maintenance_fluid_calculator.py•6.07 kB
"""
Maintenance Fluid Calculator
"""
from typing import Dict, Any
from medcalc import (
BaseCalculator,
CalculatorInfo,
Parameter,
ParameterType,
ValidationResult,
CalculationResult,
register_calculator
)
from medcalc.utils import round_number
@register_calculator("maintenance_fluid")
class MaintenanceFluidCalculator(BaseCalculator):
"""维持液体计算器实现"""
def get_info(self) -> CalculatorInfo:
return CalculatorInfo(
id=22,
name="Maintenance Fluid Calculator",
category="pharmacology",
description="Calculate maintenance fluid requirements based on body weight",
parameters=[
Parameter(
name="weight",
type=ParameterType.NUMERIC,
required=True,
unit="kg",
min_value=0.5,
max_value=200,
description="Patient weight in kilograms"
)
]
)
def _parse_parameter(self, value: Any) -> tuple[float, str]:
"""解析参数，支持字符串格式如 '30kg' 或 '22lbs'"""
if isinstance(value, (int, float)):
return float(value), ""
if isinstance(value, str):
import re
# 匹配数字和单位
match = re.match(r'^([0-9]*\.?[0-9]+)\s*([a-zA-Z]*)$', value.strip())
if match:
num_str, unit = match.groups()
try:
return float(num_str), unit.lower()
except ValueError:
pass
raise ValueError(f"Invalid parameter format: {value}")
def _convert_weight_to_kg(self, weight: float, unit: str) -> float:
"""将体重转换为千克"""
if unit in ["kg", ""]:
return weight
elif unit in ["g", "grams"]:
return weight / 1000
elif unit in ["lb", "lbs", "pounds"]:
return weight * 0.453592 # 1 lb = 0.453592 kg
elif unit in ["oz", "ounces"]:
return weight * 0.0283495 # 1 oz = 0.0283495 kg
else:
raise ValueError(f"Unsupported weight unit: {unit}")
def validate_parameters(self, parameters: Dict[str, Any]) -> ValidationResult:
"""验证输入参数"""
errors = []
# 检查必需参数
if "weight" not in parameters:
errors.append("weight is required")
return ValidationResult(is_valid=False, errors=errors)
try:
# 解析体重值
weight_value, weight_unit = self._parse_parameter(parameters["weight"])
# 转换为千克
weight_kg = self._convert_weight_to_kg(weight_value, weight_unit)
# 验证范围
if weight_kg <= 0:
errors.append("weight must be greater than 0")
elif weight_kg > 200:
errors.append("weight must be 200 kg or less")
except ValueError as e:
errors.append(f"Invalid weight format: {e}")
return ValidationResult(is_valid=len(errors) == 0, errors=errors)
def calculate(self, parameters: Dict[str, Any]) -> CalculationResult:
"""计算维持液体需求"""
# 解析体重值
weight_value, weight_unit = self._parse_parameter(parameters["weight"])
# 转换为千克
weight = self._convert_weight_to_kg(weight_value, weight_unit)
# 根据体重计算维持液体需求
if weight < 10:
# <10kg: 4 mL/kg/hr
fluid_rate = round_number(weight * 4)
formula = f"{weight} kg × 4 mL/kg/hr"
rule = "For patients with weight less than 10 kg: 4 mL/kg/hr"
elif 10 <= weight <= 20:
# 10-20kg: 40 mL/hr + 2 mL/kg/hr × (weight-10)
fluid_rate = round_number(40 + 2 * (weight - 10))
formula = f"40 mL/hr + 2 mL/kg/hr × ({weight} kg - 10 kg)"
rule = "For patients with weight between 10-20 kg: 40 mL/hr + 2 mL/kg/hr × (weight - 10 kg)"
else:
# >20kg: 60 mL/hr + 1 mL/kg/hr × (weight-20)
fluid_rate = round_number(60 + (weight - 20))
formula = f"60 mL/hr + 1 mL/kg/hr × ({weight} kg - 20 kg)"
rule = "For patients with weight greater than 20 kg: 60 mL/hr + 1 mL/kg/hr × (weight - 20 kg)"
# 计算24小时总量
daily_total = round_number(fluid_rate * 24)
# 生成解释
explanation = self._generate_explanation(weight, fluid_rate, formula, rule, daily_total, weight_value, weight_unit)
return CalculationResult(
value=fluid_rate,
unit="mL/hr",
explanation=explanation,
metadata={
"weight_kg": weight,
"fluid_rate_ml_per_hr": fluid_rate,
"daily_total_ml": daily_total,
"formula": formula,
"rule": rule,
"original_weight": weight_value,
"weight_unit": weight_unit or "kg"
}
)
def _generate_explanation(self, weight: float, fluid_rate: float, formula: str, rule: str, daily_total: float, original_weight: float, weight_unit: str) -> str:
"""生成计算解释"""
explanation = f"""Maintenance Fluid Calculation using the Holliday-Segar method:
{rule}
Patient weight: {original_weight} {weight_unit or 'kg'}"""
# 如果需要单位转换，显示转换信息
if weight_unit and weight_unit.lower() not in ["kg", ""]:
explanation += f" (converted to: {weight:.2f} kg)"
explanation += f"""
Calculation: {formula} = {fluid_rate} mL/hr
Daily total: {fluid_rate} mL/hr × 24 hours = {daily_total} mL/day
The patient's maintenance fluid requirement is {fluid_rate} mL/hr."""
return explanation