Blood loss after total knee replacement. Effects of tourniquet release and continuous passive motion

We prospectively studied the cases of 121 patients who were being operated on for insertion of a unilateral total knee prosthesis with cement, and we placed them randomly in four groups. In Group I, the tourniquet was inflated throughout the operative procedure, and we released it postoperatively after a compressive dressing had been applied; a splint was used postoperatively for three days. In Group II, the tourniquet remained inflated throughout the operation, but no splint was applied postoperatively, and continuous passive motion was started immediately in the recovery room. In Group III, the tourniquet was released intraoperatively, and hemostasis was achieved by cauterization; postoperatively, a compressive dressing was applied, and a splint was used for three days. In Group IV, the tourniquet was released intraoperatively, hemostasis was established, and then the tourniquet was reinflated; a compressive dressing was applied, and continuous passive motion was started immediately in the recovery room. Hemoglobin and hematocrit values were monitored in all patients. Blood loss in suction drainage was recorded, and the total blood loss was calculated. The results show that total knee arthroplasty is associated with major loss of blood (mean, 1518 milliliters). The calculated blood loss for Groups I, II, and III averaged 1443 milliliters, while that for Group IV averaged 1793 milliliters. Loss in suction drainage correlated with total estimated blood loss and averaged 511 milliliters. The magnitude of blood loss after total knee arthroplasty should be appreciated, and special attention should be paid to the availability of adequate fluid and blood products, preferably blood donated by the patient preoperatively.     

Subtrochanteric femur fractures: a comparison of the Zickel nail, 95 degrees blade plate, and interlocking nail.

Seventy-nine nonconsecutive patients with subtrochanteric femur fractures were divided into three groups based on the method of fracture fixation. Group I consisted of 21 patients treated with a Zickel nail, Group II comprised 25 patients treated with a 95 degrees blade plate, and Group III included 33 patients treated with an interlocking nail. All patients in Group I and Group II had open reduction and internal fixation of their fractures. Ninety-four percent of the patients in Group III were treated by closed intramedullary nailing. The average operating times for Groups I, II, and III were 212, 272, and 181 min, respectively, while blood loss averaged 900, 1,500, and 600 ml for each group, respectively. Group I had one infection, ten malunions, and one nonunion. Group II had one infection, six malunions, and two nonunions. Group III had no infections, two malunions, and one nonunion. We conclude that closed interlocking nailing is the treatment of choice for acute nonpathologic subtrochanteric femur fractures in adults. There is decreased blood loss, reduced operating time, and fewer complications than with either the Zickel nail or the 95 degrees blade plate regardless of the fracture pattern or the degree of fracture comminution.     

Immediate strain shielding after femoral reaming and nailing. An in vivo study in rat femora

Following intramedullary reaming and nailing of rat femora, in vivo changes in dynamic strain were correlated with in vitro measurements of the bones. Reaming and nailing procedures were performed 2 days after implantation of unidirectional strain gauges at the anterior, mid-diaphyseal level of the femur. Structural stiffness of polyacetal nails were three times as stiff as intact bone. Reaming only decreased the median strain value by 26 percent, and this value was not reduced by insertion of polyacetal nails. Steel nailing reduced the strain by 74 percent. Tested by three-point bending, reaming increased stiffness by 5 percent at the anterior aspect. The presence of nails gave stiffness values that were 9 percent (polyacetal) and 56 percent (steel) higher than the reamed only condition. Our results indicate that steel nailing following reaming causes marked reduction in strain at the anterior, mid-diaphyseal surface, whereas reduction in strain caused by polyacetal nails is negligible.     

Intramedullary nailing with reaming to treat non-union of the tibia

The records of fifty-one patients who were treated by intramedullary nailing with reaming for non-union of the tibia were retrospectively reviewed. The fractures had been treated initially by closed reduction and immobilization in a cast, external fixation followed by immobilization in a cast, fixation by pins incorporated in a plaster cast, minimum internal fixation and immobilization in a cast, dynamic compression plating, or intramedullary nailing with or without reaming. After the initial treatment had failed, intramedullary nailing with reaming was done to gain union. Although closed nailing of the tibia was preferred, in thirty-three patients, the site of the non-union was opened to improve alignment by performing an osteotomy or to remove failed hardware. Bone grafts from the iliac crest were used in ten patients, and a fibular ostectomy or osteotomy was done in thirty-three. Of thirty-four open fractures (fourteen grade I, seven grade II, and thirteen grade III), eight were infected at the time of intramedullary nailing. The average time of the diagnosis of a non-union was 9.6 months; the average length of follow-up after nailing was twenty months. In forty-nine (96 per cent) of the fifty-one patients, tibial union occurred at an average of seven months postoperatively. Complications included persistent infection (three patients), acquired infection after intramedullary nailing with reaming (three patients), fracture of the nail that necessitated an additional operation (two patients), shortening of more than one centimeter (two patients), malrotation of more than 15 degrees (one patient), peroneal palsy (one patient), and amputation (one patient). When used to treat non-union of the tibia, intramedullary nailing with reaming can produce union as effectively as other alternatives, while enabling the patient to function more normally without external immobilization or walking aids.     

Heterotopic ossification about the hip after intramedullary nailing for fractures of the femur

A prospective study of 100 consecutive unilateral fractures of the shaft of the femur was performed to delineate the incidence of, and the factors predisposing to, heterotopic ossification about the hip after intramedullary nailing. Bone debris from reaming of the endosteal canal is deposited in the soft tissues surrounding the site of insertion of the nail, and we postulated that this debris may stimulate the formation of heterotopic bone and that decreasing the amount of debris left in the tissues after nailing may decrease the amount of heterotopic ossification. To test this theory, the patients were treated with routine intramedullary nailing and were randomly divided into two groups. In Group I, the operative incision was irrigated with 250 milliliters of normal saline solution with use of a bulb syringe before the wound was closed, and in Group II, the incision was irrigated with 3000 milliliters of normal saline solution with use of pulsatile lavage. The two groups were similar in all other respects. Eighty patients (eighty fractures; forty in Group I and forty in Group II) were available for follow-up and were evaluated in a blind fashion after the fracture had united. A grading system that was based on the length of the heterotopic ossification, as measured on antero-posterior radiographs of the hip, was used. In thirty-two of the patients (40 per cent), no heterotopic ossification developed, whereas minimum or mild ossification developed in twenty-seven patients (34 per cent). Moderate ossification developed in twelve patients (15 per cent) and severe ossification, in nine patients (11 per cent).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the effect of reamed and unreamed locked intramedullary nailing on blood flow in the callus and strength of union following fracture of the sheep tibia

This study was performed to compare the effects of reamed and unreamed locked intramedullary nailing on blood flow in the callus and early strength of union in a fractured sheep tibia model. After the creation of a standardized short spiral fracture by three-point bending with torsion, each tibia was stabilized by the insertion of a locked intramedullary nail. Ten animals were allocated randomly into two groups: one that had reaming prior to nail insertion and one that did not. Blood flow was measured in real time with use of laser Doppler flowmetry. Endosteal perfusion was determined at the fracture site before and after nail insertion. Perfusion of the callus was measured at three locations (proximal diaphysis, fracture site, and distal diaphysis) and at three time intervals (2, 6, and 12 week follow-up). All animals were killed 12 weeks postoperatively, and the tibiae were tested to failure in four-point bending. Nailing with reaming resulted in a larger decrease in overall endosteal perfusion than nailing without reaming (p < 0.015). The presence or absence of reaming did not affect blood flow within fracture callus. Perfusion of callus was greatest at 6 weeks of follow-up. Bending strength and stiffness were the same in both groups at 12 weeks. The study demonstrated that perfusion of callus and early strength of union are similar following intramedullary nailing with or without reaming.     

Early derangements of arteriovenous anastomotic and capillary blood flow in the canine hindlimb induced by supplemental pentobarbital anesthesia

Vasoactive effects of supplemental pentobarbital anesthesia in the canine hindlimb microcirculation were documented in two groups of animals previously anesthetized with 30 mg/kg pentobarbital: Group I with a 5 mg/kg intravenous (iv) bolus of pentobarbital (n = 8) and Group II with a 5 mg/kg 2-min iv infusion of pentobarbital (n = 7). In Group I, measurements at baseline (BL) and 5, 15, 20, and 30 min (min) following pentobarbital administration included cardiac output, mean arterial pressure, total peripheral vascular resistance, common femoral artery flow (CFAQ) and resistance (CFAR), percentage hindlimb arteriovenous anastomotic shunt (AVA%), absolute shunt flow (AVAQ), and hindlimb nutrient capillary flow (NCQ). In Group II these same measurements were made, but the study was continued until all hindlimb hemodynamic parameters returned to control values. CFAQ, AVA%, AVAQ, and NCQ were significantly increased, and CFAR was decreased in both groups. CFAQ and NCQ remained significantly elevated at 30 min in Group I. In Group II CFAR, AVA%, and AVAQ remained elevated at 30 min, but did return to BL by 40 min, as did all other hindlimb hemodynamic parameters measured. Pentobarbital resulted in both AVA and arteriolar dilation, with an increase in the percentage total flow distributed to AVAs. These alterations of microcirculatory flow should be considered during investigations of the distribution of peripheral blood flow, as well as during metabolic studies assessing arteriovenous substrate differences, if interpretative errors are to be avoided.     

High cervical spinal cord stimulation (CSCS) increases regional cerebral blood flow after induced subarachnoid haemorrhage in rats.

The effects of high cervical spinal cord stimulation (cSCS) on regional cerebral blood flow (rCBF) were investigated after experimentally induced subarachnoid haemorrhage (SAH) in rats by the means of (99m)Tc-HMPAO. The experiments were carried out on a total of 24 Wistar rats, divided in three groups [group I: control without SAH, group II: SAH, group III: SAH and cSCS]. (99m)Tc-HMPAO was administered intravenously (group II/group III) 48 hours after induction of SAH. In group III, (99m)Tc-HMPAO was given after 3 hours of cSCS. All animals were sacrificed 30 minutes after application on (99m)Tc-HMPAO. Radioactivities were determined in blood, cerebrum and cerebellum. The ratio cerebrum/blood and cerebellum/blood was calculated to ascertain "extraction rate" in the sample differentially. The following mean values were calculated for the cerebellum/blood ratio: Group I: 1.06, SD: 0.21; Group II: 0.66, SD: 0.21; Group III: 1.00, SD: 0.37. Comparing the mean values a highly significant difference could be found between group II and III (p = 0.007) and between group I and II (p = 0.0019), respectively. Calculations of the cerebrum/blood ratio revealed similar results. After SAH cSCS enhances cerebral and cerebellar blood flow in rats. Possibly, cSCD constitutes a new therapeutic approach in the treatment of disturbed regional cerebral blood flow after SAH.     

Intravenous lidocaine and ephedrine, but not propofol, suppress fentanyl-induced cough

PURPOSE: The aim of this study was to evaluate the effectiveness of lidocaine, propofol and ephedrine in suppressing fentanyl-induced cough. METHODS: One hundred and eighteen patients were randomly assigned into four groups and the following medications were given intravenously: patients in Group I (n = 31) received normal saline 2 mL, Group II (n = 29) received lidocaine 2 mg.kg(-1), Group III (n = 30) received propofol 0.6 mg.kg(-1) and Group IV (n = 28) received ephedrine 5 mg. At one minute after the study medication, fentanyl 2.5 microg.kg(-1) was given intravenously within two seconds. The occurrence of cough and vital sign profiles were recorded within two minutes after fentanyl bolus by an anesthesiologist blinded to study design. RESULTS: Sixty-five percent of patients in the placebo group had cough, whereas the frequency was significantly decreased in Groups II (14%) and IV (21%). Although a numerically lower frequency of cough was noted in Group III (37%), it was not statistically different from that of the placebo group. SpO(2) decreased significantly in patients of Group III compared to placebo; one patient experienced hypoxemia necessitating mask ventilation. Patients in Group III showed a decrease in heart rate and systolic blood pressure (2 beats.min(-1) and 8 mmHg vs baseline). Patients in Group IV showed an increase in both measurements (5 beats.min(-1) and 8 mmHg vs baseline). No truncal rigidity was observed throughout the study. CONCLUSIONS: Intravenous lidocaine 2 mg.kg(-1) or ephedrine 5 mg, but not propofol 0.6 mg.kg(-1), was effective in preventing fentanyl-induced cough. The results provide a convenient method to decrease fentanyl-induced cough.     

Preparation of the left ventricle for anatomical correction in patients with simple transposition of the great arteries. Surgical guidelines

Pulmonary artery banding in combination with an aortopulmonary shunt was performed on 16 patients with simple transposition of the great arteries to prepare the left ventricle for anatomical correction. Three groups were identified after operation: Group I (four patients) had increased pulmonary blood flow and tight pulmonary artery banding; Group II (four patients) had increased pulmonary blood flow and moderate pulmonary artery banding; Group III (eight patients) had normal pulmonary blood flow and moderate pulmonary artery banding. Postoperative low cardiac output was present in all patients in Group I, whereas mild heart failure was present in two patients in Group II and in two in Group III. There was one hospital death (6%). The follow-up period was 125 patient-months. Left ventricular systolic pressure rose from 63 +/- 11 torr before the operation to 101 +/- 35 torr after the procedure in Group I (p less than 0.05), from 59 +/- 10 to 93 +/- 33 torr in Group II (p less than 0.05), and from 55 +/- 10 to 84 +/- 16 torr in Group III (p less than 0.005). The increase in left ventricular muscle mass was from 44 +/- 2 gm/m2 preoperatively to 108 +/- 12 gm/m2 after operation in Group I (p less than 0.01), from 43 +/- 3 to 93 +/- 8 gm/m2 in Group II (p less than 0.02), and from 46 +/- 3 to 55 +/- 14 gm/m2 in Group III (p = no statistically significant difference). The postoperative change in left ventricular end-diastolic volume was from 100% +/- 17% to 133% +/- 23% of normal in Groups I and II (p less than 0.05) and from 123% +/- 29% to 107% +/- 36% of normal in Group III (p = no statistically significant difference). In preparing the left ventricle for anatomical correction, avoidance of severe pulmonary artery banding decreases the incidence of postoperative myocardial dysfunction, a moderate degree of volume overload and pulmonary artery banding provides the most effective stimulus for ventricular growth, and a small to moderate atrial septal defect is advantageous because it ensures the volume preload necessary for the development of the left ventricle.     

The effect of acute and chronic glucocorticoid excess on leucine kinetics and protein turnover in vivo

The present studies were undertaken to assess the effects of excess cortisol on amino acid exchange in the conscious dog. Three groups of 18-hr fasted dogs with catheters chronically implanted in the femoral artery were studied: Group I (n = 6) received saline; Groups II and III (n = 5, each) received ACTH intravenously (1 U/min) for 7 hr; in addition, Group III received ACTH, 500 U/day intramuscularly for 4 days. Leucine rates of appearance (Ra) and clearance were measured using a constant infusion of L-4,5-[3H]leucine. ACTH treatment resulted in a 9-fold increase in plasma cortisol in Groups II and III (from 2 +/- 1 to 18 +/- 1 and 17 +/- 2 micrograms/dl, in II and III, respectively P less than 0.001), with no effect on either plasma insulin or glucagon. Plasma leucine (mmole/liter) increased from 118 +/- 6 (I) to 153 +/- 6 (II, P less than 0.005) to 275 +/- 35 (III, P less than 0.001). Leucine Ra (micromoles/kilogram/minute) did not change in II, but rose by 39% (P less than 0.005) in III. Clearance (milliliters/kilogram/minute) dropped from 25 +/- 2 (I) to 18 +/- 2 (II, P less than 0.005), to 15 +/- 2 (III, P less than 0.001). It is concluded that acute elevations of cortisol increased plasma leucine only by inhibiting its rate of disposal, whereas chronic elevations had a dual effect; they inhibited leucine disposal and increased its entry into the plasma compartment, suggesting an inhibition of protein synthesis and stimulation of protein breakdown.     

Increased locoregional blood flow in brain tumors after cervical spinal cord stimulation

OBJECT: Patients with high-grade gliomas have poor prognoses following standard treatment. Generally, malignant brain tumors have a decreased blood flow that results in increased resistance to radiation and reduced delivery of chemotherapeutic agents and oxygen. The aim of the present study was to assess the effect of spinal cord stimulation (SCS) on locoregional blood flow in high-grade tumors in the brain. METHODS: Fifteen patients (11 with Grade III and four with Grade IV brain tumors) had SCS devices inserted prior to scheduled radiotherapy. Both before and after SCS, the patients underwent the following procedures: 1) single-photon emission computerized tomography (SPECT) scanning; 2) middle cerebral artery (MCA) blood flow velocity measurements (centimeters/second) with the aid of transcranial Doppler (TCD) ultrasonography; and 3) common carotid artery (CCA) blood flow volume quantification (milliliters/minute) based on time-domain processing by using color Doppler ultrasonography. The indices demonstrated on SPECT scanning before SCS were significantly lower (p < 0.001) in tumor sites compared with those in peritumoral sites (32%) and healthy contralateral areas (41%). Poststimulation results revealed the following: 1) a mean increase of 15% in tumor blood flow in 75% of patients (p = 0.033), as demonstrated on SPECT scanning: 2) a mean increase of greater than 18% in systolic and diastolic blood flow velocities in both tumorous and healthy MCAs in all but one patient (p < 0.002), as exhibited on TCD ultrasonography; and 3) a mean increase of greater than 60% in blood flow volume in tumorous and healthy CCAs in all patients (p < 0.013), as revealed on color Doppler ultrasonography studies. CONCLUSIONS: Preliminary data show that SCS can modify locoregional blood flow in high-grade malignant tumors in the brain, thus indicating that SCS could be used to improve blood flow, oxygenation, and drug delivery to such tumors and could be a useful adjuvant in chemoradiotherapy.     

The effect of intravenous fixed-dose heparin during total hip arthroplasty on the incidence of deep-vein thrombosis. A randomized, double-blind trial in patients operated on with epidural anesthesia and controlled hypotension

Heparin was given in fixed doses intravenously during unilateral primary total hip-replacement operations in a prospective, double-blind trial to assess the effect on the incidence of deep-vein thrombosis. One hundred and fifty patients were randomly assigned to one of two groups before the operation. Twenty-four patients were excluded from the study, leaving 126 patients. Group I consisted of sixty-six patients who received saline solution intravenously, and Group II comprised sixty patients who received heparin. All patients had epidural anesthesia with controlled hypotension. Fixed doses of heparin were administered five minutes before the operative incision was made and every thirty minutes throughout the operation. Mean arterial pressures were maintained at between fifty and sixty millimeters of mercury in all patients. Ascending venography was done on the seventh day after the operation. The incidence of deep-vein thrombosis was 24 per cent (sixteen of sixty-six patients) in Group I and 8 per cent (five of sixty patients) in Group II; the difference is significant (p = 0.03). The intraoperative loss of blood averaged 220 +/- 79 milliliters in Group I compared with 269 +/- 109 milliliters in Group II. An average of less than one unit of blood was transfused for each patient in each group. Postoperatively, there was no difference between the groups with regard to the amount of drainage that was collected in a Hemovac device or the values for hematocrit.     

The use of esmolol and magnesium to prevent haemodynamic responses to extubation after coronary artery grafting

BACKGROUND AND OBJECTIVE: The haemodynamic responses during extubation can cause complications after open-heart surgery. In this study, we aimed to examine the effect of esmolol and magnesium before extubation on these haemodynamic responses. METHODS: Following the approval of local Ethics Committee, 120 patients having coronary artery bypass grafting with extubation in the intensive care unit were included in the study. Patients were allocated to receive esmolol 1 mg kg-1 (group I, n = 40), magnesium 30 mg kg-1 (Group II, n = 40) or normal saline (Group III, n = 40). Study medication was administered as a 20-min infusion in a volume of 20 mL. Patients were extubated just after termination of the infusion. Heart rate, blood pressure and central venous pressure were recorded prior to drug administration, before extubation, during extubation and 1 min after extubation. RESULTS: Heart rate was lower in Group I than in Groups II (P < 0.05) and III (P < 0.001) and lower in Group II than in Group III (P < 0.05) during extubation. It was also lower in Group I than in Group III (P < 0.05) after extubation. Systolic blood pressure was lower in Group I than in Groups II and III (P < 0.001) during extubation. Diastolic blood pressure was higher in Group III than in Groups I and II during extubation (P < 0.001) and after extubation (P < 0.05). Mean arterial pressure was lower in Group I than in Groups II and III (P < 0.001) during extubation, lower in Group II than in Group III (P < 0.05) during extubation and lower in Group I than in Group III (P < 0.05) after extubation. CONCLUSION: We found that using esmolol before extubation following coronary artery bypass graft surgery prevents undesirable haemodynamic responses while magnesium reduces undesirable haemodynamic responses but does not prevent them.     

Limitations of conventional nailing

The ideal case for conventional closed nailing consists of: Isthmal fractures or fractures in which the isthmus can be extended by reaming or fractures with inherent stability by virtue of cortical interdigitations; closed and open type I and II; transverse, comminution grade I, II, and some grade III. Some segmental and short oblique fractures are amenable to conventional nailing. The canal length and geometry should be studied to avoid mishap in the operating room and the proper equipment. assembled along with a well trained team. Once these prerequisites have been met, conventional nailing will prove successful for the majority of patients and fractures of the femoral shaft.     

Femoral bone blood flow after reaming and intramedullary canal preparation: a canine study using laser Doppler flowmetry

This study was conducted to determine the effect of intramedullary reaming and canal preparation on bone blood flow in the proximal femur. Thirty-five adult dogs were randomly assigned to have their intramedullary canals prepared after reaming in the following manner: group 1, ream only; group 2, lavage; group 3, methylmethacrylate cement introduction; group 4, cement pressurization after placing a cement restrictor; group 5, lavage then cement introduction; and group 6, lavage then cement pressurization. Bone blood flow was measured at both metaphyseal and diaphyseal sites by using laser Doppler flowmetry before reaming, after reaming, after lavage, after cementing, and at 6 weeks after the procedure just before euthanasia. Reaming significantly decreased bone blood flow in the diaphysis (P = .046) but not in the metaphysis. Cement introduction and cement pressurization both significantly decreased bone blood flow in the metaphysis (P = .035, P = .004) and diaphysis (P = .007, P = .029). Pressurization of cement had a significantly greater relative effect than cement introduction alone in the diaphysis (P = .006) but not in the metaphysis. Lavage had no effect on bone perfusion. Bone blood flow was significantly increased at 6 weeks after the initial procedure in both the metaphysis (P = .049) and the diaphysis (P = .004). The results suggest that reaming decreases diaphyseal cortical but not metaphyseal bone blood flow significantly, whereas lavage has no effect. Cement introduction with or without pressurization has a significant detrimental effect on metaphyseal and diaphyseal blood flow. These findings have implications for intramedullary nailing and for canal preparation when performing arthroplasty.     

Evaluation of brain-stem dysfunction following severe fluid-percussion head injury to the cat

The degree of brain-stem dysfunction associated with high-level fluid-percussion injury (3.0 to 3.8 atm) was investigated in anesthetized cats. Measurements were made of the animals' intracranial pressure (ICP) pressure-volume index (PVI), far-field brain-stem auditory evoked responses (BAER's), and cerebral blood flow (CBF). The animals were classified into two groups based on the severity of neuropathological damage to the brain stem after trauma: Group 1 had mild intraparenchymal and subarachnoid hemorrhages and Group 2 had severe intraparenchymal and subarachnoid hemorrhages. The ICP values in Group 1 were insignificantly lower than those in Group 2, while the PVI values in Group 2 were clearly lower (p less than 0.05). Immediately after the injury, peaks II, III, and IV of the BAER's demonstrated a transitory and marked suppression. One Group 1 and two Group 2 animals showed the disappearance of peak V. In Group 1, the latencies of peak II, III, and IV gradually increased until 60 to 150 minutes postinjury, then returned to 95% of baseline value at 8 hours; however, the animals in Group 2 showed poor recovery of latencies. Two hours after brain injury, the CBF decreased to 40% of the preinjury measurement in both groups (p less than 0.001). In contrast to Group 2, the CBF in Group 1 returned to 86.8% of the preinjury measurement by 8 hours following the injury. Changes in PVI, BAER, and CBF correlated well with the degree of brain-stem injury following severe head injury. These data indicate that high-level fluid-percussion injury (greater than 3.0 atm) is predominantly a model of brain-stem injury.     

The effect of the pneumatic antishock garment (PASG) on hemodynamics, hemorrhage, and survival in penetrating thoracic aortic injury

To determine if the increased blood pressure associated with application of a pneumatic antishock garment (PASG) affects outcome in thoracic hemorrhage, we assessed hemodynamics, blood loss, and survival in three groups of eight anaesthetized piglets with a 2.5-mm laceration of the descending thoracic aorta. Baseline measurements were made before aortic hemorrhage. During one hour of aortic hemorrhage or until death of the animal, the PASG was not inflated in Group I while the PASG in the other two groups was inflated to maintain carotid artery pressure at 15 torr below baseline (Group II) and at baseline (Group III), respectively. Survival was 100% in Group I, 50% in Group II, and 0% in Group III. Hemorrhage at 22.5 +/- 4.0 mL/min stopped after 18-24 minutes in Group I; the survivors in Group II bled at a rate of 32.5 +/- 3.0 mL/min compared with 43.6 +/- 4.0 mL/min over 26-35 minutes in the Group II nonsurvivors. Group III pigs bled at 107.5 +/- 8.0 mL/min over the 10-18 minutes of survival. The intended blood pressure could not be maintained beyond 30 minutes. Bleeding stopped in Group I when the blood pressure fell to 58.2 +/- 4.5 torr from a baseline of 119.0 +/- 10.0 torr. The blood pressure fell to 48.0 +/- 5.0 torr in the four Group-II survivors. After a transient maintenance of baseline blood pressure in Group III, a precipitous drop in blood pressure with death in 10-18 minutes occurred in all these animals. In this porcine model of thoracic aortic injury, PASG inflation increases hemorrhage and mortality.(ABSTRACT TRUNCATED AT 250 WORDS)     

Concurrent increases in brain electrical activity and intracranial blood flow velocity during low-dose ketamine anaesthesia

The purpose of the present study was to assess the effects of low-dose ketamine on spontaneous brain electrical activity (EEG) and intracranial blood flow velocity. Twenty healthy volunteers were divided into two groups: Group I (n = 10) received 0.25 mg.kg-1 ketamine iv; Group II (n = 10) received 0.5 mg.kg-1 ketamine iv. Mean arterial blood pressure (MAP), heart rate (HR), end-tidal PCO2 (PETCO2), and arterial oxygen saturation (SaO2) were measured. The EEG was recorded from temporo-occipital recording sites over both hemispheres. Blood flow velocity in the middle cerebral artery was measured using a transcranial Doppler ultrasound system. All variables were evaluated at baseline and for 60 min following ketamine. Administration of ketamine resulted in increases of MAP and HR in both groups to a similar degree. The PETCO2 and SaO2 did not change in either group over time. Ketamine caused a dose-dependent, transient shift in the EEG to synchronous high-voltage slow waves with an increase in total power (Group I: 301 +/- 38%; Group II: 104 +/- 28%). These changes were associated with dose-dependent increases in mean blood flow velocity (Group I: 35 +/- 7%; Group II: 68 +/- 10%). Our data suggest that increases in intracranial blood flow velocity are closely correlated to increases in neuronal activity and are not secondary to changes in systemic haemodynamic variables.     

Pulmonary dysfunction in patients with femoral shaft fracture treated with intramedullary nailing

BACKGROUND: This study was undertaken to determine whether alveolar dead space increases during intramedullary nailing of femoral shaft fractures and whether alveolar dead space predicts postoperative pulmonary dysfunction in patients undergoing intramedullary nailing of a femoral shaft fracture. METHODS: All patients with a femoral shaft fracture were prospectively enrolled in the study unless there was evidence of acute myocardial infarction, shock, or heart failure. Arterial blood gases were measured at three consecutive time-periods after induction of general anesthesia: before intramedullary nailing and ten and thirty minutes after intramedullary nailing. The end-tidal carbon-dioxide level, minute ventilation, positive end-expiratory pressure, and percent of inspired and expired inhalation agent were recorded simultaneously with the blood-gas measurement. Postoperatively, all subjects were monitored for evidence of pulmonary dysfunction, defined as the need for mechanical ventilation or supplemental oxygen (at a fraction of inspired oxygen of >40%) in the presence of clinical signs of a respiratory rate of >20 breaths/min or the use of accessory muscles of respiration. RESULTS: Seventy-four patients with a total of eighty femoral shaft fractures completed the study. Fifty fractures (62.5%) underwent nailing after reaming, and thirty fractures (37.5%) underwent nailing with minimal or no reaming. The mean alveolar dead-space measurements before canal opening and at ten and thirty minutes after canal opening were 14.5%, 15.8%, and 15.2% in the total series of seventy-four patients (general linear model, p = 0.2) and 20.5%, 22.7%, and 24.2% in the twenty patients with postoperative pulmonary dysfunction (general linear model, p = 0.05). Of the twenty-one patients with an alveolar dead-space measurement of >20% thirty minutes after nailing, sixteen had postoperative pulmonary dysfunction. According to univariate and multivariate analysis, the alveolar dead-space measurement was strongly associated with postoperative pulmonary dysfunction. CONCLUSIONS: According to our data, intramedullary nailing of femoral shaft fractures did not significantly increase alveolar dead space, and the amount of alveolar dead space can predict which patients will have pulmonary dysfunction postoperatively.