Hypotensive actions of diltiazem and nitroprusside compared during fentanyl anaesthesia for total hip arthroplasty

The potential for inducing hypotension during fentanyl anaesthesia by administering either diltiazem (n = 7) or sodium nitroprusside (n = 7) was investigated during total hip arthroplasty. Haemodynamic variables were obtained in the lateral position before, during and after administration of the hypotensive agent. Diltiazem 0.15 mg·kg¹ given as an IV bolus followed by a 12.5 ± 3 µg·kg;^?1·min^?1 continuous infusion decreased mean arterial pressure (MAP) from 77 ± 11 mmHg to 63 ± 16 mmHg (p < 0.05) while other haemodynamic parameters showed only minor and insignificant changes. Hypotension continued for at least 30 min after the cessation of diltiazem. With sodium nitroprusside MAP decreased immediately from 81 ± 11 mmHg to 59 ± 9 mmHg (p < 0.01) and rapidly returned to its control value after cessation of the infusion. Cl and Qs/Qt rose significantly (p < 0.05) while the systemic vascular resistance index (SVRI) (p < 0.01) and pulmonary vascular resistance index (PVRI) (p < 0.05) fell significantly. The haemo dynamic profile was significantly different between hypotensive agents for MAP (p < 0.02), heart rate (HR) (p < 0.01), SVRI (p < 0.05), and PVRI (p < 0.05). HR was lower with diltiazem than with nitroprusside. A bradycardia less than 50 beatslmin was observed in five patients in the diltiazem group. MAP, SVRI and PVRI were lower with nitroprusside than with diltiazem. Diltiazem can induce and maintain moderate hypotension without tachycardia and decreased cardiac output in humans during fentanyl anaesthesia but the modulation of the level of arterial pressure and the depression of atrioventricular conduction are unpredictable.     

Hypotensive anaesthesia for microsurgery of the middle ear. A comparison between isoflurane and halothane

Fifty patients undergoing microsurgery of the ear were anaesthetised using thiopentone, nitrous oxide, oxygen and either halothane or isoflurane, via a low flow circle system with carbon dioxide absorption. Systolic blood pressure was reduced to approximately 70 mmHg by the additional use of increments of labetalol; the patients breathed spontaneously. The degree of haemostasis was assessed by the surgeon who was unaware which volatile agent was being used to supplement anaesthesia. Isoflurane, although it is a potent vasodilator produced operating conditions which were indistinguishable from halothane. Isoflurane is thus a safe and reliable alternative to halothane as a volatile agent used to supplement anaesthesia when using induced hypotension for middle ear surgery.     

Hypotensive anaesthesia in the oto-rhino-laryngological surgery using nitroglycerine (author's transl)

Of 66 patients undergoing hypotensive anaesthesia for oto-rhino-laryngological surgery, a sufficient low-pressure state was obtained in only 72% of patients when nitroglycerine was used. The cumulative nitroglycerine-consumption varied between 4.0 and 98.6 mg (0.05-1.698 mg/kg body weight). In 40 cases a normal or weak nitroglycerine-effect was accentuated by dihydralazine and the extend and time course of the interaction were investigated. The exceedingly marked additional effect of this substance indicates a mutual potentiation of both drugs. The maximum of the dihydralazine-action appeared after 25-35 minutes. In 16 further cases dihydralazine was given intravenously before the nitroglycerine infusion as a premedication, whereby always constant and satisfactory hypotension could be produced. A disadvantage of these combinations, occurring in several cases, was the decreased manoeuvrability of hypotension. The continuation of the long-term sodium nitroprusside-hypotension by using nitroglycerine was succesful. Even after nitroglycerine application longer than 3 hours (up to 6 hours) the acid-base-status remained normal.     

Hypotensive epidural anaesthesia in patients with preoperative renal dysfunction undergoing total hip replacement

Background. Hypotensive anaesthesia does not impair renal functionafter surgery in normal patients but there are no reports ofhypotensive anaesthesia in patients with chronic renal dysfunction(CRD). Methods. From a database of 1893 consecutive patients undergoingtotal hip replacement (THR) under hypotensive epidural anaesthesia(HEA) from 1999 to 2004, 54 patients were identified with CRD(preoperative serum creatinine     

Hypotensive anesthesia for scoliosis surgery in Jehovah's Witnesses

Hypotensive anesthesia has been advocated in spinal surgery for the purpose of diminishing operative blood loss. This study evaluated its effectiveness in 12 Jehovah's Witnesses undergoing Harrington instrumentation and fusion who refused transfusion. Previous series from this institute did not use deliberate hypotension because of routinely low blood loss. Compared with matched controls operated on under normotensive anesthesia, the Jehovah's Witness patients had lower absolute blood loss but also shorter operative time. Applied linear-regression analysis demonstrated that the diminished blood loss was associated with shorter operative time (P = 0.0002) rather than lower blood pressure. The majority of blood losses in spinal instrumentation with fusion occurs with decortication. This rapid bleeding occurs at venous pressures which are unaffected by arterial blood pressure manipulation. The authors conclude that spinal surgery is possible in Jehovah's Witnesses without transfusion and that operative technique is the single most important determinant of blood loss.     

Hypotensive anesthesia for spinal fusion with sodium nitroprusside

Deliberate induced hypotension for spinal fusion has been used in the past, but a search for better techniques continues. The authors used sodium nitroprusside by intravenous infusion to reduce the mean arterial pressure from 72 to 42 torr in 10 cases. This degree of hypotension provided an optimal surgical field and maintained adequate tissue perfusion as demonstrated by arterial oxygen tensions greater than 600 torr, no development of base deficit, and continuous urinary excretion. There were no complications related to hypotension. None of the patients received blood transfusions, whereas in the past, 2000 ml blood was usually required for this procedure.