Pulmonary vasodilator responses to nicardipine: comparison with other vasodilators

Adaptive servo-ventilation suppresses elevation of C-reactive protein and sympathetic activity in acute uncomplicated type B aortic dissection

OBJECTIVES

The aim of this prospective, randomized study was to investigate the effects of adaptive servo-ventilation (ASV), based on haemodynamic parameters, sympathetic status and respiratory conditions in patients with acute uncomplicated type B aortic dissection.

METHODS

We enrolled 28 patients with acute uncomplicated type B aortic dissection requiring antihypertensive therapies, who had been admitted within 24 h from onset. Study subjects were randomly assigned either to the ASV group (n = 14) or to the non-ASV group (n = 14).

RESULTS

Antihypertensive therapy at an acute phase led to significant reduction in blood pressure in both groups. Heart rate significantly dropped in the ASV group. In the non-ASV group, noradrenaline (746 ± 343 to 912 ± 402 pg/ml, P = 0.033) and dopamine (30 ± 21 to 42 ± 28 pg/ml, P = 0.015) significantly increased at 1 h after admission. Low frequency/high frequency ratios significantly decreased in the ASV group (2.1 ± 1.6 to 1.7 ± 1.1, P = 0.045). During follow-up at the subacute period, pleural effusion significantly increased in the non-ASV group (649 ± 611 vs 190 ± 292%, P = 0.033). Peak C-reactive protein (CRP) had a significant positive correlation with pleural effusion volume (P = 0.039) and was significantly greater in the non-ASV group (15.5 ± 6.3 vs 8.5 ± 6.1 mg/dl, P= 0.009).

CONCLUSIONS

In acute type B aortic dissection, ASV was considered to have suppressed the development of sympathetic nervous activity, pleural effusion and elevation of peak CRP.

[Nicardipine induced hypoxia: role of hypoxic pulmonary vasoconstriction]

Nicardipine is a commonly used anti-hypertensive drug for acute situations. We report the case of a 55-year-old man with hypoxemic pneumonia, who presented a worsening of his hypoxia secondary to the injection of this calcium channel inhibitor (CCI). This side effect was probably caused by inhibition of hypoxic pulmonary vasoconstriction. Effects of CCI on pulmonary vessels are well-known. They don't induce clinically relevant hypoxemia in patients without acute pulmonary pathology. This case report shows that nicardipine can severely worsen haematosis of patients with acute hypoxia. CCI should probably not be used in such patients.

Effect of hypertonic saline pre-treatment on ischemia-reperfusion lung injury in pig

BACKGROUND

Hypertonic saline may be administered in the setting of lung transplantation but may affect the development of ischemia-reperfusion lung injury. This study investigated the effects of the pre-treatment by intravenous hypertonic saline in a pig model of single lung ischemia-reperfusion.

METHODS

Forty-three pigs (34 +/- 4 kg) under mechanical ventilation were randomly assigned to a left lung ischemia-reperfusion alone or preceded by 4-ml/kg 7.5% hypertonic saline, 33-ml/kg normal saline, or by the infusion of the vasodilator nicardipine. Animals without ischemia served as controls. After euthanasia, the left lung was sampled for histologic analysis and measurement of lung water and alveolar-capillary permeability.

RESULTS

Ischemia-reperfusion resulted in high-permeability pulmonary edema, hypoxemia, and increased interleukin-6 serum level. Hypertonic saline pre-treatment worsened pulmonary edema of the left lung (6.6 +/- 0.7 vs 4.8 +/- 0.8 ml/kg of body weight, p < 0.05) and resulted in a higher ratio of the protein level in the alveolar fluid to the serum protein level (0.41 +/- 0.04 vs 0.21 +/- 0.09, p < 0.05) and in a higher histologic damage score (11 [range, 9-11.75] vs 6.5 [range, 4.5-7.5], p < 0.05) without promoting pulmonary or systemic inflammation. Lung injury was affected neither by normal saline nor by nicardipine pre-treatment. Nicardipine did not influence the deleterious effect of hypertonic saline.

CONCLUSIONS

Pre-treatment by intravenous hypertonic saline worsened ischemia-reperfusion lung injury independently of its effects on the cardiac index or pulmonary circulation but probably through a direct effect of hyperosmolarity on endothelial permeability.

New Approaches to the Treatment of Congenital Vascular Malformations (CVMs)—A Single Centre Experience

OBJECTIVE

A retrospective review of the results of management of congenital vascular malformation (CVM) patients was made to assess the efficacy of newly introduced approaches.

METHODS

CVMs were categorised according to the Hamburg classification on the basis of minimally invasive tests. Invasive studies such as angiography are used to provide a road map for treatment. A new multidisciplinary approach was adopted, which accepts the integration of embolisation and sclerotherapy with traditional surgical therapy. Embolo-sclerotherapy was used as an independent therapy and as an adjunctive therapy to surgery.

RESULTS

Ninety-nine out of a total of 294 venous malformation patients underwent ethanol sclerotherapy with an immediate success rate of 98.8%, requiring 419 sessions of treatment. Interim results were excellent with no evidence of recurrence (mean follow-up 18.2 months). Most of the 25 patients treated surgically received pre-operative embolo-sclerotherapy, each with excellent interim results and minimum morbidity (mean follow-up 21.2 months). Forty-eight patients among 76 arteriovenous malformation patients underwent embolo-sclerotherapy independently (32/48) or adjunctively (16/48). Independent therapy on 32 produced excellent interim results (25/32) requiring a total of 171 sessions (mean follow-up 19.2 months). Eighty-nine extratruncal (ET) forms of lymphatic malformations received multiple sessions of sclerotherapy with OK-432 (108/120 sessions) or ethanol (12/20 sessions). OK-432 was used in 51 paediatric patients with the ET form and produced an excellent response in cystic type lesions (40/45) requiring 61 sessions with no evidence of recurrence (mean follow-up 24.2 months), whereas a mixed result was obtained in the cavernous type (3/6). OK-432 sclerotherapy was used as a pre-operative adjunctive therapy in 7 patients requiring 21 sessions with 17 cavernous type of the ET form, and produced good to excellent results after surgical excision of 14 lesions.

CONCLUSION

New approaches to the treatment of CVMs based on a multidisciplinary approach can improve results by fully combined surgical treatment with embolo-sclerotherapy.

Pulmonary responses to selective phosphodiesterase-5 and phosphodiesterase-3 inhibitors

OBJECTIVE

To compare the direct pulmonary vasodilating activity and specificity of phosphodiesterase-5 (zaprinast) and phosphodiesterase-3 (milrinone) inhibitors on the pulmonary vascular (PV) bed of the spontaneously breathing cat with an intact chest.

DESIGN

Prospective, randomized animal study.

SETTING

Laboratory of university hospital.

SUBJECTS

Experiments were performed in vivo in intact-chest, spontaneously breathing cats with controlled pulmonary blood flow and constant left atrial pressure.

INTERVENTIONS

The responses to intralobar injections of zaprinast and milrinone were investigated at low PV tone. PV tone was then increased by intralobar arterial infusion of a thromboxane A(2) mimic, U46619. Animals received intralobar bolus injections of zaprinast or milrinone, followed by continuous IV infusion of the drug, which was administered in incremental doses titrated to produce a 20% reduction in mean systemic arterial pressure.

MEASUREMENTS AND MAIN RESULTS

At low PV tone, zaprinast, but not milrinone, decreased lobar arterial pressure (LoAP). At elevated PV tone, both drugs caused dose-dependent decreases in LoAP; however, milrinone caused significantly less pulmonary vasodilation. Dose-related decreases in mean systemic arterial pressure were observed with milrinone, but not with zaprinast. When the continuous IV infusion was titrated to produce a 20% reduction in mean systemic arterial pressure, the decreases in lobar arterial pressure with zaprinast infusion were significantly greater than those produced by milrinone.

CONCLUSIONS

These data show that zaprinast and milrinone exert a direct in vivo vasodilator effect on the PV bed at low (zaprinast) and elevated (zaprinast and milrinone) PV tone; however, at elevated PV tone, the pulmonary vasodilator effect was greater with zaprinast then with milrinone. This suggests that phosphodiesterase-5 inhibitors may potentially offer a therapeutic alternative in the management of acute pulmonary hypertension.

The low resistance strategy for the perioperative management of the Norwood procedure

BACKGROUND

Postoperative course of the Norwood procedure is fragile because of an unstable pulmonary to systemic blood flow ratio caused by fluctuation of systemic and pulmonary vascular resistance.

METHODS

Twenty-seven patients with hypoplastic left heart syndrome who underwent the Norwood procedure from June 1998 to February 2002 were managed with the following low-resistance strategy. Intraoperative high-flow and low-resistance cardiopulmonary bypass was achieved with total avoidance of circulatory arrest and a large dose of chlorpromazine. In weaning from the bypass, pulmonary vascular resistance was maximally decreased by inspired oxygen fraction (100%), inhaled nitric oxide (20 ppm), and nitroglycerin (2 to 4 microg/kg/min). Then pulmonary blood flow was determined by adjusting the systemic to pulmonary shunt. Postoperatively, with continuous infusion of chlorpromazine and nitroglycerin as a systemic and pulmonary vasodilator, the inspired oxygen fraction and inhaled nitric oxide were tapered as the arterial oxygen saturation improved.

RESULTS

In most patients, inhaled nitrous oxide and inspired oxygen fraction were weaned within 3 days. The postoperative course was stable with minimum changes in circulatory and respiratory status for the survivors. Patients were extubated on a median of 6 postoperative days. Early mortality was 11.1% (3 of 27), and none of the patients died of hemodynamic deterioration.

CONCLUSIONS

The low resistance strategy is a simple and useful method for perioperative management of the Norwood procedure, minimizing fluctuation in both pulmonary and systemic vascular resistance and maintaining stable circulatory and respiratory status.

Intravenous nicardipine for treatment of postcoarctectomy hypertension in children

Our objective was to evaluate the efficacy of intravenous (IV) nicardipine for the treatment of postcoarctectomy hypertension in children with coarctation of the aorta. We carried out a retrospective review in a pediatric intensive care unit at a tertiary care children's hospital. The patients were children with coarctation of the aorta treated for postcoarctectomy hypertension. Children with postcoarctectomy hypertension defined as a systolic blood pressure >95th percentile for age measured by indwelling arterial catheter were treated with IV nicardipine. We measured change in mean arterial blood pressure (MAP), mean systolic and diastolic blood pressure, and mean heart rate (HR) from baseline after initiating treatment with IV nicardipine. The outcome measure was a reduction in MAP and mean systolic and diastolic blood pressure after treatment with IV nicardipine. During a 4-year period, 10 children met the study criteria. Median age was 3.25 months (range, 0.25 to 180 months). Initial median treatment dose of IV nicardipine was 1.0 micro g/kg/min (range, 0.5 to 6 micro g/kg/min); median dose used to control hypertension was 1.5 micro g/kg/min (range, 0.25 to 6 micro g/kg/min). Median duration of therapy was 26.3 h (range, 13 to 49 h). Treatment with IV nicardipine resulted in a 26.5% decrease in MAP from baseline during the first hour of treatment ( p = 0.0006). Mean systolic blood pressure decreased from 133 to 105 mmHg ( p = 0.005), and mean diastolic blood pressure decreased from 75 to 52.5 mmHg ( p = 0.001) during the first hour of therapy with nicardipine. There was a significant reduction ( p = 0.0005) in MAP during continued treatment with IV nicardipine. The mean HR of 150 remained unchanged during the first hour of therapy with nicardipine, and no significant change in mean HR or adverse effects was noted during continued therapy. Two children receiving other antihypertensive therapy demonstrated further reduction in their blood pressure when IV nicardipine was initiated. Tachycardia and hypotension were not observed in any child treated with IV nicardipine. We concluded that IV nicardipine reduced MAP with no significant change in mean HR and no adverse effects in patients with postcoarctectomy hypertension. Nicardipine produced a further reduction in MAP in children receiving other antihypertensive agents. Nicardipine is an effective agent for treatment of postcoarctectomy hypertension in children with coarctation of the aorta.

Advanced management of venous malformation with ethanol sclerotherapy: mid-term results

PURPOSE

This paper is an update of previously published data on the basis of a retrospective review of midterm results of ethanol sclerotherapy on 87 patients (January 1995 to December 2000) for assessment of its efficacy as an improved treatment method for venous malformation (VM). According to this assessment, VMs were defined with a new classification and studied with advanced diagnostic technology and an advanced care system.

METHODS

The average follow-up period was 24 months after completion of a multisession treatment (mean, 8.2 months). Classification of VM was based on a modification of the Hamburg classification. Advanced diagnostic technology, mostly noninvasive, was used on 226 of 520 patients with congenital vascular malformation registered at the Congenital Vascular Malformation Clinic at the Samsung Medical Center. Of the 226 patients with VM, 87 with infiltrating extratruncular lesions had a total of 399 sessions of sclerotherapy. Follow-up assessment with periodic clinical examinations by the multidisciplinary team was supplemented with body blood pool scans, duplex scans, and magnetic resonance imaging, according to protocol, once the multisession therapy was completed. Angiographic assessment was seldom included. The endpoint of this phase II study was 24 months.

RESULTS

Of 399 sessions, initial success was seen in 379 sessions (95.0%) and failure was seen in 20 sessions (5%). This was mostly caused by forced abandonment from technical difficulty in delivering ethanol safely to the lesion (eg, direct drainage of VM into normal deep vein system). Later results after completion of the multisession therapy with a minimum follow-up of 24 months on 71 VMs have shown no evidence of recurrence. Eighty-seven patients have shown the same results without recurrence on an average of 18.2 months of follow-up. Fifty-one minor to major complications, mostly skin damage, developed after 47 sessions among the 379 sessions (12.4% in 24/87 patients; 27.9%). However, complications resolved spontaneously or were managed successfully, except for one permanent facial nerve palsy and one peroneal nerve palsy.

CONCLUSION

Absolute ethanol sclerotherapy can deliver excellent results as an independent therapy to the infiltrating type of extratruncular form of VM, which was once taboo because of prohibitively high morbidity. Absolute ethanol may be accepted as an effective treatment method because no recurrence has been observed in the relatively long-term observation period and the morbidity has been acceptable. However, it should be reserved only for individuals and centers with expertise. The morbidity involved should be clearly understood and accepted by the patient or family, and the risk of acute and chronic complications, both major or minor, should be explained to the patient. Long-term assessment of the complication's sequelae is warranted.

Drug-induced vasodilation in an in vitro and in vivo study: the effects of nicardipine, papaverine, and lidocaine on the rabbit carotid artery

Extreme arterial vasoconstriction (vasospasm) is a common problem encountered in microvascular surgery. An ideal pharmacologic tool able to counteract ischemia during microsurgery should be easy to apply and exert its action both locally and distally in the microcirculation of the flap. We have compared in vitro and in vivo vascular properties of nicardipine, papaverine, and lidocaine in the rabbit carotid artery. In vitro, rings from the rabbit carotid artery (n = 7) were bathed in Krebs-Ringers solution and stretched progressively to an optimal tension of 3.7 to 4.2 g. The specimens were contracted with norepinephrine (1 microM), and a cumulative dose response curve was established. In vivo, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 35 animals using 9-0 nylon suture and standard microsurgical techniques. During and after the anastomoses, nicardipine (0.1, 0.01 mg topical, or 0.1 mg/hour IV), papaverine (30 mg/cc topical), and lidocaine (2% with and without epinephrine) were applied (blinded) at the anastomotic site in five rabbits each. Heparinized sodium chloride was used as topical irrigation for control and to clean the anastomosis. Blood flow changes were monitored continuously with the transonic Doppler for 30 minutes after the procedure. The systemic blood pressure was also monitored in a group of pilot experiments. A documented decrease in blood flow was noted in all animals after the microvascular anastomosis. Nicardipine and papaverine evoked a concentration-dependent relaxation to precontracted rings to norepinephrine. Nicardipine was greater than papaverine in inducing relaxation. Lidocaine demonstrated a biphasic response with low concentrations potentiating contraction. Systemic nicardipine and papaverine significantly increased the blood flow in the rabbit carotid artery. Topical application of nicardipine and lidocaine did not significantly alter the blood flow; however, the application of nicardipine demonstrates a trend toward increased flow. Lidocaine with epinephrine significantly decreased the blood flow. No drug was found to alter the blood pressure of the animals. Our results demonstrate that nicardipine and papaverine seem to be pharmacologic tools able to increase the blood flow in anastomotic arteries. In contrast, the use of 2% lidocaine as a spasmolytic agent should be re-evaluated, since this substance may act as a partial agonist.