Lower leg blood pressure decreases while calf external pressure increases with the angulation of the Trendelenburg position in the lithotomy position with calf- and foot-supported leg holders.

Patients who underwent lower abdominopelvic surgeries in the lithotomy position (LP) and the Trendelenburg position (TP) with the leg holder are at risk of developing well leg compartment syndrome (WLCS). However, contributing factors related to the LP with TP associated with WLCS are unknown. This study aimed to investigate the associations between external pressure at the calf in the LPs at different angulations of the TP and physiological characteristics. Eighty-four university students (age, 21.7 ± 0.9; 42 men and 42 women) voluntarily participated in the study. The awake participants were placed in the LPs using the calf- and foot-supported leg holder at 0° (horizontal level), 5°, 10°, and 20° head-down tilts by moving the electric operating table. The peak contact pressure (pCP) was measured at the calf as a representative external pressure using the pressure distribution measurement system BIG-MAT®. Lower leg blood pressure significantly decreased with TP angulation, while calf pCP significantly increased with it at 0°, 5°, 10°, and 20° head-down tilts (39.4 ± 15.2, 46.5 ± 17.7, 47.2 ± 16.9, and 50.3 ± 17.6 mmHg, respectively). The calf pCP with a 10° head-down tilt was correlated positively with the calf total force (P < 0.001) and negatively with the calf contact area (P < 0.001). Blood hypoperfusion due to low lower leg blood pressure secondary to lower leg elevation and head-down tilt, and high calf external pressure due to direct external compression from the leg holder where it is loaded may contribute to WLCS.

Ageing, obesity, dyslipidaemia, and hospital-room hypertension are clinical risk factors relating to pre-anaesthesia.

BACKGROUND: Pre-anaesthesia hypertension (PAH) occurs when the blood pressure (BP) in patients before surgery, in the operating room, before anaesthesia induction, temporally elevates regardless of normal ambulatory recorded BP or self-measured BP at home. PAH might be caused by anxiety and mental stress about the anaesthesia and surgery. We know that most of the patients with sustained hypertension (SH) are elders, males, obese subjects, and dyslipidaemic subjects. Furthermore, most of the patients with white coat hypertension, which is caused by mental stress about the medical environment of an outpatient, clinic, and hospital ward, are elders, females, and non-smokers. In the present study, we investigated some relevant clinical characteristics influencing PAH. METHODS: Sampling data on patients more than 20 years old, who underwent consecutive operations under general, intrathecal, or epidural anaesthesia were retrospectively collected from hospital records and anaesthesia records. Hospital-room hypertension (HH) was defined as systolic BP (sBP) greater than or equal to 140 mm Hg in the hospital room before anaesthesia and surgery. Operating-room hypertension (OH) was defined as sBP greater than or equal to 140 mm Hg in the operating room before anaesthesia induction. RESULTS: 112 and 119 patients belonged to the OH and operating-room normotension (ON) groups, respectively. The OH group members were significantly older than the ON group members. Body mass index in the OH group was significantly greater than in the ON group. The proportions of males, dyslipidaemic subjects, and non-smokers in the OH group were significantly higher than in the ON group. In the logistic regression analysis, age, body mass, dyslipidaemia, and HH were selected as significant factors that contribute independently to OH (odds ratios; 1.045, 1.031, 2.912, and 4.354, respectively). CONCLUSIONS: The clinical characteristics of the patients with OH are: elders, obese subjects, dyslipidaemic subjects, and hospital-room hypertensive subjects. Ageing, obesity, dyslipidaemia, and HH are clinical risk factors relating to PAH.

Shortened cataract surgery by standardisation of the perioperative protocol according to the Joint Commission International accreditation: a retrospective observational study.

OBJECTIVES: To investigate the impact of standardisation of the perioperative protocol based on the Joint Commission International (JCI) accreditation guidelines for operating time in cataract surgery. DESIGN: Retrospective observational study. SETTING: Single centre in Japan. PARTICIPANTS: Between March 2014 and June 2016, 3127 patients underwent cataract surgery under topical anaesthesia including 2581 and 546 patients before and after JCI accreditation, respectively. PRIMARY AND SECONDARY OUTCOMES: We compared three time periods, comprising the preprocedure/surgery time (pre-PT), PT and post-PT, and total PT (TPT) of cataract surgery between patients before and after JCI accreditation, by regression analysis adjusted for age, sex and cataract surgery-associated confounders. RESULTS: The main outcomes were pre-PT, PT, post-PT and TPT. Pre-PT (19.8±10.5 vs 13.9±8.5 min, p<0.001) and post-PT (3.5±4.6 vs 2.6±2.1 min, p<0.001) significantly decreased after JCI accreditation, while PT did not significantly change (16.8±6.7 vs 16.2±6.3 min, p=0.065). Consequently, TPT decreased on average by 7.3 min per person after JCI accreditation (40.1±13.4 vs 32.8±10.9 min, p<0.001). After adjusting for confounders, pre-PT (ß=-5.82 min, 95% CI -6.75 to -4.88), PT (ß=-0.76 min, 95% CI -1.34 to -1.71), post-PT (ß=-0.85 min, 95% CI -1.24 to -0.45) and TPT (ß=-7.43 min, 95% CI -8.61 to -6.24) were significantly shortened after JCI accreditation. CONCLUSION: Perioperative protocol standardisation, based on JCI accreditation, shortened TPT in cataract surgery under local anaesthesia.

The impact of Joint Commission International accreditation on time periods in the operating room: A retrospective observational study.

The Joint Commission International (JCI) is responsible for upholding standards in healthcare and organizations in compliance receive accreditation. JCI requires quality improvement on patient safety goals, but requirements may prolong the total procedure/surgery time and reduce efficiency. Here, we evaluate the impact of JCI requirements on time periods in the operating room. We included patients who received elective and emergency surgeries under general anesthesia at Juntendo University Hospital between December 2014 and June 2016. Patients were classified as before and after JCI accreditation on December 12, 2015. The primary outcome was total procedure/surgery time. Secondary outcomes include five time periods comprising the total procedure/surgery time: pre-anesthesia time, anesthesia induction time, procedure/surgery time, anesthesia awareness time and post-anesthesia time. We compared these time periods between patients before and after JCI accreditation and patients were matched for age, sex and the specific type of surgery. Although total procedure/surgery time did not change significantly, pre-anesthesia time significantly increased (8.2 ± 6.9 minutes vs. 8.5 ± 6.9 minutes, before vs. after JCI, respectively, p = 0.028) and anesthesia induction time significantly decreased (34.4 ± 16.1 minutes vs. 33.6 ± 15.4 minutes, before vs. after JCI, respectively, p = 0.037) after JCI accreditation. Other secondary study outcomes did not change significantly. Quality improvement initiatives associated with time periods in the operating room can be achieved without undermining efficiency.

Administration of plasma-derived coagulation factor VIII during the perioperative period of mastectomy for breast cancer with acquired von Willebrand syndrome.

BACKGROUND: Acquired von Willebrand syndrome (aVWS) is a rare bleeding disorder with laboratory findings similar to those of congenital von Willebrand disease (VWD). Patients with aVWS may require prophylactic treatment to prevent excessive bleeding following surgery. To our knowledge, to date, there have been no reports on perioperative management for breast cancer patients with aVWS. CASE PRESENTATION: A 60-year-old woman with breast cancer was diagnosed with aVWS due to polycythemia vera. Pre-operative laboratory testing showed a high platelet count and low von Willebrand factor (VWF) activity. The VWF activity did not improve despite an attempt to suppress platelet count with hydroxyurea. Therefore, we decided to perioperatively supplement with plasma-derived factor VIII (FVIII) containing von Willebrand factor (FVIII/VWF concentrates) to perform curative surgery for breast cancer safely. Consequently, the patient did not develop hemorrhage during/after surgery and was discharged on postoperative day 7, as planned, without problems. CONCLUSIONS: For a patient with aVWS, which carries a high risk of hemorrhage during the perioperative period, initiation of appropriate management like supplementation of FVIII/VWF concentrates might enable safe curative surgery for breast cancer, and collaboration with the hematology department is critical.

Evaluation of external pressure to the sacral region in the lithotomy position using the noninvasive pressure distribution measurement system.

BACKGROUND: Pressure ulcers (PUs) in the sacral region can be a complication of surgical procedures performed in the lithotomy position. Previous reports have noted a difference between men and women in PU development related to the supine position, and body weight and body mass index (BMI) have been also described as known risk factors in supine position-related PU development. The BIG-MAT® system is a noninvasive pressure distribution measurement device used to measure external pressure (EP). We used this system to investigate the relationship between EP to the sacral region in the lithotomy position and selected physical characteristics. METHODS: We recruited 21 young, healthy volunteers (11 men and 10 women, aged 21.4±0.5 years). Using the BIG-MAT system, we measured four types of EP to the sacral region: box pressure, peak box pressure, contact pressure, and peak contact pressure. We analyzed the relationships between these dynamic parameters and physical characteristics of the participants. RESULTS: There were no differences between men and women in the four types of EP, and no significant differences related to the participants' height, weight, or BMI. CONCLUSION: An individual's height, weight, and BMI may not contribute to the risk of inducing lithotomy position-related PUs in the sacral region. The noninvasive pressure distribution measurement system BIG-MAT for patients in the lithotomy position during surgery could become a significant device when estimating EP at the sacral region.

Temperature-dependent inotropic and lusitropic indices based on half-logistic time constants for four segmental phases in isovolumic left ventricular pressure-time curve in excised, cross-circulated canine heart.

Varying temperature affects cardiac systolic and diastolic function and the left ventricular (LV) pressure-time curve (PTC) waveform that includes information about LV inotropism and lusitropism. Our proposed half-logistic (h-L) time constants obtained by fitting using h-L functions for four segmental phases (Phases I-IV) in the isovolumic LV PTC are more useful indices for estimating LV inotropism and lusitropism during contraction and relaxation periods than the mono-exponential (m-E) time constants at normal temperature. In this study, we investigated whether the superiority of the goodness of h-L fits remained even at hypothermia and hyperthermia. Phases I-IV in the isovolumic LV PTCs in eight excised, cross-circulated canine hearts at 33, 36, and 38 °C were analyzed using h-L and m-E functions and the least-squares method. The h-L and m-E time constants for Phases I-IV significantly shortened with increasing temperature. Curve fitting using h-L functions was significantly better than that using m-E functions for Phases I-IV at all temperatures. Therefore, the superiority of the goodness of h-L fit vs. m-E fit remained at all temperatures. As LV inotropic and lusitropic indices, temperature-dependent h-L time constants could be more useful than m-E time constants for Phases I-IV.

Half-Logistic Function Model for First Half of Descending Phase of Cardiomyocyte Cytoplasmic Ca(2+) Concentration ([Ca(2+)]i)-Time Curve (CaTCIII) in Isolated Aequorin-Injected Mouse Left Ventricular Papillary Muscle.

BACKGROUND: Myocardial contraction and relaxation are regulated by increases and decreases in cytoplasmic calcium concentration ([Ca(2+)]i). In previous studies, we found that a half-logistic (h-L) function, which represents a half-curve of a symmetrical sigmoid logistic function with a boundary at the inflection point, curve-fits the first half of the ascending phase and the second half of the descending phase of the [Ca(2+)]i transient curve better than a mono-exponential (m-E) function. In the present study, we investigated the potential application of an h-L function to analyse the first half of the descending phase of CaTC (CaTCIII). METHODS: The [Ca(2+)]i was measured using the Ca(2+)-sensitive aequorin, which was microinjected into 15 isolated mouse left ventricular (LV) papillary muscles. The observed CaTCIII data in the interval from the point corresponding to the peak [Ca(2+)]i to the point corresponding to dCa/dtmin was curve-fitted using the h-L and m-E function equations by the least-squares method. RESULTS: The mean correlation coefficient (r) values of the h-L and m-E function best curve-fits for 11 CaTCIIIs were 0.9986 and 0.9982, respectively. The Z transformation of h-L r (3.64 ± 0.45) was larger than that of m-E r (3.50 ± 0.33) (p < 0.05). CONCLUSIONS: The h-L function can evaluate most CaTCIIIs more accurately than the m-E function in isolated aequorin-injected mouse LV papillary muscle. The three calculated h-L parameters i.e., amplitude constant, time constant, and non-zero asymptote, are more reliable indices than m-E for evaluating the magnitude and time course of the change in the decrease in [Ca(2+)]i. KEY WORDS: Ca(2+) transient; Half-logistic amplitude constant; Half-logistic non-zero asymptote; Half-logistic time constant; Myocardial Ca(2+) handling.

Male sex, height, weight, and body mass index can increase external pressure to calf region using knee-crutch-type leg holder system in lithotomy position.

BACKGROUND: Well-leg compartment syndrome (WLCS) is one of the catastrophic complications related to prolonged surgical procedures performed in the lithotomy position, using a knee-crutch-type leg holder (KCLH) system, to support the popliteal fossae and calf regions. Obesity has been implicated as a risk factor in the lithotomy position-related WLCS during surgery. In the present study, we investigated the relationship between the external pressure (EP) applied to the calf region using a KCLH system in the lithotomy position and selected physical characteristics. METHODS: Twenty-one young, healthy volunteers (21.4±0.5 years of age, eleven males and ten females) participated in this study. The KCLH system used was Knee Crutch(®). We assessed four types of EPs applied to the calf region: box pressure, peak box pressure, contact pressure, and peak contact pressure, using pressure-distribution measurement system (BIG-MAT(®)). Relationships between these four EPs to the calf regions of both lower legs and a series of physical characteristics (sex, height, weight, and body mass index [BMI]) were analyzed. RESULTS: All four EPs applied to the bilateral calf regions were higher in males than in females. For all subjects, significant positive correlations were observed between all four EPs and height, weight, and BMI. CONCLUSION: EP applied to the calf region is higher in males than in females when the subject is supported by a KCLH system in the lithotomy position. In addition, EP increases with the increase in height, weight, and BMI. Therefore, male sex, height, weight, and BMI may contribute to the risk of inducing WLCS.

[Inguinal Approach in Obturator Nerve Block].

The most commonly utilized approaches to obtura- tor nerve block are the pubic approach and the inter- adductor approach. However, the pubic approach is difficult and extremely invasive because a needle must be inserted into the pelvis and there have been some cases of vascular puncture using the pubic approach. Moreover, some cases accompanied clinical signs of local anesthetic toxicity using both approaches. Thus, we devised and performed the inguinal approach, where the femoral artery and vein are shifted outward in the level of the inguinal crease and the needle is inserted vertically from the innerside of them using electric stimulation. However, we experienced some unsuccessful cases due to a single branch block, be- cause the obturator nerve is separated into the ante- rior and posterior branches at the level of the inguinal crease. Choquet reported a new inguinal approach that blocks both branches which is easy and useful because the frequency of the needle insertion is less ; the block performance time is shorter ; the success rate is higher ; and the pain and discomfort are less than that with the pubic approach.

Factors that increase external pressure to the fibular head region, but not medial region, during use of a knee-crutch/leg-holder system in the lithotomy position.

BACKGROUND: Paralysis of the common peroneal nerve is one of the relatively common nerve injuries related to the lithotomy position with the use of a knee-crutch/leg-holder system. Several risk factors have been implicated in lithotomy position-related common peroneal nerve paralysis during operation. MATERIALS AND METHODS: In the present study, 21 young healthy volunteers participated in the investigation of the causes of the paralysis of the common peroneal nerve in the lithotomy position using a knee-crutch/leg-holder; Knee Crutch. We assessed the external pressure applied to the fibular head and medial regions using the Big-Mat pressure-distribution measurement system. Relationships between the peak contact pressure and physical characteristics, such as sex, height, weight, body mass index (BMI), and fibular head circumference, were analyzed. RESULTS: The peak contact pressure to the fibular head region was greater for males than for females. For all subjects, significant positive correlations were observed between the peak contact pressure to the fibular head region and weight, BMI, or fibular head circumference. However, there was no significant difference between the peak contact pressure to the fibular head region and height for any subjects. Moreover, there was no sex-related difference in the peak contact pressure to the fibular medial region, and no significant differences between the peak contact pressure to the fibular medial region and height, weight, BMI, or fibular head circumference. CONCLUSION: External pressure to the fibular head region is greater for males than for females using a knee-crutch/leg-holder system in the lithotomy position. In addition, the external pressure to the fibular head region, but not the fibular medial region, increases with increasing weight, BMI, and fibular head circumference. Therefore, these patient-related characteristics may contribute to the risk of developing lower-extremity neuropathy, leading to injury or ischemia of the common peroneal nerve.

[Measurement of external pressure of peroneal nerve tract coming in contact with lithotomy leg holders using pressure distribution measurement system BIG-MAT®].

We investigated external pressure on peroneal nerve tract coming in contact with two kinds of leg holders using pressure distribution measurement system BIG- MAT® (Nitta Corp., Osaka) in the lithotomy position Peak contact (active) pressure at the left fibular head region coming in contact with knee-crutch-type leg holder M® (Takara Belmont Corp., Osaka), which supports the left popliteal fossa, was 78.0 ± 26.4 mmHg. On the other hand, peak contact pressure at the left lateral lower leg region coming in contact with boot-support-type leg holder Bel Flex® (Takara Belmont Corp., Osaka), which supports the left lower leg and foot was 26.3±7.9 mmHg. These results suggest that use of knee-crutch-type leg holder is more likely to induce common peroneal nerve palsy at the fibular head region, but use of boot-support-type leg holder dose not easily induce superficial peroneal nerve palsy at the lateral lower leg region, because capillary blood pressure is known to be 32 mmHg. Safer holders for positioning will be developed to prevent nerve palsy based on the analysis of chronological change in external pressure using BIG-MAT® system during anesthesia.

[Compression of facial skin by headrest in prone position].

The higher body pressures of patients compared to their capillary blood pressures in the limited areas of their skin induced peripheral blood flow disturbances, thus causing skin injuries. Use of horseshoe-shaped headrest for prone-positioning during surgeries can induce blood flow occlusion, skin ischemia, and skin injury due to high pressure and shear stress on the forehead and both cheeks, which are protrusions on facial bone. The use of pressure dispersion headrests is preferred, redistributing the body pressure equally and absorbing pressure from the entire head in the prone position for surgery.

[Perioperative management in children with sleep apnea syndrome (SAS) undergoing adenoidotonsillectomy].

We should take care of the occurrences of apnea and hypopnea after emergence from general anesthesia in the children with sleep apnea syndrome (SAS) due to an increase in sensitivity to opioid agonists given for previous recurrent hypoxia. Preoperative assessment for SAS with apnea hypopnea index (AHI), oxygen desaturation index (ODI), and minimum artery oxygen saturation by pulse oxymetry (lowest SpO2) obtained from polysomnography (PSG) test could help to predict the postoperative respiratory depression. In perioperative management in the children with SAS who are candidates for adenotonsillectomy, the dose of opioid agonists during anesthesia maintenance for purpose of postoperative analgesia and sedation should be reduced; postoperative respiratory and circulatory management with monitoring of respiratory movement of the thoracoabdominal part, and electrographic (ECG) and SpO2 monitoring should be continued intensively under long-term oxygen administration; and airway management, nasal continuous positive airway pressure (nCPAP), and artificial ventilation should be prepared for the occurrence of postoperative respiratory depression.

[Flumazenil].

Flumazenil, an imidazobenzodiazepine derivative, has been generally used as an antagonist which antagonizes the hypnotic and sedative effects of benzodiazepines at gamma-amino butyric acid receptors. The anesthetic effects induced by benzodiazepine could be reversed effectively and safely by flumazenil alone, and some have recommended diagnostic usage in intensive care unit and emergency unit as well, for suspected benzodiazepine intoxication. Seizures might follow the use of flumazenil. Benzodiazepine overdose patients who have co-ingested tricyclic and tetracyclic antidepressants are especially at risk for this complication. Therefore, flumazenil could be considered in cases in which quick recovery is required and should be administered intravenously in small, incremental doses.

Intracellular Ca(2+) Transient Phase II Can be Assessed by Half-Logistic Function Model in Isolated Aequorin-Injected Mouse Left Ventricular Papillary Muscle.

BACKGROUND: Myocardial contraction and relaxation are regulated by increases and decreases in intracellular cytoplasmic calcium (Ca(2+)) concentration ([Ca(2+)]i). In previous studies, we found that a half-logistic (h-L) function, which represents a half-curve of a symmetrical sigmoid logistic function with a boundary at the inflection point, curve-fits the first half of the ascending phase (CaTI) and the second half of the descending phase of the [Ca(2+)]i transient curve (CaTIV) better than a mono-exponential (m-E) function. In the present study, we investigated the potential application of an h-L function to the analysis of the second half of the ascending phase of the [Ca(2+)]i transient curve (CaTII). METHODS: The [Ca(2+)]i transient was measured using the Ca(2+)-sensitive photoprotein aequorin, which was microinjected into 15 isolated left ventricular (LV) papillary muscles of mice. The observed CaTII data during the time duration from the point corresponding to the maximum of the first-order time derivative of Ca(2+) concentration (dCa/dtmax) to the point corresponding to the peak Ca(2+) concentration was curve-fitted by the least-squares method using the h-L and m-E function equations. RESULTS: The mean correlation coefficient (r) values of the h-L and m-E curve-fits for CaTII were 0.9996 and 0.9984, respectively. The Z transformation of h-L r was larger than that of m-E r (p < 0.0001). H-L residual mean square (RMS) was smaller than m-E RMS (p < 0.001). CONCLUSIONS: The h-L function tracks the magnitudes and time courses of CaTII more accurately than the m-E function in isolated aequorin-injected mouse LV papillary muscle. Compared with the m-E time constant, the h-L time constant of CaTII is a more reliable index for evaluating the time duration of the change in the increase in [Ca(2+)]i during the combination of the middle part of the contraction process and the early part of the relaxation process. CaTII can be assessed by the h-L function model in cardiac muscles. The h-L approach may provide a more useful model for studying each process in myocardial Ca(2+) handling. KEY WORDS: Calcium handling; Calcium transient; Curve-fit; Half-Logistic function; Time constant.

Pre-anesthesia systolic blood pressure increases with age regardless of sex.

PURPOSE: Pre-anesthesia hypertension (PAH) is the temporary elevation of blood pressure (BP), compared with normal ambulatory recorded BP or self-measured BP at home, in patients waiting for operation in the operating room (OR) before anesthesia induction. In general, the incidence of sustained hypertension (SH) increases progressively with age and the increase is greater in males than in females. In this study, we investigated the influence of age and sex on PAH. METHODS: Sampling data on consecutive patients who were more than 20 years old and who had undergone surgery under general, intrathecal, or epidural anesthesia were retrospectively collected from hospital records and anesthesia records. Patients with SH, which was defined as a past history of hypertension and taking oral antihypertensive medications, were excluded from the analyses, and the data of 231 patients, 102 males and 129 females, were used for the analyses. RESULTS: The proportions of male and female patients with a systolic BP (sBP) of more than 140 mmHg in the OR before anesthesia induction were 55.9 and 42.6%, respectively. The proportions of male and female patients with a diastolic BP (dBP) of more than 90 mmHg were 34.3 and 23.3%, respectively. There was no difference in the proportions of male and female patients with PAH. The differences in sBP between measurements in the hospital room (HR) before the operation and those in the OR (ΔsBP) in males and females were 22.9 ± 25.6 and 19.0 ± 24.0 mmHg, respectively. The differences in dBP between measurements in the HR and those in the OR (ΔdBP) in males and females were 12.7 ± 16.5 and 8.4 ± 17.9 mmHg, respectively. There were no differences in ΔsBP and ΔdBP between males and females. The sBP in the OR and the ΔsBP increased significantly with age in both males and females. CONCLUSION: Age is an important clinical factor related to PAH. Pre-anesthesia sBP and the change in pre-anesthesia sBP increase progressively with age regardless of sex. These findings suggest that the higher BP seen in the elderly in the OR before anesthesia induction, as reported previously, might be explained in part by a greater impact of PAH in older people.

[Design, equipment, and management for air conditioning in operating room].

In order to maintain air cleanliness in the operating room (OR) permanently, air exchange rate in the OR should be more than 15 times x hr(-1), the laminar air flow should be kept, and the numbers of the persons in the OR and the numbers of opening and closing OR door should be limited. High efficiency particulate air (HEPA) filter is effective in collection and removal of airborne microbes, and is used in the biological clean room. We need to design, equip, and manage the OR environment according to Guideline for Design and Operation of Hospital HVAC Systems HEAS-02-2004 established by Healthcare Engineering Association of Japan and Guideline for Prevention of Surgical Site Infection (SSI) established by the Center for Disease Control and Prevention (CDC) in the USA.

Calcium-induced calcium release from the sarcoplasmic reticulum can be evaluated with a half-logistic function model in aequorin-injected cardiac muscles.

PURPOSE: Release of calcium (Ca(2+)) from the sarcoplasmic reticulum (SR) induced by Ca(2+) influx through voltage-dependent sarcolemmal L-type Ca(2+) channels (CICR) in cardiac muscle cells has been implicated as a potential target contributing to anesthetic-induced myocardial depression. In an earlier study, we found that (1) a half-logistic (h-L) function, which represents a half-curve of a sigmoid logistic function with a boundary at the inflection point, curve-fits the first half of the ascending phases of the isometric myocardial tension and isovolumic left ventricular (LV) pressure waveforms better than a mono-exponential (m-E) function and (2) the h-L time constants are useful as inotropic indices. We report here our investigation of the potential application of an h-L function to the analysis of the first half of the ascending phase of the Ca(2+) transient curve (faCaT) that precedes and initiates myocardial contraction and the increase in LV pressure. METHODS: Ca(2+) transients (CaT) were measured using the Ca(2+)-sensitive photoprotein aequorin, which was microinjected into seven isolated rabbit right ventricular and 15 isolated mouse LV papillary muscles. The faCaT data from the beginning of twitch stimulation to the maximum of the first-order time derivative of Ca(2+) concentration (dCa/dt(max)) was curve-fitted by the least-squares method using h-L and m-E function equations. RESULTS: The mean correlation coefficient (r) values of the h-L and m-E curve-fits for the faCaTs were 0.9740 and 0.9654 (P < 0.05) in the rabbit and 0.9895 and 0.9812 (P < 0.0001) in the mouse. CONCLUSION: The h-L curves tracked the amplitudes and time courses of the faCaTs in cardiac muscles more accurately than m-E functions. Based on this result, we suggest that the h-L time constant may be a more reliable index than the m-E time constant for evaluating the rate of CICR from the SR in myocardial Ca(2+) handling. The h-L approach may provide a more useful model for the study of CICR during the contraction process induced by anesthetic agents.