function acidBase(form) {
	var ph = form.ph.value
	var pco2 = form.pco2.value
	var hco3 = form.hco3.value
	
	var na = form.na.value
	var bicarb = form.bicarb.value
	var cl = form.cl.value

	var whatText, expectedPco2, expectedText, phHigh, phLow, hco3High, hco3Low, ehco3, eph, eco2, agap
	
	if ((ph == "") || (ph <=0) || (isNaN(ph))) {
		alert("Please enter the pH.");
		form.ph.focus();
		form.ph.select();
		return false;
	}
	
	if ((pco2 == "") || (pco2 <=0) || (isNaN(pco2))) {
		alert("Please enter the pCO2.");
		form.pco2.focus();
		form.pco2.select();
		return false;
	}

	if ((hco3 == "") || (hco3 <=0) || (isNaN(hco3))) {
		alert("Please enter the HCO3.");
		form.hco3.focus();
		form.hco3.select();
		return false;
	}

	eph = 6.1 + Math.log(hco3 / (pco2 * 0.0301)) / Math.log(10);
	ehco3 = Math.pow(10,(ph - 6.1)) * 0.0301 * pco2;
	eco2 = hco3 / (0.0301 * Math.pow(10,(ph - 6.1)));
	
	eph = roundNum(eph,2);
	ehco3 = roundNum(ehco3,0);
	eco2 = roundNum(eco2,0);
	
	
//  Primary Metabolic Disorders
	if ((ph < 7.36) && (pco2 <= 40)) {
		whatText = "Primary metabolic acidosis"
		expectedPco2 = 1.5 * hco3 + 8
		agap = anionGap(na,bicarb,cl,1)
		if (agap <= 16) {whatText += ", with normal anion gap"}
			else {
				whatText += ", with increased anion gap"
				var agapChange = agap - 12
				var bicarbChange = 24 - hco3
				
				if ((agapChange - bicarbChange) > 7) {whatText += ",\nmixed with a metabolic alkalosis"}
				if ((agapChange - bicarbChange) < -7) {whatText += ",\nmixed with a normal-gap metabolic acidosis"}			
			}
	}
	
	if ((ph > 7.44) && (pco2 >= 40)) {
		whatText = "Primary metabolic alkalosis"
		expectedPco2 = 0.7 * hco3 + 21
	}

	expectedPco2 = roundNum(expectedPco2,0);
	
	if (pco2 > (expectedPco2 + 2)) {whatText += ",\nwith superimposed respiratory acidosis"}
	if (pco2 < (expectedPco2 - 2)) {whatText += ",\nwith superimposed respiratory alkalosis"}
	if ((pco2 <= (expectedPco2 + 2)) && (pco2 >= (expectedPco2 - 2))) {whatText += ",\nwith full respiratory compensation"}

	expectedText = "(expected Pco2 = " + (expectedPco2 - 2) + " - " + (expectedPco2 + 2) + ")";
	
	
//  Primary Respiratory Disorders
	if ((ph < 7.4) && (pco2 > 44)) {
		whatText = "primary respiratory acidosis";
		phHigh = 7.4 - (0.003 * (pco2 - 40));
		phLow = 7.4 - (0.008 * (pco2 - 40));
		hco3High = 24 + (0.35 * (pco2 - 40));
		hco3Low = 24 + (0.1 * (pco2 - 40));

		phLow = roundNum(phLow,2);
		phHigh = roundNum(phHigh,2);
		hco3Low = roundNum(hco3Low,0);
		hco3High = roundNum(hco3High,0);
	
		if (ph <= (phLow + 0.02)) {
			whatText = "Acute (uncompensated) " + whatText;
			if (hco3 < (hco3Low - 2)) {
				whatText += ",\nwith metabolic acidosis"
				agap = anionGap(na,bicarb,cl,1)
				if (agap <= 16) {whatText += ", with normal anion gap"}
					else {whatText += ", with increased anion gap"}
			}
		}

		if (ph >= (phHigh - 0.02001)) {
			whatText = "Chronic (compensated) " + whatText;
			if (hco3 > (hco3High + 2)) {
				whatText += ",\nwith metabolic alkalosis"
			}
		}
		
		if ((ph > (phLow + 0.02)) && (ph < (phHigh - 0.02001))) {
			whatText = "(1) partially compensated primary respiratory acidosis, or\n" +
			"(2) acute superimposed on chronic " + whatText + ", or\n" +
			"(3) mixed acute respiratory acidosis with a small metabolic alkalosis"}
	
		expectedText = "pH < " + phLow + " and HCO3 < " + hco3Low + ", for acute (uncompensated)\n" +
			"pH > " + phHigh + " and HCO3 > " + hco3High + ", for chronic (compensated)"
	}
	
	if ((ph > 7.4) && (pco2 < 36)) {
		whatText = "primary respiratory alkalosis"
		phLow = 7.4 + (0.0017 * (40 - pco2));
		phHigh = 7.4 + (0.008 * (40 - pco2));
		hco3Low = 24 - (0.5 * (40 - pco2));
		hco3High = 24 - (0.25 * (40 - pco2));

		phLow = roundNum(phLow,2);
		phHigh = roundNum(phHigh,2);
		hco3Low = roundNum(hco3Low,0);
		hco3High = roundNum(hco3High,0);

		if (ph <= (phLow + 0.02)) {
			whatText = "Chronic (compensated) " + whatText;
			if (hco3 < (hco3Low - 2)) {
				whatText += ",\nwith metabolic acidosis"
				agap = anionGap(na,bicarb,cl,1)
				if (agap <= 16) {whatText += ", with normal anion gap"}
					else {whatText += ", with increased anion gap"}
			}
		}
		
		if (ph >= (phHigh - 0.02)) {
			whatText = "Acute (uncompensated) " + whatText;
			if (hco3 > (hco3High + 2)) {whatText += ",\nwith metabolic alkalosis"}
		}

		if ((ph > (phLow + 0.02)) && (ph < (phHigh - 0.02))) {
			whatText = "(1) partially compensated primary respiratory alkalosis, or\n" +
			"(2) acute superimposed on chronic " + whatText + ", or\n" +
			"(3) mixed acute respiratory alkalosis with a small metabolic acidosis"}

		expectedText = "pH > " + phHigh + " and HCO3 > " + hco3High + ", for acute (uncompensated)\n" +
			"pH < " + phLow + " and HCO3 < " + hco3Low + ", for chronic (compensated)"
	}
	

//  Mixed Acid-Base Disorders
if ((whatText == "") || (whatText == null)) {
	if ((ph >= 7.36) && (ph <= 7.44)) {
		if ((pco2 > 40) && (hco3 > 26)) {
			whatText = "Mixed respiratory acidosis / metabolic alkalosis"
			expectedPco2 = 0.7 * hco3 + 21
		} else
		
		if ((pco2 < 40) && (hco3 < 22)) {
			whatText = "Mixed respiratory alkalosis / metabolic acidosis"
			expectedPco2 = 1.5 * hco3 + 8
			agap = anionGap(na,bicarb,cl,1)
			if (agap <= 16) {whatText += ", with normal anion gap"}
				else {whatText += ", with increased anion gap"}
		} else
		
		{	agap = anionGap(na,bicarb,cl,0)
			if (agap > 16) {whatText = "Mixed metabolic alkalosis / metabolic acidosis, with increased anion gap"}
		}		
		
		expectedPco2 = roundNum(expectedPco2,0);
		expectedText = "(expected Pco2 = " + (expectedPco2 - 2) + " - " + (expectedPco2 + 2) + ")";
	}
}

//  Check for Elevated Anion Gap Acidosis
	if ((agap == "") || (agap == null)) {
		agap = anionGap(na,bicarb,cl,0)
		if (agap > 16) {
			whatText += ",\nwith metabolic acidosis, with increased anion gap"
		}
	}


//  Normal ABG
	if ((whatText == "") || (whatText == null)) {
		whatText = "Normal ABG";
		expectedText = " "
	}
	
	expectedText2 = "expected pH = " + eph + "\nexpected CO2 = " + eco2 + "\nexpected HCO3- = " + ehco3
	form.interp.value = whatText + "\n\n" + expectedText + "\n\n" + expectedText2;
	return true;
}


function anionGap(na,bicarb,cl,metAcid) {
	var addText
	var isAgap = document.acids.agap.value
	
	if (metAcid == 1) {addText = "METABOLIC ACIDOSIS\n"} else {addText = ""}
	if ((isAgap != "") && (isAgap != null) && (!isNaN(isAgap))) {
		if ((na=="") || (na==null) || (bicarb=="") || (bicarb==null) || (cl=="") || (cl==null)) {	return isAgap}
	}
	if ((na == "") || (na == null) || (na <=0) || (isNaN(na))) {
		if (metAcid == 0) {return true} else {
			alert(addText + "Please enter a sodium value.");
			document.acids.na.focus();
			document.acids.na.select();
			return false;
		}
	}
	
	if ((bicarb == "") || (bicarb == null) || (bicarb <=0) || (isNaN(bicarb))) {
		if (metAcid == 0) {return true} else {
			alert(addText + "Please enter a bicarbonate value.");
			document.acids.bicarb.focus();
			document.acids.bicarb.select();
			return false;
		}
	}

	if ((cl == "") || (cl == null) || (cl <=0) || (isNaN(cl))) {
		if (metAcid == 0) {return true} else {
			alert(addText + "Please enter a chloride value.");
			document.acids.cl.focus();
			document.acids.cl.select();
			return false;
		}
	}
	
	var agap = na - bicarb - cl;
	document.acids.agap.value = agap;
	return agap;
}


function changeABG(bicarb) {
	var ABGbicarb = document.acids.hco3.value
	if ((ABGbicarb == "") || (ABGbicarb == null)) {document.acids.hco3.value = bicarb}
	return true
}


function changeBicarb(bicarb) {
	var ChemBicarb = document.acids.bicarb.value
	if ((ChemBicarb == "") || (ChemBicarb == null)) {document.acids.bicarb.value = bicarb}
	return true
}


function roundNum(thisNum,dec) {
	thisNum = thisNum * Math.pow(10,dec)
	thisNum = Math.round(thisNum)
	thisNum = thisNum / Math.pow(10,dec)
	return thisNum
}