Inhaled nitric oxide reduces pulmonary vascular resistance more than prostaglandin E(1) during heart transplantation

Inhaled nitric oxide and postoperative outcomes in cardiac surgery with cardiopulmonary bypass: A systematic review and meta-analysis

Cardiac surgeries under cardiopulmonary bypass (CPB) are complex procedures with high incidence of complications, morbidity and mortality. The inhaled nitric oxide (iNO) has been frequently used as an important composite of perioperative management during cardiac surgery under CPB. We conducted a meta-analysis of published randomized clinical trials (RCTs) to assess the effects of iNO on reducing postoperative complications, including the duration of postoperative mechanical ventilation, length of intensive care unit (ICU) stay, length of hospital stay, mortality, hemodynamic improvement (the composite right ventricular failure, low cardiac output syndrome, pulmonary arterial pressure, and vasoactive inotropic score) and myocardial injury biomarker (postoperative troponin I levels). Subgroup analyses were performed to assess the effect of modification and interaction. These included iNO dosage, the timing and duration of iNO therapy, different populations (children and adults), and comparators (other vasodilators and placebo or standard care). A comprehensive search for iNO and cardiac surgery was performed on online databases. Twenty-seven studies were included after removing the duplicates and irrelevant articles. The results suggested that iNO could reduce the duration of mechanical ventilation, but had no significance in the ICU stay, hospital stay, and mortality. This may be attributed to the small sample size of the most included studies and heterogeneity in timing, dosage and duration of iNO administration. Well-designed, large-scale, multicenter clinical trials are needed to further explore the effect of iNO in improving postoperative prognosis in cardiovascular surgical patients.

The beneficial use of nitric oxide during cardiopulmonary bypass on postoperative outcomes in children and adult patients: a systematic review and meta-analysis of 2897 patients

PURPOSE

Investigate inhaled nitric oxide's influence on mortality rates, mechanical ventilation and cardiopulmonary bypass duration, and length of stay in the intensive care unit and hospital when administered during cardiopulmonary bypass.

METHODS

Following the PRISMA guidelines, we searched four electronic databases (PubMed, EMBASE, Cochrane Library, and Web of Science) up to 4th March 2023. The protocol was registered in the PROSPERO database with ID: CRD42023423007. Using Review Manager software, we reported outcomes as risk ratios (RRs) or mean difference (MD) and confidence intervals (CIs).

RESULTS

The meta-analysis included a total of 17 studies with 2897 patients. Overall, there were no significant differences in using nitric oxide over control concerning mortality (RR = 1.03, 95% CI 0.73 to 1.45; P = 0.88) or cardiopulmonary bypass duration (MD = -0.14, 95% CI - 0.96 to 0.69; P = 0.74). The intensive care unit days were significantly lower in the nitric oxide group than control (MD = -0.80, 95% CI - 1.31 to -0.29; P = 0.002). Difference results were obtained in terms of the length of stay in the hospital according to sensitivity analysis (without sensitivity [MD = -0.41, 95% CI - 0.79 to -0.02; P = 0.04] vs. with sensitivity [MD = -0.31, 95% CI - 0.69 to 0.07; P = 0.11]. Subgroup analysis shows that, in children, nitric oxide was favored over control in significantly reducing the duration of mechanical ventilation (MD = -4.58, 95% CI - 5.63 to -3.53; P < 0.001).

CONCLUSION

Using inhaled nitric oxide during cardiopulmonary bypass reduces the length of stay in the intensive care unit, and for children, it reduces the duration of mechanical ventilation.

Review of Postoperative Care for Heart Transplant Recipients

The early postoperative management strategies after heart transplantation include optimizing the function of the denervated heart, correcting the causes of hemodynamic instability, and initiating and maintaining immunosuppressive therapy, allograft rejection surveillance, and prophylaxis against infections caused by immunosuppression. The course of postoperative support is influenced by the quality of allograft myocardial protection prior to implantation and reperfusion, donor-recipient heart size matching, surgical technique of orthotopic heart transplantation, and patient factors (eg, preoperative condition, immunologic compatibility, postoperative vasomotor tone, severity and reversibility of pulmonary vascular hypertension, pulmonary function, mediastinal blood loss, and end-organ perfusion). This review provides an overview of the early postoperative care of recipients and includes a brief description of the surgical techniques for orthotopic heart transplantation.

Balancing the tug of war: intraoperative and postoperative management of multiorgan transplantation

PURPOSE OF REVIEW

Multiorgan heart transplants (MOHT) have steadily increased and account for approximately 4% of all heart transplants performed. Although long-term outcomes of MOHT are similar to heart transplant alone, perioperative management remains an issue with nearly double the rate of prolonged hospitalization. Better understanding of hemodynamic environments encountered and appropriate therapeutic targets can help improve perioperative management.

RECENT FINDINGS

Accurate and precise hemodynamic monitoring allows for early identification of complications and prompt assessment of therapeutic interventions. This can be achieved with a multimodal approach using traditional monitoring tools, such a pulmonary artery catheter and arterial line in conjunction with transesophageal echocardiography. Specific targets for optimizing graft perfusion are determined by phase of surgery and organ combination. In some circumstances, the surgical sequence of transplant can help mitigate or avoid certain detrimental hemodynamic environments.

SUMMARY

With better understanding of the array of hemodynamic environments that can develop during MOHT, we can work to standardize hemodynamic targets and therapeutic interventions to optimize graft perfusion. Effectively navigating this perioperative course with multimodal monitoring including transesophageal echocardiography can mitigate impact of complications and reduce prolonged hospitalization associated with MOHT.

Effect of nitric oxide on postoperative acute kidney injury in patients who underwent cardiopulmonary bypass: a systematic review and meta-analysis with trial sequential analysis

BACKGROUND

The effect of nitric oxide (NO) on renal function is controversial in critical illness. We performed a systematic meta-analysis and trial sequential analysis to determine the effect of NO gas on renal function and other clinical outcomes in patients requiring cardiopulmonary bypass (CPB). The primary outcome was the relative risk (RR) of acute kidney injury (AKI), irrespective of the AKI stage. The secondary outcome was the mean difference (MD) in the length of ICU and hospital stay, the RR of postoperative hemorrhage, and the MD in levels of methemoglobin. Trial sequential analysis (TSA) was performed for the primary outcome.

RESULTS

54 trials were assessed for eligibility and 5 studies (579 patients) were eligible for meta-analysis. NO was associated with reduced risk of AKI (RR 0.76, 95% confidential interval [CI], 0.62 to 0.93, I2 = 0%). In the subgroup analysis by NO initiation timing, NO did not decrease the risk of AKI when started at the end of CPB (RR 1.20, 95% CI 0.52-2.78, I2 = 0%). However, NO did significantly reduce the risk of AKI when started from the beginning of CPB (RR 0.71, 95% CI 0.54-0.94, I2 = 10%). We conducted TSA based on three trials (400 patients) using KDIGO criteria and with low risk of bias. TSA indicated a CI of 0.50-1.02 and an optimal information size of 589 patients, suggesting a lack of definitive conclusion. Furthermore, NO does not affect the length of ICU and hospital stay or the risk of postoperative hemorrhage. NO slightly increased the level of methemoglobin at the end of CPB (MD 0.52%, 95% CI 0.27-0.78%, I2 = 90%), but it was clinically negligible.

CONCLUSIONS

NO appeared to reduce the risk of postoperative AKI in patients undergoing CPB. Additional studies are required to ascertain the finding and further determine the dosage, timing and duration of NO administration.

Complications of Cardiac Transplantation

PURPOSE OF REVIEW

Despite the improvement in medical therapy for heart failure and the advancements in mechanical circulatory support, heart transplantation (HT) still remains the best therapeutic option to improve survival and quality of life in patients with advanced heart failure. Nevertheless, HT recipients are exposed to the risk of several potential complications that may impair their outcomes. In this article, we aim to provide a practical and scholarly framework for clinicians approaching heart transplant medicine, as well as a concise update for the experienced readers on the most relevant post-HT complications.

RECENT FINDINGS

While recognizing that most of the treatments herein discussed are based more on experience than on solid scientific evidence, significant step forward has been made in particular in the recognition and management of primary graft dysfunction, antibody-mediated rejection, and renal dysfunction. Complications after HT may vary according to the time from surgery and can be related to graft function and pathology or to diseases and dysfunctions occurring in other organs or systems, mainly as side effects of immunosuppressive drugs and progression of pre-existing conditions. Future research needs to focus on improving precision diagnostics of causes of graft dysfunction and on reaching an optimal and customized balance between efficacy and toxicities of immunosuppressive strategies.

Nitric Oxide in Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To investigate the efficacy and safety of perioperative administration of nitric oxide in cardiac surgery.

DESIGN

Meta-analysis of randomized controlled trials (RCTs).

PARTICIPANTS

Cardiac surgery patients.

INTERVENTIONS

A search of Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and MEDLINE for RCTs that compared nitric oxide with placebo or other comparators.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit (ICU) stay, and secondary outcomes were mortality, duration of mechanical ventilation, and reduction of mean pulmonary artery pressure. The study included 18 RCTs comprising 958 patients. The authors calculated the pooled odds ratio (OR) and the mean difference (MD) with random-effects model. Quantitative synthesis of data demonstrated a clinically negligible reduction in the length of ICU stay (MD -0.38 days, confidence interval CI [-0.65 to -0.11]; p = 0.005) and mechanical ventilation duration (MD -4.81 hours, CI [-7.79 to -1.83]; p = 0.002) compared with all control interventions with no benefit on mortality.

CONCLUSIONS

Perioperative delivery of inhaled nitric oxide resulted to be of no or minimal benefit in patients with pulmonary hypertension undergoing cardiac surgery. Large, randomized trials are needed to further assess its effect on major clinical outcomes and its cost-effectiveness.

Prostacyclins in Cardiac Surgery: Coming of Age

Prostacyclin (prostaglandin I2 [PGI2]) is an eicosanoid lipid mediator produced by the endothelial cells. It plays pivotal roles in vascular homeostasis by virtue of its potent vasodilatory and antithrombotic effects. Stable pharmacological analogues of PGI2 are used for treatment of pulmonary hypertension and right ventricular failure. PGI2 dose dependently inhibits platelet activation induced by adenosine-5′-diphosphate, arachidonic acid, collagen, and low-dose thrombin. This property has led to its use as an alternative to direct thrombin inhibitors in patients with type II heparin-induced thrombocytopenia (HIT) undergoing cardiac surgery. The aims of this review are the following: (1) to review the pharmacology of PGI2 and its derivatives, (2) to present the evidence for their use in pulmonary hypertension and right heart failure, and (3) to discuss their utility in the management of HIT in cardiac surgery.

Anesthetic management of the patient undergoing heart transplantation

Cardiac transplantation is the treatment of choice for patients with end-stage heart failure. Over the years, significant advances in patient selection, donor optimization and selection, and optimization of immunosuppression strategies have markedly improved outcomes. In this review, we highlight patient selection, donor management and procurement, heart transplantation procedure, and intraoperative and postoperative management of heart transplants.

Aerosolized Vasodilators for the Treatment of Pulmonary Hypertension in Cardiac Surgical Patients: A Systematic Review and Meta-analysis

BACKGROUND

In cardiac surgery, pulmonary hypertension is an important prognostic factor for which several treatments have been suggested over time. In this systematic review and meta-analysis, we compared the efficacy of inhaled aerosolized vasodilators to intravenously administered agents and to placebo in the treatment of pulmonary hypertension during cardiac surgery. We searched MEDLINE, CENTRAL, EMBASE, Web of Science, and clinicaltrials.gov databases from inception to October 2015. The incidence of mortality was assessed as the primary outcome. Secondary outcomes included length of stay in hospital and in the intensive care unit, and evaluation of the hemodynamic profile.

METHODS

Of the 2897 citations identified, 10 studies were included comprising a total of 434 patients.

RESULTS

Inhaled aerosolized agents were associated with a significant decrease in pulmonary vascular resistance (-41.36 dyne·s/cm, P= .03) and a significant increase in mean arterial pressure (8.24 mm Hg, P= .02) and right ventricular ejection fraction (7.29%, P< .0001) when compared to intravenously administered agents. No significant hemodynamically meaningful differences were observed between inhaled agents and placebo; however, an increase in length of stay in the intensive care unit was shown with the use of inhaled aerosolized agents (0.66 days, P= .01). No other differences were observed for either comparison.

CONCLUSIONS

The administration of inhaled aerosolized vasodilators for the treatment of pulmonary hypertension during cardiac surgery is associated with improved right ventricular performance when compared to intravenously administered agents. This review does not support any benefit compared to placebo on major outcomes. Further investigation is warranted in this area of research and should focus on clinically significant outcomes.

Postoperative management of heart transplantation patients

Heart transplant recipients are at risk for a number of post-transplantation complications such as graft dysfunction, rejection, and infection. The rates of many complications are decreasing over time, and prognosis is improving. However, these patients continue to experience significant morbidity and mortality. This review focuses on the optimal management of heart transplant recipients in the postoperative period, based on current knowledge. More information is needed about the best ways to predict, prevent, and treat primary graft dysfunction, right ventricular failure, and cellular and antibody-mediated rejection.

Management of Pulmonary Hypertension in the Operating Room

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.

Inhaled nitric oxide in cardiac surgery: Evidence or tradition?

Inhaled nitric oxide (iNO) therapy as a selective pulmonary vasodilator in cardiac surgery has been one of the most significant pharmacological advances in managing pulmonary hemodynamics and life threatening right ventricular dysfunction and failure. However, this remarkable story has experienced a roller-coaster ride with high hopes and nearly universal demonstration of physiological benefits but disappointing translation of these benefits to harder clinical outcomes. Most of our understanding on the iNO field in cardiac surgery stems from small observational or single centre randomised trials and even the very few multicentre trials fail to ascertain strong evidence base. As a consequence, there are only weak clinical practice guidelines on the field and only European expert opinion for the use of iNO in routine and more specialised cardiac surgery such as heart and lung transplantation and left ventricular assist device (LVAD) insertion. In this review the authors from a specialised cardiac centre in the UK with a very high volume of iNO usage provide detailed information on the early observations leading to the European expert recommendations and reflect on the nature and background of these recommendations. We also provide a summary of the progress in each of the cardiac subspecialties for the last decade and initial survey data on the views of senior anaesthetic and intensive care colleagues on these recommendations. We conclude that the combination of high price tag associated with iNO therapy and lack of substantial clinical evidence is not sustainable on the current field and we are risking loosing this promising therapy from our daily practice. Overcoming the status quo will not be easy as there is not much room for controlled trials in heart transplantation or in the current atmosphere of LVAD implantation. However, we call for international cooperation to conduct definite studies to determine the place of iNO therapy in lung transplantation and high risk mitral surgery. This will require new collaboration between the pharmaceutical companies, national grant agencies and the clinical community. Until these trials are realized we should gather multi-institutional experience from large retrospective studies and prospective data from a new international registry. We must step up international efforts if we wish to maintain the iNO modality in the armamentarium of hemodynamic tools for the perioperative management of our high risk cardiac surgical patients.

Role of nitric oxide in pathophysiology and treatment of pulmonary hypertension

Pulmonary hypertension is a condition characterized by vasoconstriction, vascular cell proliferation, inflammation, microthrombosis, and vessel wall remodelation. Pulmonary endothelial cells produce vasoactive substances with vasoconstrictive as well as vasodilatative effects. The imbalance of these endothelium-derived vasoactive substances induced by endothelial dysfunction is very important in the pathogenesis of PH. One of most important substances with vasodilatative effect is nitric oxide. We provide a comprehensive insight into role of NO in the pathgenesis of PH and discuss perspectives and challenges in PH therapy based on NO administration.

Pharmacologic management of perioperative pulmonary hypertension

Perioperative pulmonary hypertension can originate from an established disease or acutely develop within the surgical setting. Patients with increased pulmonary vascular resistance are consequently at greater risk for complications. Despite the various specific therapies available, the ideal therapeutic approach in this patient population is not currently clear. This article describes the basic principles of perioperative pulmonary hypertension and reviews the different classes of agents used to promote pulmonary vasodilation in the surgical setting.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Perioperative management in patients with pulmonary hypertension

Patients with pulmonary hypertension (PH) are being encountered more commonly in the perioperative period and this trend is likely to increase as improvements in the recognition, management, and treatment of the disease continue to occur. Management of these patients is challenging due to their tenuous hemodynamic status. Recent advances in the understanding of the patho-physiology, risk factors, monitoring, and treatment of the disease provide an opportunity to reduce the morbidity and mortality associated with PH in the peri-operative period. Management of these patients requires a multi-disciplinary approach and meticulous care that is best provided in centers with vast experience in PH.

In this review, we provide a detailed discussion about oerioperative strategies in PH patients, and give evidence-based recommendations, when applicable.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

Inhaled nitric oxide after left ventricular assist device implantation: a prospective, randomized, double-blind, multicenter, placebo-controlled trial

BACKGROUND

Used frequently for right ventricular dysfunction (RVD), the clinical benefit of inhaled nitric oxide (iNO) is still unclear. We conducted a randomized, double-blind, controlled trial to determine the effect of iNO on post-operative outcomes in the setting of left ventricular assist device (LVAD) placement.

METHODS

Included were 150 patients undergoing LVAD placement with pulmonary vascular resistance ≥ 200 dyne/sec/cm(-5). Patients received iNO (40 ppm) or placebo (an equivalent concentration of nitrogen) until 48 hours after separation from cardiopulmonary bypass, extubation, or upon meeting study-defined RVD. For ethical reasons, crossover to open-label iNO was allowed during the 48-hour treatment period if RVD criteria were met.

RESULTS

RVD criteria were met by 7 of 73 patients (9.6%; 95% confidence interval, 2.8-16.3) in the iNO group compared with 12 of 77 (15.6%; 95% confidence interval, 7.5-23.7) who received placebo (p = 0.330). Time on mechanical ventilation decreased in the iNO group (median days, 2.0 vs 3.0; p = 0.077), and fewer patients in the iNO group required an RVAD (5.6% vs 10%; p = 0.468); however, these trends did not meet statistical boundaries of significance. Hospital stay, intensive care unit stay, and 28-day mortality rates were similar between groups, as were adverse events. Thirty-five patients crossed over to open-label iNO (iNO, n = 15; placebo, n = 20). Eighteen patients (iNO, n = 9; placebo, n = 9) crossed over before RVD criteria were met.

CONCLUSIONS

Use of iNO at 40 ppm in the perioperative phase of LVAD implantation did not achieve significance for the primary end point of reduction in RVD. Similarly, secondary end points of time on mechanical ventilation, hospital or intensive care unit stay, and the need for RVAD support after LVAD placement were not significantly improved.

Immediate postoperative care of the heart transplant recipient: perils and triumphs

The early postoperative care of a heart transplant recipient remains challenging, even in experienced centers with a long tradition of excellence. Approximately 10% to 20% of heart transplant recipients experience potentially life-threatening right ventricular dysfunction intraoperatively and early postoperatively due to an elevated pulmonary vascular resistance. In addition, heart transplant recipients experience a high risk of perioperative hemorrhage, as well as opportunistic infection and rejection. The authors describe a case of severe right ventricular dysfunction in a 46-year-old male several hours after heart transplantation for a dilated cardiomyopathy. This patient was salvaged by judicious multimodality therapy including the use of adrenergic agents, phosphodiesterase inhibitors, inhaled nitric oxide, and extracorporeal membrane oxygenation. The risk factors for the development of early graft failure after heart transplantation are reviewed, along with the principles of appropriate management of this complication.

[Severe pulmonary hypertension: implications for anesthesia in laparoscopic surgery]

Pulmonary arterial hypertension (PAH), defined by a mean pulmonary arterial pressure greater than 25 mm Hg at rest or greater than 30 mm Hg with exercise, poses a challenge to anesthesiologists during perioperative management. The pathogenesis of PAH is multifactorial and includes genetic factors that explain individual susceptibility and external trigger or risk factors. We report the case of a woman with severe pulmonary hypertension who was waiting for a lung transplant when she was scheduled for laparoscopic cholecystectomy. We discuss the clinical course and monitoring of hemodynamic and respiratory parameters at the different stages of laparoscopic surgery.

Effect of prepro-calcitonin gene-related peptide-expressing endothelial progenitor cells on pulmonary hypertension

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a potent smooth muscle cell proliferation inhibitor and vasodilator. It is now believed that CGRP plays an important role in maintaining a low pulmonary vascular resistance. We evaluated the therapeutic effect of intravenously administered CGRP-expressing endothelial progenitor cells (EPCs) on left-to-right shunt-induced pulmonary hypertension in rats.

METHODS

Endothelial progenitor cells were obtained from cultured human peripheral blood mononuclear cells. The genetic sequence for CGRP was subcloned into cultured EPCs by human expression plasmid. Pulmonary hypertension was established in immunodeficient rats with an abdominal aorta to inferior vena cava shunt operation. The transfected EPCs were injected through the left jugular vein at 10 weeks after the shunt operation. Mean pulmonary artery pressure and total pulmonary vascular resistance were detected with right cardiac catheterization at 4 weeks. The distribution of EPCs in the lung tissue was examined with immunofluorescence technique. Histopathologic changes in the structure of the pulmonary arteries was observed with electron microscopy and subjected to computerized image analysis.

RESULTS

The lungs of rats transplanted with CGRP-expressing EPCs demonstrated a decrease in both mean pulmonary artery pressure (17.64 +/- 0.79 versus 22.08 +/- 0.95 mm Hg; p = 0.018) and total pulmonary vascular resistance (1.26 +/- 0.07 versus 2.45 +/- 0.18 mm Hg x min/mL; p = 0.037) at 4 weeks. Immunofluorescence revealed that intravenously administered cells were incorporated into the pulmonary vasculature. Pulmonary vascular remodeling was remarkably attenuated with the administration of CGRP-expressing EPCs.

CONCLUSIONS

The transplantation of CGRP-expressing EPCs may effectively attenuate established pulmonary hypertension and exert reversal effects on pulmonary vascular remodeling. Our findings suggest that the therapy based on the combination of both CGRP transfection and EPCs may be a potentially useful strategy for the treatment of pulmonary hypertensive disorders.

Is a fall in baseline heart rate a reliable predictor of a successful single shot caudal epidural in children?

BACKGROUND

This study was designed to investigate whether a fall in heart rate (HR) with injection of local anesthetic into the caudal space can be used as a predictor of correct needle placement.

METHODS

Two hundred and twenty pediatric patients undergoing infraumbilical surgery were recruited to the study. After induction of general anesthesia, baseline HR was recorded and caudal block was performed using 0.75-1 ml x kg(-1) 0.25% bupivacaine, which was injected at a rate of 1 ml x 3 s(-1). The change in HR while injecting an initial 0.2 ml x kg(-1) of drug and during total drug injection was recorded. HR reduction of > or = 3 b x min(-1) was considered a positive test for correct needle placement. The success of block was judged by HR response to skin incision, endtidal halothane concentration required for maintenance of anesthesia and postoperative pain scores.

RESULTS

Caudal block was successful in 209/220 (95%) patients. Mean HR following the initial drug injection (111 +/- 17.7, P < 0.01) and entire drug injection (108.8 +/- 17.2, P < 0.01) was significantly lower than baseline (116.2 +/- 17.5). HR reduction of > or = 3 b x min(-1) was present in 190/209 and 199/209 successful block following initial drug injection and total drug injection respectively. The analysis of study data showed that a fall in HR is a predictor of successful caudal block, with a sensitivity of 90.9%, specificity of 100% and a positive predictive value of 100% after initial injection of local anesthetic.

CONCLUSIONS

We conclude that decrease in HR with drug injection is a simple, objective and reliable test to predict success of caudal block.

Treatment with phosphodiesterase inhibitors type III and V: milrinone and sildenafil is an effective combination during thromboxane-induced acute pulmonary hypertension

OBJECTIVES

To evaluate the effects of phosphodiesterase type III and V (PDEIII and PDEV) inhibition on pulmonary and systemic haemodynamics in a porcine model of acute pulmonary hypertension.

METHODS

Twenty-four adult swine were anaesthetized with 1 MAC isoflurane and mechanically ventilated with an FI(O(2)) of 100%. Micromanometer-tipped catheters were placed in the ascending aorta, pulmonary artery and right ventricle. Pulmonary flow was measured with a perivascular probe using transit time ultrasound. Pulmonary hypertension was induced with a continuous infusion of the thromboxane analogue, U46619. The animals were then randomized to four groups: Group 1 (n=6) received 50 mg of sildenafil (PDEV inhibitor) diluted in water via an orogastric tube; Group 2 (n=6) received 50 microg kg(-1) of i.v. milrinone (PDEIII inhibitor); Group 3 (n=6) received sildenafil followed by milrinone; and Group 4 (n=6) received placebo via an orogastric tube.

RESULTS

Pulmonary hypertension was achieved in all animals. Calculated pulmonary vascular resistance decreased by an average of 36% after sildenafil (P<0.05), 41% after milrinone (P<0.05), and 61% with both drugs combined (P<0.05). Systemic vascular resistance decreased by 37% (P<0.05) with milrinone alone, and 36% (P<0.05) with milrinone and sildenafil combined but it was preserved in the sildenafil group. Cardiac output and right ventricular dP/dT were significantly improved after milrinone or both drugs combined, but not with sildenafil.

CONCLUSION

Milrinone and sildenafil are effective pulmonary vasodilators, with independent action and additive effect. Both drugs combined achieved a better haemodynamic profile, with greater pulmonary vasodilatation and increased contractility but without additional systemic vasodilatation. The systemic haemodynamic profile (systemic vasodilation, cardiac output, right ventricular dP/dT) is improved with milrinone but not with sildenafil.

Effects of a new phosphodiesterase enzyme type V inhibitor (UK 343-664) versus milrinone in a porcine model of acute pulmonary hypertension

BACKGROUND

Perioperative pulmonary hypertension remains a clinical challenge. The phosphodiesterase enzyme type III inhibitor milrinone produces pulmonary vasodilation but lacks selectivity. Sildenafil, a phosphodiesterase enzyme type V inhibitor, can also induce relaxation of the pulmonary vasculature; however, only the oral formulation is presently available. This study evaluated the effects of a new intravenous sildenafil analogue--UK 343-664--compared with milrinone during acute pulmonary hypertension in a porcine model of thromboxane-induced pulmonary hypertension.

METHODS

After acute pulmonary hypertension, 24 adult swine were randomized to 3 groups. Group 1 (n = 9) received an intravenous dose of 500 microg of UK 343-664, group 2 (n = 8) received milrinone 50 mg/kg, and group 3 (n = 7) received 10 mL of normal saline solution. All agents were administered for more than 5 minutes. Data were recorded continuously for 30 minutes.

RESULTS

Both milrinone and UK 343-664 partially reversed thromboxane-induced pulmonary hypertension, with a notable decrease in mean pulmonary artery pressure and pulmonary vascular resistance and a concomitant increase in cardiac output. In addition, milrinone improved right ventricular contractility but produced marked systemic vasodilatation. In contrast, the administration of UK 343-664 was associated with pulmonary vasodilatation, without appreciable changes in systemic arterial pressure or vascular resistance.

CONCLUSIONS

Milrinone and UK 343-664 were equally effective as pulmonary vasodilators; however, only UK 343-664 exhibited a high degree of pulmonary selectivity. Potential uses for this new phosphodiesterase enzyme type V inhibitor warrant further study.

Inhaled nitric oxide therapy in adults: European expert recommendations

BACKGROUND

Inhaled nitric oxide (iNO) has been used for treatment of acute respiratory failure and pulmonary hypertension since 1991 in adult patients in the perioperative setting and in critical care.

METHODS

This contribution assesses evidence for the use of iNO in this population as presented to a expert group jointly organised by the European Society of Intensive Care Medicine and the European Association of Cardiothoracic Anaesthesiologists.

CONCLUSIONS

Expert recommendations on the use of iNO in adults were agreed on following presentation of the evidence at the expert meeting held in June 2004.

Severe right heart failure after heart transplantation. A single-center experience

We reviewed our heart transplantation recipient population, using hard criteria defining severe right heart failure (RHF), and analyzed possible risk factors for outcome after RHF. Between 1983 and 1998 621 cardiac transplantations were performed at our institution. RHF was defined by the necessity to implant an assist device or echocardiographically confirmed right ventricular ballooning with concomitant end organ failure. RHF patients were compared with a matched control group. Thirty-five patients (5.9%) with severe RHF after transplantation fulfilled inclusion criteria. Of these, 32 patients died, while none of the control patients died (P < 0.001). Increased preoperative pulmonary capillary wedge (P = 0.005) and mean pulmonary artery pressure (P = 0.006) were identified as significant risk factors for severe RHF. Severe RHF as defined in our study is irreversible in almost every case without differences among therapeutical concepts. Hence, improvement of postoperative outcome necessitates avoidance or aggressive therapy of possible risk factors.

Nebulized nitric oxide/nucleophile adduct reduces pulmonary vascular resistance in mechanically ventilated septicemic sheep*

OBJECTIVE

To study the effects of a novel, intermittently administered, aerosolized nitric oxide donor, methyl-N-2-dimethylaminoethyl-3-aminoproprionid/nitric oxide (DMDE-NO), on pulmonary hemodynamic responses to sepsis.

DESIGN

Prospective, randomized, controlled study in awake sheep.

SETTING

Investigational intensive care unit of a university medical center.

SUBJECTS

Thirteen instrumented merino ewes weighing 36 +/- 0.9 kg underwent a hemodynamic study 1 wk postoperatively.

INTERVENTIONS

On the day of the experiment, the sheep received a tracheotomy and mechanical ventilation was subsequently started. Pseudomonas aeruginosa bacteria were infused intravenously, beginning at time 0 hrs and continuing throughout the 48-hr experiment. The animals were randomly assigned to receive nebulized DMDE-NO 1 mg/kg, dissolved in 8 mL of saline (DMDE-NO group, n = 7), or nebulized saline alone (control group, n = 6) delivered by a nebulizer. The nebulizations started at 2, 6, 20, 24, and 43 hrs after the baseline, each time lasting for 1 hr.

MEASUREMENTS AND MAIN RESULTS

Inhaled aerosolized DMDE-NO reversibly reduced the sepsis-induced increase in pulmonary artery pressure by 13-17% and pulmonary vascular resistance index by 21-31% compared with the values registered before the administration of the drug. Systemic hemodynamics underwent an early hypodynamic phase followed by a gradual increase in cardiac index and a decrease in both mean arterial pressure and systemic vascular resistance index, but with no significant difference between groups. Gas exchange variables and plasma nitrite/nitrate did not differ significantly between groups either.

CONCLUSIONS

In sheep, inhaled nebulized DMDE-NO reduces sepsis-induced changes in pulmonary hemodynamics with no change in systemic hemodynamics or gas exchange.

Cardiac transplantation

Cardiac transplantation is a proven, accepted mode of therapy for selected patients with end-stage heart failure, but the inadequate number of suitable donor hearts available ultimately limits its application. This chapter reviews adult cardiac transplantation, with an emphasis on the anesthetic considerations of the heart transplant operation itself.

Extracorporeal Membrane Oxygenation is Superior to Right Ventricular Assist Device for Acute Right Ventricular Failure After Heart Transplantation

BACKGROUND

Acute right ventricular failure after heart transplantation is a life-threatening condition, and sometimes the use of mechanical circulatory support is inevitable. The aim of this retrospective study was to investigate the effectiveness of two different mechanical circulatory support systems for this indication.

METHODS

From 1984 to 2003, 28 heart transplant recipients exhibited right ventricular failure resistant to drug therapy. Right ventricular assist device (n = 15) or extracorporeal membrane oxygenation (n = 13) was implanted to support the failing heart.

RESULTS

Overall in-hospital survival was 43%. In the right ventricular assist device group, only 2 patients (13%) could be weaned from mechanical circulatory support compared with 10 patients (77%) in the extracorporeal membrane oxygenation group (p = 0.001). Retransplantation was necessary in 6 patients in the right ventricular assist device group and in 1 patient in the extracorporeal membrane oxygenation group (p = 0.049). There was no difference in patient survival between groups, but graft survival was significantly better in the extracorporeal membrane oxygenation group (p = 0.005).

CONCLUSIONS

In view of these results, extracorporeal membrane oxygenation seems to be the better option as mechanical circulatory support for right ventricular failure in heart transplantation.

Effects of sildenafil analogue UK 343-664 on a porcine model of acute pulmonary hypertension

BACKGROUND

Sildenafil (Pfizer Pharmaceuticals, Sandwich, Kent, UK) has been associated with pulmonary vasorelaxation. A more potent Sildenafil analogue (UK 343-664 [Pfizer Pharmaceuticals]) has been developed, but its effects in vivo have not been studied. This study evaluated the effects of UK 343-664 (Pfizer) during acute pulmonary hypertension.

METHODS

Fourteen adult swine were anesthetized with 1 minimum alveolar concentration isoflurane and were mechanically ventilated with an FIO(2) of 50%. End tidal CO(2) was maintained between 32 and 36 mm Hg. Micromanometer tipped catheters were placed in the ascending aorta, pulmonary artery, and right ventricle. Pulmonary flow was measured with a perivascular probe using transit time ultrasound.

RESULTS

Pulmonary hypertension was induced with a continuous infusion of the thromboxane analogue U46619. Animals were randomized into two groups. Group 1 (n = 9) received 500 microg of UK 343-664 (Pfizer) intravenously for more than 2 minutes. Group 2 (n = 5) served as the control group. Data were recorded continuously for 60 minutes. Statistical analyses were performed with the analysis of variance and t tests. A p less than 0.05 was considered significant.Pulmonary hypertension was achieved in all animals. The administration of UK 343-664 (Pfizer) was associated with a significant decrease in pulmonary artery pressure (30.3%; p < 0.05) and pulmonary vascular resistance (42%; p < 0.05) with mild systemic vasodilatation. These effects were partially maintained at 30 minutes (a 17.3% and 39% decrease, respectively; p < 0.05).

CONCLUSIONS

The administration of UK 343-664 (Pfizer) was associated with predominant pulmonary vasodilatation without systemic hypotension. This may represent a significant advance in the treatment of acute pulmonary hypertension. Potential clinical implications for this new phosphodiesterase enzyme type V (PDEV) inhibitor merit further study.

Intravenous and Intrapulmonary Administration of Honey Solution to Healthy Sheep: Effects on Blood Sugar, Renal and Liver Function Tests, Bone Marrow Function, Lipid Profile, and Carbon Tetrachloride-Induced Liver Injury

Safety of intravenous (i.v.) or intrapulmonary administration of different concentrations of honey and their effects on blood sugar, renal and liver function tests, bone marrow function, lipid profile, and carbon tetrachloride (CCl(4))-induced liver damage were studied. Healthy sheep of either sex, 6-8 months old, were assigned randomly into the following groups: sheep received i.v. infusion of 5% honey in normal saline at 10-day intervals for 50 days and were compared with sheep that received 5% dextrose; sheep received higher doses of honey (50 g of honey) by i.v. infusion daily for 10 days; sheep received four higher doses of honey (80 g each dose) for 2 weeks; sheep received subcutaneous injection of CCl(4) after four doses of i.v. infusion of 80 g of honey, and estimations of serum gamma-glutamyl transpeptidase (SGGT), serum glutamic oxaloacetic transaminase (SGOT), and serum glutamate pyruvate transaminase (SGPT) were performed daily for 10 days postinjection; sheep received i.v. infusion of 40 g of honey, and blood sugar estimation was performed for 3 h at 30-min intervals after infusion and compared with sheep that received 5% dextrose; sheep received rapid i.v. injection of 40% honey or 40% dextrose, and blood sugar was estimated before and after injection; sheep received various concentrations of honey in distilled water (0.5 mL/1.5 mL, 0.75 mL/1.75 mL and 1.2 mL/2.2 mL), and blood sugar estimation was performed before and after inhalation. Results showed that i.v. or intrapulmonary administration of honey did not cause any adverse effect. Intravenous delivery of honey by slow infusion caused improvement of renal and hepatic function, bone marrow function, and lipid profile. It reduced SGOT, SGPT, triglyceride, cholesterol, blood urea nitrogen, and blood sugar and elevated serum protein, serum albumin, hemoglobin, white blood cell, and neutrophil percentage. Similar results were obtained with the use of higher doses of honey. CCl(4) caused mild elevation of SGPT and SGGT and lowering of SGOT in sheep that received repeated i.v. administration of honey before administration of CCl(4), whereas in control sheep CCl(4) caused significant elevation of all the liver enzymes. Intravenous infusion of 40 g of honey caused elevation of blood sugar for 90 min postinfusion, whereas it decreased blood sugar at 2 and 3 h postinfusion as compared with fasting blood sugar. Dextrose caused significant elevation of blood sugar at all time intervals. Similar results were obtained with the use of 10% dextrose or 80 g of honey. Addition of honey to dextrose caused less hyperglycemia as compared with dextrose alone. Acute injection of 20 mL of 40% dextrose significantly elevated blood sugar for 3 h postinjection, whereas little elevation in blood sugar was obtained after injection of 40% honey; the difference between honey and dextrose was significant. Inhalation of honey caused significant lowering of blood sugar during and after inhalation as compared with fasting blood sugar and water inhalation. The effect was greater with a higher concentration of inhaled honey. It might be concluded that slow i.v. infusion or rapid i.v. injection of honey in different concentrations was safe and could lower blood sugar and improve renal, hepatic, and bone marrow functions and lipid profile. Intravenous honey had a hepatoprotective effect against CCl(4)-induced liver injury. Inhaled honey was safe and reduced blood sugar significantly.

[Perioperative implications of heart transplant]

Over the past 30 years, heart transplantation has evolved into a definitive therapy for patients with end-stage cardiomyopathy. However, perioperative management of patients undergoing heart transplantation remains a challenge for anesthesiologists. The presence of biventricular failure, arrhythmias and associated multisystem organ dysfunction may contribute to significant intraoperative hemodynamic instability prior to the initiation of cardiopulmonary bypass (CPB). Even after an uneventful transplantation, weaning from CPB may be difficult. Acute right ventricular failure can develop in the recipient secondary to pre-existing pulmonary hypertension. Treatment options frequently focus on therapeutic interventions directed towards decreasing pulmonary vascular resistance and improving right ventricular contractility. Intraoperative use of transesophageal echocardiography (TEE) enables the anesthesiologist to diagnose acute right ventricular failure early on and guide therapy. Concurrent pathology including kinking of the pulmonary artery anastomosis or valvular insufficiency in the transplanted heart can also be recognized and addressed. The number of patients undergoing cardiac transplantation is continually increasing. In addition, the use of more effective immunosuppressive agents has curtailed transplant rejection and permitted longer survival. Consequently, heart transplant recipients are more frequently presenting for non-cardiac surgical procedures. Thus, an understanding of physiological and pharmacological implications associated with heart transplantation is crucial for managing these patients in the perioperative period.

[Inhaled nitric oxide in the peroperative period and recovery]

OBJECTIVE

To analyse the current knowledge concerning use of inhaled NO (iNO) in anaesthesia and intensive care.

DATA SOURCE

References were obtained from Medline, recent review articles, the library of the department and personal files.

STUDY SELECTION

All categories of articles on this topic have been selected.

DATA EXTRACTION

Articles have been analysed for history, biochemistry, pharmacology, toxicity and clinical use of iNO.

DATA SYNTHESIS

Nitric oxide (NO) is a potent endothelium-dependent vasodilator. Because of its selective action on pulmonary circulation and the lack of effect on the systemic circulation due to its inactivation by haemoglobin, iNO has been presented as a new therapeutic agent in most diseases with pulmonary hypertension. During heart transplantation or surgical correction of congenital heart disease, iNO decreases pulmonary hypertension and improves altered right ventricular function. Studies included however small numbers of patients. Preliminary pharmacological studies demonstrated that iNO was able to decrease pulmonary hypertension and improve systemic oxygenation in adult respiratory distress syndrome. To date, none of the three multicentric studies performed was able to show any significant effect on duration of mechanical ventilation, morbidity or mortality. Finally, the sole demonstrated indication for iNO which remains is the persistent pulmonary hypertension of the newborn. Two multicentric studies have evidenced an improvement in systemic oxygenation and a reduced need for extracorporeal membrane oxygenation. In these two studies global mortality was however unchanged.

CONCLUSION

Persistent pulmonary hypertension is the sole demonstrated indication for iNO. Inhaled nitric oxide may be efficient in pulmonary hypertension, right ventricular dysfunction and severe hypoxemia. Inhaled nitric oxide must be considered as a rescue therapy or needs to be part of research protocols.

Intra-operative use of inhaled vasodilators: are there indications?

The US Food and Drug Administration and European authorities have recently approved inhaled nitric oxide for the treatment of neonates with hypoxic respiratory failure associated with pulmonary hypertension. In addition to this highly specific condition, there is an increasing 'off-label' use of inhaled nitric oxide and other inhaled vasodilators in the perioperative setting. Potential indications include right heart failure as a result of acute pulmonary hypertension in cardiac and non-cardiac surgery, the prevention of reperfusion injury in lung transplantation, the treatment of hypoxaemia during single-lung ventilation, and more recently, the treatment of sickle cell crisis.

Inhaled NO and prostacyclin during porcine single lung transplantation

BACKGROUND

Increased pulmonary vascular resistance (PVR) and decreased arterial oxygenation frequently complicate lung transplantation. Inhaled nitric oxide (NO) and aerosolized prostacyclin (PGI2) both dilate the pulmonary vasculature and improve oxygenation in adult respiratory distress syndrome. We investigated whether similar effects would occur during early reperfusion of a lung graft.

METHODS

Eighteen pigs underwent left lung transplantation. We measured blood flow distribution, mean pulmonary artery pressure, PVR, and gas exchange in each lung separately. Animals were randomized into three groups to receive NO (10 ppm/30 minutes, 40 ppm/30 minutes), nebulized PGI2 (25 microg/mL/30 minutes, 50 microg/mL/30 minutes), or no drugs (control).

RESULTS

In the transplanted lung, PVR was significantly higher than in the native lung. Pulmonary vascular resistance of the transplanted lung was lower in the NO and PGI2 groups in comparison with the control group. During the first hour of inhalation, NO decreased PVR more than PGI2. Neither drug improved oxygenation in the graft.

CONCLUSIONS

Nitric oxide and PGI2 decreased PVR of the transplanted lung slightly, but the effect did not produce a normal pressure in pulmonary vasculature.

Skin sympathetic neuroeffector response is attenuated dose-dependently by systemic prostaglandin E1 injection in humans

To clarify the effects of prostaglandin E1 (PGE1) on the vasoconstrictive responses, we compared the correlation between the amplitude of integrated skin sympathetic nerve activity (SSNA) and per cent reduction in skin blood flow (SBF) before and after the infusion of lipo PGE1 and placebo (bolus one-shot infusion, single blind study), and constant rate infusion of PGE1 (10 and 50 ng kg(-1) min(-1) by infusion pump, dose-dependency study) in ten healthy men. SSNA was recorded microneurographically from the median nerve simultaneously with SBF by laser Doppler flowmetry at the index fingertip. The measurement was conducted 30 min after injection of lipo PGE1 or placebo, and during the drip infusion of 10 and 50 ng kg(-1) min(-1) of PGE1 with maneuvers to enhance SSNA. The resting and activated skin blood flow were not significantly different between 10 ng lipo PGE1 and placebo administration, and between baseline and 10, 50 ng kg(-1) min(-1) of PGE1 injection. The vascular response, defined as the slope of regression line between logarithm of amplitude of integrated SSNA bursts and the reduction in SBF, was significantly suppressed by injection of lipo PGE1 as compared with that by placebo. It was also decreased dose-dependently by the constant rate infusion of PGE1 (10 and 50 ng kg(-1) min(-1)). We concluded that the intravenous injection of PGE1 attenuates vasoconstrictive responses to SSNA, and analysis of the relations between SSNA and vasoconstrictive response, i.e. the neuroeffector response, is suggested to be an important tool to assess the drug effect.