André Coetzee

Comparison of sodium nitroprusside- and esmolol-induced controlled hypotension for functional endoscopic sinus surgery

The purpose of this study was to compare surgical conditions for functional endoscopic sinus surgery (FESS) under general anaesthesia during controlled induced hypotension, using either sodium nitroprusside (SNP) or esmolol. Twenty patients, assigned to receive either of the drugs as the primary hypotensive agent, were studied. The same surgeon, blinded to the hypotensive agent used and the haemodynamic variables, performed all the operations. The surgeon used a category scale (0–5) to assess surgical conditions — a value of 2–3 being ideal. Patients were positioned in 5° reverse Trendelenburg position and the mean arterialblood pressure (MABP) was reduced in steps of 5 mmHg. The anaesthetist prompted category scale estimations by the surgeon following a change in any of the haemodynamic variables. Average category scale (ACS) values were compared between the two groups for four data groups, i.e., MABP > 65 mmHg (mild), 60–64 mmHg, 55–59 mmHg and 50–54 mmHg. Pre-treatment MABP was 79.8 ± 10.4 mmHg in the SNP group and 76.1 ± 6.8 mmHg in the esmolol group. At mild SNP-induced hypotension, surgical conditions were poor (ACS = 3.63 ± 0.22; mean ± SEM), while in the esmolol group, ideal surgical conditions (ACS = 2.94 ± 0.34) were recorded at MABP > 65 mmHg. The combined effects of increased venous drainage due to the reverse Trendelenburg position, hypotension as well as capillary vasoconstriction due to unopposed alpha-adrenergic effect on the mucous membrane vasculature in the esmolol group (as opposed to vasodilatation in the SNP group) probably caused the superior surgical conditions.RésuméCette étude vise à comparer pendant la chirurgie endoscopique fonctionnelle des sinus sous anesthésie générale, les conditions chirurgicales obtenues avec l’hypotension délibérée réalisée soit avec du nitroprussiate de soude (SNP), soit avec de l’esmolol. Vingt patients sont assignés à recevoir l’un ou l’autre des agents hypotenseurs. Un seul chirurgien, ignorant l’agent utilisé et les paramètres hémodynamiques, effectue toutes les interventions. Le chirurgien cote les conditions chirurgicales sur une échellle de catégories de 0 à 5, les valeurs 2 et 3 étant jugées idéales. Les patients sont placés en Trendélenbourg renversé a 5° et la pression artérielle moyenne (PAM) est réduite par paliers de 5 mmHg. L’anesthésiste demande au chirurgien son évaluation sur l’échelle de catégorie à chaque changement de paramètre hémodynamique. Les valeurs moyennes de l’échelle de catégorie (ECM) sont comparées entre les deux groupes pour quatre sous-groupes de données, c-à-d, PAM > 65 mmHg (légère), 60–64 mmHg, 55–59 mmHg et 50–54 mmHg. Avant la perfusion, la PAM est 79,8 ± 10,4 mmHg dans le groupe SNP et 76,1 ± 6,8 mmHg dans le groupe esmolol. En l’hypotension légère au SNP, les conditions chirurgicales sont pauvres (ECM = 3,63 ± 0,22, moyenne ± SEM), alors que dans le groupe esmolol, les conditions chirurgicales idéales (ECM = 2,94 ± 0,34) surviennent avec une PAM > 65 mmHg. Les effets associés du drainage veinewc en position de Trendélenbourg renversé, l’hypotension ainsi que la vasoconstriction capillaire causée par l’action alpha-adrénergique de l’esmolol sur les vaisseaux de la muqueuse dans ce groupe (contrairement à la vasodilatation dans le groupe SNP) sont, selon toutes probabilités, les causes des meilleures conditions chirurgicales.

Recurrence of cardiotoxicity after lipid rescue from bupivacaine-induced cardiac arrest

Accidental intravascular administration of bupivacaine during performance of a brachial block precipitated convulsions followed by asystole. The patient was rapidly resuscitated using cardiopulmonary resuscitation, supplemented by 150 mL of 20% lipid emulsion. Nonetheless, cardiac toxicity reappeared 40 min after completion of the lipid emulsion. In the absence of further lipid emulsion, amiodarone and inotropic support were used to treat cardiotoxicity. This case suggests that local anesthetic systemic toxicity may recur after initial lipid rescue. Since recurrence of toxicity may necessitate administration of additional doses of lipid emulsion, a sufficient quantity of lipid emulsion should be available when regional anesthesia is performed.

Moderate controlled hypotension with sodium nitroprusside does not improve surgical conditions or decrease blood loss in endoscopic sinus surgery

Abstract Study Objective: To determine if moderate controlled hypotension can improve the dryness of the surgical field in endoscopic sinus surgery. Study Design: Randomized, prospective study. Setting: University-affiliated hospital. Patients: 32 ASA physical status I and II adult patients undergoing endoscopic sinus surgery. Interventions: All patients were premedicated orally with chlorazepate. Patients in Group H received 12.5 mg captopril orally prior to surgery. Anesthesia was provided using an intravenous (IV) technique supplemented with nitrous oxide (N 2 O); anesthesia was maintained with boluses of 2 μg/kg fentanyl and a propofol infusion at rates between 3 and 9 mg/kg/h at the discretion of the anesthetist. In Group H, sodium nitroprusside was infused at a rate of 1 to 2.5 μg/kg/min to maintain moderate controlled hypotension with mean blood pressure of 65 to 75 mm Hg. Measurements and Main Results: Arterial blood pressure was assessed via the radial artery. Readings were recorded prior to intubation, immediately after intubation, at the start of surgery, then at 5, 15, 30, 45, and 60 minutes intraoperatively, and at the end of surgery. Intraoperative blood loss, dryness of the surgical field, adrenocorticotropic (ACTH) hormone, arginin-vasopressin (AVP), cortisol, and the preoperative and postoperative psychomotoric function were examined. At the start of surgery and thereafter, MAP increased in Group N but not in Group H. Throughout surgery, MAP was significantly lower in Group H than in Group N. Blood loss, dryness of the surgical field, ACTH, AVP, and cortisol levels, and psychomotoric function were not significantly different between the groups. Conclusion: Intravenous anesthesia supplemented with N 2 is as effective as moderate controlled hypotension when blood loss, visibility in the surgical field, ACTH, AVP, and cortisol are examined.

Halothane protects the isolated rat myocardium against excessive total intracellular calcium and structural damage during ischemia and reperfusion

A recent study from our laboratory demonstrated halothane to be a powerful protectant of the isolated rat heart during reperfusion after normothermic cardioplegic arrest. It was speculated that this protective effect might be due to prevention of excessive intracellular calcium. The aim of the present study was to evaluate the effect of halothane on the total intracellular calcium (Ca2+) content and on myocardial structure both at the end of normothermic cardioplegic arrest and at the end of reperfusion. Isolated perfused rat hearts were perfused for a control period of 30 min, followed by 40 min of normothermic cardioplegic arrest with or without reperfusion for 30 min. Halothane (1.5%) was administered continuously before and after arrest. Halothane caused a significant decrease of intracellular Ca2+ at the end of normothermic cardioplegic arrest and after reperfusion. Myocardial morphology was assessed by extensive light microscopy and ultrastructure was evaluated by electron microscopy. Grading of ischemic damage showed that exposure to normothermic cardioplegia resulted in marked ischemic injury, regardless of whether the hearts were treated with halothane. Reperfusion in the presence of halothane caused a significant reversal of ischemic damage and almost complete ultrastructural repair, whereas untreated hearts still exhibited severe edema, contracture, and contracture bands. Our results indicate that the beneficial effects of halothane on myocardial structural recovery during reperfusion is associated with a reduction in excessive intracellular Ca2+. The exact mechanism of this protective action is under investigation.

Arterial oxygenation and one-lung anesthesia.

Purpose of review In the presence of the obligatory shunt during one-lung ventilation, arterial oxygenation is determined by the magnitude of the shunt in addition to the oxygen content of the mixed venous blood coursing through that shunt. The present discussion aims to heighten awareness of factors determining arterial oxygenation during one-lung anesthesia, other than the magnitude of the shunt and dependent lung low-ventilation perfusion units. Recent findings A convenient way to increase mixed venous and thereby arterial oxygenation is to raise cardiac output. While this approach has achieved some success when increasing cardiac output from low levels, other studies have highlighted limitations of this approach when cardiac output attains very high levels. The effect of anesthesia techniques on the relationship between oxygen consumption and cardiac output could also explain unanswered questions regarding the pathophysiology of arterial oxygenation during one-lung anesthesia. Summary The effects of anesthesia techniques on oxygen consumption, cardiac output and therefore mixed venous oxygenation can significantly affect arterial oxygenation during one-lung anesthesia. While pursuing increases in cardiac output may, under limited circumstances, benefit arterial oxygenation during one-lung ventilation, this approach is not a panacea and does not obviate the necessity to optimize dependent lung volume.

Failure of allopurinol to improve left ventricular stroke work after cardiopulmonary bypass surgery

OBJECTIVE This study examined the effects of allopurinol on global left ventricular function after coronary artery bypass surgery. DESIGN A randomized prospective partially blinded study in 52 patients undergoing elective coronary artery bypass surgery. SETTING Conducted in a university-affiliated tertiary care facility. INTERVENTIONS Participants received 400 mg of allopurinol 18 hours and 400 mg of allopurinol orally 3 hours before surgery or no allopurinol. Patients then received a standard anesthetic technique consisting of target-controlled opiate infusion and inhalation anesthesia. Coronary artery bypass was performed using moderate hypothermia and oxygenated crystalloid cardioplegia. MEASUREMENTS AND MAIN RESULTS Global left ventricular function was assessed by means of left ventricular stroke work index (LVSWI) calculated before and after induction of anesthesia and after cardiopulmonary bypass at 15 minutes, 6, 12 and 24 hours. There was no difference in the LVSWI before or after surgery when the two groups were compared. CONCLUSIONS In this population sample, the use of preoperative allopurinol did not result in improved left ventricular stroke work after coronary artery bypass surgery.

Anesthetic modulation of myocardial ischemia and reperfusion injury in pigs: comparison between halothane and sevoflurane

PurposeHalothane offers protection against the reperfusion injury of the myocardium. This study compared sevoflurane with halothane in its potential to modulate the effects of acute severe ischemia and reperfusion on the myocardium.MethodsExperiments were conducted on 25 pigs. Anesthesia consisted of thiopental, vecuronium and fentanyl. The lungs were mechanically ventilated with oxygen and nitrogen. Animals were randomly allocated to receive either I MAC halothane or sevoflurane. A control group received fentanyl and pentobarbital. Regional myocardial function was measured with sonomicrometers. The left anterior descending coronary artery was occluded for 15 min followed by 60 min reperfusion.ResultsNeither halothane nor sevoflurane protected the heart against the effects of acute and severe regional myocardial ischemia. During reperfusion, 89% of the animals receiving sevoflurane suffered from ventricular fibrillation compared with 30% in the halothane group (P < 0.005). Five minutes into the reperfusion period the animals subjected to halothane anesthesia demonstrated an 88% recovery in regional myocardial systolic function while in the sevoflurane group the recovery was 40% of pre-ischemic control (P < 0.05).ConclusionHalothane is associated with less reperfusion arrhythmias and, in addition, recovery of regional myocardial function during reperfusion was more rapid in the presence of halothane than with sevoflurane.RésuméObjectifL’halothane offre une protection contre les lésions reliées à la reperfusion du myocarde. La présente étude a comparé le sévoflurane et l’halothane quant au pouvoir de moduler les effets de l’ischémie aiguë sévère et de la reperfusion du myocarde.MéthodeLes expériences ont été menées avec 25 porcs. On a utilisé du thiopental, du vécuronium et du fentanyl pour l’anesthésie. La ventilation mécanique des poumons s’est faite avec de l’oxygène et de l’azote. Les animaux, répartis de façon aléatoire, ont reçu I CAM d’halothane ou de sévoflurane. Un groupe témoin a reçu du fentanyl et du pentobarbital. La fonction régionale du myocarde a été mesurée à l’aide de sonomicromètres. Locclusion de 15 min de l’artère interventriculaire antérieure a été suivie de 60 min de reperfusion.RésultatsNi l’halothane ni le sévoflurane n’ont réussi à protéger le coeur des effets d’une ischémie régionale aiguë et sévère du myocarde. Pendant la reperfusion, 89 % des animaux qui avaient reçu du sévoflurane et 30 % de ceux qui avaient reçu de l’halothane ont souffert de fibrillation ventriculaire (P < 0,005). En cinq minutes de reperfusion, les animaux soumis à l’anesthésie à base d’halothane ont présenté un taux de récupération de la fonction systolique régionale du myocarde de 88% tandis que ceux qui avaient reçu du sévoflurane n’ont recouvré qu’à 40 % l’état préischémique enregistré (P < 0,05).ConclusionComparé au sévoflurane, l’halothane est associé à moins d’arythmie de reperfusion et à une récupération plus rapide de la fonction régionale du myocarde pendant la reperfusion.

Preservation of myocardial function and biochemistry after blood and oxygenated crystalloid cardioplegia during cardiac arrest

We compared the ability of blood cardioplegia and oxygenated crystalloid cardioplegic solutions to maintain regional left ventricle contractility and adenosine triphosphate levels after cardiopulmonary bypass. Ten baboons were subjected to 90-minute cardiopulmonary bypass conducted at 28 degrees C. Hemodynamic measurements were made before and after the bypass procedure, and biopsies for high-energy phosphate determinations were performed at different time intervals during and after bypass. The results showed improved maintenance of myocardial contractility (measured with the regional end-systolic pressure-length relationship) with the oxygenated crystalloid solution. Expressed as a percentage of values before bypass, contractility after bypass averaged 81.69% +/- 4.81% and 80.47% +/- 10.05%, respectively, after 10 and 20 minutes using the oxygenated crystalloid cardioplegia. For blood cardioplegia, the corresponding values were 71.9% +/- 8.73% and 64.99% +/- 8.60% (mean +/- standard error of the mean). The 10- and 20-minute postbypass values between the two groups differed significantly (t test, Welch modification: p = 0.0464 and p = 0.0342). Myocardial adenosine triphosphate level was higher immediately after induction of cardiac arrest when blood cardioplegia was used (blood cardioplegia, 6.82 mol.g wet wt-1; crystalloid cardioplegia, 4.95 mol.g wet wt-1; p = 0.0314), but values subsequently equalized.

Outcomes research in the ICU: An aid in defining the role of physiotherapy

The economic reality of consumers, funders, and regulatory agencies demanding evidence regarding the quality of care patients are receiving in the intensive care unit (ICU) will have an effect on many of the routinely used practices in ICU, including physiotherapy. Outcomes research is a method that has been used to obtain evidence for the medical and respiratory management of patients in ICU. An overview of the literature was conducted to answer the following questions: What is outcomes research? Which outcomes should be measured in the adult critical care environment? Which outcomes are physiotherapists currently including in research reports? Outcomes research is recognized by critical care specialists as a cost-effective method of determining what works in the real world. The value of physiologic measures is questioned, whereas the importance of patient centered, economic, and traditionally accepted outcome measures is increasingly being recognized. Most physiotherapy research reports still include physiologic measurements as the primary outcome of an intervention. Outcomes research provides researchers with the tools to define the role of the physiotherapist in the critical care environment. The outcomes measured must be relevant to patients, families, and funders. In attempting to arrive at the truth, I have applied everywhere for information, but in scarcely an instance have I been able to obtain hospital records fit for any purpose of comparison. If they could be obtained, they would enable us to decide many questions. They would show subscribers how their money was being spent, what amount of good was really done with it or whether the money was not doing mischief rather than good” (Florence Nightingale, Notes on a hospital, 1873)

The way in which a physiotherapy service is structured can improve patient outcome from a surgical intensive care: a controlled clinical trial

IntroductionThe physiological basis of physiotherapeutic interventions used in intensive care has been established. We must determine the optimal service approach that will result in improved patient outcome. The aim of this article is to report on the estimated effect of providing a physiotherapy service consisting of an exclusively allocated physiotherapist providing evidence-based/protocol care, compared with usual care on patient outcomes.MethodsAn exploratory, controlled, pragmatic, sequential-time-block clinical trial was conducted in the surgical unit of a tertiary hospital in South Africa. Protocol care (3 weeks) and usual care (3 weeks) was provided consecutively for two 6-week intervention periods. Each intervention period was followed by a washout period. The physiotherapy care provided was based on the unit admission date. Data were analyzed with Statistica in consultation with a statistician. Where indicated, relative risks with 95% confidence intervals (CIs) are reported. Significant differences between groups or across time are reported at the alpha level of 0.05. All reported P values are two-sided.ResultsData of 193 admissions were analyzed. No difference was noted between the two patient groups at baseline. Patients admitted to the unit during protocol care were less likely to be intubated after unit admission (RR, 0.16; 95% CI, 0.07 to 0.71; RRR, 0.84; NNT, 5.02; P = 0.005) or to fail an extubation (RR, 0.23; 95% CI, 0.05 to 0.98; RRR, 0.77; NNT, 6.95; P = 0.04). The mean difference in the cumulative daily unit TISS-28 score during the two intervention periods was 1.99 (95% CI, 0.65 to 3.35) TISS-28 units (P = 0.04). Protocol-care patients were discharged from the hospital 4 days earlier than usual-care patients (P = 0.05). A tendency noted for more patients to reach independence in the transfers (P = 0.07) and mobility (P = 0.09) categories of the Barthel Index.ConclusionsA physiotherapy service approach that includes an exclusively allocated physiotherapist providing evidence-based/protocol care that addresses pulmonary dysfunction and promotes early mobility improves patient outcome. This could be a more cost-effective service approach to care than is usual care. This information can now be considered by administrators in the management of scarce physiotherapy resources and by researchers in the planning of a multicenter randomized controlled trial.Trial registrationPACTR201206000389290