary resuscitation in pigs

AIM

Stomach inflation during cardiopulmonary resuscitation (CPR) is frequent, but the effect on haemodynamic and pulmonary function is unclear. The purpose of this study was to evaluate the effect of clinically realistic stomach inflation on haemodynamic and pulmonary function during CPR in a porcine model.

METHODS

After baseline measurements ventricular fibrillation was induced in 21 pigs, and the stomach was inflated with 0L (n=7), 5L (n=7) or 10L air (n=7) before initiating CPR.

RESULTS

During CPR, 0, 5, and 10L stomach inflation resulted in higher mean pulmonary artery pressure [median (min-max)] [35 (28-40), 47 (25-50), and 51 (49-75) mmHg; P<0.05], but comparable coronary perfusion pressure [10 (2-20), 8 (4-35) and 5 (2-13) mmHg; P=0.54]. Increasing (0, 5, and 10L) stomach inflation decreased static pulmonary compliance [52 (38-98), 19 (8-32), and 12 (7-15) mL/cmH(2)O; P<0.05], and increased peak airway pressure [33 (27-36), 53 (45-104), and 103 (96-110) cmH(2)O; P<0.05). Arterial oxygen partial pressure was higher with 0L when compared with 5 and 10L stomach inflation [378 (88-440), 58 (47-113), and 54 (43-126) mmHg; P<0.05). Arterial carbon dioxide partial pressure was lower with 0L when compared with 5 and 10L stomach inflation [30 (24-36), 41(34-51), and 56 (45-68) mmHg; P<0.05]. Return of spontaneous circulation was comparable between groups (5/7 in 0L, 4/7 in 5L, and 3/7 in 10L stomach inflation; P=0.56).

CONCLUSIONS

Increasing levels of stomach inflation had adverse effects on haemodynamic and pulmonary function, indicating an acute abdominal compartment syndrome in this CPR model.