Limited Cardiovascular Reserve Research Articles

A comparative study of unilateral vs bilateral spinal anaesthesia using hyperbaric bupivacaine with buprenorphine in unilateral inguinal hernia surgery

Unilateral spinal anaesthesia can be used for inguinal hernia surgery. The advantage is that it provides a stronger block on the side of surgery and accelerated recovery of the nerve block, with better maintenance of cardiovascular stability. Hence it can be a valuable technique for high-risk patients.
 The aim: This randomized controlled trial was designed to evaluate the onset and duration of Sensory and motor block in both unilateral and bilateral spinal anaesthesia and the adverse effects of buprenorphine given intrathecally with 0.5 % bupivacaine for Spinal anaesthesia in patients scheduled for unilateral inguinal hernia surgery.
 Materials and methods: it is a сomparative two group randomized clinical study with 60 patients with 30 patients in Group U (UNILATERAL) and 30 patients in Group B (BILATERAL) is undertaken to study the changes in haemodynamics and side effects. Whereas, within the group (for the unilateral group) comparison of the time taken to reach L1, T12, T10 and the Bromage time between the surgical side and non-surgical side sides of surgery was done.
 Results: T10 -T12 spinal anaesthesia was achieved in both groups; the average time to anaesthetic onset in the unilateral group was 5.27±1.2 min, and in the bilateral, it was 5.90±1.02 min (p-value=0.32). Sensory and motor block lasted longer in the bilateral group when compared to the unilateral group; the incidence of side effects was limited to the occurrence of hypotension and bradycardia in the unilateral group than in the bilateral group. The success rate of unilateral spinal anaesthesia in our study was 100 %.
 Conclusion: Because of haemodynamic stability and faster recovery characteristics of unilateral spinal block, it can be used as a suitable technique in patients with a limited cardiovascular reserve and for outpatient anaesthesia.

Attenuation of stress response to laryngoscopy and intubation: sublingual nitroglycerin spray vs intravenous fentanyl and sublingual nitroglycerin spray

Background: Laryngoscopy and tracheal intubation is invariably associated with certain cardiovascular changes such as tachycardia, rise in blood pressure and a wide variety of cardiac arrhythmias. 1 Such complications are highly detrimental in patients with limited cardiovascular reserve specially in geriatric and elderly population. Various pharmacological agents have been used to attenuate these stress responses but none has yet been considered ideal. Therefore, purpose of this study is to investigate the efficacy of sublingual Nitroglycerine spray alone and sublingual Nitroglycerine spray with intravenous Fentanyl to attenuate the pressor response to laryngoscopy and intubation in normotensive patients.Methods: A total of 120 ASA I and II patients of age group 18-60 years scheduled for elective surgical procedure under general anesthesia were randomly divided into 3 groups of 40 in each group. Group 1 control group, Group 2, received NTG sub-lingual spray (0.4mg/spray) two min. before induction, and Group 3 received inj. Fentanyl (2µg/kg) 5min before + NTG sub-lingual spray (0.4 mg/spray) 2min before induction. Vital parameters before and after induction and thereafter at specified time interval following laryngoscopy and intubation were recorded for comparison.Results: Demographic characteristics and baseline vital parameters in both the groups were comparable. Significant differences in mean arterial pressure (MAP) and heart rate (HR) were observed in between the groups during postintubation period.Conclusions: Combination of intravenous Fentanyl plus Nitroglycerin spray is more effective than NTG alone in attenuating the stress response following laryngoscopy and intubation.

Pregnancy complicated by valvular heart disease: an update.

Cardiovascular disease complicates ≈1% to 3% of all pregnancies and is responsible for 10% to 15% of maternal mortality. Although its prevalence is considered relatively low in pregnant women, heart disease is the most common cause of maternal mortality. Because more women with congenital or

Association of Intrapartum Cardiomyopathy with Adverse Cardiac Events in Pregnant Women in the U.S.

Pregnant women with cardiomyopathies have a limited cardiovascular reserve. The intrapartum period poses unique risks to this patient population, which may result in clinical decompensation with overt heart failure, arrhythmias, and maternal death.

Evaluation of aging on muscle blood flow in conscious healthy dogs by duplex Doppler ultrasonography

According to a study conducted on a population of 9,248 subjects, cardiac diseases are the second most prevalent cause of death in the dog. During the last decades, a common scenario has been the increase on life expectancy of dogs. The exact relationship between the negative modifications of cardiovascular function and the development of specific cardiovascular diseases is difficult to ascertain, and also, the effect of age per se on vascular impedance is important. It may result in limited cardiovascular reserve under conditions of increase demand in senescent animals. To evaluate the effect of age on the peripheral vasculature specifically, the objective of this study was to compare parameters of the regional blood flow as well as compliance and resistance indexes in the femoral arterial system of younger and older conscious healthy dogs by duplex Doppler ultrasonography. The data were collected from 16 mixed-breed dogs divided into two groups: young and old healthy dogs. In all dogs Doppler spectra blood flow patterns of the femoral artery were triphasic. Significant differences were not found between the parameters measured for young and old groups. Despite this, the average value of femoral flow volume in the older group was approximately 50% lower than the younger group. This finding could play an important role in limiting exercise response with age. In order to validate these speculations, further studies should be performed in aged dogs.

Tremores intra e pós-operatório: prevenção e tratamento farmacológico

Tremors can be an adverse effect of the surgical intervention and anesthesia. The incidence of postoperative tremors varies from 6.3% to 66%. Young age, male gender, the use of halogenated anesthetics, and prolonged anesthesia or surgical procedure are related with tremors. Tremors are involuntary and present as oscillating muscular activity aiming at increasing heat production. Postoperative tremors are a disagreeable complication related with increased morbidity. Tremors increase the metabolism, resulting in a 200% to 500% increase in oxygen consumption.The objective of this paper was to discuss the causes, prevention, and treatment of intra- and postoperative tremors in adults and children undergoing general anesthesia or neuroaxis anesthesia for surgical interventions.Tremors, along with nausea and vomiting, cause severe discomfort in the recovery room, besides being highly prejudicial because they generate an increase in the metabolism. Although the presence of tremors has not been directly related with cardiac morbidity, its prevention has become the subject of discussion and several scientific reports. Prevention and treatment of tremors should be implemented. Patients with limited cardiovascular reserve could develop lactic acidosis, mixed venous desaturation, and hypoxemia.

Evaluation of histamine release during constant rate infusion of morphine in dogs

ObjectiveTo evaluate histamine release and selected physiologic variables during constant rate infusion (CRI) of morphine in dogs. AnimalsFive healthy, conscious, intact female dogs. Material and methodsUsing a Latin square, repeated-measures design, dogs were randomly assigned to three treatment groups to receive a 4-hour CRI of saline (SAL), or a loading dose of morphine at 0.3 mg kg−1 (LM), or 0.6 mg kg−1 (HM), followed by an infusion of 0.17 mg kg−1 hour−1 (LM) and 0.34 mg kg−1 hour−1 (HM) respectively. Dogs received each of the three treatments at intervals of at least 7 days. Plasma histamine concentration, skin flushing, edema and wheals, heart rate and rhythm and non-invasive arterial blood pressure were measured before the loading dose and at 1, 2, 5, 15, 30, 60, 120, 180 and 240 minutes during the CRI, or at the time of occurrence. ResultsThe loading dose induced the highest histamine release in the HM group being statistically higher than the SAL group. The histamine release obtained in the LM group after the loading dose did not differ from SAL. During the infusion, plasma histamine levels were numerically higher in the LM group. Besides one dog that developed hypotension for 2 minutes after the loading dose in the HM group and one dog that showed occasional ventricular premature contractions during both morphine infusions, cardiovascular variables were similar among the three treatment groups. Conclusions and Clinical relevanceBoth doses of morphine induced variable histamine release with minimal adverse cardiovascular effects in these concious, healthy dogs. The plasma histamine levels obtained may be associated with significant hemodynamic changes in patients with limited cardiovascular reserve and sympathetic nervous tone.

Evaluation of histamine release during constant rate infusion of morphine in dogs

Previous studies have reported increased plasma histamine levels after single intravenous injections of morphine in dogs. The goals of this study were to evaluate histamine release and selected physiologic parameters during constant rate infusion (CRI) of morphine in dogs. Five adult healthy, conscious, intact female dogs were studied. Using a Latin square, repeated-measures design, dogs were randomly assigned to three treatment groups to receive either a loading dose of morphine at 0.3 mg kg−1 IV followed by a CRI of 0.17 mg kg−1 hour−1 IV (LM) or 0.6 mg kg−1 IV followed by a CRI of 0.34 mg kg−1 hour−1 IV (HM) or a bolus and a CRI of saline (SAL). Dogs received each of the three treatments at intervals of at least 7 days. Plasma histamine concentrations, skin flushing, edema and wheals, heart rate and rhythm and noninvasive arterial blood pressure were measured before and at 1, 2, 5, 15, 30, 60, 120, 180 and 240 minutes during the CRI or at the time of occurrence. Observer was blinded to the treatment given. Results showed that the highest histamine release occurred in the HM group at 1 minute after the loading dose (median 10.6 ng mL−1), which was significantly different from the LM (median 1.85 ng mL−1) and the SAL (median 0.26 ng mL−1) groups. By comparison, no other significant differences in plasma histamine were seen for the remaining time points, although during the CRI, plasma histamine levels were numerically highest in the LM group. One dog that developed hypotension for two minutes after the loading dose in the HM group and one dog showed occasional ventricular premature contractions during both morphine CRIs, otherwise cardiovascular parameters were similar among the three treatment groups. In conclusion, both doses of morphine induced variable histamine release with minimal cardiovascular adverse effects in these awake, healthy dogs. The plasma histamine levels obtained may be associated with significant hemodynamic changes in patients with limited cardiovascular reserve and reduced sympathetic tone.

Optimisation of oxygenation and tissue perfusion in surgical patients.

Surgical patients with limited cardiovascular reserve have much worse prognosis than patients with normal hearts. This review identifies 17 randomised controlled clinical trials that have investigated peri-operative therapy designed to increase tissue perfusion in surgical patients, many of whom have limited cardiovascular reserve. Although there are differences which make equating the trials complex, a total of 1974 patients have been enrolled in the studies and the odds ratio for reduction in mortality is 0.45 (95% confidence intervals 0.33-0.60). Further research needs to be undertaken in the identification of patients with limited cardiovascular reserve and for investigating proposed treatment strategies. Despite this, it appears that such patients have improved outcome if they are admitted to intensive care unit pre-operatively and have suitable therapy given to improve tissue oxygen delivery.

Optimization of oxygenation and tissue perfusion in surgical patients

Surgical patients with limited cardiovascular reserve have much worse prognosis than patients with normal hearts. This review identifies 17 randomized controlled clinical trials that have investigated peri-operative therapy designed to increase tissue perfusion in surgical patients, many of whom have limited cardiovascular reserve. Although there are differences which make equating the trials complex, a total of 1974 patients have been enrolled in the studies and the odds ratio for reduction in mortality is 0.45 (95% confidence intervals 0.33–0.60). Further research needs to be undertaken in the identification of patients with limited cardiovascular reserve and for investigating proposed treatment strategies. Despite this it appears that such patients have improved outcome if they are admitted to intensive care unit pre-operatively and have suitable therapy given to improve tissue oxygen delivery.

Is perioperative intensive care therapy useful in patients with limited cardiovascular reserve?

Surgical patients with limited cardiovascular reserve have much worse prognosis than patients with normal hearts. Fourteen randomized controlled clinical trials have investigated perioperative ICU therapy in surgical patients, many of whom have limited cardiovascular reserve. Although differences exist which make equating the trials complex, a total of 1,132 patients have been enrolled in the studies and the odds ratio for reduction in mortality is 0.32 (95% confidence intervals 0.21–0.47). Further research is needed in the identification of patients with limited cardiovascular reserve and proposed treatment strategies. These patients seem to have improved outcome if they are admitted to the intensive care unit preoperatively and are given suitable therapy to improve tissue oxygen delivery.

Force-frequency relation in patients with left ventricular hypertrophy and failure.

Our study demonstrated a loss of normal systolic contractile enhancement with increasing heart rate in patients with ventricular hypertrophy and symptoms of congestive heart failure. This decline in systolic reserve was not accompanied by worsening of diastolic function, and would therefore not seem to reflect underlying ischemia. Rather, it was more likely related to abnormalities of excitation-contraction coupling, particularly in light of findings of both increased post-rest potentiation and a reduced recirculation fraction. In contrast, mechanical restitution was unchanged, suggesting that alterations in Ca2+ release from the SR did not play a major role. Finally, we showed that increasing heart rate adversely affects the efficiency of ventriculo-vascular coupling in LVH hearts. This suggested another explanation of how dysfunction of cardiac force-frequency behavior can lead to limited cardiovascular reserve and contribute to clinical symptoms of exertional intolerance. Future efforts aimed at enhancing the force-frequency response, perhaps by enhancing the SR-ATPase, or manipulating its regulation, should prove helpful in ameliorating the limitations of LVH patients associated with rapid heart rate.

Haemodynamic effects of a parenterally administered N-3 polyunsaturated fatty acid emulsion in conscious dogs

Clinical interest in Polyunsaturated fatty acid emulsion (PUFA) has increased since it has been reported to have beneficial effects on the progression of cardiovascular disease. [1], hypertension [2], the inflammatory response and sepsis [3]. Little data is available on the acute haemodynamic effects of these emulsions, hence, we compared the haemodynamic effects of a standard long chain triglyceride emulsion (LCT) with those of a 20% PUFA emulsion. Five mongrel dogs were chronically instrumented for the measurement of heart rate (HR), left atrial (LAP), aortic (ABP) and left ventricular pressure (LVP), LVdP/dt, coronary blood flow velocity (CBF), cardiac output (CO), systemic vascular resistance (SVR) and wall thickening fraction (WTF). All animals received PUFA and LCT (7 mL kg−1 on separate days. The lipids were given i.v. over 30 min as a continuous infusion. Full heparinisation was accomplished by i.v. administration of 200 IU kg−1 of heparin prior to the study. Serial haemodynamic measurements, at preset times, were performed over 2 h after the start of the infusion. All data were analysed with repeated measures ANOVA followed by Student's t-test. The LCT emulsion increased LVdP/dtmax from 1940±195 to 2220±246 mmHg sec−1 (P<0.05), while all other parameters did not change. In contrast, PUFA did not change LVdP/dt max and mean ABP, while WTF% (Fig. 1) and CO (3.39±0.18 to 2.75±0.18 L min−1; P<0.05) decreased significantly. HR (82±3.7 to 141±14 bpm; P<0.05) and SVR (2278±105 to 3095±214 dyn−1s−1cm−5; P<0.05) increased significantly. All parameters returned to baseline after 2 h. (Figure 2)Fig. 2: (abstract 2). Wall Thickening Fraction (WTF) presented as a % from control, during and after a PUFA and a LCT emulsion in conscious dogs. Data are presented as a mean±sem.* P<0.05 vs. control, ! P<0.05 vs. LCT. n=5.We conclude that a parenterally administered LCT emulsion has positive inotropic effects while an intravenous PUFA emulsion depresses cardiac function and increases SVR. The pathophysiological mechanism has not been elucidated, but our data suggests potentially detrimental effects for patients with limited cardiovascular reserve.

Induction of anesthesia with fentanyl or fentanyl plus etomidate in high-risk patients

Anesthetic doses of fentanyl (46 +/- 1.3 micrograms/kg) and oxygen (group I) were compared to a moderate dose of fentanyl (3 to 4.7 micrograms/kg; mean = 3.54 +/- 0.1 micrograms/kg) + etomidate (0.4 mg/kg) intravenously (IV) (group II) during the anesthetic induction-endotracheal intubation sequence to evaluate hemodynamic changes and the incidence of side effects in 23 New York Heart Association class III and IV patients. Chest wall rigidity only occurred in group I (27%), and pain on injection (8%) and myoclonus (25%) only in group II. Patients in group I experienced transient, small increases in central venous pressure (immediately after induction) and mean pulmonary artery pressure (after tracheal intubation). Patients in group II had small, transient decreases in heart rate, mean arterial blood pressure and cardiac index after induction which returned to baseline levels immediately after tracheal intubation. The data indicate that a modest dose of fentanyl with etomidate is similar to a large (anesthetic) dose of fentanyl in terms of avoiding cardiovascular depression and preventing hemodynamic stimulation during and following the induction-tracheal intubation sequence. Our findings also demonstrate that these doses of fentanyl before etomidate decrease but do not eliminate side effects of etomidate. The results suggest that a modest dose of fentanyl followed by etomidate may be an attractive alternative to high doses of fentanyl in patients with limited cardiovascular reserve, especially when prolonged postoperative respiratory depression secondary to high doses of an opioid is undesirable.

Effets hémodynamiques du fentanyl lors d'anesthésies à deux concentrations d'enflurane

The cardiovascular effects of intravenous fentanyl were determined in eleven patients undergoing intra-abdominal surgical procedures under enflurane anaesthesia. The patients were curarized with pancuronium and ventilated with nitrous oxide (50 %) in oxygen. The systemic arterial pressure (P̄a) was measured by means of a left radial arterial catheter. The pulmonary artery pressure (P̄pa), the pulmonary wedge pressure (Ppw), the cardiac output, the pH and blood gases of mixed venous blood were measured by means of a thermodilution Swan-Ganz catheter. Before the surgical procedure, the measurements were carried out 10 and 20 min after the administration of 0.8 % enflurane, and 5 and 15 min after 5 μg · kg −1 intravenous fentanyl. During surgery, the measurements were repeated under 0.8 % enflurane, and then after 10 and 20 min of receiving 1.6 % enflurane, and 5 and 15 min after a second intravenous injection of fentanyl (5 μg · kg −1). Before and during surgery, the two concentrations (0.8 and 1.6 %) of enflurane had limited cardiovascular effects. Before surgery, under 0.8 % enflurane, the P̄a was steady, the heart rate (f c ) and the cardiac index (CI) decreased slightly. After the intravenous injection of 5 μg · kg −1 fentanyl, the cardiovascular depression was significant, with falls in f c (77 to 64 c · min −1 before surgery, 73 to 65 c · min −1 during surgery), CI (2.65 to 2.15 l · min −1 · m −2 before surgery, 2.50 to 2.22 l · min −1 · m −2 during surgery and P̄a (99 to 79 mmHg before surgery, 96 to 78 mmHg during surgery). Under 0.8 and 1.6 % enflurane anaesthesia, the effects of 5 μg · kg −1 fentanyl were a fall in the f c , P̄a and CI, with steady systemic vascular resistances. In patients without cardiovascular disease, the cardiovascular depression of i.v. fentanyl was of limited extent. This is probably not true in case of hypovolaemia or limited cardiovascular reserve.

Anesthesia-induced Changes in Regional Blood Flow: Implications for Drug Disposition

Anesthesia and anesthetics have the potential to influence drug pharmacokinetics through changes in body perfusion, hepatic and metabolic function, protein binding, and renal function. A chronically catheterized sheep preparation has been developed whereby blood flow through, and drug and oxygen extraction by, the heart and lungs, kidneys, gut, and liver can be measured. Thiopentone/halothane general anesthesia consistently decreased regional blood flow and extraction of test drugs by each of the organ groups. High subarachnoid anesthesia with tetracaine scarcely perturbed flow or function. Test drugs chosen were cefoxitin for kidney extraction, mepiridine for liver and kidney extraction, and chlormethiazole for liver, lung, and kidney extraction. It is suggested that the lack of effects of subarachnoid block on regional blood flow drug pharmacokinetics commend its use over general anesthesia for patients with limited cardiovascular or organ reserve. Further investigation of drug pharmacokinetics in surgical patients is still required so that deleterious effects are not experienced from drugs in use during the peroperative period.